UC-NRLF

1

SB

D7b

iTHYMETRK.

OF1 THE

iSH Y/ATER LOCHS

SCOTLAND

i iHE DIRECTION Or

SIR JOHN MURRAY, K.C.B..HR.S.

, . ....

AURENCE PULLAR, HR.S.E.

C

Auu 22 Ibl !
EXCHANGE

LIBRARY

OF THE

UNIVERSITY OF CALIFORNIA.

RECEIVED BY EXCHANGE
Class

BATHYMETRICAL SUKVEY

OF THE

SCOTTISH FRESH-WATER LOCHS

IRcport on tbe Scientific IResuIts

PRICE:

Per set of six volumes, £5, 5s.
Volume I. separate, £1, Is.

All the Maps in these volumes are dis-
sected and mounted on cloth. The
volumes are half -bound in finest pig-skin.

BATHYMETRICAL SURVEY

OF THE

SCOTTISH FRESH- WATER LOCHS

CONDUCTED UNDER THE DIRECTION OF

SIR JOHN MURRAY

K.C.B., F.R.S., D.Sc., ETC.

AND

LAURENCE PULLAE

F.R.S.E., F.R.G.S.
DURING THE YEARS 1897 TO 1909

IReport on tbe Scientific IResnlts

VOLUME II

EDINBURGH
CHALLENGER OFFICE

1910

AUt. 22 191 1
EXCHANGE

Defcicatefc

TO THE MEMORY OF

FREDERICK PATTISON PULLAR

WHO WAS DROWNED
WHILE ATTEMPTING TO SAVE THE LIVES OF OTHERS

ON 15TH FEBRUARY 1Q01
AT THE AGE OF TWENTY-FIVE YEARS

He took an active part in the initiation

of this systematic survey of the

Scottish Fresh-ivater Lochs

216510

PREFACE

THIS publication consists of six volumes, two of text and
four of maps, and gives an account of the work done, of
the observations recorded, and of most of the results
obtained, during an investigation into the bathymetry of
the fresh- water lochs or lakes of Scotland between the
years 1897 and 1909.

Although the determination of the depths of the lakes,
and of the general form of the basins in which they lie,
made up the principal work of the Survey, still a very large
number of observations were carried out in other branches
of the science of limnography. Many of these observations
and the results were published from time to time, as
the work proceeded, in scientific journals, while others
now appear in print for the first time.

Volume I. consists for the most part of new matter.
It includes numerous articles dealing with the general
results of the researches from the topographical, geological,
physical, chemical, and biological points of view, a com-
parison of Scottish lakes with lakes in other parts of the
world, and various theoretical considerations. These
articles have been wrritten chiefly by gentlemen who have
taken an active part in the field-work of the Survey.
This volume also contains an extensive bibliography of
books and special papers referring to lakes.

Volume II. contains the special descriptions of the lakes,
the maps of which appear in Volumes III., IV., V., and VI.
Throughout the text will be found numerous index-maps,
showing the drainage areas of the districts in which the
lochs are situated, together with other illustrations.

The bathymetrical maps have all appeared during the
past eight years in the Journal of the Royal Geographical
Society or in an extra publication of the same Society ;
and some of the maps have also been published in the

vii

viii PREFACE

Magazine of the Royal Scottish Geographical Society.
These maps consist of two series. In the first series
(Volumes III. and IV.), the contours of depth in the lakes
are shown in shades of blue, and the contours of the height
of the surrounding land are shown in brown shades of
colour; in the second series (Volumes V. and VI.), the
contours of depth are shown in shades of blue, the brown
shades on the land being omitted.

In addition to the bathymetrical maps, there are also
a few maps showing the surface geology, the rainfall, and
other physical features of some of the districts.

These maps have all been prepared and printed by
Dr J. G. Bartholomew, and we desire to express our in-
debtedness to him for the care with which these have
been produced, and for his assistance and advice in many
directions. We are also indebted to Messrs G. Cornwall &
Sons, Aberdeen, for their assistance and advice with regard
to the binding of the maps, and to Messrs Neill & Co., Edin-
burgh, for their advice in connection with the letterpress.

We feel confident that the whole investigation has
resulted in very substantial contributions to knowledge.
Some of the observations — those regarding the temperature
seiche, and the variation of the viscosity of the water with
temperature, for example — throw much light on obscure
oceanographical problems. Most of the observations
could, with advantage, have been carried further, by means
of improved instruments and methods suggested during
the progress of the work, but it was found necessary to
terminate the survey, at least in the meantime, and to
review what had been accomplished. We are conscious
of many shortcomings.

In conclusion, we tender our best thanks to all who
have assisted us in carrying these investigations to a
successful conclusion.

JOHN MURRAY.
LAURENCE PULLAR.

CHALLENGER OFFICE, EDINBURGH,
February 1910.

CONTENTS

VOLUME I

PAGE

Titles ........ i

Dedication ........ v

Preface, by Sir JOHN MURRAY and Mr LAURENCE PULLAR . vii

Contents of each Volume ...... ix

Statistical Tables of the Scottish Fresh-water Lochs, I. to VI. . xvii

Index to the Descriptions and Maps of the Scottish Fresh-water

Lochs sounded by the Lake Survey . . . xlv

Introduction, Methods, Instruments, and various Appendices, by

Sir JOHN MURRAY, K.C.B., F.R.S., D.Sc., etc. . . 1

Seiches and other Oscillations of Lake-surfaces, observed by the
Scottish Lake Survey, by Professor GEORGE CHRYSTAL, M.A.,
Sec. R.S.E., etc. ...... 29

Temperature of Scottish Lakes, by E. M. WEDDERBURN, M.A.,

LL.B., W.S., F.R.S.E. ..... 91

Chemical Composition of Lake-waters, by W. A. CASPARI, B.Sc.,

Ph.D., F.I.C. . . . . . .145

An Epitome of a Comparative Study of the Dominant Phanero-
gamic and Higher Cryptogamic Flora of Aquatic Habit, in
seven Lake Areas in Scotland, by GEORGE WEST . 1 56

Deposits of the Scottish Fresh-water Lochs, by W. A. CASPARI,

B.Sc., Ph.D., F.I.C. ...... 261

Biology of the Scottish Lochs, by JAMES MURRAY, F.R.S.E. —

I. The Biology in relation to Environment . . .275

II. Census of the Species . . . . .313

Some Distinctive Characters in the Fresh-water Plankton from
various Islands off the Xorth and West Coasts of Scotland,
by JOHN HEWITT, B.A. . . . 335

ix

x CONTENTS

PAGE

On the Nature and Origin of Fresh-water Organisms, by

WM. A. CUNNINGTON, M.A., Ph.D. . . . . 354

Summary of our Knowledge regarding various Limnological Pro-
blems, by C. WESENBERG-LUND, Ph.D. . . . 374

The Scottish Lakes in relation to the Geological Features of
the Country, by B. N. PEACH, LL.D., F.R.S., etc., and
JOHN HORNE, LL.D., F.R.S., etc. . .439

Characteristics of Lakes in general, and their Distribution over
the Surface of the Globe, by Sir JOHN MURRAY, K.C.B.,
F.R.S., D.Sc., etc. . . . . .514

Bibliography of Limnological Literature, compiled in the

Challenger Office by JAMES CHUMLEY . . . 659

Index of Genera and Species . . . .754

General Index ....... 765

VOLUME II

Titles . i

Dedication ........ v

Preface, by Sir JOHN MURRAY and Mr LAURENCE PULLAR . . vii

Contents of each Volume ..... ix

Statistical Tables of the Scottish Fresh-water Lochs, I. to VI. . xvii
Index to the Descriptions and Maps of the Scottish Fresh-water

Lochs sounded by the Lake Survey . . . xlv

PART I

Descriptions of Scottish Fresh-water Lochs, the maps of which, showing
the land-contours in shades of brown and the lake-contours in
shades of blue, are bound in Volumes III. and IV. : —

PAGE

Lochs of the Forth Basin ..... 1

Lochs of the Tay Basin ... .53

Lochs of the Inver Basin . . . .148

Lochs of the Roe Basin . . 156

Lochs of the Kirkaig Basin . . 159

Lochs of the Polly Basin . .168

Lochs of the Garvie Basin . . .172

Lochs of the Morar Basin . .195

Lochs of the Ewe Basin . . .210

Lochs of the Shiel Basin . .241

Lochs of the Ailort Basin ..... 249
Lochs of the nan Uamh Basin 253

CONTENTS xi

PAGE

Lochs of the Conon Basin . . . .261

Lochs of the Shin Basin . . 293

Lochs of the Naver Basin . . . . 309

Lochs of the Borgie Basin . . . . .316

Lochs of the Kinloch Basin . .321

Lochs of the Hope Basin .... 324

Lochs of the Beauly Basin . . . 334

Lochs of the Lochy Basin . . 355

Lochs of the Ness Basin 379

PART II

Descriptions of Scottish Fresh-water Lochs, the maps of which, showing
only the lake-contours in shades of blue, are bound in Volumes V.
and VI. :—

PAGE

Lochs of the Brora Basin .... 1

Lochs of the Helmsdale Basin .... 4

Lochs of the Wick Basin . ... 14

Lochs of the Wester Basin . . . . .17

Lochs of the Heilen Basin . ... 17

Lochs of the Dunnet Basin . . . . .18

Lochs of the Thurso Basin ... 19

Lochs of the Forss Basin . . . . .20

Lochs of the Laxford Basin . . . . .24

Lochs of the Scourie Basin . . . . .30

Lochs of the Badcall Basin . 32

Lochs of the Duartmore Basin . . . .34

Lochs of the Broom Basin . . 37

Lochs of the Gruinard Basin .... 40

Lochs of the Gairloch Basin . 49

Lochs of the Torridon Basin . . . . .58

Lochs of the Carron Basin ... 60

Lochs of the Alsh Basin . . . . .63

Lochs of the Aline Basin . . 65

Lochs of the Leven Basin . . 68

Lochs of the Oban Basin . . . . .73

Lochs of the Feochan Basin . . . . .74

Lochs of the Seil Basin . 77

Lochs of the Melfort Basin .... 78

Lochs of the Eachaig Basin . . 87

Lochs of the Doon Basin . . 91

Lochs of the Girvan Basin . . . . .96

Lochs of the Stinchar Basin . ... 98

Lochs of the Ryan Basin . . 99

xii CONTENTS

PAGE

Lochs of the Galdenoch Basin . . . .101

Lochs of the Luce Basin . .103

Lochs of the Bladenoch Basin . . . .106

Lochs of the Cree Basin ... 109

Lochs of the Fleet Basin . . . .113

Lochs of the Dee (Kirkcudbright) Basin . . . 114

Lochs of the Urr Basin . . . .123

Lochs of the Nith Basin . 126

Lochs of the Annan Basin . . . .129

Lochs of the Tweed Basin . . . .134

Lochs of the Monikie Basin . . . . .141

Lochs of the Lunan Basin . . . . .143

Lochs of the Dee (Aberdeen) Basin . . . .145

Lochs of the Spey Basin . . . . .152

Lochs of the Lossie Basin . . . .162

Lochs of the Findhorn Basin . . . . 1 64

Lochs of the Nairn Basin . . . . .167

Reservoirs of the Forth Basin . . . . .250

Lochs of the Clyde Basin . ... 262

Lochs of the Etive Basin . . . . .270

Lochs of Bute ....... 84

Lochs of Lismore . . . . .171

Lochs of Mull .... 173

Lochs of Benbecula . . . . . .177

Lochs of North Uist . . . . . .183

Lochs of Lewis . . . . . .205

Lochs of Orkney .... . 222

Lochs of Shetland 231

VOLUME III

Titles .... i

Dedication ....... v

Preface, by Sir JOHN MURRAY and Mr LAURENCE PULLAR . . vii

Contents of each Volume ...... ix

Statistical Tables of the Scottish Fresh-water Lochs, I. to VI. . xvii
Index to the Descriptions and Maps of the Scottish Fresh-water

Lochs sounded by the Lake Survey . . . xlv

Maps of the Lochs in the Basins of the Forth, Tay, Inver, Roe, Kirkaig,

Polly, Garvie, Morar, and Ewe : —

Lochs of the Forth Basin . . Plates I. to XI.

Lochs of the Tay Basin . . Plates XII. to XXXIV.

CONTENTS xiii

Lochs of the Inver Basin . Plates XXXV. and XXXVI.

Lochs of the Roe Basin . Plate XXXVII.

Lochs of the Kirkaig Basin . Plate XXXVIII.

Lochs of the Polly Basin . Plate XXXIX.

Lochs of the Garvie Basin . Plates XL. to XLII.

Lochs of the Morar Basin . Plates XLIII. to XLV.

Lochs of the Ewe Basin Plates XLVI. to LI.

VOLUME IV

PAGE

Titles ........ i

Dedication ........ v

Preface, by Sir JOHN MURRAY and Mr LAURENCE PULLAR . . vii

Contents of each Volume ...... ix

Statistical Tables of the Scottish Fresh- water Lochs, I. to VI. . xvii
Index to the Descriptions and Maps of the Scottish Fresh-water

Lochs sounded by the Lake Survey . . . xlv

Maps of the Lochs in the Basins of the Shiel, Ailort, nan Uamh, Conon,
Shin, Naver, Borgie, Kinloch, Hope, Beauly, Lochy, and Ness : —

Lochs of the Shiel Basin . Plates LII. to LIV.

Lochs of the Ailort Basin . Plate LV.

Lochs of the nan L'amh Basin . Plate LVI.

Lochs of the Conon Basin . Plates LVII. to LXIV.

Lochs of the Shin Basin Plates LXV. to LXX.

Lochs of the Xaver Basin Plates LXXI. to LXXIII.

Lochs of the Borgie Basin Plates LXX IV. and LXXV.

Lochs of the Kinloch Basin . Plate LXXVI.

Lochs of the Hope Basin . Plate LXXVII.

Lochs of the Beauly Basin . Plates LXXVIII. to LXXXII.

Lochs of the Lochy Basin . Plates LXXXIII. to XC.

Lochs of the Ness Basin Plates XCI. to CV.

VOLUME V

PAGE

Titles .......... i

Dedication ........ v

Preface, by Sir JOHN MURRAY and Mr LAURENCE PULLAR . vii

Contents of each Volume ...... ix

Statistical Tables of the Scottish Fresh- water Lochs, I. to VI. . xvii
Index to the Descriptions and Maps of the Scottish Fresh-water

Lochs sounded by the Lake Survey . • xlv

XIV

CONTENTS

Maps of the Lochs in the Basins of the Brora, Helmsdale, Wick,
Wester, Heilen, Dunnet, Thurso, Forss, Laxford, Scourie, Badcall,
Duartmore, Broom, Gruinard, Gairloch, Torridon, Carron, Alsh,
Aline, Leven, Oban, Feochan, Seil, Melfort, Eachaig, Doon,
Girvan, Stinchar, Ryan, Galdenoch, Luce, Bladenoch, Cree, Fleet,
Dee (Kirkcudbright), Urr, Nith, Annan, Tweed, Monikie, Lunan,
Dee (Aberdeen), Spey, Slains, Lossie, Findhorn, and Nairn ; and
in the Islands of Bute, Lismore, and Mull : —

Lochs of the Brora Basin

Lochs of the Helmsdale Basin

Lochs of the Wick Basin

Lochs of the Wrester Basin

Lochs of the Heilen and Dunnet

Basins ....
Lochs of the Thurso Basin
Lochs of the Forss Basin
Lochs of the Laxford Basin .
Lochs of the Scourie Basin .
Lochs of the Badcall Basin .
Lochs of the Duartmore Basin
Lochs of the Broom Basin
Lochs of the Gruinard Basin .
Lochs of the Gairloch Basin .
Lochs of the Torridon Basin .
Lochs of the Carron Basin
Lochs of the Alsh Basin
Lochs of the Aline Basin
Lochs of the Leven Basin
Lochs of the Oban and Feochan

Basins ....
Lochs of the Seil and Melfort Basins
Lochs in the Island of Bute .
Lochs of the Eachaig Basin .
Lochs of the Doon Basin
Lochs of the Girvan and Stinchar

Basins ....
Lochs of the Ryan Basin
Lochs of the Galdenoch and Luce

Basins ....
Lochs of the Bladenoch Basin
Lochs of the Cree Basin
Lochs of the Urr Basin
Lochs of the Dee (Kirkcudbright)

Basin

Plate I.
Plate II.
Plate III.
Plate IV.

Plate V.

Plate VI.

Plate VII.

Plates VIJI. to X.

Plate XI.

Plate XII.

Plate XIII.

Plates XIV. and XV.

Plates XVI. and XVII.

Plates XVIII. and XIX.

Plate XX.

Plates XXI. and XXII.

Plates XXIII. and XXIV.

Plate XXV.

Plates XXVI. and XXVII.

Plates XXVIII. and XXIX.

Plates XXX. and XXXI.

Plate XXXII.

Plate XXXIII.

Plates XXXIV. to XXXVL

Plate XXXVII.
Plate XXXVIII.

Plate XXXIX.
Plates XL. and XLI.
Plate XLII.
Plate XLIII.

Plates XLIV. and XLV.

CONTENTS

XV

Lochs of the Fleet and Nith Basins .
Lochs of the Annan Basin
Lochs of the Tweed Basin
Lochs of the Monikie Basin .
Lochs of the Lunan Basin
Lochs of the Dee (Aberdeen) Basin .
Lochs of the Slains and Lossie Basins
Lochs of the Spey Basin
Lochs of the Findhorn Basin .
Lochs of the Nairn Basin
Lochs in the Island of Lismore
Lochs in the Island of Mull .

Plate XLVI.

Plate XLVII.

Plates XLVIII. and XL1X.

Plate L.

Plate LI.

Plates LII. to LIV.

Plate LV.

Plates LVI. to LXI.

Plates LXII. and LXIII.

Plate LXIV.

Plate LXV.

Plates LXVI. and LXVII.

VOLUME VI

PAGE

i

Titles ........

Dedication ........ v

Preface, by Sir JT>HN MURRAY and Mr LAURENCE PULLAR . . vii

Contents of each Volume ...... ix

Statistical Tables of the Scottish Fresh-water Lochs, I. to VI. . xvii
Index to the Descriptions and Maps of the Scottish Fresh- water

Lochs sounded by the Lake Survey . . . xlv

Maps of the Lochs in the Islands of Benbecula, North Uist, Lewis,
Orkney, and Shetland ; and in the Basins of the Etive and Clyde ;
and of the Reservoirs in the Forth Basin : —

Lochs in the Island of Benbecula
Lochs in the Island of North Uist
Lochs in the Island of Lewis .

Lochs in the Orkney Islands .
Lochs in the Shetland Islands .
Reservoirs of the Forth Basin .
Lochs of the Etive Basin

Lochs of the Clyde Basin

Plates LXVIII. and LXIX.
Plates LXX. to LXXVII.
Plates LXXVIII. to

LXXXIX.

Plates XC. to XCIV.
Plates XCV. to CVI.
Plates CVII. to CXVIII.
Plates CXXIL, CXXIIL,

CXXVI. to CXXXI.
Plates CXXIV., CXXV.,

CXXXII. to CXXXIV.

In addition to the maps showing the depths of the
lochs, the following maps are included in Vol. III. :—

Plate I. Head-waters of the Forth — Orography and drainage areas.

Plate II. „ ., „ — Surface geology.

Plate III. „ „ „ —Mean annual rainfall.

Plate XIV. Temperature Section of Loch Ericht.

Plate XXXIV. Head- waters of the Tay — Surface geology.

Plate XLI1. Assynt District — Surface geology.

Plate LI. Loch Maree District — Surface geology.

STATISTICAL TABLES OF THE
SCOTTISH FRESH-WATER LOCHS

(Surveyed during the years 1897 to 1909)

DURING the course of the Lake Survey work 562 of the Scottish
fresh-water lochs were surveyed. These include all the principal
lochs of the country, and a very large number of the smaller and less
important ones. As a matter of fact, all lochs were surveyed on
which boats could be found at the time the work was being carried
out. To have included all the smaller highland and less accessible
lochs and tarns would have very greatly increased the expense and
the time involved. To transport a boat to many of the remote
lochs in the Highlands would have entailed much labour and
difficulty, not to speak of the objections of proprietors, keepers, and
others, who do not wish to have grouse moors and deer forests dis-
turbed at a time of the year when the lochs are most accessible.

The general results of the survey work are, however, in no way
affected by these smaller lochs having been excluded, for a great
many lochs have been surveyed in all districts of the country.

The following tables are intended to summarise the results which
are given in detail in Volume II. of this Report.

Table I. shows the lakes arranged according to their lengths.

Table II. shows the lakes arranged according to their superficial
areas.

Table III. shows the lakes arranged according to their maximum
depths.

Table IV. shows the lakes arranged according to their mean
depths.

Table V. shows the lakes arranged according to the volume of
water in each.

Table VI. shows :—

(a) The number of lakes surveyed in the various river basins ;

(b) The number of soundings taken in the lakes of the various

river basins ;

xvii b

xviii THE FRESH- WATER LOCHS OF SCOTLAND

(/•) The volume of water in the lakes of the various river basins
in millions of cubic feet ;

(d) The superficial area of the lakes in the various river basins ;

(e) The extent of the drainage area in the various river basins,

together with the ratio of the drainage area to the super-
ficial area of the lakes.

The information in Table VI. is extracted from the tables given in
greater detail in the descriptions which will be found in Volume II.
of this Report.

From this table it will be seen that 562 lochs have been surveyed,
and that the number of soundings recorded on the maps of these lochs
is 59,195. The actual number taken exceeds 60,000. The aggregate
area of the water-surface is over 340 square miles, and therefore the
average number of soundings per square mile of surface is 174.

The aggregate volume of water contained in these 562 lochs is
estimated at about 1,015,814 millions of cubic feet, or nearly 7 cubic
miles. The area drained by the lochs is about 6669 square miles, or
about 19 J times the area of the lochs.

STATISTICAL TABLES

xix

TABLE I

FRESH-WATCH LOCHS OF SCOTLAND (SOUNDED BY THE LAKE SURVEY)
ARRANGED ACCORDING TO LENGTH

Loch.

Length.
Miles.

Loch.

Length.
Miles.

1. Awe (Etive)

25-47

55. Beoraid ....

3-43

2. Xess ....

24-23

56. Dun na Seilcheig

3-41

3. Lomond ....

22-64

57. Eilt ....

3-37

4. Shiel ....

17-40

58. na Meide ....

3-33

5, Shin ....

17-22

59. Avich ....

330

6. Tav

14-55

60. Stack ....

3-27

7. Ericht ....

14-50

61. Afiric ....

3-20

8. Maree ....

13-46

62. Ossian ....

3-20

9. Arkaig ....

1200

63. Skinaskink

3-16

10. Morar ....

11-68

64. Cliff ....

3'16

11. Lochy ....

978

65. Coir' an Fhearna

3-15

12. Rannoch ....

9-70

66. Ba(Mull)

3-04

13. Katrine ....

8 00

67. Obisary ....

3-03

14. Langavat (Lewis)

7-86

68. Merkland

3-02

15. Lag^an ....

7-04

69. St Mary's

3-02

16. Quoich ....

6-95

70. nan Cuinne

3-00

17. Fannich ....

6-92

71. Watten ....

3-00

18. Earn .

6'46

72. Trealaval ....

2-90

19. Assynt ....

6-36

73. Cam ....

276

20. Naver ....

6'18

74. Loyne (East) .

2-75

21. Hope ....

6-13

75. Tummel .

2-75

22. Eck

6-02

76. Suainaval ....

2-68

23. Fionn (Gruinard)

576

77. a' Bhraoin

2-66

24. Boon ....

5-64

78. Beinn a' Mheadhoin .

2-64

25. Laidon ....

5-30

79. nan Eun (N. Uist) .

2-63

26. Treig ....

5-10

80. Fadagoa ....

2-60

27. Luichart ....

5-05

81. Garry (Tay)

2-55

28. Garrv(Ness) .

4-90

82. Strom ....

2-54

29 Mhor ....

4-84

83. Tulla ....

2-50

30. Harrav ....

4-84

84. Talla ....

2-47

31. Ken

4-62

85. Fionn (Kirkaig)

2-40

32. Frisa ....

4-50

86. nan Geir^ann (Mill) .

2-39

33. Scadavay (East)

4'50

87. Calder ....

2-32

34. Laoghal ....

4-46

88. Morie ....

2'30

35. Clunie (Xess) .

4-28

89. Ard ....

2-30

36. Mullardoch

4-16

90. Grunavat.

2-26

37. More (Laxford)

4-11

91. Ruthven ....

2-26

38. Monar ....

4-10

92. Muick ....

2-22

39. Veyatie ....

4-05

93. Langavat (Benbecula)

2-20

40. Glass ....

4-03

94. Lochindorb

2-18

41. Expansions of River Dee .

4-02

95. Ba(Tay) ....

2-15

42. Oich ....

4-02

96. Bad a' Ghaill .

2-13

43. Vennachar

4-00

97. Boardhouse

2 03

44. Luhnaig ....

4-00

98. Grennoch.

2-02

45. Damh (Torridon)

3-93

99. Dhughaill (Carron) .

2'02

46. Lurgain ....

3-87

100. Skebacleit

2-00

47. Scadavay (West)
48. Stenness ....

3-80
379

101. Swannay ....
102. Elide Mor

2-00
1-98

49. na Sheallag

374

103. Migdale ....

1-92

50. Fada (Ewe)

3-74

104. na Salach Uidhre .

•90

51. Leven ....

3-65

105. Urigill ....

•86

52. Brora ....

3-53

106. Beannachan

•85

53. Voil ....

3-50

107. Arienas ....

•85

54. a' Chroisg

3-47

108. Achall ....

•83

xx THE FRESH-WATER LOCHS OF SCOTLAND

TABLE I — continued

Loch.

..ength.
Miles.

Loch.

Length.
Miles.

109. na h-Earba (West) .

1-80

169. Shurrery ....

1-28

110. Fada (N. Uist) .

1-80

170. Harperrig

1-27

111. Woodhall.

179

171. Buidhe (Fleet) .

1-27

112. a' Bhealaich (Gairloch)

1-78

172. na h-Earba (East) .

1-27

113. Thorn ....

1 -78

173. Hunder ....

1-26

114. Lyon ....

1-74

174. Kirbister ....

1-26

115. Freuchie ....

1-74

175. Bunacharan

1-26

116. nah-Oidhche .

1-73

176. ant-Seilich

1-26 i

117. Castle Seraple .

172

177. Martnaham

1-26

118. Eye

1-72

178. Achray ....

1-25

119. an Daimh (Shin)

1-71

179. Rescobie ....

1-24

120. Baddanloch

1-70

180. Beannach (Inver)

1-24

121. Chon (Forth) .

170

181. Urrahag ....

1-24

122. Nell

1-68

182. Loch ....

I -23

123. Trool ....

1-68

183. Droma ....

1-23

124. Heouravay

1-68

184. Dubh (Gruinard)

1-23

125. Leum a' Chlamhain .

1-62

185. Muckle Water .

1-21

126. Fiodhaig ....

1-61

186. an Gead ....

1-21

127. Heilen ....

1-60

187. Sloy ....

1-21

128. Olavat ....

1-60

188. Lowes (Tay) .

1-20

129. Fad

1-60

189. Castle (Bladenoch) .

1-20

130. Menteith ....

1-60

190. Inbhir ....

1-20

131. Ashie ....

1-60

191. Maberry ....

1-19

132. a' Bhealaich (Naver)

1-60

192. Dee

1-18

133. a' Bhaid-Luachraich .

1-57

193. a' Bharpa

1-18

134. Creagach ....

1-57

194. Garbhaig ....

1-18

135. Owskeich ....

1-56

195. an Duin (Spey)

I'M

136. Gladhouse

1-56

196. Tralaig ....

116

137. an Dithreibh .

1-55

197. an Strom ore

1-15

138. Scamadale

1-54

198. na Leitreach

1-14

139. an Ruathair

1-54

199. Oban nam Fiadh

I'M

140. Garve ....

1'54

200. Sgamhain

1-12

141. a' Chlair (Helmsdale)

1-53

201. Calavie ....

1-12

142. Fada (Gruinard)

1-52

202. Killin ....

1-12

143. Mochrum ....

1-50

203. nam Breac

1-12

144. a' Ghriama

1-50

204. an Eilein (Spey)

1-10

145. Threipmuir

1-50

205. Milton ....

1-10

146. Girlsta ....

1-48

206. Meiklie ....

1-10

147. Finlas ....

1-46

207. Auchenreoch

1'08

148. Poulary ....

1-46

208. Forfar ....

1-07

149. an Tomain

1-45

209. Crogavat ....

1-06

150. Caravat ....

1-45

210. Kinord

1-06

151. Lungard ....

1-44

211. Benachally

1.05

152. Dilate ....

1-43

212. a'Bhaillidh .

1-04

153. an Duin (N. Uist) .

1-40

213. Turret ....

1-04

154. Crocach . .

1-40

214. More Barvas

1-04

155. Gorm Loch Mor

1-39

215. Gartmorn ....

1-04

156. Glair (Ewe)

1-38

216. Insh ....

T03

157. Lintrathen

1-38

217. Moy ....

1-03

158. Black (Ryan) .

1-36

218. Borralan ....

1-03

159. Strandavat

1-36

219. Pattaek ....

1-03

160. a' Chuilinn (Conoii) .

1-35

220. Morlich ....

1-02

161. lubhair ....

1-35

221. Tingwall ....

1-02

162. Kernsary ....

1-35

222. an Staca ....

1-02

163. Coulin(Ewe) .

1-33

223. ic Colla ....

i-oo

164. Kilbirnie ....

1-32

224. na Craobhaig .

i-oo

165. Spiggie
166. Hundland

1-30
1-30

225. Vatandip ....
226. Gainmheich (South) .

i-oo
i-oo

167. Knockie ....

1'30

227. Wester ....

1-00

168. Loyne(West) .

1-28

228. Drunkie ....

i-oo

STATISTICAL TABLES

TABLE I — continued

XXI

Loch.

Length.
Miles.

Loch.

Length.
Miles.

229. Arklet ....

i-oo

289. na Creige Duibhe

0-80

230. Doine ....

I'OO

290. na Moracha

0-80

231. an Lagain

1-00

291. Kindar ....

0-80

2:32. Skaill ....

0-98

292. Builg ....

0-80

233. Skene(Dee)

0-98

293. Kirk Dam

0-80

•231. na Beinne Baine

0-97

294. Cro Criosdaig .

0-80

235. Bodavat ....

0-96

295. Eela

079

236. Cuil na Sithe .

0-96

296. Chaluim ....

0'78

237. Daimh (Tay) .

0-96

297. Skiach ....

0*78

238. Ailsh ....

0-95

298. Hempriggs

077

239. Cuil Airidh a' Flod .

0-94

299. Lochrutton

077

240. Alvie ....

0-94

300. Airidh na Lie .

0-76

241. Gryfe ....

0-94

301. Raoinavat

076

242. na Cuaich

0-94

302. Gelly ....

076

243. Con (Tay)
244. Dungeon ....

0-94
0-93

303. Lundie (Garry)
304. na Moine Buige

076
076

245. Skealtar ....

0-93

305. Araich-Lin

075

246. Clousta ....

0-92

306. an Laig Aird .

074

247. Dubh (Gahioch)

0-92

307. Davan ....

074

248. Xant ....

0-90

308. nam Breac Dearga .

074

1 249. Tollie ....

0-90

309. Muckle Lunga .

074

250. Hermidale

0-90

310. nan Deaspoirt .

074

251. Huna ....

0-90

311. Bran ....

074

252. Bradan ....

0 90

312. Howie ....

074

253. Fitty .

0-90

313. a' Ghobhainn .

073

254. Peppermill

0-90

314. Druim Suardalain .

073

255. North-house

0-90

315. na Lairige

073

256. Oehiltree ....

0-89

316. Stacsavat.

072

•257. White (Ryan) .

0-88

317. an Drainc

072

258. Ceo-Glas

0-88

318. Skeen (Annan)

072

259. Allt an Fhearna

0-88

319. Sguod ....

072

260. Eigheach ....

0-88

320. Broom ....

072

261. Achilty ....

0-87

321. Skerrow ....

070

262. Tankerness

0-86

322. na Bi

070

263. More (Thurso) .

0-86

323. Eileach Mhic' illeRiabbaich

070

264. a' Bhaid Daraich

0-86

324. Tearnait ....

070

265. Crombie Den .

0-86

325. Syre ....

070

266. Lunn da-Bhra .

0-86

326. Gaol na Doire .

070

267. Drumellie

0-86

327. Long ....

070

268. a' Mhuillin

0-84

328. nan Lann

070

269. Vaara ....

0-84

329. Carlingwark

070

270. Achanalt ....

0-84

330. Benisval ....

070

271. Callater ....

0-84

331. Bad an Sgalaig

0-69

Lowes (Tweed)

0'84

332. Spynie ....

0-69

273. Obau a; Chlachain .

0-84

333. Tartf ....

0-69

274. Ussie ....

0-84

334. Tormasad.

0-69

275. Lindores ....

0-84

335. Seil

0-68

276. Scarmclate

0-84

336. Ghuiragarstidh

0-68

Triud air Sgithiche .

0-84

337. Baile a' Ghobhainn .

0-68

278. a' Bhuird

0-84

338. Crunachau

0-68

279. na Moine

0-83

339. Rosebery ....

0'68

280. Castle (Annan) .

0-83

340. Drummond

0-68

Braigh Horrisdale .

0-82

341. Kennard .

0-68

282. Ghuilbinn

0-82

342. Deoravat ....

0-68

283. na h-Achlaise .

0'82

343. Clings ....

0-68

284. St John's.

0-82

344. na h- Airidh Sleibhe .

0-68

285. Awe(Inver) .

0-82

345. Dornal ....

0-68

286. Giorra ....

0-82

346. Bogton ....

0-66

287. an Tuirc ....

0-81

347. Portmore ....

0-66

288. Linlithgow

0-80

348. an Eilein (Gairloch) .

0-66

xxii THE FRESH- WATER LOCHS OF SCOTLAND

TABLE I— continued

Loch.

Length .
Miles.

Loch.

Length.
Miles.

349. a' Bhealaich (Alsh) .

0-66

409. Whinyeon

0-56

350. Stormont ....

0-66

410. a' Chonnachair

0-56

351. Morsgail ....

0'66

411. an Nostarie

0'56

352. Dibadale ....

0-66

412. Whitefield

0-56

353. an t-Slagain

0-65

413. na Ceithir Eileana .

0-56

354. Ordie ....

0'64

414. Sron Smeur

0-56

355. Gleann a' Bhearraidh

0-64

415. Gown (South) .

0-55

356. Grass ....

0-64

416. Moraig ....

0'55

357. Raonasgail

0'64

417. Monzievaird

0-55

358. Sealbhag ....

0-64

418. Coire nam Meann

0-54

359. Bosquoy ....

0-64

419. Kilconquhar

0-54

360. Valtos ....

0-64

420. na Stainge

0-54

361. Beannach (Gruinard)

0-63

421. a' Mhiotailt

0-54

362. Arthur ....

0-63

422. Bruadale ....

0-54

363. Edgelaw ....

0-62

423. Asta . . ...

0-53

364. Bad a' Chrotha

0-62

424. LTanagan ....

0-52

365. Roer ....

0-62

425. Burga ....

0-52

366. Craggie ....

0-62

426. Allan ....

0-52

367. na Deighe fo Dheas .

0-62

427. an Losgainn M6r

0-52

368. Allt na h-Airbhe

0'62

428. Kemp

0-52

369. Doire nam Marc

0-62

429. Monk Myre

0-52

370. an Laghair

0-62

430. nan Druimnean

0-52

371. Dochart ....

0-62

431. Lochinvar

0-52

372. Fiart ....

0-62

432. Flugarth ....

0-52

373. an Tachdaidh .

0-62

433. a' Bnaille

0-52

374. Clunie (Tay) .

0-62

434. na Coinnich

0-51

375. Urr

0-62

435. an Leoid ....

0-50

376. Dochard ....

0-62

436. an t-Seasgain .

0-50

377. Scaslavat ....

0-62

437. Aithness ....

0-50

378. a' Chlachain (Lewis)

0-62

438. Balgavies.

0-50

379. Black (Etive) (East) .

0-62

439. Bnrntisland .

0-50

380. nam Faoileag .
381. Leitir Easaich .

0-62
0-61

440. Havperleas
441. Eldrig ....

0-50
0-50

382. a' Choire ....

0-61

442. Littlester.

0-50

383. Harelaw ....

0-60

443. Kilcheran

0-50

384. an Droighinn .

0-60

444. na Doire Daraich

0-50

385. Leodsay ....

0-60

445. Tarruinn an Eithir .

0-50

386. Isbister ....

0-60

446. na Sreinge

0-50

387. Burraland

• 0-60

447. Mhic' ille Riabhaich

0-49

388. Sabiston ....

0-60

448. Hosta ....

0-49

389. Snarravoe

0'60

449. Breaclaich

0-49

390. Ederline ....

0-60

450. Peerie ....

0-48

391. Airidh na Ceardaich

0-60

451. a' Chlachain (Nairn)

0-48

392. Dhomhnuill Bhig .

0-60

452. nan Eun (Ness)

0'48

393. an lasgaich

0-59

453. Monikie (South)

0-48

394. Lochaber ....

0-59

454. Punds ....

0-48

395. Derculich.

0-59

455. na Craige

0-48

396. Bhradain ....

0-58

456. a' Ghlinne Dorcha .

0-47

397. nan Gabhar

0-58

457. Moor Dam

0-47

398. Phitiulais

0-58

458. Lundie (Cluriie)

0-46

399. Craiglush.

0-58

459. Shechernich

0-46

400. Butterstone

0-58

460. Liath ....

0'46

401. Veiragvat

0-58

461. Essan ....

0-46

402. Derclach ....

0'58

462. Fithie ....

0-46

403. Soulseat ....

0-58

463. a' Phearsain

0 46

404. Gown (North) .

0-57

464. nan Eun (Tay)

0-45

405. Black (Etive) (West)

0-56

465. a' Vullan

0-45

406. Black (Etive) (Mid) .

0-56

466. Rae

0-44

407. White of Myrton

0-56

467. Holl

0-44

408. Dhugaill (Torridon) .

0-56

468. an Duna ....

0-44

STATISTICAL TABLES

TABLE I — continued

xxm

Loch.

Length.
Miles.

Loch.

Length.
Miles.

469. Brow ....

0-44

517. Brough ....

0-32

470. Lochnaw ....

0-44

518. Geal

032

471. Dallas ....

0'43

519. Kilchoan (Upper) .

0-32

472. Mill

0-43

520. a' Chaoiuinn

0-32

473. Dubh(Ailort) .

0-43

521. Sior

0-32

474. Muck ....

0-42

522. na Garbh- Abhuinn Ard . 0'32

475. Clickhimin

0-42

523. Kinghorn. . . . 0'31

476. Harrow ....

0-4-2

524. a'Chladhaich . . . 0'31

477. Kirk ....

0-42

525. nan Losganan .

0-30

478. Monikie (North)

0-42

526. Hightae Mill .

0-30

479. Gamhna ....

0-42

527. Dubh-M6r

0-30

480. Lochenbreck .
481. nah-Ealaidh .

0-42
0-42

528. Beag ....
529. Sand ....

0-30
0-29

482. na Claise Fearna

0-42

530. Duartmore

0-29

483. nan Geireann .

0-41

531. Clubbi Shuns .

0-29

484. Lure ....

0'40

532. Hostigates

0-28

485. Sandy ....

0'40

533. Scoly ....

0-28

486. nan Garbh Chlachain

0-40

534. nan Rath ....

0-28

487. Bhac ....

0-38

535. Black (Tay) .

0-28

488. Broiiiter ....

0-38

536. Drumlamtbrd .

0-28

489. Fleet ....

0-38

537. nan Auscot

0-27

490. Hoglinns ....

0-38

538. na Creige Leithe

0-27

491. Collaster ....

0-38

539. Cults ....

026

492. na Beiste ....

0-37

540. Skae

0-26

493. Mama .

0-37

541. Cornish '.

0-26

494. Fyntalloch

0-37

542. Kirriereoch

0-26

495. Auchenchapel .

0-37

543. Eion Mhic Alabtair .

0-25

496. Birka ....

0-36

544. na Beithe

0-25

497. Aboyne ....

0-36

545. an Dubh (Lochy) .

0-24

498. na Garbh- Abhuinn .

0-36

546. an Tairbeirt Stuadhaich .

0-23

499. Hoil ....

0-36

547. Magillie ....

0-22

500. Blairs ....

0-36

548. Tutach ....

0-22

501. Gainmheich (North) .

0-36

549. Crann ....

0-22

502. a' Bhainne . . . 0'36

550. Setter ....

0-22

503. Kilchoan (Lower)

0-36

551. Pitlyal ....

0-21

504. Tilt

0-35

552. na Gealaich

0-21

505. Anna ....

0-35

553. Choire na Cloich

0'20

506. Aslaich ....

0-35

554. Dubh (Forth) .

0-20

507. Fingask ....

0-35

555. Loch on Eilean Subhainn

508. Dubh (Etive) .

0-35

(Maree)

0-18

509. Maol a' Choire .

0-34

556. Dubh (Ness) .

0-18

510. Laide ....

0-34

557. na h-Eaglais .

0-16

511. White (Tay, .

0'34

558. Uaine ....

0'14

512. Duddingston .

0-34

559. St Margaret's . .

0-13

513. Kinellan ....

0-33

560. Dhu (Portsonarhan) .

012

514. Fender ...

0-33

561. Allt na Mult .

0-12

515. Ree

0-32

562. Rainbow ....

o-io

516. Buidhe(Tav) .

032

XXIV

THE FKESH-WATER LOCHS OF SCOTLAND

TABLE II

FRESH-WATER LOCHS OF SCOTLAND (SOUNDED BY THE LAKE SURVEY)
ARRANGED ACCORDING TO SUPERFICIAL AREA

Loch.

Area.
Square
Miles.

Loch.

Area.
Square
Miles.

1. Lomond ....

27-45

54. nan Cuinne

1-15

2. Ness

21-78

55. Coir' an Fhearna

1-15

3. Awe (Etive)

14-85

56. Tulla ....

no

4. Maree ....

11-03

57. Clunie (Ness) .

1-10

5. Morar ....

10-30

58. Ossian ....

1-03

6. Tay

10-19

59. Bad a5 Ghaill .

1-02

7. Shin

8-70

60. Menteith ....

1-02

8. Shiel ....

7-56

61. Cam ....

1-01

9. Rannoch ....

7-37

62. a' Chroisg

1-00

10. Ericht ....

7-21

63. Stack ....

0-99

11. Arkaig ....

6-24

64. St Mary's.

0-99

12. Lochy ....

5-91

65. Baddanloch

0-99

13. Leven ....

5-30

66. Tummel ....

0-98

14. Katrine . . . . i 478

67. Lubnaig ....

0-96

15. Earn . . . .8*91

68. Ard

0-94

16. Harray ....

378

69. Swannay ....

0-94

17. Fanmch ....

3-60

70. Suainaval. . . . 0'94

18. Fionn (Gruinard) :

3-52

71. Veyatie . . . . ' 0'93

19. Langavat (Lewis)

3-45

72. Morie . . . . 0'92

20. Assynt ....

3-10

73. Ba(Tay) . . . . 0'92

21. Laggan ....

2-97

74. Boardhouse . . . 0*89

22. Quoich ....

2-86

75. Brora . . . . 0*88

23. Laoghal ....

2-55

76. Voil 0-88

24. Stenness ....

2-46

77. na Meide .... 0'87

25. Treig ....

2-41

78. Muick . . . . 0-85

26. Hope ....

2-35

79. Lochiudorb . . . 0'84

27. Naver ....

2-26

80. an Ruathair . . . 0'82

28. Skinaskink

2-09

81. Affric . . . . 0-82

29. Boon ....

2-04

82. Beinn a' 'Mheadhoin . 079

30. Dim na Seilcheig

1-95

83. Urigill . . . . 078

31. Glass ....

1-86

84. Oich .... 0-76

32. Laidon ....

1-80

85. anDithreibh . . . 0 74

33. Luichart ....

1-76

86. Fada (N. Uist) .

0-70

34. Garry (Ness) .

1-75

87. Merkland. . . . 0'69

35. Eck

1-70

88. nan Geireann (Mill) . . 0'68

36. Frisa ....

1-69

89. Expansions of River Dee . 0'67

37. Mhor ....

1-69

90. a' Bhraoin . . . 0'66

38. Vennachar

1-61

91. Arienas . . . .0'66

39. More (Laxford)

1-46

92. Eilt

0-66

40. Watten ....

1-45

93. Owskeich ....

0-65

41. Fada(Ewe)

1-44

94. Lintrathen

0-62

42. na Sheallag

1-37

95. Garry (Tay)

0-61

43. Ken

1-36

96. Trealaval ....

0-61

44. Damh (Torridon)

1-33

97. Grunavat ....

0-60

45. Calder ....

1-32

98. Gladhouse

0-59

46. Lurgain ....

1-26

99. Garve ....

0-59

47. Bca(Mull).

1-21

100. Fiodhaig ....

0-58

48. Avich ....

1-21

101. Caravat ....

0-58

49. Scadavay (West)
50. Mullardoeh

1-20
1-18

102. Ruthven ....
103. Beoraid ....

0-57
0'55

51. Monar .

1-17

104. Leum a' Chlamhain .

0-55

52. Obisary ....

1-17

105. na h-Oidhche .

0-54

53. a' Chlair (Helmsdale)

1-17

106. Freuchie ....

0-54

STATISTICAL TABLES

TABLE II— continued

XXV

Area.
Loch. Square
Miles.

Loch.

Area.
Square
Miles.

107. Achall . . . . 0-52

166. Heilen ....

0-30

108. nan Eun (N. Uist) . . 0'52

167. Skebacleit

0-30

109. Ashie . . . . 0'52

168. nah-Achlaise .

0"29

110. Thorn . . . . 0-52

169. Kinord ....

0-29

111. Strom . ! 0'52

170. a' Bhaillidh

0-29

112. a' Bhaid-Luachraich . . 0'51

171. Hunder ....

0-29

113. Nell 0 50

172. Truid air Sgithiche .

0-29

114. Fadagoa . . .1 0'48

173. Mov ....

0-29

115. Talla . . . ; 0'47

174. Gorm Loch Mor

0-29

116. Morlich . . . . i 0'47

175. More (Thurso) .

0-28

117. Scadavay (East) . . 0'46

176. Fad

0-28

11 N Creagach . . . . • 0'46

177. Knockie ....

0-28

119. Skene(Dee) . . . 0'46

178. Drumellie

0-27

120. Grennoch . . . 0'45

179. Pattack ....

0-27

121. Insh . . . . 0-44

180. an Daimh (Shin)

0-27

12-2. a' Bhealaich (Gairloch) . 0'44

181. Maberry ....

0-27

123. Dhughaill (Carron) . . 0'44

182. Benisval ....

0-27

124. Chon (Forth) . . . 0'43

183. Clubbi Shuns .

0-27

125. Loyne (East) . . . 0'43

184. a' Bhealaich (Naver)

0-27

126. Hundland . . . 0'43

185. Turret ....

0-26

127. Beannachan . . . 0'42

186. Calavie ....

0-26

1-JS. na h-Earba (West) . - C'41

187. Woodhall

0-26

129. Migdale . . . . 0'41

188. an Staea ....

0-26

130. a' Ghriama * . . . 0'40

189. Tollie ....

0-26

131. CM' . . . .0-40

190. Benachally

0-25

132. Dee 0'40

191. Crocach ....

0-25

133. an t-Seilich . . . 0'39

192. Achanalt.

0-25

134. Kilbirnie . . . . 0'39

193. Bunacharan

0-25

135. Ailsh . . . . 0-38

194. Rescobie ....

0-25

136. EildeMor . . . 0'38

195. Skaill . . ' .

0-24

137. na Salach Uidhre . . 0'38

196. Clair(Ewe)

0 24

13>. Lyon . . . . 0'37

197. na Beinne Baine

0-24

139. More Bar vas . . . 0'37

198. Milton ....

0-24

140. Castle (Bladenoch) . . ' 0'36

199. Ochiltree . . ...

0-24

141. Shurrery . . . . | 0'36

200. an Stromore

0-24

142. Mochrum . . . 0'36

201. Loyne (West) .

0-24

143. Harperrig . . . 0'35

202. Fada (Gruinard)

0-23

144. Scamadale . . . ' 0'3o

203. Davan ....

0-23

145. Girlsta . . . . 0'35

204. Ghuilbinn

0-23

146. Kirbister .... 0'35

205. na h-Earba (East) .

0-23

147. Lowes (Tay) . . . 0'34

206. Garbhaig ....

0-23

148. Luugard .... 0'34

207. Gelly ....

0-23

149. Hempriggs . . . 0'34

208. Achilty .

0-23

ir.i.i. Spiggie . . . . 0'34

209. White (Ryan) .

0-23

151. Arklet .... 0-33

210. Black (Ryan) .

0"23

152. Fioiin (Kirkaig) . . j 0'33

211. Tankerness

0-23

153. Eye i 0'33

212. Inbhir ....

0-23

154. Allt an Fhearna . . 0'33

213. Tralaig ....

0-23

155. Urrahag .... 0'33

214. Trool ....

0-23

156. Castle Semple . . . 0'32

215. Alvie ....

0-22

157. Aehrav . . . . 0'32

216. Olavat ....

0-22

Dubh (Gruinard) . . I 0*32

217. Drunkie ....

0-22

159. Meiklie . . . . : 0'31

218. Gartmorn

0-22

160. Kernsarv . . . . ' 0'31

219. Sgamhain

0-22

161. Ussir . . . . 0-31

220. Fitty ....

0-22

162. Scarmclate . . . 0'30

221. Finfas ....

0-22

163. Castle (Annan) . . 0'30

222. Dilate ....

0-22

164. St John's. . . . 0 30

223. nam Breac

0-22

165. Threipmuir . . . 0*30

224. Xant ....

0*22

xxvi THE FRESH-WATER LOCHS OF SCOTLAND

TABLE II — continued

Loch.

Area.
Square
Miles.

Loch.

Area.
Square
Miles.

225. Bad an Sgalaig

0-22

284. a' Ghobhainn .

0-15

226. Eela ....

0-22

285. an Tomain

0-15

227. Doine ....

0-21

286. Dubh (Gairloch)

0-15

228. Kindar ....

0'21

287. na Moracha

0-15

229. lubhair .

0-21

288. an Drainc

0-15

230. Huna ....

0-21

289. Chaluim ....

0-15

231. Gainmheich (South) .

0-21

290. Roer ....

0-15

232. Tarff ....

0-21

291. Lowes (Tweed) .

015

233. Clunie (Tay) .

0-21

292. Giorra ....

0'14

234. Strandavat

0-21

293. Pepper mill

0-14

235. Vaara ....

0-21

'z94. Drummond

0-14

236. Buidhe (Fleet) .

0-21

295. Oban nam Fiadh

0'14

237. Killin ....

0-20

296. an Nostarie

0-14

238. Lochrutton

0-20

297. anTachdaidh .

0-14

239. an Eilein (Spey)

0-20

298. an Eilein (Gairloch) .

014

240. Skealtar ....

0-20

299. Braigh Horrisdale .

0'14

241. na Craobhaig .

0-20

300. na Moine ....

0-14

242. Muckle Water .

019

301. Poulary ....

0-14

243. Coire nam Meann

019

302. Dungeon ....

0-14

244. Langavat ( Benbecula)

0'19

303. Clings ....

0-14

245. an Duin (N. Uist) .

0-19

304. Bodavat ....

0-14

246. Skerrow ....

0-19

305. Stacsavat ....

0'14

247. a' Bharpa

0'19

306. Broom ....

0-13

248. Araich-Lin

0'18

307. Bradan ....

0-13

249. na Cuaich

0-18

308. Isbister ....

0-13

250. Ordie ....

0-18

309. Loch ....

0-13

251. Gryfe ....

0-18

310. Heouravay

0-13

252. Coulin(Ewe) .

0-18

311. Awe (Inver)

0'13

253. a' Chuilinn (Conon) .

0-18

312. Auchenreoch .

0-13

254. Droma . .

0-18

313. Allt na h-Airbhe

0-13

255. Borralan . . . .

0-18

314. Crogavat ....

0-13

256. Martuaham

0-18

315. a'Choire ....

0-13

257. Beannach (Inver)

0'18

316. icColla ....

0-13

258. Daimh (Tay) .

0-17

317. an Laghair

0'13

259. Tearnait ....

0-17

318. a' Bhuird.

0-13

260. Wester ....

0-17

319. Dochard ....

0-13

261. an Gead ....

0-17

320. na Leitreach .

0-13

262. Syre ....

0-17

321. Cro Criosdaig .

0-13

263. Clousta ....

0-17

322. Kennard ....

0'12

264. Butterstoue

0-17

323. Burga ....

0-12

265. Sguod ....

0-17

324. Gaol na Doire .

0-12

266. a' Bhaid Daraich

0-17

325. Builg ....

0-12

267. Lindores ....

0-17

326. Stormont ....

0-12

268. Lundie (Garry)

0-17

327. Arthur ....

0-12

269. Dornal ....

0-17

328. an t-Slagain

0-12

270. Urr

0*17

329. a' Bhealaich (Alsh) .

0'12

271. Tingwall ....

0-17

330. Beannach (Gruinard)

0-12

272. Derculich ....

016

331. Sabiston ....

0-12 -

273. an Duin (Spey)

0-16

332. Druim Suardalain .

0-12

274. Long ....

0-16

333. Deoravat ....

0-12

275. Forfar ....

0-16

334. Monikie (South)

0-12

276. Linlithgow

0-16

335. Craiglush.

0-11

277. Portmore ....

0-16

336. Doire nam Mart

0-11

278. Whinyeon

0-16

337. Ounachan

O'll

279. Garlingwark

0-16

338. Callater ....

0-11

280. a' Mhuilinn

0-16

339. Sealbhag ....

0-11

281. nam Faoileag .

0-16

340. Skeen (Annan).

0-11

282. Skiach ....

0-15

341. an Duna ....

0-11

283. Kilconquhar

015

342. na h-Airidh Sleibhe .

0-11

STATISTICAL TABLES

TABLE II — continued

XXV11

Area.
Loch. Square
Miles.

Loch.

Area.
Square
Miles.

343. Ederline . . . . O'll

402. Veiragvat.

0-08

344. an Lagain . . . O'll

403. Burraland

0'08

345. Lochinvar

0-11

404. Valtos ....

0'08

346. Kemp ....

0-11

405. an Droighinn .

0'08

347. Soulseat . . . . O'll

406. Rosebery ....

0'08

348. an Leoid .... O'll

407. Balgavies.

0'08

349. Raoiuavat . . . O'll

408. Clickhimin

0-07

350. Bosquoy . . . . O'lO

409. Dochart ....

0-07

351. Con(Tay) . . . O'lO

410. Holl ....

0'07

352. Hosta ....

O'lO

411. Breaclaich

0'07

353. nah-Ealaidh .

o-io

412. Burntisland

0-07

354. na Ceithir Eileana .

O'lO

413. na Lairige

0-07

355. Morsgail ....

o-io

414. Oban a' Chlachain .

0'07

356. Liath ....

o-io

415. Shechernich

0'07

357. an Laig Aird .

o-io

416. na Doire Daraich

0-07

358. Phitiiifais

o-io

417. Sandy ....

0-07

359. Raonasgail

o-io

418. nan Gabhar

0-07

360. Littlester.

O'lO

419. Bad a' Chrotha

0'07

361. Bruadale ....

o-io

420. a' Chlachain (Lewis .

0-07

362. Vatamiip ....

O'lO

421. Craggie . .

0'07

363. Lunn da-Bhia .

o-io

422. AVhiteHeld

0-07

364. a' Phearsain

o-io

423. Eldrig ....

0'07

365. Sloy

o-io

424. Monikie (North)

0'07

366. Cuil Airidh af Flod .

O'lO

425. Gown (North) .

0'07

367. nan Lann

O'lO

426. Lochnaw ....

0'07

368. Eigheach ....

0'09

427. Dibadale ....

0'07

369. Spynie ....

0-09

428. Fleet ....

0-07

370. Ghuiragarstidh

0'09

429. Airidh na Lie .

0'07

371. nam Breac Dearga .

0'09

430. Brow ....

0-07

372. na Moine Bulge

0'09

431. Dhomhmiill Bhig .

0'07

373. Cuil na Sithe .

0'09

432. Howie. ....

0'07

374. a' Chlachain (Nairn)

0'09

433. Hoglinns ....

0'06

375. Gown (South) .

0-09

434. Auchenchapel .

0'06

376. Bogtou ....

0-09

435. Dallas ....

0-06

377. na Sreinge

0'09

436. Monzievaird

0'06

378. Funds ....

0'09

437. Aboyne ....

0-06

379. Xorth -house .

0 09

438. Hoil ....

0'06

380. Kirk Dam

0-09

439. Harperleas

0 06

381. nan Deaspoiit .

0'09

440. Moraig ....

0-06

382. Muckle Lunga .

0'09

441. Fingask ....

0'06

383. Aithness . . . . 0'09

442. an lasgaich

0'06

384. na Dei^he fo Dhtas . . 0'08

443. nan Eun (Tay)

0'06

3S5. Sron Smeur . . . 0'08

444. Tarruinn an Eithir .

0'06

386. Hermidale . . . 0'08

445. na Creige Duibhe

0'06

387. na Stainge

0'08

446. a' Chonnachair

0'06

388. a' Bhradain

0-08

447. Mhic' ille Riabhaich

0-06

389. Moor Dam

0'08

448. Laide ....

0'06

390. Leitir Ea<aich .

0'08

449. Dhugaill (Torridon) .

0-06

391. Lochaber ....

0'08

450. Flugarth ....

0'06

392. a' Mhiotaiit .

0-08

451. Black (Etive) (East) .

0'06

393. an Tuirc ....

0'08

452. Harrow ....

0'06

394. a' Ghlinne Dorcha .

0-08

453. Derclach ....

0'06

395. Seil

0-08

454. Crombie Den .

0-06

396. White of My rton . . 0'08

455. Peerie ....

0'06

397. Ceo-Glas . . . . 0'08

456. Airidh na Ceardaich

0'06

398. Leodsay . , . . 1 0'08

457. Gsinmheich (Xorth)

0'06

399. Scaslavat . . . . 0'08

458. na Bl

0'06

400. Tormasacl

0'08

459. nan Druimnean

0'06

401. Snarravoe

0'08

460. Lochenbreck

0'06

xxviii THE FRESH-WATER LOCHS OF SCOTLAND

TABLE II — continued

Loch.

Area.
Square
Miles.

Loch.

Area.
Square
Miles.

461. Black (Etive) (Mid) .

0'05

512. Tilt

0'03

462. ,, ,, (West)

0-05

513. Allan ....

0'03

463. Buidhe(Tay) .

0-05

514. Maol a' Choire .

0-03

464. Kinghorn

0-05

515. Tutach ....

0'03

465. Essan . . . .

0-05

516. Mama ....

0'03

466. Kirk ....

0-05

517. Kirriereoch

0'03

467. Bhac ....

0-05

518. Brough ....

0-03

468. Mill

0-05

519. Kilchoan (Lower) . . 0'03

469. Rae

0'05

520. a' Chaoruinn . . . 0'03

470. nan Garbh Chlachain

0'05

521. Hightae Mill .

0'03

471. Dubh(Ailort) .

0-05

522. Fithie ....

0'03

472. na Coinnich

0'05

523. Sior

0-03

473. Eileach Mhic' ille Riabhaich

0-05

524. na Beithe

0-03

474. na Garbh-Abhuinn .

0-05

525. a' Buaille ....

0'03

475. na Claise Fearna

0'05

526. Cults ....

0'03

476. Baile a' Ghobhainn .

0'05

527. na Garbh- Abhuiim Ard .

0-03

477. Asta ....

0-05

528. Skae ....

0-03

478. a' Bhainne

0'05

529. Aslaich ....

0-03

479. Harelaw ....

0'05

530. Dubh (Etive) .

0-03

480. Birka ....

0-05

531. Hostigates

0-03

481. nan Eun (Ness)

0-05

532. Duddingston .

0 03

482. an Losgainn Mor

0-05

533. Pitlyal ....

0'02

483. Dubh-Mor

0-05

534. Sand ....

0-02

484. Gleann a' Bhearraidh

0-05

535. White (Tay) .

0-02

485. Fiart ....

0'05

536. an t-Seasgain .

0'02

486. Edgelaw ....

0-05

537. Dubh (Forth) .

0-02

487. Grass ....

0-05

538. a5 Chladaich . . . \ 0'02

488. Lure ....

0'05

539. Scoly ....

0 02

489. na Craige ....

0-04

540. Crann ....

0-02

490. Blairs ....

0-04

541. Duartmore . . .0*02

491. Fender ....

0-04

542. Kinellan . . " . . 0'02

492. Anna ....

0-04

543. na Gealaich . . . 0'02

493. Monk Myre

0-04

544. Cornish . . . . 0'02

494. Eion Mine Alastair .

0-04

545. nan Rath . . . 0'02

495. na Beiste ....

0-04

546. Setter . . . . 0'02

496. nan Geireann .

0'04

547. Magillie . . . . 0'02

497. Beag ....

0-04

548. na h' Eaglais . . . 0'02

498. Kilcheran.

0-04

549. Black (Tay) . . . O'Ol

499. Lundie (Clunie)

0-04

550. nan Aiiscot . . . O'Ol

500. a' Vullan ....

0-04

551. Uaine .... O'Ol

501. Gamhna ....

0'04

552. an Tairbeirt Stuadhaich . O'Ol

502. Uanagan ....

0'04

553. Loch on Eilean Subhainn . O'Ol

503. Collaster ....

0-04

554. na Creige Leithe . . O'Ol

504. Drum lam ford .

0-04

555. an Dubh (Lochy) . . O'Ol

505. Fyntalloch

0'04

556. Rainbow .... O'Ol

506. Kilchoan (Upper) .

0-04

557. Dubh (Ness) . . . O'Ol

507. Ree

0-04

558. Choire na Cloich . . O'Ol

508. Muck ....

0-04

559. nan Losganan . . . O'Ol

509. Geal ....

0-04

560. St Margaret's . . . O'Ol

510. Browster ....

0-04

561. Dim (Portsonachan) . 0'003

511. Bran . . . . 0'04

562. Allt na Mult . . . 0-003

STATISTICAL TABLES

xxix

TABLE III

FRESH-WATER LOCHS OF SCOTLAND (SOUNDED BY THE LAKE SURVEY)

ARRANGED ACCORDING TO MAXIMUM DEPTH

Loch.

Max.
Depth.
Feet.

Loch.

Max.
Depth.
Feet.

1. Morar ....

1017

54. Scamadale

145

2. Ness ....

754

55. Fionn (Gruinard)

144

3. Lomond ....

623

56. Ba(Mull)

144

4. Lochv ....

531

57. a' Bhaid-Luachraich

143

5. Ericht ....

512

58. Eck

139

6. Tay

508

59. Ossian .

132

7. Katrine ....

495

60. Lungard ...

129

8. Rannoch ....

440

61. Tummel .

128

9. Treig ....

436

62. Laidon ,

128

10. Sbiel ....

420

63. Veyatie ....

126

11. Maree ....

367

64. Clunie (Ness) .

123

12. Glass ....

365

65. Cam ....

122 i

13. Arkaig ....

359

66. na h-Oidhche .

121

14. More (Laxford).

316

67. a' Bhaid Daraich

121

15. Awe (Etive)

307

68. Gainmheich (South) .

120

16. Earn ....

287

69. Eilt

119

17. Assynt ....

282

70. Achilty ....

119

18. Fannich . * .

282

71. Tralaig ....

117

19. Quoich .

281

72. Arienas ....

116

20. Mode ....

270

73. Nell ....

115

21. Monar ....

260

74. Dubh-M6r

114

22. Muick ....

256

75. na h-Airidh Sleibhe .

113

23. Fada(Ewe) .

248

76. Garry (Tay) .

113

24. Atfric ....

221

77. Bunacharan

113

25. Suainaval

219

78. Vennachar

111

26. na Sheallag

217

79. nan Lann

109

27. Laoghal ....

217

80. Dhugaill (Torridon i .

108

28. Skinaskink

216

81. Stack ....

108

29. Garry (Ness) .
30. Damh (Torridon)

213
206

82. Naver ....
83. Ard

108
107

31. Dim na Seilcheig

205

84. Garve ....

105

32. Frisa ....

205

85. an Duin (Spey)

102

33. Mullardoch

197

86. Lyon ....

100

34. Avich ....
35. Hope ....

188
187

87. an Laghair
88. Eilde Mor

100
100

36. Bad a; Ghaill .

180

89. Doon ....

100

37. Dhughaill (Carron) .

179

90. lush ....

100

38. Beannachan

176

91. Voil

98

39 Laggan ....

174

92. Langavat (Lewis) .

98

40. a' Chroisg

168

93. an t-Seilich

98

41. Beinn a' Mheadhoin .

167

94. Achray ....

97

42. Luichart ....

164

95. Drunkie ....

97

43. Shin

162

96. Daimh (Tay) .

95

44. Beoraid ....

159

97. Beuisval ....

95

45. an Dithreibh .

157

98. Raonasgail

95

46. Lurgain ....

156

99. Dungeon ....

94

47. Oich ....

154

100. a' Mhnilinn

94

48. Dubh (Ailort) .

153

101. Garbhaig.

93

49. St Mary's

153

102. na Creige Duibhe

93

50. Owskeich ....

153

103. Clair(Ewe)

93

51. Coir' an Fhearna

151

104. Kernsarv ....

93

52. Obisary ....

151

105. Nant . . .

92

53. Lubnaig ....

146

106. a' Bhealaich (Gairloch) .

92

XXX

THE FRESH-WATER LOCHS OF SCOTLAND

TABLE III— continued

Loch.

Max.

Depth.
Feet.

Loch.

Max.

Depth.
Feet.

107. Gorm Loch Mor

91

166. an Eilein (Spev)

66

108. Seil ....

91

167. Brora .

66

109. Mhor ....

91

168. Doine ....

65

110. Fionn (Kirkaig)

90

169. lubhair ....

65

111. Grunavat.

90

170. Benachally

64

112. Tarff ....

89

171. Bad an Sgalaig .

64

113. Dubh (Gruinard)

88

172. a' Ghriania

64

114. na Leitreach

88

173. Loch on Eilean Subhainn .

64

115. Baile a' Ghobhainn .

88

174. na Meide ....

63

116. Tollie ....

86

175. Ken ....

62

117. Builg ....

86

176. Freuchie ....

62

118. Calder ....

85

177. an Tachdaidh .

62

119. na Cuaich

85

178. Raoinavat

61

120. Merkland

85

179. Dibadale ....

61

121. a' Ghlinne Dorcha ,

85

180. Tingwall ....

60

122. Oeagach ....

84

181. Hunder ....

60

123. Tulla ....

84

182. a' Choire ....

60

124. Calavie ....

84

183. na Moine Buige

60

125. Leven ....

83

184. Kilcheran

60

126. Scaslavat ....

82

185. Allt na h-Airbhe

60

127. na h-Earba (West) .

81

186. Gainmheich (North)

59

128. Lodh ....

81

187. nan Druimnean

59

129. a' Chlachain (Nairn)

80

188. Lowes (Tweed)

58

130. a' Bhealaich (Naver)

80

189. Lochrutton

58

131. Turret ....

79

190. Ederline ....

58

132. an Leoid ....

79

191. na Beithe

58

133. Fender ....

78

192. Fiart ....

58

134. Menteith ....

77

193. Drutnellie

58

135. Edgelaw ....

77

194. Pattack ....

58

136. Chon (Forth) .

75

195. Aithness ....

57

137. Knockie ....

75

196. Ashie ....

57

138. Eion Mhic Alastair .

74

197. Hoglinns ....

57

139. Phitiulais

74

198. an Losgainn Mor

57

140. Girlsta ....

74

199. Clousta ....

57

141. Caravat ....

74

200. Fleet ....

56

142. a' Rhraoin

73

201. nan Deaspoirt .

56

143. Talla ....

73

202. Sealbhag ....

56

144. Clings ....

73

203. Fada (Gruinard)

56

145. Sgamhain

72

204. Skiach

55

146. Kennard ....

72 •

205. Trool ....

55

147. Fiodhaig ....

71

206. an t-Slagain .

55

148. Crocach ....

71

207. Liath ....

55

149. 'nam Breac

71

208. Kosebery ....

55

150., Kilchoan (Upper)
151. Leitir Easaich .

70
70

209. Mill ....
210. an Drain c

55
55

152. Alvie ....

70

211. Gaol na Doire .

55

153. nam Breac Dearga .

70

212. Dilate ....

55

154. Achall ....

70

213. Lochaber ....

55

155. Lintrathen

70

214. Crogavat ....

55

156. Derculich

70

215. Gladhouse

55

157. Clunie(Tay) .

69

216. Eela ....

55

158. a' Mhiotailt

69

217. Lundie (Garry)

54

159. na h-Earba (East) .

69

218. Harelaw ....

54

160. Ordie ....

69

219. Crombie Den .

53

161. Grennoch

68

220. Lowes (Tay) .

53

162. Dubh (Gairloch)

68

221. a' Phearsain .

53

163. Arklet ....

67

222. Gown (South) .

52

164. Killin ....

67

223. an Daimh (Shin)

52

165. na.Beinne Baine

67

224. Braigh Horrisdale .

51

STATISTICAL TABLES

TABLE III — continued

XXXI

Max.

Max.

Loch.

Depth.

Loch.

Depth.

Feet.

Feet.

225. Kemp ....

51

284. Kindar ....

41

226. Leum a' Chlamhain .

51

285. Gamhna ...

41

227. an Staca ....
228. Lochindorb

51
51

286. Spiggie ....
287. White of Myrton .

41
40

229. Mov ....

50

288. Craggie ....

40

230. Bran ....

50

289. Finlas ....

40

231. Black (Ryan) .

50

290. an Dubh (Lochy)

40

232. Inbhir ....

50

291. Stacsavat

40

233. Arthur ....

50

292. Urigill ....

40

234. na Craobhaig .

50

293. Monzievaird

39

235. Scadavay (East)

50

294. na Lairige

39

236. nan Eun (Tay).

50

295. Fadagoa ....

39

237. Giorra ....

49

296. an Tuirc ....

39

238. Migdale ....

49

297. nan Aiiscot

39

239. Woodhall

49

298. Howie ....

39

, 240. Ghuilbhm

49

299. Burntisland

39

241. Morlich ....

49

300. Tearnait ....

39

242. Coulin (Ewe) .

49

301. na Claise Fearna

38

243. Gleann a' Bhearraidh

48

302. White (Ryan) .

38

244. Doire nam Mart

48

303. Fad

38

245. an Droighinn .

48

304. Beannach (Inver) .

38

246. Fingask ....

48

305. Holl ....

38

247. Poulary ....

47

306. Kinghorn

38

248. Bodavat .

46

307. a' Bharpa

37

249. Hoil ....

46

308. Ghinragarstidh

37

250. Birka ....

45

309. Scadavay (West)

37

251. Fada (X. Uist)

45

310. Dee . " .

36

252. Meiklie ....

45

311. Allt an Fhearna.

36

253. Kilchoan (Lower)

45

312. Buidhe (Fleet) .

36

254. Ree

44

313. Black (Etive) (East).

36

255. a' Bhealaich (Alsh) .

44

314. Skeen (Annan)

36

256. Mama ....

44

315. a' Bhuird

36

257. Expansions of Rivei Dee .

44

316. Skae ....

35

258. Craiglush

44

317. Trealaval.

35

259. an Tomain

44

318. an Duin (X. Uist) .

35

260. Skebacleit

44

319. na Beiste ....

35

261. Uanagan ....

43

320. Loyne (East) .

35

262. na Sreiuge

43

321. Ussie ....

35

263. a' Chuilinn (Conon) .

43

322. anXostarie

35

264. na h-Eaglais .

43

323. Langavat (Benbecula)

34

i 265. Doehard ....

42

324. Gryfe

34

266. Ruthven ....

42

325. an Eilein (Gairloch) .

34

267. Urr

42

326. Ochiltree ....

34

268. Skealtar ....

42

327. Auchenreoch .

34

269. Thorn ....

42

328. n a Deighe fo Dheas .

34

270. Baddanloch

42

329. ic Colla ....

34

271. an Laig Aird .

42

330. Coire nam Meann

33

272. Soulseat ....

42

331. Sron Smeur

33

273. Bhac ....

42

332. Eileach Mhic'illeRiabhaich

33

274. na Ceithir Eileanu .

42

333. Skerrow ....

33

275. Loug ....

42

334. Whinyeon

33

276. Breaclaich

41

335. Urrahag ....

33

277. Harperleas

41

336. Roer ....

32

278. Portmore.

41

337. White (Tay) .

32

279. Bhradain ....

41

338. a' Chlair (Helmsdale)

32

280. Heouravay

41

339. Deoravat ....

32

281. Dubh (Forth) .

41

340. Ceo-Glas ....

32

282. Hennidale

41

341. Hosta ....

31

283. Hostigates

41

342. Sloy ....

31

xxxii THE FRESH- WATER LOCHS OF SCOTLAND

TABLE III — continued

Loch.

Max.
Depth.

Feet.

Loch.

Max.
Depth.
Feet.

343. Druim Suardalain .

31

402. Bad a' Chrotha

23

344. nan Eun (N. Uist) .

31

403. a' Buaille ....

23

345. Morsgail ....

31

404. Muck ....

23

346. Balgavies.

31

405. Airidh na Ceardaich

22

347. Burga ....

30

406. an Stromore ... 22

348. Chaluim ....

30

407. Monikie (North)

22

349. an Gead ....

30

408. Duartmore

22

350. Ba (Tay) ....

30

409. nam Faoileag .

22

351. Callater ....

30

410. Black (Etive) (West)

22

352. Harperrig

30

411. Cro Criosdaig .

21

353. Funds ....

30

412. nan Eun (Ness)

21

354. Kilbirnie ....

30

413. Borralan ....

21

355. Forfar ....

29

414. Cliff ....

21

356. Harrow ....

29

415. Gartmorn ....

21

357. Martnaham

29

416. a' Chaoruinn .

20

358. Allan ....

29

417. Leodsay ....

20

359. an Duna .

29

418. na Moracha

20

360. Snarravoe

29

419. Ohoire na Cloich

20

361. na Salach Uidhre .

29

420. na Garbh -Abhuinn .

20

362. Beag ....

29

421. a'Bhaillidh .

20

363. Cults ....

28

422. Muckle Water .

20

364. a' Bhainne

28

423. Airidh na Lie .

19

365. na h-Achlaise .

28

424. Pitlyal ....

19

366. Eigheach ....

28

425. Oban a' Chlachain .

19

367. nan Cuinne

28

426. Loyne (West) .

19

368. Olubbi Shuns .

28

427. Essan ....

18

369. a' Ghobhainn .

28

428. Dubh (Ness) .

18

370. Black (Etive) (Mid) .

27

429. an Lagnin

18

371. Valtos ....

27

430. nan Geireann (Mill) . . 18

372. nan Geireann .

27

431. an t-Seasgain .

18

373. Beannach (Gruinard)

27

432. Castle (Annan)

18

374. a' Chonnachair

27

433. Carlingwark

17

375. nan Rath

27

434. Peppermill

17

376. Anna ....

27

435. Gown (North) .

17

377. a' Vullan ....

27

436. Stenness ....

17

378. Linlithgow

27

437. Auchenchapel .

17

379. Muckle Lunga .

27

438. Crann ....

17

380. an Ruathair .

26

439. Threipmuir

17

381. Aslaich ....

26

440. Vatandip ....

17

382. Rainbow ....

26

441. Swannay ....

16

383. Monikie (South) . .

26

442. Rae ....

16

384. Drumlamford .

26

443. Fitty ....

16

385. na Gealaich

25

444. Droma ....

16

386. na Coinnich

25

445. Tutach ....

16

387. Lunn da-Bhra .

25

446. Kinellan ....

16

388. nan Garbh Chlachain

25

447. an lasgaich

16

389. Vaara ....

25

448. Fithie ....

16

390. Veiragvat

25

449. Lochenbreck

15

391. Kirk .

25

450. Milton ....

15

392. Huna ....
393. Crunachan

25
25

451. Fyntalloch
452. Kirriereoch

15

15

394. Butterstone

25

453. Moraig ....

14

395. Lundie (Clunie)

25

454, Whitefield

14

396. Strandavat

25

455. Sguod ....

14

397. Ailsh ....

24

456. Ciiil na Sithe .

14

398. an Tairbeirt Stuadhaich .

24

457. Harray ....

14

399. Taruinn an Eithir .

23

458. Maberry ....

14

400. Rescobie ....

23

459. na Stainge

14

401. Geal ....

23

460. Magillie ....

14

STATISTICAL TABLES

TABLE III — continued

XXX111

Loch.

Max.
Depth.
Feet.

Loch.

Max.
Depth
Feet.

461. na Creige Leithe

14

512. Hempriggs

8

462. na Crai^e

13

513. Dallas ....

8

463. HightaeMill .

13

514. na h-Ealaidh .

8

464. Asta ....

13

515. na Moine ....

8

465. North-house

13

516. Flugnrth ....

8

466. Mochrum . . . .

13

517. Black (Tay) .

7

467. Strom ....

13

518. More (Thurso) .

7

468. Watten ....

12

519. Dliomhnuill Bhig .

7

469. Truid air Sgithiche .

12

520. Cornish ....

7

470. Olavat ....

12

521. Eye

7

471. Mhic' ille Riabhaich .

12

522. Hundland

7

472. Syre ....

12

523. Shurrery ....

7

473. Derelach ....

12

524. nan Losganan .

7

474. Kinord ....

12

525. Araich-Lin

7

475. Monk Myre

12

526. St John's

7

476. Scoly ....

12

527. Sandy ....

7

477. Drummond

12

528. Awe (Inver) .

7

478. Castle (Bladenoch) .

11

529. na Garbh-Abhuinn Ard .

7

479. a' Chlachain (Lewis) .

11

530. Tankerness

7

480. Brouster ....

11

531. Lure ....

7

481. Dochart ....

11

532. na Bi

6

482. Aboyne ....

11

533. Moor Dam

6

483. Denial ....

10

534. Kilconquhar

6

484. Uaine .

10

535. Grass ....

6

485. Oban nam Fiadh

10

536. Skene (Dee) .

6

486. Dhu (Portsonachan) .

10

537. Spynie ....

6

487. Eldrig ....

10

538. Lochnaw ....

6

488. Lindores ....

10

539. Kirbister ....

6

489. Peerie ....

10

540. Braidale ....

6

490. Dubh(Etive) .

10

541. Brow ....

6

491. Burralaiid

10

542. Tilt

5

492. Duddingston .

10

543. Blairs ....

5

493. Clickhimin

10

544. Scarmclate

5

494. Tormasad.

10

545. Castle Semple .

5

495. Lochinvar ... 10

546. Heilen ....

5

496. Collaster . . . . ' 10

547. Bosquoy ....

5

497. Broom . . . . 9

548. nan Gabhar

5

498. Boardhouse

9

549. St Margaret's .

5

499. na Doire Daraich

9

550. Kirk Dam

5

500. Davan ....

9

551. Bogton ....

4

501. Littlester .... 9

552. Skaill ....

4

502. a' Chladaich . . 9

553. Sand ....

4

503. Con (Tay) ... 9

554. Brough ....

4

504. Cuil Airidh a' Flod . . 9

555. Sior

4

505. Laide ... 9

556. Stormont.

3

506. Gelly . . . . . 9

557. AlltnaMult .

3

507. Achanalt . . . . ! 9

558. S*biston ....

3

508. Shechernich . . . 8

559. Wester ....

3

509. More Barvas . . .8

560. Ishister ....

3

510. Maol a' Choire ... 8

561. Buidhe(Tay) .

3

511. Bradan .... 8

562. Setter ....

2

xxxiv THE FRESH-WATER LOCHS OF SCOTLAND

TABLE IV
FRESH-WATER LOCHS OF SCOTLAND (SOUNDED BY THE LAKE SURVEY)

ARRANGED ACCORDING TO MEAN DEPTH

Loch.

Mean
Depth.
Feet.

Loch.

Mean
Depth.
Feet.

1. Ness ....

433-02

53. a' Bhaid Daraich .

55-60

2. Morar ....

284-00

54. na h-Oidhche .

53-95

3. Lochy ....

228-95

55. Achilty ....

51-78

4. Treig

207-37

56. Shin ....

51-04

5. Katrine ....

199-19

57. Dubh-M6r

50-93

6. Tay

199-08

58. Eck

50-16

7. Ericht ....

189-21

59. Bunacharan . . .

50-11

8. Rannoch ....

167-46

60. Clunie (Ness) .

49-98

9. Glass ....

159-07

61. Garry (Tay) .

49-91

10. Arkaig ....

152-71

62. Tummel ....

48-03

11. Earn ....

137-83

63. Ba(Mull)

47-42

12. Shiel ....

132-73

64. Eilde Mor

47-01

13. More (Laxford)

125-83

65. Owskeich ....

46-90

14. Maree ....

125-30

66. Lyon ....

44-87

15. Morie ....

125-20

67. na h-Aiddh Sleibhe .

44-43

16. Lomond ....

121'29

68 Ard

-13-86

17. Muick !

116-30

69. Garve ....

43-60

18. Fannich ....

108-76

70. Lubnaig ....

42-77

19. Suainaval.

108-60

71. Ossian .

42-75

20. Awe (Etive) .

104-95

72. na Cuaieh

42-48

21. Quoich ....

104-60

73. Vennachar

42-41

22. na Sheallag . . ' .

103-47

74. Dubh (Grninard)

42 -33

23. Fada(Ewe)

102-20

75. Clair (Ewe)

42-10

24. Assynt .

101-10

76. Gainmheich (South) .

41-80

25. Avich ....

98-42

77. Oich ....

41-78

26. Monar ....

98-33

78. an t-Seilich

41-30

27. Affric ....
28. Dun na Seilcheig

93-64

84-00

79. Tralaig ....
80. Veyatie ....

41-03
41-00

29. Garry (Ness) .

78-00

81. Voil

40-94

30. Mullardoch

77-52

82. na Leitreach

40-29

31. Frisa ....

76-40

83. Eion Mhic Alastair .

39-73

32. a' Chroisg . ...

73-78

84. Daimh (Tay) .

39-12

33. St Mary's

72-93

85. Naver ....

39-06

34. Beoraid .

72-34

86. Baile a' Ghobhainn .

3877

35. Beannachan

70-42

87. Dhugaill (Torridon) .

38-27

36. Scamadale

69 58

S8'17

37. Laggan ....

67-68

89. Tulla ....

38-08

38. Luichart ....

66-84

90. Calavie ....

37-91

39. Dhughaill (Carron) .
40. an Dithreibh .

66-65
65-93

91. Cam ....
92. Insh ....

37-70
37-31

41. Beinn a' Mheadhoin .

65-36

93. an Laghair

37-23

42. Laoghal ....

65-21

94. Eilt

37-12

43. Lungard ....

63-68

95. nan Lann

37-03

44. Dubh(Ailort) .

62-70

96. Nell

36-80

45. Bad a' Ghaill .

61-90

97. Seil

36-73

46. Hope ....

61-47

98. a' Bhraom

36-60

47. Lurgain ....

60-90

99. Lowes (Tweed) .

36-55

48. Skinaskink

60-40

100. Drunkie ....

36-05

49. Damn (Tortidon)

58-91

101. Achray ....

36-01

50. Coir' an Fhearna

58-79

102. Stack ....

35-91

51. Fionn (Gruinard)

57-79

103. an Leoid ....

35-75

52. Arienas ....

56-60

104. na h-Earba(West) .

35-62

1

STATISTICAL TABLES

TABLE IV— continued

xxxv

Loch.

Mean
Depth.
Feet.

Loch.

Mean
Depth.
Feet.

105. Garbhaig ....

35-41

163. Benachally . . .25*06

106. Laiclon ....

35-19

164. lubhair . . . 24 '96

107. Talla ....

3470

165. Langavat (Lewis) . . 2479

108. Benisval ....

34-63

166. Derculich . . .2472

109. Scaslavat ....

34-65

167. Crogavat . . . .24*66

110. a'Mhuilinn

34-15

168. na Moine Buige . . 24 '62

111. a' Bhaid-Luachraich

34-02

169. Gainmheich (North) . . 24 '50

112. Creagach ....

33-17

170. nam Breac Dearga . . 24 '43

113. Doine ....

33-13

171. Knockie . . . 24 '40

114. Tollie ....

33-13

172. Nant .... 24'31

115. a' Bhealaioh (Gairloch) .

3274

173. Gorm Loch Mor . . 24-30

116. na Creige Duibhe . . j 32 '49

174. Arklet .... 24'19

117. Raonasgail . . . 32 '37

175. Killin . . . .24-15

118. Keuuard ....

32-27

176. Mhor .... 24*11

119. Turret ....

3179

177. Tarff .... 23 '89

120. Fender ....

31-77

178. Dilate .... 23-50

121. Dubh (Gairloch)

31-74

179. Lintrathen . . . 23 '42

1-22. Girlsta ....

31-41

180. Black (Ryan) . . . 23 '37

123. a' Bhealaich (Naver)

31-20

181. Ederline ... . 23*15

124. na h-Earba (East) .

31-11

182. Phitiulais. . . . 23 '15

125. Edgelaw ....

31-10

183. Fiart . . . . ; 23 '13

126. an Duin (Spey)

30-38

184. Gaol na Doire . . . 23 '04

127. a' Mhiotailt '.

30-30

185. nah-Eaglais . . . 22 "84

! 128. Allt na h-Airbhe

30-17

186. Fiugask ....

22 83

129. Merkland

30-14

187. Freuchie .... 22 '83

130. a' Chlachain (Nairn)

29-84

188. Harelaw .... 22 '83

131. Loch on Eilean Subhainn .

29-70

189. Brora .... 22'68

132. Kilchoan (Upper)

29-54

190. Dungeon .... 22'64

133. Chon (Forth) .

29-38

191. Liath .... 22'36

134. Loch ....

29-22

192. Meiklie ....

22*10

135. Drumellie

29-18

193. Fleet ....

21-81

136. Chmie(Tay) . . . 29'12

194. Giorra ....

2170

137. Grunavat . . .28*36

195. nan Eun (Tay) .

21-64

138. na Beinne Baine . . 28 '33

196. Doire nam Mart

21*33

139. a' Ghriama . . . 28 '03

197. Ashie ....

21*26

140. nam Breac . . . 27 '94

198. Migdale ....

21-18

141. Achall ....

27-83

199. Kilcheran

21*11

142. Dibadale ....

2777

200. Ken

21-00

143. Builg .... 27-75

201. Calder ....

20-87

144. na Beithe . . . 27 '72

202. nan Deaspoirt .

20-82

145. a' Ghlinne Dorcha . . 27 '65

203. Grennoch ....

20-82

146. a' Choire ....

27-55

204. Dubh (Forth) .

2070

147. an Daimh (Shin)

27-17

205. Sealbhag ....

20-66

148. Alvie . . . . 27'02

206. na Meide ....

20*61

149. Sgamhain . . .26*77

207. Lochaber ....

20-57

150. Doon .... 26*71

208. Raoinavat

20-56

151. Clings . . . 26 '55

209. Fionn ....

20-40

152. Ordie ....

26-32

210. Lowes (Tay) .

20-40

153. Kemp . . . . j 26 '23

211. Kilchoan (Lower)

20-30

154. Hoglinns . . . . 26'09

212. Leitir Easaich .

19-90

155. an Drainc . . . 25 '86

213. Menteith. . . . 1977

156. Fiodhaig . . . .2579

214. Woodhall . . . 19 '67

157. Arthur .... 25 -77

215. Leum a' Chlarnhain . . 19'54

158. Obisary . . . .2570

216. a' Phearsain . . . ; 19 '44

159. an Eilein (Spey) . . 25 '47

217. Mov . . . .19-31

160. Mill .... 25-33

218. Thorn . . . 19 '25

161. Bad an Sgalaig . . 25'26

219. Hoil .... 19-09

162. Rosebery .... 25 '20

220. Tingwall ....

18-88

xxxvi THE FRESH- WATER LOCHS OF SCOTLAND

TABLE IV — continued

Loch.

Mean
Depth.
Feet.

Loch.

Mean
Depth.
Feet.

221. Aithness ....

18-84

279. Eileach Mhic' ille Riabhaich

14-13

222. an Losgaiun Mor

18-65

280. Breaclaich

14-09

223. Trool ....

18-39

281. White (Ryan) .

14-09

224. Coulin (Ewe) .

18-29

282. Pattack ....

14-07

225. Braigh Horrisdale .

18-10

283. Expansions of River Dee .

13-90

226. Skiach ....

18-09

284. na Ceithir Eileana .

13-81

227. Hunder ....

18-08

285. White of Myrton

13-70

228. Harperleas

17-88

286. a' Chlalr (Helmsdale)

13-65

229. an Tachdaidh .

17-88

287. Monikie (South)

13-47

230. Skeen (Annan) .

17-87

288. Vaara ....

13-44

231. Crornbie Den .

17-64

289. Black (Etive) (East) .

13-39

232. na Sreinge

17-53

290. an Ruathair

13-34

233. Stacsavat.

17-43

291. Ghuilbinn

13-32

234. Gryfe ....

17-35

292. i) a Claise Fearna

13-23

235. Baddanloch

17-33

293. Beannach (Inver)

13-20

236. Fada (Gruinard)

17-15

294. an Diina ....

13-12

237. Fad

17-13

295. Udgill

13-10

238. Holl ....

17-04

296. Lochrutton

13-03

239. Crocach ....

16-80

297. White (Tay) .

12-95

240. Uanagan ....

16-80

298. Gleann a' Bhearraidh

12-79

241. nan Auscot

16-79

299. Anna ....

12-74

242. Portmore ....

16-79

300. Burga . . - .

12-65

243. na Craobhaig .

16-63

301. Bran

12-63

244. Eela

16-59

302. Skerrow ....

12-63

245. Caravat ....

16-57

303. Bodavat ....

12-61

246. a' Bhealaich (Alsh) .

16-53

304 a' Ghobhainn .

12-59

247. Bhac ....

16-50

305. Monikie (North)

12-58

248. an Toraain

16-47

306. Snarravoe

12-55

249. Gladhouse

16-46

307. Hermidale

12-49

'. 250. an t-Slagain

16-42

308. Hosta ....

12-47

251. Lundie (Garry)

16-28

309. a' Bharpa ....

12-43

252. Hostigates

16-26

310. Lochindorb

12-42

253. Tearnait ....

16-16

311. nan Cuinne

12-38

254. Craiglusli.

16'13

312. Morsgail ....

12-33

255. Skealtar ....

15-90

313. a' Vullan ....

12-27

256. Gown (South) .

15-88

314. Whinyeon

12-22

257. Howie ....

15-69

315. Urr .'

12-06

258. nan Druimnean

15-61

316. Callater ....

11-99

259. an Staca .

15-52

317. Burntisland

11-85

260. an Dubh (Lochy) .

15-50

318. Dochard ....

11-84

261. Kinghorn.

15-33

319. Birka ....

11-81

262. Craggie ....

15-31

320. Beag ....

11-80

263. Clousta ....

15-27

321. Buidhe (Fleet) .

11-72

264. Skebacleit

15-21

322. Fadagoa ....

11-70

265. Soulseat ....

15-19

323. Auchenreoch .

11-69

266. an Laig Aird .

15-12

324. Harrow ....

11-61

267. Ree .....

14-96

325. Coire nam Meann

11-60

268. Leven ....

14-87

326. Deoravat ....

11-60

269. Bhradain ....

14-83

327. Spiggie ....

11-59

270. an Droighinn .

14-78

328. Urrahag ....

11-49

271. Monzievaird

14-70

329. Forfar ....

11-43

272. Morlich ....

14-62

330. an Gead ....

11-29

273. an Eilein (Gairloch) .

14-39

331. Butterstone

11-29

274. Rainbow ....

14-33

332. Black (Etive) (Mid) .

11-27

275. Allt an Fhearna

14-31

333. Ruthven ....

11-27

276. Mama ....

14-29

334. Muckle Water .

11-08

277. Dee

14-25

335. na Lairige

10-97

278. Kindar ....

14-22

336. Harperrig

10-96

STATISTICAL TABLES

TABLE IV — continued

XXXVll

Loch.

Mean
Depth.
Feet.

Loch.

Mean
Depth.
Feet.

337. an Nostarie

10-95

395. Peppernrill

8-60

338. Aslaich ....

10-91

396. Castle (Annan)

8-58

339. Drumlamford .

10-82

397. nan Geireann .

8-47

340. ic Colla ....

10-77

398. Limn da-Bhra .

8-44

341. Gartmorn

1075

399. Watten ....

8-42

342. Cliff

10-65

400. Pitlyal ....

8-32

343. an Tuirc ....

10-60

401. Ailsh ....

8-30

344. na Beiste ....

10-56

402. Auchenchapel .

8-26

345. na Deighe fo Dheas .

10-54

403. nan Rath ....

8-23

346. an Tairbeirt Stuadhaich .

10-50

404. Huna ....

8-22

347. Stenness ....

10-43

405. Langavat (Benbecula)

8-12

348. a'Bhuird. . . . 1 10 '42

406. Sloy ....

8-12

349. Allan . . . . 10 '40

407. Ba (Tav) ....

8-10

350. Geal . . . .10'38

408. Whitefield

8-01

351. Loyne (East) . . . 10 '32

409. Ussie ....

7-98

352. Sron Smeur . . . 10 '31

410.' Chaluim ....

7-92

353. Druim Suardalain . . 10 '30

411. Threipmuir

7-90

354. Fada(X. Uist) . . . 10 -25

412. Inbhir ....

7-85

355. a' Chuilinn (Conon) . . 10'22

413. nan Eun (N. Uist) .

7-84

356. Funds . . . . 10-20

414. Lundie (Clunie)

7-80

357. Roer . . . .10-16

415. Crunachan

7-79

358. Ceo-Glas . . . .10-14

416. Oehiltree ....

7'68

359. Rescobie '

9-99

417. Lochenbreck

7-61

360. Kirk ....

9-96

418. a' Bhaillidh .

7-60

361. na Gealaich

9-94

419. an Lagain

7-57

362. Long ....

9-92

420. Linlithgow

7-55

363. nan Eun (Ness)

9-90

421. Fyntalloch

7-48

364. Poulary ....

9-90

422. i) a Craige ....

7-42

365. Vatandip ....

9-85

423. Cuil na Sithe .

7-42

366. Balgavies ....

9-76

424. Derclach ....

7-42

367. Oban a' Chlachaiu .

9-75

425. Fithie ....

7-42

368. Kilbirnie ....

972

426. Fitty ....

7-40

369. a' Bhainne

9-69

427. Valtos ....

7-40

370. Finlas ....

9-69

428. Leodsay ....

7-38

371. Martnaham

9-61

429. Heouravay

7-37

372. Borralan ....

9-60

430. Black (Etive) (West)

7-34

373. na h-Achlaise .

9-58

431. Maberry ....

7-32

374. Gamhna ....

9-56

432. HightaeMill .

7-31

375. Skae ....

9-52

433. nan Garbh Chlachain

7-28

376. Choire na Cloich

9-44

434. Kinellan ....

7-14

377. a' Chaoruinn .

9-37

435. Muck ....

7-12

378. na Moracha

9-26

436. Dubh (Ness) .

7-00

379. Swannay ....

9-22

437. na Creige Leithe

7-00

380. Trealaval ....

9-22

438. Strom ....

7-00

381. Airidli na Lie .

9'21

439. Kirriereoch

6-98

382. Cults ....

9-16

440. Sguod ....

6-91

383. Scadavay (West)

9'16

441. Muckle Lunga .

6-88

384. Ghiuragarstidh

9-08

442. Gown (North) .

6-87

385. Han-ay ....

9-02

443. Carlingwark .

6-86

386. an Stromore

9-01

444. a' Buaille ....

6-82

387. a' Chonnachair . . . I 8 '88

445. Essan ....

6-82

388. Clubbi Shuns .

8-85

446. Crann ....

679

389. Cro Criosdaig .

8-80

447. Mochrum ....

6-75

390. nam Faoileag .

8-69

448. Milton ....

6-67

391. Veiragvat

8-68

449. North-house .

6-60

392. Scadavay (East)

8-67

450. Rae

6-59

393. naCoinnich .

8-62

451. Castle (Bladenoch) .

6-56

394. Strandavat

8-61

452. na Salach Uidhre

6-54

xxxviii THE FRESH- WATER LOCHS OF SCOTLAND

TABLE IV — continued

Loch.

Mean
Depth.
Feet.

Loch.

Mean
Depth.
Feet.

453. Beannach (Gruinard)

6-45

508. Achanalt ....

4-50

454. Lochinvar

6-41

509. a'Chladaich .

4-50

455. nan Geireann (Mill) .

6'37

510. Cuil Airidh a' Flod .

4'50

456. Tarruin an Eithir

6-37

511. St John's

4-50

457. Peerie ....

6-34

512. Bruadale ....

4'46

458. an Duin (N. Uist) .

6-27

513. Araich-Lin

4-45

459. Droma ....

6-27

514. Bradan ....

4-40

460. Eigheach ....

6-09

515. Shurrery ....

4-37

461. Bad a' Chrotha

6-08

516. Tankerness

4-35

462. Boardhouse

6-06

517. More Barvas

4-33

463. Aboyne ....

6-03

518. Hundland

4-32

464. Loyne(West) .

5-93

519. Lochnaw ....

4-32

465. Duartmore

5-90

520. Oban nam Fiadh

4-23

466. Collaster ....

5-88

521. Olavat ....

4-20

467. Airidh na Ceardaicli .

5-86

522. More (Thurso) .

4-18

468. Truid air Sgithiche .

5-83

523. Kirbister ....

4-15

469. an t-Seasgain .

572

524. Eye

4-06

470. Scoly ....

5*72

525. Shechernich

4-01

471. Eldrig ....

5-70

526. Da van ....

3-98

472. Clickhimin

5'60

527. Dhomhnuill Bhig .

3-90

473. Torniasad.

5-60

528. Lure ....

3-90

474. Brouster ....

5-57

529. Kilconquhar

3-90

475. an lasgaich

5-55

530. Cornish ....

3'80

476. Moraig ....

5-54

531. na Doire Daraich

3-60

477. a' Chlachain (Lewis) .

5-52

532. Dallas ....

3-50

478. Syre ....

5-48

533. nan Losganan .

3'50

479. Magillie ....

5-37

534. Uaine ....

3-50

480. Dornal ....

5-36

535. Con (Tay)

3-47

481. Mhic' ille Riabhaich.

5-35

536. na Bi . .' .

3-30

482. Flugarth ....

5-23

537. Moor Dam

3-27

483. Hempiiggs

5-22

538. na Garbh-Abhuinn Ard .

3-02

484. Laide ....

5-16

539. Grass ....

2-99

485. Duddingston

5-14

540. Dubh (Etive) .

2-76

486. Asta ....

5-11

541. Spynie ....

2-71

487. Maol a' Choire .

5-10

542. Blairs ....

2-55

488. na Stainge

5-10

543. Brow ....

2-50

489. Drummond

5-09

544. Bosquoy ....

2-50

490. Monk Myre

5-08

545. Castle Semple .

2-50

491. Lindores ....

5-06

546. Heileri ....

2-50

492. Gelly ....

5-03

547. nan Gabhar

2 '50

493. Kinord ....

5-03

548. St Margaret's .

2-50

494. Dochart ....

r>-02

549. Scarmclate

2-50

495. Broom ....

5-02

550. Tilt ....

2-50

496. Dhu (Portsonachan) .

5-00

551. Bogton ....

2-00

497. Kirk Dam

5-00

552. Brough ....

2-00

498. Tutach .

4-88

553. Sand ....

2-00

499. Awe (Inver)

4-80

554. Sior

2-00

500. Sandy ....

4-76

555. Skaill ....

2-00

501. Black (Tay) .

473

556. Allt na Mult .

1-50

502. Skene(Dee) .

4-69

557. Buidhe(Tay) .

1-50

503. Burraland

4-67

558. Isbister ....

1-50

504. na h-Ealaidh .

4-66

559. Sabiston ....

1-50

505. na Garbh-Abhuinn .

4-65

560. Stormont ....

1-50

506. na Moine ....

4-61

561. Wester ....

1-50

507. Littlester.

4-55

562. Setter ....

1-00

STATISTICAL TABLES

xxxix

TABLE V

FRESH-WATER LOCHS OF SCOTLAND (SOUNDED BY THE LAKE SURVEY)
ARRANGED ACCORDING TO VOLUME OF WATER

Volume

Volume

in

in

Loch.

Million

Loch.

Million

Cubic

Cubic

Feet.

Feet.

1. Ness

263,162

53. Boon ....

1,517

2. Lomond

92,805

54. Beinu a' Mheadhoin .

1,435

3. Morar ....

81,482

55. an Dithreibh .

1,366

4. Tay

56,550

56. Tummel ....

1,317

5. Awe (Etive)

43,451

57. Ossian .

1,224

6. Maree ....

38,539

58. Tulla ....

1,167

7. Ericht ....

38,027

59. Beoraid ....

1,156

8. Lochy ....

37,726

60. Ard

1,150

9. Rannoch

34,387

61. Lnbnaig

1,144

10. Shiel ....

27,986

62. Mhor ....

1,134

11. Katrine ....

27,274

63. Cam ....

1,063

12. Arkaig .

26,573

64. Veyatie .

1,062

13. Earn ....

14,421

65. Arienas ....

1,035

14. Treig ....

13,907

66. Voil .

1,000

15. Shin ....

12,380

67. Stack ....

988

16. Fannich .

10,920

68. Harray ....

951

17. Assynt .

8,731

69. Oich ....

890

18. Quoich ....

8,345

70. Garry (lay) .

846

19. Glass ....

8,265

71. Owskeich

846

20. Fionn (Gruinard)

5,667

72. Obisary

837

21. Lairgan ....

5,601

73. Dhughaill (Carron) .

823

22. More (Laxford)

4,928

74. Beannachan

819

23. Laoghal

4,628

75. na h-Oidhche .

816

24. Dun na Seileheig

4,599

76. Ken ....

792

25. Fada(Ewe) .

4,091

77. Calder ....

767

26. Hope ....

4,032

78. Garve ....

721

27. ua Sheallag

3,948

79. Stenness

716

28. Garry (Ness) .

3,794

80. Eilt ....

686

29. Frisa ....

3,603

81. Scamadale

685

30. Skinaskink

3,518

82. a' Bhraoin

669

31. Avich ....

3,327

83. Lungard

599

32. Luichart . .

3,288

84. Merkland

577 ;

33. Monar ....

3,213

85. Menteith

562

34. Morie

3,201

86. Brora ....

553

35. Suainaval

2,843

87. Nell ....

515

36. Muick ....

2,771

88. na Meide

498

37. Mullardoch

2,553

89. EildeMor

493

38. Naver

9 461

90. a' Bhaid-Luachraich

486

39. Langavat (Lewis)

2,388

91. Baddanlocb

479

40. Eck . . . . !

2,381

92. Grunavat

478

41. Leven ....

2,195

93. Lyon ....

461

42. Damh (Torridon)

2,183

94. Insh ....

454

43. Aftric ....

2,146

95. an t-Seilich

448

44. Lurgain .

2,140

96. a' Chlair (Helmsdale)

446

45. a' Chroisg . . . :

2,057

97. Talla ....

443

46. St Mary's

2,018

98. Creagach

429

47. Vennachar . . .

1,903

99. Fiodhaig

415

48. Coir' an Fhearna

1.886

100. na h-Earba ( West) .

408

49. Bad a' Ghaill .

1,768

101. Lintrathen

405

50. Laidon

1,762

102. Achall ....

401

51. Ba i Mull

1,602

103. a' Bhealaich (Gairloch)

398

52. Clunie(Ness) .

1,533

104. nan Cuinne

396

xl THE FRESH- WATER LOCHS OF SCOTLAND

TABLE V — continued

Volume

Volume

in

in

Loch.

Million

Loch.

Million

Cubic

Cubic

Feet.

Feet.

105. Dubh (Gruinard)

374

162. Lowes (Tweed)

157

106. Chon (Forth) .
107. Freuchie ....

358
347

163. Moy ....
164. Fadagoa ....

157
156

108. Bunacharan

343

165. Trealaval

156

109. Watten .

341

166. Bad an Sgalaig

151

110. Kernsary

333

167. a' Mhuilinn

150

111. Achilty .

332

168. Boardhouse

150

112. Achray ....

321

169. Black (Ryan) .

149

113. a' Ghriama

314

170. Crocach .

148

114. Ashie ....

309

171. Nant ....

148

115. Girlsta ....

308

172. lubhair .

147

116. Scadavay (West)

306

173. na Leitreach .

147

117. an Ruathair .

304

174. Hundcr . .

146

118. Leum a' Chlamhain .

298

175. Dilate ....

145

119. Lochindorb

291

176. an Eilein (Spey)

144

120. Clair(Ewe)

287

177. Woodhall .

144

121. Urigill .

285

178. Killin ....

137

122. Thorn ...

277

179. Dubh (Gairloch)

136

123. Calavie ....

276

180. Tarff ....

136

124. a' Bhaid Daraich

270

181. an Laghair

135

125. Caravat ....

270

182. an Duin (Spey)

134

126. Gladhouse

269

183. Ordie ....

133

127. Tralaig ....

267

184. Allt an Fhearna

132

128. Grennoch

263

185. Fad ....

132

129. Expansions of River Dee .

261

186. na h-Alridh Sleibhe .

131

130. Benisval ....

260

187. Skebacleit

128

131. Gainmheich (South) .

246

188. Loyne (East) .

123

132. Tollie ....

244

189. nan Geireann (Mill) .

121

133. Migdale .

242

190. Cliff ....

118

134. Swannay

242

191. Trool ....

116

135. a' Bhealaich (Naver)

238

192. anLeoid.

136. Garbhaig

228

193. nan Eun (N. Uist) . . 114

137. Turret .... 222

194. Scadavay (East) . . 112

138. Arklet ....

222

195. Spiggie . . . . HI

139. Drumellie

222

196. Allt na h-Airbhe . . HO

140. Drunkie .... 217

197. an Staca ....

110

141. na Cuaich

214

198. Fada (Gruinard)

109

142. Ba(Tay).

206

199. an Drainc

108

143. an Daimh (Shin)

205

200. Derculich . . . 108

144. Fada (N. Uist)

199

201. Harperrig ... 108

145. Doine ....

196

202. Kennard ....

108

146. Gorm Loch Mor

196

203. Pattack ....

106

147. Knockie ....

194

204. Kilbirnie

105

148. Lowes (Tay) .

194

205. nan Lann . . . 105

149. Meiklie ....

193

206. Urrahag . 105

150. Morlich ....

192

207. a' Choire . . .103

151. na h-Earba (East) .

191

208. Eela . . . . 103

152. Daimh (Tay) .

190

209. Loch . .

103

153. na Beinne Baiue

190

210. Clings .

101

154. Fionn (Kirkaig)

186

211. Strom ....

101

155. Ruthven ....

180

212. Raonasgail

94

156. Benachally

178

213. Builg ....

93

157. nam Breac

172

•214. na Craobhaig ... 93

158. Clunie (Tay) .
159. Sgamhain

170
165

215. White (Ryan) .
216. Coulin (Ewe) .

92

90

160. Alvie .... 163

217. Crogavat

90

161. Dee

157

218. Skealtar

90

STATISTICAL TABLES

TABLE V — continued

xli

Loch.

Volume
iu
Million
Cubic
Feet.

Loch.

Volume
in
Million
Cubic
Feet.

219. Ailsh ....

88

276. Muckle Water .

57

Dubh (Ailort) .

87

277. a' Bhealaich (Alsh) .

56

•221. Dungeon

87

278. Maberry

56

•222. Gryfe ....

87

279. Whinyeon

56

223. Tingwall

87

280. Urr " .

56

224. Ghuilbinn

85

281. an t-Slagain .

55

225. Giorra ....

84

282. Baile a' Ghobhainn .

55

226. Arthur ....

83

283. a' Ghobhainn .

54

227. Kindar ....

83

284. an Gead

54

228. Vaara ....

80

285. Butterstone .

53

229. Sell ....

79

286. Skeen (Annan)

53

230. a' Chlachain (Nairn)

78

287. a' Phearsain .

52

231. Lundie (Garry)

78

288. na Creige Duibhe .

52

232. Gaol na Doire .

77

289. Ochiltree.

52

233. Kemp ....

77

290. Dibadale

51

234. Skiach ....

77

291. Forfar ....

51

235. na h-Achlaise .

76

292. Hundland

51

236. Portmore

76

293. a' Chuilinn (Conon) .

50

237. Tearnait

75

294. Bodavat ....

50

238. Lochrutton

73

295. Inbhir ....

50

239. Scaslavat

73

296. nan Deaspoirt .

50

•240. an Tachdaidh-. . . 72

297. Borralan

49

241. Castle (Annan) . . 72

298. Craiglush

49

242. Clousta . 71

299. Hempriggs

49

243. Ederline .... 70

300. Straudarat

49

244. na Salach Uidhre

70

301. Huna

48

245. a' Mhiotailt .

69

302. Edgelaw

47

246. an Tomain ... 69

303. Lochaber

47

247. Rescobie ....

69

304. Martnaham .

47

248. Buidhe (Fleet)

68

305. Soulseat

47

249. Mochram ... 68

306. Truid air Sgithiche .

47

250. Skerrow . . . > 68

307. Aithness

46

Ussie .... 68

308. Fitty ....

46

252. Beannach (luver) . .67

309. Eion Mhic Alastair .

45

253. Doire nam Mart . . 67

310. Leitir Easaich .

45

254. Phitiulais ... 67

311. Milton ....

45

' 255. a' Bharpa ... 66

312. More Barvas .

45

256. Dubh-M6r ... 66

313. an Laig Aird .

44

257. Stacsavat ... 66

314. an Nostarie

44

258, Threipmuir ... 66

315. Anchenreoch .

44

259. Castle (Bladenoch) . . 65

316. Dochard ....

44

260. Gartmorn ... 65

317. Hoglinns

44

261. Raoinavat ... 65

318. Langavat (Benbecula)

44

262. Dhugaill (Torridon) . 63

319. Burga ....

43

263. Braigh Horrisdale . . 62

320. Gainmheich (North)

43

2o4. Liath .... 62

321. Monikie (South)

43

265. a' Bhaillidh . . .61

322. na Sreinge

43

266. an Stromore ... 61

323. Koer .... 43

267. Sealbhag . . • . j 61

324. Shurrery ... 43

268. a' Ghlinne-Dorcha . . 60

325. an Diina ... 41

269. Coire nam Meann . .60

326. Fleet .... 41

270. nam Breac Dearga .

60

327. Kinord .... 41

271. Skene(Dee) .

60

328. Kirbister . . . 41

272. na Moine Buige

59

329. Loyne (West) . . . ! 40

273. an Eilein (Gairloch) .

58

330. na Moracha . . . 1 39

274. Finlas ....

58

331. Poulary . . . .39

275. Rosebery

58

332. Callater .... 38

xlii THE FRESH-WATER LOCHS OF SCOTLAND

TABLE V — continued

Loch.

Volume
in
Million
Cubic
Feet.

Loch.

Volume
in
Million
Cubic
Feet.

333. Deoravat

38

390. Monzievaird .

24

334. Gown (South) .

38

391. na Deighe fo Dheas .

24

335. ic Colla ....

38

392. an Lagain

23

336. na Ceithir Eileana .

38

393. Araich-Lin

23

337. nam Faoileag .

38

394. Crunachan

23

338. St John's

38

395. Ghuiragarstidh

23

339. a'Bhuird

37

396. Lunn da-Bhra .

23

340. Eye ....

37

397. na Beithe

23

341. Hosta ....

36

398. na Lairige

23

342. Mill ....

36

399. Sloy ....

23

343. Druim Suardalain .

35

400. Sron Smeur

23

344. Morsgail ....
345. an Diiin (N. Uist) .

35
34

401. Balgavies
402. Beannach (Gruinard)

22
22

346. Bhradain

34

403. Bhac ....

22

347. Fiart ....

34

404. Burntisland

22

348. Linlithgow

34

405. Castle Semple .

22

349. nan Eun (Tay)

34

406. Black (Etive) (East) .

21

350. Peppermill

34

407. Heilen ....

21

351. Chaluim ....

33

408. Scarmclate

21

352. Holl ....

33

409. Drummond

20

353. an Droighinn .
354. Droma ....

32
32

410. Kinghorn
411. na Claise Fearna

20
20

355. Fingask ....

32

412. Oban a' Chlachain .

20

356. Gelly ....

32

413. Veiragvat

20

357. Long ....

32

414. Airidh na Lie .

19

358. More (Thurso)

32

415. Broom ....

19

359. Sguod ....

32

416. Cuil na Sithe .

19

360. Achanalt

31

417. Eileach Mhic' ille Riabhaich

19

361. Carlingwark .

31

418. Harrow ....

19

362. Cro Criosdaig .

31

419. Lochinvar

19

363. Crombie Den .

31

420. Awe (Inver)

18

364. Fender ....

31

421. na Moine

18

365. Harperleas

31

422. Uanagan '

18

366. Howie ....

31

423. Black (Etive) (Mid) . . 17

367. White of Myrton

30

424. Muckle Lunga . . . 17

368. Craggie ....

30

425. Oban nam Fiadh

17

369. Harelaw ....

30

426. Ree ....

17

370. Hermidale

29

427. Whitefield

16

371. Hoil ....

29

428. Bradan ....

16

372. Kilchoan (Upper) .
373. Tankerness

29
28

429. Eigheach
430. Gleann a' Bhearraidh

16
16

374. an Losgainn Mor

27

431. Kilchoan (Lower) . .16

375. Breaclaich

27

432. Kilconquhar .

16

376. Snarravoe

27

433. Leodsay

16

377. Vatandip

27

434. North-house .

16

378. Dornal ....

26

435. Valtos ....

16

379. Heouravay

26

436. a' Chonnachair . . 15

380. Kilcheran

26

437. a'Vullan

15

381. Monikie (North)

26

438. Birka ....

15

382. nan Druimnean

26

439. Kirk ....

15

383. Olavat ....

26

440. nan Eun (Ness)

15

384. Funds ....

26

441. a' Bhainne

14

385. an Tuirc ....

25

442. Gown (North) .

14

386. Davan ....

25

443. Anna

13

387. Syre ....

25

444. Beag ....

13

388. Ceo-Glas . ...

24

445. Bran ....

13

389. Lindores . . .

24

446. Bruadale

13

STATISTICAL TABLES

xliii

TABLE V — continued

Loch.

Volume
in
Million
Cubic
Feet.

Loch.

Volume
in
Million
Cubic
Feet.

447. Drumlamford .

13

505. na Doire Daraich . . 7

448. Hostigates

13

506. na Gealaich . . . 7

449. Littlester

13

507. Shechernich . . . j 7

450. Lochenbreck .

13

508. Spvnie . . . . ; 7

451. nah-Ealaidh .

13

509. Wester .... 7

452. Skaill ....

13

510. a'Buaille ... 6

453. Auchenchapel .

13

511. an Dubh (Lochy) . . 6

454. Bad & Chrotha

12

512. Dallas . . . -6

455. Cuil Airidh a' Flod .

12

513. Hightae Mill . . . \ 6

456. Derclach.

12

514. na Bi . . . 6

457. Geal ....

12

515. na Garbh-Abhuinn . . 6

458. Kirk Dam

12

516. nan Aiiscot . . . 6

459. na Coinnich

12

517. Monk My re . . .1.6

460. Tormasad

12

518. Loch on Eilean Subhainn . 6

461. a' Chlachain (Lewis)

11

519. Bogton .... 5

462. Burraland

11

520. Brouster .... 5

463. Clickhimin

11

521. Brow .... 5

464. Eldrig . . . . 11

522. Isbister . . . . : 5

465. Mama ....

11

523. Kinellan . . . 5

466. na Beiste

11

524. Kirriereoch

5

467. na Stainge

11

525. Lure ....

5

468. nan Garbh Chkchain

11

526. nan Gabhar

5

469. Peerie ....

11

527. nan Hath . . . 5

470. Aboyne ....

10

528. Pitlyul . . . . j 5

471. Allan ....

10

529. Sabiston ....

5

472. Aslaich ....

10

530. Stormont

5

473. Black (Etive) (West)

10

531. an t-Seasgain .

4

474. Con (Tay)

10

532. Crann ....

4

475. Dochart ....

10

533. Duddingston .

4

476. Essan ....

10

534. Grass ....

4

477. Gamhna ....

10

535. Maol a' Choire .

4

478. nah-Eaglais .

10

536. Tutach ....

4

479. nan Geireann .

10

537. Blairs ....

3

480. Tarruiim an Eithir .

10

538. Cornish ....

3

481. AiriJh na Ceardaich .

9

539. Duartmore

3

482. an lasgaich

9

540. Magillie ....

3

483. Laide ....

9

541. na Garbh-Abhuinn Ard

3

484. Lochnaw

9

542. Scolv ....

3

485. Lundie (Clunie)

9

543. a'Chladaich .

2

486. Moraig ....

9

544. an Tairbeirt Stuadhaich .

2

487. Muck .... 9

545. Black (Tay) .

2

488. Rae .... 9

546. Brough ....

2

489. Sandy .... 9
490. Flugarth ... 8

547. Buidhe(Tay) .
548. Choire ua Cloich

2
2

491. Fvntalloch ... 8

549. Dubh (Etive) .

2

492. Mine' ille Riabhaich . 8

550. Dubh (Xess) .

2

493. na Craige ... 8

551. na Creige Leithe

2

494. Skae . . . . ' 8

552. Rainbow ....

2

495. White (Tay) ... 8

553. Sior ....

2

496. a' Chaoruinn . . .7

554. Tilt ....

2

497. Asta .... 7

555. nan Losganan .

1

498. Bosqnoy ... 7

556. Sand ....

1

499. Clubbi Shuns . . 7

557. Uaine . . . . 07

500. Collaster . . 7

558. Dubh (Forth) . . . 0'6

501. Cults .... 7

559. Setter . . . . ! 0'6

502. Dhomhnuill Bhig . . 7

560. Dhu (Portsonachan) . . 0'5

503. Fithie .... 7

561. St Margaret's ... 0'4

504. Moor Dam ... 7

562. AlltnaMult . . . O'l

xliv

THE FRESH -WATER LOCHS OF SCOTLAND

TABLE VI

FRESH- WATER LOCHS OF SCOTLAND (SOUNDED BY THE LAKE SURVEY)
SHOWING SUMMARY OF PHYSICAL RESULTS

Volume

Drainage Area.

Basins.

Number Number
of ofSound-
Lochs. ings.

in
Million
Cubic

TToof

Area
of Lochs
in Square
Miles.

Total
in Square

Ratio to
Area of

j: eeu.

Miles.

Lochs.

Forth .

13

3,825

36,543

17-02

227-66

13-38

Tay ....

59

6,851

151,353

39-81

1099-52

27-62

Inver, Roe, Kirkaig, Polly,

Garvie . . . .

21

2,540

20,355

12-64

150-44

11-9

Morar .... 3

1,284

82,686

10-99

65-63

6-0

Ewe ....

14

2,473

44,530

14-80

185-51

12-5

Shiel, Ailort, nan Uamh .

6

1,191

28,967

8-58

99-97

11-65

Conou ....

16

2,188

29,850

11-65

366-33

31-5

Shin ....

11

1,564

14,538

12-11

239-69

19-8

Naver, Borgie, Kinloch,

Hope ....

11

1,409

15,615

11-06

239-46 21-7

Beauly ....

13 841

11,227

576

215-26

37-4

Lochy ....

12 2,570 85,855

19-88

293-42

14-8

Ness ....

33 4,385

280,923

34-25

689-14 20-1

Brora, Helmsdale .

11 700

2,756

6-68

202-89 30-4

Wick, Wester, Heilen,

Dunnet, Thurso, Forss i 9 681

1,319

4-82

168-25 34-9

Laxford, Scourie, Badcall,

Duartmore .

10 994 6,679

3-35

59-20 177

Broom, Gruinard

11 1,141

11,312

7-10 111-50 15-7

Gairloch, Torridon, Carron

12 1,098

4,921

3-90 98-46

25-2

Alsh, Aline, Leven .

10

570

2,067

2-51

85-25

33-9

Oban, Feochan, Seil, Mel-

fort ....

13

855

1,328

1-66

34-03

20-5

Bute, Eachaig .

3

372

2,525

2-07

44-89

21-7

Doon, Girvan, Stinchar,

Ryan, Galdenoch .

13

1,028

1,935

3-40

75-16

221

Luce, Bladenoch, Cree

15

594

427

2-12

35-43

167

Fleet, Dee

13 954

1,951

4-02

298-89

74-4

Urr, Nith, Annan .

14 599

652

1-79

2477

13-7

Tweed, Monikie, Lunan,

Dee, Slains .

16 879

5,762

4-24

121-19

28-6

Spey ....

13

663

2,053

2-63

350-50

133-3

Lossie, Findhorn, Nairn .

10

655

5,179

3-50

42-41 12-1

Lismore, Mull, Benbecula

11 728

5,475

3-75 35-54! 9 '5

Xorth Uist

40 3,751

3,026

8-66 45-29 5'2

Lewis ....

30 2.896

7,409

9-64 151-98 15-8

Orkney .

14 '932

2,321

9-98 90-36

9-1

Shetland.

31 1,707

1,416

5'36 51-89

9-7

Forth (Reservoirs) .

20 1,065

998

3-07 43-69 14-2

Etive ....

21 2,619 48,451

18-19

307-55

16-9

Clyde ....

7 2,487 93,331

29-00

314-40

10-8

Tay, Linnhe .

3 106 79

0-23

3-51

15-3

562 59,195

1,015,814

f> .Q

340-22

6669-06

19-6

— D y

cubic

miles

INDEX TO THE DESCRIPTIONS AND MAPS OF
THE SCOTTISH FRESH -WATER LOCHS1
SOUNDED BY THE LAKE SURVEY

[The descriptions are bound in Vol. II., the maps in Yols. III., IV., V., and VI.]

Abovne, \

'ol.

II.-

Par1

:IL,

P-

148;

Vol.

V. 1

Plat<

sLII.

Achall,

55

II.

55

II.,

P-

39;

55

V.

55

XV.

Achanalt,

55

II.

55

•5

P-

267;

55

IV.

55

LVIII.

Achilty,

55

II.

55

•5

P-

275;

55

IV.

55

LXI.

Achlaise, na h-

55

II.

55

•5

P-

61;

55

III.

55

XVI.

Achray,

55

II.

55

•5

P-

5;

55

III.

55

V.

Affric,

55

II.

55

•5

P-

336;

55

IV.

55

LXXVIII.

Ailsh,

55

II.

55

I-,

P-

301;

55

IV.

55

LXIX.

Airidh na Cear-

daich,

55

II.

55

II.,

P-

210;

55

VI.

55

LXXX.

Airidh na Lie,

55

II.

55

II.,

P-

211 ;

55

VI.

55

LXXXII.

Airidh Sleibhe,

na h-

55

II.

55

II.,

P-

32;

55

V.

55

XII.

Aithness,

55

II.

55

II.,

P-

238;

55

VI.

55

C.

Allan,

**

II

TT

p

165;

V.

LXIL

A lit an Fhearna,

55

II.

55

II.,

P-

11;

55

V.

55

II.

Allt nah-Airbhe,

55

II.

55

II.,

P-

34;

55

V.

55

XIII.

Allt na Mult,

55

II.

55

II.,

P-

278;

55

VI.

55

CXXIII.

Alvie,

55

II.

55

II.,

P-

157;

55

V.

55

LIX.

Anna,

55

II.

55

II.,

P-

64;

55

V.

55

XXIII.

Aid,

55

II.

55

I-,

P-

15;

55

III.

55

IX.

Arich-Lin,

55

II.

55

II.,

P-

7;

55

V.

55

II.

Arienas,

55

II.

55

II.,

P-

66;

55

V.

55

XXV.

Arkaig,

55

II.

55

I.,

P-

359;

55

IV.

55

LXXXIV.

Arklet,

55

II.

55

I.,

P-

5;

55

III.

55

IV.

Arthur,

55

II.

55

II.,

P-

125;

55

V.

55

XLIII.

Ashie,

55

II.

55

I,

P-

412;

55

IV.

55

XCII.

Aslaich,

55

II.

55

t,

P-

401;

55

IV.

it

CI.

Assynt,

55

II.

55

L,

P-

148;

55

III.

55

XXXV.

Asta,

55

II.

55

II,

P-

244;

55

VI.

55

cm.

Auchenchapel,

55

II.

55

L,

P-

122;

55

III.

55

XXXIII.

Auchenreoch,

55

II.

55

II.,

P'

124;

55

V.

55

XLIII.

Auscot, nan

55

II.

55

II.,

P-

178;

55

VI.

55

LXVIII.

Avich,

55

II.

55

II.,

P-

276;

55

VI.

55

CXXII.

1 The spelling of the names of the lochs is uniform with that used in the 6-inch
Ordnance Survey maps.

xlv

xlvi

THE FRESH- WATER LOCHS OF SCOTLAND

Awe (Etive Vol. II. Part II., p. 270 ; Vol. VI. Plates CXXII. and

basin), CXXIII.

Awe (Inver

basin),

II.

I., p. 152 ; „ III. Plate XXXVI.

Ba (Mull),

„

II.

55

II,

P-

175;

„ v.

„

LXVI.

Ba (Tay basin),

55

II.

55

I,

P-

62;

„ HI.

?,

XVI.

Bad a? Chrotha,

5,

II.

?9

H,

p.

57;

5, V.

5,

XVIII.

Bad a' Ghaill,

55

II.

55

I,

P'

17;

„ HI-

55

XLL

Bad an Sgalaig,

55

II.

5,

II,

P-

53;

„ v.

55

XVIII

Baddanloch,

„

II.

,5

II,

10;

„ v.

55

II.

Baile sC Gho-

bhainn,

5,

II.

55

H,

P-

171;

„ v.

5,

LXV.

Balgavies,

55

II.

,,

H,

p.

144;

55 V.

„

LI.

Beag,

5*

II.

,,

I,

P-

394;

„ iv.

XCIX.

Beannach (Gruin-

ard basin),

5,

II.

,5

H,

P-

44;

„ v.

55

XVII.

Beannach (In-

ver basin),

55

II.

,,

I,

P-

153;

„ III.

5,

XXXVI.

Beannachan,

55

II.

5,

I,

P-

273;

„ iv.

LVIII.

Beinn sC Mhea-

dhoin,

,,

II.

,,

I,

P-

338;

„ iv.

„

LXXIX.

Beinne Baine, na

,5

II.

,,

I,

P-

340;

„ iv.

„

LXXXII.

Beiste, na

55

II.

„

H,

P-

46;

„ v.

„

XVII.

Beithe, na

55

II.

5,

H,

P-

279;

., VI.

„

CXXXI.

Benachally,

55

II.

„

I,

P-

121;

„ III.

„

XXXIII.

Benisval,

55

II.

„

H,

P-

218;

„ VI.

55

LXXXIX

Beoraid,

5,

II.

,5

I,

P-

206;

„ III.

55

XLIV.

Bhac,

„

II.

•5

I,

P-

94;

„ III.

55

XXVIII.

Bhaid Daraich, a"*

„

II.

55

II,

P-

30;

„ v.

?,

XL

Bhaid - Luach-

raich, sC

5,

II.

,,

I,

P-

228;

„ III.

,,

L.

Bhaillidh, a'

55

II.

,,

II,

P-

68;

„ v.

55

XXVI.

Bhainne, sC

55

II.

55

I,

P-

391;

„ iv.

55

XCVL

Bharpa, sC

II.

55

H,

P.

200;

„ VI.

LXXI.

Bhealaich, sC

(Alsh basin),

5,

II.

55

H,

P-

63;

„ v.

5,

XXIV.

Bhealaich, sC

(Gairloch

basin),

„

II.

55

H,

P-

54;

v.

55

XIX.

Bhealaich, a'

(Naver basin),

55

II.

55

I.

P-

312;

„ iv.

„

LXXIII.

Bhradain,

55

II.

5,

II.

P-

156;

„ v.

^

LVIII.

Bhraoin, a"

55

II.

„

II.

P-

38;

„ v.

?i

XIV.

Bhuird, a"

55

II.

„

II.

P-

186;

5, VI.

,,

LXX.

Bi, na

55

II.

„

II.

P-

275;

„ VI.

n

CXXVI.

Birka,

55

II.

55

H,

P-

236;

„ VI.

55

XCVIII.

Black (Etive

basin),

,5

II.

5,

IL,

P-

279;

„ VI.

55

CXXX.

INDEX TO THE DESCRIPTIONS AND MAPS xlvii

Black (Ryan

basin),

Vol.

II.

Part

II.

,

P-

100;

Vol.

V.

Plate

XXXVIII.

Black (Tay

basin),

55

II.

55

I.

5

P-

109;

55

III.

55

XXX.

Blairs,

55

II.

55

II.

5

p.

166;

55

V.

55

LXII.

Boardhouse,

55

II.

55

II.

5

P-

227;

55

VI.

55

XCIII.

Bodavat.

55

II.

55

II.

5

P-

219:

55

VI.

55

LXXXIX.

Bogton,

„

II.

55

II.

5

94;

55

V.

55

XXXVI.

Borralan,

55

II.

55

I.

,

P-

160;

55

III.

55

XXXVI.

Bosquov,

55

II.

55

II.

5

P-

225;

55

VI.

55

XC.

Bradan,

55

II.

55

II.

•

P-

97;

55

V.

55

XXXVII.

Braigh H orris -

dale,

55

II.

55

II.

5

P-

56;

55

V.

55

XVIII.

Bran.

55

II.

55

L

5

410;

55

IV.

55

XCI.

Breac, nam

55

II.

55

II.

5

P-

29:

55

V.

55

X.

Breac Dearga,

nam

55

II.

55

L

5

P-

399;

55

IV.

55

XCI.

Breaclaich,

55

II.

55

I.

5

P-

90;

55

III.

55

XXVII.

Broom,

55

II.

55

I.

5

P-

89;

55

III.

55

XXVII.

Brora,

55

II.

55

II.

5

P-

1;

55

V.

55

I.

Brough,

55

II.

55

II.

5

245;

55

VI.

55

xcv.

Brouster,

••

II.

55

II.

5

P-

240;

55

VI.

55

CI.

Brow,

M

II.

55

II.

5

244;

55

VI.

55

CIV.

Bruadale.

55

II.

55

II.

5

P-

212;

55

VI.

55

LXXXIII.

Buaille, a"

55

II.

55

II.

•

P-

200;

55

VI.

55

LXX.

Buidhe (Fleet

basin),

55

II.

55

I.

•

P-

304;

55

IV.

55

LXX.

Buidhe (Taj-

Basin),

55

II.

55

I.

5

p.

60;

55

III.

55

XVI.

Builg,

55

II.

55

II.

5

P.

159;

55

V.

55

LXI.

Bunacharan,

55

II.

55

I.

5

P-

348:

55

IV.

55

LXXXII.

Burga,

55

II.

55

II.

5

P-

241;

55

VI.

55

CI.

Burnt island,

55

II.

55

II.

5

P-

255 :

55

VI.

55

CXVI.

Burraland,

55

II.

55

II.

«

P-

234;

55

VI.

55

XCVIL

Butterstone,

55

II.

55

I.

5

n.

102:

55

III.

55

XXIX.

Calavie,

55

II.

55

I.

5

p.

344:

55

IV.

55

LXXXII.

Calder,

55

II.

55

II.

5

P-

21:

55

V.

55

VII.

Callater,

55

II.

55

II.

5

146:

55

V.

55

LII.

Cam,

55

II.

' 55

L

5

P-

161:

55

III.

55

XXXVIII.

Caol na Doire,

55

II.

55

II.

5

154;

55

V.

55

LVI.

Caravat,

55

II.

55

II.

5

P-

196;

55

VI.

55

LXXV.

Carlingwark,

55

II.

55

II.

«

p.

120:

55

V.

55

XLIV.

Castle (Annan

basin),

55

II.

55

II.

5

p.

131 ;

55

V.

55

XLVII.

Castle (Blade-

noch basin),

55

II.

55

II.

5

P.

107:

55

V.

55

XLI.

Castle Semple,

55

II.

55

II.

5

p.

267;

55

VI.

55

cxxxm.

Ceithir-

Eileana, na

55

II.

55

II.

•

P-

199;

55

VI.

55

LXXV.

xlviii THE FRESH- WATER LOCHS OF SCOTLAND

Ceo-Glas, Vol

. II.

Part IL,

P-

167;

Vol

. V.

Plate LXIV.

Chaluim,

55

II.

55

I.,

P-

321;

,,

IV.

55

LXXVL

Chaoruinn, a"*

55

II.

„

II.,

P-

80;

55

V.

55

XXXI.

Chlachain, a'

(Lewis),

55

II.

,,

II.,

P-

211 ;

55

VI.

55

LXXXI.

Chlachain, a'

(Nairn basin),

55

II.

„

II.,

p.

169;

55

V.

55

LXIV.

Chladaich, sC

55

II.

55

II.,

P-

195;

5,

VI.

„

LXXV.

Chlair, sC (Helms-

dale basin),

55

II.

5,

II.,

P-

9;

55

V.

55

II.

Choire, sC

,5

II.

,,

L,

P-

410;

55

IV.

5,

CV.

Choire na

Cloich,

55

II.

,5

IL,

P-

278;

55

VI.

55

CXXIIL

Chon (Forth

basin),

55

II.

55

I-,

P-

13;

55

III.

55

VIII.

Chonnachair, a'

55

II.

,5

IL,

p.

200;

55

VI.

55

LXXVII.

Chroisg, a"

55

II.

55

I.,

P-

263;

55

IV.

,5

LVII.

Chuilinn, a1

(Conon basin),

55

II.

55

L,

P-

267;

55

IV.

,5

LVIII.

Clair (Ewe

basin),

,5

II.

55

I-,

P-

222;

55

III.

,,

XLIX.

Claise Fearna, na

55

IL

55

IL,

P-

28;

„

V.

,,

X.

Clickhimin,

55

II.

55

IL,

p.

234;

55

VI.

55

XCV.

Cliff,

55

II.

5,

IL,

P-

246;

55

VI.

5,

CVI.

Clings,

55

II.

55

IL,

P-

239;

55

VI.

55

C.

Clousta,

55

II.

,,

IL,

P-

238;

55

VI.

55

C.

Clubbi Shuns,

55

II.

55

IL,

p.

235;

55

VI.

55

XCVIII.

Clunie (Ness

basin),

55

II.

„

I-,

p.

395;

55

IV.

55

XCIX,

Clunie (Tay

basin),

55

II.

55

I.,

P-

103;

55

III.

55

XXX.

Coinnich, na

55

II.

5,

IL,

P-

199;

55

VI.

55

LXXV.

Coir" an Fhearna,

55

II.

,5

I.,

P-

313;

55

IV.

55

LXXIII.

Coire nam

Meann,

55

II.

„

II. ,

P-

5;

„

V.

55

II.

Collaster

55

II.

55

IL,

P-

242;

55

VI.

55

C.

Con (Tay basin),

55

II.

55

I.,

P-

95;

55

III.

55

XXVIII.

Cornish,

55

II.

5,

IL,

P-

96;

55

V.

55

XXXVII.

Coulin (Ewe

basin),

55

II.

55

I.,

P-

223;

55

III.

55

XLIX.

Craggie,

55

IL

,,

L,

P-

302;

55

IV.

55

LXIX.

Craige, na

55

II.

,,

I.,

P-

86;

55

III.

55

XXVI.

Craiglush,

55

II.

5,

I>5

P-

100;

55

III.

55

XXIX.

Crann,

55

II.

55

I.,

P-

263;

55

IV.

55

LVII.

Craobhaig, na

55

IL

55

IL,

P-

217;

55

VI.

55

LXXXIX.

Creagach,

55

II.

55

I,

P-

319;

55

IV.

55

LXXV.

Creige Duibhe, na

55

II.

55

L,

P-

256;

55

IV.

55

LVI.

Creige Leithe, na

55

II.

55

IL,

p.

193;

55

VI.

55

LXXV.

Crocach,

55

II.

55

I,

P-

156;

55

III.

55

XXXVII.

Cro Criosdaig,

55

II.

55

IL,

P-

218;

55

VI.

55

LXXXIX.

INDEX TO THE DESCRIPTIONS AND MAPS

xlix

Crogavat. ^

• i

L II.

Part

II.,

P-

194

5

Vol.

VI.

Plate

LXXVI.

Cronibie Den,

5,

II.

55

II.,

P-

142

5

55

V.

55

L.

Crunachan,

„

IL

55

II.,

P-

154

1

55

V.

55

LVL

Cuaich, n a

,,

II.

55

II,

P-

155

5

55

V.

55

LVIL

Cuil Airidh a"

Flod,

5,

II.

55

II.,

P-

210

5

55

VI.

5,

LXXX.

Cuil na Sithe,

„

II.

55

L,

P-

316

5

55

IV.

55

LXXIV.

Cuinne, nan

55

IL

55

II.,

P-

8

5

55

V.

55

II.

Cults,

55

II.

55

II.,

P-

104

1

55

V.

55

XXXIX.

Daimh (Tav

basin).

n

II.

55

L,

P-

92

5

55

III.

55

XXVII.

Daimh, an

(Shin basin),

5,

II.

55

L,

P-

302

•

55

IV.

55

LXIX.

Dallas,

,5

II.

55

P-

165

5

5,

V.

,5

LXIL

Damn (Tom-

don basin),

55

II.

55

IL,

P-

58

*

55

V.

55

XX.

Da van.

,5

II.

55

II.,

P-

148

;

55

V.

55

LIV.

Deaspoirt, nan

55

II.

55

II.,

P-

210

;

,5

VI.

55

LXXX.

Dee,

55

II.

55

IL,

P-

114

•

55

V.

?5

XLIV.

Dee (Expan-

sions of River),

55

II.

„

II.,

P-

119

;

„

V.

55

XLV.

Deighe fo Dheas,

-

na

55

II.

55

IL,

P-

179

;

5,

VI.

5?

LXVIIL

Deoravat,

55

II.

55

IL,

P-

186

5

' 55

VI.

55

LXX.

Derclach,

,5

II.

55

II,

P-

93

;

5,

V.

55

XXXV.

Derculich,

5,

IL

55

1-5

P-

83

;

55

III.

55

XXVI.

Dhomhnuill

Bhig,

55

II.

55

IL,

P-

210

;

55

V.

55

LXXX.

Dhti (Portso-

nachan Hill),

55

II.

55

IL,

P-

278

;

55

VI.

55

CXXIII.

Dhugaill (Tor-

ridon basin),

55

II.

55

IL,

P-

58

•

55

V.

55

XX.

Dhughaill (Car-

ron basin),

55

II.

55

IL,

P-

60

•

55

V.

„

XXII.

Dibadale,

II

II

P

t?17

.

VI.

LXXXVII.

Dilate,

55

II.

55

P-

247

;

55

IV.

55

LIV.

Dithreibh. an

55

II.

55

L,

P-

322

i

55

IV.

55

LXXVI.

Dot-hard,

55

II.

55

IL,

P-

274

•

5,

VI.

55

CXXVII.

Dochart.

55

II.

55

L,

P-

74

*

„

III.

5,

XX.

Doine.

5,

II.

55

L,

P-

9

"

III.

55

VII.

Doire Daraich,

na

II

I

1.V4-

.

III.

XXXVI.

Doire nain Mart.

,,

II.

55

IL,

P-

66

i

,5

V.

55
5,

XXV.

Doon.

55

IL

55

IL,

P-

91

J

55

V.

55

XXXIV.

Dornal,

„

II.

55

II.,

P-

109

55

V.

55

XLIL

Drainc, an

5,

II.

5,

L,

P-

231

*

55

III.

55

L.

Droighinn. an

55

II.

,5

IL,

P-

277

;

55

VI.

55

CXXIII.

Droma,

55

II.

55

IL,

P-

38

*

55

V.

55

XV.

Druimnean. nan

55

II.

55

IL,

P-

80

•

55

V.

55

XXXI.

d

THE FRESH-WATER LOCHS OF SCOTLAND

Druim Suarda-

lain,

Vol.

II.

Part

I

P'

153 • 1

M

TIT

Plate

XXXVI.

Drumellie,

„

II.

L,

P-

105;

55

III.

XXX.

Drumlamford,

,5

II.

„

II,

P-

98;

55

V.

55

XXXVII.

Drummond,

55

II.

„

L,

P-

119;

55

III.

55

XXXII.

Drunkie,

55

II.

„

L,

P-

8;

55

III.

5,

V.

Duartmore,

55

II.

„

II,

P-

35;

55

V.

M

XIII.

Dubh (Etive

basin),

55

II.

M

II,

P-

273;

55

VI.

5,

CXXVI.

Dubh (Forth

basin),

55

II.

„

L,

P-

14;

55

III.

5,

VIII.

Dubh (Gair-

loch basin),

55

II.

„

II,

P-

52;

55

V.

„

XVIII.

Dubh (Gruin-

ard basin),

55

II.

,,

II,

P-

43;

55

V.

55

XVII.

Dubh (nan

Uamh basin),

55

II.

55

L,

P-

253;

55

IV.

55

LVI

Dubh (Ness

basin),

55

II.

55

I,

]).

401;

55

IV.

55

XCI.

Dubh, an

(Lochy basin),

55

II.

55

L,

P-

371;

55

IV.

55

LXXXIX.

Dubh -Mor,

55

II.

55

II,

P-

79;

55

V.

5,

XXXI.

Duddingston,

55

II.

55

II,

P-

252;

55

VI.

55

ex.

Duiri, an (Spey

basin),

„

II.

55

II,

P-

155;

55

V.

55

LVII.

Duin, an (N.

Uist),

„

II.

55

II,

P

191;

55

VI.

55

LXXIII.

Duna, an

„

II.

55

II,

P-

212;

55

VI.

55

LXXXIV.

Dungeon,

55

II.

55

II.,

P-

117;

55

V.

55

XLIV.

Dun na Seil-

cheig,

55

II.

55

II,

P-

167;

55

V.

55

LXIV.

Eaglais, na h-

55

II.

55

II.,

P-

261;

5,

VI.

5,

CXX.

Ealaidh, na h-

55

II.

55

II,

P-

26;

,5

V.

5,

VIII.

Earba, na h-

55

II.

55

I,

P-

362;

„

IV.

„

LXXXV.

Earn,

55

II.

55

L,

P-

75;

55

III.

„

XXII.

Eck,

55

II.

55

II,

P-

87;

55

V.

,,

XXXIII.

Ederline,

II.

II.

n.

275 ;

VI

CXXII.

Edgelaw,

5,

II.

55

IL,

P-

252;

55

VI.

CVIII.

Eela,

„

II.

55

II,

P-

237;

„

VI.

,,

XCIX.

Eigheach

II.

I,

P-

67;

M

III.

XVIII.

Eilde Mor,

„

II.

5,

II,

P-

70;

55

V.

„

XXVII.

Eileach Mhic

'ille Riabhaich

, ,,

II.

,,

II,

P-

45:

55

V.

55

XVII.

Eilein,an(Gair-

loch basin),

„

II.

,5

II,

!>•

49;

55

V.

55

XVIII.

Eilein, an (Spey

basin),

„

II.

5,

II,

P-

158;

„

V.

5,

LX.

Eilt,

„

II.

,5

I,

l>-

249;

„

IV.

„

LV.

INDEX TO THE DESCRIPTIONS AND MAPS

li

Eion Mhic Ala-

Eldrig,

T \ /i
99

II.

99

II.

9

I"
P-

104;

99

V.

99

XXXIX.

Ericht,

99

II.

99

L

9

P-

54;

99

III.

99

XII. to XIV.

Essan,

99

II.

99

I.

'9

P-

90;

99

III.

99

XXVII.

Eun, nan (NY^

basin),

99

II.

99

I.

9

P-

406;

99

IV.

99

cm.

Eun, nan (North

Uist),

99

II.

99

II.

">

P«

187;

99

VI.

99

LXXI.

Eun, nan (Tay

basin),

99

II.

99

L

9

P-

99;

99

III.

99

XXVIII.

Eye,

99

II.

99

I.

9

P-

281;

99

IV.

99

LXIV.

Fad,

99

II.

99

II.

9

P-

84;

99

V.

99

XXXII.

Fada (Ewe

basin),

99

II.

,,

L

9

P-

219;

99

III.

99

XLVIII.

Fada (Gruinard

basin),

99

II.

99

II.

9

P-

46;

99

V.

99

XVII.

Fada (North

Uist),

99

II.

99

II.

J

P-

190;

99

VI.

99

LXXII.

Fadagoa,
Fannich,

99

5

II.
II.

99
99

II.
I.

9
9

P-
P-

209;
268;

99
99

V.
IV.

99
99

LXXX.
LIX.

Faoileag, nani

99

II.

99

II.

9

P-

208;

99

VI.

99

LXXX.

Fender,

99

II.

99

I.

,

P-

115;

99

III.

J9

XXXI.

Fiart,

99

II.

99

II.

9

P-

172;

99

V.

99

LXV.

Fingask,

99

II.

99

I.

,

P-

107;

99

III.

99

XXX.

Finlas,

99

II.

99

II.

9

P-

93;

99

V.

99

XXXV.

Fiodhaig,

99

II.

99

I.

9

P-

299;

99

IV.

99

LXVIII.

Fionn (Gruin-

ard basin),

99

II.

99

II.

)

P-

42;

99

V.

99

XVII.

Fionn (Kirkaig

basin),

99

II.

99

I.

9

P-

166;

99

III.

99

XXXVIII.

Fithie,

99

II.

99

II.

?

P-

143;

99

V.

99

LI.

Bitty,

99

II.

99

II.

9

P-

256;

99

VI.

99

CXVI.

Fleet,

99

II.

99

II.

•

113;

99

V.

99

XLVI.

Flugarth,

99

II.

99

II.

9

P-

236;

99

VI.

99

XCIX.

Forfar,

II

I

P

124;

III.

XXXIII.

Preuchie,

99
99

II.

99

I.

«

P-

113;

99

III.

99
99

XXXI.

Prisa,

99

II.

99

II.

9

P-

174;

99

V.

99

LXVII.

Fyntalloch,

99

II.

99

II.

9

P-

106;

99

V.

"

XL.

Gabhar, nan

99

II.

99

L

P-

373;

99

IV.

99

XC.

Gainmheich,

99

II.

99

I.

•

P-

168;

99

III.

99

XXXIX.

Gamhna,

99

II.

99

II.

>

P-

157;

99

V.

99

LX.

Garbh-Abhuinn,

na

99

II.

99

II.

9

P-

189;

99

VI.

99

LXXII.

Garbh-Abhuinn

Ard, na

99

II.

99

II.

>

P-

189;

99

VI.

99

LXXII.

Garbhaig,

99

II.

99

I.

>

P-

221;

99

III.

99

XLVI.

Hi

THE FRESH-WATER LOCHS OF SCOTLAND

Garbh-Clachan,
nan Vol.
Garry (Ness
basin), „

II. Part II,
II. „ I,

P-
P-

193; Vol. VI. Plate LXXV.
389; „ IV. „ XCV.

Garry (Tay

basin),

55

II.

,,

I.,

P-

57 ;

„ III.

„

XV.

Gartmorn,

55

II.

,,

II.,

P-

254;

„ VI.

,5

CXIV.

Garve,

55

II.

55

I.,

P-

277;

„ IV.

55

LXI.

Gead, an

55

II.

55

I-,

P-

345;

„ IV.

LXXXII.

Geal,

55

II.

55

II.,

P-

266;

„ VI.

n

CXXIV.

Gealaich, na

n

II.

55

IL,

P-

278;

„ VI.

n

CXXIII.

Geireann, nan

,5

II.

55

II,

P-

190;

„ VI.

55

LXXIL

Geireann, nan

(Mill),

„

II.

55

II,

P-

192;

„ VI.

11

LXXIV.

Gelly,

w

II.

55

P-

256;

„ VI.

CXVI.

Gh i uragarst idh ,

55

II.

55

L',

P-

227;

„ III.

,,

XLVII.

Ghlinne - Dor -

cha, a'

55

II.

55

II 5

P-

193;

„ VI.

,,

LXXVI.

Ghobhainn, a'

55

II.

55

II,

P-

55;

„ v.

XIX.

Ghriama, a1

5,

IL

55

I.,

P-

298;

„ iv.

,5

LXVIL

Ghuilbinn,

,5

II.

55

I.,

P-

368;

„ iv.

5,

LXXXVIL

Giorra,

55

II.

55

I-,

P-

94;

„ III.

11

XXVII.

Girlsta,

55

II.

55

II,

P-

234;

„ VI.

11

XCVI.

Gladhouse,

55

II.

55

II,

P-

251;

„ VI.

,5

CVII.

Glass,

55

II.

55

I.,

P-

279;

„ iv.

55

LXII.

Gleann a1 Bhear-

raidh,

,5

II.

55

II,

P-

73;

„ v.

55

XXVIII.

Gorm Loch

Mor,

55

II.

55

I.,

P-

300;

„ iv.

55

LXIX.

Gown,

55

II.

55

I.,

P-

265;

„ iv.

55

LVIL

Grass,

55

II.

55

II,

P-

240;

„ VI.

55

CI.

Grennoch,

55

II.

5,

II,

P-

115;

„ v.

55

XLIV.

Grunavat,

55

II.

,,

IL,

P-

214;

„ VI.

55

LXXXVL

Gryfe,

5,

II.

„

II,

P-

267;

„ VI.

55

CXXXIV.

Harelaw,

55

II.

,,

II,

P-

253;

„ VI.

55

CXIL

Harperleas,

55

II.

,,

IL,

P-

257;

„ VI.

n

CXVI.

Harperrig,

55

II.

„

II,

P-

253;

„ VI.

,5

CXI.

Harray,

55

IL

,,

II,

P-

225;

„ VI.

5,

XC.

Harrow,

55

IL

,,

IL,

P-

118;

„ v.

,5

XLIV.

Heilen,

55

II.

„

II,

P-

17;

„ v.

55

V.

Hempriggs,

55

II.

„

II,

P-

15;

„ v.

55

III.

Heouravay,

55

II.

,5

II,

P-

178;

„ VI.

55

LXVIII.

Hermidale,

55

II.

5,

II,

179;

„ VI.

55

LXVIII.

Hightae Mill,

55

II.

55

II,

P-

132;

„ v.

55

XLVII.

Hoglinns,
Hoil,

55
55

II.
II.

55
55

II,
I.,

P-
P-

229;
114;

„ VI.

„ III.

55
55

XCIV.
XXXI.

Holl,

55

II.

55

IL,

P-

257;

„ VI.

55

CXVII.

Hope,

55

II.

5,

I-,

P-

324;

,, iv.

55

LXXVIL

Hosta

,,

II.

,5

II,

192;

„ VI.

55

LXXIII.

INDEX TO THE DESCRIPTIONS AND MAPS

liii

Hostigates,

Vol.

II.

Part

II.,

P-

239;

Vol.

VI.

Plate

c.

Howie,

••

II.

99

II.,

P-

126:

55

V.

99

XLVL

Huna.

II.

99

II.,

P-

lcS7:

55

VI.

99

LXXI.

H under,

55

II.

««

II.,

P-

201;

55

VI.

55

LXXVII.

Hundland.

55

II.

99

II.,

P-

228;

55

VI.

55

XCIII.

[asgaich, an

99

II.

99

II..

P-

198;

55

VI.

55

LXXV.

Ic Colla.

99

II.

99

II.,

P-

198;

55

VI.

55

LXXV.

Inbhir.

99

II.

99

11-9

P-

70;

55

V.

55

XXVI.

lush.

99

II.

99

II.,

P-

156;

55

V.

55

LEX.

Isbister.

99

II.

99

II.,

P-

226;

55

VI.

55

XCI.

lubhair,

95

II.

99

L,

P-

75:

55

III.

55

XX.

Katrine,

55

II.

99

L,

P-

1;

55

III.

55

IV.

Kemp,

55

II.

99

L,

P-

405;

55

IV.

55

XCI.

Ken,

55

II.

99

II.,

P-

119;

55

V.

55

XLV.

Kennard,

55

II.

99

L,

P-

87;

5,

III.

55

XXVI.

Kernsarv.

II.

I

^26 '

Ill

XLVII.

Kilbirnie,

55
59

II.

99
99

II.,

P-

266;

„

VI.

55

CXXXII.

Kilcheran,

99

II.

99

II.,

P-

172:

„

V.

55

LXV.

Kilchoan,

99

II.

99

II.,

P-

81;

55

V.

55

XXX.

Kilconquhar,

..

II.

99

II.,

P-

257:

55

VI.

55

CXVIII.

Killin,

99

II.

99

L,

P-

406;

55

IV.

55

cm.

Kindar,

99

II.

99

II.,

P-

127;

59

V.

55

XLVL

Kinellan,

95

II.

99

L,

P-

278;

55

IV.

55

LXI.

Kinghorn,

55

II.

99

II.,

P-

256 :

55

VI.

55

CXVI.

Kinord,

55

II.

99

II.,

P-

148;

5,

V.

55

LTV.

Kirbister,

55

II.

99

II.,

P-

226;

„

VI.

55

XCII.

Kirk,

55

II.

99

II-,

P-

131;

,5

V.

55

XLVII.

Kirk Dam,

55

II.

99

H.,

P-

84;

55

V.

55

XXXII.

Kirriereoch,

55

II.

99

II.,

P-

109;

„

V.

55

XLII.

Knock ie,

55

II.

99

L,

P-

404;

55

IV.

55

XCI.

I^again, an

(Shin basin).

55

II.

99

L,

P-

304;

55

IV.

55

LXX.

I^aggan (Lochy

basin),

55

II.

99

L,

P-

364;

55

IV.

55

LXXXV.

Laghair, an

55

II.

99

I.,

P-

338;

55

IV.

55

LXXIX.

Laide.

55

II.

99

L,

P-

402;

55

IV.

55

XCII.

Laidon,

55

II.

99

I.,

P-

63:

55

III.

55

XVII.

Laig Aird, an

55

II.

99

II-,

P-

30;

55

V.

55

XL

Lairige, na

55

II.

99

L,

P-

91;

„

III.

99

XXVII.

Langavat

(Benbecula),

59

II.

99

II.,

P-

180;

,5

VI.

99

LXVIII.

Langavat

(Lewis),

99

II.

55

II.,

P-

213;

59

VI.

99

LXXXV.

I^ann, nan

99

II.

55

I.,

P-

405;

95

IV.

99

XCI.

Laoghal,

99

II.

55

I-,

P-

316;

99

IV.

99

LXXV.

Leitir Easaich,

99

II.

55

P-

151;

99

III.

95

XXXV.

liv

THE FRESH- WATER LOCHS OF SCOTLAND

Leitreach, na Vol.

II. Part II.,

P-

63;

Vol,

V. Plate XXIII.

I ,eodsay,

55

II.

55

II.,

P-

193;

55

VI.

55

LXXV.

Leoid, an

55

II.

55

II.,

P-

277;

55

VI.

55

CXXIII.

Leum a1 Chla-

mhain,

55

II.

55

II.,

P-

6;

55

V.

55

II.

Leven,

55

II.

55

L,

P-

18;

55

III.

55

XI.

Liath,

>J

II.

55

I.,

P-

398;

55

IV.

55

CI.

Lindores,

»J

II.

55

II.,

P-

260;

55

VI.

55

CXIX.

Linlithgow,

55

II.

55

II.,

P-

254;

9)

VI.

55

CXIII.

Lintrathen,

55

II.

55

I-,

P-

123;

55

III.

55

XXXIII.

Littlester,

55

II.

55

II.,

P-

246;

55

VI.

55

cv.

Loch,

55

II.

55

I.,

P-

97;

55

III.

55

XXVIII.

Lochaber,

55

II.

55

II.,

P-

127;

55

VI.

55

XLVI.

Lochenbreck,

55

II.

55

II.,

P-

116;

55

V.

55

XLIV.

Lochindorb,

55

II.

55

II,

P-

164;

55

V.

55

LXIII.

Lochinvar,

55

II.

55

II,

P-

118;

55

V.

55

XLIV.

Lochnaw,

55

II.

55

II,

P-

101;

55

V.

55

XXXIX.

Lochrutton,

55

II.

55

II,

P-

127;

55

V.

55

XLVI.

Lochy,

55

II.

55

I.,

P-

356;

55

IV.

55

LXXXIII.

Lomond,

55

II.

55

II,

P-

262;

55

VI.

55

CXXIV. and

cxxv.

Long,

55

II.

55

I.,

P-

111;

55

III.

55

XXX.

Losgainn Mor,

an

55

II.

55

II,

P-

81;

55

V.

55

XXXI.

Losganan, nan

55

II.

55

I.,

P-

407;

55

IV.

55

cm.

Lowes (Tay

basin),

5?

II.

55

I.,

P-

101;

55

III.

55

XXIX.

Lowes (Tweed

basin),

55

II.

55

II,

P-

136;

55

V.

55

XLIX.

Loyne,

55

II.

55

L,

P-

396;

55

IV.

55

C.

Lubnaig,

55

II.

55

L,

P-

11;

55

III.

55

VI.

Luichart,

55

II.

55

I.,

P-

271;

55

IV.

55

LX.

Lundie (by

Clunie),

5?

II.

55

L,

P-

396;

55

IV.

55

XCIX.

Lundie (by

Garry),

55

II.

55

L,

P-

391;

55

IV.

55

XCVI.

Lungard,

5?

II.

55

L,

P-

341;

55

IV.

55

LXXXII.

Lunn da-Bhra,

5?

II.

55

L,

P-

372;

55

IV.

55

XC.

Lure,

55

II.

55

II,

P-

96;

55

V.

55

XXXMI.

Lurgain,

55

II.

55

L,

P-

172;

55

III.

55

XL.

Lyon,

55

II.

55

I,

P-

72;

55

III.

55

XXI.

Maberry,

55

II.

55

II,

P-

106;

55

V.

55

XL.

Magillie,

55

II.

55

II,

P-

103;

55

V.

55

XXXIX.

Mama,

55

II.

55

L,

P-

256;

55

IV.

55

LVI.

Maol a' Choire,

55

II.

55

L,

P-

152;

55

III.

55

XXXVI.

Maree,

55

II.

55

L,

P-

211;

55

III.

55

XLVI. and

XLVII.

Martnaham,

55

II.

55

II,

P-

94;

55

V.

55

XXXVI.

Meide, na

55

II.

55

I.,

P-

309;

55

IV.

55

LXXI.

INDEX TO THE DESCRIPTIONS AND MAPS

Meiklie,

Vol.

II. 1

Part

I

400; ^

l"T»l

TV 1

3lat(

jCII.

Menteith.

II.

55

I.,

P-

16;

55

III.

55

X.

Merkland,

„

II.

55

L,

P-

297:

11

IV.

55

LXVII.

Mhic" Ille Ria-

bhaich,

n

II.

5,

L,

P-

229;

55

III.

5,

L.

Mhiotailt. a1

11

II.

„

I.,

P-

165;

„

III.

,5

XXXVIII.

Mhor (Ness

basin),

11

II.

11

I,

P-

408;

55

IV.

„

CIV.

Mhuilinn, a"

11

II.

11

I«5

P-

347 :

55

IV.

,5

LXXXII.

Micrdale.

11

II.

11

I 5

P-

303;

55

IV.

55

LXX.

Mill.

11

II.

11

II.,

P-

130;

11

V.

55

XLVII.

Milton,

55

II.

11

II.,

P-

125;

11

V.

11

XLIII.

Mochrum,

„

II.

11

II.,

P-

108;

11

V.

11

XLI.

Moine, na

„

II.

11

II.,

P-

11;

11

V.

11

II.

Moine Buige, na

,5

II.

55

II.,

P-

45;

11

V.

11

XVII.

Monar,

55

II.

,5

P-

346;

11

IV.

11

LXXXL

Monikie.

55

II.

55

II."

P-

141;

11

V.

11

L.

Monk Mvre.

55

II.

55

L,

P-

110;

11

III.

11

XXX.

Monzievaird,

55

II.

55

I-,

P-

119;

11

III.

11

XXXII.

Moor Dam,

11

II.

55

ii.,

P-

255 ;

11

VI.

11

cxv.

Moracha, na

11

II.

11

IL,

P-

187;

11

VI.

„

LXXI.

Moraig,

II

T

p

97:

HI.

XXVIII.

Morar,

55

5*5

II.

11

P-

197;

55

III.

,5

XLIII.

More (Laxford

basin),

55

II.

11

IL,

P-

24;

55

V.

„

VIII.

More (Thurso

basin),

55

II.

11

II.,

P-

19;

55

V.

„

VI.

More Barvas,

55

II.

11

II.,

P-

212;

55

VI.

„

LXXXII.

Morie,

55

II.

„

I",

P-

280;

55

IV.

55

LXIII.

Morlich,

„

II.

„

II-,

P-

158;

55

V.

„

LXL

Morsgail,

,5

II.

„

IL,

P-

215;

55

V.

,5

LXXXVII.

Moy,

„

II.

,5

IL,

P-

164;

55

V.

55

LXII.

Muck,

,,

II.

55

IL,

P-

94;

55

V.

55

XXXVI.

Muckle Lunga,

„

II.

„

IL,

P-

236;

5,

VI.

55

XCVIII.

Muckle Water,

11

II.

..

IL,

P-

228:

„

VI.

5,

XCI.

Muick,

11

II.

11

IL,

P-

14(i:

„

V.

55

LIII.

Mullardoch.

11

II.

11

L,

P-

342 ;

„

IV.

55

LXXX.

Nant,

55

II.

11

II.,

P-

27cS:

VI.

„

CXXIII.

Naver,

55

II.

„

P-

311;

„

IV.

„

LXXII.

Nell.

11

II.

11

IL,'

P-

75:

V.

„

XXIX.

Ness,

II

I

i)

381;

IV.

XCI. and XCII.

North-house.

11

II.

11

IL,

P-

241 :

„

VI.

55
55

C.

Nostarie, an

11

II.

11

I-,

P-

207:

„

III.

55

XLV.

Oban sC Chlach-

ain,

..

II.

11

IL,

P-

192;

w

VI.

„

LXXV.

Oban nam

Fiadh,

II

IT

196;

VI.

LXXV.

Obisary,

55

II.

11

IL,

P-

194;

„

VI.

„

LXXVI.

Ivi

THE FRESH-WATER LOCHS OF SCOTLAND

Ochiltree,

Oich,

Oidhche, na h-

Olavat,

Ordie,

Ossian,

Owskeich,

Pattack,

Peerie,

Peppermill,

Phearsain, a'

Phitiulais,

Pitlyal,

Portmore,

Poulary,

Punds,

Quoich,

Rae,

Rainbow,

Rannoch,

Raoinavat,

Raonasgail,

Rath, nan,

Ree,

Rescobie,

Roer,

Rosebery,

Ruathair, an

Ruthven,

Sabiston,
St John's,
St Margaret's,
St Mary's,
Salach Uidhre,

na

Sand,
Sandy,
Scadavay,
Scamadale,
Scarmclate,
Scaslavat,
Scoly,
Sealbhag,
Seasgain, an t-
Seil,
Seilich, an t-

II. ]

Part

II,

p. 107 ; 1

Vol.

V. 1

3late

•XL.

II.

99

I.,

p. 392 :

„

IV.

95

XCVII.

II.

99

II,

p. 51;

„

V.

55

XIX.

II.

99

II,

p. 180 ;

„

VI.

55

LXIX.

II.

99

1-5

p. 85;

„

III.

55

XXVI.

II.

99

L,

p. 366 ;

55

IV.

55

LXXXVI.

II.

99

I-,

p. 174 ;

»

III.

99

XLI.

II.

99

L,

p. 361 ;

fj

IV.

55

LXXXIX.

II.

99

II,

p. 229;

„

VI.

55

XCI.

II.

99

II-,

p. 255 ;

„

VI.

55

cxv.

II.

99

II,

p. 80;

95

V.

55

XXXI.

II.

99

II,

p. 159;

„

V.

55

LX.

II.

99

L,

p. 112;

n

III.

55

XXX.

II.

99

II,

p. 252 ;

„

VI.

55

CIX.

II.

55

1-5

p. 389 ;

99

IV.

55

XCIV.

II.

55

II,

p. 237 ;

99

VI.

55

XCVII.

II.

55

L,

p. 388 ;

99

IV.

55

xcm.

II.

55

I.,

p. 106 ;

99

III.

99

XXX.

II.

59

II,

p. 278 ;

99

VI.

99

CXXIII.

II.

99

L,

p. 68;

99

III.

99

XIX.

II.

99

II,

p. 213 ;

99

VI.

99

LXXXIV.

II.

99

II,

p. 216 ,

99

VI.

99

LXXXVIII.

II.

99

II,

p. 279 ;

99

VI.

99

CXXXI.

II.

99

II,

p. 104;

99

VI.

99

CXXI.

II.

59

II,

p. 143;

99

V.

99

LI.

II.

99

II,

p. 235 ;

95

VI.

99

XCVIII.

II.

99

II,

p. 251 ;

55

VI.

99

CVIII.

II.

99

II,

p. 4;

55

V.

99

II.

II.

99

L,

p. 411 ;

55

IV.

99

cv.

II.

99

II,

p. 225 ;

99

VI.

99

XCI.

II.

99

II,

p. 18;

99

V.

99

V.

II.

99

II,

p. 252 ;

99

VI.

99

ex.

II.

99

II,

p. 137 ;

99

V.

99

XLIX.

II.

59

II,

p. 69;

99

V.

95

XXVI.

II.

99

II,

p. 150 ;

99

V.

99

LV.

II.

99

II,

p. 223 ;

99

VI.

99

xcv.

II.

99

II.,

p. 188 ;

99

VI.

99

LXX.

II

IT

p. 76;

V

XXIX.

II.

55

II,

p. 14;

55

V.

99

III.

II.

59

II,

p. 217;

55

VI.

55

LXXXVIII.

II.

55

I.,

p. 84;

55

III.

95

XXVI.

II.

55

L,

p. 343 ;

5J

IV.

,9

LXXX.

II.

99

II,

p. 198 ;

55

VI.

55

LXXV.

II.

55

II,

p. 77;

55

V.

55

XXX.

II.

59

II,

p. 156;

59

V.

55

LVIII.

INDEX TO THE DESCRIPTIONS AND MAPS

Ivii

Setter,

Vol.

II.

Part

II.

'9

P-

245 ;

Vol.

VI.

Plate

xcv.

Sgamhain,

99

II.

95

II.

•

P-

60;

99

V.

99

XXI.

Sguod,

99

II.

59

I.

9

P-

230;

59

III.

99

L.

Sheallag, na

99

II.

99

II.

«

P-

40;

99

V.

99

XVI.

Shechernich.

99

II.

99

I.

9

P-

122 ;

99

III.

99

XXXIII.

Shiel,

99

II.

99

I.

9

P-

241;

99

IV.

99

LII, LIII.

Shin.

99

II.

99

I.

9

P-

293;

,9

IV.

99

LXV, LXVI.

Shurrerv.

99

II.

55

II.

9

P-

20;

99

V.

55

VII.

Si or.

99

II.

55

II.

,

P-

278;

99

VI.

55

CXXIX.

Skae.

99

II.

55

II.

,

P-

126;

99

V.

55

XLVI.

Skaill,

99

II.

59

II.

,

P-

228;

99

VI.

55

XCIV.

Skealtar,

99

ii.

99

II.

9

P-

189;

99

VI.

55

LXXII.

Skebacleit,

99

n.

99

II.

9

P-

206;

99

VI.

55

LXXVIII.

Skeen (Annan

basin),

99

n.

99

II.

9

P-

129;

. 99

V.

59

XLVII.

Skene (Dee

basin. Aber-

.

deen ),

99

ii.

99

II.

,

P-

149:

99

V.

99

LII.

Skeirow,

99

n.

99

II.

,

P-

115;

99

V.

95

XLIV.

Skiach,

99

ii.

99

I.

,

P-

88;

99

III.

55

XXM.

Skinaskink, .

99

n.

99

I.

J

P-

169;

99

III.

55

XXXIX.

Slagain, an t-

M

n.

99

I.

,

P-

230;

99

III.

55

L.

Sloy.

99

ii.

99

II.

9

P-

266;

99

VI.

55

CXXIV.

Snarravoe,

99

ii.

99

II.

9

P-

247:

99

VI.

55

cv.

Soul seat,

99

n.

99

II.

•

P-

103;

99

V.

55

XXXIX.

Spiggie,

99

ii.

99

II.

9

P-

244:

99

VI.

59

CIV.

Spynie,

99

ii.

99

II.

9

P-

162;

99

V.

99

LV.

Sreinge, na

99

n.

99

II.

•

P-

75 :

99

V.

99

XXVIII.

Sron Sineur,

99

ii.

99

I.

9

P-

66;

99

III.

99

XVIII.

Staca. an

* 99

n.

99

I.

*

P-

398;

99

IV.

99

CI.

Stack.

99

n.

99

II.

9

P-

27 :

9,

V.

99

IX.

Stacsavat,

99

n.

99

II.

9

P-

215;

99

VI.

99

LXXXVI.

Stainge. na

99

ii.

99

I.

9

P-

60;

99

III.

99

XVI.

Stem

99

n.

99

II.

9

P-

224:

99

VI.

99

xc.

Stormont,

99

n.

99

I.

9

P-

110;

99

III.

99

XXX.

Strandavat.

55

ii.

99

II.

9

P-

207;

99

VI.

99

LXXIX.

Strom,

55

n.

99

II.

,

P-

242 :

99

VI.

99

CII.

Strom ore, an

55

ii.

99

II.

*

P-

190 |

99

VI.

99

LXXII.

Suai naval,

59

n.

55

IL,

P-

215;

95

VI.

99

LXXXM.

Subhainn,Loch

on Eilean,

99

n.

59

I.

9

P-

216;

55

III.

99

XLVII.

Swannav.

99

ii.

99

II.

9

P-

227:

59

VI.

99

XCIII.

Syre.

99

ii.

99

I.

9

P-

314;

59

IV.

99

LXXIV.

Tachdaidh, an

99

ii.

59

I.

9

P.

344;

59

IV.

99

LXXXII.

Tairbeirt Stua-

dhaich, an

99

n.

99

II.

9

P-

186;

55

VI.

99

LXX.

Talla,

99

n.

99

II.

9

135;

99

V.

99

XLVIII.

Tankerness,

99

ii.

99

II.

,

P-

226:

99

VI.

99

XCII.

Tarff',

99

n.

99

I.

,

P-

402;

99

IV.

99

XCI.

e

Iviii

THE FRESH-WATER LOCHS OF SCOTLAND

Tarruin an
Eithir, V

ol.

II. I

'art

II

P-

200; ^

^ol

VI F

late

LXX.

Tay,

55

II.

55

L,

P-

80;

55

III.

55

XXIV. and

XXV.

Tearnait,

55

II.

55

II.,

P-

67;

55

V.

55

XXV.

Thorn,

55

II.

55

IL,

P-

267;

55

VI.

55

CXXXIV.

Threipmuir,

55

II.

55

IL,

P-

253;

55

VI.

55

CXII.

Tilt,

55

II.

55

I.,

P-

96;

55

III.

55

XXVIII.

Tingwall,

55

II.

55

II 5

P-

243;

55

VI.

55

cm.

Tollie,

55

II.

55

L,

P-

225;

55

III.

55

XLVII.

Tomain, an

55

II.

55

II,

P-

193;

55

VI.

55

LXXVI.

Tormasad,

55

II.

55

II,

P-

199;

55

VI.

55

LXX I.

Tralaig,

55

II.

55

II,

P-

78;

55

V.

55

XXXI.

Trealaval,

55

II.

55

II,

P-

208;

55

VI.

55

LXXX.

Treig,

55

II.

55

1-5

P-

369;

55

IV.

55

LXXXVIIL

Trool,

55

II.

55

II,

P-

110;

55

V.

55

XLIL

Truid air Sgi-

thiche,

55

II.

55

II,

P-

8;

55

V.

55

II.

Tuirc, an

55

II.

55

L,

P-

157;

55

III.

55

XXXVIL

Tulla,

55

II.

55

II,

P-

274;

55

VI.

55

CXXVIII.

Tummel,

55

II.

55

L,

P-

78;

55

III.

55

XXIII.

Turret,

55

II.

55

L,

P-

117;

55

III.

55

XXXIL

Tutach,

55

II.

55

IL,

P-

165;

5,

V.

55

LXII.

Uaine,

55

II.

55

L,

P-

118;

55

III.

55

XXXIL

Uanagan,

55

II.

55

L,

p.

394;

55

IV.

55

XCVIII.

Urigill,

55

II.

55

L,

P-

160;

55

III.

55

XXXVI.

Urr,

55

II.

55

II,

P-

124;

55

V.

55

XLIII.

Urrahag,

55

II.

55

II,

P-

212;

55

VI.

55

LXXXIII.

Ussie,

55

II.

55

1-5

P-

278;

55

IV.

».

LXI.

Vaara,

55

II.

55

II,

p.

238;

55

VI.

55

C.

Valtos,

55

II.

55

II,

P-

208;

55

VI.

55

LXXX.

Vatandip,

55

II.

55

II,

P-

211;

55

VI.

55

LXXXI.

Veiragvat,

55

II.

55

II,

191;

55

VI.

55

LXXII.

Vennachar,

55

II.

55

I,

P-

6;

55

III.

55

V.

Veyatie,

55

II.

55

P-

163;

55

III.

55

XXXVIII.

Voil,

55

II.

55

I,

P-

9;

55

III.

55

VII.

Vullan, a

55

II.

55

1-5

P-

399;

55

IV.

55

CL

Watten,

55

II.

55

II,

P-

15;

55

V.

55

III.

Wester,

55

II.

55

II,

p.

17;

55

V.

55

IV.

Whinyeon,

55

II.

55

II,

p.

120;

55

V.

55

XLIV.

White (Ryan

basin),

55

II.

55

II,

}>.

100;

55

V.

55

XXXVIII.

White (Tay

basin),

55

II.

55

L.

, p.

108;

55

III.

55

XXX.

White of Myr-

ton,

55

II.

55

IL.

, }>•

105;

55

V.

55

XXXIX.

Whitefield,

55

II.

55

IL.

• P'

104;

55

V.

55

XXXIX.

Woodhall,

55

II.

5,

II,

p.

116;

55

V.

55

XLIV.

VOLUME II

PART I

LOCHS OF THE FORTH BASIN.

WITHIN this basin the following lochs were sounded by Sir John Murray
and the late Mr. Fred. P. Pullar, viz., Lochs Katrine, Arklet, Achray,
Vennachar, Drunkie, Voil, Doine, Lubnaig, Chon, Dubh, Ard,
Menteith, and Leven. The eight first-mentioned lochs belong to the
catchment-basin of the river Teith, and have a special interest from
being directly or indirectly connected with the excellent water-supply
to the city of Glasgow.* Loch Arklet belongs to the catchment-basin
of Loch Lomond, but the Corporation of Glasgow has power to divert
its waters into the catchment-basin of Loch Katrine.

Loch Katrine (see Plate IV.). — Loch Katrine is one of the best
known and most beautiful of the Scottish lochs. The celebrated

* In the year 1855 the Corporation of Glasgow was empowered by Act of Parliament
to raise Loch Katrine 4 feet above, and to draw it down 3 feet below, the previous
summer level, thus giving a total available depth of 7 feet for the supply of water to
the city, the quantity of water to be drawn from the loch being restricted to fifty
million gallons in twenty-four hours. For the purpose of providing compensation water
to the riparian owners on the river Teith, power was also given to raise Loch Vennachar
5 feet 9 inches above its previous summer level, and to draw it down 6 feet, and
also to raise Loch Drunkie 25 feet. An aqueduct was built from the southern shore of
Loch Katrine to Glasgow, 8 feet wide and 8 feet high throughout, with a semicircular
top, and having a fall towards Glasgow of 10 inches per mile. At first only a portion
of the available fifty million gallons per day was conveyed to Glasgow, but by the
end of 1881, the whole of the works necessary to complete the original design were
finished. In the year 1884 it was found necessary to provide a larger quantity of water
in order to keep pace with the growth of the city, and it was then found that the rough-
ness of the rock sides of the aqueduct had a very retarding influence upon the velocity
of the water, and that the aqueduct could not be made to discharge more than forty-two
million gallons per day. Power was subsequently obtained from Parliament to build a
second aqueduct, to raise Loch Katrine an additional 5 feet, and to convert Loch Arklet,
which flows into Loch I omond, into a reservoir by raising it 25 feet in level. These
works are now i i progress, and when completed are estimated to give a supply of
seventy-five millions of gallons of water per day to the city of Glasgow. Should a still
greater supply be necessary in the future, it is believed this can be obtained by connecting
Loch Doine with L«ch Katrine by a tunnel through the intervening hills, and by con-
structing an embankment at the bottom of Loch Doine to raise the water-level 30 feet,
and another at the bottom of Loch Voil to raise the water-level of that loch 10 feet,
and if still more water were wanted, Loch Lubnaig could furnish it (see papers by James
M. Gale, Esq., M. INST. c.B , in the Traits. InsL Engineers in Scotland, vols. vii., xii.,
xxvi.. and xxxviii .. and his Report on the proposed extension of the Glasgow Corporation
Wat.-r \V,,rks. dated May 17. 1884).

U

2 BATHYMETRICAL SURVEY OF

woodland scenery of the Trossachs and Ellen's isle are situated at its
south-eastern end, while splendid moorland scenery prevails at the north-
western end. It has a total length of about 8 miles, with a maximum
width of almost exactly 1 mile between the mouths of Letter burn and
Strone burn on the northern shore to a small bay on the opposite shore.
The mean breadth, obtained by dividing the area of the loch by its
length, is 0'6 mile, or 1056 yards, being 7J per cent, of the length.

The waters of the loch cover an area of 3059 acres (or 4f square
miles), and it drains an area about eight times greater, or about 24,900

FIG. 1. LOCH KATRINE AND ELLEN'S ISLE.

(Photograph by J. Valentine.)

acres (nearly 37 \ square miles). * The total number of soundings taken
in Loch Katrine was 775, an average of 163 per square mile, and the
average depth of these was 142 J feet, the greatest depth observed being
495 feet (82 J fathoms). f The positions of the majority of the soundings
are shown on Plate IV.

* When the waters of I.och Arklet are diverted into Loch Katrine this drainage area
will, of course, be extended.

f As long ago as September, 1812, and September, 1814, Mr. James Jardine, C.E.,
recorded observations on the depth and temperature of Loch Katrine (see Buchan, Proc.
Roy. Soc. Edin., vol. vii. p. 791, 1872). The maximum depth recorded by him is 480
feet (80 fathoms), whereas, as stated above, we found a depth of 495 feet. His tempera-
ture observations are given in the table of serial temperatures, and discussed along with
the recent observations. We believe that Mr. J. Y. Buchanan took soundings and tem-
peratures in Loch Katrine some years ago, but, as far as we are aware, they were
never published, and are therefoi'e not available for discussion (see also Art. " Lake " in
Encycl. Bi-it., 9th edit.).

THE FRESH-WATER LOCHS OF SCOTLAND.

2 <

FIG. 3. CROSS-SECTIOW OF

LOCH KATRINE. THE

BLACK PORTION SHOWS
THE TRUE SLOPES; THE
OUTLINE SHOWS THE
SLOPES EXAGGERATED

TEN TIMES.

The bulk of water con-
tained in the loch is esti-
mated at 27,274,000,000
cubic feet, or about one-
fifth of a cubic mile, and
the mean depth (suppos-
ing the loch to be of
uniform depth over its
present area) at 199 feet
(33 fathoms), the mean
depth being over 40 per
cent, of the maximum depth. The length of the
loch is 85 times the maximum depth, and 211
times the mean depth.

The surface of the loch is, according to the
Ordnance Survey maps, at an elevation of 364
feet above sea-level, so that our survey shows
that a considerable portion of the bottom of
the loch (equal to about 645 acres, or over one
square mile) lies below sea-level, the deepest part
being 131 feet (or 22 fathoms) below the level
of the sea. The area below the level of the
sea is indicated by a red line on Plate IV. In
this respect Loch Katrine differs from the other
lochs referred to in this paper, for in none of them
is the depth sufficiently great to bring any portion
of their bottoms below the level of the sea.

The soundings show that Loch Katrine prac-
tically forms a single basin, not being divided, like
Loch Lomond and Loch Lubnaig, for instance,
into separate basins by any important ridges or
rises on the bottom. The deepest part is in the
centre of the loch, a long narrow depression, with
depths exceeding 400 feet, extending for over 4
miles from opposite Coilachra to opposite Ruinn
Dubh-aird, with a maximum width of over a quar-
ter of a mile ; this 400-f eet depression has an area
of about 515 acres, or 17 per cent, of the entire
superficial area of the loch. The deepest sounding
(495 feet) is situated at the very eastern extremity
of the 400-f eet depression.

The 300-feet depression is over 5 miles in
length, with a maximum breadth of one-third of a
mile ; it extends from off Coilachra to near Ellen's
isle. The area enclosed between the 300-feet and

4 BATHYMETRICAL SURVEY OF

400-feet contour-lines is about 415 acres, or 13 per cent, of the entire
area of the loch.

The 200-feet depression is 5J miles in length and half a mile in
maximum breadth, extending from south of Ellen's isle to near Black
island, where it is separated (by a sounding of 198 feet) from a small
isolated area, lying between Coilachra and Black island, one-third of a
mile in length by nearly one-eighth of a mile broad. The area between
the 200- and 300-feet contours is about 510 acres, or 17 per cent, of the
area of the loch.

There are two 100-feet depressions, the principal one (6 miles in
length) stretching from close to Ellen's isle to Black island, the other

FIG. 4. LOCH ARKLET, LOOKING WEST.

(Photograph by G. W. Wilson.)

extending from Black island towards the point called Rudha nam
Moine, with a total length of over half a mile. The area enclosed
between the 100- and 200-feet contours is about 670 acres, or 22 per
cent, of the area of the loch.

The 50-feet line follows pretty closely the contour of the loch, from
Rudha nam Moine into the eastern arms of the loch at the Trossachs,
running outside of Black island, Ellen's isle, and the small islands near
the shore all round, with a small isolated patch at the junction of the
Trossachs arm with the arm leading to Achray Water; it encloses a
small shallow, with a beacon on it, opposite the entrance of the Glasa-
hoile. The area between the 50- and 100-feet contours is about 400

THE FRESH- WATER LOCHS OF SCOTLAND. 5

acres, or 13 per cent, of the area of the loch, while the area between the
coast-line and the 50-feet contour is nearly 550 acres, or 18 per cent,
of the area of the loch, so that 82 per cent, of the floor of the loch is
covered by over 50 feet of water.

Loch A r filet (see Plate IV.). — Loch Arklet drains into Loch Lomond,
but the corporation of the city of Glasgow have power, by the erection
of a dam at its west end, to divert the waters into the catchment-
basin of Loch Katrine, in order to increase the supply of water to the
city. The surface of this little moorland loch is, according to the
Ordnance Survey maps, 455 feet above sea-level. It has a total length
of over a mile, and a maximum width near the east end of nearly half
a mile. The mean breadth is about one-third of a mile, or 587 yards,
being 33 per cent, of the length. Its waters cover an area of about
210 acres (0'3 square mile), and it drains an area about sixteen times
greater, or about 3400 acres (5J square miles). The number of sound-
ings taken in Loch Arklet was 135, the average depth of these being
21 feet, and the greatest depth observed being 67 feet (11 fathoms).
The mass of water in the loch is estimated at 222,000,000 cubic feet,
and the mean depth at 24 feet, or 36 per cent, of the maximum depth.
The length of the. loch is 79 times the maximum depth, and 218 times
the mean depth.

The wide eastern portion of Loch Arklet is shallower than the
narrower western portion. The 50-feet depression extends little more
than halfway towards the eastern end of the loch, and is slightly under
half a mile in length, the greatest depth (67 feet) being approximately
near the centre of the depression, and nearer the western than the
eastern end. The area of over 50 feet in depth is estimated at about
19 acres, or 9 per cent, of the area of the loch, while the area between
the 50-feet line and the shore is about 191 acres, or 91 per cent, of the
entire superficial area.

Two small islands appear on the chart in the shallower part of the
loch towards the north-eastern end.

Loch Achray (see Plate V.). — This pretty little lake is situated at
the entrance to the Trossachs, and immediately before the windows of
the Trossachs Hotel. Loch Achray, the surface of which is, according
to the Ordnance Survey maps, 276 feet above sea-level, has a total
length of about 1J miles, with a maximum width of nearly one-third of
a mile. The mean breadth is about a quarter of a mile, or 458 yards,
being nearly 21 per cent, of the length. Its waters cover an area of
about 205 acres (one-third of a square mile), and the area draining into
it is twenty-two times greater, or about 4500 acres (7 square miles).
The number of soundings taken in Loch Achray was 171, and the average
depth of these was 36J feet, the maximum depth recorded being 97

6 BATHYMETRICAL SURVEY OF

feet (16 fathoms). The bulk of water contained in the loch is estimated
at 321,000,000 cubic feet, and the mean depth at 36 feet (6 fathoms),
or 37 per cent, of the maximum depth. The length of the loch is 68
times the maximum depth, and 183 times the mean depth.

The 50-feet depression is over two-thirds of a mile in extreme length,
with a maximum width of about one-fifth of a mile, lying uniformly
near the centre of the loch, and covers an area of about 64* acres, or 31
per cent, of the superficies of the loch. Within this area there is a
depression occupying about 32 acres where the depths exceed 90 feet,
the greatest registered depth (97 feet) being recorded in two places
approximately in the centre of the loch. At the west end of the loch,

FIG. 5. LOCH ACHRAY, LOOKING WEST TOWARDS BEN VENUE.

(Photograph by J. Valentine.)

not far from the hotel pier, a detached sounding of 50 feet is recorded ;
off the mouth of the Achray water there are some shallow patches, and
a shallow in the centre of the loch towards the west end, on which there
are 2 to 3 feet of water, is marked by a beacon. The area less than 50
feet in depth is estimated at about 141 acres, or 69 per cent, of the total
area of the loch. The eastern end of the loch is relatively shallow; at
one place there is a depression with 27 feet surrounded by shallower
water, and at another place there is what appears to be a submerged
crannog covered by only 1 or 2 feet of water.

Loch Vennachar (see Plate V.). — Loch Vennachar, the surface of

THE FRESH- WATER LOCHS OF SCOTLAND. 7

which is, according to the Ordnance Survey maps, 270 feet above sea-
level, has a total length of about 4 miles, with a maximum width of less
than three-quarters of a mile. The mean breadth is about two-fifths
of a mile, or 704 yards, being 10 per cent, of the length. Its waters
cover an area of about 1030 acres (or over 1| square miles), and it drains
an area nearly eighteen times greater, or about 18,300 acres (28J square
miles). The total number of soundings taken in Loch Vennachar was
423, an average of 263 per square mile, the average depth of these being
41 feet, and the greatest depth observed being 111 feet (18 \ fathoms),
so that it may be regarded as a relatively shallow loch. The bulk of
water contained in the loch is estimated at 1,903,000,000 cubic feet,
and the mean depth at 42J feet (7 fathoms), being 38 per cent, of the
maximum depth. The length of the loch is 190 times the maximum
depth, and 498 times the mean depth.

FIG. 6. LOCH VENNACHAR, LOOKING SOUTH-WEST.

(Photograph hi/ G. W. Wilton.)

It will be observed from an examination of the map that the loch is
deeper in the eastern than in the western portion, the western end being
shallow and covered with weeds, so that one must proceed nearly a mile
from the west end of the loch before encountering depths of 50 feet,
and this is merely a small patch separated from the principal 50-feet
depression by a distance of nearly two-thirds of a mile. In August the
water in the loch is at its lowest, and the weeds at the west end most
abundant. The principal 50-feet depression is about 2 miles in length,
with a mean breadth of about one-third of a mile and a maximum
breadth of nearly half a mile. It includes two 100-feet depressions : the
first one is very irregular in shape, situated approximately in the centre
of the loch, and contains the greatest observed length (111 feet), which
lies towards the northern shore; the second one occupies the central
portion of the large 50-feet depression, the greatest depth observed

8 BATHYMETRICAL SURVEY OF

therein being 106 feet. Towards the eastern end of the large 50-feet
depression is a small shallow patch in the centre of the loch opposite
Portnellan, in which a depth of 36 feet was found.

At the extreme eastern end are situated the sluices and weir, over
which the compensation water passes into the river Teith; at some
distance from the sluices the depth of water flowing over a weir is
recorded twice a day.

The area between the shore and the 50-feet contour is estimated at
about 635 acres, or 62 per cent, of the entire superficial area of the loch,
while the area between the 50- and 100-feet lines is estimated at about
324 acres, or 31 per cent., and the area with depths over 100 feet is
estimated at about 71 acres, or 7 per cent, of the area of the loch.

Loch Drunkie (see Plate V.). — This picturesque and irregular High-
land loch is shut in on all sides by high hills, is difficult of access, and
rarely visited. The surface of the loch, according to the Ordnance
Survey maps, is 416 feet above the level of the sea, but it was raised 25
feet in connection with the water-supply to the city of Glasgow, with
the view of furnishing compensation water to the river Teith. The
soundings shown on the map give the depth in the loch in April, 1899.

Loch Drunkie is remarkable in many respects. It is the smallest
of the five lochs in the Loch Katrine district, but deeper than the larger
Loch Arklet situated at a similar high elevation, and quite as deep as
the neighbouring Loch Achray situated at a lower elevation. In form
it is peculiar, consisting of a quadrangular portion throwing out three
arms of various sizes in different directions. The largest arm runs in a
north-easterly direction, the extremity approaching within a quarter of
a mile of the southern shores of Loch Vennachar; this arm contains
the greatest depths observed in the loch, and near its extremity the
Ordnance Survey map indicates a small island which was not seen.
The second arm in point of size runs directly west, and contains a
maximum depth of 80 feet. The smallest arm runs in a south-westerly
direction, deepening gradually though irregularly from 6 feet at the
extremity to 15 feet near the junction with the quadrangular body of
the loch.

The maximum length of the loch (between the extremities of the
north-eastern and south-western arms) is over one mile ; from the
extremity of the western arm to the opposite (eastern) shore of the loch
is a little less. The maximum width of the quadrangular body of the
loch is over a quarter of a mile. The mean breadth is 0*21 mile, being
21 per cent, of the length. The waters of the loch cover an area of
about 138 acres (0'22 square mile), and drain an area ten times greater,
or over 1400 acres (2 '2 square miles). The number of soundings taken
in Loch Drunkie was 155, the average depth of these being 38J feet,
the greatest depth observed (exactly the same as in the case of Loch

THE FRESH-WATER LOCHS OF SCOTLAND. 9

Achray) being 97 feet (16 fathoms). The bulk of water contained in the
loch is estimated at 217,000,000 cubic feet, and the mean depth at 36
feet (or 6 fathoms), being 37 per cent, of the maximum depth. The
length of the loch is 54 times the maximum depth, and 147 times the
mean depth.

There are two depressions with depths over 50 feet : one at the
extremity of the western arm, about a quarter of a mile in length,
and the other filling up the greater part of the body of the loch, and
extending some distance up the north-eastern arm, being over one-third
of a mile in length and about one-quarter of a mile in maximum width.
The area over 50 feet in depth is estimated at 43 acres, or 31 per cent.

FIG. 7. LOCHS VOIL AND DOINE, LOOKING WEST FROM EOB ROT S GRAVE, BALQUHIDDEB.

(Photograph by J. Valentine.)

of the total area of the loch, while the area between the shore and the
50-feet contour is estimated at 95 acres, or 69 per cent, of the area of
the loch.

Lochs Voil and Doine. — These two lochs, the surfaces of which,
according to the Ordnance Survey maps, are situated at an elevation of
414 feet above sea-level, formed at no very distant date a continuous
loch, which has been divided into two portions principally by the
deposition of material brought down Monachyle glen by the river ; this
is supported by the fact that deep water extends close up to the dividing
promontory of land on both sides. The former continuous loch must

10 BATHYMETRICAL SURVEY OF

have been over 4J miles in length. As the level of these two lochs is
50 feet higher than the level of Loch Katrine, it has been suggested
by Mr. Gale that the water-supply to the city of Glasgow could, if
necessary, be increased by connecting these lochs to Loch Katrine by
a conduit through the intervening hills.

Loch Voil (see Plate VII.). — Loch Voil has a total length of over
3J miles, with a maximum width (near the western end) of about one-
third of a mile. The mean breadth is about a quarter of a mile, or
422 yards, being 7 per cent, of the length. The waters of Loch Voil
cover an area of about 561 acres (0'88 square mile), and those of Loch
Doine about 135 acres (0'21 square mile), or together over one square
mile, while they drain an area thirty-five times greater, or about 24,600
acres (nearly 38| square miles).

The total number of soundings taken in Loch Voil is 279, the average
depth of these being 39 J feet, and the greatest depth 98 feet (or 16 J
fathoms). The bulk of water contained in the loch is estimated at
1,000,000,000 cubic feet, and the mean depth at 41 feet (or nearly
7 fathoms), being 42 per cent, of the maximum depth. The length of
the loch is 189 times the maximum depth, and 451 times the mean
depth.

Loch Voil becomes narrower and shallower towards the eastern end ;
one must proceed about a mile and a half (or over one-third of the length
of the loch) from the eastern end before encountering depths of 50 feet,
while deeper water is found towards the western end. The 50 -feet
depression extends from quite close to the western end for a distance of
2 miles towards the eastern end of the loch, with a maximum width
of about a quarter of a mile. Towards the western end of the loch is a
considerable area (over half a mile in length by a sixth of a mile in
maximum breadth) having depths greater than 90 feet. In this all the
deepest soundings are situated (the greatest depth, 98 feet, having been
observed in two places). From this depression the bottom of the loch
apparently rises very gradually towards the eastern end.

The area over 50 feet in depth is estimated at about 230 acres, or
41 per cent, of the entire area of the loch, while the area between the
shore and the 50-feet line is estimated at about 331 acres, or 59 per
cent, of the total extent of the loch.

Loch Doine (see Plate VII.). — Loch Doine has a total length of
nearly one mile, with a maximum width of over a quarter of a mile ;
the mean breadth is about 0'21 mile, or 370 yards, being 21 per cent, of
the length. The total number of soundings taken in Loch Doine was 90,
the average depth of these being 34 1 feet, the greatest depth being
65 feet (11 fathoms). The bulk of water contained in the loch is
estimated at 196,000,000 cubic feet, and the mean depth at 33 feet
(5J fathoms). The length of the loch is 81 times the maximum depth,
and 160 times the mean depth.

THE FRESH-WATER LOCHS OF SCOTLAND. 11

lii Loch Doine the deeper water occupies approximately the centre
of the loch, the deepest soundings (65 feet) being found, however, nearer
the eastern than the western end of the loch. The 50-feet depression
covers over one-third of the area of the loch, being about three-quarters
of a mile in length with a maximum width of over one-eighth of a mile.
It seems doubtful whether this 50-feet depression is not really separated
into a larger and smaller portion, for the narrow neck shown on the
map is founded upon a single sounding of exactly 50 feet. The greatest
depth, 65 feet, was observed in several spots situated towards the
eastern end of the loch. The area with depths over 50 feet is estimated
at 47 acres, or 35 per cent, of the entire area of the loch, while the area
with depths less than 50 feet is estimated at 88 acres, or 65 per cent,
of the area of the loch.

Loch Lubnaig (see Plate VI.). — The outflow from Lochs Doine and
Voil passes by the river Balvag, 5 miles in length, into Loch Lubnaig,
the surface of whose waters is, according to the Ordnance Survey maps,
405 feet above sea-level, or 9 feet lower than that of the other two lochs.
A consideration of the intervening ground indicates that in post-glacial
times these three lochs formed one single sheet of water.

Loch Lubnaig has a total length of nearly 4 miles, following ap-
proximately a line drawn down the centre of the loch, with a maximum
width of about two-fifths of a mile. The mean breadth is nearly a
quarter of a mile, or 422 yards, being 6 per cent, of the length. Its
waters cover an area of about 614 acres (or nearly 1 square mile), and it
drains an area 36J times greater, or about 22,400 acres (nearly 35 square
miles). The total number of soundings taken in Loch Lubnaig was
394, the average depth of these being 20J feet, and the greatest depth
observed 146 feet (24 J fathoms). The bulk of water contained in the
loch is estimated at 1,144,000,000 cubic feet, and the mean depth at
42^ feet (or 7 fathoms), being 29 per cent, of the maximum depth.
The length of the loch is 145 times the maximum depth, and 493 times
the mean depth.

Loch Lubnaig differs from the other lochs in the neighbourhood in
that it does not constitute a single basin. The bottom is apparently
very irregular ; the contour lines of depth do not follow the contour of
the loch, hollows and ridges alternate with each other, and in some
places comparatively deep water is found close to the shore, while in
other places shallow water extends a considerable distance from shore.
The loch is also, comparatively speaking, very narrow and shallow con-
sidering its size, nearly two-thirds of the area being under 50 feet in
depth. The loch may be conveniently divided into two halves, defined
by the central constriction in the outline of the loch at the entrance of
the Ardchullarie burn, where the bottom shallows and separates the two
principal deep depressions; the northern half trends in a north-west

12 BATHYMETRICAL SURVEY OF

and south-east direction, while the southern half trends almost directly
north and south.

There are two depressions in which the depth exceeds 100 feet, with
an isolated sounding of 106 feet between them. The larger depression
is contained in the southern half of the loch, and is over half a mile
in length, with a maximum width of about one-sixth of a mile ; the
greatest depth in this depression is 118 feet. The smaller but deeper
depression is situated at the base of the northern half of the loch,
occupying a central position, and is over a quarter of a mile in length,
with a maximum width of about one-sixth of a mile. The deepest
sounding in the loch (146 feet) is centrally placed in this depression,

FIG. 8. LOCH LUBNAIG, LOOKING NORTH.

(Photograph by G. W. Wilson.)

lying north-westward of the point where the Ardchullarie burn enters
the loch. The area of over 100 feet in depth is estimated at about 55
acres, or 9 per cent, of the entire area of the loch

There are three depressions in which the depth exceeds 50 feet.
The largest is contained in the southern half of the loch, and is over
1J miles in length, with a maximum width of over a quarter of a mile.
The second in point of size is centrally placed, and is over half a mile
in length, with a maximum width of over a quarter of a mile. The
third and smallest (and also the shallowest, the deepest sounding in it
being 62 feet) is situated near the northern end of the loch, and is little
more than a quarter of a mile in length and about one-eighth of a mile

THE FRESH- WATER LOCHS OF SCOTLAND. 13

in greatest width. At the upper end of the loch, where the river
Balvag enters, there is a long spit formed of detritus brought down by
the river, and this end of the loch for a distance of three-quarters of a
mile is very shallow, while at the lower end the 50-feet contour is
found within 200 yards of the outlet. The area between the 50-feet
and 100-feet contours is estimated at about 162 acres, or 26 per cent, of
the total area of the loch, while the area with depths under 50 feet is
estimated at about 397 acres, or 65 per cent, of the area of the loch.

When the loch was visited on April 6, 1899, it appeared from marks
on the shore that the water had lately been 4 feet 10 inches higher than
at that time, and it has been known to have been 12 or 18 inches lower,
so that the rise and fall is about 6 feet in all. On one occasion a disc
was visible down to a depth of 17 ^ feet, and on another down to 20 J feet.

On the western shore, between 1J and 1J miles from the southern
end of the loch, there is a remarkable sandy spit, which stretches out
towards the centre of the loch, the origin of which appears to us some-
what puzzling (see the Geological Notes by Messrs. Peach and Home).

Loch Chun (see Plate VIII.). — There are two lochs in Perthshire bear-
ing this name, the one a little loch in the parish of Blair Atholl. The
Loch Chon now_ under consideration lies to the south of Loch Katrine,
and trends in a north-west and south-east direction. It lies at a height
of 296 feet above sea-level, and the river into which it flows expands, a
little distance to the south-east, into the small loch, Lochan Dubh or
Loch Dhu, the surface of which is 10 feet lower. Loch Chon is over
In miles in length, and the greatest width is about one-third of a mile.
The mean breadth, obtained by dividing the area of the loch by its
length, is a quarter of a mile, being 15 per cent, of the length. Its
waters cover an area of about 277 acres, or less than half a square mile,
and it drains an area about 14i times greater, or nearly 4000 acres
(nearly 6 J square miles) . The number of soundings taken in Loch Chon
was 157, the greatest depth observed being 75 feet. The mass of water
contained in the loch is estimated at 358,000,000 cubic feet, and the
mean depth at over 29 feet, or 39 per cent, of the maximum depth. The
length of the loch is 120 times the maximum depth, and 305 times the
mean depth.

Loch Chon is irregular in outline, and the contour-lines are also
irregular. The deepest part of the loch (i.e. exceeding 50 feet) forms a
long, narrow depression, situated approximately in the centre of the
loch, but closer to the western than to the eastern shore, about seven-
twelfths of a mile in length, with a maximum width of over one-sixth of
a mile. The maximum depth, 75 feet, was found comparatively very
close to the western shore, being in fact only about 130 yards distant;
this gives a slope of almost 1 in 5, and a similar steep slope is indicated
by the near approach to the shore of the contour-lines for a considerable

14

BATHYMETRICAL SURVEY OF

distance along the western side of the loch. The slope from the eastern
shore is, generally speaking, more gradual. The 25-feet depression is
divided into two portions by the rising of the floor of the loch about a
quarter of a mile from the southern end. The maximum depth in the
smaller southern depression is 49 feet. The larger 25-feet depression,
separated from the smaller one by an interval of about one-eighth of a
mile, is over 1J miles in length, approaching close to the north-western
end of the loch, with a maximum breadth of three-eighths of a mile.
This larger depression is very irregular in outline, occupying nearly the
full width of the loch towards the centre, while a short distance farther
south there is a narrow constriction in the vicinity of the Heron islands.

FIG. 9. LOCH CHON.

(Photograph by G. W. Wilson.)

The area of the bottom between the shore line and the 25-feet
contour is about 119 acres, or 43 per cent, of the total area of the loch;
that between the 25- and 50-feet contours is about 127 acres, or 46 per
cent., and that deeper than 50 feet is about 32 acres, or 11 per cent.

Lochan Dubh (see Plate VIII.).— This little basin is one-fifth of a
mile in length, and less than one-sixth of a mile in maximum width.
Its waters cover an area of about 11 J acres, and it drains an area
eighteen times greater, or about 205 acres. The mean breadth is less
than one-tenth of a mile, or 45 per cent, of the length. Twenty-five
soundings were taken in Lochan Dubh, the maximum depth observed
being 41 feet. The cubic mass of water is estimated at 586,000 cubic

THE FRESH-WATER LOCHS OF SCOTLAND.

15

feet, and the mean depth at nearly 21 feet, or 50 per cent, of the
maximum depth. The length of the loch is 28 times the maximum
depth, and 56 times the mean depth.

Lochan Dubh is very simple in construction, shoaling on all sides
down to the deepest part. As in Loch Chon the slope seems to be much
steeper off the western than the eastern shore, a cast of 35 feet having
been taken comparatively very close to the west side. The water
shallows where the loch narrows a little above the outlet, a depth of
3i feet being found where the bottom is covered with reeds. The area
of the bottom between the shore and the 25-feet contour line is about
7 acres, or 60 per cent, of the area of the loch, and that deeper than
25 feet is nearly 5 acres, or 40 per cent.

FIG. 10. LOCH ARD, WITH BEN LOMOND IN THE DISTANCE.

(Photograph by J. Valentine.)

Loch Ard (see Plate IX.). — Loch Ard receives the outflow from
Lochan Dubh and Loch Chon ; it trends in an east and west direction,
sending out one prolongation to the south and another to the east. Its
level is 105 feet above the sea. It is over three miles in extreme length,
including the eastern prolongation, but the body of what may be called
the loch proper is about 2 J miles in length : from the head of the loch
to Helen's rock. The greatest width, measured from the extremity of
the southern prolongation to the northern shore of the loch, is over one
mile, the mean breadth being two-fifths of a mile. Its waters cover an
area of over 600 acres (nearly one square mile), and it drains an area of
more than ten times greater, or about 6250 acres (9J square miles). The

16 BATHYMETRICAL SURVEY OF

number of soundings taken in Loch Ard was 308, the maximum depth
being 107 feet. Thus the deepest part of Loch Ard dips two feet below
sea-level. The cubic mass of water contained in the loch is estimated at
1,150,000,000 cubic feet, and the mean depth at nearly 44 feet, or 41
per cent.- of the maximum depth. The length of the loch is 113 times
the maximum depth, and 277 times the mean depth.

Loch Ard proper forms a comparatively simple basin, shoaling from
the shores down to the deepest part. The 100-feet depression occupies
a central position, and is about three-quarters of a mile in length. The
75-feet depression is over 1^ miles in length, while the principal 50-feet
depression, over 1 \ miles in length, is separated by a very short interval
from a small detached area in the north-western part of the loch at
Kinlochard, in which the depth exceeds 50 feet. The 25-feet contour-
line is very irregular, and there are four isolated patches in which the
depth exceeds 25 feet : the largest one in the southern prolongation at
Couligartan has a maximum depth of 39 feet ; a second small area occurs
between the southern prolongation and the island of Eilean Gorm, in
which the maximum depth is 35 feet ; the other two areas are situated
in the eastern prolongation of the loch, the maximum depth in the
eastmost depression near the outlet of the loch being 33 feet, and in
the other 39 feet. The soundings taken between Duke Murdoch's
castle and Briedach show that the bottom is very irregular : the first
sounding gave a depth of 17 feet, followed by 44 feet, then 38 feet, then
23 feet, then 31 feet, the bottom rising on approaching the elevation on
which Briedach and a beacon are situated.

The area of the bottom between the shore and the 25-feet contour-
line is about 240 acres, or 40 per cent, of the area of the loch; that
between the 25- and 50-feet contours is about 154 acres, or 25 per cent. ;
that between the 50- and 75-feet contours is nearly 64 acres, or 11 per
cent. ; that between the 75- and 100-feet contour-lines is about 78 acres,
or 13 per cent. ; and that deeper than 100 feet is nearly 65 acres, or
11 per cent.

Lake of Menteith (see Plate X.). — The Lake of Menteith resembles
Loch Leven somewhat in outline, and in being relatively a very shallow
basin. It is also historically related with Loch Leven, since Queen Mary
at one time lived within their precincts ; the ruins of the Priory on
Inchmahome, in which she resided before her removal to France, are of
great architectural beauty and antiquarian interest. Its surface is only
55 feet above the sea. Its maximum length is over 1J miles, and the
maximum width over one mile, the mean width being five-eighths of a
mile. Its waters cover an area of 652 acres (over one square mile), and
it drains an area 6-J times greater, or over 4000 acres (nearly 6J square
miles). The number of soundings taken in the Lake of Menteith was
375, the maximum depth being 77 feet. A small portion of the bottom

THE FRESH-WATER LOCHS OF SCOTLAND. 17

thus falls below sea-level, as indicated on Plate X. The cubic mass of
water contained in the loch is estimated at 562,000,000 cubic feet, and
the mean depth at 19| feet, or 26 per cent, of the maximum depth.
The length of the loch is 110 times the maximum depth, and 427 times
the mean depth.

The bottom of the Lake of Menteith is apparently very irregular.
The 10-feet line follows approximately the outline of the loch, except
that it is considerably removed from the south and south-east shores,
where the land is bordered by reeds; it also surrounds the islands of
Inchmahome, on which the Priory is situated, and Inch Talla, on which
the castle is situated. Dog Isle, and a submerged crannog covered by

FIG. 11. LAKE OF MENTEITH.

(Photograph by G. W. Wilson.)

four feet of water in the north-eastern angle of the loch at Port of
Menteith. The area of the bottom covered by more than 25 feet of water
is cut up into three portions. The eastmost of these 25-feet depressions
has a maximum depth of 48 feet ; the central 25-feet depression is almost
triangular in outline, with a maximum depth of 49 feet. The westmost
25-feet depression is the largest and the deepest : it is almost divided
into two halves by a narrow constriction between Inch Talla and Stable
Point, the deepest water observed in the southern half being 49 feet,
while the northern half contains the deepest water found in the loch.
Here the bottom falls below the depth of 50 feet over an area of nearly
32 acres, the 50-feet depression being about a third of a mile in length
and over a sixth of a mile in maximum width. It encloses a small patch

c

18 BATHYMETRICAL SURVEY OF

in which depths of 75, 76, and 77 feet were observed — the maximum
depth of the lake — situated comparatively close to the northern shore
at Coilledon.

The area of the bottom between the shore and the 10-feet line is
about 223 acres, or 34 per cent, of the whole area of the loch; that
between the 10- and 25-feet contours is about 255 acres, or 39 per cent. ;
that between the 25- and 50-feet contours is about 142 acres, or 22 per
cent. ; and that over 50 feet nearly 32 acres, or 5 per cent.

Loch Leven (see Plate XI.). — Loch Leven has long been famous for
its trout. In the old Statistical Account of Scotland* we read :— ' The
high flavour and bright red colour of the trout seem evidently to arise
from the food which Nature has provided for them in the loch. What
appears to contribute most to the redness and rich taste of the Loch
Leven trout is the vast quantity of a small shellfish, red in its colour,
which abounds all over the bottom of the loch, especially among the
aquatic weeds. The trout when caught have often their stomachs full
of them."

About the year 1770 the trout brought about a halfpenny each, large
and small, and perch a halfpenny per dozen. Some years later the price
was doubled, and towards the end of the century the trout were sold at
4d. per lb., pike 2d. per lb., and perch 2d. per dozen. In 1845 two
boats and four boatmen were employed during part of the fishing season,
while in 1891 there were twenty-two boats on the loch for the use of
anglers. Extensive operations for the draining of the loch were com-
pleted about the year 1845 at a cost of £40,000, by which the loch was
lowered 4J feet, and the area reduced by about 1400 acres ; some people
maintain that the quality of the trout has been injuriously affected by
the draining. Prior to 1856 rod fishing was disappointing, but about
that time, from some cause that does not appear to have been satis-
factorily explained, the fish rose more freely to the bait, angling became
more encouraging, and Loch Leven became a resort for anglers from all
parts of the country. Some years ago the fishing was taken over by the
Loch Leven Angling Association, Limited, who pay a rental of £1000
per annum. The statistics regarding the trout caught by rod in the
loch, and their weight, show great fluctuations from season to season.
In 1872 over 17,000 were taken, the average weight being nearly 1 lb. ;
in 1873 the take fell to 13,400, in 1874 to 6400, in 1875 to 5000, and in
1876 even less. In 1877 the take rose again to 6000, in 1878 to 13,000,
and in 1879 to 21,000, but the average weight seems to have been less.
The best year recorded during the last quarter of a century was in 1888,
when 23,516 trout were taken weighing 21,074 Ibs. In 1893, 1898,
1899, and 1900 the takes again exceeded 20,000, but the weight never

* Vol. vii. pp. 166, 168, 1793.

THE FRESH-WATER LOCHS OF SCOTLAND.

19

equalled the 21,000 Ibs. of 1888, the nearest approach being in 1893,
when 23,100 trout, weighing 19,500 Ibs., were caught. Last year (1900)
the trout taken by the rod numbered 23,811, weighing 15,584 Ibs., an
average of 0'654 Ib.

Perch are also abundant, and pike are not uncommon. Formerly
charr were frequently taken, but they appear to have become scarce in
recent years. The American weed (El odea canadensis) appears to have
become firmly established in certain parts of the loch, and is causing a
great deal of trouble, all the means hitherto tried for the purpose of
destroying it being only of temporary benefit.

FIG. 12. LOCH LEVEN AND CASTLE.

(Photograph by J. Valentine.}

On St. Serf's island (which is about 80 acres in extent) are the
remains of a Priory dedicated to St. Serf, said to have been founded by
a Pictish king, and given to the Culdees. The castle (on Castle island,
which has an area of about 5 acres) is said to have been founded by
Congal, son of Dongart, king of the Picts. It is famous in history as
the prison in which the unfortunate Queen Mary was incarcerated for
eleven mouths, and from which she effected her romantic escape.

Considering the area covered by the waters of Loch Leven, it is an
extremely shallow loch. When measured by the Ordnance Survey
officers in August, 1893, its surface was found to be 349'6 feet above the
level of the sea. In form it is somewhat pear-shaped, the greatest
length being 3| miles from south-east to north-west, and the greatest
width is about 2§ miles. The mean width is nearly 1J miles, being 40
per cent, of the length. Its waters cover an area of nearly 3400 acres

20 BATHYMETRICAL SURVEY OF

(5J square miles), and it drains an area nearly ten times greater, or
about 32,500 acres (nearly 51 square miles). The number of soundings
taken in Loch Leven was 538, the maximum depth being 83 feet. The
bulk of water contained in the loch is estimated at 2,195,000,000 cubic
feet, and the mean depth at less than 15 feet, being 18 per cent, of the
maximum depth. The length of the loch is 232 times the maximum
depth, and 1296 times the mean depth.

An examination of the map shows how uneven the bottom of Loch
• Leven is. The deepest part of the loch is cut up into two portions, the
larger depression lying to the west and south of St. Serf's island, with a
maximum depth of 83 feet — the greatest depth observed in the loch — the
smaller depression being situated in the north-western part of the basin,
and attaining a maximum depth of 79 feet. The larger 70-feet depres-
sion lies to the west of St. Serf, with two isolated soundings of 70 feet
farther to the south-east ; the smaller 70-feet depression is in the north-
western part of the loch, with an isolated sounding of 71 feet. The
larger 50-feet depression to the south and west of St. Serf is nearly a
mile in length, while the smaller in the north-western portion of the
basin is a little over half a mile in length. The larger 20-feet depression
is very irregular in outline, extending from near the outlet of the loch at
the river Leven along the southern and western shores of St. Serf, and
sending a wide branch in a westerly direction and another in a north-
westerly direction towards Castle island, with an extreme length of
about two miles. It is separated by an interval of about half a mile (in
which the bottom rises in a pear-shaped elevation — a sunken island —
covered by 5 to 9 feet of water) from the north-western 20-feet depres-
sion, which is apparently extremely regular in outline, being about
two-thirds of a mile in length, and over one-third of a mile in maximum
width. The 10-feet line follows approximately the contour of the loch,
except off the eastern shore to the north of St. Serf, where the 10-feet
line runs on an average nearly three-quarters of a mile distant from the
shore. The 10-feet line also surrounds Reed Bower, Castle island, and
Scart island, and in addition to the elevation in the central part of the
loch already mentioned, there is another small elevation covered by
depths of 3 to 7 feet near the southern shore off Waterbutts plantation.

The area of the bottom between the shore and the 10-feet contour-
line is about 1430 acres, or 42 per cent, of the whole area of the loch ;
that between the 10- and 20-feet contours is nearly 1450 acres, or 43
per cent. ; that between 20 and 50 feet is about 375 acres, or 11 per
cent. ; that between 50 and 70 feet is nearly 110 acres, or 3 per cent. ;
and that over 70 feet is about 25 acres, or 1 per cent. It will thus be
seen that no less than 85 per cent, of the bottom is covered by less than
20 feet of water, and the mean depth as already mentioned is less than
15 feet.

The details regarding the physical features of the different lochs are
collected together in the following table for convenience of reference : —

THE FRESH-WATER LOCHS OF SCOTLAND.

21

Ratio to
area
of loch.

g s

o »O

i— 1 CO

2

•s

•"•0

1

•5 .

$ § 5 8 2

s r

= .= <
= —

111

— it C
oe: . 9 ei

= !*

•8

« f

§J

ll

W<5

B5^|

(1 : =

- i bJI
^^

co op

a- a

a

cccccccc

^ o o o o o

3-8

a -a

1-8

? ? ^ ?

t- (N CC « ^

— 5 01 ^H cc

J I

E^^

s I

S a 8 I

ij

311

1

i s
11

rl
1 1

.

1 3

a

I

22 BATHYMETRICAL SURVEY OF

From the table on previous page it will be seen that in the thirteen
lochs over 3800 soundings were taken, and that the aggregate area of
water-surface is about 17 square miles, so that the average number of
soundings per square mile is 225. The aggregate volume of water
contained in the lochs is estimated at 36,543 millions of cubic feet. The
area drained by these lochs is about 228 square miles, or about 13 times
the area of the lochs.

Deposits. — As a general rule, the materials forming the deposits in
these fresh-water lochs become finer grained the further from the shore
and the deeper the water. Off the mouths of rivers and burns there is
frequently a considerable accumulation of gravel and fine sand, extend-
ing for some distance into the lake and occasionally reaching rather
deep water. Large stones, gravel, and sand are usually found all round
the shores within the limits of wave-action. The height and length of
the waves, and the depth to which wave-action extends, depend on the
size and depth of the loch.

The central parts of the lochs are occupied by a fine impalpable mud,
which is found in its most characteristic form in the greater depths far
from shore ; it is usually of a light or dark brown colour, and sometimes
there are indications of different-coloured layers. The usual mineral
species are quartz, felspars, black and white mica, amphibole, pyroxene,
magnetite, garnets, &c. Chemical analysis showed that these fine muds
contained no appreciable calcareous matter, but traces of sulphuretted
hydrogen were always present. The loss on ignition after drying at
90° C., due to organic matter and combined water, varied from 13 to
26 per cent. Diatoms were observed in nearly all the samples, and
vegetable fibre was usually present in greater or less abundance.

The samples from the deepest part of Loch Ka.trine were brownish,
fine-grained homogeneous muds, with glittering mica-flakes, consisting
principally (50 to 70 per cent.) of angular mineral particles exceeding
0-05 mm. in diameter, the mean diameter being about 0-15 mm., with
clayey and vegetable matter, and many minute mineral particles less
than 0'05 mm. in diameter. A few diatoms were observed, and one
sample, after drying at 90° C., gave 19' 91 per cent, loss on ignition.

The mud from the deepest part of Loch Achray was of a grey-brown
colour, containing much vegetable and clayey matter, the mineral
particles exceeding 0'05 mm. in diameter making up probably 30 or 40
per cent, of the whole deposit. Some fine diatoms were observed, and
the loss on ignition, after drying at 90° C., amounted to 12'84 per cent.

The mud from a depth of 102 feet in Loch Vennachar was yellowish-
brown in colour, containing about 20 per cent, of mineral particles
with a mean diameter of O'l mm., but principally made up of
amorphous clayey matter with vegetable matter, and many minute
mineral particles less than 0'05 mm. in diameter. There were a few

THE FRESH- WATER LOCHS OF SCOTLAND. 23

diatoms; the loss on ignition, after drying at 90° C., amounted to
14 per cent.

The mud from the deeper part of Loch Drunkie was of a dirty brown
colour, containing 10 to 20 per cent, of mineral particles with a mean
diameter of O'l mm., but consisting principally of amorphous clayey
matter, with many small mineral particles, and vegetable matter. A
few diatoms were observed. The loss on ignition, after drying at 90° C.,
amounted to 26'38 per cent.

The deposit from the deeper parts of Loch Arklet was similar to that
from Loch Drunkie, with even a larger quantity of vegetable matter.

The mud from the deeper parts of Lochs Doine and Voil was of a
brown colour, with 30 to 40 per cent, of mineral particles, and clayey
and vegetable matter, and a few diatoms. A sample from a depth of
80 feet in Loch Voil, after drying at 90° C., gave 22'74 per cent, loss on
ignition.

The material from a depth of 136 feet in Loch Lubnaig was a brown
impalpable mud, with 30 to 40 per cent, of mineral particles, much
clayey and vegetable matter, and a few diatoms.. The loss on ignition,
after drying at 90° C., amounted in one sample to 16'29 per cent., and
in another sample to 15-76 per cent.

Three brown muds were examined from Loch Chon, from depths of
10 feet, 14 feet, and 37 feet. The colour was lighter, and the mineral
particles were more abundant and larger, in the shallower water. In
the deposit from 10 feet the mineral particles made up probably 35
to 40 per cent., and included a few rock fragments which sometimes
attained a diameter of 10 mm., the mean diameter of the mineral
particles exceeding O'Oo mm. in diameter being about 0'3 mm., while in
the deposit from 37 feet the percentage falls to about 10, with a mean
diameter of O'l mm. Inversely, clayey matter and vegetable matter
were more abundant in the deeper water, mixed with minute mineral
particles, impregnated with ferric oxide, and containing diatoms,
Sponge spicules, arenaceous Foraminifera, and Entomostracous skeletal
fragments.

A sample from the deepest part of Loch Ard was a dark-grey mud,
consisting principally of vegetable and clayey matter, the mineral
particles not exceeding 10 per cent., with a mean diameter of about
O'l mm. The organic remains observed were the same as in Loch Chon.

A fine-grained dark-brown mud from a depth of 60 feet in Loch
Leven contained probably not more than 5 per cent, of mineral particles
exceeding 0'05 mm. in diameter, the bulk of the deposit consisting of
clayey and vegetable matter, containing many beautiful diatoms, with
Sponge spicules and Entomostracan remains.

Temperature Observations. — During the various visits to the different
lochs, many observations were made on the temperature of the water,

24

Loc
nbna

BATHYMETRICAL SURVEY OF

^ t^* Oi CO CO 00 OO

o

ju ° »0

p co . cp

""3 on CO " " "

O m «..)

_ ^H . O GO

° 4* : : : co : 61

»o »o >o

JO >o >t >t

00 CO G^l (

gs ° 8 ; ; ;s ; 3

.^ cf

-J5^

II

Q

w"

"^i- *P . . .»P . .

3S 10 ' 10

1-5

<N(N..p.Oi ...P.

o^.,,!,!!^!^ :::<N:.

p . p , QO . p . . >p .cp . op p

^ T1^ .^"* . W T* . .** .^pip?5?5^!^ . . .pop

- ^ - . .p
p

^ . "? . •? . *p . . ^p . *p . ^ . *p

0 'ib : : : oo : ^ : : : c^i : : c^i : ^ : ^ : >-H

00 lr^» CO ^O ^ CO CO

o
^r^

Ip _ < __ ip . . »p »p

co : : :^ : :^H :^j

%sl

a a

-H (N CO 1C OO O O

THE FRESH- WATER LOCHS OF SCOTLAND. 25

both on the surface and at intervals below the surface, down to the
bottom. All the serial temperatures taken in Lochs Katrine, Arklet,
Achray, Druiikie, Vennachar, Doine, Voil, and Lubnaig have been
collected together in the table,* and, in order to make the record more
complete, the temperatures taken by Jardine in 1812 and 1814 in Loch
Katrine are given in the first two columns.

Locli Katrine. — The surface temperatures taken in Loch Katrine
during the seven days from June 5 to 11, 1897, are extremely interest-
ing, as illustrating the effect of the wind. The range of temperature
during this time was 12 J°, from 45°"3 to 57°'8, the highest reading being
observed at Trossachs pier on the evening of June 5, and the lowest at
the same place on the evening of June 9. This was evidently the
result of a strong east wind, which commenced to blow on the 6th,
and continued from the same direction till the 9th, blowing the warm
surface water before it from the east towards the west end of the loch,
while colder water from below was drawn up to the surface at the east
end of the loch to take its place. The gradual cooling of the water at
the east end of the loch is well shown by the temperatures taken at
Trossachs pier from day to day : thus at 6.30 p.m. on June 5 the
temperature was 57°'8; at 11.30 a.m. on the 6th it was 56°'2; and at
4 p.m. 55°'3; at^7 a.m. on the 7th it was 49°'2 ; at 10.30 a.m. on the
8th it was 46°'3 ; and at 7.15 p.m. on the 9th it was 45°'3. By 9.30
a.m. on the llth it had again risen to 50°*1. The effect of the wind was
also shown by a series of surface temperatures taken from the steamer
on its way from Stronachlachar pier to the Trossachs pier on the evening
of June 9 : thus at Stronachlachar the temperature was 52°'6; near the
waterworks, 52°'0; near Letter, 49°'6; near Brenachoil, 48°'8 and
48°-0; near Ellen's isle, 47°*4 and 47°'0; and finally at Trossachs pier,
45°'3. It will thus be seen that it is very unsafe to rely on a single
observation at one spot as giving a sure indication of the temperature of
the surface waters of a loch as a whole at any given season. A year later
(from June 4 to 9, 1898) the temperature of the surface waters of Loch
Katrine was not observed to fall below 50°. On November 26, 1897,
the surface temperature varied only from 460<8 to 47°-4, and on April
13 and 15, 1899, from 41°'2 to 42°*7.

The serial temperatures in Loch Katrine are shown graphically
in the accompanying curves (Fig. 13), which exhibit the march of tem-
perature in the waters of the loch throughout the year. The curve for
April shows that the water from top to bottom has a temperature rang-
ing between 41° and 42° Fahr. In the two curves for June the heating
effect of the sun on the surface layers is indicated, but in depths beyond

* Temperature observations in the surface waters of some of the lochs under considera-
tion have been taken by Mr. Thomas Scott, and the results published in the Annual Reports
of the Fishery Board Jor Scotland.

26 BATHYMETRICAL SURVEY OF

•

20 fathoms the temperature has not been appreciably affected. In June,
1898, the whole body of water in the loch was apparently slightly
warmer than in the previous June. The November curve shows a great
accumulation of summer heat in the layers down to depths of 30 and 35
fathoms. By this time cooling has set in, and progresses slowly until
the spring, when the whole of the layers assume the nearly uniform
temperature indicated by the April curve. The temperature of the
bottom of the loch in depths of 400 feet may vary one or two degrees
from year to year, this variation being due to the strength of the winds
and general character of the climate in different years.* The highest

56

o
55

5*
53-

o

52

c
51-

4-8-

Temperature of LOCH KATRINE

i i
1

APRIL 1899

JUNE 1897

JUNE 1898

.NOVEMBER 1897

3 5 10 15 2O 25 30 35 4-O 45 5O 55 6O 65 7O 75 80 82/£

TAT H O M S

PIG. 13. CURVES OF TEMPERATURE IN LOCH KATRINE.

temperature recorded in Loch Katrine is 58°-4, so that the range in the
central parts of the loch throughout the whole year is probably about
18° Fahr.

* See Murray, " Some Observations on the Temperature of the Water of the Scottish
Fresh-water Lochs" (Scottish Geographical Magazine, vol. xiii. p. 1, 1897). At noon on
March 10, 1900, in calm and frosty weather, the temperature of the surface water of
Loch Katrine, over the deepest part of the loch, was 40°-3, at 10 feet 40°-2; at all other
depths down to 492 feet the temperature-readings were 40°-0 and 40° 1. On the same
date the readings in shallow water were 39° -4.

THE FRESH-WATER LOCHS OF SCOTLAND. 27

Loch Arklet. — Temperature observations taken in the centre of Loch
Arklet on June 11, 1897, gave a temperature at the surface of 55°-4,
and at 5 fathoms 54°-4 ; on April 13, 1899, the surface temperature was
42°' 7. Temperatures as high as 61° have been recorded in this loch,
so that the annual range probably exceeds 29°.

LochAchray. — Observations taken in June and November, 1897, and
April, 1899, showed that the temperature of the surface waters varied
from 41° in April to 59°-5 in June, the temperature in November being
46°. An intermediate observation at 5 fathoms in the centre on June
12, 1897, gave 53°'5. The highest reading recorded at the surface of
this loch is 640<1, so that the annual range probably exceeds 32°.

Loch Drunkie. — Observations taken on June 12, 1897, showed that
the surface waters had a temperature of 57°, and an intermediate
observation at 5 fathoms gave 52°'6. On April 14, 1899, the surface
temperature was 42°"4.

Loch Vennachar. — The temperature observations taken in June, July,
and November, 1897, and April, 1899, showed that the temperature of
the surface water varied from 41° in April to 56°*5 in June, the tem-
perature in November being 46° to 47°, while the water of Blairgarry
stream had a temperature of 42°-2. Serial observations in the centre
of the loch on June 10, 1897, showed a gradual fall in the temperature
from 55°-8 at the surface to 47°-2 at 15 fathoms; while on April 11,
1899, the temperature was practically uniform from surface to bottom
at 42°-5 to 42°-7.

Loch Doine. — Observations taken on July 7, 1897, and April 10, 1899,
showed that the temperature varied from 42° in April to 54° in July.
Serial observations in the centre of the loch in July gave a temperature
at the surface of 54°, falling to 52°-l at 10 fathoms, while in April the
temperature was found to be nearly uniform from surface to bottom,
ranging from 41°-8 to 42°'6.

Loch Voil. — Observations taken in July, 1897, and April, 1899, showed
that the temperature of the surface water varied from 41°-2 in April to
56°-5 in July. Serial observations taken on July 7, 1897, showed that
in the centre of the loch the temperature at the surface was 55°-0, at
5 fathoms 54°-0, and at 16 fathoms 54°*5, while further down the loch
the temperature appeared to be rather higher, viz., 56°'0 at the surface,
and 55°-3 at 3 fathoms and 8 fathoms. Serials taken on April 10, 1899,
showed that the whole body of water was practically uniform in tem-
perature at about 42°.

For the sake of comparison, a few surface temperatures were taken
at the head of Loch Earn on July 6, 1897, the temperature of the loch
varying from 480>8 to 49°'2, while that of the streams flowing into the
loch was 52°-2. On the following day (July 7, 1897) the surface of Loch
Voil near the shore had a temperature of 560>4, and a little distance

28 BATHYMETRICAL SURVEY OF

from the shore 54°- 6, while the water of the burn flowing into the loch
had a temperature of 53°- 6, and higher up the stream 53°'l. It thus
appears that the waters of Loch Voil were warmer than those of Loch
Earn, and in the case of Loch Voil the stream feeding the loch had a
lower temperature than the loch itself, while in the case of Loch Earn
the streams were warmer than the waters of the loch.

Loch Lubnaig. — Observations were taken in Loch Lubnaig only on
April 6 and 8, 1899, and showed that at that time the temperature of the
water was nearly uniform from surface to bottom, the range being only
from 41°-8 to 42°'7.

From the point of view of temperature, the Scottish fresh-water lochs
may be divided into those which freeze during hard winters, and those
which never freeze. Those which freeze over in winter are shallow
lochs, and when frozen the water-temperature beneath the ice is at the
maximum density point of fresh water (39°-l) or lower. In spring the
temperature of these shallow lochs rises much more quickly through
the heat of the sun, and the whole mass of water attains a higher
temperature than in the case of the deeper lochs; they also lose their
heat much more quickly in the autumn than the deep lochs, and con-
sequently have a much wider range of annual temperature. In the deep
lochs — those with 400 or more feet of depth — the temperature of the
water never rises so high in summer, nor sinks so low in winter, as
in the shallow lochs, and the range is much less. The temperature of
the bottom water in some cases does not change more than 1° Fahr.
from year to year, and in the deepest lochs it appears to be practically
constant at all times and seasons; 40° is the lowest temperature that
has been recorded at the bottom in any of these deep Scottish lochs, so
that the maximum density point is never reached. In summer, autumn,
and even early winter, it is possible, by observing the temperature of
the surface and sub-surface waters, to form a fairly accurate idea of the
depth of a loch, the temperature being higher the shallower the loch.
The waters from a deep loch — like Loch Katrine — are much the best for
the water-supply to a city, for in summer the temperature is relatively
low and in winter it is relatively high.

The serial temperature observations taken in Lochs Chon, Ard,
Menteith, and Leven are given in the following table, but many tem-
perature observations were taken at the surface, which are not, of
course, included in the table : —

[SERIAL TEMPERATURE OBSERVATIONS.

THE FRESH-WATER LOCHS OF SCOTLAND.

29

Depth

Loch
Chon.

Lochan
Dubh.

Loch Ard.

Lake of
Menteith.

Loch Leven.

in
Feet.

May 15,

1900.

May 15,

1900.

Aug. 6,
1899.

May 16,
1900.

May 14,
1900.

June 11,
1900.

June 22,
1900.

Sept. 1,
1900.

o

o

o

0

0

o

0

0

0

51-8

547

63-0

51-7

51-3

587

62-3

58O

5

,

...

...

58-4

62-2

6

507

51-1

61-3

51-4

5M

...

...

10

...

...

58-0

62-1

12

61-3

50:5

...

.

18

>t

61-3

48-5

..

...

,

20

49-5

...

507

57-5

24

61 !2

48-3

...

30

60-5

477

...

57-4

61 5

35

...

47-6

...

...

...

.

40

48-6

_

50-5

56-6

48

50-1

47-1

...

.

.

50

_

56-5

59-3

57-3

60

48:5

48:2

46:9

50:2

56-3

56-8

56-6

70

..

...

...

56-2

56-6

76

__

...

...

...

90

..

47-5

46-5

...

...

96

...

47-5

46-5 *

...

...

..<

100

••

...

46-4

...

...

...

Loch Chon and Lochan Dubh. — These lochs were sounded on the 15th
May, 1900, when the surface temperature in Loch Chon varied between
51°-8 and 54°-5 ; below the surface the temperature decreased gradually
down to 48°-5 at 60 feet, so that the range observed throughout the
whole body of water was only about 6°. In Lochan Dubh the surface
temperature was slightly higher than in Loch Chon (54°-7), while the
temperature of the deeper water was observed to be about 1° lower
(470> 6), so that in the small body of water contained in Lochan Dubh
the range was greater than in the larger Loch Chon, viz., 7°.

Loch Ard. — Loch Ard was visited on the 5th and 6th August, 1899,
and again on the 16th May, 1900. The highest surface temperature
(64°- 6) was observed in the southern prolongation of the loch in August,
the maximum temperature observed at the same time in the body of the
loch proper being 63°. It will be seen that the whole body of water
was warmer in August, and that a drop of 10° was recorded between the
depths of 30 and 50 feet, the extreme range of temperature from surface
to bottom being 17°. No steep gradient was observed in May, the
temperature decreasing gradually from top to bottom, the extreme
range observed in May being 8°-7.

Lake of Menteith. — The Lake of Menteith was visited on the 7th
August, 1899, and the 14th May, 1900. No serials were taken in
August, when the surface temperature varied only from 62°'2 to 63°'2.
In May the surface temperature varied from 51°*1 to 52°'2, and the
temperature decreased gradually from surface to bottom, the range
observed in May throughout the whole body of water being only 2° —

30 BATHYMETRICAL SURVEY OF

from 50°'2 to 52°-2 ; the extreme range shown by all the observations
amounts to 13°.

Loch Leven. — Loch Leven* was sounded on the llth, 12th, and 22nd
June, 1900, and again on the 1st September and the 23rd October. A
reading at the surface on the llth June at 5 p.m. gave 580>7, and on
the 12th June at 4.50 p.m. a temperature of 67°'5 was observed — a
range of nearly 9° in one day. This reading of 67°'5 may be specially
referred to as being, so far as we are aware, the highest temperature
hitherto recorded in the waters of Scottish lochs, the next highest
reading being one of 65° observed by Mr. Scott at the surface of Loch
Oich in August, 1897. In September the surface temperature ranged
only from 57° to 58°-5. We are doubtful as to the working of the
thermometer made use of in the October visit, and the readings have
therefore not been included in the table.

The serials taken in June indicate the rapidity with which the waters
of a shallow lake like Loch Leven become heated up in summer. During
the eleven days between June llth and 22nd the whole body of water
had acquired a higher temperature, amounting to about 4° in the upper
layers down to 30 feet, to nearly 3° at 50 feet, and to half a degree at
60 feet. But, while the body of water in a shallow lake absorbs heat
more rapidly than that in a deep lake, it also loses heat more rapidly,
and therefore the quantity of heat stored up in the waters of a deep
lake may not be less than that stored up in the waters of a shallow lake,
as Delebecquef seems to think. From a preliminary study of our tem-
perature observations in the Scottish lochs we believe the reverse to be
the case. For instance, Loch Katrine and Loch Leven are comparable
as regards superficial area, but Loch Katrine is six times as deep as Loch
Leven, and contains twelve times as much water; if the temperature of
the water in the two lochs were taken simultaneously before and after a
definite interval in summer, it seems probable that, while the tempera-
ture in Loch Leven might have been raised much higher than in Loch
Katrine, the amount of heat stored up, as represented by the number of
cubic feet raised 1°, would be found to be greater in Loch Katrine than
in Loch Leven, and that the difference would bear some relation to the
ratio between the bulk of water and the area of surface exposed to the
rays of the sun. We shall endeavour to work this matter out in greater
detail as our temperature observations accumulate, and we may return
to the subject in a later paper.

Biology. — Tow-net and other observations show that the nature and

* We understand that the temperature of the water of Loch Leven has been taken at the
pier once a day (at 12 noon) during the five months of the fishing season for the past twenty-
five years, but we have had no opportunity of examining the observations.

f " La quantite* totale de chaleur emmagasin£e dans un lac variera d'autant moins que
ce volume sera plus grand par rapport a cette surface " (Les Lacsjranqais, p. 150).

THE FRESH- WATER LOCHS OF SCOTLAND. 31

amount of the organic life in the fresh-water lochs are subject to great
variation in the different lochs when compared with each other, and in
the same loch at different seasons of the year. Large numbers of
observations are being collected, and we may look for interesting results
when these are in a state for discussion. Generally speaking, the
pelagic fauna and flora are much more abundant in the warm summer
months than at other times of the year, and are also more abundant in
the shallow lochs than in the deep ones. In the spring months there is
a great development of diatoms and other Phytoplankton, which render
the water less transparent than at other times of the year.

Mr. Thomas Scott has lately been comparing the fauna in several of
the Scottish lochs at different seasons of the year ; some of his results
for the lochs now under consideration may be noted.

In Loch Katrine the Entomostraca and other invertebrates were
scarcer than in the other lochs examined. Fourteen species are recorded,
Bosmina longispina being the only species present in all the gatherings ;
Leptodora was entirely absent from the gatherings collected during the
colder months. Cyclops strenuus and Polyphemus appeared to be more
frequent in the upper part of the loch, and Bosmina and Leptodora in
the lower part. The sides of Loch Katrine do not generally present
conditions very favourable to shore-dwellers, and an examination of the
shore about Stronachlachar yielded scarcely anything that differed from
the tow-net captures, while at the lower end the shore between the
Trossachs pier and Ellen's isle yielded much better results. Here forty
species of Crustacea were obtained, as well as one or two species of
Mollusca, but they were all individually scarce. The Cladocera were
more numerous in species in the warmer than in the colder months,
while with the Copepoda the reverse was observed, though the difference
was not so great.*

In Loch Arklet, Holopedium gibberum, one of the most remarkable
species of the Cladocera in Britain, was moderately common in the
tow-net gatherings collected in September and November, 1897, and in
June, 1898, it was abundant all through the water, but when the loch
was visited in March, 1898, not a trace of Holopedium could be seen.
In June, when Holopedium was so abundant, other species previously
observed were either very scarce or absent, as if they had been more
or less crowded out by this particular cladoceran. Eleven crustacean
species are recorded, Daplinia being the only form obtained in all the
gatherings ; Bythotreplies was observed in September and June, but not
in November and March, and Leptodora occurred only in September.
Infusoria (Ceratium, &c.) and micro-algae were much less frequent in
June than in the other gatherings. Forty-two species of Entomostraca
were obtained by hand-net round the shores of Loch Arklet, including

* Scott, Seventeenth Annual Report of the Fishery Board Jor Scotland, pt iii. pp. 148-151, 1899.

32 BATYHMETRICAL SURVEY OF

a few comparatively rare forms; very few molluscs were observed in
any of the gatherings.*"

Twelve species of Entomostraca were captured by the tow-nets in
Loch Achray, Diaptomus, Daphnia, and Bosmina being taken in all the
gatherings. Holopedium, though common in September and June, was
not observed in November and March ; Bythotre plies also appears to
be subject to somewhat similar seasonal variation. Fifty species of
Entomostraca and four species of Mollusca were obtained by the
hand-net, and by dragging the tow-net for a short distance over the
bottom of Loch Achray. Three rare species : Diaptomus wierzejskii,
Lathonura rectirostris, and Monospilus dispar were obtained, and in
June a green fresh-water sponge (Spongilla fluviatilis) appeared to be
moderately common in some shallow parts of the loch.f

Loch Vennachar contains a rich crustacean fauna, as well as other
invertebrates, most of which are suitable for fish food. Of forty-five
species of Crustacea recorded from Lochs Katrine, Achray, and Venna-
char, thirty-five species were observed in Loch Vennachar ; thirteen of
the species from Loch Vennachar were not observed in either Lochs
Katrine or Achray; fifteen of the species were common to the three
lochs. I

Twenty-five species of Crustacea and four species of Mollusca are
recorded from Loch Lubnaig, including a new cladoceran (Alona
neglecta), and one or two species new to Britain. §

The following results were obtained by Mr. Scott in Loch Leven in
1890, 1897, and 1898. ||

In June, 1890, Mr. Scott found the fauna to be abundant and varied
— Mollusca, Arthropoda, Annelida, and Protozoa being more or less
common all over the loch. Mollusca were common and generally dis-
tributed, except at that part of the loch called the " Shallows," the
bottom of which consists of little else than fine sand, and is therefore
not so suitable as a habitat for these organisms as where the bottom
consists of mud or vegetable debris. Fourteen species of Mollusca were
obtained, comprising five Lamellibranchs and nine Gasteropods. The
more common forms were Sphcerium corneum, Pisidium fontinale,
Valvatapiscinalis, and Planorbis cotitortus. The swan-mussel (Anodonta
cygncea) appeared also to be frequent.

The Crustacea were by far the most numerous and varied of the
invertebrate fauna of the loch. Cladocera and Copepoda occurred
in great profusion all over and through the water. Daphnice, were

* Scott, Seventeenth Report of the Fishery Board for Scotland, pt. iii. pp. 143-146.
t/6W.,PP. 153-156.

J Scott, Fourteenth Report of the Fishery Board for Scotland, pt. iii. p. 167, 1895.
§ Scott, Thirteenth Report of the Fishery Board for Scotland, pt. iii. p. 247, 1894.
|| See Ninth and Seventeenth Annual Reports of the Fishery Board for Scotland, part iii.,
1890 and 1899.

THE FRESH- WATER LOCHS OF SCOTLAND. 33

most abundant. Cyclops, especially 6'. strenuus, was also. plentiful.
Ostracoda were not so common in the loch itself as they were around its
margin, particularly those parts that were more or less overgrown
with vegetation, as round the north-east shore. Seventeen species of
Ostracoda were obtained along this part of the shore; twelve species
were obtained from the south shore, and only eight from the loch itself.
Among the Cladocera the rare and interesting Leptodora Jiyalina
occurred in considerable numbers; Monospilus tenuirostris was also
frequent in tjie material collected at one or two places. The following
were the common species: — Gammarus pulex, Diaptomus gracilis,
Cypria sertna, C. ophthalmica, Limnicythere sancti-patrici, Daphnia
lacustris, Phurorus triynntUu8y Cliydorus sphcericus.

The larvae of insects were abundant in the loch, especially the larvae
of the Iphemeridae. The Libellulidae and Phryganidae were also repre-
sented in the larval stage more or less frequently. Some idea may be
formed of the myriads of these organisms present in the loch when it is
stated that a conspicuous ridge composed of cast-off skins of insect larvae,
which had been washed ashore during the preceding stormy weather,
extended along the margin of the loch for a considerable distance. The
curious so-called " water-bears " (Tardigrada), now included in the
class Arachnida, were common among the decaying vegetable matter at
the bottom. Species of Notonectidae or " water-bugs," and of aquatic
Coleoptera were also more or less common, though their distribution
seemed to be more localised.

The worms were represented by several species — parasitic and non-
parasitic. Among the former were Schistoceplialus solid us, obtained
from the body -cavity of a Stickleback (Gasterosteus aculeatus), and a
species of tape-worm (Bothriocephalus latus?), several of which were
found in the alimentary canal of the trout, six specimens being taken
from one fish. The heads of the parasites were fixed at the extreme
end of the cceca or blind tubes of the stomach, and their bodies were
so elongated as to extend well down into the intestine. Uusally one
parasite occupied a ccecum. Tubifex rivulorum was very common in the
loch.

Rhizopoda were common all over the loch. Several forms were
obtained in the dredged and hand-netted material; the more typical
varieties observed were: — Difflugia pyriformis, D. globularis (much
less frequent than the first named), D. corona (appeared scarce), D.
marsupiformis (of frequent occurrence). Diatomacea were abundant,
especially in the deeper parts of the loch, and included a considerable
number of species.

Mr. Scott visited Loch Leven again in September and December,
1897, and in March and June, 1898, when he found that the free-
swimming Entomostraca, though very abundant, consisted mainly of
the one species, Daphnia lacustris. Leptodora hyalina was moderately

34 BATHYMETRICAL SURVEY OF

common in the September gathering, but was not observed in any of
the other three. Diaptomus gracilis was frequent in the gathering
collected in December, but was scarce in the others. Bythotrephes
longimanus, though present in both the September and June gatherings,
was not observed in those collected in December and March. Cyclops
strenuus, though present in all the gatherings, was scarce.

A few male Daphnice were observed in the December gathering, but
in none of the others ; females with pseudova were frequent in all the
gatherings. When the loch was examined in June, 1890, both Daphnella
brachyura and Polyphemus pediculus were observed in the tow-net
gatherings, but neither of these species was obtained in any of the
gatherings recently collected. Infusoria and micro-algae, which were
moderately frequent on the first three occasions when the loch was
examined, were quite abundant in the loch in June, but these minute
forms did not appear to be generally diffused, apparently occurring in
shoals, and being particularly plentiful to the south of Reed Bower.

The examination of the shore yielded a much greater number of
species than were captured by the tow-nets, but individuals were not
nearly so numerous. Fifty-five species of Crustacea were obtained in
the shore gatherings collected during the recent experiments. The
records of species obtained when the loch was examined in 1890 include
a few that were not observed in the recent gatherings (viz., Cypria
ersculpta, Candona lactea, Ilyocypris triplicate, Bosmina longirostris,
B. longispina), and if these and the species captured with the tow-nets
be added, they increase the number of crustacean species to sixty-five ;
it is quite probable that even this number will yet be added to when the
loch comes to be more thoroughly examined. Only five species were
observed in all the gatherings in 1890, 1897, and 1898, viz., Caniho-
camptus staphylinus , C. minutus, Cypria ophthalmica, Candona
Candida, Chydorus sphcericus. The species recently captured include
one Amphipod (Gammarus pulex), and eighteen each of Copepoda,
Ostracoda, and Cladocera. The largest number of species of Crustacea
obtained in any of the recent shore gatherings from Loch Leven was
in that collected on 13th June. This gathering yielded thirty-nine
species, or only four less than the total number observed in the tow-net
and hand-net gatherings collected in June, 1890.

The Cladocera, as a whole, were scarcer in those gatherings collected
in the colder months than in the others. It may also be stated that in
March the level of the water was much higher than during any of the
other visits, and this no doubt accounted, partly at least, for the great
scarcity of Cladocera in the gathering collected at that time; the
reduced temperature incidental to the season may also have had some
influence in bringing about this result.

Rainfall and Outflow. — An attempt has been made to arrive at an

THE FRESH-WATER LOCHS OF SCOTLAND.

35

approximation to the total amount of rain falling annually on the
drainage areas of the lochs draining into the river Teith, although the
available records are far from sufficient for the purpose. Dr. Alexander
Buchan, F.R.S., has kindly supplied us with information regarding the
readings of the rain-gauges at observing stations within, and in the
vicinity of, the catchment-basins of these lochs. The positions of these
rainfall stations, and the mean annual rainfall, are shown on one of the
accompanying maps (see Plate III.), and further particulars will be
found in the following table : —

Station.

Height of
rain-gauge
above
sea-level.

Years observed.

Mean annual
rainfall in
inches.

Feet.

Ardlui

50

1865-70

115-10

Firkin

100

1866-79

98-38

Arrochar

15

1864-98

81-31

Head of Duchray ...

1800

1854-98

84-27

Glengyle

380

1854-98

92-25

Top of hill, Loch Katrine tunnel

830

1861-98

77-95

Brig o' Turk

270

1854-98

64-47

Loch Drunkie

420

1861-98

63-62

Loch Vennachar ...

275

1861-98

57-31

Between Ben Ledi and Glen Finlas

1800

1854-98

53-68

The Gart .. ..

230

1872-98

54-47

Leny

345

1861-98

54-23

Blaircreach .

460

1893-98

82-63

Stronvar

422

1860-98

75-49

Lochearnhead

320

1866-84

65-50

Tyndrum

792

1858 61, 72-3, 76-7

99-10

Grouping these stations and their mean annual rainfall into those
likely to represent the rainfall on the catchment-basin flowing out of
Loch Vennachar, and those representing the rainfall on the catchment-
basin flowing out of Loch Lubnaig, we arrive at an average rainfall of
76-25 inches for the Loch Lubnaig catchment, the mean height of the
rain-gauges being 538 feet above the level of the sea, and an average
rainfall of 75*37 inches for the Loch Vennachar catchment, the mean
height of the gauges being 528 feet.

The entire catchment-basin flowing out of Loch Vennachar (i.e. the
combined drainage-areas of Lochs Katrine, Achray, Drunkie, and Ven-
nachar) is about 75-29 square miles, and the mean height calculated
from the bulk of laud above the level of the lochs is about 704-185 feet ;
the mean height of the surfaces of these fotir lochs above sea-level is
33 H feet, so that the mean height above the sea of the entire catchment
is about 1035-685 feet. The entire catchment-basin flowing out of Loch
Lubnaig (i.e. the combined drainage-areas of Lochs Voil, Doine, and
Lubnaig) is about 73*39 square miles, and the mean height above the
level of the lochs is about 935-129 feet ; the mean height of the surfaces

36 BATHYMETRICAL SURVEY OF

of these lochs above sea-level is 412 feet, so that the mean height above
the sea of the entire catchment is about 1347-129 feet.

The usual practice among engineers is to add 2J per cent, of rainfall
for each 100 feet of height above rain-gauges. Applying this rule to
the Loch Vennachar catchment-basin, where we have an observed rain-
fall of 75-37 inches at an average height of 528 feet, we must add 12-7
per cent, for the additional 508 feet of mean height, making an
average annual rainfall over the entire catchment of 84-94 inches.
This would give an annual fall of rain on the entire catchment equal
to 14,857,214,000 cubic feet. Applying this rule, in like manner, to
the Loch Lubnaig catchment-basin, where we have an observed rain-
fall of 76-25 inches at an average height of 538 feet, we must add 20
per cent, for the additional 809 feet of mean height, making an
average annual rainfall over the entire catchment of 91-5 inches. This
would give an annual fall of rain on the entire catchment equal to
15,600,760,000 cubic feet.

There is another method of estimating the rainfall, without taking
the mean height of the drainage-area into consideration. Supposing the
usually accepted increase of 2J per cent, per 100 feet of height, and also
the mean annual rainfall at the average height of the rain-gauges, to be
approximately correct, it is possible to calculate the rainfall at any given
height. For the Loch Vennachar catchment the probable rainfall at
the same heights and intervals as the contour-lines on the Ordnance
Survey maps has been calculated from the starting-point of the mean of
the observing stations 75-37 inches at 528 feet. Thus at the surface of
Loch Vennachar the rainfall would be about 70*5 inches ; at 500 feet
above the sea, 75-2; at 750 feet, 79-9; at 1000 feet, 84-6 inches; and
so on, adding 6J per cent, for each succeeding interval of 250 feet.
Multiplying the area between any two consecutive contour-lines by
the mean of the two figures calculated for the same two lines should
give an approximation to the amount of rain falling on that area. The
result as obtained by this method for the entire catchment-basin flowing
out of Loch Vennachar is given in the following table : —

Cubic feet.

Level of lochs to 500 feet, 16-53 square miles x 72'8 inches = 2,795,710,000

500,, 750 „ 10-67 „ x 77 '5 „ =1,921,117,000

750 ,,1000 „ 10-35 ., x 82-2 ,, =1,976,514,000

1000 ,,1250 „ 9-46 ,, x 86 '9 ,, =1,909,847,000

1250 ,,1500 „ 10-22 „ x 91 '6 ,, =2,174,874,000

1500 ,,1750 „ 7-86 „ x 96 -3 ,, = 1,758,47<>,<KX)

1750, ,2000 ,, 5-94 ,, x 101 -0 „ =1,393,784,000

2000, ,2250 ,, 3-06 „ x 1057 ,, 751,422,000

2250, ,2500 ,, 0-99 „ x 110-4 ,, 253,917,000

Over 2500 ,, 0"21 ,, x 115-1 ,, 56,154,000

Total 14,991,815,000

This result comes very near to that obtained from the calculation

THE FRESH-WATER LOCHS OF SCOTLAND. 37

based upon the mean height, which gave a total annual rainfall of
14,857,124,000 cubic feet.

Applying the same method to the entire catchment-basin flowing
out of Loch Lubnaig, we arrive at the following result : —

Cubic feet.

Levels of lochs to 500 feet, 6 '82 square miles x 74 '6 inches = 1,181,982,000

500,, 750 „ 7-15 „ x 77-9 „ =1,293,991,000

750,, 1000 „ 9-05 ,, x 82-7 „ =1,738,769,000

1000,, 1250 ,, 970 „ x 87-4 „ = 1,969,568,000

1-250,, 1500 „ 9-89 „ x 92-2 „ =2,118,434,000

1500 ,,1750 „ 9-43 „ x 97 O „ =2,125,060,000

17.50,, 2000 „ 8-06 „ x 1017 ,, =1,904,337,000

2000 ,,2250 „ 6-64 „ x 106'5 „ =1,642,879,000

•J-J50,, 2500 „ 3-30 „ x 111-3 „ = 879,148,000

2500,, 2750 ,, 1-88 „ x 116'1 „ = 507,081,000

•_>7.->0 „ 3000 „ 1-02 „ x 120-8 „ = 286,256,000

Over 3000 ,, 0-35 x 126 '6 = 102,941,000

Total 15,750,446,000

Here, again, there is a close agreement between the result obtained
by this method and that calculated from the mean height, which gave
a total annual rainfall of 15,600,760,000 cubic feet.

A third method of estimating the amount of rain falling on any
particular region is afforded by drawing lines of equal rainfall, measur-
ing the areas between the lines, and multiplying by the mean annual
rainfall. Where the lines are based upon sufficiently numerous records
of rainfall at various heights, this method should give excellent results ;
but in the cases under discussion the number of observing stations is
small, and the majority of the rain-gauges are situated on the low-lying
grounds, only two being placed at heights exceeding 1000 feet, both
at 1800 feet : therefore the figures obtained in these cases are most
probably below the truth. Nevertheless, we have attempted to lay
down the lines of equal rainfall from the available records, as shown
on the accompanying rainfall map (see Plate III.). The areas enclosed
by the lines of rainfall have been measured with the planimeter, and
the rainfall calculated for the Loch Vennachar catchment-basin, with
the following results : —

Cubic feet,

50 to 60 inches, 12 '35 square miles x 55 inches = 1,578,040 000
60 „ 70 „ 28-97 „ x 65 „ = 4,374,714,000

70 „ 80 „ 18-93 „ x 75 „ = 3,298 372,000

80 ,, 90 „ 8-55 „ x 85 „ = 1,688,400,000

90 ,, 100 ., 4"21 , x 95 „ = 929,166,000

100 „ 110 ., 2-28 ,, x 105 „ = 556,175,000

Total 12,424,867000

In like manner, the rainfall has been calculated for the Loch
Lubnaig catchment-basin, with the following results : —

38 BATHYMETRICAL SURVEY OF

50 to 60 inches,
60 ,, 70 ,,
70 „ 80 ,,
80 „ 90 „
90 „ 100 „
100 „ 110 ,,

Total 12,737,328,000

The results obtained by these three methods may be summarized

Vennachar catchment. Lubuaig catchment.

First method ... 14,857,214,000 15,600,760,000

Second „ ... 14,991,815,000 15,750,446,000

Third „ ... 12,424,867,000 12,737,328,000

Cubic feet.

3-79 square miles

x 55

inches = 484,272,000

23-89

x 65

,, =3,607,591,000

21 79

x 75

,, = 3,796,700,000

19-02

x 85

,, = 3,755,928,000

441

x 95

,, = 973,307,000

0-49

x 105

,, 119,530,000

Mean ... 14,091,299,000 c. ft. 14,696,178,000 c. ft.

Since Loch Katrine has been made use of by the Glasgow Corpora-
tion as the source of the water-supply to that city, a record has been
kept of the amount of water flowing out of Loch Vennachar — or rather,
a record has been taken twice a day of the depth of water flowing over
a weir at Coilantogle, from which the quantity of water discharged may
be calculated. When the height of the water on the weir exceeded 5
inches, the weir became a drowned weir, so that it was difficult to
estimate the outflow, as there was a considerable velocity of approach,
especially during floods.

Mr. Gale has kindly supplied us with the readings, taken twice a
day during the year 1869, of the depth of the outflowing water at
Coilantogle, and from these figures the outflow has been estimated for
that year at 9,572,000,000 cubic feet. The year 1869 was the driest
year during a period of twenty-four years, and we are not satisfied that
this computation can be accepted as a very correct estimate of the out-
flow from this catchment-basin even for that year. It would have been
interesting to have calculated the outflow for twenty-five years in the
same way as we have done for the year 1869, and to have taken the
mean. However, accepting the above estimate for the year 1869, and
adding to it the quantity of water supplied to Glasgow for that year,
which, from Mr. Gale's table showing the average amount of water
supplied per day during the first six months of the years 1866 and 1871,
may be taken at about 1,659,300,000 cubic feet, we find that the mean
rainfall exceeds the outflow in this year by

According to the first method 3,625,914,000 cubic feet.

second „ 3,760,515,000

third „ 1,193,567,000

Or a mean of 2,859,999,000 ,,

Leslie* made experiments for twenty consecutive years on the

* See Jour. Scot. Met. Soc., vol. v. p. 108, 3878.

THE FRESH- WATER LOCHS OF SCOTLAND. 39

allowance to be made for absorption by vegetation and for loss by
evaporation, and he calculated that the average annual amount of water
absorbed and evaporated is equal to about 13 inches of rainfall. On
this basis, and assuming for the present that the evaporation from the
surface of the water is equal to absorption and evaporation from the
land, the total amount of water lost through absorption and evaporation
over the entire catchment-basin of Loch Vennachar would be about
2,273,885,000 cubic feet per annum.* Comparing this figure with the
figures given above showing the excess of rainfall over outflow, we
observe that, according to the mean of the three methods, the difference
between the rainfall and outflow is greater than would be accounted for
by absorption and evaporation as estimated by Leslie, there being an
excess according to the first two methods, and a deficiency according to
the third method.

The foregoing figures, calculated for the year 1869, show that the
rainfall unaccounted for by outflow at Coilantogle, and supply of water
to Glasgow, is according to the first method 26 per cent., according to
the second method 27 per cent., and according to the third method
8 per cent. : this percentage must be referred to loss by absorption,
evaporation, and the loss of water through underground channels.

NOTES ON THE GEOLOGY OF THE LOCH KATRINE DISTRICT.

By Messrs. BEN. N. PEACH, F.R.S., and JOHN HORNE, F.G.S., from
unpublished observations made during the course of the Geological
Survey of Scotland. With Geological Map (Plate II.). Published
by permission of Sir Archibald Geikie, D.C.L., F.R.S., Director-
General of the Geological Survey of the United Kingdom.

The lochs in this district to be first treated of, with the exception of
Loch Arklet, lie within the catchment-basin of the river Teith above
Callander. Though situated about a mile to the west of Loch Katrine,
the small lake, Loch Arklet, drains into Loch Lomond.

1. Geological Structure of the area embracing these Lochs.

All the lochs, save the lower part of Loch Vennachar, lie within the
territory of the crystalline schists of the Highlands, which are bounded
along the Highland border by a powerful fault stretching from Stone-
haven to the Firth of Clyde. As shown on the geological sketch-map,
this dislocation extends from Aberfoil north-east by Leny to Luirgeann
on the Kelty water. On the south-east side of this fault the strata

* The evaporation from the surface of the lakes will, of course, exceed Leslie's figures
for loss through absorption and evaporation.

40 BATHYMETRICAL SURVEY OF

belong to the lower Old Red Sandstone formation, comprising, next the
fault, andesitic lavas and agglomerates well seen in the Kelty water.
Further to the south-east there is a broad belt of conglomerate arranged
in beds, which are inverted or vertical near the fault, and as the
observer approaches the plain they dip towards the south-east and
pass underneath the overlying red sandstones.

On the north-west side of this great boundary fault of the High-
lands there is a narrow strip of sedimentary rocks about half a mile in
breadth, referred provisionally to the Arenig division of the Silurian
system, and consisting of red and black shales, radiolarian cherts, lime-
stones, and grits.

To the north of this belt of doubtful strata, the whole of the area
included in the geological map accompanying this paper is occupied by
rocks grouped under the general term of the crystalline schists of the
Highlands. The latter are arranged in a definite order, but as yet it
is uncertain whether it indicates the original sequence of deposition.
The groups are here given in apparent descending order —

7. Garnetiferous mica-schists.

6. Loch Tay limestone with sills of epidiorite.

5. Mica-schists with sills of epidiorite.

4. Schistose epidotic grits (" Green Beds ").

3. Ben Ledi grits, massive and sometimes schistose.

2. Aberfoil slates with subordinate bands of grit.

1. Leny and Aberfoil grit.

For a distance of about 5 miles northwards from the great boundary
fault, the members of groups 1 to 4 are arranged in more or less parallel
belts or strips running south-west and north-east, the strata dipping
at high angles to the north-west. The groups appear in consecutive
order, the Leny and Aberfoil grit being exposed immediately to the
north of the doubtful Arenig rocks, while the Aberfoil slates and Ben
Ledi grits appear successively to the north. The schistose epidotic
grits (group 4), which lie apparently at the top of the Ben Ledi grits,
are developed still further to the north, being traceable from a point
not far to the south of Ben Lomond, north-east by Loch Chon and the
lower part of Loch Katrine, thence across the hills to Strathyre and
Loch Voil. From the Braes of Balquhidder they can be followed north-
wards to Glen Dochart, and they reappear in Glen Falloch in the
extreme north-west part of the map. At the head of Loch Lubnaig
and in the Braes of Balquhidder sills or intrusive sheets of epidiorite
occur at no great distance from the " Green Beds."

In the belt between Loch Chon and Loch Lubnaig the " Green
Beds," together with the Ben Ledi grits, form a series of compound
synclinal folds, the strata being inclined at high angles. To the north
and west of the " Green Beds " the representatives of the Ben Ledi

THE FRESH- WATER LOCHS OF SCOTLAND. 41

grits reappear and cover a wide area, extending from Ben Lomond
north-east by Loch Katrine and the heights surrounding the head of
Loch Voil, northwards by Ben More and westwards to Glen Falloch.
Throughout this extensive area the strata are inclined at gentle angles :
in marked contrast with the structure along the Highland border
already indicated. There is here a change, over part of the area at
least, in the lithological characters of the Ben Ledi grit group. The
strata become more schistose and micaceous, merging in places into
mica-schists. The accompanying geological map shows generally where
these grits still retain their massive character and where they merge
into mica-schists.

The outcrop of the Loch Tay limestone is indicated on the geological
map, from which it will be seen that this limestone, together with the
sills of epidiorite, is traceable from the upper part of Strathyre, by the
Kirkton glen, to Luib, in Glen Dochart.

In addition to the great boundary fault already referred to,
separating the lower Old Red Sandstone from the crystalline schists,
various faults trending N.N.E. and S.S.W. traverse the south-east
part of the area under consideration. These are, in the main, branches
of the great dislocation which has been traced across the Highlands
for a distance of 60 miles, from Loch Vennachar by Loch Lubnaig and
Loch Tay to Gflen Tilt. In common with the dislocation referred to,
the branch faults have a down-throw to the west or north-west, and
they shift for some distance the outcrops of the strata which they
traverse. They are truncated by the great boundary fault of the
Highlands, and may be of pre-Old-Red-Sandstone age.

The existing valley-system of the basin of the Teith has been carved
out of a table-land of crystalline schists of varying hardness. Though
there is conclusive evidence of great erosion during the successive
glaciations of the region, yet it is clear that the present valley-system
must have been developed in pre-glacial time. There is one point
connected with the geological structure of this region which has had an
important bearing on the evolution of the valley-system. Along the
Highland border, as already indicated, there is a great development of
conglomerates, coarse pebbly grits, and greywackes, belonging partly
to the crystalline schists and partly to the Old Red Sandstone. These
strata, being vertical or nearly so, would be much less easily eroded
than the gently inclined schistose rocks lying to the north-west. Such
an arrangement would naturally lead to the formation of narrow and
comparatively flat-bottomed valleys behind rocky gorges, the latter
being cut through the vertical beds of hard grit and conglomerate
along the Highland border. That this remarkable structure must have
likewise contributed to the erosion of rock-basins during the glacial
period will become apparent on a closer examination of the geological
structure of the area traversed by the larger lakes.

42 BATHYMETRICAL SURVEY OF

In the case of Loch Katrine, which is the largest and deepest of the
lochs under consideration, there is a great rocky barrier at its outlet due
to the Ben Ledi grits. Here they form a belt over a mile in breadth,
and give rise to the rugged scenery so characteristic of that region.
They appear on the crags of the Trossachs at the mouth of the loch, on
the crest and slopes of Ben Venue (2393 feet), 011 Ben Bhreac (2295 feet),
and on the heights round Ben An (1326 feet). The strike of these hard
and durable strata is E.N.E. and W.S.W. — that is, at right angles to
the outlet of the loch, and the beds are vertical or highly inclined.

The potency of the Ben Ledi grits as a rocky barrier must have been
considerably increased by the development of epidotic grits or " Green
Beds " lying immediately to the north. The latter, though not so
massive as the Ben Ledi grits, are hard and durable ; they are repeated
by a series of compound folds for nearly a mile across the strike, their
northern limit being near Brenachoil Lodge. Their trend is likewise
north-east and south-west, and the beds are vertical or highly inclined.

On both sides of Loch Katrine above Brenachoil Lodge the geological
structure is widely different, for in this area the Ben Ledi grits, grey-
wackes, and slates reappear in a highly schistose form, the strata
dipping generally at low angles to the south-east. Over much of this
region, as already indicated, the altered sediments merge into mica-
schists owing to the development of mica. It is obvious that these
materials would yield more readily to the agents of denudation than
the massive pebbly grits of Ben Venue and the Trossachs.

Loch Achray, which lies about a mile to the east of the outlet of
Loch Katrine, is only about 88 feet below the level of the latter loch.
A powerful fault or dislocation, trending north-east and south-west,
crosses the head of the loch near the Trossachs Hotel, which brings the
massive Ben Ledi grits to the west in contact with slates to the east.
It is a true rock basin which has been excavated mainly in the group
of less durable slates.

Loch Vennachar is crossed by the great boundary fault, already
referred to, along the Highland border, the floor of the eastern portion
being composed of Old Red Sandstone conglomerate, while that of the
western part is formed of grits and slates belonging to the crystalline
schists. Though there is a covering of drift on both sides of the lower
part of the loch, still this sheet of water forms a true rock basin, for the
Old Red conglomerate is exposed in the river about 1200 yards below
the outlet.

Loch Drunkie presents several interesting geological features. On
referring to the map it will be seen that an arm of this loch runs nearly
east and west for upwards of half a mile ; the northern margin is com-
posed of massive grits, while the southern margin and probably the floor
of this branch of the loch is formed of less durable slates. Another
arm of this lake runs N.N.E., in the direction of Loch Vemiachar, the

THK KKKSH-WATER LOCHS OF SCOTLAND. 43

eastern margin of which nearly coincides with the course of a fault that
crosses Loch Vennachar to the east of Lanrick.

The three lakes, Loch Doine, Loch Voil, and Loch Lubnaig, must
have formed one continuous sheet of water in post-glacial time. Loch
Doine is now separated from Loch Voil by two cones of alluvium, to be
referred to presently. Loch Voil is separated from Loch Lubnaig by a
narrow plain of alluvium 5 miles in length, the surface of Loch Lubnaig
being 9 feet lower than that of Loch Voil. These lochs form isolated
parts of a true rock basin. Below the outlet of Loch Lubnaig there is
a prominent rocky barrier composed of the massive grit of Leny and
Aberfoil, from half to three-quarters of a mile in breadth. The strike
of this pebbly grit is north-east and south-west, and the beds are
inclined to the north-west at high angles.

Loch Lubnaig is traversed by several faults, to which special reference
will be made in the sequel. The lower part of the loch coincides with
the trend of two faults, which, in all likelihood, determined for some

distance the course of the river in remote geological time.

•

2. Glaciation.

The glacial phenomena in the lake district of the basin of the Teith
prove beyond doubt that, during the climax of the ice-age, the ice-shed
lay to the north of the area now under consideration; that the ice-
movement was more or less independent of the existing valley-system ;
and that even the highest mountains were over-ridden by the ice. This
great development was followed by a period of local glaciation, when
the glaciers were confined mainly to the existing valleys, and when
the boulder-clay or ground-moraine of the earlier period was largely
removed. The upper limit of the valley glaciation is frequently defined
by prominent lines of moraines strewn with boulders, which rise to a
considerable height on the mountain-slopes. The evidence pointing to
these conclusions may now be briefly summarized.

On the watershed to the north of Lochs Doine and Voil, the trend
of the ice-movement during the great glaciation, as proved by the striae,
was S.S.E. Again, on the lofty watershed east of Loch Lubnaig and
south of Loch Earn, between Ben Each (2660 feet) and Ben Vorlich
(3224 feet), there is conclusive evidence that the highest mountains in
that part of the lake district were overridden by the ice. There the
mountains are composed of grits, and the striae are well preserved. On
Ben Each the striae point S.E. ; on the col between that hill and Stuc a
Chroin, S. 40° E. ; on the latter mountain about S.E., and on the slopes
of Ben Vorlich, at a height of 2500 feet, the trend of the ice-markings is
E. 40° S. In the tract between Loch Lubnaig and Loch Katrine similar
evidence is obtained of a south-easterly movement at great elevations.
For example, on Ben Vane (2685 feet), at a height of 2642 feet, the

44 BATHYMETRICAL SURVEY OF

striae point S. 15° to 20° E. ; on the north and west slopes of Ben Ledi,
S. 35° E., and on the crest of that mountain, at a height of 2875 feet,
the direction is S.E. In like manner the mountains guarding the outlet
of Loch Katrine are glaciated to the summit. Striae occur on the top of
Ben Venue at a height of 2386 feet, pointing S. 40° E. ; on Ben An, at
an elevation of 1750 feet, E. 30° S. ; and on Ben Bhreac, to the west
of Ben Venue, the direction of the ice-markings is S. 30° to 40° E.
Again, on the watershed between Loch Voil and Loch Katrine, the
evidence indicates a south-easterly movement during the great extension
of the ice. For instance, at various points on Taobh na Coille, at
elevations between 2000 and 2250 feet, the striae point S. 30° E., and
on Meall Gaothach, S. 30° E. In the tract immediately to the south-
west of Loch Katrine the trend of the ice-markings varies from S.S.E.
to E.S.E. For example, on Maol Mor (2249 feet) about the 2000-feet
contour-line, to the north of Loch Arklet, the direction is about
S. 15° E. ; and on the crest of Ben Uaimhe, to the south of that loch,
S. 10° to 15° E. Eastwards, throughout the tract between Loch Chon
and the Trossachs, the trend is E.S.E. To the south of the lofty
heights stretching from Ben Venue towards Ben Ledi, the direction of
the striae is more easterly, thus showing that the ice, after crossing the
high ground, was deflected more towards the east (see glacial striae on
Plate II.).

The general south-easterly movement of the ice during the great
glaciation, throughout the lake district of the basin of the Teith, is
confirmed by the dispersal of stones in the boulder-clay, and by the
transport of erratics. Many of the boulders have been carried far from
their source, and are now found on the tops of the highest mountains of
the district, some even at greater elevations than the parent rock.

To the east of Loch Lubnaig, on Ben Vorlich, at a height of 3000
feet boulders of garnetiferous mica-schist are found resting on glaciated
surfaces of pebbly grit. Again, on the same mountain, at a similar
elevation, there are erratics of epidiorite and hornblende schist — rocks
which are associated with the Loch Tay limestone, and which must have
been transported from lower ground to the north. Similar boulders are
met with on Stuc a Chroin and on Ben Each. Again, in the boulder-
clay on the slopes of Ben Ledi, blocks of hornblende schist occur,
which must have been transported for some distance. On the south side
of Loch Katrine, between Stronachlachar and the aqueduct of the
Glasgow waterworks, boulders of quartzite and garnetiferous mica-
schist, which are foreign to the basin of Loch Katrine, are found in the
boulder-clay. Eastwards near Brenachoil Lodge, on the north side of
Loch Katrine, there are blocks of black schist, like that which accom-
panies the quartzite of central Perthshire, and which has not been
detected within the catchment-basin of Loch Katrine. These examples
are sufficient to prove that, during the climax of the glacial period,

THE FRESH -WATER LOCHS OF SCOTLAND. 45

the ice-movement was independent of the existing valley-system.
Indeed, from the evidence furnished by the striae and the transport of
boulders, it may be inferred that the minimum thickness of the ice-
sheet during this period must have been not less than 3000 feet in the
lake district of Perthshire.

The boulder-clay or ground-moraine, which was laid down during
the great glaciation, must have been extensive, for it is found at great
elevations, and it sometimes attains a great thickness. For instance, in
the lee of the ridge of Ben Vane, to the west of Loch Lubnaig, it
reaches a height of 2290 feet, and in places it is over 100 feet thick.
But a large part of this deposit was removed during the later glaciation
by the valley glaciers, for the relics occur above the limits of the valley-
moraines, the latter resting frequently on the solid rock.

Only a brief allusion is necessary to show the development of the
later glaciers. The striae produced by this later movement coincide
generally with the trend of the existing valleys. But though this is
true, there is evidence to prove that even the larger valley-glaciers were
thick enough to overflow minor watersheds. For instance, the glacier
which descended the basin of Loch Katrine was thick enough to override
the low col between that loch and Loch Chon, while another branch
passed westwards by Loch Arklet towards Loch Lomond. Another
example of the same phenomenon might be quoted. The glacier which
descended the basin of Loch Voil towards Loch Lubnaig was thick
enough to overflow the col between Strathyre and Loch Earn, while
another branch ascended Glen Buckie and joined the Loch Lubnaig
glacier at Laggaii.

Moraines are well developed in most of the valleys, and are fre-
quently arranged in concentric lines, as in Glen Finglas, north of Brig
o' Turk. On the south side of Loch Katrine, between the jetty and
Glasahoile, the moraines are distributed in parallel lines along the
shore of the lake. As already indicated, the upper margins of the
valley-glaciers are defined by the moraines.

3. The Soundings viewed in Relation to the Geological History of the
Area, and with reference to the Origin of the Lakes.

Loch Doine, Loch Voil, and Loch Lubnaig. — Reference has already
been made to the fact that, in post-glacial time, Loch Doine, Loch Voil,
and Loch Lubnaig must have formed one continuous sheet of water,
and that their subsequent isolation has been due to the deposition of
sediment.

Loch Doine has been separated from Loch Voil by alluvial cones
laid down by two streams, one from the north at Monachylemore, and
another from the south at Monachyle Tuarach. The 50-feet subaqueous
line has been traced round the Loch Doine basin, and the deepest sound-

46 BATHYMETRICAL SURVEY OF

ing is 65 feet. At the head of this loch there is an alluvial flat that
stretches westwards for 1J miles, formed by the Lochlarig river and its
tributaries. The gradual silting up, which is in constant progress at
the head of Loch Doine at the mouths of the Lochlarig river and Allt
Carnaig, is well shown by the resultant curve in the 50-feet contour-line.

That Loch Voil is merely a continuation of the Loch Doine basin is
further proved by the soundings, for immediately to the east of the
cones just referred to, the 50-feet contour-line is met with, and has been
traced round both sides of the loch eastwards to about Ledereich — a
distance of about 2 miles. From this point eastwards the lake gradually
shallows towards the alluvial flat at Balquhidder, where moraines occur
within 400 yards of Kirkton and Stronvar Bridge. The deepest part of
the lake is enclosed by the 90 -feet contour-line at the head of the loch
near Monachylebeg, and the deepest sounding within this line is 98 feet.

The trend of Lochs Doine and Voil roughly coincides with the strike
of the crystalline schists in that district. It is oblique — indeed, nearly
at right angles — to the movement of the great ice-sheet during the
climax of glacial conditions, and it harmonizes with the course of
the later valley-glacier. Several small faults occur on the Braes of
Balquhidder, north of Loch Voil, and on the hill-slope south of Loch
Doine, but these are of little structural importance.

The long stretch of alluvium that separates Loch Voil from Loch
Lubnaig has been laid down by the Calair burn in Glen Buckie, by the
Kirkton burn at Balquhidder, and by various streams on both sides of
Strathyre. The silting up now in progress at the head of Loch Lubnaig
is well shown by the tongues of alluvium, on both sides of the Balvag
river, that project for some distance into the loch and isolate small
basins of fresh water. About half a mile north of Loch Lubnaig a
moraine rises out of the alluvium, probably a fragment of the adjacent
moraine on both sides of the valley. As the top of this moraine probably
rose above the level of the ancient united lake, the depth of the latter
near this locality could not have been very great.

A glance at the chart of Loch Lubnaig will show that its floor is
much more irregular than that of Loch Voil. This may be accounted
for partly by the presence of alluvial cones formed by various streams,
and by features connected with the geological structure of the basin.

The deepest parts of this lake form two basins enclosed by the
100-feet contour-line, one to the north and the other to the south of
Ardchullarie More. The upper one, about 500 yards long, is 146 feet
deep, and the lower one, about 900 yards long, is 108 feet in depth.
Though now separated by alluvial detritus brought down by the Ard-
chullarie burn from the north-east, and by the Dubh Shruith burn from
the south-west, these basins were probably originally continuous. The
powerful Loch Tay fault with a N.N.E. and S.S.W. course, and with a
downthrow to the west, crosses Loch Lubnaig immediately to the south

THE FRESH- WATER LOCHS OF SCOTLAND. 47

of Ardchullarie More, and strikes the west margin of the lake near
the spit of sand to be referred to presently (see Plate II.). The steep
gradient on the west side of the lake to the north and south of this spit
of sand coincides with the course of the Loch Tay fault. About a quarter
of a mile to the west of the Loch Tay fault a minor dislocation, with a
similar trend and downthrow, crosses the lake and follows the channel
of the Dubh Shruith burn. Now the lower deep basin lies to the east
or upthrow side of the Loch Tay fault, and the upper deep basin is
on the west or downthrow side of the Dubh Shruith fault. These dis-
locations doubtless produced brecciation of the strata along the lines of
movement, which led to more rapid disintegration of the materials.

Close to the north-west limit of the upper basin enclosed by the
100-feet contour-line the loch shallows to 20 feet, and from thence
north-westwards to a point opposite Bienacreag the depth increases to
62 feet. Here there is a small basin enclosed by the 50-feet contour-
line.

At the lower end of the loch, on the east side, there is a steep
gradient which coincides with a line of fault, having a downthrow to
the west (see Plate II.). As already indicated, this dislocation together
with the Loch Tay fault may have determined in part the course of the
river in remote geological time. But an impartial consideration of the
evidence furnished by the soundings shows that the faults cannot
account for the erosion of the lake basin. The striking fact that the
lower deep basin of Loch Lubnaig coincides with the upthrow side of the
Loch Tay fault — the most powerful dislocation traversing the crystalline
schists of this area — shows that this rock-basin must be ascribed to an
erosive agent acting independently of the lines of fault. It has further
been shown that Lochs Voil and Doine must have been originally con-
tinuous with Loch Lubnaig. The deepest sounding in Loch Voil is
98 feet, and in Loch Lubnaig 146 feet, and it is obvious that their
erosion must be ascribed to a common cause. The upper part of Loch
Lubnaig coincides roughly with the trend of the ice-sheet during the
great glaciation, which, from the evidence adduced in the foregoing
pages, must have attained a minimum thickness of 3000 feet. But the
basin must have undergone further erosion by the large valley-glacier.

About half a mile to the south of Ardchullarie More, on the west
margin of Loch Lubnaig, there is a prominent spit of sand extending
into the lake for about 100 yards. It occurs not far to the south of the
bend in the lake, at the meeting-point of the waves produced by the
prevalent westerly winds. By the action of the waves the sand is
steadily borne outwards on both sides of the spit, and from the soundings
it is clear that this feature projects far into the lake. Further, it must
have been in process of formation when the loch stood at a higher level,
for a section appears in the adjacent railway cutting, which shows the
sloping layers of sand coinciding with the form of the spit.

48 BATHYMETRICAL SURVEY OF

Loch Lubnaig originally extended to a point below Coireachrombie,
about three-quarters of a mile below its present outlet. This point has
been silted up by the detritus laid down by the Stank and Anie burns.
The original southern termination of the lake touched the rocky barrier
formed by the Leny grit. It is worthy of note also, that the level of
Loch Lubnaig has been lowered about 20 feet by the denuding action of
the river Leny.

Loch Katrine. — For a distance of 4 miles, west from Brenachoil Lodge
to Stronachlachar — about the half of the total length of the loch — this
lake has a comparatively flat bottom, enclosed by the 400-feet contour-
line. The deepest sounding in Loch Katrine, 495 feet, is at the eastern
limit of this basin, nearly due south of Brenachoil. The chart shows
that the soundings throughout this basin gradually increase in depth
eastwards to Brenachoil Lodge. The position of the deepest sounding
is of interest, seeing that the strata which form the floor of the lake at
this point consist of schistose micaceous grits, to the north-west of the
epidotic grits (" Green Beds ") and the Ben Ledi grits, the two latter
groups having formed the great rocky barrier at and above the outlet of
the lake.

Near the upper end of the loch a rocky barrier crosses the lake from
Portnellan by the Black island to Rudha Maoil Mhir an-t Salainn. The
deepest sounding along this barrier is 90 feet, and the shallowest is 48
feet. On its lower side the 100-feet contour-line well-nigh crosses the
lake. Above it there is another basin over half a mile in length, the
greatest depth of which is 128 feet, immediately in front of the rocky
ridge just referred to. Westwards the lake shallows, and at its head
it has been silted up for a distance of half a mile by the alluvium laid
down by the Gyle river.

Below Brenachoil Lodge the soundings show an uneven floor, due
probably to ridges of rock rather than to morainic deposits, if we may
judge from the geological features on both sides of the lake. Ellen's
isle is composed of epidotic grits (" Green Beds "), and the promon-
tories of Am Priosan partly of ' ' Green Beds ' ' and partly of Ben Ledi
grits. The promontory between the pier and the sluice is formed of
Ben Ledi grits.

During the geological survey of that region several small faults were
found to cross Loch Katrine, but these are of minor importance, and
have produced locally a slight brecciation of the strata. It is a typical
example of a rock basin. The deepest sounding occurs in the front of
the great rocky barrier in the lower part of the lake, in accordance with
what we might naturally expect on the theory of glacial erosion.
Though the soundings prove the deepest part of the lake to be 131 feet
below sea-level, yet this depth is in proportion to the vast thickness of
the ice during the successive glaciations of the basin.

Loch Achray. — This lake forms one basin, the deepest part being

THE FRESH-WATER LOCHS OF SCOTLAND. 49

enclosed by the 90-feet contour-line, and the deepest sounding being
97 feet. A fault, with a downthrow to the west, crosses the head of
the loch at the Trossachs Hotel, which has produced considerable
brecciatioii of the strata, a feature probably continued along the floor
of the loch between the hotel and Achray. The greater part of this
lake is on the upthrow side of the fault just referred to, and the basin,
as already indicated, has been excavated mainly in slates.

Loch Vennacliar. — Between Loch Achray and Loch Vennachar there
is a strip of alluvium, the difference in level between the two lakes
being 6 feet. The successive terraces show that these two lakes
originally formed one sheet of water, which stood at a somewhat
higher level. Loch Vennachar contains one prominent basin, about
2 miles in length, enclosed by the 50-feet contour-line. Within this
limit there are two smaller basins, which fall below the level of the
100-feet contour-line (see Plate V.). The deepest sounding is 111 feet,
which occurs to the north-east of Invertrossachs, on the line of the great
boundary fault along the Highland border, which has a downthrow
to the south-east. West of this dislocation the floor of the lake rises
sharply to a level of 20 feet below the surface. Westwards, however,
near Lanrick, the depth increases to 50 feet, a feature which coincides
with the course of two faults crossing the loch — branches of the Loch
Tay fault, ancl each having a similar downthrow to the west. Doubtless
where the deep soundings coincide with lines of fault, the strata have
been much shattered and crushed, which has led to the more rapid
disintegration of the materials. But though these faults may have led
to local modifications of the floor of the lake, they obviously do not
account for the excavation of the basin. The long, narrow hollow,
crossing obliquely these lines of dislocation, points to glacial erosion.

Loch Drunkie. — Reference has already been made to the geological
features of this basin (see p. 42). In the western portion of the west
branch, where the hollow has been scooped out of slates, a small part
of the floor is enclosed within the 50-feet contour-line. The deepest
sounding, 97 feet, occurs in the north branch of the lake in front of a
ridge to the east, which rises to a height of about 150 feet above the
loch. The direction of the striae at Loch Drunkie is E. 20° S., and
the deepest sounding is found where the erosion must have been
greatest.

Loch Arklet. — This lake lies across the path of the great ice-sheet,
and coincides with the trend of the later movement (see pp. 44 and
45). Both the north and south shores of this loch are surrounded by
moraines, but though such is the case the stream flows over solid rock,
where it leaves the alluvial flat 1J miles west of the outlet, and con-
tinues to flow for half a mile over solid rock. Originally the lake must
have extended westwards to this barrier, for the intervening strip cf
alluvium has been laid down by the burns joining the Arklet water not

E

50 BATHYMETRICAL SURVEY OF

far from the outlet. On this flat there are moraines rising up in the
midst of the alluvium. The greatest depth of the loch is 67 feet. At
the upper or east end, where the loch is shallow, two islets appear, one
formed of solid rock and the other of moraine matter.

The soundings of the various lakes in the basin of the Teith above
Callander, when viewed in connection with the geological structure
and glacial phenomena of that area, furnish strong evidence in support
of the theory of their excavation by ice-action. It is probable that,
though the lakes lie, as a rule, across the path of the great mer de glace,
they may have been partially eroded by that ice-sheet; at the same
time there can be little doubt that their final modification must have
been produced by the large valley-glaciers.

The other lochs surveyed may be briefly characterised as follows : —

Loch Chon. — Loch Chon is a striking example of a rock basin. The
upper portion of the lake is floored by mica-schists, and the lower
portion by the Ben Ledi grits and schistose epidotic grits (" Green
Beds "), the members of the two latter groups being repeated by sharp
folds. The trend of the loch — N.N.W. and S.S.E. — is oblique to the
strike of the strata. At the head of the lake there is a broad alluvial
flat, where it has been silted up for a distance of one-third of a mile by
the detritus laid down by the adjacent streams. In the northern part
of the basin the deepest soundings vary from 33 to 37 feet; but at a
point about half a mile below the present head of the lake the depth
increases from 40 to upwards of 60 feet. This feature coincides with &
line of fault that crosses the loch in a north-east and south-west
direction, its downthrow being to the south-east. From this point
southwards for half a mile there is a narrow basin enclosed within
the 50-feet contour-line, and within this basin there is a narrow trough,
about 100 yards long and upwards of 75 feet deep, near the west
margin of the lake. There is ground for the belief that nearly the whole
of the basin bounded by the 50-feet contour-line is floored by mica-
schist.

About a mile below the head of the lake the soundings prove a
remarkable decrease in the depth, the 25 -feet contour-line near the
Heron islands being deflected towards the centre of the loch. The
shallowing of the basin here takes place along the outcrop of very
massive epidotic grits (" Green Beds "), several glaciated rocky islands
appearing along this line. Southwards to the mouth of the lake there
are alternations of Ben Ledi grits and schistose epidotic grits, the
narrowest parts of the lake coinciding with the exposures of the latter
group.

About 100 yards below the outlet of the lake a prominent band of
schistose epidotic grits occurs, which evidently formed a rocky barrier
during the glaciation of that region. Beyond this outcrop there is a

THE FRESH- WATER LOCHS OF SCOTLAND. 51

small shallow basin, about 41 feet deep (Lochan Dubh), floored by
schistose grits, which is traversed by a fault trending north-east and
south-west, with a downthrow to the east. Across the mouth of this
basin a band of massive, pebbly grits of the Ben Ledi type has been
traced.

A reference to the geological map will show that the direction of the
ice-flow during the great glaciation coincides generally with the trend
of the loch, striae being found on the rocky islands as well as round the
margin of the lake. The evidence supplied by the soundings tends to
support the theory that the basin-shaped hollow has been eroded by
ice-action. The dislocations referred to above have doubtless produced
local modifications of the floor of Loch Chon and of that of the small
basin (Lochan Dubh), but they do not account for the excavation of the
basin.

Loch Ard, — Loch Ard is also a true rock basin, which lies along the
outcrop of a belt of slates between two bands of grit, the deepest part
of the loch, as proved by the soundings, coinciding with the outcrop of
the slates.

From the Mill of Chon downwards to the head of the lake there is
a small alluvial flat pointing to the former extension of the loch in that
direction. At the upper end the soundings show that the average depth
is 25 feet, with the exception of one small depression opposite Ledard
burn, reaching 57 feet in depth. Eastwards, where the loch becomes
narrower, the depth increases. The basin enclosed by the 50-feet
contour-line is 1J miles long, while that surrounded by the 100-feet
contour-line is three-quarters of a mile in length, the deepest sounding
being 107 feet.

The dislocation, with a downthrow to the east, that crosses the loch
in line with Allt-na-Sgeith in a north-east and south-west direction has
not produced any local modification of the floor of the lake, if we may
judge by the soundings. The 100-feet basin crosses this fault without
any apparent increase in depth on the side of the downthrow, which is
probably due to the fact that the dislocation brings slates into contact
with slates. The band of massive grit which forms for a long distance
the southern margin of the loch evidently acted as a barrier during the
period of glacial erosion. Crossing the lake at Briedach, this band of
grit forms the promontory south-east of Glashart.

On referring to the geological map, it will be seen that the band of
grit just described is followed southwards by slates, the outcrop of
which coincides with an expansion of the loch at its outlet, the deepest
sounding being 52 feet. About 600 yards to the east of the outlet the
trend of the latter belt of slates is E.N.E., and here occurs another
small basin upwards of 30 feet in depth.

No ice-markings have been found round the margin of the loch or
near it ; but about half a mile to the south of the upper end of the lake

02 BATHYMETRICAL SURVEY OF

the direction of the striae is E. 20° S., which coincides generally with the
long axis of the loch. Reference has already been made to the more
easterly movement of the ice as it left the mountainous region and
approached the low-lying districts; the course of Loch Ard coincides
with this easterly trend of the ice.

From the evidence adduced it is obvious that the geological structure
of the basin of Loch Ard has had an important influence in the develop-
ment of its present features, the latter being adequately explained by
the theory of glacial erosion.

The Lake of Menteith lies in various superficial deposits, composed
partly of boulder-clay and stratified beds of the 100-feet beach. It is
within the area occupied by the Old Red Sandstone, and the solid rock
is visible only at one locality, at Coilledon. Loch Leven likewise lies in
superficial deposits.

THE FRESH-WATER LOCHS OF SCOTLAND.

53

LOCHS OF THE TAY BASIN.

E 'tent of the Tay Basin. — The whole area of the drainage basin of
the Tay, including the estuary as far as a line joining Tents Muir Point
with Monifieth, as measured with the planimeter on the 1-inch Ordnance
Survey maps, is 2509*73 square miles.* Considerably more than one-
fourth of this area drains directly into fresh-water lochs, of which there

30 £ng Milt

FIG. 14. INDEX MAP OF THE TAT BASIN.

are seventy, including some of the largest in Scotland — Lochs Tay and
Ericht, for instance, being over 14 miles in length, while eight of them
exceed 2 miles in length.

* Geikie (An Elementary Geography of the British Islands, London, 1888, p. 86) gives the
drainage basin of the Tay as 2250 square miles and Lawson (The Geography of River Systems,
London, N.D., p. 6) as 2400 [square] miles. According to Geikie, the Tay pours a larger
volume of water into the sea than any other British river, and its drainage area is the largest
in Scotland, and seventh in point of size in the British Islands, being exceeded by that of
the Shannon in Ireland, the Thames, Severn, Ouse, Trent, and Great Ouse in England.

54 BATHYMETRICAL SURVEY OF

The river-systems, which arise in the most mountainous and
magnificent regions of Scotland, may be divided into four principal
branches, viz., the Garry branch (the most northerly), the Tummel
branch, the Tay branch, and the Earn branch (the most southerly). .

(1) The Garry branch rises on the flanks of Beinn Mholach, Beinn
Bhoidheach, and Carn Beag an Laoigh, flowing by various streams
into Loch Garry, thence by the river Garry into the river Tummel at
Faskally, to the north-west of Pitlochry, receiving the waters of the
Erochy at Struaii, and those of the Tilt at Blair Atholl.

(2) The Tummel branch rises in the Black Mount, the westernmost
of the sources of the Tay river-systems, flowing by the river Ba into
Loch Buidhe, Lochan na Stainge, and Loch Ba, which receives the out-
flow from Lochan na h-Achlaise, thence flowing into Loch Laidon,
thence into Loch Eigheach — an expansion of the river Gaur — receiving
the waters from Lochan Sron Smeur, and then flowing into Loch
Rannoch, which receives the outflow from Loch Ericht, flowing finally
into Loch Tummel, thence by the river Tummel into the river Tay at
Logierait.

(3) The Tay branch rises on the flanks of Ben Lui (Beinn Laoigh),
and flows by the river Fillan into Loch Dochart and Loch lubhair,
thence by the river Dochart into Loch Tay, being joined by the river
Lochay at Killin just before entering Loch Tay ; the outflow from Loch
Tay is carried into the estuary of the Tay by the river Tay, which is
joined shortly after leaving Loch Tay by the river Lyoii, bearing the
outflow from Loch Lyon, and further on (at Logierait) the river
Tummel, bearing the outflow from the Garry and Tummel branches,
still further on (at Dunkeld) by the river Bran, bearing the outflow
from Loch Freuchie, still further on (at Cargill) by the river Isla, and
still further on, shortly before reaching Perth, by the river Almond.

(4) The Earn branch takes its rise at the heads of Glen Ogle and
Gleann Ceann Droma, the two streams flowing into the west end of
Loch Earn, which receives also the waters of the Ample burn, Beich
burn, the Vorlich, the Tarkeii, and other smaller streams; the outflow
from Loch Earn passes at St. Fillans into the river Earn, which receives
the waters of the Ruchill and Lednock near Comrie, those of the Turret
bearing the outflow from Loch Turret, near Crieff, and other smaller
streams as it flows eastward to join the Tay at the head of the estuary.

Loch Ericht (see Plates XII. and XIII.). — Loch Ericht is a large
Highland loch situated partly in Perthshire and partly in Inverness-
shire, at a high elevation among the Grampians. It is one of the wildest
and most magnificent lochs of Scotland, presenting all along its shores
scenes of lonely grandeur and sublimity, the mountains rising from the
water's edge to great altitudes, their sides scarred by mountain torrents.
The surface, when measured by the Ordnance Survey officers in 1872,

THE FRESH-NVATKK U>< Us OF SCOTLAND. 55

was found to be 1153-4 feet above the level of the sea; it is thus one of
the most elevated of the larger Scottish lochs. It is known to anglers
as the home of large Salmo ferox, as well as of trout said to be equal
in quality to those of Loch Leven. It trends in a north-east and
south-west direction, and is broadest near the southern end, narrowing
gradually towards the northern end. It is over 14J miles in length,
and over one mile in maximum breadth; the mean breadth is about
half a mile, being 3J per cent, of the length. Its waters cover an area
of over 4600 acres (or nearly 1\ square miles), and it drains an area
seven times greater, or over 32,000 acres (nearly 50 J square miles).
The total number of soundings taken in Loch Ericht was 488, which
show that it is a comparatively deep loch, the greatest depth observed
being 512 feet. The mass of water contained in the loch is estimated at
38,027,000,000 cubic feet, and the mean depth at 189 feet, being 37
per cent, of the maximum depth. The length of the loch is 150 times
the maximum depth, and 405 times the mean depth.

The deepest part of the loch is in the southern broader portion,
where, about 3 \ miles from the foot of the loch, there is a small central
depression, about one-third of a mile in length, and covering about
58 acres, in which the depths exceed 500 feet, the maximum being
512 feet. There are two 400-feet depressions, the larger, about three
miles in* length, reaching to about 1J miles from the southern end,
and enclosing the 500-feet depression. Separated by about a quarter
of a mile from the northern end of the large 400-feet depression is
the second smaller isolated depression, in which the maximum depth
is 410 feet. There are two 300-feet depressions, the larger in the
southern portion of the loch, the smaller in the northern portion. The
southern depression is over 4J miles in length, and encloses the deepest
water in the loch. The northern s^maller depression is under one mile in
length, with a maximum depth of 314 feet, and approaches to within
2J miles of the head of the loch. There are two 200-feet depressions;
the larger runs from within a mile of the southern end to more than
half-way towards the northern end, being over seven miles in extreme
length. It is separated from the northern 200-feet depression by an
interval of 2J miles, in which the depth varies from 127 to 194 feet.
The northern 200-feet depression is nearly 2| miles in length, approach-
ing to within about 1J miles from the northern end, and enclosing the
small northern 300-feet depression already mentioned. The 100-feet
depression is a continuous area extending from within less than half a
mile of the southern end to within less than a mile of the northern end,
and is about 13 J miles in total length. The 50-feet depression follows
approximately the contour of the loch. Opposite Loch Ericht Lodge
an isolated sounding of 44 feet was observed between the 50- and 100-
feet lines, and about H miles farther down, opposite the entrance of
the Allt Camus nan Cnamh, another isolated sounding of 20 feet jyas
taken, surrounded by deeper water.

56 BATHYMETRICAL SURVEY OF

The area of the bottom of the loch between the shore and the
50-feet line is estimated at about 880 acres (or 19 per cent, of the total
area of the loch), that between the 50-feet and 100-feet contours is
estimated at 695 acres (or 15 per cent.) ; that between the 100- and
200-feet contours is estimated at about 1160 acres (or 25 per cent.);
that between the 200- and 300-feet contours at about 875 acres (or 19
per cent.) ; that between 300 and 400 feet at 476 acres (or over 10 per
cent.) ; that between 400 and 500 feet at about 474 acres (or over 10
per cent.); and that over 500 feet at 58 acres (or 1J per cent.).

It will thus be seen that Loch Ericht is of very simple conformation.
The deeper parts are divided into two basins, by the constriction in the
outline of the loch in the vicinity of Loch Ericht Lodge, where, in one
place, it is less than a quarter of a mile in width, but even here the
depth in the centre exceeds 100 feet.

Deposits. — The deposits from Loch Ericht are interesting because of
the evidence of layers of different colours. At a depth of 50 feet a red
sandy mud was obtained; at 112 feet the mud was white beneath and
brown on top; at 124 feet it was all brown; at 153 feet all brown; at
182 feet sandy and white ; at 184 feet white and brown ; at 245 feet the
deposit was a light-coloured mud, with a thin brown layer one inch in
thickness on the top; at 270 feet it was white below, black-brown
above ; at 366 feet the mud was all dark brown ; at 385 feet there was a
white clay or mud with a dark layer on the top; at 456 feet the mud
was all black ; at 497 feet a section of black mud 5 inches in thickness
was obtained; and at 510 feet the same black mud was found, without
any trace of the lighter-coloured mud.

The sand from 50 feet consisted largely of mineral particles (pro-
bably 70 per cent, of the whole deposit) with a mean diameter of about
0-6 mm., one or two rock fragments attaining a diameter of 7 mm. The
remainder of the deposit consisted of clayey and vegetable matter, with
minute mineral particles less than 0*05 mm. in diameter, Diatoms,
Sponge spicules, and Entomostracous skeletal remains. The light-brown
mud from 150 feet contained about 30 per cent, of mineral particles,
with a mean diameter of 0'5 mm., the largest being 5 mm. in diameter,
with clayey and vegetable matter, and organic remains as previously
mentioned. The dark-brown mud from 366 feet contained only about
10 per cent, of mineral particles (quartz, black and white mica, &c.)
exceeding 0-05 mm. in diameter, the mean diameter being about 0-2 mm.
Samples of the two different-coloured layers of mud from a depth of
385 feet were submitted to analysis, with the following results : —

Bottom layer. Top layer.

Organic matter lO'OO per cent 26 '8 per cent.

Insoluble residue .. ... 73*70 ,, 57'6 ,,

Iron oxide 13'64 ,, 17'2 ,,

97-34 101-6

THE FRESH- WATER LOCHS OF SCOTLAND 57

These analyses seem to show that the upper layer contained more
organic matter (presumably vegetable matter) and a little more iron
than the lower layer. Microscopic analysis of the two layers indicates
that the mineral particles were rather more numerous and larger in the
top layer, while the clayey matter seemed to be more abundant in the
lower layer.

Loch Garry (see Plate XV.). — Loch Garry* lies to the east of Loch
Ericht, at a still higher elevation, and the scenery round about is very-
wild ; the height of the surface of the loch above sea-level is not given
on the Ordnance Survey map, but a height of 1326 feet is shown near
the outlet, so that the level of the loch is probably about 1320 feet above
the sea. In trend and in outline it somewhat resembles Loch Ericht,
narrowing towards the northern end. It is over 2J miles in length,
the maximum width being over a quarter of a mile ; the mean breadth
is slightly under a quarter of a mile (being 9 per cent, of the length).
Its waters cover an area of about 390 acres (three-fifths of a square
mile), and it drains an area thirty-seven times greater (or about 22 J
square miles). The total number of soundings taken in Loch Garry was
141, the maximum depth observed being 113 feet. The mass of water
contained in the loch is estimated at about 846,000,000 cubic feet, and
the mean depth at nearly 50 feet (being 44 per cent, of the maximum
depth). The length of the loch is 119 times the maximum depth, and
260 times the mean depth.

Loch Garry forms a simple basin, except that the bottom sinks into
two depressions exceeding 100 feet in depth, separated by depths of 82
to 93 feet. The larger but shallower depression is situated in the
southern half of the loch, and is over a quarter of a mile in length, the
maximum depth therein observed being 105 feet. The smaller but
deeper depression is situated in the northern half of the loch, being only
about one-sixth of a mile in length, and containing the maximum depth
of the loch — 113 feet. The 75-feet, 50-feet, and 25-feet depressions form
continuous areas, following approximately the outline of the loch. The
75-feet depression is nearly 1| miles in length, the 50-feet depression
nearly 2 miles in length, and the 25-feet depression 2 J miles in length.

The area of the bottom between the shore and the 25-feet contour-
line is about 117 acres (or 30 per cent, of the total area of the loch);
that between the 25- and 50-feet contour-lines is about 83 acres (or 21
per cent.); that between 50 and 75 feet is almost the same; that
between 75 and 100 feet is about 87 acres (or 22 per cent.) ; and that
over 100 feet is about 19 acres (or 5 per cent.).

Temperature Observations. — The serial temperatures taken while
sounding out Lochs Ericht and Garry in June, 1900, are given in the

* This loch must not be confounded with the larger Loch Garry in Inverness-shire.

58

BATHYMETRICAL SURVEY OF

following table, and those taken in Loch Ericht are shown graphically
in the temperature section (Plate XIV.), since they are extremely
interesting as illustrating the effect of the wind upon the distribution
of temperature : —

Loch
Garry.

Loch Ericht.

Depth

1

in feet.

June 19,

June 20,

June £0,

June 16,

June 15,

June 20,

Juce 21,

1900, *

1900, 1J

1900, 3}

1900, 9J

1900, 5J

1900, 1

1900.

mile from

miles from

miles from

miles from

miles from

mile from

S. end.

S. end.

S. end.

N. end.

N. end.

N. end.

o

o

o

o

o

o

o

•0

57'0

47-3

49-0

50-0

500

53-2

55-1

5

47-0

48-7

497 I

6

,->()•<»

10

56-9

47-2

47 :8

49-5

...

25

49-9

30

49-5

46-1

47 ;5

48 :6

54 -2

40

45-8

50

44 :6

44-7

44-7

44 :8

52 :3

60

46-3

43-4

...

...

...

75

42-6

43 :2

44 :0

98

...

...

...

41 5

...

100

422

42-9

42 :6

105

46-0

...

120

...

...

...

...

427

150

41-3

200

41 :0

41-1

...

300

40-7

40'.-)

400

40-5

40-5

•. . .

500

40-:>

...

Loch Ericht. — Like Loch Katrine, Loch Ericht is said never to freeze
over, and the surface temperature remains comparatively low through-
out the summer. The surface temperatures taken in Loch Ericht
during the visit from 15th to 20th June show a range of 10°'4, viz.,
from 46°- 6 to 57° ; the higher temperatures were obtained towards the
northern end of the loch, and the lower temperatures towards the
southern end of the loch. A glance at the temperature section (Plate
XIV.), based upon the observations given in the table, shows that the
warmer water was all collected towards the upper end of the loch, as
the result of a south-easterly wind which blew at times during the six
days that were devoted to the survey of the loch, colder water having
been drawn up at the opposite end of the loch to supply the place of the
warmer surface water driven before the wind.

Loch Garry. — Loch Garry was visited on the 21st June, 1900, when
the surface temperature was found to vary from 57° at the south-west
end to 59°'4 at the north-east end, and this would seem to indicate a
distribution of temperature similar to that observed in Loch Ericht,
but since only one temperature series was taken, it is impossible to form
an idea of the distribution of temperature throughout the whole body
of water.

THE FRESH-WATER LOCHS OF SCOTLAND.

59

Rannoch Moor Lochs. — No coach road in Britain probably passes
through more magnificent scenery than that between the Bridge of
Orchy and Ballachulish. About half-way between Iiiveroran Hotel and
King's House Hotel the river Ba crosses the road, and to the west lies
Corrie Ba, the sanctuary of the Black Mount forest, where no shot is
ever fired, and consequently this splendid corrie is the home of the deer,
the golden eagle, the fox, and other wild animals. Here also is the
most westerly source of the rivers of the Tay basin. In rainy weather
a large amount of water passes down the river Ba and other streams
into the moor of Rannoch, and about a mile or two to the eastward of
the road a large extent of the moor is flooded, and presents the

FIG. 15. — MOOR OF RANNOCH, SHOWING LOCH BUIDHE AND LOCHAN NA STAINGE.
(Photograph by Sir John Murray.)

appearance of a vast lake. In drier weather there are distinct basins,
which have received the names of Loch Buidhe, Lochan na Stainge,
Lochan na h-Achlaise, and Loch Ba (or A-baw), all of them situated
in drift and encumbered with rocks and small islands; they are all
shallow. These lochs all contain trout, and have boats on them; they
belong to the Marquis of Breadalbane, and are strictly preserved. On
Eilean Molach in Loch Ba the heron still breeds in large numbers, and
formerly the osprey used to breed in the same place. In making the
survey of these lochs, the staff were much obliged to Mr. M'Intyre, the
head stalker to the Marquis of Breadalbane.

60 BATHYMETRICAL SURVEY OF

Loch Buidhe (see Plate XVI.). — Loch Buidhe (or Buie) is very
shallow, and in places covered with weeds, though its surface is
practically free from islands. It is somewhat quadrangular, though
irregular, in outline, the maximum diameter (or length) from east
to west being about one-third of a mile, and the maximum breadth
from north to south about a quarter of a mile, the mean breadth being
about one-sixth of a mile. Its waters cover an area of about 35 acres,
or one-nineteenth of a square mile, and it drains an area 222 times
greater, or over 11 square miles. It is deepest towards the eastern
shore, where the maximum depth (3 feet) was observed in several
places, shoaling towards the western shore, off which the weeds are
most abundant; the volume of water contained in it is estimated at
2,265,000 cubic feet. It was surveyed on April 15, 1902, about 40
soundings being recorded. The surface of the water was determined
by the Ordnance Survey officers in 1897 as being 981 feet above sea-
level. The temperature of the surface water at 7 p.m. on April 15,
1902, was 48° Fahr.

Lochan no, Stainge (see Plate XVI.). — Lochan na Stainge (or
na-Sting) is extremely irregular in outline, and includes three com-
paratively large islands, as well as a number of small ones. Its
length from north to south is over half a mile, the maximum breadth
being two-fifths of a mile, and the mean breadth about one-seventh
of a mile. Its waters cover an area of over 51 acres, or rather more than
one-twelfth of a square mile, and it drains directly about two-thirds
of a square mile, but, since it receives the outflow from Loch Buidhe,
its total drainage area is nearly 12 square miles, or 147 times the area
of the loch. The loch is divided into two portions by a barrier at the
central constriction, on which there is only 1 foot of water, the
maximum depth observed in the northern portion (between the large
island and the northern shore) being 8 feet, while the maximum depth
of the loch (14 feet) was found in the southern portion immediately to
the south of the barrier referred to. The volume of water contained in
the loch is estimated at 11,407,000 cubic feet, and the mean depth at
5 feet. The loch is on the whole shallow, nearly 99 per cent, of its
floor being covered by less than 10 feet of water. It was surveyed on
April 19, 1902, 55 soundings being recorded. The level of the loch was
not determined by levelling, but on the new edition of the Ordnance
Survey map (1897) there is a spot-level of 972 feet on the southern
shore near the inflow, and another of 968 feet on the northern shore at
the outflow, so that the surface of the water is probably about 970 feet
above the sea. The drift-marks around the loch showed that it some-
times rises 5 feet higher than on the date surveyed, and during floods
the whole valley looks like one loch, with knolls projecting above the
water. The temperature of the surface water at i0.30 a.m. on April

THE FRESH-WATER LOCHS OF SCOTLAND.

61

19, 1902, near the boathouse was 43°, and on returning to the same
place at 12.30 (noon) it had risen to 46°*4; in the main basin, near the
centre, the surface temperature was 42°'6.

Lochan na h-Achlaue (see Plate XVI.). — Lochan na h-Achlaise (or
na-Hachlich) is irregular in form, the outline being somewhat triangular
or heart-shaped, with the apex pointing south. It includes many larger
and smaller islands, and the bottom in the shallower places is covered
by stones and boulders. The length from north to south is over four-
fifths of a mile, while the maximum breadth from east to west is about
three-quarters of a mile, the mean breadth being over one-third of a

FIG. 16. LOCHAN NA H-ACHLAISE.

(Photograph l>!f R. M. Clark. B.Sc.)

mile. Its waters cover an area of about 183 acres, or nearly three-
tenths of a square mile, and it drains an area of over one square mile,
or nearly four times the area of the loch. The north-western portion
of the loch is shallow, the deeper water being found in the southern and
eastern portions. The 10-feet basin is a continuous area, extending
from near the southern shore in a northerly and then north-easterly
direction to near the north-eastern shore, excluding the islands lying
off the eastern shore, and is nearly three-quarters of a mile in length.
The 10-feet basin includes two 20-feet basins, the more southerly being
the larger and deeper, the maximum depth of the loch (28 feet) having

62 BATHYMETRICAL SURVEY OF

been found towards the north-eastern end of this basin, and com-
paratively close to the eastern shore. The volume of water contained
in the loch is estimated at 76,236,000 cubic feet, and the mean depth
at 9J feet. The loch is on the whole comparatively shallow, about 63
per cent, of the bottom being covered by less than 10 feet of water,
while only 9 per cent, of the bottom is covered by over 20 feet of water.
The loch was surveyed on April 16, 1902, over 100 soundings being
recorded. The surface of the water was found to be 962 feet above
sea-level by the officers of the Ordnance Survey in 1897. The tem-
perature of the surface water at 6 p.m. on April 16, 1902, was 450-2.

Loch Bd (see Plate XVI.). — Loch Ba (or A-baw) is extremely
irregular in outline, studded with large and small islands, and with
many rocks and boulders. Its length from south-west to north-east in
a straight line is over 2 miles, and following the axis of deep water
about 2J miles. Its maximum breadth in the southern portion from
east to west is over a mile, and the mean breadth is nearly half a mile.
Its waters cover an area of about 585 acres, or nine-tenths of a square
mile, and it drains directly an area of 4J square miles, but, since it
receives the outflow from Loch Buidhe, Lochan na Stainge, and
Lochan na h-Achlaise, its total drainage area is nearly 17^ square miles,
or nineteen times the area of the loch.

The bottom of Loch Ba is very irregular. The deepest water occurs
in the northern portion between the islands of Eileaii Molach and
Eilean na h-Iolaire, where there is a small basin less than a quarter of
a mile in length, and over 20 feet in depth, the maximum depth of
30 feet having been observed about one-sixth of a mile to the north of
the northern point of Eilean Molach. An isolated sounding of 20 feet
was taken close to the western shore of the southern portion of Eilean
Molach. There are three irregular basins with depths exceeding 10
feet : the central one, enclosing the 20-feet basin, and extending on both
sides of Eilean Molach and to the west and north of Eilean na h-Iolaire,
is nearly three-quarters of a mile in length and over a quarter of a mile
in breadth ; the southern one, occupying the wide south-eastern portion
of the loch, is nearly half a mile in maximum diameter ; and the third,
situated in the north-eastern extension of the loch, is nearly half a mile
in length and nearly a quarter of a mile in breadth. The volume of
water contained in the loch is estimated at 206,497,000 cubic feet, and
the mean depth at 8 feet, being 27 per cent, of the maximum depth.
The length of the loch is 378 times the maximum depth and 1402 times
the mean depth. Over 70 per cent, of the floor of the loch is covered by
less than 10 feet of water, and only 1| per cent, by more than 20 feet of
water. The loch was surveyed on April 17 and 18, 1902, over 300
soundings having been taken. The level of the loch was' determined by
the Ordnance Survey officers in 1897 as being 957 feet above sea-level.

THE FRESH- WATER LOCHS OF SCOTLAND.

63

The temperature of the surface water near the boathouse, when com-
mencing the survey at 2.45 p.m. on April 17, was 50°'8 Fahr., but
later on, out in the open water, the surface temperature was 44°'2
Fahr. ; on the 18th at noon the surface temperature near the shore
was 50°-0 Fahr., while in the bay to the north of the boathouse the
temperature was 46°-0 Fahr.

Lochan Beinn Caorach and some other small basins of water in

FIG. 17. — HERONS' NESTS ON EILEAN MOLACH IN LOCH BA.
(Photograph by T. N. Johnston, .!/.«., C.M., F.R.S.E.)

this region were without boats and could not be sounded; they were
evidently all quite shallow and of the same character as Loch Buidhe.

Loch Laidon (see Plate XVII.). — Loch Laidon (or Lydoch, or
Luydan) lies partly in Perthshire and partly in Argyllshire, the
boundary running along the centre of the western arm and for a
certain distance up the main loch. It is one of the best trouting lochs

64 BATHYMETRICAL SURVEY OF

in the district, or perhaps in Scotland. It is about 5J miles in length
from north-east to south-west, but it sends out an arm towards the
west, which is over 1J miles in length, and a line following the axis of
the loch from the north-east end to the extremity of the western arm
would be over 6 miles in length. Its maximum breadth is nearly
three-quarters of a mile, and the mean breadth about one-third of a
mile, or 6-4 per cent, of the length. Its waters cover an area of about
1149 acres, or over 1| square miles, and it drains directly an area of
30J square miles; but, since it receives the outflow from Lochs Ba,
Achlaise, Stainge, and Buidhe, its total drainage area is over 47| square
miles or 26J times the area of the loch. Nearly 500 soundings were
taken in the loch, and the maximum depth observed was 128 feet, the
mean depth being 35 feet, or 27 J per cent, of the maximum depth. The
length of the loch is 219 times the maximum depth, and 795 times the
mean depth. The volume of water contained in the loch is estimated at
1,761,733,000 cubic feet. The western extension and the southern end
of Loch Laidon are filled with boulders and islets, and are like Loch Ba
in character, but the main basin is of comparatively simple form,
though with minor undulations of the lake-floor, the deepest water
occupying the centre of the loch, where there is a basin three-quarters
of a mile in length and over 100 feet in depth, the maximum depth of
128 feet having been observed about 2| miles from the south-west end
and 2J miles from the north-east end. Separated from this main
100-feet basin by shallower water, there is a sounding of 104 feet a short
distance to the south-west, and half a mile further south there is an
isolated sounding of 100 feet; there is also an isolated sounding of 100
feet a quarter of a mile to the north-east of the main basin. The
principal 50-feet basin extends from less than a mile from the south-
west end to less than 1J miles from the north-east end, and is nearly
3 miles in length. Separated from this larger basin by an interval of
a quarter of a mile is a smaller one, about one-third of a mile in length,
situated in the north-eastern part of the loch, and nearly midway
between them is an isolated sounding of 50 feet. The western arm of
Loch Laidon is shallow and filled with rocks and boulders, the greatest
depth observed being 17 feet in three different places. Of the entire
lake floor, 53 per cent, is covered by less than 25 feet of water, 21 per
cent, is covered by water between 25 and 50 feet in depth, 22 per cent,
by water between 50 and 100 feet in depth, and 4 per cent, by water
exceeding 100 feet in depth. Loch Laidon was surveyed on April 9 to
25, 1902, and the surface of the loch was found by levelling to be 923-9
feet above sea-level. When surveyed by the Ordnance Survey officers
on July 28, 1860, the level of the loch was 924-6 feet above the sea.
At the north-eastern end of Loch Laidon is a small basin called Dubh
Lochan, which was found by levelling on April 14, 1902, to be 2 feet
higher than Loch Laidon, and should therefore, strictly speaking, be

THE FRESH-WATER LOCHS OF SCOTLAND.

65

looked upon as a distinct lake, but in the foregoing description the two
lakes have been regarded as one. Many temperature observations were
taken in Loch Laidon on April 9, 10, 14, 15, and 25, the surface
readings varying from 38°'8 at 5 p.m. on the 9th to 480-2 at the head of
the loch at 1 p.m. on the 10th — a range of 9°-4 in the temperature of
the water, while the range in the air-temperature during the same
period was only 5° (from 45°-2 to 50°-2). Two serial temperature
observations were taken in the centre of the loch, the first at 5 p.m. on
April 9, when the readings were identical (39°-8) at the surface and at
depths of 5 and 25 feet, the second at 5.20 p.m. on the 10th, when the

FIG. 18. LOCH LAIDON.

(Photograph by Miss Marynret Murray.)

surface readings were 39°-8 and 41°, that at 5 feet 39°'7, and that at
20 feet 390>4. The surface temperature in Dubh Lochan on April 14
was 43°-9.

The western arm of Loch Laidon receives the waters from a small
loch (Lochan Gaineamhach) lying about 2 miles to the west. This
loch, and the neighbouring "one to the north, were visited on May 20,
1903, but, as there were no boats on tjiem, they were not sounded.
They were found to be of the same general character as the other lochs
of Rannoch Moor — shallow, with stony shores, containing boulders
and islets, some of the latter with small trees on them. In Lochan
Gaineamhach, weeds were seen only in some very small bays, but in

66

BATHYMETRICAL SURVEY OF

the other lochan weeds were seen in several places, with a little open
water in the eastern half.

To the north of the north-eastern end of Loch Laidon lies the
little Lochan a' Chlaidheimh, where three counties (Perthshire,
Argyllshire, and Inverness-shire) meet. This lochan was visited on
May 14, 1902, but was not sounded, as there was no boat on it. It is
evidently very shallow in all parts, full of rocks and boulders, a rock
showing above water even in the very centre, and all along the shores
rocks are numerous, extending in lines out from the shore. A couple of
miles to the east of Lochan a' Chlaidheimh lies Lochan Sron Smeur,
next to be dealt with, on which there was a boat.

FIG. 19. LOCHAN SRON SMEUR.

(Photograph by H. C. Lamb.)

Lochan Sron Smeur (see Plate XVIII.). — Lochan Sron Smeur (or
Sron Smear) is situated a little to the east of the road running from
Rannoch to Loch Ossian, and is said to contain small black trout, but
is strictly preserved. It is over half a mile in length, less than a quarter
of a mile in maximum breadth, the mean breadth being one-seventh of
a mile, or 25 per cent, of the length. Its waters cover an area of over
50 acres (or about one-twelfth of a square mile), and it drains an area of
nearly two square miles, nearly twenty-four times the area of the loch.
It was surveyed on May 12, 1902, the maximum depth observed being
33 feet. The volume of water contained in the lake is estimated at
22,592,000 cubic feet, and the mean depth at 10'3 feet, or 31 per cent,
of the maximum depth. The loch is of simple conformation, the western

THE FRESH- WATER LOCHS OF SCOTLAND. 67

half being comparatively shallow, while the deeper water occurs in the
eastern half, the maximum depth having been found about one-eighth of
a mile from the eastern end. The 10-feet basin approaches quite close to
the eastern shore, and is about one-third of a mile in length, enclosing
the 20-feet basin, which is about one-fifth of a mile in length. About
61 per cent, of the lake-floor is covered by less than 10 feet of water,
while about 12 per cent, is covered by over 20 feet of water. No
bench-marks were found near the loch, but a little distance up the river
which feeds it there is a spot-level of 1134 feet. There was little
evidence of much rise and fall in the level of the water, the range
possibly not exceeding 2 feet. The temperature of the surface water
varied from 470-4 to 50°'5, a range of 3°'l, the higher readings being
taken in shallow water near shore. Readings at 10 feet and at 20
feet near the centre of the loch gave 48° in each case, the surface
temperature at the same time being 47°:6.

Less than a mile to the east of Lochan Sron Smeur is Lochan Loin
nan Donnlaich (or Lochan Loin nan Dubhach, or Loch-an-Londonich),
said to contain large trout. When visited, many rocks and boulders
were observed showing above the water, and grass filled the bay at
the outlet.

Loch Eiglieach (see Plate XVIII.). — Loch Eigheach (or Eaigh),
about 3 miles from where the river Gaur passes its waters into Loch
Rannoch, is an expansion, or rather three expansions, of the river
Gaur, the two western expansions lying on a higher level than the
eastern one, and hence strong currents run in an easterly direction.
In high floods the whole area is practically submerged. A large part of
the loch is covered by reeds, and the bottom is very weedy. The entire
loch is nearly nine-tenths of a mile in length, with a maximum breadth
of less than a quarter of a mile, the mean breadth being one-tenth of a
mile. Its waters cover an area of about 59 J acres, or less than one-tenth
of a square mile, and it drains directly an area of nearly 14 square
miles, but since it receives the outflow from Lochan Sron Smeur and
from Lochs Laidon and Ba, &c., its total drainage area is nearly 63 J
square miles, or 705 times the area of the loch. The loch was surveyed
on April 21, 1902, about 80 soundings being recorded, the maximum
depth observed being 28 feet. The surface of the eastern expansion
was found by levelling to be 818-2 feet above sea-level, and the water
apparently rises about 3 J feet above its level on the date surveyed. The
volume of water contained in the loch is estimated at 15,794,000 cubic
feet, and the mean depth at 6 feet, or 22 per cent, of the maximum
depth. The eastern expansion is the deepest, the maximum depth of
28 feet having been found to the west of the island near the east end
of this expansion ; the north-western expansion has a maximum depth
of 7 feet observed not far from the outlet, but the majority of the

68 BATHYMETRICAL SURVEY OF

soundings run from 2 to 5 feet; the south-western expansion is the
shallowest, with a maximum depth of 3 feet to the west of the central
large island (Eilean na Coille), the bottom to the east and south of that
island being covered by only 1 foot of water. Over 90 per cent, of the
entire lake-floor is covered by less than 10 feet of water, and less than
2 per cent, by over 20 feet of water. The surface temperature in the
eastern expansion at 11 a.m. on April 21, 1902, was 44°-2.

Loch Rannoch (see Plate XIX.). — Loch Rannoch, one of the larger
and more important of the lochs in the Tay basin, was the headquarters
of the Lake Survey for nearly four months, from March 20 to July 10,
1902, and during that period a great many soundings, as well as
observations on the temperature of the water, on the biology, and on the
rise and fall of the surface of the loch, were taken, all the members of
the staff taking part in the work. The lake trends in an east-and-west
direction, and is a lovely sheet of water, the hills on both sides, and the
woods clothing its shores in many places, adding beauty to the scene.
The famous Black Wood of Rannoch on the south side is of great
antiquity. The loch contains many small trout, and is famed for large
Salmo ferox. It is nearly 9| miles in length, considerably over a mile
in maximum breadth, the mean breadth being about three-quarters of
a mile, or about 8 per cent, of the length. Its waters cover an area of
over 4700 acres, or nearly 7 \ square miles, and it drains directly an area
of about 130 square miles, but, since it receives the outflow from Loch
Ericht, Loch Eigheach, Loch Laidon, Loch Ba, &c., its total drainage
area is about 243| square miles, or 33 times the area of the loch.

Over eight hundred soundings were taken in Loch Rannoch, the
maximum depth observed being 440 feet, or 20 feet deeper than the
maximum depth recorded by Mr. Grant- Wilson during his survey in
the year 1888, when he took about 320 soundings. The volume of
water contained in the loch is estimated at about 34,387,131,000 cubic
feet, or less than a quarter of a cubic mile, and the mean depth at 167|
feet, or 38 per cent, of the maximum depth. The length of the loch
is 116 times the maximum depth, and 306 times the mean depth. The
loch is widest and deepest in the eastern half, narrowing and shallow-
ing towards the west on approaching the island Eilean nam Faoileag,
then deepening again to the west of that island. It consists of one
large main basin, with two subsidiary small basins over 50 feet in
depth towards the west end, separated from the main basin by the
shallow water in the neighbourhood of Eilean nam Faoileag. The
larger of the two subsidiary basins is about three-quarters of a mile in
length, stretching from south of the island An t-Eilean Fearna, at the
entrance of the river Ericht, towards the west end of the loch, and the
maximum depth recorded in it was 84 feet; the smaller basin lies
between the two islands mentioned and towards the northern shore,

THE FRESH \\ATKR LOCHS OF SCOTLAND.

69

soundings of 52 and 54 feet having been obtained therein. The main
50-feet basin is about 7| miles in length, occupying the great body of
the loch east of Eilean nam Faoileag, and covering an area exceeding

5 square miles. The 100-feet basin is nearly 7 miles in length, extend-
ing from between the mouths of the Killichonan burn and the Allt
Camghouran towards the east end of the loch. The 200-feet basin is

6 miles in length, stretching from within a quarter of a mile from the

FIG. 20. LOCH RANNOCH.

(Photograph by Miss M'Pherson.)

east end to opposite the house Talla Bheith on the northern shore. The
main 300-feet basin is nearly 4 miles in length, stretching from less
than half a mile from the east end to opposite Dall on the southern
shore, and separated from it by an interval of a quarter of a mile is an
isolated sounding of 304 feet. Within the 300-feet basin the bottom
sinks in three places along the central axis of the loch below the 400-
feet line. The easternmost of these three 400-feet basins is the largest
and deepest, situated about 1 J miles from the east end, about two-thirds

70 BATHYMETRICAL SURVEY OF

of a mile in length, and enclosing the maximum depth of the loch (440
feet); a short distance to the west (opposite Craiganour) is a second
small basin based upon a sounding of 404 feet ; and three-quarters of a
mile farther west is the third basin, with a maximum depth of 421
feet. The area of the lake-floor covered by less than 50 feet of water
is about 1200 acres (nearly 2 square miles), or 25 per cent, of the total
area, while the area between the 50-feet and 100-feet lines is about 750
acres, or 16 per cent., showing a relatively rapid descent beyond the
50-feet line. The area between the 100- and 200-feet lines is about
877 acres, or nearly 19 per cent, of the entire area. The area between
the 200- and 300-feet lines is about 950 acres, or over 20 per cent.,
the area between the 300- and 400-feet lines is about 875 acres, or 18J
per cent., and that over 400 feet about 65 acres, or nearly 1 J per cent.,
of the total area of the loch.

On commencing the survey of Loch Rannoch, the height of the
surface above sea-level was determined from Ordnance Survey bench-
marks as 668 feet ; the level of the loch fluctuated during the progress
of the survey, but the soundings have all been reduced to this datum.
The officers of the Ordnance Survey on July 19, 1860, found the level
of the loch to be 667 -5 feet above the sea.

Temperature Observations. — Very many temperature observations
were taken between March 20 and July 10, 1902. The surface tem-
peratures need not be discussed in detail ; the lowest reading recorded
was 37°-9 on March 28, and the highest 59°-8 on June 23, showing a
range of 22° in the temperature of the surface water during the period
of three months. An interesting series of hourly observations on the
temperature of the air and of the surface water at the pier at Rannoch
Lodge was taken on June 9. One thermometer was immersed in 3 feet
of water outside the pier, and another in 1 foot of water inside the pier,
and they were read simultaneously with an air-thermometer at intervals
of one hour from 9 a.m. to 10 p.m. The temperature of the air rose
gradually, though irregularly, from 48° at 11 a.m. to a maximum of
53° at 4 p.m., falling gradually again to 44°'5 at 9 p.m., and 45° at
10 p.m. The thermometer in 3 feet of water showed a gradual rise in
the temperature from 51°-9 at 9 a.m. to 53° at 11 a.m., then a slight fall
at noon (52°-7) and at 1 p.m. (52°'5), the maximum (53°- 6) being
recorded at 2 p.m., falling to 52°-9 at 4 p.m., rising to 53°-3 at 5 p.m.,
falling gradually to 52°'l at 8 p.m., then rising to 52°-8 at 9 p.m., and
53° at 10 p.m. The thermometer in 1 foot of water showed a gradual
rise in the temperature from 51°'4 at 9 a.m. to the maximum of 53°- 6 at
2 p.m., whence it fell gradually to 51°'5 at 9 p.m., the reading at
10 p.m. being 52°. The maximum temperature of the water was
recorded in each case at 2 p.m., while the maximum temperature of the
air was recorded at 4 p.m., and the temperature of the air was always
lower than that of the water, except when the air was at its maximum

THE FRESH -WATER LOCHS OF SCOTLAND.

71

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72 BATHYMETRICAL SURVEY OF

(53° at 4 p.m.), the thermometer in 3 feet of water then reading 52°-9,
while that in 1 foot of water read 53°*3. The temperature recorded in

1 foot of water was lower than that recorded in 3 feet of water in the
forenoon and late evening, but at noon and 1 p.m. it was higher, at

2 p.m. and 3 p.m. it was identical, and from 4 p.m. till 8 p.m. it was
higher, the greatest difference recorded being 10>3 at 9 p.m. (52°-8 at

3 feet, and 51°'5 at 1 foot).

The temperatures taken beneath the surface have been collected
together and arranged chronologically in the foregoing table, which may
be useful for future reference and comparison. The great majority of
them were taken in the small 80 -feet basin towards the west end of the
loch, while one series was taken near the east end on April 3, and three
series were taken towards the middle of the loch, opposite Craiganour,
on May 1, 2, and 23. The table shows well the heating up of the
water with the advance of summer. The readings taken near the west
end in March are all below 39° Fahr. — that is, below the maximum
density point, though surface temperatures exceeding 39°, and in one or
two cases exceeding 40°, were recorded near the shore during the last
days of March. On April 2 and subsequently, the temperature was
above that of maximum density (39°'l), but the observations taken near
the east end 011 April 3 showed that the temperature of the water from
surface to bottom was just below maximum density point. The water
in the small western basin had a temperature under 40° up to April 10,
and was practically uniform from top to bottom, but on April 21 and
subsequently the temperature rose, and there was a considerable range
between the temperature of the upper and lower layers. The water in
the main basin had a temperature of 40° at 200 and 300 feet on May 1 ;
on May 2 the temperature was 40°-2 at 200 feet; and on May 23 it
was 41°-9 at 100 feet. By the beginning of June the water near the
surface had attained a temperature of 50°, and by June 21 that
temperature extended down to 50 feet, the upper 10 feet having on
that date a temperature of 52°.

Loch Lyon (see Plate XXI.).— Loch Lyon lies at a high elevation
at the head of Glen Lyon, amid grand and mountainous scenery, its
waters being carried by the river Lyon into the river Tay a short
distance above the mouth of Loch Tay; it contains both salmon and
trout. It trends in a north-east and south-west direction, and is
extremely simple both in outline and in the conformation of the bottom.
It is of nearly uniform width, except for a cone of alluvium, brought
down by the river, on the south-eastern shore. It is about 1| miles in
length, with a maximum breadth of over a quarter of a mile, the mean
breadth being over one-fifth of a mile, or 12 per cent, of the length.
Its waters cover an area of about 236 acres, or over one- third of a square
mile, and it drains an area of over 10J square miles, an area nearly

THE F1M-:>U- \\.\TKR LOCHS OF SCOTLAND.

73

twenty-nine times greater than that of the loch. Over 100 soundings
were taken in Loch Lyon, the maximum depth observed being 100 feet.
The volume of water contained in the loch is estimated at about
460,750,000 cubic feet, and the mean depth at 45 feet, or 45 per cent,
of the maximum depth. The length of the loch is 92 times the maximum
depth, and 205 times the mean depth. As stated, the loch forms a
simple basin, the bottom sinking gradually on all sides towards the
deepest part, which is approximately centrally placed. The deep water,

FIG. 21. LOCH LYON.

(Photograph by Sir John Murray.)

however, approaches much closer to the south-west end than to the
north-east end, where the 25-feet line is distant about a quarter of a
mile from the shore, probably through silting up of the lake-floor at that
end. The 25-feet basin is nearly 1£ miles in length, the 50-feet basin
is about 1J miles in length, and the 75-feet basin is about 1J miles in
length. The area of the lake-floor covered by less than 25 feet of water
is about 92 acres, or 39 per cent, of the total area of the loch ; the area
between the 25- and 50-feet contour-lines is about 36 acres, or over
15 per cent. ; the area between the 50- and 75-feet contours is about

74 BATH Y METRICAL SURVEY OF

55 acres, or over 23 per cent. ; and the area over 75 feet in depth is
about 53 acres, or less than 23 per cent, of the entire area of the loch.
The comparatively flat-bottomed character of the deep basin is indicated
by the larger proportion of the bottom covered by water between 50
and 75 feet in depth, as compared with the proportion covered by water
between 25 and 50 feet, the average slope being thus considerably steeper
in depths of 25 to 50 feet than in depths of 50 to 75 feet ; and this latter
gentler slope is continued into the deeper water over 75 feet in depth,
as shown by the nearly equal areas on both sides of the 7 5 -feet line.
The large proportion under 25 feet in depth is due to the considerable
silted-up area towards the north-east end of the loch already referred to.
Loch Lyon was surveyed on May 10, 1902. No bench-marks were to be
seen along the shores, nor on the Ordnance Survey charts, but the
height of the surface of the loch was estimated as being about 1050 feet
above the sea. Lines of drift were observed 4 feet above the water,
which, according to the keeper, was about its normal height at the time
of the survey ; the water rises suddenly and falls as quickly, and might
fall perhaps a foot lower than on the date of the survey. Thus a range
of about 5 feet in the level of the water is indicated. The temperature
of the surface water on May 10, 1902, when commencing the survey,
about noon, was 48°'7 at the edge of the bank at the north-east end,
and readings taken along the shore gave 50°, 51°-8, 52°-5, and 58°. In
the afternoon, readings of 47°*9 were taken in shallow water towards the
northern shore, 48°'9 near the south-west end, and 460>4 in the centre
of the loch. These observations show a range of ll°-6 in the temperature
of the surface water throughout the day, viz. from 46°-4 to 58°.

Loch Dochart (see Plate XX.). — Loch Dochart, situated at the foot
Ben More amid beautiful scenery, is the westernmost of the lochs
belonging to the Tay branch of the Tay river-system, being evidently
an expansion of the river Fillan, which forms the headwaters of this
branch. It receives the drainage from a considerable tract of country,
is very shallow, the bottom is very weedy, and there are many reeds,
especially at the west end. Loch Dochart is nearly two-thirds of A
mile in length, with a maximum breadth of nearly one-sixth of a mile,
the mean breadth being over one-tenth of a mile, or 18 per cent, of the
length. Its waters cover an area of about 46 acres, or nearly one-
fourteenth of a square mile, and it drains an area of nearly 39 square
miles, or 555 times the area of the loch. Nearly 70 soundings were
taken in Loch Dochart, the maximum depth observed being 1 1 feet ;
but this depth is of very limited extent, only two isolated soundings
being recorded near the west end of the loch, while by far the greater
portion of the bottom is covered by less than 5 feet of water. The
volume of water contained in the loch is. estimated at 10,032,000 cubic
feet, and the mean depth at 5 feet, or 46 per cent, of the maximum

THE FRESH- WATER LOCHS OF SCOTLAND. 75

depth. The length of the loch is 298 times the maximum depth, and
652 times the mean depth. Loch Dochart was surveyed on April 28,
1902, and the level of the surface of the water was determined from
Ordnance Survey bench-mark as being 513 feet above sea-level. The
temperature of the surface water at 11.30 a.m. on that date was 500>1.

Loch lubhair (see Plate XX.). — Loch lubhair (or Nubhair) receives
the outflow from Loch Dochart by a river considerably less than half a
mile in length, so that they may almost be regarded as forming one lake.
It affords fair trout-fishing, and the scenery round about is very
beautiful. Loch lubhair is about 1J miles in length, with a maximum
breadth of about one-third of a mile, the mean breadth being nearly
one-sixth of a mile, or 12 per cent, of the length. Its waters cover an
area of about 135 J acres, or over one-fifth of a square mile, and it drains
directly an area of about 5J square miles; but, since it receives the
outflow from Loch Dochart, its total drainage area is over 44J square
miles, or 212 times the area of the loch. Over 100 soundings were taken
in Loch lubhair, and the maximum depth observed was 65 feet. The
volume of water contained in the loch is estimated at 147,284,000 cubic
feet, and the mean depth at 25 feet, or 38 per cent, of the maximum
depth. The length of the loch is 110 times the maximum depth, and 286
times theKmeaii depth. Loch lubhair trends in a north-east and south-
west direction, and is rather peculiar in outline, resembling somewhat
the italic letter /, constricted in the central portion, where a ridge crosses
the loch with a maximum depth of 36 feet on it. The loch widens and
deepens on each side of this constriction, the maximum depth of the
loch having been found in the north-eastern part, where the loch is
widest, the greatest depth observed in the south-western part being
49 feet. The 25 -feet basin is a continuous area over a mile in length,
approaching close to the northern shore, but distant about a quarter
of a mile from the south-west end. The area of the lake-floor covered
by less than 25 feet of water is about 72 acres, or 53 per cent, of the
total area of the loch ; the area between the 25- and 50-feet contours is
about 59 acres, or 44 per cent., while the area covered by over 50 feet
of water is about 5 acres, or 3 per cent, of the entire area of the loch.
Loch lubhair was surveyed at the same time as Loch Dochart, on April
28, 1902, the level of its surface being a foot lower than that of Loch
Dochart, viz. 512 feet above the level of the sea.

Loch Earn (see Plate XXII.). — Loch Earn is situated amid lovely
surroundings, the hills on both sides being clothed with rich woods, and
splendid mountain scenery bounds the horizon towards the west, while
on the south Ben Vorlich towers to a height of 3200 feet. It contains
trout and salmon, and also Salmo ferox. It has been said that the loch
is 100 fathoms ( = 600 feet) deep in some places, but this is disproved by

76 BATHYMETRICAL SURVEY OF

the soundings taken by different surveyors. Mr. Grant- Wilson took
over 180 soundings in 1888, Sir John Murray and the late Mr. F. P.
Pullar took about 150 soundings in 1900, and the Lake Survey took 500
soundings in 1902, but in no case was the depth found to exceed 288
feet. On the accompanying map only the Lake Survey soundings are
laid down, and the contour-lines drawn in from them.

Loch Earn is 6J miles in length, and four-fifths of a mile in maximum
breadth, the mean breadth being three-fifths of a mile, or 9J per cent,
of the length. The waters of the loch cover an area of over 2400
acres, or nearly 4 square miles, and it drains an area of over 54J

FIG. 22. LOCH EARN.

(Photograph by J. Parsons, B.Sc.)

square miles — an area fourteen times greater than the area of the
loch. Five hundred soundings were taken in Loch Earn, the maximum
depth observed being 287 feet, which agrees very well with the
maximum recorded by Mr. Grant-Wilson in 1888, viz. 48 fathoms,
or 288 feet. The volume of water contained in the loch is estimated
at 14,420,638,000 cubic feet, and the mean depth at 138 feet, or 48
per cent, of the maximum depth. The length of the loch is 118 times
the maximum depth, and 245 times the mean depth.

Loch Earn forms a simple basin, the lake-floor sinking gradually on
all sides down to the greatest depth, as is well shown by the longitudinal
and three cross-sections on the map. The 50-feet contour-line follows

THE FRESH- WATER LOCHS OF SCOTLAND. 77

approximately the outline of the loch, approaching very close to the
west end, where between the mouths of the Ogle and Kendrum burns
a sounding of 57 feet was taken about 300 feet from the shore, giving a
slope of 1 in 5'3. At the opposite end of the loch the 50-feet contour is
met with about one-third of a mile from the bridge across the river at
St. Fillans. The 100-feet basin approaches to within less than a quarter
of a mile from the west end, and less than half a mile from the east end,
and is over 5| miles in length; it covers an area of nearly 2J square
miles. The 200-feet basin is 4J miles in length, stretching from three-
quarters of a mile from the west end to 1£ miles from the east end, and
covers an area of 1J square miles. The 250-feet basin is nearly 2 miles
in length, and a quarter of a mile in maximum width, extending from
1 J miles from the west end to 3 miles from the east end. The maximum
depth of 287 feet was observed near the centre of the loch, between the
mouths of the Allt Bhacaidh on the north and the Allt Dhunain on the
south, about 2| miles from the west end, and 3| miles from the east
end. The area of the lake-floor covered by less than 100 feet of water
is about 926 acres, or 38 J per cent, of the total area of the loch ; the
area between the 100- and 200-feet contour-lines is about 755 acres, or
3H per cent. ; and the area covered by more than 200 feet of water is
about 700 acres, or 30 per cent. The flat-bottomed character of the
loch is indicated by the last-mentioned percentage, which is nearly
equal to the preceding one, though the interval of depth is only 87 feet
as compared with the previous interval of 100 feet. The comparatively
uniform average slope from the shore down to a depth of 100 feet is
shown by the fact that the areas on each side of the 50-feet line are
nearly equal, viz. 477 acres (or nearly 20 per cent, of the entire area of
the loch) between the shore and the 50-feet contour, and 449 acres (or
nearly 19 per cent.) between the 50- and 100-feet contours.

Loch Earn was surveyed on May 14 to 19, 1902, and the level of the
surface of the water \vas determined by levelling from Ordnance Survey
bench-mark as 317-2 feet above sea-level. This is identical with the
level determined by the surveyors of the Ordnance Survey on August
25, 1899.

Temperature Observations. — On May 14, at 3.45 p.m., the tem-
perature of the surface water near Lochearnhead was 46°'l ; at 6 p.m.
the surface temperature was 44°, and at 7 p.m. near the shore 47°'2.
On May 15, at 11.30 a.m., the surface temperature near shore about
a mile east of Lochearnhead was 44°. On May 16, at 10.30 a.m., the
surface temperature at the St. Fillans end of the loch was 44°-l, and
at 1-30 p.m. it was 44°. On May 17, at 5 p.m., the surface temperature
off Dalkenneth over the deepest part of the loch was 43°'8. The range
observed in the temperature of the surface water during those four
days was thus 3°-4, from 430<8 to 47°-2, the range in the air temperature
during the same period being 7°-5, from 400>5 to 48°.

78 BATHYMETRICAL SURVEY OF

A series of temperatures beneath the surface was taken in the deepest
part of the loch on May 17, at 5 p.m., with the following results : —

Surface 43°'8 Fahr.

5 feet 43° -5 „

10 43° -4

20

30

50

100

125

150

200

250

43° -3
43° 2
43° -2
43° -1
42° 3
42° -1
42° -0
41° -5

This series shows a range of 2°'3 between the temperature at the
surface and that at 250 feet, the greatest fall being one of 0°'8 between
100 and 125 feet.

Loch Tummel (see Plate XXIII.). — Loch Tummel is situated amid
beautiful scenery, rock, wood, and water being combined in such a way
as to present pictures of rare loveliness, the crests of Farragon, Meall
Tarruinn Chon, and Schiehallion rising to great heights to the south
and south-west. It contains large trout and a great many pike. Loch
Tummel is two and three-quarter miles in length, with a maximum
breadth of half a mile, the mean breadth being a little over one-third
of a mile, or 13 per cent, of the length. Its waters cover an area of
630 acres, or rather less than one square mile. It drains directly an
area of 62J square miles, but since it receives the outflow from Lochs
Rannoch, Laidon, Ba, &c., its total drainage-area is about 306 square
miles, or 312 times the area of the loch. Nearly 300 soundings were
taken in Loch Tummel, the maximum depth observed being 128 feet, or
4 feet more than the maximum depth recorded by Mr. Grant- Wilson,
who took 123 soundings in 1888. The volume of water contained in the
loch is estimated at 1,316,635,000 cubic feet, and the mean depth at
48 feet, or 37 \ per cent, of the maximum depth. The length of the
loch is 113 times the maximum depth, and 302 times the mean depth.
The floor of Loch Tummel is irregular, falling into three deep basins
separated by two ridges, the maximum depth on the westerly ridge
being 52 feet, and the maximum depth on the easterly ridge being 56
feet. The deepest of the three basins is situated near the west end of the
loch, the maximum depth of 128 feet occupying a central position in this
basin, but a short distance to the south a sounding of 74 feet is recorded
in close proximity to a sounding of 127 feet. The 100-feet contour-line
in this western basin is almost circular and nearly one-third of a mile in
diameter ; about one-fifth of a mile to the east is an isolated sounding
of 102 feet, surrounded by shallower water. The central 100-feet basin
is oblong in outline and nearly half a mile in length, the maximum

THE FRESH- WATER LOCHS OF SCOTLAND.

79

depth of 119 feet having been observed towards the eastern end of the
basin. The eastern basin just falls short of attaining a depth of 100
feet, the maximum observed being 99 feet; the 75-feet contour is
approximately oblong in outline and nearly one-third of a mile in
length. The 50-feet basin is a continuous area stretching from about a
quarter of a mile from the west end to within 100 yards from the east
end of the loch, and is nearly two and a half miles in length.

The area of the lake-floor covered by less than 50 feet of water is
about 352 acres, or 56 per cent, of the entire area of the loch; the area
covered by water between 50 and 100 feet in depth is about 217 acres,

FIG. 23. LOCH TUMMEL.

(Photograph by J. Parsons, B.Sc.)

or 34^ per cent. ; and that covered by more than 100 feet of water is
about 60 acres, or 9J per cent, of the total area of the loch.

Loch Tummel was surveyed 011 April 23 and 24, 1902, the level of
the surface of the water being found, by levelling from Ordnance Survey
bench-mark, to be 454-5 feet above the sea. When levelled by the
surveyors of the Ordnance Survey on June 26, 1860, the surface of the
water was found to be 453'3 feet above sea-level.

Temperature Observations. — The temperature of the surface water of
Loch Tummel at 1.30 p.m. on April 23, 1902, was 43°'2 Fahr. ; at
9.45 a.m. on the next day (April 24) the surface temperature was 45°'0,
and at 1 p.m. in the centre of the loch the surface temperature was

80 BATHYMETRICAL SURVEY OF

43°-5. A series of temperatures was taken below the surface at 1 p.m.
on April 24, 1902, in 102 feet of water, with the following results: —

Surface 43°%5 Fahr.

5 feet 43° v> ,,

10 „ 43° '4 „

20 „ 43° -2 „

50 „ 43°-0 „

70 „ 42°-6 „

100 „ 42°-4 „

showing a gradual decrease of temperature from surface to bottom, the
range of temperature being 10>1 in the 100 feet of water.

Loch Tay (see Plates XXIV. and XXV.).— Loch Tay is one of the
largest of the Scottish fresh-water lochs, unsurpassed in the beauty of
its surroundings, and well known to anglers on account of its salmon
fishings, which are among the best in Scotland. It is also a good trout-
fishing loch, having been much improved within recent years by being
stocked with Loch Leven trout. The scenery around the loch is very
fine — grand and wild towards the south-west end, with the mighty Ben
Lawers rising from its northern shores about half-way down the loch,
becoming more sylvan in character towards the north-east end, a
splendid view presenting itself to the eyes of a spectator from Kenmore
Bridge (see Fig. 24).

Loch Tay is the largest loch in the basin of the river Tay, though
Loch Ericht is a very formidable rival for this distinction, as will be
seen from the following comparison : —

Loch Tay.

Loch Ericht.

Length...

14 '55 miles.

14'5 miles.

Maximum breadth ...

1 -07 miles.

1 -0 mile.

Mean breadth...

070 mile. 0'5 mile.

Superficial area ... | 10'19 square miles.
Maximum depth ... 508 feet.

7 '21 square miles.
512 feet.

Mean depth 199 076 feet. 189 "201 feet.

Volume of water

56,550 million cub. ft.

38,027 million cub. ft.

This comparison shows that the maximum depth observed in Loch
Ericht slightly exceeds that observed in Loch Tay, but in all other
respects Loch Tay has the advantage, though as regards length and
maximum breadth the two lochs are almost identical.

Loch Tay is over 14J miles in length, and over one mile in maximum
breadth, the mean breadth being nearly three-quarters of a mile, or
nearly 5 per cent, of the length. Its waters cover an area of over 6500
acres, or over 10 square miles, and it drains directly an area of about
187J square miles, but since it receives the outflow from Lochs Dochart
and lubhair, its total drainage-area is over 232 square miles, or nearly

THE FRESH- WATER LOCHS OF SCOTLAND. 81

23 times the area of the loch. Nearly 1000 soundings were taken
in Loch Tay, and the maximum depth observed was 508 feet. The
maximum depth recorded by Mr. Grant-Wilson in 1888, when he took
415 soundings in Loch Tay, was 85 fathoms, or 510 feet. The volume
of water contained in the loch is estimated at 56,549,745,000 cubic feet,
or over one-third of a cubic mile, and the mean cTepth at 199 feet, or 39
per cent, of the maximum depth. The length of the loch is 151 times
the maximum depth, and 386 times the mean depth.

Loch. Tay trends in a north-east and south-west direction, being
slightly sinuous in outline, somewhat like the italic letter/, as was noted

FIG. 24. LOCH TAY. FKOM KKNMOUK BRIDGE.

(Photograph by T. N. John»ton, M.B.. C.M., F.R.S.E.)

in the case of Loch lubhair, which flows into it. It is extremely simple
in conformation, the bottom sloping gradually, without any pronounced
irregularities, on all sides down to the deepest part, as is well shown
on the longitudinal and cross sections on the map. The 50-feet basin
approaches to within less than 400 feet from the south-west end and less
than 800 feet from the north-east end, and is 14J miles in length. The
slope of the bottom is thus steeper at the south-west end than at the
north-east end. In the former position a sounding of 65 feet was taken
about 750 feet from shore, giving a gradient of 1 in 11J, and in the
latter position a sounding of 80 feet was taken about 1075 feet from
shore, giving a gradient of 1 in 13J. The 100-feet basin extends from

G

82 BATHYMETRICAL SURVEY OF

about a quarter of a mile from the south-west end to about one-third of
a mile from the north-east end, and is very nearly 14 miles in length.
The 200-feet basin stretches from about 1| miles from the north-east end
to about 2i miles from the south-west end, and is about 11 miles in
length. The main 300-feet basin approaches to within less than two
miles from the north-east end, and is over 7| miles in length; it is
separated, by a slight shoaling of the bottom over an interval of about
a mile, from a small subsidiary 300-feet basin (based upon soundings of
301 and 305 feet), which is over half a mile in length. The 400-feet
basin is over 3J miles in length, lying in the northern half of the loch,
and approaching to about 3| miles from the north-east end. The
deepest part of the loch lies between Skiag on the south-eastern shore
and Cragganruar on the north-western shore, about 5J miles from the
north-east end of the loch, or about 6 miles by road from Kenmore,
where there is a small basin over 500 feet in depth, two soundings of
508 feet being recorded about midway between the two shores.

The area of the lake-floor covered by less than 100 feet of water is
estimated at about 1972 acres (over 3 square miles), or over 30 per cent,
of the total area of the loch ; the area between the 100-feet and 200-feet
contour-lines is about 1532 acres (nearly 2J square miles), or 23J per
cent. ; the area between the 200-feet and 300-feet contours is about
1390 acres (over 2 square miles), or over 21 per cent. ; the area between
the 300-feet and 400-feet contours is about 1017 acres (over 1J square
miles), or 15J per cent. ; the area between the 400-feet and 500-feet
contours is over 600 acres (rather less than one square mile), or over
9 per cent. ; while the area covered by more than 500 feet of water is
about 9 acres, or a small fraction of 1 per cent, of the entire area of the
loch. These gradually decreasing areas between the contour-lines drawn
in at intervals of 100 feet indicate that the average slope of the bottom
becomes steeper and steeper on proceeding from the shore out into deep
water; this is also clearly shown by a comparison of the two shallow
zones on both sides of the 50-feet contour-line, the area between the
shore and the 50-feet line being about 1161 acres, while the area
between the 50-feet and 100-feet lines is about 811 acres, or respectively
about 18 and 12J per cent, of the total area of the loch. The slope of
the bottom of the loch is shown on the natural scale and exaggerated
five times on the longitudinal and cross sections on the map.

Loch Tay was surveyed on April 29 to May 7, 1902, and the level
of the surface of the water was determined by levelling from bench-
marks as being 349-1 feet above the sea. The officers of the Ordnance
Survey found the level to be 347-9 feet above the sea on August 12,
1899.

Temperature Observations. — Many surface temperatures were taken
during the progress of the survey from April 29 to May 7, 1902, the
readings varying from 41°-8 Fahr. to 47°-5— a range of 5°-7. The higher

THE FRESH-WATER LOCHS OF SCOTLAND.

83

readings, as a rule, were taken near shore, and the lower readings
towards the centre of the loch over deep water. When visited on May
28, 1903, the surface temperature at noon, about a mile from Kenmore,
was found to be 49°'3.

Two serial temperatures were taken beneath the surface in May,
1902, and one series in May, 1903, as given in the following table : —

Depth (feet).

May 1, 1902.
Off Ardeonaig.

May 6, 1902.
Between Lawers and
Fearnan, 4 p.m.

May 28, 1903.
1 mile west of Kenmore,
noon.

0

43-8

42-0

49-3

3

47-0

5

43 !2

42<)

44-5

10

43-2

41-9

440

20

420

41-9

25

43-1

30

41 *

41-8

50

41-7

41-8

42-9

100

41-2

41-7

42-5

150

41O

200

40-8

41 ^

•_>.-* i

40-5

...

300

40-3

41-0

350

...

41-0

It will be seen that on May 1, 1902, the temperature of the water down
to 30 feet was higher than on May 6, 1902, while from 50 feet down-
wards it was lower. The range of temperature between the surface and
a depth of 300 feet on May 1 was 3°-5 (from 40°-3 to 43°-8), while on
May 6 it was only 1° (from 41° to 42°). On May 28, 1903, the tem-
perature of the water was found to be considerably higher from the
surface down to a depth of 100 feet than was observed in the previous
May, the range of temperature in the upper 100 feet of water being 60-8
(from 42°-5 to 49°-3).

Loch Derculich (see Plate XXVI.). — Loch Derculich, situated in
Strathtay amid beautiful scenery, affords good fishing, but is strictly
preserved; it flows by the Derculich burn into the river Tay to the
north-east of Aberfeldy. It is surrounded by low rounded hills covered
with heather, and there are few conspicuous boulders, but many small
ones. To the north are high, steep hills (Farragon, &c.), with grey
screes. The knoll forming the point at the boathouse on the south-
eastern shore is high and planted with trees. The burn flows out of the
loch by an artificial dam and sluice, which was open on the date of the
survey, and the water in the loch was very low, a long gravelly point
(not shown on the Ordnance Survey chart) appearing, and the island to
the north was nearly, while the island to the south was quite, joined
to the shore. Loch Derculich (pronounced Der'clich) is over half a mile

84 BATHYMETRICAL SURVEY OF

in length from north to south, and also in maximum breadth from east
to west, the mean breadth being over a quarter of a mile, or 45 per cent.
of the length. Its waters cover an area of over 100 acres, or about
one-sixth of a square mile, and it drains an area ten times greater —
over 1J square miles. About 60 soundings were taken, the maximum
depth observed being 70 feet. The volume of water is estimated at
108,333,000 cubic feet, and the mean depth at nearly 25 feet, or 35 per
cent, of the maximum depth. The length of the loch is 44 times the
maximum depth and 126 times the mean depth. A ridge crosses the
loch at the narrowest part near the middle, the greatest depth on which
is 34 feet. On both sides of this ridge the water deepens, the maximum
depth in the southern basin being 45 feet, while the main deep basin
lies to the north of the ridge, the maximum depth of the loch (70 feet)
having been found less than a quarter of a mile from the north-eastern
angle of the loch, where there is a small 50-feet basin about one-tenth of
a mile in length; a short distance to the north-east is an isolated
sounding of 50 feet, comparatively close to the north-east shore,
separated from the 50-feet basin by a sounding of 38 feet. The 25-feet
basin is a continuous area half a mile in length and over a quarter of a
mile in breadth. The area of the lake-floor covered by less than 25 feet
of water is about 53 J acres; that covered by water between 25 and 50
feet in depth is about 44| acres; while that covered by more than 50
feet of water is about 2J acres. Loch Derculich was surveyed on May
27, 1903 ; the elevation above the sea could not be determined.

Temperature Observations. — A series of temperatures was taken
in the deepest part of the loch at 8 p.m. on May 27, 1903, with the
following results : —

Surface

55° -0 Fahr

10 feet

51° -0 „

15 ,,

49°'0 ,,

25 „

47°7 ,,

50 ,,

47° -1 ,,

65 „

47°'0 „

70 „

47° -0 „

The range of temperature from surface to bottom was 8°'0, there being
a fall of 4°-0 between the surface and a depth of 10 feet, and a further
fall of 3°-3 between 10 and 25 feet. A comparison of these temperatures
with those taken in Lochs Daimh and Giorra on the previous day shows
that the water in Loch Derculich was much warmer from surface to
bottom than in the two lochs referred to : at the surface the temperature
was about 5°, and at 10 feet 3° to 4° higher ; at the bottom it was 4°
higher than at the bottom of Loch Daimh, and 1° higher than at the
bottom of Loch Giorra at a much less depth.

.

Loch Scoly (see Plate XXVI.).— Loch Scoly, a small hill loch in

THE FRESH- WATER LOCHS OF SCOTLAND. 85

Strathtay, lying to the north-east of Loch Kennard and west of Loch
Skiach, and flowing by the Balnaguard burn into the river Tay shortly
before its junction with the river Tummel, is over a quarter of a mile in
length, with a maximum breadth of about one-eighth of a mile, the
mean breadth being about one-sixteenth of a mile or 21 per cent, of the
length. Its waters cover an area of about 11 J acres, and it drains an
area 13 times greater, or about a quarter of a square mile. Twenty-
five soundings were taken, the maximum depth observed being 12 feet.
The volume of water is estimated at 2,888,000 cubic feet, and the mean
depth at nearly 5| feet, or 48 per cent, of the maximum depth. The
length of the loch is 123 times the maximum depth, and 258 times
the mean depth. The loch forms a simple basin; the deeper water is
found towards the southern end, the three soundings exceeding 10 feet
being centrally placed in the southern half of the loch. Only three
soundings were taken under 5 feet close to the shore, so that the slope
of the bottom is on the whole moderately steep. The area of the lake-
floor covered by less than 10 feet of water is over 10 acres, or 88
per cent, of the total area of the loch, and only a small proportion of this
area is covered by less than 5 feet of water. Loch Scoly was surveyed
on May 29, 1903. The temperature of the surface water was 63°-0
Fahr., and a reading at 5 feet gave the same result, while a reading at
10 feet gave 560>0 — a fall of 7°'0 in the temperature of the water at
10 feet as compared with that at 5 feet.

Loch Ordie (see Plate XXVI.). — Loch Ordie is a very pretty loch
situated amid grouse-moors to the east of the river Tay, and surrounded
by wooded hills; it is a good trouting loch, but strictly preserved. It
trends in an east-and-west direction, being widest towards the west end
and narrowing somewhat towards the east end. It is nearly two-thirds
of a mile in length, and nearly half a mile in maximum breadth, the
mean breadth being over a quarter of a mile, or 44 per cent, of the
length. Its waters cover an area of about 116 acres, or nearly one-fifth
of a square mile, and it drains an area nearly 24 times greater — over
4£ square miles. Sixty-five soundings were taken, the maximum depth
observed being 69 feet. The volume of water is estimated at 133,110,000
cubic feet, and the mean depth at 26J feet, or 38 per cent, of the
maximum depth. The length of the loch is 49 times the maximum
depth, and 128 times the mean depth. Loch Ordie is extremely simple
in conformation, the bottom sinking gradually on all sides down to the
greatest depth, which is approximately centrally placed, though rather
nearer the west than the east end. The 25-feet basin is about two-fifths
of a mile in length and over a quarter of a mile in maximum width,
while the 50-feet basin is about a quarter of a mile in length and one-
seventh of a mile in maximum width. The area of the lake-floor
covered by less than 25 feet of water is about 66 acres, or 57 per cent.

86 BATHYMETRICAL SURVEY OF

of the total area of the loch; that covered by water between 25 and
50 feet in depth is about 34 acres, or 29 per cent. ; while that covered by
over 50 feet of water is about 16 acres, or 14 per cent, of the entire area
of the loch. Loch Ordie was surveyed on June 3, 1903, and the level of
the surface of the water was determined by levelling from bench-mark
as being 946'3 feet above the sea.

Temperature Observations. — Serial temperatures taken in the deepest
part of the loch gave the following results : —

Surface 57°'6 Fahr.

10 feet 55°'3

15 ,, 49°'5

25 ,, 47°'l

50 „ 45° 7

68 „ 45°-4

The range of temperature from surface to bottom was 120>2, there being
a fall of 5°-8 between 10 and 15 feet.

Loch na Craige (see Plate XXVI.). — Loch na Craige (or na-Craig),
one of the best trout lochs in the district, is situated in Strathtay about
3 miles to the south-east of Aberfeldy, and flows into the river Bran by
the Cochill burn, which also receives the outflow from Loch Hoil. It is
surrounded by low, heather-clad hills covered with stony debris. It is
nearly half a mile in length, nearly one-eighth of a mile in maximum
breadth, the mean breadth being about one-twelfth of a mile, or 16 per
cent, of the length. The waters of the loch cover an area of about 24
acres, and it drains an area fourteen times greater, or more than half a
square mile. Nearly 30 soundings were taken, the maximum depth
observed being 13 feet. The volume of water is estimated at 7,871,000
cubic feet, and the mean depth at nearly 1\ feet, or 57 per cent, of the
maximum depth. The length of the loch is 195 times the maximum
depth, and 342 times the mean depth. Loch na Craige is a long,
narrow depression trending in a north- west and south-east direction,
or nearly north and south. It forms a simple basin, the deep water
running along the centre of the loch, the area covered by more than 10
feet of water being over one-third of a mile in length, but it is rather
curious to note that the maximum depth of 13 feet was found at the
extreme southern end of the 10-feet basin and comparatively very close
to the southern shore. The slope of the bottom is thus pretty steep
here, and in other places the slope is steep ; for instance, two soundings
of 11 feet were taken about 60 feet from shore, one off the western and
one off the eastern shore, giving a slope of 1 in 5 -5. About 63 per cent,
of the lake-floor, or about 15J acres, is covered by less than 10 feet of
water. Loch na Craige was surveyed on May 29, 1903; the elevation
of the surface of the water was determined by levelling from bench-
mark as being 1297-3 feet above the sea.

THE FRESH- WATER LOCHS OF SCOTLAND. 87

Temperature Observations. — Temperatures were taken in the deepest
part of the loch, with the following results : —

Surface ..................... l30°-OFahr.

.5 feet ... ............. . ... 60°-0 „

Loch Kennard (see Plate XXVI.). — Loch Kennard, a good fishing
loch abounding with small trout, is situated in Strathtay, and flows
into the river Bran by the Ballinloan burn. Its shores are nearly all
wooded, and where not planted with trees the low hills are covered
with heather. It is peculiar in outline, somewhat resembling that of a
young mushroom, the stem pointing west and the apex of the crown
pointing north-east. It is over two-thirds of a mile in length, and over
one-third of a mile in maximum breadth, the mean breadth being over
one-sixth of a mile, or 26 per cent, of the length. Its waters cover an
area of about 77 acres, or nearly one-eighth of a square mile, and it
drains an area seven times greater, or nearly nine-tenths of a square
mile. Nearly 50 soundings were taken, the maximum depth observed
being 72 feet. The volume of water is estimated at 108,439,000 cubic
feet, and the mean depth at 32J feet, or 45 per cent, of the maximum
depth. The length of the loch is 50 times the maximum depth and 111
times the mean depth Loch Kennard forms a simple basin, with here
an'd there minor undulations of the bottom. The deepest water (72 feet)
is found in the centre of the widest part of the loch, to the east of the
constriction in its outline ; in the middle of this constriction a depth of
70 feet was found, but immediately to the west the bottom rises to 50
feet beneath the surface, and falls again further west to a depth of
63 feet. The 25-feet basin is half a mile in length and over a quarter
of a mile in maximum width, while the 50-feet basin is over one-third
of a mile in length. The area of the lake-floor covered by less than
25 feet of water is nearly 30 acres, or 38 per cent, of the entire area of
the loch; that covered by water between 25 and 50 feet in depth is
about 33 acres, or 43 per cent. ; while that covered by more than 50
feet of water is over 14 acres, or 19 per cent, of the total area of the
loch. These figures show that the average slope is steeper between the
shore and the 25-feet contour-line than between the 25-feet and 50-feet
contours. Loch Kennard was surveyed on May 29, 1903 ; the elevation
of the surface of the water above the sea was not determined.

Temperature Observations. — Temperatures were taken in the deepest
part of the loch, with the following results : —

Surface ..................... 56°'7 Fahr.

ofeet .................... 51°-0 ,,

10 „ ................... 48°-3 „

2.-> ,, ..................... 46°'0 „

.->n ,, .................... 45°-5 „

72 . 45° 3

88 BATHYMETRICAL SURVEY OF

The range in the temperature of the water from surface to bottom was
thus ll°-4, the fall of temperature between the surface and a depth of
5 feet amounting to 5°-7, that between 5 and 10 feet amounting to 20>7,
and that between 10 and 25 feet to 2°-3. A comparison of these
temperatures with those taken in Loch Derculich two days previously
shows that the temperature of the whole body of water in Loch Kennard
was lower than that in Loch Derculich (except at the surface — which
may be due to the fact that the observations in Loch Kennard were
made in the early afternoon, while those in Loch Derculich were taken
in the late evening).

Loch Skiach (see Plate XXVI.). — Loch Skiach, situated in Strath-
tay, containing large trout as well as pike, flows into Little Loch Skiach
(which was not sounded) by a short burn with a slight fall, and thence
by the Pitleoch burn into the Ballinloan burn shortly before it joins
the river Bran. It is surrounded by low, rounded, heather-clad hills
with scattered boulders, and the shores are of clean shingle with
boulders. It is very irregular in outline, the longer axis being nearly
north and south, and the bottom is also irregular. It is over three-
quarters of a mile in length, and nearly half a mile in maximum
breadth, the mean breadth being nearly one-fifth of a mile, or 25 per
cent, of the length. Its waters cover an area of about 98 acres, or
over one-seventh of a square mile, and it drains an area six times
greater — an area of nearly one square mile. Eighty-five soundings were
taken in Loch Skiach, the maximum depth observed being 55 feet.
The volume of water is estimated at 77,185,000 cubic feet, and the mean
depth at 18 feet, or 33 per cent, of the maximum depth. The length of
the loch is 75 times the maximum depth, and 228 times the mean depth.
Near the middle a ridge crosses the loch from south-east to north-west,
on which the depth is less than 20 feet; this ridge separates the two
deep basins, of which the southerly one is the deeper, the maximum
depth of 55 feet having been recorded about a quarter of a mile from
the southern end of the loch, while the greatest depth recorded in the
northern basin was 45 feet in two places. The two 25-feet basins are
each under a quarter of a mile in length. Near the middle of the loch
the slope of the bottom is very steep in places — for instance, a sounding
of 33 feet was taken off the eastern shore at a distance of about 100 feet,
giving a slope of 1 in 3, and a sounding of 26 feet about the same
distance off the western shore gives a slope of 1 in 3 -8. The area of the
lake-floor covered by less than 25 feet of water is about 77 acres, or 79
per cent, of the total area of the loch; that covered by water between
25 and 50 feet in depth is about 20 acres, or 20 per cent. ; while that
covered by more than 50 feet of water is only about 1J acres, or 1 pel-
cent . Loch Skiach was surveyed on June 12, 1903, and the level of the
surface of the water was determined by levelling from bench-mark as
being 1385-7 feet above the sea.

THE FRESH- WATER LOCHS OF SCOTLAND. 89

Temperature Observations. — The temperature of the surface water on
commencing the survey at 9 a.m. on June 12, 1903, was 59°-0 Fahr.
Later in the day serial temperatures were taken in the deepest part
of the loch, with the following results: —

Surface 600i)Fahr.

10 feet 59° -0 ,,

15 ,, 55°-3 ,,

20 „ 49°'2 „

»' „ 49°'0 >.

45 ,, 48°-0 „

55 ,, ... ... ... ... ... ... ... 47°'5 ,,

The range in the temperature of the water from surface to bottom was
thus 120>5 ; between the surface and a depth of 10 feet the fall was only
1°, but between the depths pf 10 and 20 feet the fall of temperature
amounted to nearly 10° — 3°-7 between 10 and 15 feet, and 6°'l between
15 and 20 feet. These readings are all higher than those taken in Lochs
Kennard and Derculich about a fortnight earlier in the season.

Loch Broom (see Plate XXVII.). — Loch Broom, a fine trout loch,
but strictly preserved, lies to the east of the river Tummel, into which
it flows by the Lochbroom burn to the north of Ballinluig, before the
river Tummel joins the river Tay. It is nearly three-quarters of a mile
in length, and over one-third of a mile in maximum breadth, the mean
breadth being nearly one-fifth of a mile. Its waters cover an area of
about 86 acres, or over one-eighth of a square mile, and it drains an
area of 3J square miles — an area 26 times greater than the area of the
loch. Over 60 soundings were taken in Loch Broom, the maximum
depth observed being 9 feet. The volume of water contained in the loch
is estimated at 18,813,000 cubic feet, and the mean depth at 5 feet, or
56 per cent, of the maximum depth. The length of the loch is 422 times
the maximum depth, and 757 times the mean depth.

Loch Broom is very shallow, being simply a large bog-hole, or
depression in the moorland, with shores of yellow sandy debris covered
by peat, and all heather clad. The outflow is over a dam about 5 feet
high, so that the greater part of the loch must be artificial. Where the
depth is less than 5 feet the bog-bean is everywhere seen, and there are
numerous islets — some of peat, others chiefly of bog-bean — on several of
which gulls nest. The deeper water (over 5 feet) lies to the east and
north of the islets, the maximum depth of 9 feet having been observed
in several places towards the eastern shore ; along the western shore and
around the islets the bottom is covered by less than 5 feet of water, but
at the outflow, where the waters of the loch pass into Lochbroom burn,
two soundings of 5 feet were taken. The area of the lake-floor covered
by less than 5 feet of water is about 38 acres, or 44 per cent, of the
entire area of the loch, while that covered by more than 5 feet of water

90 BATHYMETRICAL SURVEY OF

is about 48 acres, or 56 per cent. Loch Broom was surveyed on June
11, 1903, but the elevation above the sea could not be determined.
Drift-marks were observed 3 feet above the level of the water on the
date surveyed.

The temperature of the surface water on commencing the survey at
noon on June 11, 1903, was 60°'0 Fahr., and two readings in open
water — one at the surface and one at a depth of 8 feet — gave in each
case 60°-8.

Loch Essan (see Plate XXVII.). — Loch Essan (or Easain), a hill loch
lying to the north of Loch Dochart, containing dark-coloured trout of
rare quality, but strictly preserved, flows by the Allt Essan into the
river Dochart after it leaves Loch lubhair. It is nearly half a mile in
length, and over one-fifth of a mile in maximum breadth, the mean
breadth being about one-ninth of a mile. Its waters cover an area of
about 32 acres, and it drains an area of over 1J square miles — an area
32 times greater than the area of the loch. Over 40 soundings were
taken in Loch Essan, the maximum depth observed being 18 feet. The
volume of water is estimated at 9,664,000 cubic feet, and the mean
depth at nearly 7 feet, or 38 per cent, of the maximum depth. The
length of the loch is 135 times the maximum depth, and 356 times the
mean depth. The loch trends in an east and west direction, and is very
irregular in outline. The bottom is also irregular, forming three small
basins with depths exceeding 10 feet, the westernmost being the deepest,
the maximum depth of 18 feet having been observed about one-sixth of a
mile from the west end of the loch. To the east of this western deep
basin, and near the centre of the loch, lies a heap of stones around
which soundings of 6 feet were taken. A little farther to the east lies
the central 10-feet basin, based on a sounding of 11 feet. To the east
of the central basin there is a constriction in the outline of the loch in
which soundings of 7 and 8 feet were taken, and on approaching the east
end the loch widens out, and the bottom sinks to form the third (eastern)
10-feet basin, the maximum depth in which is 16 feet. To the south of
this eastern basin is a small island, the passage between the island and
the shore being obstructed by weeds, and weeds are also abundant along
the northern shore. The area of the lake-floor covered by less than 10
feet of water is about 26 acres, or 81 per cent, of the total area of the
loch, while that covered by more than 10 feet of water is about 6 acres,
or 19 per cent. Loch Essan was surveyed on June 16, 1903, the
elevation of the surface of the water being estimated at about 1440 feet
above sea-level.

Lochan Breaclaich (see Plate XXVII.). — Lochan Breaclaich (or
Loch-an-Breacklaich), a hill loch containing fine trout, flows into Loch
Tay near its south-west end by the Allt na Breaclaich. It is peculiar

THE FRESH- WATER LOCHS OF SCOTLAND. 91

in outline, somewhat resembling the capital letter Y, a promontory of
land projecting into the loch from the eastern shore opposite the inlet
on the western shore which leads to the outflow. The length of the loch
from north-east to south-west in a straight line is about half a mile, but
a line following the axis of deep water would be considerably over half
a mile in length. The maximum breadth is about one-third of a mile,
and the mean breadth about one-seventh of a mile. Its waters cover
an area of about 43 acres, and it drains an area twenty times greater,
or about 1J square miles. About 60 soundings were taken in Lochan
Breaclaich, the maximum depth observed being 41 feet. The volume of
water is estimated at 26,619,000 cubic feet, and the mean depth at 14
feet, or 34 per cent, of the maximum depth. The length of the loch is
64 times the maximum depth, and 187 times the mean depth. The
bottom of the loch is fairly regular, sinking, to the north and south of
the promontory referred to, into two basins with depths exceeding 25
feet, occupying the arms, as it were, of the letter Y, while the shank of
the letter, leading to the outflow, is occupied by shallower water. Of
the two deep basins the northern one is the larger and deeper, the
maximum depth of 41 feet having been found approximately in the
centre of this basin, but towards the north-western shore, while the
southern basin is based upon soundings of 32 and 26 feet. The 10-feet
basin is a continuous area extending from close to the north-eastern end
to near the south-western end, and occupying the greater portion of the
loch. The area of the lake-floor covered by less than 10 feet of water is
over 19 acres, or 45 per cent, of the total area of the loch, while that
covered by more than 10 feet of water is nearly 24 acres, or 55 per cent.
Lochan Breaclaich was surveyed on June 16, 1903, but the elevation of
its surface above the sea could not be determined.

Temperature Observations. — The temperature of the surface water
on commencing the survey at 2 p.m. on June 16, 1903, was 570-0 Fahr.
Serial temperatures taken in the deepest part of the loch gave the
following results : —

Surface

57° -5 Fahr

5 feet

57°'5 ,

10 „

57C'4

t

15 „

51c-2

.

20 ,

49° -3

40 ,

48° O

i

It will be observed that the range of temperature from surface to
bottom amounted to 9°-5, and that the fall of temperature between the
depths of 10 and 15 feet amounted to 6°-2.

Lochan na Lairige (see Plate XXVII.). — Lochan na Lairige lies
to the west of Ben Lawers and flows into Loch Tay by the Allt a'
Mhoirneas, which enters the loch nearly opposite the entrance of the

92 BATHYMETRICAL SURVEY OF

Allt na Breaclaich. It trends in a north and south direction, and is
extremely simple in outline and conformation ; it is oblong in outline,
and of nearly uniform width throughout. It is nearly three-quarters
of a mile in length, and over one-eighth of a mile in maximum breadth,
the mean breadth being one-tenth of a mile, or 14 per cent, of the
length. Its waters cover an area of about 47 J acres, and it drains an
area 16 times greater, or about 1J square miles. Over 40 soundings
were taken, the maximum depth observed being 39 feet. The volume of
water is estimated at 22,682,000 cubic feet, and the mean depth at 11
feet, or 28 per cent, of the maximum depth. The length of the loch is
99 times the maximum depth, and 350 times the mean depth. The
northern portion of the loch is shallow, and water deepening gradually
on proceeding southwards until the maximum depth is encountered
about one-eighth of a mile from the southern end, thence the water
shallows rapidly towards the south end. The 10-feet basin is about half
a mile in length, extending from near the south end to within one-sixth
of a mile from the north end. The 2 5 -feet basin is contained in the
southern half of the loch, and is about a quarter of a mile in length.
The area of the lake-floor covered by less than 10 feet of water is over
29 acres, or 62 per cent, of the entire 'area of the loch, while that covered
by more than 10 feet of water is over 18 acres, or 38 per cent., of which
8 per cent, exceeds 25 feet in depth. Lochan na Lairige was surveyed
on June 16, 1903 ; the surface of the water was estimated at about 1595
feet above the level of the sea.

Lochs Daimh and Giorra. — Lochs Daimh and Giorra, situated in the
wilds of Glenlyon, amid grand and mountainous scenery, are good
trouting lochs, but strictly preserved. Loch Daimh flows into Loch
Giorra by a short river, and the outflow from both lochs is carried into
the river Lyon by the Allt Conait. To the south, on the flanks of
Stuchd an Lochain, lies the small Lochan nan Cat, at an elevation of
over 2000 feet above the sea, which flows into the river between Lochs
Daimh and Giorra. It being reported that this little lochan was frozen
over a few days before the date of the survey of Lochs Daimh and
Giorra, it was visited in the hope of taking soundings through holes in
the ice, but the ice had disappeared. It was apparently shallow all
round the shore, except where there are screes from the cliffs, and, if
at all deep, it must be over a very limited area. The temperature of
the water was 53°-0 Fahr., while a reading taken close under the crags
beside the snow gave 49°- 8.

Loch Daimh (see Plate XXVII.). — Loch Daimh (or Damh) trends
in an east-and-west direction, being widest and deepest towards the west
end, narrowing and shallowing towards the east end. It is nearly a
mile in length, and nearly one-third of a mile in maximum breadth,
the mean breadth being nearly one-fifth of a mile, or 19 per cent, of

THE FRESH- WATER LOCHS OF SCOTLAND. 93

the length. Its waters cover an area of about 111 acres, or over one-
sixth of a square mile, and it drains an area nearly 30 times greater,
or over 5 square miles. Nearly 60 soundings were taken, the maximum
depth observed being 95 feet. The volume of water is estimated at
189,623,000 cubic feet, and the mean depth at 39 feet, or 41 per cent,
of the maximum depth. The length of the loch is 53 times the maximum
depth and 130 times the mean depth. The loch is of simple conforma-
tion, and, on the whole, comparatively deep, only half a dozen soundings
under 10 feet being recorded close to the shore. Off the northern shore,
towards the west end, the slope of the bottom is very steep, soundings
of 31 feet and 44 feet having been taken about 80 and 100 feet from the
shore respectively; this is equal to a slope of 1 in 2-3 to 2-6. The
eastern end, and south-eastern portion of the loch around the island, are
comparatively shallow. The 25-feet basin is about three-quarters of a
mile in length, stretching from quite close to the west end to within
one-sixth of a mile from the east end. The 50-feet basin is nearly half
a mile in length, and the 75-feet basin, occupying the western half of
the loch, is over one-third of a mile in length. The maximum depth
of 95 feet was observed in two places approximately near the centre of
the wide western portion of the loch. The area of the lake-floor
covered by less than 25 feet of water is about 50J acres, or over 45 per
cent, of the total area of the loch ; that covered by water between 25
and 50 feet in depth is about 21J acres, or over 19 per cent.; that
covered by water between 50 and 75 feet in depth is about 19 acres, or
17 per cent. ; and that covered by more than 75 feet of water is about
20J acres, or over 18 per cent, of the entire area of the loch. The flat-
bottomed character of the deep western portion of the loch is well
brought out by a comparison of the last two percentages, while the high
percentage of the bottom covered by less than 25 feet of water is due to
the comparatively large shallow area in the south-eastern and eastern
part of the loch. Loch Daimh was surveyed on May 26, 1903, but the
level of the surface of the water above the sea could not be determined.
Temperature Observations. — The temperature of the surface water
on commencing the survey at 9.30 a.m. on May 26, 1903, was 51°*0
Fahr., and a series of temperatures taken in the deepest part of the
loch gave the following results : —

Surface 50° -3 Fahr.

10 feet 47°-0 „

25 „ 44°-0 „

50 „ 43°'5 „

90 ,, 43°-0 „

The range in the temperature of the water from surface to bottom was
thus 7°'3. The fall of temperature from the surface to a depth of
10 feet amounted to 3°-3, and that between the depths of 10 and 25 feet
amounted to 3°-0, and below 25 feet the fall amounted to 1°-0.

94 BATHYMETRICAL SURVEY OF

Loch Giorra (see Plate XXVII.). — Loch Giorra (or Girre) trends
almost east and west ; there is a slight bend near the middle of the loch,
the eastern half trending north-west and south-east. It is over four-
fifths of a mile in length, with a maximum breadth of over a quarter
of a mile, the mean treadth being about one-sixth of a mile, or 20 per
cent, of the length. Its waters cover an area of about 88J acres, or
less than one-seventh of a square mile, and^ it drains directly an area of
over 5J square miles, but, since it receives the outflow from Loch
Daimh, its total drainage area is over lOf square miles — an area 78
times greater than the area of the loch. Fifty-five soundings were taken
in Loch Giorra, the maximum depth observed being 49 feet. The
volume of water is estimated at 83,686,000 cubic feet, and the mean
depth at nearly 22 feet, or 44 per cent, of the maximum depth. The
length of the loch is 88 times the maximum depth, and 200 times the
mean depth.

The floor of Loch Giorra is rather irregular. The deepest part is in
the western half, the maximum depth of 49 feet having been observed
about one-sixth of a mile from the west end. The 2 5 -feet basin in this
part of the loch is about two-fifths of a mile in length, and towards the
east end there is a second 25-feet basin about one-fifth of a mile in
length, in which the maximum depth is 40 feet. These two basins are
separated by a remarkable rise of the bottom, on which depths of 15
and 18 feet were recorded, surrounded 011 all sides by deeper water. The
area of the lake-floor covered by less than 20 feet of water is nearly
43 acres, or over 48 per cent, of the total area of the loch ; that covered
by water between 20 and 40 feet in depth is nearly 38 acres, or about
42£ per cent. ; while that covered by more than 40 feet of water is
over 8 acres, or over 9 per cent. Loch Giorra was surveyed on the same
day as Loch Daimh (May 26, 1903) ; its elevation above the sea could
not be determined.

Temperature Observations. — A series of temperatures taken in the
deepest part of the loch gave the following results : —

Surface ... 50°'OFahr.

10 feet 48°-0 ,,

25 ,, 46°-8 „

45 ,, 40° -o ,,

A comparison of these temperatures with those taken in Loch Daimh
later in the day shows that, while the surface temperature in each loch
was nearly identical, the temperature of the water beneath the surface
was lower in the deeper loch : thus at 10 feet the temperature in Loch
Daimh was 1°-0 lower than in Loch Giorra, at 25 feet it was 2°-8 lower,
and at 50 feet it was 2°'5 lower than at 45 feet in Loch Giorra.

Loch Bhac (see Plate XXVIII,).— Loch Bhac (Bhaic, or Vach) lies
to the north of Loch Tummel, and flows by the Allt Bhaic into the river

THE FRESH- WATER LOCHS OF SCOTLAND. 95

Garry between Struan and Blair Atholl. It contains fine trout, but the
fishing is strictly preserved. It is surrounded by low, heather-clad hills,
which slope gradually up from the shores of the loch. There are few
weeds, and the bottom is sandy, or (in parts) gravelly. Loch Bhac
trends in a north-east and south-west direction, and is extremely simple
in outline and in conformation. It is over one-third of a mile in
length, and one-sixth of a mile in maximum breadth, the mean breadth
being over one-eighth of a mile, or 33 per cent, of the length. Its
waters cover an area of about 31 acres, or one-twentieth of a square
mile, and it drains an area thirty-six times greater, or nearly 2 square
miles. About 30 soundings were taken, the maximum depth observed
being 42 feet. The volume of water contained in the loch is estimated
at 22,104,000 cubic feet, and the mean depth at 16J feet, or 39 per cent,
of the maximum depth. The length of the loch is 48 times the maximum
depth, and 122 times the mean depth. Loch Bhac forms a simple basin,
the bottom sloping gradually down on all sides to the deepest part,
which is approximately centrally placed, but rather nearer to the
southern end and to the eastern shore, where the slope of the bottom is
steeper than at the northern end and off the western shore. The area
of the lake-floor covered by less than 10 feet of water is about 16 acres,
or 51 per cent, of the entire area of the loch; that covered by water
between 10 and 25 feet in depth is about 8 acres, or 25 per cent. ; and
that covered by more than 25 feet of water is about 7 acres, or 24 per
cent, of the total area of the loch. Loch Bhac was surveyed on July 6,
1903, but the elevation of its surface above the sea could not be deter-
mined from bench-mark, though from a spot-level at the north end of
the loch it is apparently slightly under 1070 feet. The water rises and
falls very little, the range being probably less than 1 foot. On 'com-
mencing the survey at 6.15 p.m., the temperature of the surface water
was 53°-0 Fahr., and in the centre of the loch a little later readings at
the surface, at 25 feet, and at 40 feet gave identical results, 45°'0.

Loch Con (see Plate XXVIII.).— Loch Con (Chon, or Choin) lies
to the east of Loch Garry, and flows by the Allt Choin into Erochy
water, which joins the river Garry at Struan. It was formerly a good
trout loch, but now contains many pike, which are supposed to have
been maliciously introduced. Its gradually sloping shores are heather-
clad, with few large boulders.* There are trees on the islands and on the
promontory at the west end. The outflowing burn goes through a large
flat mass of moraine debris, which extends far down the burn. The loch
trends in an east and west direction, and is extremely irregular in
outline, being almost divided into two portions by a narrow constriction
near the middle. It is nearly a mile in length, and over a quarter of
a mile in maximum breadth, the mean breadth being over one-tenth of
a mile, or 11 J per cent, of the length. Its waters cover an area of about

96 BATHYMETRICAL SURVEY OF

65 acres, or one-tenth of a square mile, and it drains an area of over 3|
square miles — an area 37 times greater than the area of the loch. Over
60 soundings were taken, the maximum depth observed being 9 feet.
The volume of water contained in the loch is estimated at 9,818,000
cubic feet, and the mean depth at 3J feet, or 39 per cent, of the
maximum depth. The length of the loch is 550 times the maximum
depth and 1430 times the mean depth. Loch Con is very shallow, and
the central constriction cuts it into two basins, the deepest water being
found near the east end, where two soundings of 9 feet were taken,
while a sounding of 8 feet was taken in the basin to the north-west of
the constriction. The area of the lake-floor covered by less than 5 feet
of water is about 51 acres, or 78 per cent, of the total area of the loch.
Loch Con was surveyed on July 4, 1903, but the level above the sea
could not be determined with certainty because of the disparity between
the spot-levels around the loch. The loch was about its lowest on the
date of the survey, and drift-marks were observed about 3 feet above the
water. The temperature of the surface water on commencing the survey
at 3 p.m. was 54°-3 Fahr., and at 5 p.m. readings at the surface and at
a depth of 8 feet both gave 550<0.

Loch Tilt (see Plate XXVIII.). — Loch Tilt, at the head of the glen
of that name, consists in reality of two lochs, a broad burn flowing
from the larger (northern) loch to the smaller loch, which is about one
foot lower and full of weeds. The larger loch is nearly half -filled with
weeds (Equisetuni), and the bottom is stony where free from weeds.
The shore is stony, and the loch is surrounded by an almost flat terrace
of peat with stones, with high, rounded, heather-clad hills on the west
side. Loch Tilt is over one-third of a mile in length, and one-fifth of a
mile in maximum breadth, the mean breadth being about one-thirteenth
of a mile, or 22 per cent, of the length. Its waters cover an area of
about 17 acres, and it drains an area twenty-one times greater — an
area of nearly two-thirds of a square mile. Over 20 soundings were
taken, the maximum depth observed being 5 feet. The volume of water
is estimated at 1,839,000 cubic feet, and the mean depth at 2J feet, or
50 per cent, of the maximum depth. Loch Tilt is shallow, the great
majority of the soundings giving depths of 3 and 4 feet, only two
soundings of 2 feet and two soundings of 5 feet being recorded. The
deeper water occurs off the eastern shore, one sounding of 5 feet having
been taken about 60 feet from that shore, giving a gradient of 1 in 12.
Weeds are abundant off the south-western shore, and in the northern
angle of the loch, where there are many large stones in the water.
Loch Tilt was surveyed on July 9, 1903, and the level of the surface
was determined, by levelling from bench-mark, as being 1653*5 feet
above the sea. The water in the loch was low, and drift-marks were

THE FRESH- WATER LOCHS OF SCOTLAND. 97

observed about a foot above the water. The surface temperature at
6 a.m. on the date of the survey was 54°'0.

Loch Moraig (see Plate XXVIII.). — Loch Moraig is an artificial
loch, having been originally an old snipe marsh banked up on the
south ; it flows by a short stream (the Allt Chluain) into the river Garry,
between Blair Atholl and Killiecrankie. It is well stocked with fine
trout, but the fishing is strictly preserved. The surrounding grassy
hills slope gently up from the loch. It trends in a north and south
direction, and is very irregular in outline, being widest at the southern
end, while the northern end is narrow and filled with weeds. It is over
half a mile in length, and over a quarter of a mile in maximum breadth,
the mean breadth being over one-tenth of a mile, or 19 per cent, of the
length. Its waters cover an area of 37 acres, or about one-seventeenth
of a square mile, and it drains an area of over 2 square miles — :an area
thirty-five times greater than the area of the loch. About 40 soundings
were taken, the maximum depth observed being 14 feet. The volume of
water contained in the loch is estimated at 8,921,000 cubic feet, and the
mean depth at 5J feet, or 40 per cent, of the maximum depth. The
length of the loch is 207 times the maximum depth, and 524 times the
mean depth. Loch Moraig is on the whole shallow, only four soundings
exceeding 10 feet being recorded. The deepest water was found at the
southern end near the outflow, the maximum depth of 14 feet being
taken about 60 feet from the southern shore, giving a slope of 1 in 4-3 ;
in this place soundings of 12 and 11 feet were also taken, and in the
northern half of the loch an isolated sounding of 10 feet was recorded.
The area of the lake-floor covered by less than 10 feet of water is about
34 acres, or 92 per cent, of the total area of the loch. Loch Moraig was
surveyed on July 7, 1903, but the elevation above the sea was not
determined; from spot-levels the elevation is probably about 1105 feet.
On the date of the survey the water in the loch was high owing to
recent rains, and the embankment was only a foot or two above the
loch, so that the water could rise only a very little higher.

Temperature Observations. — On commencing the survey at 11 a.m.,
the temperature of the surface water was 52°'0 Fahr. Temperatures
taken in the deepest part of the loch gave the following results : —

Surface 52° -2 Fahr.

8 feet 51°-8 „

14 „ 51°'4 „

Loch Loch (see Plate XXVIII.). — Loch Loch, a good trout loch,
and containing char also, is situated amid wild mountainous scenery,
the hills on both sides being very steep — Ben-y-gloe on the west, and
the precipitous crags of Craig an Loch on the east. Mounds of gravelly
morainic debris occupy the greater part of both shores, forming the

H

98 BATHYMETRICAL SURVEY OF

prominent points. It flows northward by the An Lochain into the river
Tilt, which also receives the waters from Loch Tilt at the head of the
glen. It trends almost due north and south, and is a long narrow loch,
or rather two lochs, there being a very narrow constriction near the
middle dividing it into two portions ; the two lochs were quite distinct
on the date of the survey, with a difference in level of about half a foot.
It is about 1£ miles in length, the southern portion being half a mile,
and the northern portion three-quarters of a mile in length, and about
one-sixth of a mile in maximum breadth, the mean breadth being about
one-tenth of a mile, or 8 per cent, of the length. Its waters cover an
area of about 81 acres, or one-eighth of a square mile, and it drains an
area of about 2 J square miles, an area nineteen times greater than that
of the loch. One hundred soundings were taken, the maximum depth
observed being 81 feet. The volume of water contained in the loch is
estimated at 103,197,000 cubic feet, and the mean depth at over 29 feet,
or 36 per cent, of the maximum depth. The length of the loch is 80
times the maximum depth and 222 times the mean depth. Loch Loch
is peculiar in outline and in conformation. Besides the principal central
constriction, which cuts the loch into two approximate Jialves, there
are three minor constrictions, each accompanied by a shoaling of the
bottom; the most important of these divides the southern half of the
loch into two basins, the more southerly of which has a maximum
depth of 40 feet, while the maximum depth in the second basin is 53
feet. But the greatest depth of the loch is found in the northern half,
about one-fifth of a mile above the central constriction, where the loch
is widest. Here the maximum depth of the loch (81 feet) occurs,
approximately centrally placed, but rather nearer the western than the
eastern shore, and here the slope of the bottom is very steep, a sounding
of 80 feet having been taken about 200 feet off the western shore, giving
a gradient of 1 in 2J, while a sounding of 75 feet was taken about the
same distance off the eastern shore. From the position of maximum
depth the water shoals, and the loch narrows, gradually towards the
northern end. The area of the lake-floor covered by less than 25 feet
of water is about 45 acres, or 55 per cent, of the total area of the loch ;
that covered by water between 25 and 50 feet in depth is about 21
acres, or 26 per cent. ; that covered by water between 50 and 75 feet in
depth is about 10 acres, or 13 per cent., and that covered by more than
75 feet of water is about 5 acres, or 6 per cent, of the entire area of the
loch. Loch Loch was surveyed on July 9, 1903, but the elevation above
the sea could not be determined from bench-mark ; from a spot-level of
1480 feet a short distance up the inflowing burn, the elevation is
probably about 1450 feet. There was no evidence that the loch rises
more than a foot higher than on the date surveyed.

Temperature Observations. — Serial temperatures were taken in the
two halves of the loch : (1) in 40 feet of water near the southern end

THE FRESH-WATER LOCHS OF SCOTLAND.

99

of the loch, and (2) in the deepest part of the northern portion of the
loch, with the following results: —

Southern half.

Northern half.

Surface

0

52-5

0

51-7

5 feet

517

10

51-2

20

.

51-2

25

50-8

40

51-0

50

50-0

75

49-5

These observations indicate a lower temperature throughout the deeper
water in the northern half, as compared with the shallower water in
the southern half of the loch ; the range of temperature in the 40 feet
of water near the southern end amounts to l°-5, as compared with a
range of 2°-2 in the 75 feet of water in the northern portion of the loch.

Loch nan Eun (see Plate XXVIII.). — Loch nan Eun (or na-Nean),
a beautiful but lonely little loch at the head of Glen Taitneach (or the
Pleasant Glen) amid extremely wild scenery, is well stocked with trout
said to be as fine as in any river or loch in Scotland. It flows into the
Shee water at the head of Glenshee. It is surrounded by high hills with
rounded tops, and grey with bare rock or screes. Its shores are peaty,
with many small stones and a few large ones. Loch nan Eun trends in
a north-east and south-west direction, and is very peculiar in outline,
consisting of a subcircular body with a broad arm, in which are two
comparatively large islands, and a short narrow arm extending towards
the north-east. It is nearly half a mile in length, and nearly a quarter
of a mile in maximum breadth, the mean breadth being one-eighth of a
mile, or 28 per cent, of the length. Its waters cover an area of about
37 acres, and it drains an area five times greater, or about one-third of
a square mile. Over 50 soundings were taken, the maximum depth
observed being 50 feet. The volume of water is estimated at about
34,459,000 cubic feet, and the mean depth at 21 J feet, or 43 per cent,
of the maximum depth. The length of the loch is 47 times the maximum
depth, and 110 times the mean depth. Loch nan Eun is comparatively
deep, considering its superficial area, and the soundings reveal some
interesting irregularities of the bottom ; for instance, the line of
soundings taken across the widest and deepest part of the loch from
west to east shows that the bottom sinks gradually off the western shore
to 15, then 46, and then 50 feet (the maximum depth of the loch,
situated about 300 feet from the western shore), thence rising rapidly
to 29 feet, sinking gradually to 32 and 33 feet, then rising sharply
again to 12 feet, and finally sinking to 26 feet at a distance of about 50

100 BATHYMETRICAL SURVEY OF

feet from the eastern shore. The last sounding indicates a very steep
slope in this position, equal to 1 in 1-9, and off the western shore further
north a similar steep gradient is indicated by a sounding of 36 feet
taken about 100 feet from the shore, equal to 1 in 2-8. The soundings
reveal, further, an ill-defined shallow ridge, running in a north and
south direction across the wide portion of the loch, covered by less than
30 feet of water, with deeper water on both sides. The area of the lake-
floor covered by less than 25 feet of water is about 23 acres, or 64 per
cent, of the entire area of the loch. Loch nan Eun was surveyed on
July 2, 1903 ; its elevation above the sea could not be determined from
bench-mark, but, estimated from spot-levels, its elevation must be about
2575 feet. There is evidently very little variation in the level of the
surface of the water, since no drift-mark indicating a higher level could
be seen, and a fall of a few inches would cease to feed the outflowing
burn, which forms a waterfall a few yards from the loch, the top of the
fall being at nearly the same level as the loch.

Temperature Observations. — The temperature of the surface water on
commencing the survey at 10.30 a.m. was 500<0, and a series of tem-
peratures taken at noon in the deepest part of the loch gave the
following results : —

Surface 50°'8 Fahr.

25 feet 50°'5 ,,

45 „ 49°'8 „

Lochs Craiglush, Lowes, Butterstone, Clunie, Drumellie, Rae,
Fingask, White, Black, and the Stormont lochs form a connected series
of lochs all draining into the Lunan burn, which flows into the river
Isla shortly before its junction with the river Tay; they all contain
pike and perch, and trout also are taken in Lochs Craiglush, Lowes, and
Drumellie. The group nearest the source of the Lunan burn consists
of Lochs Craiglush, Lowes, and Butterstone.

Loch of Craiglush (see Plate XXIX.). — The Loch of Craiglush is
situated in Drumbuie wood near Dunkeld, and is almost surrounded by
trees. Its shores are weedy, and where the Lunan burn enters there is
a large grassy flat formed of material brought down by the stream. It
trends in a north-east and south-west direction, and is over half a mile
in length, with a maximum breadth of over a quarter of a mile, the
mean breadth being nearly one-fifth of a mile, or 32 per cent, of the
length. Its waters cover an area of about 70 acres, or over one-tenth
of a square mile, and it drains an area of about 5| square miles — an
area 52 times greater than the area of the loch. Over 50 soundings were
taken, the maximum depth observed being 44 feet. The volume of
water contained in the loch is estimated at 49,079,000 cubic feet, and
the mean depth at 16 feet, or 37 per cent, of the maximum depth. The

THE FRESH- WATER LOCHS OF SCOTLAND. 101

length of the loch is 70 times the maximum depth, and 190 times the
mean depth. The Loch of Craiglush forms a simple basin, the bottom
sloping gradually down on all sides towards the deepest part without
any pronounced irregularities. The maximum depth of 44 feet was
observed in two places opposite the entrance of the Lunan burn,
approximately in the centre of the loch, but nearer the western shore
and the southern end. The area of the lake-floor covered by less than
20 feet of water is about 51 acres, or 73 per cent, of the total area of the
loch ; that covered by water between 20 and 40 feet in depth is nearly
15 acres, or 21 per cent. ; and that covered by more than 40 feet of water
is over 4 acres, or 6 per cent, of the entire area of the loch. Loch
Craiglush was surveyed on June 2, 1903, and the height of the surface
of the water above sea-level was determined by levelling from bench-
mark as being 327*6 feet, the same as Loch of Lowes, into which it
flows.

Temperature Observations. — Temperature observations taken in the
deepest part of the loch at 7.45 a.m. gave the following results: —

Surface 61°'2Fahr.

5 feet 61°'3 „

8 „ 61°'2 „

9 , 57°-4 „

10 „ 54°-5 „

20 „ 52°-0 „

30 , 50°-0 „

42 ., 49°-0 „

This series shows a rapid fall in the temperature between 8 and 10
feet, amounting to 6°-7 (a fall of 3°-8 between 8 and 9 feet, and of 2°-9
between 9 and 10 feet), the extreme range of temperature from surface
to bottom amounting to 120>2.

Loch of Lowes (see Plate XXIX.). — The Loch of Lowes, like the Loch
of Craiglush, is surrounded by trees ; its shores are mostly composed of
stony debris, and weeds are abundant off the south-western shore where
the artificial channel from the Loch of Craiglush enters. It trends in a
north-east and south-west direction, and is 1^ miles in length, with a
maximum breadth of over half a mile, the mean breadth being more
than a quarter of a mile, or 24 per cent, of the length. Its waters cover
an area of about 218 acres, or over one-third of a square mile, and it
drains directly an area of nearly 2 square miles, but since it receives
the outflow from the Loch of Craiglush its total drainage area is about
7§ square miles, an area nearly 23 times greater than the area of the
loch. Over 60 soundings were taken, the maximum depth observed
being 53 feet. The volume of water contained in the loch is estimated
at 193,973,000 cubic feet, and the mean depth at nearly 20| feet, or
39 per cent, of the maximum depth. The length of the loch is 138 times

102 BATHYMETR1CAL SURVEY OF

the maximum depth, and 360 times the mean depth. The Loch of
Lowes forms on the whole a simple basin, but with here and there
minor undulations of the bottom. The maximum depth of 53 feet was
observed approximately in the centre of the loch, but a short distance
to the north of it a sounding of 42 feet was taken apparently surrounded
on all sides by shallower water, and to the west a depth of 7 feet was
observed with deeper water all round. Generally speaking, the slope
of the bottom is gentle, there being no evidence of any steep gradients.
The area of the lake-floor covered by less than 20 feet of water is about
120 acres, or 55 per cent, of the total area of the loch ; that covered by
water between ^0 and 40 feet in depth is about 79 acres, or 26 per cent. ;
and that covered by more than 40 feet of water is about 19 acres, or
9 per cent, of the entire area of the loch. The Loch of Lowes was
surveyed on June 2, 1903, the same day as the Loch of Craiglush, and
the elevation of the two lochs above the sea was found by levelling to be
identical, viz., 327-6 feet. When levelled by the Ordnance Survey
officers on July 13, 1899, the elevation was found to be 327-9 feet above
the sea.

Temperature Observations. — Temperature observations taken in the
deepest part of the loch at 1.15 p.m. gave the following results : —

Surface 60°'OFahr.

10 feet 59°-5 ,,

13 „ 57°'0 „

15 „ 52°-2 „

20 „ 51°-0 „

30 „ 50°-2 ,,

40 „ 50°-0 „

50 ,, 50°'0 ,,

This series shows a range of 10° in the temperature throughout the
50 feet of water, the greatest fall being one of 40>8 between 13 and 15
feet. Compared with the temperatures taken in the Loch of Craiglush
earlier in the day, this series shows a smaller range (the temperature at
the surface being lower and at the bottom higher, notwithstanding the
greater depth), and the position of the greatest fall in the temperature
was observed at a greater depth, viz., between 10 and 15 feet, as
compared with between 8 and 10 feet in the Loch of Craiglush.

Loch of Butter stone (see Plate XXIX.).— The Loch of Butterstone
(or Butterston) is, like the two neighbouring lochs, to a large extent
surrounded by trees; its shores are sandy or weedy, and many coots
nest among the weeds. It is almost circular in outline, the greatest
diameter (or length) from north-east to south-west being about three-
fifths of a mile, while the maximum breadth from north-west to south-
east is about half a mile, the mean breadth being over a quarter of a mile,
or 50 per cent, of the length. Its waters cover an area of about 108 acres,

THE FRESH- WATER LOCHS OF SCOTLAND. 103

or one-sixth of a square mile, and it drains directly an area of over two-
thirds of a square mile, but since it receives the outflow from Lochs
Craiglush and Lowes, its total drainage area is about 8J square miles —
an area 49 times greater than the area of the loch. Over 50 soundings
were taken, the maximum depth observed being 25 feet. The volume
of water contained in the loch is estimated at 53,238,000 cubic feet,
and the mean depth at 11| feet, or 45 per cent, of the maximum depth.
The length of the loch is 122 times the maximum depth and 271 times
the mean depth. The Loch of Butterstone forms a simple basin, the
maximum depth of 25 feet being observed approximately in the centre
of the loch, but nearer the western and southern shores. The deeper
water approaches much closer to the western than to the eastern shore,
off which the shallow water extends some distance into the loch,
especially opposite the point at the outflow, where the 10-feet contour-
line makes a great bend inward; this bend affects also the 20 -feet
contour-line, so that the 20-feet basin becomes somewhat crescent-
shaped. The area of the lake-floor covered by less than 10 feet of water
is about 52 J acres, or 48J per cent, of the entire area of the loch ; that
covered by water between 10 and 20 feet in depth is about 39J acres, or
36 \ per cent. ; and that covered by more than 20 feet of water is about
16 acres, or 15 per cent, of the total area of the loch. The Loch of
Butterstone was surveyed on June 1, 1903, and the surface of the water
was found by levelling from bench-mark to be 314'4 feet above sea-level.
The Ordnance Survey officers determined the level on July 31, 1899, as
being 314*8 feet above the sea.

Temperature Observations. — Temperature observations were taken
in the deepest part of the loch in the afternoon of June 1, 1903, with
the following results : —

Surface 63°-0 Fahr.

5 feet ... 62°-8 „

8 , 62°-5 „

10 , 57°'0 „

25 „ 53° 0 „

This series shows a range from surface to bottom of 10°, the greatest
fall being one of 5°-5 between 8 and 10 feet. The water was warmer at
all depths than in Lochs Craiglush and Lowes at corresponding depths ;
the greatest decrease of temperature was observed at the same depth as
in Loch Craiglush ; the range of temperature was the same as that in
Loch Lowes, although there is only half the depth of water.

Loch of Clunie (see Plate XXX.). — The Loch of Cluuie lies in a well-
wooded valley, and is surrounded by cultivated ground, except at
Forneth woods. The castle on the island in the loch, which seems to be
artificial, is said to have been the birthplace of the Admirable Crichton.
On this island a pair of herons built their nest in 1903, but nest and

104 BATHYMETRICAL SURVEY OF

young were destroyed by excursionists. Near the middle of the north
side of the loch, and about 100 yards from the shore, is a mound of
stones (two of which were above the water on the date of the survey),
said to have been put down to indicate a sandbank. The Lunan burn
at the exit of the loch is a long weedy stretch with no perceptible
current, the fall to the Loch of Drumellie being only 10 feet in a mile.
The Loch of Clunie is triangular in outline, with the apex pointing
south. The diameter from east to west and from north to south is
nearly equal, the length from east to west being rather less than two-
thirds of a mile, while the maximum breadth is slightly less, the mean
breadth being one-third of a mile, or 55 per cent, of the length. Its
waters cover an area of 134 acres, or over one-fifth of a square mile,
and it drains directly an area of nearly 8 square miles, but since
it receives the outflow from the Lochs of Butterstone, Lowes, and
Craiglush, its total drainage area is over 16^ square miles — an area
nearly 78 times greater than the area of the loch. Over 80 soundings
were taken, the maximum depth observed being 69 feet. The volume
of water contained in the loch is estimated at 170,265,000 cubic feet,
and the mean depth at 29 feet, or 42 per cent, of the maximum depth.
The length of the loch is 47 times the maximum depth, and 112 times
the mean depth. The Loch of Clunie forms, generally speaking, a
simple basin, but with a few minor undulations of the bottom. The
25-feet basin corresponds approximately with the outline of the loch,
but the 50-feet basin is somewhat irregular in outline, owing to two
elevations of the lake-floor : (1) Near the north-east angle of the loch,
where a sounding of 24 feet was taken, with depths of 33 and 35 feet
on one side and depths of 52 and 69 feet on the other ; and (2) a short
distance to the west, where a depth of 45 feet was observed, with 52
feet on one side and 60 feet on the other. These two elevations give
rise to a peculiar constriction in the outline of the 50-feet basin,
and the shallower elevation is the more striking because of its close
proximity to the deepest part of the loch, the maximum depth of 69
feet having been found comparatively close to the eastern shore. A
moderately steep slope was observed off the northern shore, opposite
the east lodge of Forneth House, where a depth of 14 feet was found
about 60 feet from the shore, equal to a gradient of 1 in 4'3. The area
of the lake-floor covered by less than 25 feet of water is about 68 acres,
or 51 per cent, of the total area of the loch; that covered by water
between 25 and 50 feet in depth is about 39 acres, or 29 per cent. ; and
that covered by more than 50 feet of water is about 27 acres, or 20 per
cent, of the entire area of the loch. The Loch of Clunie was surveyed
on June 4, 1903, and the elevation of the lake-surface above the sea
was determined, by levelling from bench-mark, as being 156*55 feet;
when levelled by the Ordnance Survey officers on September 12, 1899,
the elevation was found to be 156-3 feet.

THE FRESH- WATER LOCHS OF SCOTLAND. 105

Temperature Observations. — Temperature observations taken at
6.30 p.m. in the deepest part of the loch gave the following results : —

Surface ...

62°, 3 Fa

IT.

5 feet
K)

62°-0 ,
54° -2 ,

Ifl

52°-4 ,

25

49°-0 ,

50 .

47° -4 ,

65 .

47° '2

This series shows a range of temperature from surface to bottom
amounting to 15°'l, the greatest fall being one of 70-8 between 5 and 10
feet, there being a further fall of 3°-4 between 15 and 25 feet.

Loch of Drumellie (see Plate XXX.). — The Loch of Drumellie (or
Marlee Loch) lies about a mile to the east of the Loch of Clunie, and is
surrounded by cultivated ground, the fields sloping gently up on all
sides. Its shores are stony or weedy, and the narrow portion leading
to the outflow is quite choked up with weeds, except for an artificial
channel about 4 feet deep leading to the landing-stage, where the burn
flows out over a weir. Large yellow masses of decaying vegetable matter
were floating everywhere. The loch is about seven-eighths of a mile in
length, with a maximum breadth of nearly half a mile, the mean breadth
being nearly one-third of a mile, or 37 per cent, of the length. Its waters
cover an area of about 175 acres, or over a quarter of a square mile, and
it drains directly an area of over 6^ square miles, but since it receives
the outflow from the Loch of Clunie and from Rae Loch, its total
drainage area is about 23 J square miles — an area 86 times greater than
the area of the loch. Over 70 soundings were taken, the maximum depth
observed being 58 feet. The volume of water contained in the loch is
estimated at 221,902,000 cubic feet, and the mean depth at 29 feet, or
50 per cent, of the maximum depth. The length of the loch is 78 times
the maximum depth and 156 times the mean depth. The Loch of
Drumellie forms a flat-bottomed basin, the bottom sinking in two
places below the 50-feet line, with shallower water between. The
south-eastern 50-feet basin is based upon two soundings of 51 feet,
while in the north-western one the maximum depth of 58 feet was
observed, situated less than a quarter of a mile from the west end
of the loch. The average slope of the bottom is gentle, the steepest
slope observed being about midway along the southern shore, where
a sounding of 20 feet was taken about 100 feet from the shore, giving
a slope of 1 in 5. The area of the lake-floor covered by less than
25 feet of water is about 72 acres, or 41 per cent, of the total area of
the loch; that covered by water between 25 and 50 feet in depth is
about 83 acres, or 47 per cent. ; and that covered by more than 50 feet
of water is about 20 acres, or 12 per cent, of the entire area of the loch.

106 BATHYMETRICAL SURVEY OF

The fact that the area between the 25- and 50-feet contour-lines is
greater than the area between the shore and the 25 -feet line proves the
flat-bottomed nature of the basin, as well as the fact that the mean
depth is fully half the maximum depth. The Loch of Drumellie was
surveyed on the same day as the Loch of Clunie, June 4, 1903 ; the
elevation above the sea was determined by levelling from bench-mark as
being 146*7 feet. The Ordnance Survey officers found the level of the
lake-surface to be 147 feet above the sea on September 19, 1899.

Temperature Observations. — Temperature observations taken in the
deepest part of the loch at 11.30 a.m. gave the following results: —

Surface «0°'2 Fahr.

10 feet 59° 0 „

15 „ 53°-7 „

20 „ 50°-7 „

30 „ 49° 5 „

40 „ 49°-2 „

58 ,, 48°7 ,,

This series shows a range of temperature from surface to bottom of
11°'5, the greatest fall being one of 50<3 between 10 and 15 feet, with
a further fall of 3° between 15 and 20 feet. Compared with the
temperatures taken in the Loch of Clunie in the evening of the same
day, this series shows a much smaller range of temperature, the surface
temperature being 2° lower and the bottom temperature 10<5 higher,
although the difference in depth is only 7 feet ; the position of greatest
fall in the temperature is nearer the surface in the Loch of Clunie,
and the amount of fall is greater.

Rae Loch (see Plate XXX.). — Rae Loch (or Ardblair Loch) lies a
quarter of a mile to the east of the Loch of Drumellie, into which it
flows, and about a mile to the west of Blairgowrie. It is surrounded
by low fields and wooded country, and its shores are all weedy, while the
western portion of the loch is quite filled with weeds. The water
formerly stood at a higher level, and frequently flooded the road on the
north side ; it was consequently lowered about 10 feet by a cutting,
which has since, however, become choked up. It is under half a mile
in length, less than one-fifth of a mile in maximum breadth, the mean
breadth being about one-ninth of a mile, or 25 per cent, of the length.
Its waters cover an area of about 30 acres, and it drains an area seven
times greater — an area of over one-third of a square mile. Over 30
soundings were taken, the maximum depth observed being 16 feet.
The volume of water is estimated at 8,727,000 cubic feet, and the mean
depth at 6J feet, or 31 per cent, of the maximum depth. The deeper
water occurs near the eastern end, off which the slope is steep ; at one
point a sounding of 10 feet was taken only 20 feet from the shore, giving
a gradient of 1 in 2. The area of the lake-floor covered by less than

THE FRESH-WATER LOCHS OF SCOTLAND. 107

10 feet of water is about 24 acres, or 80 per cent, of the total area of the
loch. Rae Loch was surveyed on June 23, 1903, and the level of the
lake-surface above the sea was determined, by levelling from bench-
mark, as 195'2 feet.

Temperature Observations. — Temperatures taken in the deepest part
gave the following results : —

Surface 60°'8 Fahr.

5 feet 60°'5 „

10 „ 57°'9 „

15 „ 57°'l „

The range of temperature throughout the 15 feet of water was 3°'7,
there being a fall of 2°'6 between 5 and 10 feet.

Fingask Loch (see Plate XXX.). — Fingask Loch lies about three-
quarters of a mile to the south-east of Rae Loch, and 1J miles to the
south-west of Blairgowrie. It is surrounded by low cultivated ground,
and weeds occur in the north-western angle of the loch and near the
shore in other places, but not in any great abundance. It receives the
outflow from White Loch by a mill lade, and it flows into the Lunan
burn by a short sluggish stream. It is over one-third of a mile in
length from north-west to south-east, with a maximum breadth of a
quarter of a mile, the mean breadth being about one-seventh of a mile,
or 41 per cent, of the length. Its waters cover an area of over 32 acres,
and it drains directly an area of about one-sixth of a square mile, but,
since it receives the outflow from the White Loch, its total drainage area
is over a quarter of a square mile — an area 4J times greater than the
area of the loch. Nearly 40 soundings were taken, the maximum depth
observed being 48 feet. The volume of water is estimated at 32,182,000
cubic feet, and the mean depth at nearly 23 feet, or 48 per cent, of the
maximum depth. Fingask Loch forms a simple basin, the bottom
sloping down gradually on all sides to the deepest part, which is,
approximately, centrally placed. The north-western angle is shallow
and obstructed by weeds, but the remainder of the loch is comparatively
deep, and forms a sub-circular basin. The slope of the bottom is in
places moderately steep, as, for instance, off the northern shore, where
a sounding of 20 feet was taken about 80 feet from the shore, giving a
gradient of 1 in 4. The area of the lake-floor covered by less than
10 feet of water is about 9 acres, or 27 \ per cent, of the total area of the
loch ; that covered by water between 10 and 25 feet in depth is about
8J acres, or 26 J per cent. ; that covered by more than 25 feet of water is
about 15 acres, or 46 per cent, of the entire area of the loch. This last
percentage indicates the flat-bottomed character of the basin. Fingask
Loch was surveyed on June 19, 1903, and its elevation above the sea
was determined by levelling from the White Loch (which was surveyed
on the same day) as being 140*6 feet.

108 BATHYMETRICAL SURVEY OF

Temperature Observations. — Temperature observations taken in the
deepest part of the loch in the afternoon of June 19, 1903, gave the
following results : —

Surface 58°'8 Fahr.

10 feet 57°'6 „

20 „ 55°-3 „

30 „ 49°-4 „

45 „ 48°-7 „

This series shows a range of temperature from surface to bottom of
about 10°, there being a fall of about 6° between 20 and 30 feet.

White Loch (see Plate XXX.).— The White Loch lies immediately
to the east of Fingask Loch, into which it flows by an artificial mill-lade,
and the water has apparently been raised several feet by damming, in
order to supply the mill. At the east end of the loch, in the direction of
the Black Loch, a copious burn flows out of the bank into the White
Loch, but there is no evidence that it comes from the Black Loch, and
the local people think the burn has its source in a spring. The eastern
portion of the loch, called the Eie Loch, is separated from the larger
and deeper portion by a narrow constriction ; it is shallow, and almost
filled with weeds, with a central depression 15 feet in depth. Tradition
says this was once a separate loch, and that the connection was cut, the
depth in the constriction being 2 feet. The loch is surrounded by
gently sloping fields and wooded ground. It is about one-third of a
mile in length, with a maximum breadth of one-seventh of a mile, the
mean breadth being one-fourteenth of a mile, or 20 per cent, of the
length, and its waters cover an area of about 15 acres. Over 40
soundings were taken, the maximum depth observed being 32 feet.
The volume of water is estimated at 8,425,000 cubic feet, and the mean
depth at 13 feet, or 41 per cent, of the maximum depth. The length of
the loch is 56 times the maximum depth and 138 times the mean depth.
The western portion of the White Loch forms a simple basin, the
bottom sloping gently down on all sides to the deepest part, which is
approximately centrally placed. There is no evidence of any pronounced
irregularity of the lake-floor, nor of any steep slope. The area of the
lake-floor covered by less than 10 feet of water is about 8 acres, or 52
per cent, of the total area of the loch ; that covered by water between
10 and 25 feet in depth is over 4 acres, or 29 per cent. ; and that
covered by more than 25 feet of water is about 3 acres, or 19 per cent.
White Loch was surveyed on the same day as Fingask Loch (June 19,
1903), and its elevation above the sea was determined, by levelling from
bench-mark, as being 153 '7 feet.

Temperature Observations. — Temperatures taken in the deepest part
of the loch gave the following results : —

THE FRESH- WATER LOCHS OF SCOTLAND. 109

Surface 59°OFahr.

10 feet 58°-0 „

•2<) ,, 52°-5 „

30 „ 50°-2 „

This series shows a range of 8°'8 in the temperature of the water from
surface to bottom, there being a fall of 5°*5 between 10 and 20 feet.
Compared with the temperatures taken in Fingask Loch on the same
day, this series indicates that the temperature of the upper layers of
water was comparable in both lochs, but at 20 feet the temperature was
nearly 3° lower than at that depth in the larger loch, the position of
the great fall in the temperature being nearer the surface in the smaller
loch.

Black Loch (see Plate XXX.).— The Black Loch lies immediately
to the east of the White Loch, the main road from Perth to Blairgowrie
passing between them. Neither inflow nor outflow was observed, but
if the water were to rise 6 or 8 feet it might overflow by the channel
under the road into the White Loch. It is almost surrounded by woods,
and the shores are weedy. It is over a quarter of a mile in length,
nearly one-tenth of a mile in maximum breadth, and its waters cover
an area of about 8 acres. Nearly 30 soundings were taken, and the
maximum depth observed was 7 feet. The voluma of water is estimated
at 1,611,000 cubic feet, and the mean depth at 4| feet, or 68 per cent,
of the maximum depth. The loch is almost of uniform depth, only
three of the soundings being under 5 feet, and these were near the east
end, so that the great body of water is from 5 to 6 feet in depth, the
area of the lake-floor covered by more than 5 feet of water being about
5 acres, or 64 per cent, of the total area of the loch. It was surveyed
on June 23, 1903, by means of a portable boat lent by Mr. Anderson,
carried over from Druidsmere, and the elevation above the sea was
determined, by levelling from bench-mark, as being 162-8 feet.

Temperature Observations. — The temperature of the surface water
in the main body of the loch was 60°'l, while in the eastern portion it
was 59°'0. The water in the eastern basin was clearer as well as colder,
as though there might be a spring there. Temperatures taken in the
deepest part of the loch gave the following results : —

Surface 60°'l Fahr.

3 feet ... 60°-0 ,,

4 „ 59°-8 „

5 „ , 58°'5 „

6 „ 57c'l „

showing a range of 3°*0 throughout the 6 feet of water.

To the south-west of the Black Loch lies Hare Myre, which was
visited on June 22, 1903, but could not be sounded because no boat was
available. The keeper said it was all shallow, and that the oars when

110 BATHYMETRICAL SURVFA7 OF

rowing stirred up the mud everywhere, the depth probably not exceeding
2 feet. More than two-thirds of the superficial area is overgrown with
weeds, there being a very little open water of a black colour. Neither
inflow nor outflow was seen, but a drain was cut at some remote time to
conduct the water to the south-west, where it joined the burn flowing
from Stormont Loch to the Lunan burn. The loch does not now rise to
overflow, and the water is stagnant, but looks clearer than that in the
Stormont Loch.

The term Stormont Lochs is ^sometimes applied to the group of small
lochs in this neighbourhood, including Loch Bog (or Stormont Loch),
Monk Myre, Hare Myre, Black, White, Fingask, and Rae. Myriads
of water-fowl breed on these lochs, and ducks of several species were
nesting on the artificial island in Stormont Loch at the time of the
survey.

Stormont Loch (see Plate XXX.). — Stormont Loch (or Loch Bog) lies
immediately to the east of Hare Myre. It is a stagnant bog in a flat
country, surrounded by woods and fields, and it receives no water
except rains. It rarely rises high enough to overflow, but in February,
1903, it did so, the outflow being artificial and leading to the Lunan
burn. The water is turbid, light brown in colour, and dense with
animals — so much so that the tow-nets could only be used for a very
short time. About half the area of the loch is unapproachable on
account of weeds, and the other half is very uniform in depth (2 to 3
feet), and free from weeds. The keepers say that the mud on the bottom
is of great depth, 18-feet poles having been sunk in it, and that it has
accumulated greatly of late years. It is said that within the memory
of old men now living there was a depth of 17 feet near where the boat-
house was built (of which the remains are still visible). Stormont Loch
is about two-thirds of a mile in length, and one-third of a mile in
maximum breadth, the mean breadth being over one-sixth of a mile,
or 27 per cent, of the length. Its waters cover an area of about 74 J
acres, and the maximum depth of 3 feet was observed in several places
near the eastern shore. The volume of water is estimated at 4,867,000
cubic feet. It was surveyed on June 22, 1903, and its elevation above
the sea was determined by levelling from bench-mark as 168-1 feet,
which is identical with the level when visited by the Ordnance Survey
officers on June 26, 1900. The temperature of the surface water at
1 p.m. on June 22, 1903, was 64°-0.

Monk Myre (see Plate XXX.). — Monk Myre lies about half a mile
to the east of the Stormont Loch, but it flows in the opposite direction
by the Monkmyre burn into the river Ericht; there are no inflowing
burns. It is surrounded by flat grassy country, and is divided into two
portions by a narrow constriction, through which it is now impossible to

THE FRESH- WATER LOCHS OF SCOTLAND. Ill

take a boat. The smaller western portion is mostly overgrown by weeds,
with a very little open water, and never entirely freezes over, owing
probably to the existence of numerous springs. Monk My re is over
half a mile in length, with a maximum breadth of over one-seventh of a
mile, the mean breadth being about one-thirteenth of a mile, or 14 per
cent, of the length, and its waters cover an area of about 25 acres. Over
30 soundings were taken, and the maximum depth observed was 12 feet.
The volume of water is estimated at 5,552,000 cubic feet, and the mean
depth at 5 feet, or 42 per cent, of the maximum depth. The loch is
a shallow basin with rather uneven floor ; the deepest part is towards
the northern shore, where neighbouring soundings of 10 and 12 feet
were taken, the remaining soundings being under 10 feet. The area
of the lake-floor covered by less than 10 feet of water is equal to 98 \
per cent, of the total area. Monk Myre was surveyed on June 20, 1903,
but its elevation above the sea could not be ascertained. Temperatures
taken at 7 a.m. gave 55°-8 at the surface and at a depth of 10 feet.

Long Loch and Pitlyal Loch form the headwaters of the Dighty
burn, which flows eastward and enters the estuary of the Tay at
Monifieth; a burn flows from Long Loch to Pitlyal Loch.

Long Loch (see Plate XXX.). — The Long Loch is bordered on the
west by steep, grassy hills, while the eastern shore is low and wooded.
No burns of any size enter the loch, but there are many springs on
the hillside to the west. It contains pike and perch. The outflow is
artificial, by dam and sluice ; but at the time of the survey the water
was very low, and very little water was flowing out at the sluice. The
dotted line on the map shows approximately the shore-line on the date
of the survey, and the water would have to rise 4J feet to reach the
overflow. Long Loch trends in a north-east and south-west direction,
and is very peculiar in outline, presenting a close resemblance to a dog's
body and head without legs, the portion represented by the dog's nose
being filled with weeds. It is nearly three-quarters of a mile in length,
with a maximum breadth of over a quarter of a mile, the mean breadth
being one-sixth of a mile, or 24 per cent, of the length. Its waters
cover an area of about 74 acres. Over 50 soundings were taken, the
maximum depth observed being 42 feet. The volume of water contained
in the loch is estimated at 31,893,000 cubic feet, and the mean depth
at 10 feet, or 24 per cent, of the maximum depth. The length of the
loch is 88 times the maximum depth, and 373 times the mean depth.
Generally speaking, the loch forms a simple basin, with a few minor
undulations of the bottom, and the slope is steeper off the western
than off the eastern shore. The maximum depth of 42 feet was observed
near the centre of the loch, but considerably nearer the western than
the eastern shore. In this locality the slope is moderately steep, a
sounding of 12 feet being recorded about 50 feet from the shore, giving

112 BATHYMETRICAL SURVEY OF

a gradient of 1 in 4-2. The area of the lake-floor covered by less than
10 feet of water is about 52 acres, or 70 per cent, of the total area of
the loch; that covered by water between 10 and 25 feet in depth is
about 18 acres, or 25 per cent. ; and that covered by more than 25 feet
of water is about 4 acres, or 5 per cent, of the entire area of the
loch. Loch Long was surveyed on June 24, l£)03, and its elevation
above the sea was determined, by levelling from bench-mark, as 724-0
feet.

Temperature Observations. — Temperatures taken in the deepest part
of the loch gave the following results : —

Surface 58°'4Fahr.

10 feet 57°'0 „

15 „ -.. ... 55°-4 ,,

20 „ 54°-0 ,,

40 „ 53°-2 ,,

This series shows a range of temperature throughout the 40 feet of
water of 5°-2, there being a fall of 3° between 10 and 20 feet.

Pitlyal Loch (see Plate XXX.). — Pitlyal Loch (or Round Loch, or
Thriepley Loch) lies about a quarter of a mile to the south-east of Long
Loch, and is surrounded by gently sloping cultivated fields. There is
a fringe of weeds all round the shore. Grebe and coots were seen, and
there were swans on the small islet with bushes about 100 feet north-
west of the boathouse. The outflow to the Dighty burn is by artificial
dam and sluice; the water may rise 2 to 3 feet above its level on the
date of the survey. The loch is well described by its name " Round
Loch," for it is subcircular in outline, though rather longer from north
to south than from east to west. It is over one-fifth of a mile in length,
with a maximum breadth of about one-seventh of a mile, the mean
breadth being about one-ninth of a mile, or 52 per cent, of the length,
and its waters cover an area of about 15 acres. Thirty soundings were
taken, the maximum depth observed being 19 feet. The volume of
water is estimated at 5,347,000 cubic feet, and the mean depth at
8J feet, or 44 per cent, of the maximum depth. Pitlyal Loch forms a
simple basin, but the deeper water is found towards the western shore,
so that the slope of the bottom is steeper off that shore than off the
eastern shore; a sounding of 11 feet was taken about 100 feet from the
western shore, and the maximum depth of 19 feet was recorded about
150 feet from that shore. The area of the lake-floor covered by less
than 10 feet of water is nearly 10 acres, or 65 per cent, of the total
area of the loch. Pitlyal Loch was surveyed on the same day as Long
Loch (June 24, 1903), and its elevation above the sea was determined
by levelling from bench-mark as being 606-5 feet.

THE FRESH-WATER LOCHS OF SCOTLAND.

113

Temperature Observations. ^Temperature observations gave the
following results : —

Surface

10 feet

11 „

12 „

13 ,

59°OFahr.
590O „
58° -8 „
55° "8 „
55°-0

This series shows that the upper 10 feet of water had a uniform
temperature, but between 11 and 12 feet there was a fall of 3°, the
extreme range from surface to bottom being 4°.

Loch Freuchie (see Plate XXXI.). — Loch Freuchie (or Fraochie),
near Amulree, is a very pretty loch amid pastoral scenery, the grassy

FIG. 25. LOCH FBEUCHIE, LOOKING S.E. FBOM BBIDGE OVER INLET.

(Photograph by R. Dykes.)

shores sloping gently up on both sides, with here and there patches of
wood. It was formerly a good trout loch, but in recent years it has
been overrun by pike ; steps have been taken, however, to keep down
the pike, and the fishing is now improving. It flows by the river Bran
into the river Tay at Dunkeld. Loch Freuchie trends in a north-
west and south-east direction, widest in the north-western half and
narrowing towards the south-east end. It is If miles in length, with a
maximum breadth of nearly half a mile, the mean breadth being about
one-third of a mile, or 18 per cent, of the length. Its waters cover an
area of about 348 acres, or over half a square mile, and it drains an
area 55 times greater — an area of over 23 square miles. Nearly 90
soundings were taken, the maximum depth observed being 62 feet. The
volume of water contained in the loch is estimated at 346,564,000 cubic
feet, and the mean depth at 23 feet, or 37 per cent, of the maximum

i

114 BATHYMETRICAL SURVEY OF

depth. The length of the loch is 148 times the maximum depth and 402
times the mean depth. Loch Freuchie forms on the whole a simple
basin, but with a few minor undulations of the bottom. The 25-feet
basin is sinuous in outline, especially towards the south-east end, and is
over 1J miles in length, approaching close to the north-west end, but
distant less than a quarter of a mile from the south-east end. The
50-feet basin, half a mile in length, is contained in the northern half of
the loch, and nearer the eastern than the western shore, the maximum
depth of 62 feet having been observed in two places, with soundings of
60 feet between them. Cones of alluvium have been formed at the
mouths of the Turrerich burns at the northern angle of the loch, and at
the entrance of the Allt a' Mhuilimi about midway along the western
shore. The area of the lake-floor covered by less than 25 feet of water
is about 225 acres, or 65 per cent, of the total area of the loch ; that
covered by water between 25 and 50 feet in depth is about 95 acres, or

27 per cent. ; and that covered by more than 50 feet of water is about

28 acres, or 8 per cent, of the entire area of the loch. Loch Freuchie
was surveyed on June 5, 1903, and the height of the surface of the
water above the sea was determined, by levelling from bench-mark, as
being 867-45 feet ; when levelled by the officers of the Ordnance Survey
on August 17, 1899, the elevation was found to be 870-8 feet above
sea-level.

Temperature Observations, — Temperature observations taken in the
deepest part of the loch at 7 p.m. gave the following results : —

Surface 58°'6 Fahr.

10 feet 58°-3 „

15 „ 57°'6 ,,

25 , 53°'0 „

40 „ 50°'0 ,,

60 „ 49°-4 „

This series shows a range of temperature from surface to bottom of
9°-2, there being a fall of 4°-6 between 15 and 25 feet, and a further
fall of 3°-0 between 25 and 40 feet.

Loch Hoil (see Plate XXXI.).— Loch Hoil (or Oyl, or Thuill) lies to
the south of Aberfeldy, and flows by the Cochill burn into the river
Bran. It contains trout, perch, grayling, and gudgeon. It is sur-
rounded by low, rounded, hummocky, heather-clad hills. Its shores are
stony ; the bay leading to the outflow is very shallow and full of weeds.
It is very irregular in outline, and over one-third of a mile in length
from north-west to south-east, under one-third of a mile in maximum
breadth from north-east to south-west, the mean breadth being one-
seventh of a mile, or 43 per cent, of the length. Its waters cover an
area of about 35 acres, and it drains an area six times greater — an area

THE FRESH- WATER LOCHS OF SCOTLAND. 115

of over one-third of a square mile. Nearly 40 soundings were taken,
the maximum depth observed being 46 feet. The volume of water is
estimated at 29,271,000 cubic feet, and the mean depth at 19 feet, or
42 per cent, of the maximum depth. The length of the loch is 40 times
the maximum depth and 100 times the mean depth. Loch Hoil
consists of a main body, which trends almost north and south, sending
out an arm in an easterly direction leading to the outflow. This arm
is shallow, while the body of the loch is comparatively deep; at the
junction of the arm and body is a heap of stones about 200 feet from
the eastern shore. The body of the loch forms a simple basin, the
bottom sloping down on all sides towards the deepest part, which is
approximately centrally placed, but rather nearer the northern than
the southern end. The average slope of the bottom is gentle, the
steepest gradient observed being one of 1 in 4-6 off the southern shore,
where a sounding of 13 feet was taken 60 feet from the shore. The area
of the lake-floor covered by less than 20 feet of water is about 24 acres,
or 68 per cent, of the total area of the loch; that covered by water
between 20 and 40 feet in depth is about 9 acres, or 26 per cent. ; and
that covered by more than 40 feet of water is about 2 acres, or 6 per
cent. The loch was surveyed on May 28, 1903, and, from spot-levels
near the loch, it was calculated that the surface of the water was about
1600 feet above the sea.

Temperature Observations. — Temperatures taken in the deepest part
of the loch gave the following results : —

Surface 57°'0 Fahr.

10 feet ... 52°-0 „

20 „ 48°-0 „

40 „ 47°'0 „

This series shows a range of 10° from surface to bottom, there being
a fall of 5° between the surface and 10 feet, and a further fall of 4°
between 10 and 20 feet.

Loch Fender (see Plate XXXI.). — Loch Fender lies to the north of
Loch Freuchie, and flows by the Glenfender burn into the river Bran.
It contains large trout, but the fishing, which is preserved, is uncertain,
sometimes yielding splendid sport, at other times none at all. It was
surveyed on the same day as Loch Freuchie by means of a boat kindly
supplied by Mr. Bulloch of Kinloch. The Marquis of Breadalbane
sounded Loch Fender about 40 years ago from a portable boat, and
found a maximum depth of about 30 yards ( = 90 feet) ; the maximum
depth recorded by the Lake Survey was 78 feet. Loch Fender is thus
extremely interesting on account of its great depth, considering its
small dimensions. The shores are rocky all round, and the southern
shore is a steep slope of bare rock, rising gradually to Creag an Loch ;

116 BATHYMETRICAL SURVEY OF

at other places the shores are less steep, and surrounded by smooth,
rounded, heather-covered hills. The water was very dark in colour,
and, though there was apparently no great amount of inflow, there was
a considerable outflow. Loch Fender is one-third of a mile in length
from north-east to south-west, and one-fifth of a mile in maximum
breadth, the mean breadth being over one-tenth of a mile, or 32 per
cent, of the length. Its waters cover an area of over 22 acres, and it
drains an area nine times greater — an area of over one-third of a square
mile. Nearly 60 soundings were taken, the maximum depth observed
being 78 feet. The volume of water contained in the loch is estimated
at 30,998,000 cubic feet, and the mean depth at 31| feet, or 41 per
cent, of the maximum depth. The length of the loch is 22 times the
maximum depth and 55 times the mean depth. Loch Fender forms a
simple basin, the bottom sloping down on all sides to the deepest part,
which is approximately centrally placed, but nearer the north-east than
the south-west end, the maximum depth of 78 feet having been observed
about 300 feet from the north-eastern shore. The average slope of the
bottom is very steep, especially off the south-eastern shore, where were
recorded soundings of 29 feet 20 feet from shore, 26 feet 30 feet from
shore, and 17 feet 20 feet from shore, giving gradients of 1 in 0*7 and
1 in 1-2. Off the north-western shore the gradient is gentler, and the
north-west angle, where the burn flows into the loch, is comparatively
shallow and obstructed by weeds. The area of the lake-floor covered
by less than 25 feet of water is about 11 acres, or 51 per cent, of the
total area of the loch ; that covered by water between 25 and 50 feet in
depth is about 5 acres, or 21 per cent. ; and that covered by more than
50 feet of water is about 6 acres, or 28 per cent, of the entire area of
the loch. Loch Fender was surveyed on June 5, 1903, and, from spot-
levels near the loch, it was estimated that the elevation of its surface
was approximately 1888 feet above sea-level.

Temperature Observations. — Temperatures taken in the deepest part
of the loch at 1 p.m. gave the following results: —

Surface 58°-OFahr.

5 feet 57°-8 ,,

10 „ 52° -0 „

15 ,, ... ... 4o°-0 ,,

25 ,, 44°-0 f>

50 „ 43°'0 „

75 „ ... 42°-4 „

This series shows a range of temperature from surface to bottom
amounting to 15°-6, there being a fall of 12°-8 between 5 and 15 feet
(i.e. 5°-8 between 5 and 10 feet, and 7°-0 between 10 and 15 feet). The
decrease of temperature in the layer of water between 10 and 15 feet is
thus equal to l°-4 per foot, whereas the fall is only 1° in the underlying
layer between 15 and 25 feet.

THE FRESH- WATER LOCHS OF SCOTLAND.

117

Loch Turret (see Plate XXXII.).— Loch Turret, in Glen Turret,
near Crieff, is used as the source of the water supply to the town of
Crieff. It is a good trout loch, but strictly preserved, and is situated
amid wild and beautiful scenery, the hills being steep and high on both
sides, especially to the west, where crags border the loch. It flows by
the Turret burn into the river Earn, and it receives the waters from
the little Lochan Uaine, lying at the head of the glen, which was
surveyed on the same day by request of the proprietor. Loch Turret
trends in a north-west and south-east direction, and is widest towards
the southern end, narrowing somewhat towards the northern end. It
is over a mile in length, and over one-third of a mile in maximum
breadth, the mean breadth being a quarter of a mile, or 24 per cent, of

FIG. 26. — LOCH TURRET., LOOKING N.W.
(Photograph by R. Dykes.)

the length. Its waters cover an area of about 164 acres, or a quarter
of a square mile, and it drains an area 23 times greater — an area of
nearly 6 square miles. Seventy soundings were taken, the maximum
depth observed being 79 feet. The volume of water contained in the
loch is estimated at 227,718,000 cubic feet, and the mean depth at
32 feet, or 40 per cent, of the maximum depth. The length of the
loch is 70 times the maximum depth and 173 times the mean depth.
Loch Turret forms on the whole a simple basin, the deeper water
approaching nearer to the northern end and the western shore. The
wide southern portion is comparatively shallow (under 20 feet), with
one or two slight irregularities of the bottom, as, for instance, near the
south-western angle of the loch, where soundings of 8 feet and 9 feet

118 BATHYMETRICAL SURVEY OF

were recorded, surrounded in each case by deeper water. These shallow
soundings mark the position of a rocky ridge, said to cross the loch, and
to be a continuation of the rocky ridge on the east shore, now used as a
quarry. About midway along the eastern shore there is a slight con-
striction in the outline of the loch at the entrance of the Allt Bhaltair,
apparently due to the material brought down by that stream, and in
this position a slight shoaling of the bottom in the centre of the loch is
observable, the depth being 73 feet, with two soundings of 77 feet to the
north, and soundings of 77 and 79 feet to the south. The 2 5 -feet basin
is about three-quarters of a mile in length, approaching to within 100
feet from the northern end, and a quarter of a mile from the southern
end. The slope of the bottom is steeper off the western than off the
eastern shore; near the middle of the western shore a sounding of 40
feet was taken about 50 feet offshore, giving a gradient of 1 in 1-25.
The area of the lake-floor covered by less than 25 feet of water is about
85 acres, or 52 per cent, of the total area of the loch ; that covered by
water between 25 and 50 feet in depth is about 36 acres, or 22 per
cent. ; that covered by water between 50 and 75 feet in depth is about
36 acres, or 22 per cent. ; and that covered by more than 75 feet of
water is about 7 acres, or 4 per cent, of the entire area of the loch.
The flat-bottomed character of the deep basin is well brought out by the
fact that the area between the 25- and 50-feet contour-lines is almost
identical with the area between the 50- and 75 -feet contours. Loch
Turret was surveyed on June 9, 1903, and the elevation of the lake
surface above the sea, measured from the spot-level 1145 on the east
shore, was determined as being 1132 feet. The water in the loch was
high on the date of the survey.

Temperature Observations. — The temperature of the surface water
on commencing the survey at 9 a.m. was 60°'0, and a series of tem-
peratures taken later in the deepest part of the loch gave the following
results : —

Surface ... 60° 8 Fahr.

10 feet ... 59°-o ,,

15 » 54°-0 „

25 » 47°7 „

~>0 »» 44°-8 ,,

75 „ 44° -4 ,,

This series shows a range of temperature from surface to bottom
amounting to 16°-4, there being a fall of 5°-0 between 10 and 15 feet,
one of 6°-3 between 15 and 25 feet, and one of 3° between 25 and 50
feet; the decrease of temperature between 10 and 15 feet was thus
equal to 1° per foot of depth.

Lochan Uaint (see Plate XXXII.).— Lochan Uaine, at the head of
Glen Turret, lies in a corrie; its shores are peat, and the bottom weedy.

THE FRESH-WATER LOCHS OF SCOTLAND. 119

In the middle of the loch towards the north end is a mud islet 2 or 3
feet in length and a few inches above the water. Sir Patrick Keith
Murray tried to drain the loch, but failed, and subsequently a rough
dam was built at the outflow. The burn flowing from Lochan Uaine to
Loch Turret passes among a series of very perfect moraine mounds.
Lochan Uaine is a small shallow loch, about one-seventh of a mile in
length, and covering an area of about 4J acres, with a maximum depth
of 10 feet. The volume of water is estimated at 678,000 cubic feet,
and the mean depth at 3J feet. Nearly 40 soundings were taken, but
some of them have been omitted on the chart for lack of space. The
deeper water occurs near the northern end, to the north-west of the
mud islet; to the south-east of the islet the depth is under 5 feet.
About 80 per cent, of the lake-floor is covered by less than 5 feet of
water. Lochan Uaine was surveyed by request on the same day as
Loch Turret, June 9, 1903; from spot-level, its elevation above the
sea is about 1520 feet. The surface temperature at 2 p.m. was 67°'0.

PondofDrummond (see Plate XXXII.). — The Pond of Drummond,
within the policies of Drummond Castle, near Crieff, is a pretty
artificial loch, well stocked with trout, but strictly preserved; it flows
into the river Earn. It trends east and west, and is two-thirds of a
mile in length, nearly one-third of a mile in maximum breadth, the
mean breadth being one-fifth of a mile, or 31 per cent, of the length.
Its waters cover an area of about 91 acres, and it drains an area four
times greater, or over half a square mile. Sixty soundings were taken,
the maximum depth observed being 12 feet. The volume of water is
estimated at 20,157,000 cubic feet, and the mean depth at 5 feet, or
43 per cent, of the maximum depth. The length of the loch is about
300 times the maximum depth, and 700 times the mean depth. The
Pond of Drummond is, on the whole, very shallow; it is only in the
small narrow portion at the east end that the depth exceeds 8 feet, the
maximum depth of 12 feet having been found in the extreme north-
eastern angle of the loch near the outflow. Nearly 99 per cent, of the
lake-floor is covered by less than 10 feet of water. It was surveyed on
June 18, 1903, but its elevation above the sea could not be determined,
because of inability to find bench-mark. The water in the loch was
very low, the wooden jetty at the boathouse being 2 feet above water.
The temperature of the surface water was 60°-0.

Loch Monzievaird (see Plate XXXII.). — Loch Monzievaird (or
Ochtertyre), within the grounds of Ochtertyre, near Crieff, flows into
the river Earn; it contains pike, carp, and perch, but few, if any,
trout. Its shores are said to be all reclaimed moorland, wooded and
high on the north side, grassy slopes with scattered trees on the south
side. The large island near the north-eastern end of the loch is covered

120 BATHYMETRICAL SURVEY OF

with trees and grass, and is said by Mr. Patrick Murray to be natural ;
the small island to the south is artificial, composed of stones, with a
submerged causeway running eastward to the shore; the island in the
south-western portion of the loch is also artificial, built on piles, and
is said to have been used as a prison. Loch Monzievaird trends in a
north-east and south-west direction, being widest and deepest towards
the south-western end ; there is a central constriction which divides the
loch into two basins. It is over half a mile in length, with a maximum
breadth of one-fifth of a mile, the mean breadth being over one-tenth
of a mile, or 19 per cent, of the length. Its waters cover an area of
about 37 acres, and it drains an area of 1J square miles — an area 27
times greater than the area of the loch. Over 60 soundings were taken,
the maximum depth observed being 39 feet. The volume of water con-
tained in the loch is estimated at 23,905,000 cubic feet, and the mean
depth at nearly 15 feet, or 38 per cent, of the maximum depth. The
length of the loch is 74 times the maximum depth, and 198 times the
mean depth. The depth of water in the central constriction is 7 feet,
with deeper water on both sides, the maximum depth observed in the
north-eastern portion of the loch being 20 feet, while the maximum
depth of the loch (39 feet) occurs in the south-western portion, com-
paratively near the western shore, where the Conalter burn flows in
and the Downie burn flows out. The area of the lake-floor covered by
less than 10 feet of water is about 15 acres, or 39 per cent, of the total
area of the loch; that covered by water between 10 and 20 feet in
depth is about 14 acres, or 37 per cent. ; that covered by water between
20 and 30 feet in depth is about 4 acres, or 12 per cent. ; and that
covered by more than 30 feet of water is about 4 acres, or 12 per cent,
of the entire area of the loch. Loch Monzievaird was surveyed on June
8, 1903 ; its elevation above the sea was not determined by levelling,
but it is evidently slightly under 200 feet since the 200-feet contour
almost coincides with the shore-line. The outflow is controlled by a
sluice, and on the date of the survey the water in the loch was very
low.

Temperature Observations. — Temperature observations taken in the
deepest part of the loch gave the following results : —

Surface ...

68° '0 Fahr

5 feet
10 „ ..

68°-0 „
60° '5

15 „

53° '0

20 ,,

51°'0

36 ,, ...

47° '4

This series shows a range of temperature from surface to bottom
amounting to 20°'6, there being a fall of 7°-5 between 5 and 10 feet,
and a similar fall between 10 and 15 feet — a decrease of 15° in the 10
feet of water, equal to l°-5 per foot.

THE FRESH- WATER LOCHS OF SCOTLAND. 121

Loch Benachally (see Plate XXXIII.). — Loch Benachally, a good
trout loch in the Forest of Clunie, is used by the Blairgowrie Corpora-
tion as the source of the town's water-supply. It flows by the Lornty
burn into the river Ericht, which further on joins the river Isla. Its
shores are of shingle and stones, except at the north-western corner,
where the material brought down by the Craigsheal burn has formed
an extensive flat covered with short weeds. This flat was dry at the
time of the survey, the water in the loch being very low. It is sur-
rounded by low hills covered with heather and grass. It is almost
triangular in outline, the base towards the north-west and the apex
pointing south-east, and is over a mile in length, with a maximum
breadth of over half a mile, the mean breadth being about a quarter of
a mile, or 23 per cent, of the length. Its waters cover an area of about
163 acres, or a quarter of a square mile, and it drains an area of over
3 square miles — an area 12 times greater than the area of the loch.
About 60 soundings were taken, the maximum depth observed being
64 feet. The volume of water contained in the loch is estimated at
177,566,000 cubic feet, and the mean depth at 25 feet, or 39 per
cent, of the maximum depth. The length of the loch is 87 times the
maximum depth, and 220 times the mean depth. Loch Benachally
forms a simple basin, the bottom sloping more or less regularly on all
sides down to the deepest part, which is approximately centrally placed.
The slope of the bottom is in some places rather steep — for instance, off
the northern shore near the north-western angle, and off the southern
shore near the middle, where soundings of 22 feet were taken about 60
feet from the shore, giving a gradient in each case of 1 in 2'7. The
loch is on the whole comparatively deep, very few of the soundings
being under 10 feet. The area of the lake-floor covered by less than
25 feet of water is about 91 acres, or 56 per cent, of the entire area of
the loch; that covered by water between 25 and 50 feet in depth is
about 58 acres, or 36 per cent. ; and that covered by more than 50 feet
of water is about 13 acres, or 8 per cent, of the total area of the loch.
Loch Benachally was surveyed on June 3, 1903, and the elevation of
the surface of the water was determined, by levelling from bench-mark,
as being 1004'9 feet above sea-level.

Temperature Observations. — Temperature observations taken in the
deepest part of the loch gave the following results : —

Surface 57°"2Fahr.

10 feet 55°-8 ,,

15 „ 54°-3 „

20 „ 49°-0 „

*' „ 47°'4 ,

*> , 47° -2 „

•><> „ 47°-0 „

«0 , 46°'8

122 BATHYMETRICAL SURVEY OF

This series shows a range of temperature throughout the 60 feet of
water amounting to 10°'4, the greatest fall being one of 5°-3 between
15 and 20 feet.

Loch Shechernich (see Plate XXXIII.).— Loch Shechernich (or
Bainie), a small loch in Glenshee, situated amid fine mountain scenery,
is a good trout loch, but strictly preserved. It flows by the Allt Mor
into Shee water, thence by the Black water into the river Ericht, a
tributary of the river Isla. Its shores are low and peaty, rising
gradually to the surrounding heather-clad hills. Near the centre of
the loch is an artificial island composed of small stones. Loch
Shechernich trends in an east and west direction, and is nearly half a
mile in length, and one-fifth of a mile in maximum breadth, the mean
breadth being one-seventh of a mile, or 31 per cent, of the length. Its
waters cover an area of about 42 acres, and it drains an area 16J times
greater — an area considerably over 1 square mile. Thirty soundings
were taken, the maximum depth observed being 8 feet. The volume of
water is estimated at 7,364,000 cubic feet, and the mean depth at
4 feet, or 50 per cent, of the maximum depth. The bottom sinks
gradually from the west towards the east end, being covered by less
than 6 feet of water in the western half (to the west of the central
island), while the greater portion of the eastern half is covered by more
than 6 feet of water, the maximum depth of 8 feet having been observed
in three places comparatively close to the east end. The area of the
lake-floor covered by less than 5 feet of water is over 31 acres, or 75 per
cent, of the entire area of the loch. Loch Shechernich was surveyed on
the same day as Loch nan Eun, July 2, 1903. The elevation above the
sea could not be ascertained, but from spot-levels it is probably about
1330 feet. The water in the loch was about its lowest on the date
of the survey, and apparently rises 1 to 2 feet higher. At 6 p.m. the
temperature of the water at the surface and at a depth of 7 feet was in
each case 59°-2.

Auchenchapel Loch (see Plate XXXIII.). — Loch Auchenchapel (or
Auchintaple), in Glenisla, near Inverharity, is an artificial loch made in
1884, and flows by a short stream (Allt na Beinne) into the river Isla;
it is a good trout loch, without pike. It trends in a north and south
direction, and is over one-third of a mile in length, and over a quarter
of a mile in maximum breadth, the mean breadth being over one-
seventh of a mile, or 40 per cent, of the length. Its waters cover an
area of about 35 acres, and it drains an area 5J times greater — an area
of one-third of a square mile. Over 40 soundings were taken, the
maximum depth observed being 17 feet. The volume of water con-
tained in the loch is estimated at 12,669,000 cubic feet, and the mean
depth at 8 feet, or 49 per cent, of the maximum depth. Auchenchapel

THE FRESH- WATER LOCHS OF SCOTLAND. 123

Loch is irregular in outline, and the conformation of the bottom is also
irregular, shallow water extending out into the loch in some places,
while in other places comparatively deep water approaches close to the
shore. The maximum depth of 17 feet was observed near the southern
end of the loch, and a sounding of 15 feet was taken near the centre of
the wide portion of the loch, in close proximity to a sounding of 5 feet.
The diversity in the soundings gives a sinuous character to the 10-feet
contour-line. The area of the lake-floor covered by less than 10 feet of
water is about 22 acres, or 62 per cent, of the total area of the loch.
The loch was surveyed on July 3, 1903, but the elevation above the sea
could not be determined. The water rises about 2 feet above, and
falls about 1 foot below, the level on the date of the survey ; there is a
sluice at the outflow, but it was out of order and disused at the time of
the survey. Temperatures taken at 10 a.m. in the position of the
deepest sounding gave 58°'0 at the surface and 57°'5 at a depth of
16 feet.

Loch of Lintrathen (see Plate XXXIII.). — The Loch of Lintrathen,
from which Dundee draws its water-supply, has been raised in level to
the extent of 22 feet in connection therewith; the water in the loch
was 14 inches below the overflow on the date of the survey, so that the
20-feet contour-line would show approximately the size and position of
the original loch. It receives the drainage from a large tract of the
hilly country to the north, and it flows by the Melgam water into the
river Isla. It is surrounded by gently sloping cultivated ground or
woods, with gravelly margin, except in the north-western angle of the
loch, where the Melgam water and Inzion burn enter, which is shallow
and obstructed by weeds. It is nearly 1J miles in length from south-
west to north-east, with a maximum breadth of three-quarters of a
mile, the mean breadth being nearly half a mile, or 33 per cent, of the
length. Its waters cover an area of nearly 400 acres, or considerably
more than half a square mile, and it drains an area 47 times greater,
or nearly 29 square miles. Nearly 120 soundings were taken, the
maximum depth observed being 70 feet. The volume of water con-
tained in the loch is estimated at 405,207,000 cubic feet, and the
mean depth at 23 J feet, or 34 per cent, of the maximum depth. The
length of the loch is 104 times the maximum depth, and 311 times the
mean depth. The Loch of Lintrathen forms a simple basin, the bottom
sloping down, with few irregularities, to the deepest part, which is
situated in the wide south-western portion of the loch. The maximum
depth of 70 feet was observed to the north of Loch Craigs, considerably
nearer the southern than the northern shore, and the slope of the
bottom off Loch Craigs is evidently very steep, a sounding of 26 feet
having been taken close to the shore. The line of soundings taken
northwards from Loch Craigs shows a slight rise of the bottom towards

124 BATHYMETRICAL SURVEY OF

the centre of the loch, where depths of 54 to 57 feet were found, with
depths exceeding 60 feet to the north and south. The northern portion
of the loch, beyond the narrows at Balnakeilly, is comparatively
shallow. The area of the lake-floor covered by less than 25 feet of
water is about 260 acres, or 66 per cent, of the total area of the loch;
that covered by water between 25 and 50 feet in depth is nearly 100
acres, or 24 per cent. ; and that covered by more than 50 feet of water
is over 40 acres, or 10 per cent, of the entire area of the loch. It was
surveyed on June 25, 1903, and the height of the surface of the water
above the sea was determined, by levelling from bench-marks, as being
674-6 feet.

Temperature Observations. — Temperature observations taken in the
deepest part of the loch gave the following results : —

Surface 55°'5 Fahr.

10 feet 55°-2 „

25 „ 54°-0 „

50 „ 52°-5 „

55 „ 50°'8 ,,

60 „ 48°-2 „

65 „ ... 48°-0 „

This series shows a range of temperature from surface to bottom of
7°'5, the greatest fall being one of 2°-6 between 55 and 60 feet.

Loch of For far (see Plate XXXIII.). — The Loch of Forfar lies
immediately to the west of the town of Forfar, surrounded by cul-
tivated fields. It flows by the Dean water into the river Isla, the
outflow being a broad ditch with no perceptible current on the date of
the survey, the water in the loch being very low. It contains pike,
perch, and trout. It trends almost east and west, and is over a mile in
length, with a maximum breadth of nearly a quarter of a mile, the
mean breadth being about one-seventh of a mile, or 14 per cent, of the
length. Its waters cover an area of about 103 acres, or one-sixth of a
square mile, and it drains an area 14 times greater — an area of over
2 square miles. Over 60 soundings were taken, the maximum depth
observed being 29 feet. The volume of water is estimated at 51,232,000
cubic feet, and the mean depth at 11 J feet, or 39 per cent, of the
maximum depth. The length of the loch is 195 times the maximum
depth and 494 times the mean depth. The Loch of Forfar is peculiar
in conformation, due to the peninsula of Queen Margaret's inch jutting
out into the loch about midway along the northern shore. From the
extremity of Queen Margaret's inch a submerged causeway runs out,
on which depths of 1, 2, and 3 feet were found. The deepest water in
the loch lies to the north and west of the inch and causeway, approach-
ing quite close to the end of the causeway, where a depth of 28 feet
was recorded, the maximum depth of 29 feet being found a few hundred

THE FRESH- WATER LOCHS OF SCOTLAND. 125

feet to the west. To the south and east of the inch depths of 22, 25,
and 26 feet were found, separated from the deep water to the west by
depths of 13 to 16 feet. The 10-feet basin is a continuous area, nearly
three-quarters of a mile in length, following approximately the outline
of the central portion of the loch, the two ends of the loch being com-
paratively shallow, and weeds are abundant off the northern shore at
the east end. The area of the lake-floor covered by less than 10 feet
of water is about 56 acres, or 54 per cent, of the total area of the loch ;
that covered by water between 10 and 25 feet in depth is about 39
acres, or 38 per cent. ; and that covered by more than 25 feet of water
is about 8 acres, or 8 per cent, of the entire area of the loch. The Loch
of Forfar was surveyed on June 26, 1903, and its elevation above the
sea was determined, by levelling from bench-mark, as being 166-3 feet;
when levelled by the officers of the Ordnance Survey in 1861, the
elevation was found to be 170'5 feet above sea-level.

.Temperature Observations, — Temperatures taken in the deepest part
of the loch gave the following results : —

Surface 58°'9 Fahr.

10 feet 58° 3 ,,

15 „ 57°'7 „

20 , ... 56°-0 „

27 ,, 56°-0 „

This series shows a range of temperature from surface to bottom of only
2°-9, the greatest fall being one of l°-7 between 15 and 20 feet.

The particulars regarding the different lochs within the Tay basin
are collected together in the table on next page for convenience of
reference and comparison. Where the elevation above the sea has
not been determined by levelling from bench-mark, the approximate
elevation has, where possible, been indicated within brackets.

From this table it will be seen that in the 59 lochs under con-
sideration 6850 soundings were taken, and that the aggregate area of
the water surface is about 40 square miles, so that the average number
of soundings per square mile of surface is 172. The aggregate volume
of water contained in the lochs is estimated at 151,353 millions of
cubic feet. The area drained by these lochs is 1100 square miles, or
27J times the area of the lochs.

126

BATHYMETRICAL SURVEY OF

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128 BATHYMETRICAL SURVEY OF

NOTES ON THE GEOLOGY OF THE TAY BASIN.

By B. N. PEACH, LL.D., F.R.S., and J. HORNE, LL.D., F.R.S. With
Geological Map (Plate XXXIV.). Published by permission of the
Director of H.M. Geological Survey.

The Tay basin may be divided geologically into two parts, the
boundary between the two being denned by the great fault along the
Highland border which runs from Glen Artney, by Crieff , Murthly, and
Blairgowrie, towards Cortachy and Stonehaven. The area north-west
of this line is mainly occupied by the metamorphic rocks of the Eastern
Highlands, which are pierced by masses of granite, diorite, and other
igneous intrusions, the latter being of special importance in connection
with the history of the glaciation of the region. In the western part of
the metamorphic area, on the lofty peaks of the Black Mount forest,
there is a remnant of the contemporaneous volcanic rocks of Lower Old
Red Sandstone Age, which are so prominently developed in the Lome
plateau. The tract, south-east of the Highland fault, embraces the
lower and smaller portion of the Tay basin. With the exception of a
small patch of Carboniferous strata near Bridge of Earn, the whole of
this tract is occupied by rocks of Old Red Sandstone age.

In connection with the Lake Survey, the area north-west of the
Highland fault is of special interest, as it includes most of the lochs
which have been sounded by the staff. The metamorphic rocks which
floor the greater part of this tract are bounded on their south-east
margin, for a considerable distance, by the great dislocation along the
Highland border. Indeed, the fault-line in places gives rise to a
prominent feature, and the change, in the geological formations on
either side, is indicated by a marked difference in the topography. The
age of the metamorphic rocks of the Eastern Highlands has not
been definitely fixed, and the original sequence of deposition is still
uncertain, but they have been arranged in certain groups, which appear
in a definite order as the observer proceeds northwards from the border
fault.

Apart from the crystalline schists termed the " Moine Series " by
the Geological Survey, which occur in the northern part of the area,
the groups of metamorphic strata met with in the Tay basin are given
in the subjoined table : —

11. Quartzite and quartz-schist with pebbly conglomerate and

boulder bed.
10. Blair Atholl limestone.

9. Black schist with thin limestone bands.

8. Calc-sericite schists and phyllites.

THE FRESH-WATER LOCHS OF SCOTLAND. 129

7. Garnetiferous mica-schists.

6. Loch Tay limestone.

5. Garnetiferous mica-schists of Pitlochry.

4. Hornblende-schists of clastic origin and epidote-chlorite schists

(Green Beds).

3. Schistose grits (Ben Ledi grits and schists).

2. Dunkeld slates.

1. Schistose grits next the Highland fault.

The members of the metamorphic series have been injected by sheets
and bosses of acid and basic igneous materials, which have shared in
the folding and schistosity of the altered sediments into which they
have been intruded.

The distribution of these various groups of altered sedimentary
strata, and the intrusive sheets of basic igneous material (epidiorite
and hornblende-schist), have had an important influence in determining
the trend of the tributary valleys and their surface features. The sub-
divisions given in the above table form sub-parallel belts crossing the
basin in an east-north-east and west-south-west direction, the outcrops
of which have been affected by several powerful faults, to be referred to
presently.

Beginning at the Highland border, we find immediately to the north
of the marginal fault a narrow band of schistose grits, extending from
the river Almond to Birnam wood on the Tay, which may represent the
Leny and Aberfoil grit of the Callander district. Next in order comes
a zone of slate, traceable almost continuously from the forest of Glen
Artney, by Comrie, to a point south of Dunkeld, where it is exposed
in various quarries. The Ben Ledi grits and schists, which, as they are
followed northwards, become more schistose and highly crystalline,
form a belt several miles in width, extending across the basin from the
heights round Loch Earn, north-eastwards by the Almond, Strath
Bran, and the Tay between Birnam Hill and Logierait, and onwards by
Strath Ardle to Kirkton of Glen Isla. Over much of the area where
the metamorphism is not highly developed the schistose grits of this
group give rise to prominent rock features.

The Ben Ledi grits are followed northwards by an important zone
of epidote-chlorite schists (Green Beds), which, in their ultimate stage
of alteration, merge into hornblende-schists that are almost indis-
tinguishable from rocks of this type of igneous origin. They are usually
associated with intrusive sheets of epidiorite that pass into hornblende-
schists, the latter sharing in the folding and schistosity that have
affected the Green Beds. Like the members of this zone in the
Callander region, these epidote-chlorite schists and accompanying sills
of epidiorite form prominent rock features in the landscape, which
have more successfully resisted glacial erosion than the overlying zone of

K

130 BATHYMETRICAL SURVEY OF

garnetiferous mica-schist. On both sides of the valley of the Tay at
Aberfeldy these rocks may be studied, and they appear on the moor-
land between the Tay and Strath Ardle, and eastwards by Kirkton of
Glen Isla, either as isolated patches in the form of outliers, or as more
or less continuous outcrops. Again, towards the south-west, the Green
Beds reappear at intervals on the heights between Loch Tay and Loch
Earn till they are abruptly truncated by the Loch Tay fault.

One of the best-defined zones in the metamorphic series of the
Eastern Highlands is that of the Loch Tay limestone, with its overlying
and underlying garnetiferous mica-schists. In the Tay basin the
members of these groups (5, 6, 7) usually indicate a stage of high
metamorphism, the beds being easily eroded by surface agencies. Save
where deflected by powerful faults, their outcrops are traceable almost
across the basin. From Glen Fernate, at the head of Strath Ardle, the
Loch Tay limestone has been followed south-westwards, by Pitlochry,
along the north slope of the Tay valley at Aberfeldy, to the heights
overlooking Fortingal, where the outcrop has been deflected by the
Loch Tay fault. West of this line of disruption the limestone reappears,
about 4 miles further south, on both sides of Loch Tay (see geological
map), whence it can be traced westwards up Glen Dochart and across
Strath Fillan almost to the slopes of Ben Lui, at the south-west
margin of the Tay basin. Owing to folding, the Loch Tay limestone
and its associated strata reappear to the north of the line of outcrop
just indicated, as, for instance, in Glen Lyon and in the valley of the
Lochay north-west of Killin; and to the south of this line, it is met
with at Lochearnhead and on the Braes of Balquhidder. An important
feature connected with this limestone is the frequent occurrence of a
massive sill of epidiorite in conjunction with it.

Still further north the sub-divisions just described are succeeded by
calc-sericite schists, phyllites, and black schists with thin lenticular
bands of limestone (groups 8, 9), which present lithological characters
that are, as a rule, readily identified. The trend of the outcrop of these
zones has been affected by the north-east and south-west faults which
traverse the basin, and the black schist spreads over a broad area, in
certain localities, by means of sharp isoclinal folds. Taking first the
most southerly outcrop of the calc-sericite schist, phyllites, and black
schist, they are traceable from Ben Vrackie south-west by Faskally on
the Tay, to the Loch Tay fault north of Fortingal. West of this line
of disruption, they have been followed from Glen Lyon, by Ben Lawers,
and across Glen Lochay to the heights above Glen Dochart, where they
terminate in a synclinal fold of the underlying garnetiferous mica-
schists associated with the Loch Tay limestone. Still further west they
reappear and form a broad outcrop stretching from the upper part
of Glen Lyon in a south-south-west direction towards Tyndrum, where
they are again interrupted by a north-east and south-west fault (see
geological map).

THE FRESH-WATER LOCHS OF SCOTLAND. 131

The Blair Atholl limestone has an important development in the
neighbourhood of Blair Atholl, and up the valley of the Tilt towards
the limit of the basin. Sharing in all the folds of the associated
phyllites and black schists (group 9), its outcrop is irregular and
involved. Where these zones appear, in the Tilt, in the Tay, and
Strath Tummel, they generally give rise to softer outlines than the
quartzite which apparently overlies them.

The Perthshire quartzite (group 11) is, perhaps, the most striking
geological sub-division in the metamorphic series of the Eastern
Highlands, from its greater durability and the lofty mountains to which
it has given rise. Along its northern margin the rock is more or less
coarse-grained, due to the presence of pebbles of quartz and felspar,
but this band is repeatedly brought to the surface by means of folding.
An interesting feature of this group is the presence of a conglomerate
or boulder bed with rounded blocks of granite, foreign to the area, the
matrix of which seems to vary with the rock in contact with it. Some-
times appearing as lenticular or boat-shaped masses surrounded by
black schists, phyllite, or limestone, and again as narrow belts traceable
for several miles, the quartzite is always one of the dominant features
of the landscape, occasionally forming lofty peaks, as in Ben-y-Ghlo
and Schichallion.

In addition to the sub-divisions of the metamorphic rocks of the
Eastern Highlands which have just been described, there is a group of
crystalline schists termed the " Moine series " by the Geological
Survey, which have a wide distribution in the north-west part of the
Tay basin. Their lithological characters are remarkably persistent over
wide areas. Consisting mainly of quartzose granulitic schists or fine-
grained gneisses with bands of mica-schist, they represent without
doubt a highly altered series of sediments, the original clastic grains
of which have been destroyed. They form nearly the whole of the area
north of Loch Rannoch, up Glen Garry, and northward of Glen Tilt.

Reference has already been made to the intrusive sheets of basic
igneous rock which appear in association with the Green Beds and Loch
Tay limestone, but others occur in connection with the zones of calc-
sericite schist and black schist. Perhaps the most remarkable example
of the latter is the mass of epidiorite and hornblende-schist on Ben
Vrackie north of Pitlochry, where the altered sediments have been
deflected and bent round the laccolitic intrusion.

The acid igneous rocks which were injected into the sedimentary
series, before the folding and development of schistosity in the latter,
are best represented by the foliated granite of Ben Vuroch, north-east
of Ben Vrackie. On the north-west slope of that mountain, the
sediments, which still retain their original bedding, have undergone
contact alteration, the calcareous shales having been converted into
calc-silicate hornfels.

132 BATHYMETRICAL SURVEY OF

In the central part of the metamorphic area there is a well-defined
line extending from Ben Vrackie south-west by Ben Lawers to Glen
Lochay, which marks the axis of a fan-shaped arrangement of the
folding of the strata. Along this line the axial planes of the folds are
vertical, and on either side they are inclined towards the centre of the
fan. Hence on the south-east side of this central axis there is a
remarkably persistent dip of the folds towards the north-west, while
on the north-west side the general inclination is towards the south-east.
A fine example of the latter is to be found in the river Garry, where
between Blair Atholl and Dalnaspidal the granulitic schists of the
Moine series dip persistently towards the south-east for a distance
of about 15 miles, and yet it is highly probable that the same
bands are repeated indefinitely by means of folding. This remarkable
reduplication of the strata can be clearly demonstrated in the case of
the black schist, limestone, and quartzite groups, where the lithological
types are clearly differentiated from each other. For a distance of
6 miles across the strike, between Ben Vrackie and Glen Tilt, these
groups constantly reappear, the sill of garnetiferous hornblende-schist
being indefinitely repeated with the black schist.

Reference has already been made to the system of north-east and
south-west dislocations which traverse the metamorphic area. Of these,
apparently the most powerful is the Loch Tay fault, which has been
traced from near Blair Atholl, across Loch Tay, Loch Earn, and Loch
Lubnaig, till it is truncated by the fault along the Highland border at
Aberfoil. Further west, and roughly parallel with the foregoing, comes
the line of disruption which extends from Loch Garry across Loch
Rannoch and the valleys of the Lyon, the Lochay, and the Dochart
towards the Braes of Balquhidder. Again, from Tyndrum another
dislocation has been followed north-east by Loch Lyon and the west
margin of Loch Rannoch in the direction of Loch Ericht. Finally, in
the north-west part of the basin there is a line of fracture running along
Loch Ericht and Loch Laidon, which is roughly parallel with the Loch
Tay fault. In the case of the Loch Tay, th« Loch Garry, and the Loch
Lyon dislocations, the downthrow has been on their western side; in
other words, on that side the outcrops of the sedimentary bands and
epidiorite sills have been shifted further to the south by each fault in
turn.

Within the metamorphic area, as already indicated, there are
various masses of igneous rock which are later than the folding and
foliation of the crystalline schists, and have been referred to the newer
granite intrusions of the Highlands. Of these, the most important is
the large mass of diorite on the Moor of Rannoch, which stretches
northwards to Loch Ericht and west towards Loch Treig, boulders of
which have been carried far during the glaciation of the region. Other
masses appear on both sides of Loch Ericht, in Glen Tilt, on the lofty

THE FRESH -WATER LOCHS OF SCOTLAND. 133

plateau north of that valley, and far to the south in Glen Lednoch
between Comrie and Loch Tay. Several of these igneous intrusions
consist partly of diorite and partly of granite, the more basic type being
erupted prior to the more acid.

At the western margin of the basin on the lofty peaks of the Black
Mount forest there is a terraced plateau of contemporaneous igneous
rocks of Lower Old Red Sandstone age, pointing to the former
extension of this volcanic series, the distribution of which is of
importance in connection with the glaciation. These are pierced by
plutonic rocks (granite), which have produced a certain amount of
contact alteration in the lavas.

In the lower part of the basin of the Tay, which is almost wholly
occupied by Old Red Sandstone, both the lower and upper divisions of
that system are represented. The Lower Old Red Sandstone has by
far the greater development, being divisible into a lower volcanic series
and an overlying group of sandstones, conglomerates, and marls. Two
great flexures cross the basin in a north-east and south-west direction,
roughly parallel with the fault along the Highland border. One of
these flexures forms a broad arch, exposing a great series of contem-
poraneous volcanic rocks in the Ochils and the Sidlaws ; the other forms
a great trough, in line with the valley of Strathmore, containing the
highest members of this division in the basin of the Tay. The anti-
clinal fold is prolonged far to the north-east into Forfarshire and
Kiiicardineshire, where sandstones and flags appear in the crest of the
arch. In the Ochils the total thickness of lavas, tuffs, and agglomerates
in the north limb of the fold is about 6000 feet, and they were probably
deposited on a gradually sinking area ; nevertheless, some of the volcanic
cones may have ultimately appeared above the level of the water and
become subaerial. Rising out from underneath the overlying sand-
stones and marls, along the Highland border, the volcanic series again
appears, though in a very attenuated form, consisting of andesitic lavas,
which are associated with coarse conglomerates containing pebbles of
volcanic rocks. Indeed, the lavas, conglomerates, and sandstones occur
on the north side of the fault at Blairgowrie, and again at Crieff, where
they rest unconformably on the metamorphic rocks. The broad tract
of low ground between the Sidlaws and the Highland border has been
carved out of the softer sandstones and marls overlying the volcanic
series. The river Isla, when it enters the area occupied by this
overlying sedimentary series, is deflected towards the south-west till it
joins the Tay.

The long interval which elapsed between the Lower and Upper Old
Red Sandstone periods was marked by great denudation of the members
of the lower division of that system. The strata were thrown into
anticlinal and synclinal folds, the axes of which are roughly parallel
with the trend of the fault along the Highland border. And further,

134 BATHYMETRICAL SURVEY OF

along the crest of the arch, the higher members of the lower division
were worn away, and the volcanic rocks were laid tare, before the
Upper Old Red Sandstone was deposited. The members of the upper
division occur near Bridge of Earn, and extend beneath the estuary of
the Tay and the Carse of Gowrie to near Dundee. Between Forgan-
denny and Bridge of Earn, the basement beds are found resting
unconformably on the denuded Lower Old Red Sandstone volcanic
rocks, where fragments of the latter occur in the breccias. On both
sides of the estuary of the Tay, however, the Upper Old Red Sandstone
is brought into conjunction with the volcanic series of the lower division
by two parallel faults. The members of the upper division are
composed mainly of friable brick-red sandstones and marls, which have
yielded near Errol fine specimens of the genera of fishes characteristic
of this division.

Reference has already been made to the fact that a small patch of
Carboniferous rocks appears about half a mile to the south of Bridge of
Earn, which are brought into conjunction with the Lower Old Red
volcanic rocks to the south by means of a fault. The strata consist of
blue clays and shales, sandstones, and calcareous bands belonging to
the Cementstone group. Small though it be, this remnant is of great
importance in proving the former extension of the Carboniferous rocks
over the lower part of the Tay basin, from which it has been almost
wholly removed by denudation.

The existing valley system of the basin of the Tay furnishes
admirable examples of the influence of geological structure in
determining the direction of the water drainage. The upper part of
the Tay itself, and many of the tributaries within the metamorphic
area, flow approximately in the direction of the strike of the crystalline
schists. The massive Ben Ledi grits, the Green Beds, the sills of
epidiorite and hornblende-schist, and the Perthshire quartzite have
each had a powerful influence in the development of the prominent rock
features of the region. Where these occur in association with zones of
mica-schist and phyllite, they have more successfully resisted erosive
action, and have given rise to rocky barriers or precipitous escarpments,
thereby contributing to the formation of gorges, and in some cases of
rock-basins.

The evidence relating to the glaciation of the Tay basin leads to the
conclusion that, during the climax of the Ice age, the region must have
been covered with one continuous sheet of ice, the movement of which
must to some extent have been independent of the existing valley
system. Where the rocks have been able to retain the striae, the latter
have, been found up to elevations of 3000 feet, showing that the highest
mountains were over-ridden by the ice. This stage was followed bv

*/ o J

a period of confluent glaciers, when the ice streamed over passes
connecting adjoining valleys, leaving in its track lines of moraines.

THE FRESH- WATER LOCHS OF SCOTLAND. 135

Finally, there is the phase of corrie glaciers, when the glacial detritus
was borne for no great distance from the local centres of dispersion.

During the maximum glaciation, the ice-shed lay round the north-
west margin of the Tay basin, from the mountains beyond Rannoch
Moor, by Ben Alder west of Loch Ericht, eastwards to the watershed
separating Glen Garry from the tributaries of the Spey and the Dee.

Beginning in the western part of the basin, with the lofty watershed
between the head of Glen Lyon and Glen Lochay, in the Mamlorn
forest, striae are found at intervals along this ridge for a distance of
3 miles, at elevations which in some cases vary from 2700 to 3000 feet,
trending E. 20° to 30° S. Further east, about 3 miles north of Killin,
on Creag-iia-Caillich at a height of 2250 feet, the direction is about
south-south-east. Again, to the west of Ben Lawers, the ice-markings
point S. 40° E. about the 2000-feet level. Proceeding northwards to
the dividing line between Glen Lyon and Strath Tummel, the evidence
is no less remarkable, for on Schichallion, at an elevation of 3000 feet,
the trend is E. 30° S. Still further north, on Beinn a' Chuallaich — a
high mountain between Glen Erichdie and Kinloch Rannoch — -the
striae point S. 30° E. at a height of 2700 feet. Again, on Ben Vrackie,
about 3 miles north of Pitlochry — -a mountain which is glaciated to
the top — the trend is east-south-east. Similar conclusive evidence
is obtained on the dividing ridge that stretches eastwards from
Schichallion towards Pitlochry and separates Strath Tummel from
the upper course of the Tay between Aberfeldy and Logierait. Part
of this ridge is composed of the Perthshire quartzite, the glaciated
surfaces of which show finely preserved striae, the direction varying
from E. 20° S. to E. 45° S. On one of the prominent peaks of this
ridge — Ben Eagach — south of Loch Tummel, ice-markings are found on
the top at a height of 2250 feet, which point E. 35° S. Further south,
on the dividing ridge between Strath Bran and the valley of the
Almond, on Meall nan Caoraich, the direction is E. 30° S., close to the
2000-feet contour-line. Additional instances might be given from the
mountainous region within the metamorphic area, but the above
examples establish the conclusion that during the maximum glaciation
there must have been a movement of the mer de glace independent of
the valley system in an east-south-east or south-easterly direction.

During the great extension of the ice, on the broad plateau of the
Moor of Rannoch the ice seems to have radiated partly towards the
east-south-east or south-east, and partly towards the south-west in
the direction of the Tulla and Glen Orchy (see geological map).

The evidence obtained from the dispersal of the boulders is no less
remarkable, for in some cases they have been carried far from their
parent source, and over lofty cols. The boulders of diorite or horn-
blendic granite from the Moor of Rannoch have been found in Strath
Tummel, in Glen Lyon, in Strath Fillan, in Strath Tay, and across the

136 BATHYMETRICAL SURVEY OF

watershed into Glen Almond. Again, all along Strath Fillan, Loch
Tay, and Strath Tay, boulders of the Perthshire quartzite, black
schist, limestone, and calc-sericite schist have been carried several miles
to the south of the various belts from which they were derived. Of
course, in many of these instances, the boulders may have been dis-
tributed during the later glaciation. On the slopes of Ben More (3843
feet), which is composed of grits of the Ben Ledi group, blocks of calc-
sericite schist occur that have been carried from the hills to the
north-north-west in the direction of the. Mamlorn forest. Confirmatory
evidence is furnished by the dispersal of the stones in the boulder clay —
a deposit formed during the great extension of the ice. Within the
metamorphic area, sections of boulder clay occur up the Tay valley as
far as Loch Tay, in the valleys of the Tummel and the Garry as far as
Struan, and in Strath Bran from Amulree to Dunkeld. Outlying
patches are found also at the east end of Loch Rannoch and round
Loch Tummel.

After the stage of the great ice-sheet, there followed a period of
confluent glaciers when the ice was still thick enough to stream over
passes connecting adjoining valleys, as, for instance, over some of the
cols between Glen Lyon and Glen Lochay, between Glen Lyon and Loch
Tay, and between Glen Lochay and Glen Dochart, between the upper
course of the Tay and Strath Bran, and between Loch Tay and Glen
Almond. Again, the glacier which moved eastward from the high
mountains in Black Mount forest and at the head of Glen Coe and Glen
Etive was deflected southwards, part of it flowing into Glen Orchy, and
part into Strath Fillan. The numerous groups of moraines, frequently
showing a terraced arrangement along the hill slopes, indicate the great
development of the later glaciation. Fine examples of the local
dispersion of moraines are to be found in the neighbourhood of the
Black Mount forest and the mountains round the head of Glen Etive
and Glen Coe. The debris of Old Red Sandstone volcanic rocks have
been traced in the moraines eastwards from the Black Mount forest to
the drift-covered plateau at Loch Ba.

Within the Tay basin by far the larger number of the lochs lie in
the midst of drift deposits, most of which are of 110 great size, and are
comparatively shallow. In the southern part of the Moor of Rannoch,
along the river Ba and its tributaries, in Allt Lochain Ghaineamhaich,
and on the drift plateau, about twenty-five lochs occur in the midst of
morainic drifts. Numerous examples of this type occur in other parts
of the basin.

Again, several lochs, some of which are of considerable size, lie
along lines of displacement, or fault-lines, for which reason they need
not now be discussed. For example, Loch Ericht and Loch Laidon are
situated on one line of disruption which has been traced over a con-
siderable distance in the eastern Highlands. Loch Garry, at the head

THE FRESH- WATER LOCHS OF SCOTLAND. 137

of Glen Garry, and Loch Lyon, near the head of Glen Lyon, likewise
occur along lines of fault. In each of these cases, the long axis of the
loch coincides with the course of a more or less powerful dislocation,
which has been traced for miles.

The following instances might be discussed in relation to the
question of the glacial origin of rock basins : Loch Rannoch, Loch
Tummel, Loch Tay, Loch Earn, Loch lubhair, and Loch Dochart. Of
these, the first four have been previously described by our colleague,
Mr. J. S. Grant Wilson, in the Scottish Geographical Magazine for
May, 1888, in connection with the soundings made by him in the
course of the geological survey of the district. It is not necessary,
therefore, to give in detail the evidence in support of the view that
these lochs, with the exception of Loch Tay, have been eroded by ice-
action. His soundings have been, as a rule, confirmed by Sir John
Murray and his staff.

Loch Raimoch is a fine instance of a rock basin, for though, at the
lower end, the river Tummel, which issues from the loch, flows along
an alluvial flat for a distance of 3 miles as far as Dun Alastair, a rocky
barrier appears at the latter point in the river and on the hill slopes.
Near the foot of the loch, on either side of the valley, there is a
prominent mass of high ground, culminating in Schichallioii (3547 feet)
and Beinn a' Chuallaich (2925 feet). The streams draining this high
ground to the north and south have silted up the loch at the lower end,
and have produced the long stretch of alluvium between Kinloch
Rannoch and Dun Alastair. The longitudinal section of Loch Rannoch
shows that the loch gradually deepens from the west margin towards
the centre and lower end. The soundings further show that between
the mouth of the Dall burn and the foot of the loch there are three
small basins, each over 400 feet in depth. The deepest sounding — 440
feet — is in the centre of the largest and most easterly of these three
basins, and within 2 miles of Kinloch Rannoch. On referring to the
geological map it will be seen that the Loch Garry fault crosses Loch
Rannoch near Dall in a S.S.W. direction; and, notwithstanding the
fact that the downthrow side of this fault is towards the west, yet the
deepest sounding is found on the upthrow side.

Loch Tummel is another typical example of a rock basin, the rocky
barrier appearing in the stream and on the hill slopes at Allean House,
about a mile below the mouth of the lake. For several miles down-
stream, as far as Faskally, the Tummel cuts through solid rock,
composed mainly of the Perthshire quartzite, with bands of black
schist. This loch has had originally a greater extension westwards,
for it has been silted up by alluvial matter deposited by the streams.
It is about 2£ miles long, and the soundings show that it forms three
separate basins of no great depth, the deepest sounding of the western
basin being 128 feet; of the central, 119 feet; of the eastern, 99 feet.

138 BATHYMETRICAL SURVEY OF

Where these slopes and barriers appear, streams enter the lake from
the south, which have given rise to cones projecting for some distance
into the loch. It is probable, however, that they may be formed partly
of solid rock. Judging from the evidence round the sides of Loch
Tummel, the floor of that loch consists mainly of black schist, with
infolds of the lower part of the quartzite.

Loch Earn may be described as the best instance of a typical rock
basin within the catchment area of the Tay. Upwards of 6 miles long
and about three-quarters of a mile broad, the soundings show that it
is a simple basin. The deepest sounding — 287 feet — occurs about half-
way down the loch. The Loch Tay fault crosses the lake about a mile
from the upper or western end; and along its course there is a small
basin, the greatest depth of which is 240 feet. West of this fault, the
floor of the loch is composed of the Loch Tay limestone and the under-
lying garnetif erous mica-schists ; east of it, for some distance, the lake
lies obliquely across the strike of the schists overlying the Green Beds
and the Green Beds themselves; while at the foot of the loch the Ben
Ledi grits appear as a rocky barrier crossing the valley at St. Fillans.

Lochs lubhair and Dochart may be cited as further instances of rock
basins. Originally forming one sheet of water, they have been isolated
by alluvial matter brought down by the stream that drains the great
corrie west of Ben More. The deepest sounding of Loch lubhair — 65
feet — is near the foot. Roches moutonnees appear in that lake, both
about the middle and near the foot. Loch Dochart is being rapidly
silted up; indeed, it must formerly have extended for 3 miles up the
valley of Strath Fillan. The deepest sounding of Loch Dochart is
11 feet.

Further down Glen Dochart there is a strip of alluvium about 5
miles long, between Luib station and Easter Lix, which may probably
represent a silted-up rock basin.

Loch Tay presents certain features which differentiate it from the
rock basins already described. There is no rocky barrier close to the
lake; the Loch Tay fault runs along the course of the lake for a
distance of 5J miles from Ardeonaig to Stronfearnan ; the greatest
depth, which is 508 feet, lies on the downthrow side of this dislocation ;
and finally there is a basin 12 miles long, the whole of which is below
the level of the sea. The first appearance of solid rock in the bed of the
Tay is north of Grandtully castle, about 8 miles below the foot of the
loch, where mica-schists appear, belonging to the group of the Ben
Ledi grits. For a distance of 1J miles below this point to near
Ballinluig village the river flows at intervals over rocky ledges. There
can be no doubt that the deflection of the original valley of the Tay
between Ardeonaig and Stronfearnan was due to the Loch Tay fault,
whereby the Loch Tay limestone and associated schists on its western
side were brought into conjunction with the intrusive igneous masses

THE FRESH- WATER LOCHS OF SCOTLAND. 139

of Tomnadashan and Beinn Bhreac. The soundings show that the
deepest part of the basin, which is bounded by the 400-feet contour-
line, lies along the course of this fault. Under these circumstances,
Loch Tay cannot be regarded as a typical example of a rock basin.

The other rock basins, however, seem to us to furnish strong
evidence in support of the theory that they have been eroded by ice-
action.

BIOLOGY OF THE LOCHS OF THE TAY BASIN.
By JAMES MURRAY.

While it was not compatible with the bathymetrical work of the
Lake Survey to study in detail the biology of the lochs, it has been
customary to make collections of the plankton of each loch, a coarse and
a fine net being used in each case. It is thus possible to compare only
the biology of the open water of the different lochs. The number of
species living in the open water is not very great, and does not vary
in different lochs so much as might have been expected. The fauna of
the shallower lochs is usually much richer than that of the deeper ones,
owing to the occurrence in them of many species which in larger lochs
would be confined to the shore region. Even thus limited, it is found
that the lochs differ sufficiently from one another to render a com-
parative review of them of much interest. Each loch has a distinct
character, which, notwithstanding a considerable amount of seasonal
variation, is pretty constant.

A small number of animals and plants occur so constantly in the
open water of all our lakes, large or small, that they mainly determine
the character of the plankton of this pelagic region. They are so
generally present that the absence of any one of them is occasion for
remark. The most important of them are — Diaptomus gracilis, Cyclops
strenuus, Daplmia lacustris, Bosmina obtusirostris, the Rotifers
('uuochilus (two species), Anurcea cochleare, and Notholca longispina,
and the Diatom Asterionella gracillima. These are found at all seasons.
In the summer, Holopedium, Leptodora, Bythotrephes, and Polyphemus
are as generally distributed.

Only less common are Asplanchna priodonta, Polyarthra platyptera,
Pendinium tdbulatum, Ceratium Jiirundinella, Mallomonas. Some
Desmids, mostly of the genus Staurastrum, but including also species of
Mirrasterias, Xanthidium, and Closterium, are generally present. The
Rotifers Floscularia pelagica and Notops pygmceus are of frequent
occurrence. Although all of those species may be present in most of
the lochs, the varying proportions in which they occur in the plankton
give rise to great differences of character in the lochs. Other species of

140 BATHYMETRICAL SURVEY OF

Diaptomus, Daphnia, and Bosmina are occasionally found, but the
species included in the preceding list are so much more common, that
when the generic name only is mentioned it will be understood that
the common species is referred to.

This small association of animals and plants constitutes what may
be called the lacustrine type of plankton. A not very dissimilar
association is found in small ponds, but the species for the most part
are different. The Diaptomus may be D. castor, the Daphnia D. pulex,
the Bosmina B. cornuta; Rotifers and Algae will be more abundant and
varied, and there will probably be some Ostracodes. It might have
been expected that the shallowest lochs would have had a plankton of
the pond type, but it has been found that even the smallest lochs
surveyed had the plankton distinctly lacustrine. A few nearly or quite
stagnant lochans showed a slight approach to the pond type in the
presence of Bosmina cornuta and Volvox and in the abundance of
Rotifers and Algae.

The remarkable variations of the loch trout, which have so much
puzzled naturalists cannot be touched on here, but parallel cases are
found among the smaller animals. Diaptomus gracilis varies remark-
ably in colour, and is usually constant for each loch, and several other
Entomostraca vary greatly in size and form; chief among these is
Daphnia. The typical lacustrine form of this genus, which will be
referred to as Daphnia lacustris, has an evenly rounded head with a
depression on the line of the forehead marking off the brow from the
beak. Where this depression is obliterated the head of the animal has
a very different appearance, resembling that of a parrot. The form
differing most from the typical Daphnia lacustris is that in which
the head is produced upwards into a sort of peak or helmet. For
convenience, this form will be referred to as Daphnia galeata, though
it is doubtful if the points of difference are of specific value, and
intermediate varieties are found.

After Daphnia, the species which varies most is Bosmina
obtusirostris. The typical lake-form has a short mucro at the posterior
angle of the valves. It varies much in size and in colour, being usually
hyaline, but sometimes purple, or rarely orange and purple.

During its season Holopedium, from its large size, is very conspicuous
in those lochs in which it occurs. It is frequently so abundant that it
chokes up the nets in a short time, and makes it impossible to get a fair
proportion of the other animals present. It appears in some lochs as
early as May, and continues till August.

Commonly a single organism, usually vegetable, will so increase in
a loch as to form what the Germans call a " Wasserblut." The Algae
Clathrocystis, Oscillaria, Botryococcus, Anabcena, and Volvox are among
those which most frequently increase to this extent, but almost any of
the smaller organisms, as Diatoms, Rotifers, or Protozoa, may on

THE FRESH- WATER LOCHS OF SCOTLAND. 141

occasion do so. Asterionella, Xotholca longispina, Asplanchna
priodonta, Ceratium hiriitidhiella, and even on one occasion the rather
uncommon Rotifer Dinocharis Collinsii, have been observed to form a
" Wasserblut " in the shallower lochs.

The abundance of certain species in a loch on a single visit may be
exceptional or temporary ; the small lochs may vary greatly at different
seasons. It is believed that, except for the seasonal appearance of
certain species which are known to live for only a few months of the
year, a loch is pretty uniform in character throughout the year. This
is known to be the case with the large lochs and with some small ones.

The points to which attention will be called in reviewing the biology
of the Tay lochs will be — the abundance or scarcity of life on the
whole; the preponderance of one or a few species in each loch; the
abundance of an animal or plant that is usually scarce; the absence
or scarcity of some very common species.

The lochs of the valley of the Earn differ much in size and physical
conditions, so that they might be expected also to differ much in their
biology. There is one great lake, Loch Earn, two hill lochs, Turret
and Uaiue, the latter at a great elevation, one deep but stagnant pond,
and one shallow artificial dam.

Loch Earn. — The only abundant organism was Diaptomus gracilis,
which was bright red in colour. There was almost no life at the
surface, the Diaptomu* being in myriads at a depth of 40 or 50 feet.
The loch was rather remarkable for the scarcity of common lacustrine
species. Bythotrephes was somewhat frequent; Polyphemus, Cyclops
strenuus, and Bosm-ina obtusirostris were present, but not plentiful.
Daphnia was very rare, only one example being seen. Smaller
organisms were almost entirely absent, except for a few examples of
the two commonest pelagic Rotifers : Anurcea cochleare and Xotholca
longispina, and some unicellular Algae.

Loch Turret. — This was one of the lochs where Holopedium filled
the net with a slimy mass, and rendered it difficult to catch anything
else. Diaptomus y radii* , Daphnia (typical D. lacustris), Asterionella,
Pfridinhun tahulatum were noted.

Lochan Uaine. — This little shallow tarn, in a corrie at a considerable
elevation, had nothing remarkable in its pelagic life. Diaphanosoma
brachyuruin was most numerous ; Diaptotnus yradlis, of a brown colour,
and Polyphemus were common. Only a few examples of Daphnia
larustrts and Holopedium were seen.

Loch ^[<>n:ie^clird (or Ochtertyre). — This loch, though fairly deep,
was almost stagnant at the time it was visited. As might be expected
from this and from the very high surface temperature, life was abundant
and varied. The collection was green from the abundance of Volvor.
Bosmina cor nut a, Daphnia lacustris, Diaptomus yracilis (of a brown

142 BATHYMETRICAL SURVEY OF

colour), Ceratium hirundinella, Asplanchna, Anurcea cochleare,
Anabcena were among the most abundant organisms. Many others
were present in smaller numbers.

Drummond Pond. — This is a shallow and nearly stagnant artificial
pond, and many species were plentiful in the water. Daphnia
lacustris was most numerous. Many males and females carrying
ephippia were present. Other abundant species were Ceriodaphnia
(some with ephippia), Anurcea cochleare, Conochilus, Asplanchna,
Notops pygmceus. Volvox was scarce. The beautiful Rhizopod Difflugia
corona was seen.

The lochs of Strath Bran, though completely isolated one from
another, and draining by different streams into the Bran, are fairly
comparable one with another, being all, with the exception of Loch
Freuchie, hill lochs of small size, lying at considerable elevations.

Loch Freuchie. — This was one of the lochs where Holopedium for
the time being abounded to the exclusion of everything else. Only a
few individuals of Diaptomus gracilis (brown in colour) were seen.
Hardly any small organisms were noticed.

Loch Fender. — Life was abundant, but few species were present.
The most numerous animals were Diaptomus (pale brown), Notholca
longispina, Daphnia (parrot-shaped head), Bosmina longispina, and
Peridinium tdbulatum. Holopedium was not seen.

Loch Hoil.- — Life was very abundant. The commonest animals were
Holopedium, Diaptomus gracilis, D. Wierzejskii (blue, red, or red and
blue), Daphnia, and Asplanchna.

Loch na Craige. — Animals of many species were present, but only
four were plentiful — Diaptomus gracilis (blood-red), Bosmina ob-
tusirostris (of large size), Daphnia lacustris (very large), and Conochilus
unicornis.

Loch Kennard. — Some seven or eight species of animals were
common in the loch, but Diaptomus predominated. D. gracilis and
D. Wierzejskii were both present. Blood-red individuals of both species
occurred, and D. Wierzejskii was also seen of the usual blue colour, or
red and blue. Holopedium, Notholca longispina, and Asplanchna
priodonta, and the somewhat rare crustacean Latona setifera, were
numerous.

Loch Skiach. — The characteristic animals were Holopedium,
Daphnia lacustris (very large), Bosmina obtusirostris (very small,
purple). Gammarus pulex of large size, and orange colour, was found.
A few examples of Bosmina were large and brightly coloured, orange
and purple.

Loch Tay. — Comparing Loch Tay with Loch Rannoch, it is found
that the plankton differs in several important particulars. Besides the
common Diaptomus gracilix, there was another species, D. Wierzejtkii ,

THE FRESH- WATER LOCHS OF SCOTLAND. 143

pretty common in the loch. This is a larger species, usually dark blue
in colour. It is a northern species, of general occurrence over the
north and west of Scotland, but hardly known south of Loch Tay.
Daphnia was always very scarce. Desmids of the genera Staurastrum
and Arthrodesmus were more numerous than is usual in great lakes.
As in Loch Rannoch, skeletons of Clathrulina were abundant.

Lochs lubhair and Dochart. — Both these lochs, being very shallow,
had, at the time they were visited, in addition to the usual pelagic
species of Diaptomus, Daphnia, and Bosmina, several species in
abundance which are not truly pelagic. Chydorus sphcericus, Alonopis
elongata, and Alonella nana were as numerous as the pelagic species.
Rotifers and Protozoa, especially Rhizopods, were more varied than
usual.

Loch Essan. — Life was abundant and varied. Daphnia was of three
forms — large typical Daphnia lacustris with rounded head, smaller
with tall helmet (D. galeata), and an intermediate form. Diaptomus
gracilis, some dark brown, some hyaline, Polyphemus, Diaphanosoma
brachyurum, Bosmina obtusirostris, and water-mites (Hydrachnidae),
which do not usually occur in the open water, were all common.

Loch Breaclaich. — This loch was quite unusual from the great
numbers of a Rotifer, Asplanchna priodonta, which formed a
" Wasserblut," appearing as a great slimy mass in the net.
Diaptomus gracilis (hyaline), Cyclops (dark red), and Diaphanosoma
brachyurum were seen.

Loch na Lairige. — The characteristic organisms were Bosmina
obtusirostris (large dark brown, and purple) and a species of Conochilus.
Daphnia galeata (with tall helmet), Polyarthra, and Diaptomus
gracilis (pale, immature) were frequent. A few dark red Diaptomus
gracilis, Sida crystallina, and Bythotrephes were also present.

Loch Lyon. — The biology of this loch was notable for its unusual
richness. Most abundant were Diaptomus gracilis (pale yellow),
Bosmina obtusirostris (with somewhat long spine), Cyclops strenuus (of
large size), and Rotifers of many species. Larvae of Diaptomus were
exceedingly numerous.

Lochs Daimh and Giorra. — These two lochs are so nearly alike in
size and so close together, being connected by a river, that they might
be expected to resemble one another in their biology, but they were
found to differ greatly. In Loch Daimh, Holopedium was abundant,
but very young. Diaptomus gracilis (hyaline, with dark brown eggs)
was numerous, and the larvae still more so. Nothing else was found in
any numbers. Loch Giorra, on the other hand, had half a dozen
common species — Diaptomus gracilis (pale yellow), Cyclops strenuus,
Daphnia lacustris, Bosmina obtusirostris, Dinobryon, and Tabellaria
(two species). Holopedium was not seen.

144 BATHYMETRICAL SURVEY OF

Loch Derculich. — The characteristic animals were Diaptomus
(brown), Daphnia lacustris (with parrot-shaped head), Bosmina ob-
tusirostris (with long beak), Notholca longispina, and Dinobryon.

Loch Scoly. — The most abundant animals were Daphnia lacustris,
Diaptomus gracilis (dark brown, mostly immature), Conochilus volvox,
Bosmina obtusirostris (small), and Peridinium tabulatum.

Loch Rannoch. — The plankton of Loch Rannoch may be fairly
taken as" the type of all the large Scottish lochs. Almost every one of
the species included in the list of the lacustrine organisms was found in
it, and there was nothing in it not given in the list. Of the Entomos-
traca, Bosmina was the most abundant. Skeletons of the Rhizopod
Clathrulina elegans, though this is not a pelagic animal, were always
found in it. The biology of the littoral region of the loch has
been studied with some care by Mr. D. J. Scourfield and others,
but as this region has not been studied in the other lochs of the
system, it is thought better not to enter into the details of it
here.

Loch Ba. — Most of the common pelagic animals were not seen, while
many species belonging rather to the shore (or littoral) fauna were
numerous, as Eurycercus lamellatus, Acroperus harpce, Alonella nana
and A. excisa, Alona affinis and A. guttata, and Chydorus sphccricus.
Many Rhizopods were observed, as well as mites and Ostracodes.

Loch Laidon. — Only the Entomostraca of this loch were studied
by Mr. D. J. Scourfield. The species were all the same as in
Loch Rannoch. No collections were made of the other groups of
animals.

Lochan Sron Smeur. — Notwithstanding the high elevation and the
early season at which it was examined, this loch was found to be
exceptionally rich in both animals and plants, particularly in Rotifers,
Rhizopods, and Desmids. Holopedium was here seen unusually early
in the season. Besides the ordinary pelagic animals, Diaptomus,
Daphnia, Bosmina, &c., Latona setifera was present.

Loch Bhac. — The commonest animals were Diaptomus gracilis (red),
Bosmina obtusirostris (with long beak), Daphnia lacustris, Diaphano-
soma brachyurum. Among the Rotifers was the brilliant red and blue
Notops pygmceus, and the curious Desmid Micrasterias Wallichii was
present.

Loch Con. — Entomostraca were few, and Algae more numerous
than usual. The commonest animal was Bosmina obtusirostris (small).
Diaptomus gracilis (some large, yellow, others red). The Rotifer
Notops pygmceus was unusually large.

Loch Tilt. — In common with a few other lochs, usually lying at
considerable elevations, the only common animal was Diaptomus
gracilis, so bright red in colour that the net, when taken up, seemed
filled with blood. Hardly anything else was seen.

THE FRESH- WATER LOCHS OF SCOTLAND. 145

Loch Moraig. — Entomostraca were here scarce, and Protozoa and

Algae abundant. The commonest organism was a form of Ceratium

'tdinella, which was so abundant as to constitute a " Wasserblut."

Loch Broom. — This shallow, marshy pool, with Menyanthes growing
almost everywhere, yet had a quite ordinary lacustrine fauna, including
Diaptomus (dark brown), Daphnia lacustris (very large), Cyclops
strenuus (large hyaline), Bythotrephes . Conochilus was much the
commonest animal. An unusual form of Ceratium hirundinella,
having both the median spines long, occurred.

Loch Or die. — The most abundant animals at the time this loch was
visited wereHolopedium, Daphnia (parrot-shaped head), and Diaptomus
(hyaline). Bosmina of two forms was found — B. obtusirostris (small)
and B. longispina.

Loch nan Eun. — The highest loch in the Tay system visited. The
predominant animal was Diaptomus yracilis (blood-red); Daphnia
hu-u.it r is (very large), Bosmina obtusirostris, and several species of
Desmids, notably Staurastrum arctiscon, were present in some numbers.
There was a scarcity of smaller organisms.

Loch Shechernich. — The water was turbid from the abundance of
life. The most conspicuous examples were Diaptomus (dark red, red
and yellow, red and blue, or all blue), probably D. Wierzejskii,
Daphnia (parrot-shaped head), Bosmina (very large, purple), Xotholca
longispina, and Polyarthra. Asterionella was of a smaller size than
usual. Numbers of a small yellow water-mite were seen.

Loch Auchenchapel. — Ceratium hirundinella formed a " Wasser-
blut " in the loch at the .time it was visited. Other common animals
were Bosmina obtu*iro*tris, Daphnia lacustri-s (small), Diaptomus
(reddish), f'onocliilus.

Loch of Lintrathen. — The water was very clear, and organisms
sparingly distributed. Daphnia lacustris (large) and Diaptomus
y rat: Hi* (hyaline) were the only animals at all common.

Lnrh BtnachaUy. — Hnlopedium was common on the surface, but not
below. Diaptomus t/racilis (brown, mostly immature) and Daphnia
(large) were most abundant. Bosmina was scarce.

Long Loch. — Very few animals were present, the commonest being
f(irtt*tris, Diaptomus yracilis (hyaline), and Conochilus.

Pitlyal Lorji. — This differed from most lochs visited about the same
time in the general scarcity of life, especially of Entomostraca. It was
one of the few lochs in the system where Bosmina cornuta took the place
of the common B. obtusir<>*fri«. There was a " Wasserblut " of a pale
filamentous Alga. Volvo/: and several other Algae occurred. Although
in those various respects the biology approached the pond type,
Leptodora was rather numerous.

For far Loch. — The water was very turbid throughout, yet the fauna
was mainly lacustrine, the commonest animal being Cyclops strenuus.

L

146 BATHYMETRICAL SURVEY OF

Daphnia lacustris (large) was also common. The Cyclops was covered
with parasites of many species, both animal and vegetable.

The lochs which are drained by the Lunan burn form a connected
series, all of moderate size or very small and shallow, several being
quite stagnant and overgrown with weeds. The most important are
Lochs of the Lowes, Drumellie, and Clunie, the last being the deepest
of the whole chain. Volvox was present in most of the lochs.

Loch of Craiglush. — Most of the ordinary pelagic animals were seen.
Holopedium was abundant. Daphnia was tinged with pink, and some
males were seen; Diaptomus was dull brown; Bosmina was small.
Several small Algae, as Volvox, Pediastrum, Eudorina, were common,
and several Rotifers, as Sacculus viridis and a species of Synchceta.

Loch of the Lowes. — The plankton resembled that of Loch Craiglush,
but differed in a few points. Holopedium was more numerous, Daphnia
larger and not pink, Bythotrephes was seen, and there were fewer Algae
and Rotifers.

Loch of Butterstone. — Life was abundant, and the species were
almost all the same as in Loch Craiglush. There was less difference
between those two lochs than between Loch Craiglush and Loch of the
Lowes, which are connected by a broad canal. The Daphnia was
pink-tinged as in Loch Craiglush, and there were some males. Another
form of Daphnia also occurred, larger, and with a purple spot on each
valve.

Lochs Drumellie and Clunie. — These two lochs may be treated
together, as they are connected by a short burn and differ little in the
character of the plankton. The Daphnia in both had the parrot-shaped
head which results from the elimination of the depression in the fore-
head. Bosmina was not noted in either. Volvox was more plentiful in
Loch Drumellie, and Leptodora was common in it and not seen in
Loch Clunie.

Rae Loch (or Ardblair Loch). — The most common animal was
Notholca longispina. The Daphnia was small, the Diaptomus mostly
immature, and Bosmina was not seen. A large bizarre-shaped In-
fusorian with green body-contents was numerous.

Black Loch. — The only common organisms were Diaptomus (pale
red), Daphnia (large), Polyphemus, and some small Diatoms.

White Loch and Fingask Loch. — These two lochs, which are con-
nected by a short burn, are very similar, Daphnia (large) being much
the most abundant animal, a few bearing ephippia and some males
being seen. Diaptomus was hyaline and immature. Volvox was more
plentiful in Fingask Loch. Lejjtodura was only seen in the White
Loch.

Stormont Loch. — The water of this stagnant pond was quite turbid
and yellow in colour from the superabundance of Daphnia. The nets
could not be drawn through the water in the usual way without getting

THE FRESH- WATER LOCHS OF SCOTLAND. 147

quite choked with animals. A single dip of the net, by which about
half a gallon of water would be strained, collected enough material to
fill a 2-oz. bottle. The Daphnia was of two forms, one small and the
other much larger than usual, and 'many males were seen. There was
little else in the loch, only Diaptomus (hyaline) and a species of
Aiiabcena being at all plentiful.

Monk Myre. — Notholca longispina formed a " Wasserblut " here,
giving the collection a reddish colour. Diaptomus (grey or hyaline),
Bosmina cornuta, and Polyphemus were common.

148

BATHYMETRICAL SURVEY OF

LOCHS OF THE INVER BASIN.

SEVEN lochs which drain into Loch Inver were sounded by the Lake
Survey, viz. : Lochs Assynt, Leitir Easaich, Awe, Maol a' Choire,
Beannach, Druim Suardalain, and na Doire Daraich; the largest and

Eng. Miles

FIG. 27. INDEX MAP OF THE INVER, ROE, KIRKAIG, POLLY, AND GARVIE BASINS

most important is Loch Assynt (see Index Map, Fig. 27). There were a
few small lochs belonging to this drainage basin which were not
sounded, because there were no boats on them at the time the Lake
Survey staff visited the district.

Loch Assynt (see Plate XXXV.). — Loch Assynt lies about four miles
to the E.N.E. of Loch Inver, and the road from Lairg to Lochinver

THE FRESH- WATER LOCHS OF SCOTLAND. 149

passes along its northern shore. It receives the outflow from Lochs
Awe, Maol a' Choire, and Leitir Easaich, and its waters are discharged
by the river Inver, which, after a wild and tortuous course of over five
miles, falls into Loch Inver. It is a good fishing loch, containing trout,
sea-trout, salmon, and Salmo ferox. The ground around the western
end is low, but on proceeding eastwards it becomes higher, Beinn
Gharbh rising on the south shore to over 1700 feet, while on the north
shore Quinag attains 2600 feet, Ghlas Bheinn 2500 feet, Beinn Uidhe
2300 feet, and farther to the south-east Coniveall and Ben More Assynt
reach 3200 feet. On a promontory on the north shore about a mile
from Inchnadamph stand the ruins of Ardvreck Castle, once a strong-
hold of the M'Leods and afterwards of the Mackenzies. There are a
few small islands and islets near the shore in the western half of the
loch.

Loch Assynt has the reputation of being very wild and rough, and it
certainly fully maintained that reputation during the week spent upon
it by the staff of the Lake Survey. The general trend of the loch is
west-north-west and east-south-east, while the western end bends
sharply at Loch Assynt lodge to the south-west, and the eastern end
bends less sharply to the south-east. It is 6J miles in length, and
nearly a mile in maximum breadth, the mean breadth being half a
mile, or 8 per cent, of the length. Its waters cover an area of nearly
2000 acres, or over 3 square miles, and it drains an area fourteen times
greater, or over 43 square miles. Nearly 400 soundings were taken,
the maximum depth observed being 282 feet. The volume of water
contained in the loch is estimated at 8,730,905,000 cubic feet, and the
mean depth at 101 feet, or 36 per cent, of the maximum depth. The
length of the loch is 120 times the maximum depth and 330 times
the mean depth.

The floor of Loch Assynt is rather irregular, as shown by the
longitudinal section and two cross sections on the map; this is more
especially the case in the half lying to the north of the medial line.
The 100-feet contour running along the northern shore is of a most
sinuous character, quite independent of the shore-line, and is in striking
contrast to the same contour running along the southern shore. In the
position of the cross section E — F, moreover, the 150-feet and 200-feet
contours show a curious prolongation in a northerly direction, and
here an isolated sounding of 210 feet was recorded separated from the
200-feet area by a sounding of 198 feet. The 50-feet, 100-feet, and
150-feet basins are continuous areas, while the area over 200 feet in
depth is cut up into four portions, and that over 250 feet in depth into
three portions. The 50-feet basin extends practically from one end of
the loch to the other ; the 100-feet basin stretches from 200 yards from
the eastern end to beyond Rudh' an Alt-toir, where the loch bends
sharply to the south-west, and is 5 miles in length ; the 150-feet basin

150 BATHYMETRICAL SURVEY OF

extends from about a quarter of a mile from the east end to Rudh' an
Alt-toir, and is 4f miles in length. The four areas exceeding 200 feet
in depth, proceeding from east to west, are — (1) a large eastern basin
1J miles in length, extending from south-east of Ardvreck Castle to
north of Garbh Dhoire ; (2) a small basin lying 150 yards to the west
of the first-mentioned, based on a sounding of 210 feet; (3) a large
western basin 1| miles in length, extending from south of the eastern
islands off the north shore to north of Torr a' Chail; and (4) a small
basin less than 100 yards further west, based on a sounding of 214 feet.
The three 250-feet basins are all very narrow, one enclosed in the large
eastern 200-feet basin, |-mile in length and with a maximum depth of
264 feet, the other two enclosed in the large western 200-feet basin, the
smaller having a maximum depth of 270 feet, the larger being nearly a
mile in length and including the maximum depth of the loch (282 feet),
which occurs to the north of Eilean Assynt. It will be observed that
the deep channel does not coincide with the central axis of the loch, but
lies for the greater part of its course much nearer the southern than the
northern shore ; opposite Ardvreck Castle, however, it crosses over and
lies nearer the northern shore in the eastern end of the loch. The
numerous large bays along both shores were found to be fairly deep.

The areas of the lake-floor at different depths, and the percentages
to the total area of the loch, are as follows : —

0 to 50 feet, 572 acres 29 per cent.

50 ,, 100 „ 559 „ 28

100,, 150 „ 351 „ 18

150,, 200 „ 270 „ 14 „

200,, 250 „ 184 „ 9

Over 250 , 46 , 2

1982 , 100

More than half the entire lake-floor is covered by less than 100 feet
of water, and the areas on both sides of the 50-feet contour-line are
nearly equal, indicating a moderate and uniform average slope down
to the depth of 100 feet, beyond which depth the slope becomes much
steeper.

Loch Assynt was surveyed on September 12 to 18, 1902. On the
12th the elevation of the lake-surface above the sea was determined,
by levelling from bench-mark, as being 215*1 feet; subsequently heavy
rains set in, so that on the 16th the water had risen to the extent of a
foot, and on the 18th to the extent of 16 inches, above the level on the
12th, and the later soundings were corrected in order to bring them
into agreement with the earlier ones. When levelled by the officers of
the Ordnance Survey on September 9, 1871, the surface of the water

THE FRESH-WATER LOCHS OF SCOTLAND. 151

was found to be 214-8 feet above sea-level. The highest drift-mark
observed was 4J feet above the level of the loch on September 12, 1902.
Temperature Observations. — Temperature observations taken in
Loch Assynt showed very little variation in the temperature of the
surface water during the week occupied by the survey, the highest
reading recorded being 55°'0 F. at 10 a.m. on September 12, towards
the east end of the loch, and the lowest 53°-6 at 10 a.m. on the 16th,
also near the east end. Beneath the surface the fall of temperature
was also small, as shown by the following serial observations taken at
noon on September 16, to the north of Garbh Dhoire : —

Surface 53° "7 Fahr.

50 feet ... 53°-5 „

150 „ .. 52°-7 „

240 „ 52°-0 „

The range of temperature from surface to bottom was thus only 10>7,
and the extreme range observed throughout the whole body of water
was only 3°'0.

Loch Leitir Easaich (see Plate XXXV.). — Loch Leitir Easaich (or
Letteressie) lies immediately to the west of, and at a slightly higher
level than, Loch Assynt, into which it flows by a stream only a few
yards in length. The ground around it is low. The waterfall at its
western end, from which the loch derives its name, is very fine. Loch
Leitir Easaich is considerably over half a mile (or about 1100 yards) in
length, the maximum breadth being two-fifths of a mile (or about 700
yards), and the mean breadth about one-eighth of a mile (or about 230
yards), or 21 per cent, of the length. Its waters cover an area of about
62 acres, and it drains an area thirty-three times greater, or 2| square
miles. Nearly 30 soundings were taken, the maximum depth observed
being 70 feet. The volume of water is estimated at 44,909,000 cubic
feet, and the mean depth at 20 feet, or 28 J per cent, of the maximum
depth. The loch is extremely irregular in outline, the main body
trending north and south, with an arm running in an easterly direction
towards Loch Assynt. The maximum depth observed in this arm was
31 feet, separated by shallower water from the deep basin in the main
body of the loch, where there is a small area exceeding 50 feet in depth
towards the western shore. The areas between the contour-lines, and
the percentages to the total area of the loch, are as follows : —

0 to 25 feet 36 acres 68 '8 per cent.

25 „ 50 „ 22 „ 23-6

Over 50 , 4 7'6

62 , 100-0

152 BATHYMETRICAL SURVEY OF

Over two-thirds of the entire area of the loch is thus covered by less than
25 feet of water. Loch Leitir Easaich was surveyed on September 18,
1902, the elevation of the water surface being 217 feet above the level
of the sea, and half a foot higher than the water in Loch Assynt on the
same date. After very heavy rains the two lochs must stand at the same
level. The boatmen stated that the water in Loch Leitir Easaich would
rise very little higher than on the date surveyed, and would fall about
two feet lower than this level.

Loch Maol a' Choire (see Plate XXXVI.).— Loch Maol a' Choire
(or Mulach-Corrie, or the Gillaroo Loch) is situated about two miles to
the south-west of Inchnadamph, and flows by the Allt na Glaice Motre
into the river Traligill, which falls into the head of Loch Assynt near
the entrance of the river Loanan. The loch derives one of its names
from the supposed resemblance of its fish to the Gillaroo trout of Lough
Melvin; in shape the trout are very deep and thick, and hence very
heavy in proportion to their length. Loch Maol a' Choire trends in a
north and south direction, and is about 600 yards in length by about
250 yards in maximum breadth. It covers an area of about 20 acres,
and drains an area of about 512 acres — an area twenty-five times greater
than that of the loch. Forty soundings were taken, the maximum depth
observed being 8 feet. The volume of water is estimated at 4,452,000
cubic feet, and the mean depth at 5 feet. The loch is fairly uniform
in depth, deepening gradually on proceeding from the southern end
towards the north-western shore, off which two soundings of 8 feet were
taken. It was surveyed on September 13, 1902 ; its elevation above the
sea was not determined by levelling, but is between 800 and 900 feet,
the ground surrounding it being covered by peat. The temperature of
the water was uniform at 49°-2 on the date of the survey.

Loch Awe (see Plate XXXVI.). — Loch Awe is situated nearly four
miles to the south of Inchnadamph, by the side of the road leading to
Alltnacealgach. The ground to the south-east is peat-covered, while
Canisp rises on the south-west, Cnoc an Leathaid Bhuidhe on the west,
and Beinn an Fhuarain on the east. Its principal feeder, the burn flow-
ing from Loch na Cruagaich, enters the loch at its northern end, within
30 yards of the mouth of the river Loanan, which carries the outflow
into Loch Assynt. The fishing has been much improved of late years, and
it is now a good salmon loch, the fish running through Loch Assynt into
it. Loch Awe trends north and south, and is over four-fifths of a mile
(or about 1400 yards) in length, with a maximum breadth of less than
one-third of a mile (or about 530 yards), the mean breadth being about
one-half of tbis. It covers an area of about 86 acres, and drains an area
twenty-four times greater, or 31 square miles. Over 60 soundings were

THE FRK>H-\VATKK LOCHS OF SCOTLAND. 153

taken, the maximum depth observed being 7 feet. The volume of water
is estimated at 17,751,000 cubic feet, and the mean depth at nearly
5 feet. Loch Awe is thus very shallow, a large part being overgrown
by weeds and rushes; the maximum depth of 7 feet was observed in
two places in the northern portion of the loch. It was surveyed on
September 23, 1902. The elevation above the sea was determined, by
levelling from bench-mark, as being 504 feet. This is almost identical
with the level observed by the officers of the Ordnance Survey on
September 6, 1871, viz., 504-1 feet. The temperature of the water was
found to be uniform at 53°'5.

Loch Beunnach (see Plate XXXVI.). — Loch Beannach lies about
two miles to the west of Loch Assynt and four miles from Lochinver.
It flows into Loch Bad nan Aighean (which was not sounded), thence
by a short stream into the river Inver after leaving Loch Assynt. It
is most irregular in outline and in conformation, with numerous islands,
the majority of which are thickly wooded and give to the loch a beautiful
appearance. Loch Beannach is 1J miles in length, with a maximum
breadth of less than one- third of a mile (or about 530 yards), the mean
breadth being about one-seventh of a mile (or about 250 yards). Its
waters cover an area of about 117 acres, and it drains an area ten
times greater, or nearly two square miles. Over 60 soundings were
taken, the maximum depth observed being 38 feet. The volume of
water is estimated at 67,348,000 cubic feet, and the mean depth at 13
feet. As already indicated, the floor of the loch is very uneven. It falls
in four places below the 20-feet level, the deepest part of the loch being
in the south-western portion, where three soundings exceeding 30 feet
were taken, the maximum depth of 38 feet having been observed about
100 feet to the north of the small island lying off the southern shore,
indicating in this position a slope of 1 in 2'6. The area of the lake-floor
covered by less than 25 feet of water is about 105 acres, or 89 per cent,
of the total area of the loch. Loch Beannach was surveyed on Septem-
ber 19, 1902. Its elevation above the sea could not be determined, but
must be between 230 and 280 feet. The highest drift-mark observed
was 3 feet above the level of the water on the date of the survey, and
the boatman stated that the water might fall about 2 feet lower ; thus
a range in the level is indicated of about 5 feet. The temperature of the
surface water was 52°-5, and at a depth of 30 feet 52°-0. The range
of temperature throughout the body of water was thus very small.

Loch Druim Suardalain (see Plate XXXVI.). — Loch Druim
Suardalain lies about a mile to the east of Loch Inver and half a mile
to the east of Loch na Doire Daraich, into which it flows by the Uidh
a' Bhalgain. Its principal feeder is the Amhainn Bad na h-Achlaise,

154 BATHYMETRICAL SURVEY OF

bearing the outflow from Loch na Gainimh in the Canisp forest. The
ground around the loch is low. It is three-quarters of a mile in length,
and a quarter of a mile in maximum breadth, the mean breadth being
one-sixth of a mile. Its waters cover an area of about 79 acres, and it
drains an area 105 times greater — an area of nearly 13 square miles.
Seventy-five soundings were taken, the maximum depth observed being
31 feet. The volume of water is estimated at 35,408,000 cubic feet, and
the mean depth at over 10 feet. Loch Druim Suardalain is irregular in
outline, with a few islands, and the conformation of the bottom is
peculiar. Towards the eastern end is a small area exceeding 20 feet in
depth, the deepest sounding in this position being 29 feet, but the
maximum depth of the loch (31 feet) was observed quite close to
the south-western shore, apparently a deep hole surrounded by much
shallower water. The area of the lake-floor covered by less than 10
feet of water is about 45 acres, or 58 per cent, of the total area of the
loch. The loch was surveyed on September 15, 1902, and the elevation
above the sea was determined, by levelling from bench-mark, as being
134-5 feet; when levelled by the officers of the Ordnance Survey on
September 19, 1871, the elevation was found to be 133-1 feet above sea-
level. The temperature of the water was found to be uniform at 530>2.

Loch na Doire Daraich (see Plate XXXVI.). — Loch na Doire
Daraich (or Loch Culag, as it is more generally called in the district)
is situated about a quarter of a mile to the south-east of Loch Inver,
into which it flows by the Amhainn na Culeig ; its chief supply of water
is derived from Loch Druim Suardalain. The surrounding ground is
low, but is steeper to the south and south-west, and on the western side
thickly wooded. It is very irregular in outline and conformation, and
the two arms projecting southwards are to a large extent filled with
weeds. The length from south-west to north-east is half a mile, and the
maximum breadth a quarter of a mile, the mean breadth being one-
seventh of a mile. Its waters cover an area of about 44 acres, and it
drains directly an area exceeding a square mile, but since it receives the
outflow from Loch Druim Suardalain, its total drainage area is about
14 square miles, an area 203 times greater than that of the loch. Over
40 soundings were taken, the maximum depth observed being 9 feet.
The volume of water is estimated at 6,922,000 cubic feet, and the mean
depth at 3 J feet. The loch is very shallow, but it is curious to note that
the deeper soundings were taken near shore ; soundings of 5 and 6 feet
were recorded in four places close to the shore, an isolated sounding of
7 feet was taken at the entrance of the inflowing burn from Loch Druim
Suardalain, while the maximum depth of the loch was observed close to
the large promontory on the western shore. Loch na Doire Daraich
was surveyed on September 20, 1902, the elevation of the lake-surface
being 72*5 feet above the sea; when levelled by the officers of the

THE FRESH- WATER LOCHS OF SCOTLAND. 155

Ordnance Survey on August 26, 1870, the elevation was found to be
73 '7 feet above sea-level. The boatman stated that the water may rise
2 feet above its level on September 20, 1902, and fall 3 feet lower,
giving a range of 5 feet. Temperature observations gave 50°'5 at the
surface, and 50°'l at a depth of 7 feet.

156 BATHYMETRICAL SURVEY OF

LOCHS OF THE ROE BASIN.

THE two principal lochs only in this basin, Lochs Crocach and an Tuirc,
were surveyed; the smaller ones could not be sounded from lack of
boats.

Loch Orocach (see Plate XXXVII.). — Loch Crocach lies about three
miles to the north of Loch Inver, and about a mile to the north-west of
Loch an Tuirc, into which its waters are discharged. It is most
irregular in outline and in conformation, and is studded with islands
large and small; indeed the insulosity (i.e., the ratio between the area
of the islands and the total area of the loch) is one of its distinguishing
characteristics, being probably higher than in any other loch visited by
the Lake Survey, the lochs most nearly approaching it in this respect
being Lochs Maree and Lomond. The islands are mostly congregated
in the large western bay; they are low, heather-covered, and not
wooded as in the majority of the lochs in the district. The ground
around the loch is low; from 350 to 700 feet above the sea. Loch
Crocach trends north-east and south-west, and is nearly 1| miles in
length and over one-third of a mile (or about 700 yards) in maximum
breadth, the mean breadth being about one-sixth of a mile (or rather
less than half the maximum breadth). Its waters cover an area of
about 160 acres (or one-quarter of a square mile), exclusive of the
numerous islands, and it drains an area seven times greater, or If square
miles. Nearly 80 soundings were taken, the maximum depth observed
being 71 feet. The volume of water is estimated at 147,987,000 cubic
feet, and the mean depth at nearly 17 feet. Loch Crocach is deeper
than the other small lochs in this district. A large 2 5 -feet area occupies
the greater portion of the length of the loch to the north-west of the
islands ; a second smaller area occurs in the south-western expansion of
the loch, and a third very small area lies near the south-western end
of the loch, based on a sounding of 30 feet. The bottom falls in two
places below the 50-feet level, the larger basin being centrally placed,
between the entrance of the Uidh nan Lion and the largest of the
islands, with a maximum depth of 64 feet, the smaller but deeper basin
lying in the south-western expansion of the loch, the maximum depth
of 71 feet having been observed quite close to the small island off the

THE FRESH- WATER LOCHS OF SCOTLAND. 157

southern shore. The areas between the consecutive contour-lines, and
the percentages to the total area of the loch, are as follows : —

0 to 25 feet 109 acres 68 '3 per cent.

25 „ 50 „ 45 „ 28-0

Over 50 , 6 . 3'7

160 , 100-0

Loch Crocach was surveyed on September 17, 1902, but the elevation
of the lake-surface above the sea could not be determined ; the elevation
must be between 350 and 370 feet above sea-level. The boatman stated
that the water might rise 2 feet above, and fall 3 feet below, the level
on the date of the survey.

Temperature Observations. — Temperature observations showed a
greater variation than was observed in the larger and deeper Loch
Assynt, as will be seen from the following serial taken at 2.30 p.m. on
September 17, 1902: —

Surface 53°7 Fahr

40 feet 53° 2 „

70 ;, 50°-8 ,,

This series shows a range of 3°, the greatest fall of temperature
occurring in deep water below 40 feet.

Loch an Tuirc (see Plate XXXVII.). — Loch an Tuirc is situated
about two miles north-east of Loch Inver, and over a mile to the west
of Loch Beannach. It receives the outflow from Loch Crocach, and
flows by the Uidh nan Caorach into Loch an Aite Mhoir, thence
through three other small lochs into Loch Roe. The ground around the
loch is low, the greatest elevation being one of 400 feet to the north-west
of the loch. Islands are not so numerous in this loch as in the neigh-
bouring Lochs Beannach and Crocach; weeds are very abundant in
some parts of the loch. Loch an Tuirc trends north-east and south-
west, and is irregular in outline and conformation. There is a con-
striction near the centre of the loch, which cuts the deeper water into
two portions, and the loch narrows gradually towards the outflow at the
south-west end. It is about four-fifths of a mile (or about 1400 yards)
in length, with a maximum breadth of one-fifth of a mile (or over 300
yards), the mean breadth being one-tenth of a mile. Its waters cover
an area of about 53 acres, and it drains directly an area of about 1J
square miles, but, since it receives the outflow from Loch Crocach, its
total drainage area is nearly 3 square miles. Nearly 100 soundings
were taken, the maximum depth observed being 39 feet. The volume of
water is estimated at about 24,787,000 cubic feet, and the mean depth
at 10 \ feet. The portion of the loch to the north-east of the central

158 BATHYMETRICAL SURVEY OF

constriction is shallow and obstructed by weeds ; a small area exceeding
10 feet in depth runs along the southern shore, the maximum depth
therein being 13 feet. The wide portion of the loch to the south-west of
the constriction forms a regular deep basin, the maximum depth of 39
feet being found in the north-eastern part of the basin. The areas at
different depths, and the percentages to the total area of the loch, are
as follows : —

0 to 10 feet 35 acres 65 '8 per cent.

10 „ 25 „ 12 „ 23-2

Over 25 , 6 , 11 -0

53 , 100-0

Loch an Tuirc was surveyed on September 17, 1902, but the elevation
of the lake-surface above the sea could not be determined ; the elevation
is apparently slightly under 200 feet. Temperature observations at
3 p.m. gave identical readings of 53°'0 at the surface and at depths of
20 and 30 feet.

THE FRESH-WATER LOCHS OF SCOTLAND.

159

LOCHS OF THE KIRKAIG BASIN.

THE lochs belonging to this basin form a connected series : — Loch
Borralan flows by the Ledmore river into the Ledbeg river, which
farther on joins the Na Luirgean, bearing the outflow from Loch

FIG. 28. LOCH BORRALAN, FROM THE HOTEL ; CUL MOR IN THE DISTANCE.

(Photograph by H. Anderson.)

Urigill, and together they flow into the Cam Loch, which empties itself
into Loch Veyatie, thence into Loch Fionu, and thence by the Kirkaig
river into Loch Kirkaig. Lochs Veyatie, Fionn, and Borralan lie
partly in Ross-shire and partly in Sutherlandshire, the boundary
running down the centre of the two first-named lochs, and across the
south-eastern end of Loch Borralan. All the lochs are good trout lochs,
and Loch Veyatie contains also Salmo feroz, while char are numerous
in Loch Borralan.

160 BATHYMETRICAL SURVEY OF

Loch Borralan (see Plate XXXVI.). — Loch Borralan (or Borrolan
or Boarlan) trends north-west and south-east, and the road from Lairg
to Inchnadamph runs along its north-eastern shore; Aultnacallagach
Inn is situated on the road close to the loch near its south-eastern end.
The ground around the loch is low except to the north, where Cnoc na
Sroine rises to 1300 feet; to the south-west the ground is thickly
covered with peat. The abundance of char in the loch is remarkable
considering its shallowness. Weeds were seen growing on the bottom
almost everywhere, and over large areas they reach to the surface. It is
over a mile in length, with a maximum breadth of nearly a quarter of a
mile (or about 400 yards), the mean breadth being about one-sixth of a
mile (or over 300 yards). Its waters cover an area of about 118 acres,
and it drains an area 34 times greater, or 6J square miles. Over 60
soundings were taken, the maximum depth observed being 21 feet.
The volume of water is estimated at 49,324,000 cubic feet, and the mean
depth at 9J feet. The maximum depth of 21 feet was observed towards
the south-eastern end, opposite the entrance of the Allt nan Cealgach ;
in the north-western portion of the loch a maximum depth of 16 feet
was found, the 10-feet contour-line being continuous almost from end to
end of the loch. Loch Borralan was surveyed on September 1, 1902.
The elevation of the lake-surface above the sea was determined, by
levelling from bench-mark, as being 459-7 feet, which is almost identical
with that observed by the Ordnance Survey officers on August 31, 1871,
viz., 459-8 feet. According to the boatman, the water in the loch might
fall about 4 inches lower than on the date of the survey, and in
exceptional floods might rise 5 feet higher. Temperature cbservations
at 3 p.m. gave identical readings of 56°-7 at the surface and at a depth
of 16 feet.

Loch Urigill (see Plate XXXVI.).— Loch Urigill (or Urigall) lies
less than a mile to the south-west of Loch Borralan. The ground
around the loch is low and covered with peat. Like Loch Borralan,
it trends in a north-west and south-east direction; in fact, nearly all
the lochs in this district generally trend north-west and south-east, as
will be seen from the small index map (Fig. 27). It is nearly two miles
in length, with a maximum breadth of nearly three-quarters of a mile,
the mean breadth being nearly half a mile. Its waters cover an area
of about 500 acres (or over three-quarters of a square mile), and it drains
an area 14 times greater, or 11 square miles. Nearly 130 soundings
were taken, the maximum depth observed being 40 feet. The volume of
water is estimated at 285,088,000 cubic feet, and the mean depth at
13 feet. Loch Urigill is, on the whole, very shallow, nearly 99 per cent,
of the lake-floor being covered by less than 25 feet of water, and weeds
are abundant in some places. The 10-feet area is continuous from close
to the north-west end to near the south-east end, opposite the entrance

THE FRESH-WATER LOCHS OF SCOTLAND.

161

of the Allt nam Meur. Midway along the loch, towards the north-
eastern shore, is a rise of the bottom covered by only 3 feet of water.
The deepest part of the loch is near the north-west end, where there is
a small central area exceeding 20 feet in depth, the maximum depth
being 40 feet ; this little depression is well denned by a steep gradient.
Loch Urigill was surveyed on August 30, 1902. The level of the loch
could not be determined ; when visited by the officers of the Ordnance
Survey on October 5, 1871, the elevation was found to be 514-7 feet
above the sea.

f- -W:^*^

FIG. 29. LOCH TJRIGILL, WITH SUILVEN AND CANISP IN THE DISTANCE.

(Photograph by Mr. H. Anderson.)

Temperature Observations. — Temperature observations taken at
4 p.m. on August 30, 1902, gave the following results: —

Surface
10 feet
20 .,
3o .

57° -2 Fahr.
56°-0 ,,
56°-0 „

55° -8

Cam Loch (see Plate XXXVIII.).— Cam Loch (or Loch Cama) lies
about a mile to the north-west of Loch Urigill, and a mile to the west
of Ledmore. It is extremely irregular in outline and in conformation,
and includes one large and several small islands. The principal feeder
is the stream bearing the outflow from Lochs Borralan and Urigill,
which enters the loch at its south-eastern end, and here also is the exit
of the loch, the Amhuinn Mhor after a course of a few hundred yards

162

BATHYMETRICAL SURVEY OF

falling in a magnificent cascade into Loch Veyatie. The ground in the
immediate vicinity of the loch is low, but to the east lies Cnoc na Sroine,
and to the north-east Cnoc na Leathaid Bhuidhe, while to the west-
north-west Suilven, and to the north Canisp, form remarkably fine
objects, which catch the eye from every part of the loch. The length of
the loch is 2 1 miles, the maximum breadth over three-quarters of a
mile, and the mean breadth over one-third of a mile. Its waters cover
an area of about 647 acres, or over one square mile, and it drains
directly an area of over 16 square miles, but since it receives the
outflow from Lochs Borralan and Urigill its total drainage area is about

FIG. 30. CAM LOCH, WITH SUILVEN IN THE DISTANCE.

h bi/ Rev. H. N. Jion/ir. i

33J square miles. Over 200 soundings were taken, the maximum
depth observed being 122 feet. The volume of water is estimated at
1,062,543,000 cubic feet, and the mean depth at nearly 38 feet. The
south-eastern portion of the loch is shallow, very few soundings ex-
ceeding 20 feet being recorded, the maximum observed being 40 feet a
short distance to the east of Eilean na Gaoithe. Most of the islands are
found in this part of the loch, Eilean na Gartaig being the largest, while
Eilean na Gaoithe is remarkable for the long spit of sand and shingle
which stretches from its northern point for a distance of nearly 100
yards ; this spit is submerged when the water is high, but at the time

THE FRESH- WATER LOCHS OF SCOTLAND. 163

of the survey it rose some six inches above the surface of the water.
The main basin is contained in the north-western portion of the loch,
where the bottom falls in two places below the 100-feet level, separated
by a slight shoaling of the water over a short interval. The larger of
these two 100-feet areas near the centre of the loch is three-quarters of
a mile in length, and the smaller, half a mile in length, approaches
within less than half a mile from the north-west end, running com-
paratively close to the south-eastern shore. It is curious to note that
the maximum depth observed in each of these two areas is identical (122
feet), though the two soundings are separated by an interval of about
a mile ; the deepest water on the rise between the two areas is 83 feet.
The slope along the north-eastern shore towards the north-west end of
the loch is very steep; in one place a sounding of 91 feet was taken
about 20 feet from the shore, and the cliff above was almost vertical and
50 feet in height. The areas between the consecutive contour-lines, and
the percentages to the total area of the loch, are as follows : —

0 to 25 feet 320 acres 49 '5 per cent.

25 „ 50 „ 151 ,, 23-3

50 „ 75 „ 67 „ 10-4

75 „ 100 „ 67 „ 10-4

Over 100 . 42 . 6 "4

647 , 100-0

Cam Loch was surveyed on August 27 and 28, 1902. The elevation
of the lake-surface above the sea could not be determined, but when
levelled by the Ordnance Survey officers on October 7, 1871, it was
found to be 404-8 feet above sea-level. Judging from the level of the
other lochs in the district at the end of August, 1902, its level was
probably about a foot lower than that quoted, and the boatman stated
that he had never seen the water more than two or three inches lower ;
the highest drift-mark seen was 3*7 feet above the surface of the water
on August 27, 1902. The temperature of the surface water was 56°'2.

Loch Veyatie (see Plate XXXVIII.).— Loch Veyatie lies about half
a mile to the west of the village of Elphin. It receives the water from
the Cam Loch at its south-eastern end, where also the Amhainn a'
Chnocain enters the loch ; the water is discharged at the north-western
end of the loch by the Uidh Fhearna into the Fionn Loch. The ground
around the loch is low, except where Cul Mor rises to a height of over
2700 feet to the south-west, and Suilven (already referred to) to
the north-west. The loch is over 4 miles in length, with a maximum
breadth of nearly half a mile, the mean breadth being nearly a quarter
of a mile (or about 400 yards). Its waters cover an area of about 593
acres (or nearly one square mile), and it drains directly an area of over

164 BATHYMETRICAL SURVEY OF

11 J square miles, but since it receives the outflow from the Cam Loch
and from Loch a' Mhiotailt, its total drainage area is about 46J square
miles— an area 50 times greater than that of the loch. Over 200
soundings were taken, the maximum depth observed being 126 feet.
The volume of water is estimated at 1,061,544,000 cubic feet (almost
identical with the volume of the Cam Loch), and the mean depth at
41 feet. The floor of Loch Veyatie is uneven, as is well shown in the
sections on the map, with a few islands here and there along the shores,
and some of the bays are filled with weeds. A continuous area exceeding
25 feet in depth extends nearly from one end of the loch to the other,

FIG. 31. LOCH VEYATIE, WITH SUILVEN IN THE DISTANCE.

(Photograph by Rev. H. N. Bonar.)

with an isolated sounding of 26 feet close to the south-eastern end off
the promontory between the two inflowing streams, and with a small
separate area having a maximum depth of 53 feet at the north-western
end. Within the large 25 -feet area the bottom undulates in such a
manner as to form two 50-feet areas and three 100-feet areas. Of the
two 50-feet areas, the smaller but deeper one lies off the entrance to
Loch a' Mhiotailt, and is three-quarters of a mile in length : it encloses
the main 100-feet basin and the maximum depth of the loch (126 feet),
winch was observed about 220 yards from the northern shore. The
larger 50-feet area lies in the south-eastern portion of the loch, and is

THE FRESH- WATER LOCHS OF SCOTLAND. 165

two miles in length ; it encloses two small 100-feet basins with maximum
depths of 113 and 103 feet respectively, separated by a rise of the bottom
on which the depth is 82 feet. The areas between the consecutive
contour-lines, and the percentages to the total area of the loch, are
as follows : —

Oto 25 feet 230 acres 38 '8 per cent.

25 „ 50 ,, 215 „ 36-2

50,, 75 „ 94 „ 15-9

75 „ 100 „ 38 „ 6-4

Over 100 , 16 . 2'7

593 . 100-0

Thus 75 per cent, of the lake-floor is covered by less than 50 feet of
water. Loch Veyatie was surveyed on August 29 and September 8,
1902. On commencing the survey 011 August 29, the elevation of the
lake-surface was determined, by levelling from bench-mark, as being
364-8 feet above the sea ; in the interval between the two days devoted
to the survey the water rose to the extent of 15 inches, then gradually
fell again, and on September 8 the elevation was found to be 365-6 feet
above the sea. The soundings taken on the last-mentioned date have
been corrected accordingly, in order to bring them into agreement with
those taken on the earlier date. The boatman stated that the water in
the loch was about its lowest level on August 29, 1902, and the highest
drift-mark seen was 3 feet above the surface of the water on that date.
The officers of the Ordnance Survey found the level of Loch Veyatie
to be 365-7 feet above the sea on September 8, 1870. Temperature
observations taken at 3.30 p.m. on September 8, 1902, indicated an
almost uniform temperature throughout the waters of the loch, the
readings at the surface and at a depth of 50 feet being identical (55°'9),
and at a depth of 100 feet 55°-8.

Loch a' Mhiotailt (see Plate XXXVIII.).— Loch a' Mhiotailt
(pronounced Vattle) lies immediately to the south-west of Loch Veyatie ;
in fact, they may almost be looked upon as one loch, for after heavy
rains there is a channel about 20 feet in length, 10 feet in breadth, and
1 foot in depth connecting the lochs. When the water is low, however,
the separation is complete, the barrier being formed by one of the basic
dykes so numerous in this part of the gneiss : the rock is in places
covered by a thin layer of sand. The ground around the loch rises
steeply up to a height of 100 to 200 feet above the surface of the water,
so that the loch is almost shut in, and only towards Loch Veyatie can
any opening in the wall of rock be seen. Loch a' Mhiotailt is over
half a mile in length from east to west, the maximum breadth exceeding
a quarter of a mile, the mean breadth being about one-seventh of a mile,

166 BATHYMETRICAL SURVEY OF

or about 300 yards. Its waters cover an area of about 52 acres, and it
drains an area of 1J square miles. Thirty soundings were taken, the
maximum depth observed being 69 feet. The volume of water is
estimated at 69,264,000 cubic feet, and the mean depth at 30 feet.
The loch is irregular in outline, what may be called the body of the
loch sending out a broad arm at right angles. The 25-feet area follows
approximately the outline of the loch, and encloses two 50-feet basins,
one towards the extremity of the arm containing the maximum depth
of the loch (69 feet), the other centrally placed in the body of the loch
with a maximum depth of 65 feet. The greatest depth observed between
the two 50-feet basins was 38 feet. The areas between the consecutive
contour-lines and the percentages to the total area of the loch are as
follows : —

0 to 25 feet 21 acres 40 '2 per cent.

25 „ 50 „ 22 „ 42-7

Over 50 , 9 „ 17'1

52 , -100-0

Loch a' Mhiotailt was surveyed on September 8, 1902, when the
water was at the same level as that in Loch Veyatie, viz., 365*6 feet
above the sea. The soundings have been corrected in the same manner
as the soundings taken in Loch Veyatie on the same date, so as to bring
all the soundings into agreement with those taken in Loch Veyatie on
August 29, 1902, when the surface of that loch stood at a level of 364-8
feet above the sea.

Fionn Loch (see Plate XXXVIII.).— Fioiin Loch (or Loch Fewin
or Fewn) lies about three miles to the east of Enard Bay and three-
quarters of a mile to the north-west of Loch Veyatie, from which it
derives the greater part of its water. Besides this, however, it drains
the southern slopes of Suilven, which is little more than a mile distant
from the loch. The great feature of the Fionn Loch is the existence of
alluvial terraces surrounding the loch. The two lowest are the most
extensive, together having an average breadth of 100 yards, their
heights being about 20 and 30 feet above the surface of the loch. When
the water stood at this level Loch Fionn must have been connected with
Loch Veyatie, the difference in their levels, as observed by the Lake
Survey, being only about 8 feet. This former loch must have formed
a fine sheet of water some 7 \ miles in length, with a winding arm where
is now Loch a' Mhiotailt. There is another still higher terrace seen to
the north of Na Tri Lochaii. The Fionn Loch discharges its waters by
the Kirkaig river, which forms the renowned Falls of Kirkaig about
three-quarters of a mile below the loch. Very heavy rains fell on the date
of the survey and on the previous days, and in the narrow parts of the

THE FRESH- WATER LOCHS OF SCOTLAND. 167

loch, especially in the one to the south of Creag a' Choire Mhoir, the
current was so strong that the greatest difficulty was experienced in
rowing the boat against it, though assisted by a strong north-west wind.
The loch is nearly 2J miles in length, with a maximum breadth of oyer
one-third of a mile (or about 600 yards), the mean breadth being about
one-seventh of a mile (or about 250 yards). Its waters cover an area
of about 209 acres (or nearly one-third of a square mile), and it drains
directly an area of about 6J square miles, but since it receives the
outflow from Loch Veyatie and the other lochs in the basin, its total
drainage area is nearly 53 square miles — an area 160 times greater
than that of the loch. Over 100 soundings were taken, the maximum
depth observed being 90 feet. The volume of water is estimated at
185,510,000 cubic feet, and the mean depth at 20J feet. Fionn Loch
is very irregular in outline, broads and narrows alternating with each
other, and the contours of the bottom are correspondingly diversified.
There is a long narrow tortuous area exceeding 25 feet in depth,
extending from near the north-west end of the loch to north of the
reedy bay where the stream from Na Tri Lochan enters, and about
H miles in length; a short distance to the south-east is a second small
25-feet area, with a maximum depth of 37 feet. The deepest water
occurs in the wide part of the loch about half a mile to the south-east
of the exit of the Kirkaig river, where there is a small area exceeding
75 feet in depth, the maximum depth of 90 feet having been observed
about 120 yards from the south-western shore. The areas between
the consecutive contour-lines, and the percentages to the total area of
the loch, are as follows : —

0 to 25 feet 153 acres 73 '0 per cent.

25 „ 50 „ 49 „ 23-5
50,, 75 „ 2 ,, 1-0

Over 75 . 5 . 2*5

209 ., 100-0

This table shows how circumscribed the deep-water area is, 97 per cent,
of the lake-floor being covered by less than 50 feet of water. The Fionii
Loch was surveyed on September 16, 1902. The elevation of the lake-
surface was determined, by levelling from bench-mark, as being 356-9
feet above the sea ; when levelled by the officers of the Ordnance Survey
on October 21, 1870, the elevation was found to be 357*1 feet above
sea-level. The temperature of the surface water on September 16, 1902,
was 53°-0.

168 BATHYMETRICAL SURVEY OF

LOCHS OF THE POLLY BASIN.

ONLY the two principal lochs in this basin (Lochan Gainmheich and
Loch Skinaskink) were surveyed; Loch na Doire Seirbhe, Loch Lon
na-h-TJamha, Loch Uidh Tarruingeach, and other smaller lochs had no
boats on them at the time of the visit of the Lake Survey, and it was
found impracticable to have boats transported to them. The waters of
Lochan Gainmheich are discharged into Loch Skinaskink, thence by
the river Polly into Loch Polly, an inlet of Enard Bay.

Lochan Gainmheich (see Plate XXXIX.). — Lochan Gainmheich lies
about 1£ miles to the north of Loch Lurgain and a quarter of a mile to
the south-west of Loch Skinaskink, into which its waters are discharged
by the Allt Lochan Gainmheich. The eastern end of the loch lies
between Cul Mor and Cul Beag, and to the west An Stac rises to over
2000 feet; Cul Beag and An Stac are connected by a ridge between
Loch Lurgain and Lochan Gainmheich over 200 feet above the level of
the loch, so that only towards Loch Skinaskink can an extensive view
be obtained. The southern shore of Lochan Gainmheich is thickly
wooded, but the northern and western shores are bare. The loch is
naturally divided into a larger and deeper southern portion and a
smaller and shallower northern portion, and it has been found con-
venient to measure these two distinct portions separately.

The southern portion is a mile in length from east to west, and
nearly half a mile in maximum breadth, the mean breadth being over
one-fifth of a mile. The area is about 135 acres, and it drains an area
of nearly 2f square miles. Over 50 soundings were taken, and the
maximum depth observed was 120 feet. The volume of water is
estimated at 245,711,000 cubic feet, and the mean depth at nearly 42
feet. This portion of Lochan Gainmheich is extremely simple in
conformation, the bottom sinking down on all sides towards the deepest
part, which is approximately centrally placed. The 50-feet area is
about 1100 yards in length, and the 100-feet area about 400 yards in
length, the maximum depth of 120 feet having been observed about
130 yards from the southern shore. The areas between the contour-
lines, and the percentages to the total area, are as follows : —

THE FRESH- WATER LOCHS OF SCOTLAND. 169

0 to 50 feet 76 acres 56 -5 per cent.

50,, 100 „ 45 „ 33-4 „

Over 100 , 14 . lO'l

135 „ 100-0

The northern portion is one-third of a mile in length, with a
maximum breadth of a quarter of a mile and a mean breadth of one-
sixth of a mile. The area is about 40 acres, and it drains directly an
area of about 5 square miles, but, including the area draining into the
southern portion, the total drainage area is about 7| square miles.
Over 20 soundings were taken, the maximum depth observed being 59
feet. The volume of water is estimated at 43,274,000 cubic feet, and
the mean depth at 24 J feet. The floor of this portion of Lochan
Gainmheich is not so perfectly regular in conformation as that of the
southern portion. There is an isolated sounding of 27 feet opposite the
outflow, and within the 25 -feet area the bottom is slightly undulating ;
the maximum depth of 59 feet was observed about 120 yards from the
southern shore, and this was the only sounding exceeding 45 feet in
depth.

Lochan Gainmheich was surveyed on September 10, 1902, the
surface of the water being 251*5 feet above sea-level; when levelled by
the Ordnance Survey officers on August 26, 1870, the elevation of the
lake-surface was 251'1 feet above the sea. The highest drift-mark seen
was 3-4 feet above the surface of the water on September 10, 1902.

Temperature Observations. — Temperature observations taken in the
deepest part of the loch at 4 p.m. on September 10, 1902, gave the
following results : —

Surface 55°'5 Fahr.

50 feet 55°-3 „

110 „ 54°-0 „

Loch Skinaskink (see Plate XXXIX.). — Loch Skinaskink (or
Shianas-kaig) is a large loch lying about 2J miles to the east of Enard
Bay, into which it drains by the river Polly. It is one of the most
interesting lochs visited by the Lake Survey, because of the extreme
irregularity both of its outline and of the conformation of the lake-floor.
So irregular is the outline of the loch that it has over 17 miles of
shore-line. It is a splendid trout loch, but preserved, and the islands
are covered with birch woods where deer are often found ; the largest
island is Eilean Mor, near the centre of the loch, and there are two
islands named Eilean Dubh, one near Eilean Mor in the centre of the
loch, and the other in the north-eastern arm. The ground to the west
and north of the loch is low, but to the east and south rise Cul Mor
(2700 feet), Cul Beag (2500 feet), and An Stac (2000 feet). There is a

170 BATHYMETRICAL SURVEY OF

sluice at the lower eud of Loch Uidh Tarruingeach (through which the
discharge from Loch Skinaskink passes into the river Polly) to control
the outflow of the water, and by its means the average level of the
loch has been raised about 3 feet. The length of Loch Skinaskink,
measured from the south-eastern end near Lochan Gainmheich to the
north-western arm near Loch na Moine Moire, is over 3 miles, and the
maximum breadth is over a mile, the mean breadth being two-thirds
of a mile. Its waters cover an area of over 2 square miles, and it
drains directly an area of nearly 8 square miles, but since it receives
the outflow from Lochan Gainmheich its total drainage area is over
15J square miles — an area only 7J times greater than the area of the
loch. Nearly 400 soundings were taken, the maximum depth observed
being 216 feet. The volume of water is estimated at 3,518,305,000
cubic feet, and the mean depth at 60^ feet. Reference has been made
to the irregularity of the floor of Loch Skinaskink, and the contour-lines
on the map have a fanciful resemblance to an intricate maze. There
are three main basins, which may be briefly described, viz. — (1) one
embracing nearly the whole of the main body and surrounding Eilean
Mor; (2) one lying in the north-eastern arm of the loch; and (3) one
lying in the north-western arm of the loch.

(1) The first basin is the largest and deepest. In it the 25-feet and
50-feet contour-lines follow approximately the outline of the shore,
running into all the large bays (except that the 50-feet line does not
enter the bay south of Camas nam Fiadh). The 100-feet area has a
very sinuous outline, almost surrounding Eilean Mor, and sending a
large tongue into the western arm of the loch. There are two areas
exceeding 150 feet in depth — one to the south of Eilean Mor enclosing
the deepest part of the loch, the other to the west and north-west of
that island extending to the north of Eilean Dubh. The 200-feet area
is small, based on soundings of 204 and 216 feet, the last-mentioned —
the deepest sounding in the loch — lying about 350 yards to the south of
Eilean Mor. The great feature of this basin is the occurrence of two
hills to the west of Eilean Mor ; the one nearest the island is covered by
38 feet of water, the depth between it and the island being 70 feet,
and between it and the south-western shore exceeding 100 feet; the
other is covered by 41 feet of water, the depth around it being from
100 to 150 feet.

(2) The second basin in the north-eastern arm is much smaller, and
the 25-feet and 50-feet contour-lines are continuous with those of the
preceding basin. The 100-feet area is centrally placed in this arm, and
has a maximum depth of 137 feet. A small isolated 25-feet area lies to
the north-west of Eilean Dubh in this arm, with a maximum depth of
34 feet.

(3) The third basin in the north-western arm is the smallest and
shallowest of the three, and is cut off from the main basin by very

THE FRESH- WATER LOCHS OF SCOTLAND. 171

shallow water. The 25-feet contour-line follows approximately the
outline of the arm, and the 50-feet area is considerable, the maximum
depth being 66 feet in the eastern part of the basin.

The areas between the consecutive contour-lines, and the per-
centages to the total area of the loch, are as follows : —

0 to 50 feet 672 acres 50 '2 per cent.

50,, 100 „ 422 „ 31-7

100,, 150 „ 171 „ 127

150,, 200 „ 68 „ 5-0

Over 200 , 5 , 0'4

1338 ,, 100-0

Loch Skinaskink was surveyed on September 19 to 23, 1902. The
elevation of the lake-surface above the sea on commencing the survey
on September 19, 1902, was determined, by levelling from bench-mark,
as being 245*1 feet; when levelled by the Ordnance Survey officers on
August 13, 1870, the elevation was 242-7 feet above sea-level. The
highest drift-mark seen was 3J feet above the surface of the water.

Temperature Observations. — Temperature observations taken in the
deepest part of the loch at 4 p.m. on September 20, 1902, gave the
following results : —

Surface .. .. ... 54° '2 Fahr.

10 feet 54°-2 „

25 „ 54°-0 „

50 „ 54°-0 ,.

100 ,, 53°'3 ,,

125 „ 50°'l „

150 ,, .. .. 50°'0 ,,

170 , '. 49°-6 „

This series shows a range of temperature amounting to 40>6, the greatest
fall being one of 3°*2 between 100 and 125 feet.

172 BATHYMETRICAL SURVEY OF

LOCHS OF THE GARVIE BASIN.

THE lochs in this basin form a connected series, Loch Lurgain flowing
through Loch Bada na h-Achlaise (which was not sounded) into Loch
Bad a' Ghaill, thence by the Abhuinn Owskeich into Loch Owskeich,
which flows through the little Loch Garvie into Garvie Bay, an inlet
of Enard Bay. The lochs contain salmon and trout, but the fishing is
preserved.

Locli Luryaiii (see Plate XL.). — Loch Lurgain lies about two miles
to the south of Loch Skinaskink, and 3J miles south-east of Eiiard
Bay. The scenery around the loch is very fine, the serrated crest of
An Stac and the great pyramid-shaped mass of Cul Beag forming the
high ground to the north, while to the south rise Beinn Eun and
An t-Sail. The loch is crescent-shaped, with the concave side turned
towards the south. Very fine cliffs are formed in places, especially on
the southern shore to the west of the large islands, where for some
distance the cliffs are overhanging, and in one place there is a small
cave or recess in which 20 feet of water was found. On the opposite
northern shore are huge angular blocks which have slipped down from
above, one on top of the other, forming fine natural chambers. Loch
Lurgain is nearly 4 miles in length, the maximum breadth being over
half a mile, and the mean breadth one-third of a mile. Its waters
cover an area of 1J square miles, and it drains an area ten times
greater, or 12J square miles. Nearly 200 soundings were taken, the
maximum depth observed being 156 feet. The volume of water is
estimated at 2,139,752,000 cubic feet, and the mean depth at 61 feet.
The loch is divided into two basins by the large islands and the shallow
water between them. The eastern basin is the larger and deeper, and
quite simple in conformation. The 50-feet area is 2 miles in length,
extending from the narrow part of the loch at the south-east end to
north of the largest island. The 100-feet area is nearly 1J miles in
length, approaching to within less than a quarter of a mile from the
eastern point of the largest island. The 150-feet area is small and
centrally placed, and encloses the maximum depth of the loch (156
feet). In the eastern part of this basin are several rocky islets rising
from deep water to 1 to 3 feet above the surface. The western basin

THE FRESH- WATER LOCHS OF SCOTLAND. 173

is not quite so simple in conformation as the eastern one, the 100-feet
area having a central constriction in its outline with deeper water on
both sides. The 50-feet area is 1J miles in length, approaching to
within 200 feet of the western end of the loch. The 100-feet area is
nearly a mile in length, with a depth of 103 feet in the central con-
striction, deepening to 130 feet to the west, and 146 feet to the east,
of the constriction. The areas between the consecutive contour-lines,
and the percentages to the total area of the loch, are as follows : —

0 to 50 feet 352 acres 43 '6 per cent.

50,, 100 „ 306 ,, 38-0

100,, 150 „ 145 „ 18-0
Over 150 , 4 , 0*4

807 „ 100-0

Loch Lurgain was surveyed on September 5 and 9, 1902. The
elervation of the lake-surface above the sea could not be determined,
but when levelled by the Ordnance Survey officers on August 9, 1870,
the level was found to be 173-0 feet.

Temperature Observations. — Temperature observations were taken
in the deepest part of the loch at 3 p.m. on September 9, 1902, with
the following results: — •

Surface 56°'l Fahr.

50 feet 55°-5 ,,

100 , 52°-0 „

140 „ 50°-3 „

This series shows a range of temperature amounting to 50-8, there being
a fall of 3°-5 between 50 and 100 feet. The range was greater than
that observed in any other loch in the district, even in Lochs Assynt,
Skinaskink, and Bad a' Ghaill, which are all deeper than Loch Lurgain.

Lock Bad a' Ghaill (see Plate XLI.).— Loch Bad a' Ghaill (or
Baddegyle) lies immediately to the north-west of Loch Lurgain, with
which it is connected by the little Loch Bada na h-Achlaise, and about
1J miles to the south-east of Enard Bay. The ground to the north and
west is comparatively low, An Stac and An t-Sail rising to the east and
south. The loch is over 2 miles in length, with a maximum breadth of
three-quarters of a mile, the mean breadth being nearly half a mile.
Its waters cover an area slightly exceeding one square mile, and it
drains directly an area of 4| square miles, but since it receives the
outflow from Loch Lurgain its total drainage area is over 17 square
miles. Over 150 soundings were taken, the maximum depth observed *
being 180 feet. The volume of water is estimated at 1,767,582,000
cubic feet, and the mean depth at 62 feet. Loch Bad a' Ghaill is cut

174 BATHYMETRICAL SURVEY OF

into two deep basins by the shoaling of the bottom between the penin-
sula of Rudha Dubh on the southern shore and the island opposite to it
towards the northern shore, but even here there is a depth near the
centre of 72 feet, so that the 25-feet and 50-feet areas are continuous
from end to end of the loch. The 25-feet contour-line follows approxi-
mately the outline of the loch ; the 50-feet contour is extremely sinuous,
in some places following the outline of the loch and in other places,
especially in the central part of the loch, being far removed from the
shore-line. Of the two 100-feet basins the south-eastern one is the
larger and deeper, being over three-quarters of a mile in length, and
widest towards the centre of the loch, narrowing on approaching the
south-eastern prolongation. The maximum depth of the loch (180 feet)
was observed towards the south-eastern end of this basin, and about
200 yards from the north-eastern shore. The north-western 100-feet
basin is less than half a mile in length, with a maximum depth of
153 feet. Some of the lines of soundings show minor undulations of
the lake-floor, and in one case towards the north-western end a sounding
of 20 feet was recorded about 250 yards from the southern shore with
a depth of 80 feet between it and the shore ; this shallow sounding may
possibly be connected with the shallow water surrounding the large
island lying to the south-west. There are indications of moderately
steep slopes, especially along the south-western shore, where soundings
exceeding 40 feet were recorded in various places close inshore. The
areas between the consecutive contour-lines, and the percentages to
the total area of the loch, are as follows : —

0 to 50 feet 296 acres 45 '1 per cent.

50,, 100 „ 239 ,, 36-5

100., 150 ,, 100 „ 15-3 „

Over 150 , 21 3'1

656 „ 100-0

Loch Bad a' Ghaill was surveyed on September 18, 1902; the
elevation of the lake-surface above the sea could not be determined.

Temperature Observations. — Temperature observations taken at
5 p.m. in the deepest part of the loch gave the following results: —

Surface .. 54° '5 Fahr.

50 feet r>4°v> „

100 „ 50°-5 ,,

170 „ 50°'0 „

This series shows a constant temperature down to 50 feet, then a fall of
4° between 50 and 100 feet, the extreme range being 4°-5.

Loch Owskeich (see Plate XLL). — Loch Owskeich (or Oiskaig) lies
about a mile to the north-west of Loch Bad a' Ghaill, to which it is

THE FRESH- WATER LOCHS OF SCOTLAND. 175

connected by the Abhuinn Owskeich, and half a mile to the south of
Enard Bay, into which its waters are discharged by the river Garvie.
The ground around the loch is low, especially to the north and west.
The loch is over 1J miles in length, with a maximum breadth of three-
quarters of a mile, the mean breadth being less than half a mile. Its
waters cover an area of about 420 acres, or two-thirds of a square mile,
and it drains directly an area of about 3 square miles, but since it
receives the outflow from Lochs Bad a' Ghaill and Lurgain its total
drainage area is about 20 square miles — an area thirty-one times
greater than that of the loch. Over 100 soundings were taken, the
maximum depth observed being 153 feet. The volume of water is
estimated at 845,809,000 cubic feet, and the mean depth at 47 feet.
Loch Owskeich forms a simple basin, but the deep water approaches
very close to the south-eastern shore, off which the slopes are steep and
in striking contrast to the gentle slopes at the north-west end of the
loch. A sounding of 90 feet was recorded only 100 feet, and a sounding
of 120 feet only 200 feet, from the eastern shore, and the maximum
depth of the loch (153 feet) was observed about 300 yards from that
shore. At the opposite end of the loch the 25-feet contour-line is
distant 300 yards, and the 50-feet contour half a mile, from the north-
western shore. The 50-feet area is nearly a mile, and the 100-feet area
nearly three-quarters of a mile, in length. In the shallower water
towards the outflow one or two slight undulations of the lake-floor
were observed. The areas between the consecutive contour-lines, and
the percentages to the total area of the loch, are as follows : —

Oto 50 feet 280 acres 66 '3 per cent.

50 ,, 100 „ 82 „ 19-7

100 „ 150 „ 57 „ 13-7

Over l.>0 . I 0'3

420 „ 100-0

Loch Owskeich was surveyed on September 18, 1902 ; the elevation
of the lake-surface above the sea could not be determined, but when
levelled by the Ordnance Survey officers on July 8, 1870, it was found
to be 71-9 feet above sea-level.

Temperature Observations. — Temperature observations taken at
4 p.m. on September 18, 1902, in the deepest part of the loch gave the
following results : —

Surface .. 54°'8 Fahr.

50 feet .. 54° *2 ?,

100 „ 53°-7 „

130 ,, .. 50°-8 „

This series shows a range of 4°, the greatest fall being one of 2°-9
between 100 feet and the bottom.

176

BATHYMETRICAL SURVEY OF

The details regarding the lochs in the Inver, Roe, Kirkaig, Polly,
and Garvie basins are collected together in the following table for
convenience of reference and comparison. Where the elevation above
the sea was not determined by levelling from bench-mark, the
approximate elevation is given in brackets; in the case of Lochs
Urigill, Cam, Lurgain, and Owskeich, the Ordnance Survey level is
given with an indication of the date when levelled.

From this table it will be seen that in the twenty lochs under
consideration, 2540 soundings were taken, and that the aggregate area
of the water-surface is over 12J square miles, so that the average
number of soundings per square mile of surface is 200. The aggregate
volume of water contained in the lochs is estimated at about 20,355
millions of cubic feet. The area drained by these lochs is about 150J
square miles, or twelve times the area of the lochs.

THE FRESH-WATER LOCHS OF SCOTLAND.

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178 BATHYMETRICAL SURVEY OF

NOTES ON THE GEOLOGY OF THE ASSYNT DISTRICT.

By B. N. PEACH, LL.D., F.R.S., and J. HORNE, LL.D., F.R.S. With
Geological Map (Plate XLIL). Published by permission of the
Director of the Geological Survey.

From a geological point of view, the Assynt district is one of
the most interesting in the north-west Highlands. The various rock
formations which enter into the geological structure of the region are
there splendidly developed, and the evidence in proof of those great
terrestrial displacements of post-Cambrian date may be studied in
detail in the mountainous region that runs southward from Glas Bheinn
by Ben More Assynt and Breabag to the Cromalt Hills.

Beginning with the Archaean gneisses (gt on map), which may be said
to form the foundation-stones of that region, they are unquestionably
older than the succeeding great development of Torridon Sandstone
and overlying Cambrian strata. On referring to the geological map,
it will be seen that they occupy a belt of ground from 6 to 9 miles broad,
extending along the western coast-line between Enard Bay and Stoer,
thence inland to the base of the grand escarpment of Torridon Sand-
stone that stretches southwards from Quinag to the Coigach mountains.
These crystalline gneisses give rise to a type of scenery that is charac-
teristic of a large part of the western seaboard of Sutherland and Ross,
which seems to be typical of Archaean areas. Bare rounded knolls and
bosses of grey gneiss follow each other in endless succession, and in the
hollows there are numerous pools and lochs occupying rock-basins. The
whole tract occupied by these crystalline gneisses is singularly destitute
of drift. The rocky knolls do not rise much above one general level,
which does not as a rule exceed a few hundred feet in height, save near
the base of Quinag, Canisp, and Suilven, where the elevation of the old
gneiss plateau is about 1000 or 1250 feet.

The Archaean rocks of the Assynt district, west of the great
escarpment of Torridon Sandstone, consist largely of pyroxene gneisses
and ultrabasic rocks (pyroxenites and hornblendites), which still show
in a marked degree their original characters. Their behaviour in the
field and their appearance under the microscope have led to the
conclusion that they have affinities with plutonic igneous products.
All over that district, where the original characters have not been
effaced by later mechanical stresses, it is possible to trace the imperfect
separation of the ferro-magnesian from the quartzo-felspathic con-
stituents, the gradual development of mineral banding, and the net-like
ramifications of acid veins (pegmatite) in the massive gneiss. Whatever
be the origin of the mineral banding in these Archaean gneisses, it is

THE FRESH- WATER LOCHS OF SCOTLAND. 179

certain that they possessed this banding and were thrown into gentle
folds before the intrusion of the later dykes.

On referring to the map showing the surface geology of the Assynt
district, it will be seen that the Archaean area is traversed by narrow
dykes of igneous material (BG on map) trending west-north-west or
north-west. In certain belts they occur in great numbers, and their
intrusive character is clearly displayed. The dominant types in
the Assynt district comprise ultrabasic rocks (peridotite) and basic,
including dolerite and epidiorite. These dykes frequently form pro-
minent features in the landscape, sometimes giving rise to ridges and
sometimes to clefts or " slacks " in the midst of the surrounding gneiss.

A further important feature in the history of the Archaean gneiss
remains to be noticed, for, after the uprise of the great series of
intrusive dykes, the whole region was subjected to mechanical stresses
that profoundly affected the pyroxenic gneisses and the dykes which
traverse them. These lines of movement may be described as lines of
shearing or disruption lines, which trend in certain definite directions,
and give rise to molecular re-arrangement of the minerals and the
development of newer foliation both in the gneiss and in the dykes.
The gneisses are thrown into sharp folds, and are traversed by zones or
belts of secondary shearing, in which the pyroxenic rocks are converted
into bio tit e and hornblende gneisses. In like manner, the basic and
ultrabasic dykes appear frequently as phacoidal masses in the shear
zones, and where the latter coincide more or less with the original
trend of the dykes, or cross them, then the peridotite and epidiorite
intrusions are changed into talcose schist and hornblende schist
respectively. A glance at the Geological Survey 1-inch maps of the
Assynt district (Sheets 107 and 101) shows the great number of these
lines of movement. Further reference will be made to these features
in connection with the rock-basins of that district. At present it is
important to remember that all these movements took place before the
deposition of the Torridmi Sandstone.

This undulating plateau of Archaean gneiss was originally covered
by a vast pile of sandstones, conglomerates, and shales (Torridonian,
t on map), which has been largely removed by denudation. The
unconformability at the base of the Torridon Sandstone represents a
vast interval of time, during which the old land-surface of Archaean
gneiss was carved into hill and valley. On the north-west slope of
Quinag a remnant of this ancient topography is still to be found, where
a hill of crystalline gneiss rises to a height of 800 feet in the overlying
sandstone. One of the striking features in the landscape of that
region is the great western escarpment of Torridon Sandstone, reaching
in places an elevation of 1000 feet above the Archaean plateau. That
cliff is not continuous, for the sandstones on Quinag north of Loch
Assynt cannot be traced without a break to those of Cul Mor and Cul

180 BATHYMETRICAL SURVEY OF

Beag and of the Coigach mountains beyond. Though at the base there
is sometimes a local breccia that varies in character in accordance with
the underlying rocks, this pile of sediment mainly consists of a
succession of false-bedded grits and sandstones, with scattered pebbles
derived from formations which do not now occur in the west of
Sutherland and Ross. On Quinag and Beinn Gharbh the sandstones
have a gentle dip to the south of east, but on Suilven the strata are
horizontal, or nearly so. They attain a thickness of several thousand
feet, for in the Coigach mountains they rise from the shores of Loch
Broom to a height of about 2400 feet.

Overlying the Torridon Sandstone come the various subdivisions of
the Cambrian formation, comprising the basal quartzite (a1 on map),
pipe-rock (a2), fucoid beds (a3), serpulite grit and limestone (a4). The
detailed mapping of that region has proved that the Cambrian strata
are separated from the Torridon Sandstone by a marked uncon-
formability, It represents an interval of time during which the
Archaean floor and overlying Torridonian sediments were exposed to
denudation; a vast thickness of strata was removed, and in places the
Archaean gneisses were laid bare. Hence we find in the undisturbed
area clear evidence of the double unconformability of the Cambrian
quartzites on the Torridon Sandstone and Archaean gneiss. This
important geological feature is well displayed on the north slope of
Beinn Gharbh, south of Loch Assynt. The age of these sediments
has been proved by the discovery of trilobites and other organisms,
characteristic of the lower division of the Cambrian system, in the
fucoid beds of Sutherland and Ross. Fragments of these trilobites
have been found in this member of the series at BLnockan and on the
north shore of Loch Assynt.

On referring to the map, it will be seen that to the west of the
band of limestone (a4) extending from Inchnadamph to Knockan, the
Cambrian quartzites and fucoid beds have been traced across the sheet
from Loch Gainmheich to Strath Kanaird. On the eastern slopes of
Quinag, Canisp, and Cul Mor, the white quartzites form a thin cake
on the underlying Torridon Sandstone, which on some of the lofty
peaks is isolated by denudation. The quartzites dip at a higher angle
than the sandstone, and on descending the hill slopes the former pass
transgressively across bed after bed of the sandstone, and rest succes-
sively on lower members of the Torridon Sandstone.

One of the remarkable features of the Assynt district is the series
of intrusive igneous rocks of later date than the Cambrian limestone
and older than the post-Cambrian movements. In the undisturbed
area west of the great post-Cambrian displacements, they cover con-
siderable areas on Beinn Gharbh, south of Loch Assynt, where they
appear as sills in the Torridon Sandstone or Cambrian quartzite.
These sills can be traced round the western slopes of that hill, as well

THE FRESH- WATER LOCHS OF SCOTLAND. 181

as round the escarpments of Suilven and Canisp. But in the displaced
masses, east of a line extending from Inchnadamph to Knockan, the
intrusive rocks of this series have a much larger development and
greater variety. They appear at intervals over a tract measuring 12
miles from north to south, and from 5 to 6 miles from east to west.
The largest of these masses extends from Ledmore and Cnoc na Sroine
eastwards by Aultnacallagach towards Cnoc Chaoruinn, and another
important sheet runs north from Loch Ailsh to Loch Sail an Ruathair.
But throughout the mountainous region of Glas Bheinn, Ben More
Assynt, and Breabag these igneous rocks appear as sills in the" various
thrust-masses, restricted generally to certain definite horizons. A
glance at the map will show that they occur at the base of the Cambrian
quartzite, in the basal quartzite, in the pipe-rock, in the fucoid beds,
and also in the limestone. The mapping of these intrusive sheets has
shown the complicated character of the geological structure of that
region. The petrographical characters of these igneous materials have
been studied by Mr. Teall, and are of special interest. They comprise
the plutonic mass of Cnoc na Sroine and Loch Borralan, and the
numerous sills and dykes that traverse the Torridonian and Cambrian
sediments. The former seems to have resulted from the consolidation
of alkaline magmas rich in soda ; at the one end of the series there is
the quartz-syenite of Cnoc na Sroine, and at the other the basic augite-
syenite, nepheline-syenite, and borolanite. The sills and dykes include
two well-marked types — viz., hornblende-felspar rocks, and felsites with
alkali felspar and aegirine.

Before proceeding to the description of the eastern or Moine schists
(in on map), reference must be made to those terrestrial movements
which affected that region in post-Cambrian time, whereby the
Cambrian rocks were piled on each other, and huge slices of the floor
of Archaean gneiss with the overlying Torridonian and Cambrian
sediments were driven westwards and made to override the underlying
piled-up strata. The structure is admirably shown in the horizontal
section extending from Quinag to the river Cassley, placed below the
map, showing the surface geology of the Assynt district. On referring
to that section, it will be seen that at its western limit on Quinag,
where the rocks are undisturbed, the Torridon Sandstone rests on a
highly eroded platform of Archaean gneiss, being itself unconformably
overlaid in turn by the Cambrian quartzites, fucoid beds, and serpulite
grit (3, 4, 5, and 6 in section). In the valley of the Skiag, north of
Loch Assynt, the first disruption line or thrust-plane is met with, above
which lie various members of the Cambrian system, chiefly the fucoid
beds, serpulite grit, and limestone, with their accompanying intrusive
sheets of igneous material, all of them being driven together by minor
thrusts or reversed faults or folds.

Crossing the limestone plateau at Achumore to the western base

182 BATHYMETRICAL SURVEY OF

of Glas Bheinn, we encounter the Glencoul thrust (T in section), the
first of the series of powerful displacements in the Assynt region.
Overlying this plane there is a mass of Archaean gneiss, covered un-
conformably by both divisions of the Cambrian quartzite with their
characteristic igneous sills. Along the western slope of Glas Bheinn
the quartzites are inverted, but the sequence can be interpreted by
means of the subdivisions of the pipe-rock, based on the characters
of the worm-casts from which that zone derives its name. Eastwards
we find the Poll an Droighinn thrust (T' in section), and still further
east, beyond Loch Cuaran, the Ben More thrust (T" in section). By
means of these displacements, additional slices of the Archaean floor
with the overlying Cambrian sediments and intrusive sheets have been
driven westwards like the materials above the Glencoe thrust-plane.
The visitor to that district may study the relations of the Ben More
thrust-plane and the materials above and below it on the southern
slope of that mountain in the Beallach (pass) of Coniveall. A con-
siderable thickness of Torridon Sandstone there intervenes between the
Archaean gneiss and the Cambrian quartzites, which does not appear
in the line of section further north between Quinag and the river
Cassley. Indeed, on Ben More Assynt, the double unconformability
of the Cambrian quartzite on the Torridon Sandstone and the Archaean
gneiss is well seen. In the deep corries on the south side of Ben More
Assynt, the observer finds a great development of the Lewisian gneiss
with its dykes of epidiorite, forming a rocky slope about 1000 feet high,
which presents many of the characteristic features of the old Archaean
floor west of Quinag. Eastwards again, towards the river Cassley,
beyond the Cambrian quartzites, fucoid beds, serpulite grit, and
limestone, appears the Moine thrust, which brings forward a great
succession of crystalline schists (Moine schists, M in section), to which
reference will immediately be made.

One of the romantic features of the geology of the Assynt region is
the isolation by denudation of materials overlying the Ben More thrust-
plane. Two outliers of this nature occur west of Breabag, on Beinn
nan Cnaimhseag and Beinn an Fhuarain, where slices of Torridon
Sandstone and basal Cambrian quartzite overlie Cambrian limestone.
Indeed, in the more southerly mass (see map) a small core of Archaean
gneiss with an intrusive dyke of epidiorite appears in the midst of the
younger formations. These outliers clearly point to the original
westward extension of the materials overlying the Ben More thrust-
plane having been separated from the main mass east of Breabag by
prolonged denudation. It is worthy of note that, though the structure
of the disturbed area in the mountainous region of Assynt is highly
complicated, still by the zonal mapping of the various rock groups,
the relations of the displaced materials can be satisfactorily determined.

The Moine thrust (TIV in section) is the most easterly of the great

THE FRESH- WATER LOCHS OF SCOTLAND. 183

post-Cambrian displacements that affected that region, the outcrop
of which is somewhat remarkable. On referring to the geological map,
it will be seen that it can be traced from Loch nan Caorach and Gorm
Loch Mor east of Glas Bheinn, southwards along the eastern base of
the Ben More group of mountains to Loch Ailsh, thence across the
Oykell to the Cromalt hills. Here the outcrop of the thrust-plane
changes its course, and runs west along the base of these hills to
Knockan, a distance of 6 miles, whence it runs southwards to Strath
Kanaird. It will thus be seen that there is an extraordinary overlap
of the Moine thrust-plane along the base of the Cromalt hills, for it
passes transgressively across the Ben More thrust-plane and all
underlying thrusts till the materials overlying it rest directly on the
undisturbed Cambrian strata south of Knockan.

Near the Moine thrust the new structures resulting from the post-
Cambrian movements are well developed. The lenticles of Lewisian
gneiss and pegmatite are sheared and rolled out, the former passing
into flaser gneiss and schist, and ultimately into a banded platy schist,
while the latter show fluxion structure with felspar " eyes " like
rhyolites. The Torridon Sandstone and Cambrian quartzites, the
fucoid beds and intrusive igneous sheets, are likewise sheared and
rolled out, the new divisional planes being more or less parallel to that
of the Moine thrust. Indeed, such is the transformation effected by
these movements on the crystalline rocks and overlying sediments,
that it is often difficult to determine the original characters of the
component members. It is noteworthy, however, that all the crushed
or mylonised rocks near the Moine thrust show a characteristic striping
on the divisional planes due to orientation of the constituents in the
direction of movement.

The strata overlying the Moine thrust-plane and stretching east-
wards down the Cassley and the river Oykell and across the Cromalt
hills are remarkably uniform in character. They consist to a large
extent of flaggy quartzose schists, with partings and bands of mica-
schists and occasional intrusive sheets or sills of igneous material which
have a common foliation with the schists. The matrix of the quartz-
schists is holo-crystalline and forms a granulitic mosaic, which is
perhaps the characteristic feature of the group. Occasionally "eyes"
of felspar appear in the schists, when the rocks might be described as
flaser schists. There can be little doubt that the Moine schists are to
a large extent, if not wholly, altered sediments, the age of which is
still uncertain. Any one who has examined the Archaean rocks in
the undisturbed area west of the Torridon Sandstone escarpment, has
no difficulty in distinguishing the pyroxenic gneisses and intrusive
dykes from the quartz-schists and mica-schists of the Moine series.
These broad lithological distinctions have been of great service in
interpreting the history of the glaciation of that region.

184 BATHYMETRICAL SURVEY OF

The Assynt district furnishes impressive evidence of denudation by
the removal of a vast covering of Torridon Sandstone, by the persistent
eastward recession of that escarpment, by the stripping off of the
materials overlying the successive thrust-planes, and also by the
development of the present drainage system. It is a remarkable fact
that south of the mountainous region of Assynt the watershed lies to
the east of Cul Mor, Cul Beag, and the Coigach mountains in the less
elevated platform of the Moine schists. It is evident that the present
drainage system originated at a remote geological period, when the
eastern or Moine schists extended far to the west of their present
limits, and were arranged in the form of a dome round the displaced
masses which now form the mountainous region of Assynt. It is highly
probable, also, that before the glacial period the land stood relatively
higher than at present, and that the rivers on the west side of the
watershed occupy consequent valleys which extended far to the west
of the present coast-line.

Everywhere throughout the Assynt district, and especially in the
mountainous region extending from Glas Bheinn to the Coigach area
and over the plateau of Archaean gneiss, there is conclusive evidence of
intense glaciation. Perhaps the most striking feature of the glacial
phenomena of Assynt is the evidence pointing to the conclusion that
during the maximum glaciation the ice-shed did not coincide with the
existing watershed. From an examination of the striae indicating the
direction of the ice-flow, and from the distribution of boulders, it
appears that the ice-parting lay to the east of the present watershed.
Indeed, the ice must have accumulated to a great thickness on the less
elevated plateau occupied by the Moine schists east of the Ben More
Assynt range and east of the Coigach mountains.

The general movement of the ice at great elevations in this district
was in a westerly direction, sometimes to the north and sometimes
south of that point. For example, on Glas Bheinn, on one of the
exposures of Archaean gneiss, at a height exceeding 2000 feet, the
striae point W. 5° N. Again, on Beallach an Uidhe, between Glas
Bheinn and Beinn Uidhe, at an elevation of about 2000 feet, the
direction is west-south-west. East of Inchnadamph, on the quartzite
of Beinn an Fhurain, between the 2000- and 2250-feet contour-lines,
the striae run north of west. In the lofty pass crossing the Ben More
range, that leads into Corrie Mhadaidh, at a level of 2750 feet, the
direction is W. 10° S. or W.S.W. In like manner, on the long ridge
of Breabag that runs northward from the Beallach of Coniveall, the
average height of which is over 2000 feet, splendidly striated surfaces
have been recorded which indicate an ice-movement in a westerly
direction.

Passing westwards to the mountains north and south of Loch
Assynt, we find similar evidence of a westerly movement during the

THE FRESH- WATER LOCHS OF SCOTLAND. 185

maximum glaciation. On Quinag, at an elevation of 1750 feet, the
striae point W. 5° N., and on Beinn Garbh near the top, about the
1500-feet contour-line, the direction varies from W. 10° S. to W.S.W.
On the eastern slope of Canisp, between the 1250- and 1500-feet
contour-lines, on polished surfaces of quartzite, the striae point north
of west, indicating an ice-movement up the slope in the direction of
the Archaean plateau. On the flanks of Suilven, below the limit of the
Torridon Sandstone, the striae trend about west-north-west. Further
south, on Cul Mor, near the 1500-feet level, on the top of the escarp-
ment of Torridon Sandstone east of Loch Skinaskink, the direction is
a few degrees south of west.

The general westerly movement of the ice across the mountainous
part of Assynt, the Cromalt hills, and the Coigach district is confirmed
by the dispersal of the boulders. Indeed, the evidence on this point is
somewhat remarkable. For instance, on Beinn an Fhurain, which is
composed of displaced members of the Cambrian formation, quartzites,
fucoid beds, and serpulite grit, boulders of thrust Lewisian gneiss
occur on the crest of the ridge, which have been borne westwards from
the deep corries north of Ben More Assynt. The highest elevation of
the thrust Lewisian gneiss in Corrie Mhadaidh is from 1750 to 2250
feet, and the striae on the quartzite ridge of Beinn an Fhurain west of
that corrie point W. 10° to 20° N. Further north, on Mullach an
Leathaid Riabhaich, similar boulders of thrust Lewisian gneiss rest
on the quartzite at a height of 2250 feet. On Breabag the evidence is
no less remarkable, for on the quartzite ridge that runs southwards
from Breabag Tarsuiim (2044 feet) about the 2000-feet level, numerous
blocks of thrust gneiss and Moine schist have been recorded. Further
south along the same ridge, in the direction of Meall Diamhain, on
the outcrop of fucoid beds as well as on the quartzites, blocks of thrust
gneiss and granulitic quartz-schist are met with. The boulders of
thrust gneiss have been derived from the belt of this material that has
teen traced continuously from Ben More Assynt south to Sgonnan Mor,
while the blocks of granulitic schists have been carried westwards from
the Moine schist area, the average height of which is lower than that
of the Breabag ridge. It follows, therefore, that during this westerly
movement the Moine schist erratics must have been borne to levels at
least 500 feet higher than the sources from which they were derived.

When we pass beyond the limit of the Ben More group of mountains
to Cul Beag (2523 feet) — a mountain of Torridon Sandstone west of the
Cromalt hills — the evidence is equally conclusive regarding the trans-
port of materials in a westerly direction to higher levels. For there,
at a height of 2300 feet, blocks of Moine schist rest on the Torridon
Sandstone. Comparing the elevation of the Cromalt hills between
Coigach and the river Oykell with the height of these erratics on Cul
Beag, it is obvious that the latter must have been raised about 600 feet

186 BATHYMETRICAL SURVEY OF

in the course of the movement. On Cul Mor, north of Cul Beag, our
colleague Mr. Hinxman found a boulder of nepheline-aegiriiie syenite
just below the 2000-feet contour-line, which must have been derived
from the Cnoc na Sroine and Aultnacallagach igneous mass (see
Geological Map). No part of that mass reaches an elevation greater
than 1306 feet, so that this boulder, during the westerly movement of
the ice, must have been raised at least about 600 feet above its parent
source.

There is hardly any trace of boulder clay within the mountainous
part of Assynt. This deposit appears in some of the valleys occupied
by the Moine schists, as for instance, in the catchment basins of the
Cassley and the Oykell, and in the valleys of the Cromalt hills. The
drift deposits consist chiefly of moraines which have indeed a wide
distribution. An examination of the moraiiiic material, and of the
boulders on the mounds, points to a period of confluent glaciers when
the mountainous part of Assynt, together with the Cromalt hills,
Cul Mor, Cul Beag, and the Coigach mountains, became independent
centres of dispersion. The feathered arrows on the geological map
indicate this later movement, and show a marked contrast from the
persistent westerly trend of the earlier glaciation. A glance at the
map will show, for instance, how from the north-east slope of the
Glas Bheinn and Ben More Assynt range the later ice spread over the
moorland plateau east of Gorm Loch Mor and Fionn Loch Mor onwards
in the direction of Loch Shin. This plateau is covered with moraine
mounds which contain boulders and debris of Cambrian quartzite,
borne from the mountains to the west on to the area occupied by the
Moine schists. Again, in the valley of the Cassley that drains the
great corries east of Ben More Assynt and Carn na Convaroan, boulders
of Cambrian quartzite have been traced for about 15 miles down to
Invercassley. Again, on the Moine schist plateau east of Loch Ailsh
and south-east of Sgonnan Mor, moraines occur containing blocks
of Cambrian quartzite and thrust Archaean gneiss from that area.
Further, on the west side of Glas Bheimi and Ben More Assynt, in
the neighbourhood of Inchnadamph, part of this confluent glacier ice
streamed northwards up the Skiag valley, carrying boulders of the
intrusive porphyrite of Beinn Gharbh in its train. Local ice streamed
off the eastern slopes of Canisp and Beimi Gharbh, which coalesced with
that radiating from Breabag. In like manner, from the eastern slopes
of Cul Mor and Cul Beag, local glaciers diverged which united with
that moving off the Cromalt hills, and were deflected westwards towards
the Archaean plateau and northwards towards Strath Kanaird.

On referring to the geological map, it will be seen that most of the
lochs lie within the area occupied by the Archaean gneiss. As the
region is remarkably free of drift, the lochs lie in hollows in the solid
rock, and are therefore rock-basins. Indeed, any one who visits the

THE FRESH- WATER LOCHS OF SCOTLAND. 187

area cannot fail to be struck with the number and irregular outlines
of the lakes in the plateau of Archaean gneiss. While mapping that
region, it was obvious that the direction of many of the lochs and of
their branches had been largely influenced by the trend of lines of
shearing and lines of fault, by the trend of groups of intrusive dykes,
and by the presence of ultrabasic masses, which weather more readily
than the pyroxenic gneiss. In view of these facts, the irregular contour
of the lakes on the Archaean plateau, as proved by the soundings, is
what might naturally be expected.

Loch Assynt. — This is the largest and by far the most important
lake in the Assynt district. Round the upper end and along the
north-east shore from Inchnadamph to the southern base of Quinag,
it is floored by Cambrian and Torridonian strata, while the remainder
rests on the Archaean gneiss plateau. It lies along an old consequent
valley, the origin of which dates back to a time when the surface
configuration was very different from what it is now. Originally, the
lake was of larger dimensions, for at its upper end it has been silted up
by the river Loanan; indeed, in that direction it must have extended
at one time almost to Stouechrubie. At its lower end it must formerly
have continued down to the narrows above Inveruplan — a distance of
over two miles from the foot of the loch, where a rocky barrier of gneiss
and intrusive dykes crosses the river Inver. From that point upwards
to the present lower limit of the lake an alluvial terrace is traceable,
through which the river follows a winding course. During its former
extension, Loch Assynt must have been continuous with Loch Uidh na
Geadaig and Loch Leitir Easaich.

The soundings show that this rock-basin is comparatively uniform.
The 50-feet contour-line runs from the present lower limit of the lake
to near the mouth of the river Loanan ; the 100-feet contour-line, from
the bend at Loch Leitir Easaich to near the schoolhouse at Inchna-
damph—a distance of 5 miles; the 150-feet contour-line is continuous
from a point opposite Tomore to near the schoolhouse at Inchnadamph,
thus forming one basin 4| miles long. Five basins are enclosed by
the 200-feet contour-line, and three basins by the 250-feet line. The
height of the surface of the lake above sea-level is 215 feet, and the
greatest depth is 282 feet, within the Archaean area near Tobeg and
Eilean Assynt. At that point the lake is 67 feet below sea-level. A
glance at the bathymetrical map will show that the long axes of the
deeper basins coincide with the trend of the loch between Loch Leitir
Easaich and Inchnadamph, and that they lie nearer the southern shore.
This feature is worthy of note, as it is a continuation of an important
fault which has been traced for miles along Glen Salach in a north-
west direction, in the line of which lie several lakes (see Geological
Map). It must be borne in mind, however, that this line of disruption,
which has produced brecciation of the Archaean gneiss and dykes along

188 BATHYMETRICAL SURVEY OF

Glen Salach, is of pre-Torridonian age, and has no connection with the
later post-Cambrian movements. It developed a line of weakness,
which, when stripped of the overlying Torridon Sandstone and
Cambrian strata, would aid erosion either by the action of running
water or land ice. Several faults enter the lake on the south side
between Tobeg and Rudh' an Alttoir, which, trending in a north-east
direction, are coincident with inlets at the margin. Indeed, it is not
improbable that the sudden deflection of the lake between Loch Assynt
Lodge and Little Assynt — its course there being south-west and north-
east— may be due to faults in the same direction, entering the lake at
Little Assynt.

Loch Leitir Easaich. — This is a shallow rock-basin on the Archaean
plateau, which, as already indicated, was originally an arm of Loch
Assynt. Its long axis, trending north-west, coincides in direction with
that of the Glen Salach fault, but the deepest sounding — 70 feet —
does not lie in the line of this pre-Torridonian dislocation, but in a
small basin to the south of it.

Loch Beannach is another shallow rock-basin on the Archaean gneiss
with very irregular outlines, its greatest depth being 38 feet. Numerous
rock knobs project above the surface of the water. The long arm
trending north-west to Loch an Dubh Uidh coincides in direction with
an epidiorite dyke and with a line of disruption, but the numerous
small bays reflect the varying lithological characters of the Archaean
gneiss.

Loch Druim Suardalain and Loch na Doire Daraich are two shallow
rock-basins lying in the consequent valley of the Glen Canisp river
(Amhainn na Clach Airidh). A chain of small lakes lies along this
ancient valley, all of which are rock-basins now in course of being
silted up. The greatest depth of Loch Druim Suardalain is 31 feet.
Several small faults cross this lake in a north-east direction, which
produce a slight displacement of the intrusive dykes, but they do not
seem to have modified the floor of the loch as indicated by the
soundings. Loch na Doire Daraich is only about 9 feet deep.

Loch Crocach and Loch an Tuirc are likewise shallow rock-basins on
the bare Archaean floor. The long axis of the former loch, which is
about 1^ miles in length, lies in the line of a well-marked fault which
has been traced for miles across the Archaean plateau. There can be
little doubt that the straight feature of the west shore is due to this
dislocation. Numerous roches moutonnees rise above the surface of the
lake towards the east side. Again, in the case of Loch an Tuirc, a
fault which shifts the intrusive dykes enters the lake at its outlet, and
crosses it in a north-easterly direction. The straight feature on the
south side coincides with a zone of newer shearing in the Archaean
gneiss trending east and west.

Loch Veyatie and Fiotin Loch. — These lakes lie in rock-basins in the

THE FRESH- WATER LOCHS OF SCOTLAND. 189

direction of an old consequent valley traversing the Archaean plateau
and the Torridonian and Cambrian strata north-west of Elphin. These
lakes were evidently at one time connected, for an alluvial terrace
stretches up the valley from the Fionn Loch to near Loch Veyatie. The
height of the surface of the Fionn Loch is 357 feet above sea-level, and
the height of the alluvial terrace is 379 feet, so that the lake has been
lowered by about 20 feet. The long axis of this lake coincides generally
with the strike of the original banding of the Archaean gneiss, which
there dips to the south-west at angles varying from 20° to 30°. Several
large intrusive dykes trend obliquely up the loch, and lines of newer
shearing enter the lake on the north-west side, trending north-west.
Indeed, these shear lines have evidently determined the arm of the
lake that runs westwards beyond the point where the river Kirkaig
drains this sheet of water. Though of irregular contour, the soundings
show that it is a long narrow basin, the deepest sounding being 90 feet.

In like manner, though Loch Veyatie is 4 miles long, the soundings
show that it is a comparatively shallow basin, the deepest sounding
being 126 feet north of Loch a' Mhiotailt and near the foot of the
loch. The long axis of this lake is oblique to the strike of the early
foliation of the Archaean gneiss, and several large intrusive dykes enter
the foot of the lake, the direction of which coincides with that axis.
The upper part of the lake is floored partly by Cambrian and partly
by Torridonian strata, the lofty mountain of Cul Mor rising to a
height of 2786 feet on the south side. The soundings show that there
are three small basins, each over 100 feet in depth, two of which lie
north-north-east of the great escarpment of Torridon Sandstone of Cul
Mor, and the third near the foot, opposite an escarpment of Archaean
gneiss which rises to a height of 200 feet above the level of the lake.

Loch a' Mhiotailt is an arm of Loch Veyatie, near the foot of the
latter, and on its south side. The deepest sounding is 69 feet. The
long arm of the lake has evidently been determined by faults which
shift the outcrops of the intrusive dykes.

Loch Cam flows into Loch Veyatie at its upper end, near Elphin.
The western portion of this lake is floored by Archaean rocks, and the
central and eastern portions by Torridonian and Cambrian strata.
The soundings show that it is a comparatively shallow rock-basin.
Much of the east part near Elphin is under 50 feet in depth, and the
deepest soundings recorded at two localities further west are 122 feet.
One of these localities is at the narrows, where the lake is floored by
Cambrian quartzite, and the other about two-thirds of a mile from the
head on the Archaean plateau. The soundings further show that near
the head of the lake on the south-west side there is a narrow basin
trending nearly west-north-west, enclosed by the 100-feet contour-line,
the direction of which coincides with a line of pre-Torridonian shearing
that has been traced for miles to the west-north-west into the Fionn

190 BATHYMETRICAL SURVEY OF

Loch. The soundings also prove that there is a steep cliff along the
south shore parallel to this line of shearing, which is continued west-
north-west beyond the lake towards the Fionn Loch.

Of all the lakes within the Archaean plateau, Loch Skinaskink
presents the most irregular outlines. Still, it is obvious that its
southern portion lies along a consequent valley, which rises between
Cul Mor and Cul Beag. The lake is now drained by the river Polly,
which, where it leaves the loch, flows over a barrier of Archaean gneiss.
The longer axis of the loch south-west of Eilean Mor coincides with the
trend of the early foliation of the gneiss and of certain intrusive dykes.
The north-west margin of the loch has been determined by a pre-
Torridonian line of fault, which shifts the outcrops of the intrusive
dykes.

Numerous rocky islets rise above the level of the loch, which,
together with the soundings, reflect the varying character of the
Archaean gneiss and intrusive dykes. Various faults enter the loch,
which in many cases have given rise to well-marked inlets. The deepest
sounding is 216 feet, which occurs not far to the south of Eilean Mor,
in the line of the longest axis from south-east to north-west, and
where that axis is intersected by a north-east and south-west fault.

Loch Lurgain lies wholly within the Torridon Sandstone area, and
is a true rock-basin, for at its outlet it flows over a barrier of rock into
Loch Bada na h-Achlaise. The trend of the upper part obliquely
crosses the strike of the Torridon Sandstone, while that of the lower
is more or less parallel to it. About midway down the loch, roches
moutonnees appear, and the soundings there vary from 20 to 56 feet.
Above these islands there is a simple basin, the deepest sounding being
156 feet north-east of Beinn Eun. Below the islands the basin is
comparatively simple, the greatest depth being 148 feet. At the foot
of the loch, immediately in front of the rocky barrier, the basin
enclosed by the 100-feet contour-line is broader than further up the
lake.

Loch Bad a' Ghaill is a true rock-basin, which, save at its lower
end, where the rocky barrier is composed of Archaean gneiss, is floored
by Torridon Sandstone. The soundings show that this lake forms two
well-marked basins. The greatest depth of the upper one is 180 feet,
which is a few feet below sea-level, and the deepest sounding of the
lower basin is 153 feet. The ice-movement, as indicated by the striae,
seems to have coincided generally with the direction of this lake and
Loch Lurgain. Morainic drift is met with at intervals along the shores
of these lakes.

Loch Owskeich is likewise a rock-basin, the barrier being formed of
Torridon Sandstone. The loch, save at its upper end, where there
is a ridge of Archaean gneiss, is floored by Torridon Sandstone. The
soundings show that this lake has been modified by a powerful north-

THE FRESH- WATER LOCHS OF SCOTLAND. 191

north-east and south-south-west fault skirting the eastern shore,
whereby the Torridon Sandstone has been thrown down against the
Archaean floor on the east side. A glance at the map will show how
the contour-lines run parallel to that fault and close to the shore,
and that the deepest sounding, 153 feet, is not far from the line of this
dislocation.

Loch Urigill and Loch Maol a' Choire are shallow rock-basins in the
Cambrian limestone, the erosion of which may be partly due to
solution.

Loch Borralan lies along the line of a consequent valley, near the
headwaters of the river Kirkaig, and probably not far from the
original axis of uplift in early Palaeozoic times. It is a shallow rock-
basin, floored by igneous rocks which belong to the igneous mass of
Cnoc na Sroine, with some drift along its margin.

From the evidence now adduced, it is obvious that the plateau of
Archaean gneiss with its intrusive dykes is dotted over with lakes of
various sizes, which, with the exception of the lower part of Loch
Assynt, are of moderate depth. Indeed, most of them are shallow
basins, which reflect the varying types of gneiss and intrusive dykes
and their subsequent deformation. It is, no doubt, true that the
numerous shear-lines and faults of pre-Torridonian age that traverse
the Archaean plateau have determined to some extent the features of
these lakes; but we are, nevertheless, of opinion that the evidence
taken as a whole is in favour of the theory that they have been mainly
produced by the erosive action of ice.

NOTES ON THE BIOLOGY OF THE LOCHS IN THE ASSYNT DISTRICT.
By JAMES MURRAY.

Only an incomplete sketch can be given of the biology of this
district, as collections of plankton were made in only twelve out of the
twenty lochs surveyed. Loch Assynt is the largest loch in the district,
but four others, viz., Lochs Lurgain, Skinaskink, Bad a' Ghaill, and
Owskeich, are moderately large and of considerable mean depth, so
that they fall to be classed rather with the large lochs than with
the small ones. The remainder are small or of low mean depth.

The fauna of the plankton was very uniform throughout these lochs,
differing chiefly in the presence in some of them of one or other of the
northern species of Diaptomus, D. Wierzejskii, I), laciniatus, in the
Daphnia being D. lacustris in some and D. galeata in others, and in
the greater abundance of Rotifera and Rhizopods in the shallower
lochs. Though the three common Scottish species of Diaptomus were

192 BATYHMETRICAL SURVEY OF

found in the district, they were never all found together in one loch,
as was commonly the case elsewhere in Sutherland. The Daphnia in
most of the lochs was the typical D. lacustris. In one loch this was
associated with D. galeata, while in three lochs D, galeata was alone
observed. Leptodora was only observed in Loch Skinaskink, and
Bythotrephes was not observed at all.

While the fauna thus offers little that is remarkable, the flora, on
the other hand, is notable for the great wealth of Algae, especially of
Desmids. Over fifty species of Desmids were observed, and between
thirty and forty of these sometimes occurred in one loch. Messrs.
West, commentii^g on the Desmid flora of this part of Scotland, state
that the plankton is unique in the abundance of its Desmids, and that
the most conspicuous of these are of a distinctly western type, being
found in Europe only along the extreme north-western coasts, while
in North America they are eastern species. The southern and eastern
limits of this remarkably rich area in Scotland cannot yet be fixed;
in Sutherland it extends right across Scotland. An examination of
many hill lochs in Perthshire and in the south of Scotland showed no
such rich flora there. When the distribution of the Desmid flora is
worked out, it will be of interest to observe whether the area covered
by those western species coincides with that occupied by the northern
Calanidae, Diaptomus Wierzejskii and D. lacintatus, which are so
generally distributed in Sutherland, though they also occur in many
spots further south.

Loch Assynt. — The plankton of this loch closely resembles that of
the larger lochs in the south, only the typically pelagic Entomostraca
and Rotifera being present. It is noticeable that neither Diaptomus
Wierzejskii, D. laciniatus, nor Daphnia galeata, species widely dis-
tributed in the district and also occurring in many of the large lochs
further south, was observed here. The loch further resembles many
other large lochs in the presence of numerous skeletons of Clathrulina
elegans. The only Rotifer calling for mention is Triarthra longiseta,
a species not usual in large lakes. Unlike the other lochs of the
district, there were very few Desmids in the plankton. The quantity
of plankton was very small.

Loch Lurgain. — The fauna comprised only the usual pelagic species,
among which Cyclops strenuus was most abundant. The Daphnia was
D. galeata. Diaphanosoma brachyurum was present in some numbers.
The flora was remarkable for the number of Desmids, especially of the
genus Staurastrum, including the beautiful large species, S. longis-
pinum and S. arctiscon.

Loch Bad a' Ghaill. — The somewhat meagre plankton was almost
exactly of the type found in deep lochs, differing only in the greater
abundance of Rotifera, among which were Plcesoma, Gastropus, and
Triarthra. The commonest animal was Cyclops strenuus. About a

THE FRESH- WATER LOCHS OF SCOTLAND. 193

dozen species of Desmids were observed, including Staurastrum longis-
pinum and S. gracile, var. bulbosum.

Loch Owskeich. — The fauna was much richer than that of Loch
Bad a' Ghaill, with which, from position and size, it is best comparable.
Diaptomu* yracilis and D. laciniatus were both present. The Daphnia
was D. galeata. There were many filamentous Algae and Desmids,
among which occurred Staurastrum Brazil iense.

Loch Skinaskink. — The plankton was very rich, and, notwithstanding
the large size and considerable mean depth of the loch, resembled that
of a shallow loch in the great numbers of Rotifers, Desmids, and
Protozoa. There were two species of Diaptomus, D. gracilis and D.
laciniatus, and two of Daphnia, D. lacustris and D. galeata. Among
the Rotifera were two species which, though pelagic, are not usual in
large lakes, viz., a Synchceta and a Plcesoma. The Desmids included
Staurastrum Brazil ie?ise and S. ophiura.

Loch Fionn. — This loch, though long, is so narrow as to be little
more than an expansion of the river. When in spate, as on the occasion
of the visit of the Lake Survey, there is a decided current down the
loch. As would be expected in the circumstances, life was very scarce
and of few species. Two forms of Bosmina were present, B. obtusirostris
and its variety B. longispina.

Loch an Tuirc. — Entomostraca were numerous, but of few species.
Rotifera were scarce. Filamentous Algae were abundant, but there
were few Desmids.

Loch Beannach. — Organisms were not very abundant. Only the
commonest pelagic Entomostraca were present. Rotifera were more
numerous, including, in addition to the usual pelagic species, Gastropus
stylifer and a species of Plcesoma.

Loch na Doire Daraich. — The very abundant fauna of this loch
closely resembled that of the adjacent Loch Druim Suardalain, the
most notable difference being the more numerous Rotifera. Among
these were Floscularia pelagica, Triarthra longiseta, Pterodina patina,
Copeus cerberus, Dinocharis Collinsii. Among the numerous Desmids
were Micrasterias furcata, M. j)innatafjda, Staurastrum grande, and
S. longispinum.

Loch, Druim Suardalain. — This shallow loch had the richest fauna
found in the lochs of the district. The flora was also very rich. About
a dozen species of Rotifera were seen, including Callidina Brycei.
Over thirty species of Desmids occurred, among which were Staurastrum
grandr, S. ophiura, and S. serangulare. There was nothing among
the Entomostraca calling for remark, only the commoner pelagic and
shallow-water species being observed.

Loch Maol a' Choire. — Crustacea were very abundant, including a
species of Gammarus. Diaptonnis Wierzejskii was the only Calanid
observed. It was in a collection from this loch that the species was

o

194 BATHYMETRICAL SURVEY OF

discovered in Britain by Dr. Scott. The usual pelagic Rotifera were
present. No Desmids were seen.

Loch Awe. — The most abundant organism was a variety of Diaptomus
Wierzejskii. Sida was seen here, and in no other lake in the district,
being somewhat late in the season for this species. Very few Rotifera
or Algae were noticed.

THE FRESH-WATER LOCHS OF SCOTLAND. 195

LOCHS OF THE MORAR, BASIN.

THREE lochs lying in the basin of the river Morar were surveyed —
viz., Loch Morar, Loch Beoraid, and Loch an Nostarie. There are
a number of other small lochs in this catchment-basin, but as there
were no boats on them they could not be surveyed. Loch Morar is the
principal loch in the basin, and it gives great interest to the whole
area from the fact that it is not only the deepest lake in Scotland, but
in the British Islands ; indeed, the bottom of this loch forms the deepest
hole in the continental plateau on which our islands are situated.

From the accompanying sketch-map (Fig. 32), it will be seen that
Lochs Morar and Beoraid are parallel to each other, and run in an east-
and-west direction. The overflow from Loch Beoraid, which lies about
3 miles to the south of Loch Morar, enters Loch Morar about its centre
by the river Meoble, while the overflow from Loch an Nostarie, which
lies to the north, enters Loch Morar at its western end by the river
Loin.

The west end of Loch Morar is only about 500 or 600 yards from
the sea, and its outflow is by the river Morar, which in its course falls
over a rocky barrier, at the foot of which is a famous salmon pool.

The total drainage area of the Morar basin is calculated at 42,000
acres, or over 65J square miles. The whole region is rocky and
mountainous. The district has not yet been mapped by the Geological
Survey, but it is believed that the whole basin lies entirely in the
crystalline schists of the Moine series of the Geological Survey, the
main strike being north-north-east to south -south-west. The rocks
seen at the barrier at the mouth of the loch are composed of hard
quartzose flagstones or siliceous Moine schists. The direction of the
hills at the belt which separates Loch Morar from the sea agrees
generally with the strike of the rocks. Lochs Morar and Beoraid
occupy true rock-basins, but it seems almost certain that the outlet
of Loch Morar was at one time to the south-west, because the col
there does not rise more than 100 feet above the sea, and there is a
narrow belt of comparatively flat ground running southwards towards
the source of the burn called Allt Cam Carach. It will be observed,

196

BATHYMETRICAL SURVEY OF

by an examination of the depth map, that the deep water at the west
end of the loch runs in the direction of this flat ground. Some deep
borings along this flat ground might lead to interesting results.

Loch Morar (as well as Loch Beoraid) is a glen-lake which lies in a
transverse valley — that is to say, in a valley the direction of which
is independent of the geological structure of the region and crosses

English Miles
PIG. 32. INDEX MAP OF THE MORAR, SHIEL, AILORT, AND NAN UAMH BASINS.

irregularly the strike of the rocks. This fact very probably accounts
for the steep sides and the great depth to which the valley has been
scooped out. Should the country be depressed about 40 feet, Loch
Morar would be converted into a submerged valley and an arm of the
sea like Loch Etive. By some observers it is held that the great depth
of Loch Morar precludes the idea that it was scooped out by river-
action or by ice.

THE FRESH-WATER LOCHS OF SCOTLAND.

197

Loch Morar (see Plate XLIIL). — This is a large and beautiful loch,
lying amid wild and magnificent scenery on the west coast of Inverness-
shire, in the south-west portion of that county, immediately to the
south of Loch Nevis, which is a sea-loch running inland for 12 miles
from the Sound of Sleat. The west end of Loch Morar is about 3
miles from Arisaig, and 2J miles from Mallaig. Morar station, on
the Mallaig branch of the West Highland Railway, is within a few
hundred yards of the west end.

The loch is a little over 11J miles in length, and the maximum
breadth is over H miles near the west end; the mean breadth is

FIG. 33. LOCH MOEAR, LOOKING EAST FKOM THE WEST END.

(Photograph by Mr. T. N. Johnston, M.B., C.M., F.R.S.E.)

nearly T%- of a mile, or about 7^ per cent, of the length. The area
covered by the lake is 6596 acres, or nearly 10J square miles.

There are several islands, more or less richly covered with vegetation,
at the west end of the loch (see Fig. 33), and parts of the surrounding
land, especially on the north side, are fairly well wooded, all of which
greatly adds to the beauty and picturesqueness of the scenery at this
part, but as one proceeds eastwards towards the head of the loch the
scenery becomes wilder, the vegetation more scanty, and the mountains
on both sides of the loch rise higher and more steeply. At many
places on the north shore they rise precipitously from the water's edge,
and around the head of the loch they reach a height of fully 3000 feet.

198 BATHYMETRICAL SURVEY OF

Loch Morar is fed by numerous small burns and streams, the largest
feeder being the Meoble river, which, issuing from Loch Beoraid, falls
in, after a course of about 3 miles, at " Camas Luinge," a bay on the
south shore.

On the north shore, about 4J miles from the head of the loch, is a
large bay called " South Tarbet Bay," and here a narrow neck of land
about half a mile wide separates Loch Nevis from Loch Morar. A
track which runs up the north shore of Loch Morar to Tarbet on Loch
Nevis, crosses this neck of land by a narrow pass which rises to a height
of 200 feet. For a distance of about 6 miles from the west end, the
loch gradually narrows until a breadth of two-thirds of a mile is attained
a little to the east of Brinacory island on the north shore, then it
expands again to a breadth of over a mile opposite the entrance of the
Meoble river; gradually it narrows again until at its eastern end the
breadth is about one-third of a mile.

For a long time Loch Ness bore the reputation of being the deepest
loch in Scotland, but in the year 1879 Mr. J. Y. Buchanan, F.K.S.,
showed that Loch Morar contained depths of over 1000 feet, which
was deeper by several hundred feet than Loch Ness. In April, 1887,
Sir John Murray took a series of 18 soundings down the centre of the
loch, the greatest depth recorded being 1050 feet. In September of
the same year he again took 12 soundings at the deepest part of
the loch, the greatest depth obtained being 1026 feet. All these
soundings were taken by means of hempen-rope sounding-lines, as
well as those taken in 1892 by Dr. Thomas Scott, who recorded a
depth of 1020 feet. In June, 1896, Sir John Murray and the late Mr.
Fred. P. Pullar made a bathy metrical survey of the whole loch with
a wire-rope machine, but the chart they prepared was not published,
as it was found that the machine employed was untrustworthy. It was
therefore resolved to make a completely new survey. This was carried
out in June and July, 1902. Since that date the loch has been
frequently visited by members of the Lake Survey staff for the purpose
of taking temperatures and making biological observations.

The surface of the loch at the time the survey was made, in June,
1902, was 30-5 feet above sea-level, and in March, 1903, the level was
found to be 35 feet above the sea — a difference in level of 4J feet.
Altogether 1100 soundings were taken in the loch, or about 100
soundings to the square mile; the maximum depth recorded was 1017
feet. This is less than previous results, but is to be accounted for by
the use of wire rope, which nearly always gives a lesser depth than
the soundings with ordinary sounding-lines. The general results are
set forth on the accompanying map of the loch, with various cross-
sections.

Loch Morar is of simple conformation, the bottom falling on all sides
down to the deepest part, but with here and there a few minor undula-

THE FRESH-WATER LOCHS OF SCOTLAND. 199

tions of the lake-floor, especially in the wider western half of the loch,
where the contour-lines of depth are much more sinuous in character
than in the narrower eastern half. This is most noticeable in the
vicinity of the islands at the west end; the line of soundings running
south from Rudha Port na Coite shows several irregularities of the
lake-floor, and causes the 300-feet and 500-feet contours to twist in a
peculiar manner. Proceeding eastwards, the bottom undulates in such
a way as to cut up the 700-feet basin into three portions separated from
each other by shallower water, and towards the north shore, opposite
Camas na Togalach, a sounding of 367 feet is recorded separated from
the main basin by a shoaling of the bottom covered by 229 feet of water.
Farther east again, opposite Roinn a' Ghiubhais, the bottom shoals

PIG. 34. — DIAGRAMMATIC SECTION ACROSS LOCH MORAR AND THE HILLS ON BOTH
SIDES, SHOWING RELATION OP DEPTH TO HEIGHT. NATURAL SCALE.

slightly, so as to isolate a small area exceeding 900 feet in depth from
the main 900-feet basin. Opposite the entrance of the river Meoble, on
the southern shore, a sounding of 97 feet was recorded comparatively
near shore, which gives rise to a prolongation of the 100-feet contour-
line in that direction. Towards the east end of the loch, opposite Sron
an Drutain on the north shore, a rise of the bottom was observed
covered by 74 feet of water, surrounded by depths exceeding 100 feet.

The deepest part of the loch is at the wide portion opposite the
mouth of the Meoble river ; here, in the centre of the loch, the maximum
depth of 1017 feet was obtained, at a spot nearly midway between the
two ends of the loch. The area over 1000 feet in depth is not large,
extending only to a little over 4 acres. One sounding of 1002 feet was
obtained about 400 yards to the north-east of this area.

The area enclosed by the 900-feet contour extends to a length of
a little over 2 miles, with a maximum breadth of a quarter of a mile,
situated about 5J miles from the west end of the loch and 4 miles from
the east end. A small detached area over 900 feet in depth, with a
length of half a mile, lies about two-thirds of a mile to the west of
the main 900-feet basin.

The 800-feet contour encloses an area 4 miles in length with a
maximum breadth of about one-third of a mile. It extends from 4
miles from the west end of the loch to within 3 miles of the east end.

200

BATHYMETRICAL SURVEY OF

There are three depressions over 700 feet in depth. The main one
is nearly 5 miles in length, with a maximum breadth of two-fifths of a
mile, extending from nearly 4 miles from the west end of the loch to
within 2J miles of the east end. The other two depressions are small;
one lies about half a mile to the west of the main depression, and is
three-quarters of a mile in length; close to its western extremity lies
the third depression, which has a length of about one-third of a mile.

The 600-feet contour encloses an area which is 1\ miles in length,
extending from about 2 miles from the west end of the loch to 2 miles
from the east end.

FIG. 35. LOCH MORAR, LOOKING TOWARDS THE DEEPEST PART.

(Photograph by Mr. J. A. Harvie-Bmcn, F.Z.S.)

The 500-feet contour encloses an area extending to over 7^ miles in
length, reaching from If miles from the west end of the loch to about
2 miles from the east end.

The 400-feet contour encloses an area over 8| miles in length,
extending from 1J miles from the west end to 1 mile from the east end
of the loch.

The area over 300 feet in depth is 9J miles in length, extending
from nearly 1J miles from the west end to a little over half a mile from
the east end of the loch. There is a small detached area of over 300
feet in depth, about 5 acres in extent, near the north shore, a quarter
of a mile to the west of Brinacory island.

THE FRESH-WATER LOCHS OF SCOTLAND. 201

The area enclosed by the 200-feet contour is nearly 10J miles in
length, extending from about a mile from the west end to about one-
sixth of a mile from the east end of the loch.

The area enclosed by the 100-feet contour is over 11 miles in length,
extending from one-fifth of a mile from the west end of the loch to a
short distance from the east end.

The area covered by less than 100 feet of water is 2784 acres. The
areas between the consecutive contour-lines and the percentages to the
total area of the loch are as follows : —

0 to 100 feet 2784 acres 42 -2 per cent.

100,, 200 „ 863 „ 13-1

200,, 300 „ 528 „ 8'0

300,, 400 „ 488 „ 7'4

400,, 500 „ 331 „ 5-0

500 „ 600 „ 331 „ 5-0

600,, 700 „ 547 „ 8 -3

700,, 800 ,, 111 „ 1-7

800,, 900 ,, 530 „ 8-0

900 ,, 1000 ,, 79 „ 1-2

Over 1000 , 4 , O'l

6596 ,, 100-0

These contour-lines of depth approach each other very closely in
many places, showing that the slopes are very steep at these points. A
little to the west of the promontory called " Rudha nam Faiseachean ' '
on the south shore, south-east of the islands, this is very marked, the
slope being as much as 1 in 2J. Farther east on the south shore, off
"Eilean Allmhara," the slope is again very steep, as it also is off
Brinacory island, which lies almost opposite on the north shore.

As the surface of the loch is only 30 feet above sea-level, almost
the entire bed of the loch is below the level of the sea. The area
draining directly into Loch Morar is over 33,800 acres, or about 52
square miles.

The volume of water contained in the loch is estimated at
81,486,000,000 cubic feet, and the mean depth at 284 feet. Although
Loch Morar is the deepest loch, Loch Ness has a volume three times
as great, and its mean depth is 436 feet.

The deepest Scottish lochs next to Loch Morar are —

Loch Ness .. ... ... ... ... ... 751 feet.

,, Lomond .. 623 ,,

,. Lochy '... 531 „

,, Ericht 512 „

„ Tay 508 ,,

In the sea to the west of Morar there is no depth approaching 1000
feet, with the exception of a deep spot of 834 feet (139 fathoms) between

202

BATHYMETRICAL SURVEY OF

the islands of Rum and Skye, so that to get a depth of 1000 feet one
must go west of St. Kilda and Ireland, beyond the 100-fathoms line
in the Atlantic ocean. There are no depths comparable to this in the
North Sea, but the submarine valley known as the "Norwegian Gut,"
which runs round the west and south coast of Norway, is remarkably
deep, depths of 1794 feet (299 fathoms) and 1710 feet (285 fathoms)
having been obtained at the part called "The Sleeve."

There are seven lakes on the continent of Europe which exceed
Loch Morar in maximum depth, and in the following table their
maximum depths, heights of the water surface above sea-level, and
depths of their floors below sea-level, are shown as compared with
Loch Morar. The first four of these lakes are in Norway, the other
three are well-known Italian lakes.*

Name.

Max. depth.

Height above
sea-level.

Depth below
sea-level.

Hornisdalsvand

F.et.
1594-5

Feet.

167-3

F.et.

14272

Mjosen

1482-9

396-9

1086-0

Salsvatn. .

1460-0

42-6

1417-4

Tinnsjo

1437-0

606-9

830-1

Como

1341 -8

652-9

688-9

Maggiore

1220-4

472-4

748-0

Garda

1135-1

213-2

921 -9

Morar

1017'<»

30%")

986-5

'

The Lake of Geneva, in which very important and comprehensive
limnological work has been done by Prof. Forel, Dr. Ed. Sarasin, and
others, has a maximum depth of 1013-8 feet, and the height of the
water surface is 1220-4 feet above sea-level; the deepest part of the
lake-floor does not, therefore, go below sea-level, but lies at 206-6 feet
above it.

Temperature Observations. — A large number of observations on the
temperature of the water of Loch Morar has been made in various
seasons and in different years. On April 29 and September 3, 1887, Sir
John Murray took several series of temperatures, ranging from the
surface to the bottom. In the April observations the temperature
varied from 43°'9 at the surface to 42°-0 at the bottom, a range of
10<9, and in September the variation was from 57°-8 at the surface to
42°-l at the bottom, a range of 15°-7. On July 2 and 3, 1902, serial
temperatures were taken by the Lake Survey, and the variation was
from 55°-2 at the surface to 42°-2 at the bottom, a range of 13°-0.
Subsequently, on March 28, 1903, the temperature was found to be

* The figures referring to these continental lakes are derived from " Halbfass, Die
Morphoraetrie der Europaischen Seen," Zeltschr. Gesellsch. Erdk. Berlin, Jahrg. 1903,
p. 592; 1904, p. 204.

THE FRESH-WATER LOCHS OF SCOTLAND.

203

practically uniform from the surface to the bottom at a depth of 1010
feet, the surface temperature being 41°-9, while that at the bottom was
41°'8, a range of only 0°'l, and on October 23 of the same year the varia-
tion was from 500>2 at the surface to 43°-0 at the bottom in 1000 feet, a
range of 7°-2. The temperature at the depth of 1000 feet has generally
been regarded as fairly constant at about 42°-0 all the year round, with
a variation of about 00-2, and this higher record of 43°'0 may be due to
the increased amount of water draining into the loch during the wet
summer of 1903. The highest surface temperature recorded was one

FIG. 36. FALLS OF MORAR.

(Photograph by Mr. T. N. Johnston, M.B., C.M., F.R.S.E.)

of 59°-2 on June 30, 1902, off Bracora, the air temperature at the time
being 62°-8, with a moderate westerly breeze. This gives a total range
of 17°-4 between the highest surface and the lowest bottom temperature
recorded.

Deposits. — The deposits covering the floor of Loch Morar are mostly
dark brown in colour, which becomes almost black in the deeper parts.
A sample from 1000 feet was dark brown when wet, and greyish-black
when dry, containing about 50 per cent, of black vegetable matter,
about 10 per cent, of mineral particles (quartz, mica, hornblende, &c.),
with a mean diameter of 0-15 millimetre, and about 40 per cent, of
amorphous clayey matter, with many fine Diatoms and a few fragments

204

BATHYMETRICAL SURVEY OF

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THE FRESH-WATER LOCHS OF SCOTLAND.

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206 BATHYMETRICAL SURVEY OF

of arenaceous Foraminifera. The mica is present in extremely minute
flakes, and imperceptible to the naked eye in the unwashed material.
In this respect the material from Loch Morar differs from that obtained
in most of the other lochs, in the samples from which the glistening
mica flakes attract one's attention.

Loch Beoraid (see Plate XLIV.). — Loch Beoraid is a long narrow
loch, lying amidst wild and rocky scenery about 3 miles to the south of
Loch Morar. There were no Ordnance Survey bench-marks available
in the vicinity of the loch from which the level of the water surface
could be ascertained, but, from the position of the spot-levels, the height
was estimated at 168 feet above the sea. The loch trends in an east-to-
west direction, and is fed by numerous small burns, the largest, Allt a
Ghlinne Dhuinii, flowing in at the east end. The Meoble river, which
drains the loch, issues at the west end, and, after a course of 3 miles,
falls into Loch Morar. There are one or two small islands at the east
end of the loch, and one large one lying in the centre, almost equidistant
from both ends of the loch. The length of Loch Beoraid is 3J miles, and
its maximum breadth about one-third of a mile ; the mean breadth is
one-sixth of a mile, and the area covered by water is 352 acres, or over
half a square mile. The number of soundings taken was 120, the
maximum depth obtained being 159 feet; the mean depth is over 72
feet. The volume of water is estimated at 1,156,000,000 cubic feet,
and the drainage area extends to 7680 acres, or nearly 12 square miles.

There are two basins over 100 feet in depth ; one at the west end of
the loch three-quarters of a mile in length, with a maximum breadth of
one-sixth of a mile, approaching to within one-eighth of a mile from that
end. The maximum depth obtained in it was 147 feet, comparatively
very near the outflow. The eastern basin is nearly 1J miles in length,
with a maximum depth of 159 feet, the area over 150 feet in depth being
almost half a mile in length. The 50-feet area is continuous from end
to end, passing to the south of the large central island, the depth in the
channel being 53 feet. Loch Beoraid is a rock basin divided into two
separate basins by a rocky ridge which crosses the loch at the large
island. At the west end of the loch there is a rocky barrier, and the
river Meoble in its course forms a waterfall over rocks a short distance
from its exit. The loch was surveyed on July 1, 1902.

Temperature Observations. — The following series of temperatures
was taken about a quarter of a mile from the west end of the loch : —

Surface 60°'0 Fahr.

10 feet 59°-8 ,,

25 ,, 53°'9 ,,

50 „ 51°-0 „

100 , 47°'5 ,,

140 , 48° -0

THE FRESH- WATER LOCHS OF SCOTLAND. 207

These temperatures show a range of 12°*5 from the surface to 100
feet, with a small inversion of half a degree between 100 and 140 feet.
About 3 p.m. the surface temperature in the centre of the loch, half
a mile from the east end, with a strong westerly breeze blowing, was
found to be 61°-4.

Loch an Xostarie (see Plate XLV.). — Loch an Nostarie is a small
loch lying about a mile to the north of the west end of Loch Morar,
into which it drains through the little Loch a' Bhada Dharaich and
the Allt an Loin. It was surveyed on July 16, 1902, when, by
levelling from an Ordnance Survey bench-mark, the level of the water
surface was found to be 89-3 feet above sea-level. The loch has a length
of a little over half a mile, with a maximum breadth of nearly half a
mile, the mean breadth being a quarter of a mile. The area covered
by water extends to 90 acres, or nearly one-seventh of a square mile.
The number of soundings taken was 62, the maximum depth being 35
feet, while the mean depth is very nearly 11 feet. The volume of water
contained in the loch is estimated at 44,000,000 cubic feet, and the
drainage area extends to 1152 acres, or If square miles. The loch is
quite simple in conformation, the deep water occupying a central
position.

Temperature Observations. — On the date of the survey the tem-
perature of the water was found to be almost uniform from surface
to bottom, the difference between the surface temperature and that at
30 feet being only 00>1 Fahr., as shown by the following series taken at
4 p.m. in the deepest part of the loch : —

Surface 59° '3 Fahr.

10 feet 59°-3 „

20 „ 59°-2 ,,

30 „ 59°-2 „

The details regarding the lochs in the Morar basin are given in the
table on p. 208.

NOTES ON THE BIOLOGY OF LOCH MORAR.
By JAMES MURRAY.

Salmon, sea-trout, and loch-trout abound in Loch Morar, and the
sport is frequently very good, but the salmon as a rule are " dour "
to rise. Charr and the powan, or fresh-water herring (Cor eg onus), are
said to inhabit the loch.

The biology of Loch Morar offers several peculiarities as compared
with most of the other large Scottish lochs. The quantity of plankton

208

BATHYMETRICAL SURVEY OF

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THE FRESH- WATER LOCHS OF SCOTLAND. 209

is small, the larger Entomostraca especially being deficient. With this
is correlated an unusual clearness of the water (a white disc was visible
in June at a depth of 42 feet). The plankton hardly varies throughout
the year, except that Leptodora, Bythotrephes, Holopedium, and a few
other genera appear in the summer months only. The quantity was
slightly greater in March than at other seasons. At no season has
Daphnia been observed in the loch, and its absence has also been noted
by Dr. Thomas Scott (as long ago as 1892) and by Mr. D. J. Scourfield.
This is the more remarkable as Daphnia abounds in Loch an Nostarie,
about a mile distant, and discharging into Loch Morar by a con-
siderable stream. The only Diaptomus was the common D. gracilis ;
while many of the other large lochs in about the same latitude have also
one or other of that group of closely related species represented in
Loch Ness by D. laticeps. The Bosmina was the typical B. longispinay
and not B. obtusirostris, which is the common species in the majority
of the Scottish lochs. In contradistinction to the scarcity of larger
organisms, many very small species were abundant. Desmids especially,
of a few species, were unusually numerous in the plankton at all seasons.
A remarkable variety of Xanthidium subhastiferum has been described
by Messrs. West from material collected by the Lake Survey. In this
the two spines of each side of the semi-cell, instead of lying in the same
plane as the semi-cell, are placed side by side on the external angles of
the wedge-shaped semi-cell.

The aquatic plants, growing in the shallow water among the islands,
yielded an abundant fauna of microscopic animals, especially of Rotifera
and Tardigrada. From among these there have been described two
new species of Bdelloid Rotifers. A new water-bear of the genus
Echiniscus has also been described. It is distinguished chiefly by having
the dorsal plates covered by a large hexagonal reticulation in addition
to the usual dots. This species was very numerous in October, and has
not yet been met with elsewhere.

210 BATHYMETRICAL SURVEY OF

LOCHS OF THE EWE BASIN.

THIRTEEN lochs draining into Loch Ewe were visited by the Lake
Survey, viz., Loch Maree, Lochan Fada, Lochs Garbhaig, Coulin,
Glair, Tollie, Kernsary, Ghiuragarstidh, Mhic' Ille Riabhaich, a'
Bhaid-Luachraich, Sguod, an t-Slagain, and an Drainc. The two
last-mentioned lochs fall into the sea just outside the entrance to Loch
Ewe, but it has been found convenient to include them with the lochs
of the Ewe basin. The relations between the various lochs will be
readily grasped by reference to the small index map of the district
shown in Fig. 37. The drainage area under consideration extends
from the mouth of Loch Ewe to the summit of Cam Odhar in the
south, and close to the shores of Loch Fannich in the east, and is about
30 miles in length from north to south, and about 17 miles in maximum
width from east to west. The total area is about 220 square miles
(excluding Loch Ewe), and, as will be seen from the table at the end
of this paper, about 185J square miles drain into the lochs now to be
dealt with, leaving about 35 square miles draining into the sea irrespec-
tive of these lochs. The head- waters of the basin on the south take
their rise on the flanks of Beinn Liath Mhor and Carn Breac, flowing
by the river Coulin into Loch Coulin, thence into Loch Clair, thence
by the Allt Ghairbhe into the Kinlochewe river, at Kinlochewe, which
falls into Loch Maree at its head. A short distance along the north-
eastern shore Loch Maree receives the outflow from Lochan Fada by
the Abhuinn an Fhasaigh, and, still further down, the outflow from
Loch Garbhaig* by the Amhainn na Fuirneis. At its foot Loch Maree
receives the outflow from Loch Tollie on the west, and from Lochs
Ghiuragarstidh and Kernsary on the north-east, and its waters are
carried by the river Ewe into the head of Loch Ewe. The outflow
from Loch Sguod falls into Loch Ewe on its western shore, and the
outflow from Lochs Mhic' Ille Riabhaich and a' Bhaid-Luachraich
on its eastern shore. Loch an t-Slagain flows into Slaggan bay at the
entrance to Loch Ewe, and Loch an Drainc flows into The Minch a
short distance to the west of the entrance to Loch Ewe. A number of
small lochs within the district now being dealt with could not be
surveyed for lack of boats.

* The smaller Loch Garbhaig lying to the west of Loch Maree was not sounded.

THE FRESH- WATER LOCHS OF SCOTLAND. 211

The geology of this district is described by Drs. Peach and Home,
their important contribution being illustrated by a special geological
map.

Loch Maree (see Plates XLVI. and XLVII.).— The loch derives its
name from Saint Maelrubha, who in 671 A.D. left Bangor, and after
founding one church at Applecross, founded another on Isle Maree.
It is the largest sheet of fresh water in Scotland north of Loch Ness,
and trends in a north-west and south-east direction.

On the north-east side of the loch, and parallel to it, runs a grand
series of mountains — Beinn Airidh Charr, Meall Mheannidh, Beinn
Lair, Slioch, Sgurr an Tuill Bhain, and Beinn a Mhuinidh ; the slope
for the first 1000 feet all along this north-eastern shore is very steep, in
many places exceeding 45°. To the south-west rise Beinn Eighe, Beinn
a Chearcaill, and Beinn an Eoin ; the sharp ridge of the former, com-
posed of white quartzite, forms an especially fine object from the loch to
the north of the Gruididh. But the two most striking features of Loch
Maree are Slioch and Isle Maree; the huge sugar-loaf form of Slioch
is conspicuous from almost every part of the loch, and, though one of
the smaller islands, Isle Maree, owing to the large number of trees
growing upon it, stands out against the dark background of the heather-
covered islands and the cliffs of the north-eastern shore.

The great feature 'of Loch Maree is the large number and great
area of its islands. Prof. Penck, in his work on the Lake of Constance,
lays great stress on the ' ' insulosity, " i.e., "the proportion of the area
of the islands to that of the water surface ; " this in Loch Maree is 0'09,
or three times as great as that of the Lake of Cheim (0'03), and nine
times as great as that of the Lake of Constance (0-01). Its insulosity is
also greater than that of any other large lake in Great Britain, that of
Loch Lomond being 0'08, though it is surpassed in this respect by one
of the small lochs in the Assynt district (Loch Crocach, whose insulosity
is 0-091).

Many of the islands were joined together when the Lake Survey
visited the loch, owing to the low level of the water. A few small
rocks and reefs occur out in the channel to the north of the main
group of islands and removed some considerable distance from the rest.
Large numbers of the Lesser Black-Backed Gull (Larus fuscus) breed
on the larger islands, and two pairs and young of the Greater Black-
Backed Gull (Larus marinus) were observed on two of the smaller islets.
Isle Maree, Eilean Ghruididh, Eilean Subhainn, and Eilean Ruairid
Bheag have been used at one time as fortresses or habitations.

The level of Loch Maree was found by the Ordnance Surveyors to
be 32-1 feet above sea-level on September 15, 1870; on July 16, 1902,
the surface of the water was 29-5 feet above sea-level. The loch was
surveyed on July 16 to 24, 1902, and the water remained at very nearly

212

BATHYMETRICAL SURVEY OF

the same level during the nine days spent in surveying it. The average
height of the water for the whole of the year is about 1 J feet above the
level on July 16, 1902 ; the water has been known to rise 9 feet higher
and to fall 1 foot lower than the level on this date.

Bartholomew

9 ! ? * « *

FIG. 37. INDEX MAP OF THE EWE BASIN.

^Eng Miles

Before dealing with the statistics of Loch Maree, it is necessary to
state that there has been included in the loch a large portion of the
piece of water styled " River Ewe;" soundings were taken in the
so-called river, and depths of over 30 feet were obtained in places down
to beyond the commencement of the Pool Crofts. Just above the partly

THE FRESH- WATER LOCHS OF SCOTLAND. 213

artificial dam depths of 37 and 35 feet were obtained, and these would
seem to point to the fact that down to here the " river " is nothing
more than an arm of the loch, with a current flowing along it to the
outfall. That this place is the beginning of the river was evidently
the opinion in past time, for it was here that the old iron-workers
built their dam to obtain water for working "A Cheardach Ruardh"
(The Red Smiddy).

The length of the loch as thus defined is 13 J miles, and the
maximum breadth rather over 2 miles. The mean breadth is nine-
tenths of a mile, being 7 per cent, of the length. Its waters cover an
area of over 11 square miles, and the islands nearly 1 square mile.
Loch Maree has a large shore development, i.e., the length of the
shore-line is much greater than the circumference of a circle whose
area is equal to that of the loch. The shore development is 3'15, being
greater than that of any other large loch in Scotland. The drainage
area is 171 square miles, or 15 times the area of the loch.

Twelve hundred soundings were taken in Loch Maree, and the
greatest depth obtained was 367 feet, in the middle of the loch to the
south-west of Rudh' a' Ghuibhais ; the bottom of the loch here is thus
337J feet below sea-level. The volume of water is estimated at over
38,500 millions of cubic feet, and the mean depth at 125 feet (34 per
cent, of the maximum depth). The breadth of the loch at the position
of the deepest sounding is seven times the depth.

Loch Maree is divided into three main basins — (1) that extending
from Isle Maree to the south-east end of the loch, which may be called
the " Ghruididh basin;" (2) that lying to the south of the islands,
which may be called the ' ' Slattadale basin ; ' ' and (3) that extending
from the north-east of Eilean Ruairid Mor to the north-west end of the
loch, which may be called the "Ardlair basin. "

(1) The Ghruididh basin. — This basin is the largest and deepest of
the three. The 200-feet area extends from a quarter of a mile to the
east of Isle Maree to about half a mile from the south-east end of the
loch, and has a length of 6J miles, its average width being about three-
quarters of a mile. The main 300-feet basin has a length of 2 miles
and a mean breadth of about a quarter of a mile ; it extends from south
of Coppachy to north of milestone 3 miles from Kinlochewe. There is
another smaller 300-feet area a little to the north-west of the main
area. The 350-feet basin has a length of one mile and an average
width of one-sixth of a mile ; it extends from north of milestone 5 miles
from Kinlochewe to north of milestone 4 miles from Kinlochewe.

The greatest depth is 367 feet, this depth being obtained in the
middle of the loch to the south of Rudh' a' Ghuibhais. The deepest
part of the loch thus lies between the two faults shown on the Geological
Map, one of which cuts the loch a little to the south-east of the river
Ghruididh on the south-west shore, and the other where the stream from

214

BATHYMETRICAL SURVEY OF

Lochan Fada enters the loch on the north-east shore. The deepest part
of this whole basin occurs where the great mass of Slioch on the one
side, and the heights of the Kinlochewe forest on the other, rise steeply
up from the shore, and, as it were, compress the valley into its narrowest
limits.

This basin has a typical " cauldron " shape, which is brought out
in the section on the map, the slope on both sides down to the 350-
feet contour-line being one of 26J°; the flat portion in the middle is
about 300 yards broad at the deepest place. The slope up to the 1000-
feet contour-line is one of 24J° on the north-east shore, and one of 14°
on the south-west shore.

FIG. 38. LOCH MAREE, THE ISLANDS IN THE MIDDLE DISTANCE.

(Photograph by Mr. J. A. Harvie-Brown, F.Z.S.)

It should be noted that the floor of the loch rises steeply where the
second fault alluded to cuts it, that part of the loch lying to the south-
east of this fault being very shallow. This feature is also seen where
the same fault cuts the east end of Lochan Fada.

In Loch Maree a large number of the streams have formed very
decided alluvial cones; e.g. the large one at the mouth of the Ghruididh
river. This feature is much more marked in Loch Maree than in the
majority of lochs. Other features of interest in this basin are the
comparatively deep soundings in Ob nam Muc and the inlet to the
south-east of this; and the curious hill on the bottom of the loch to
the south of Letterewe (300 yards from the shore), the summit of which
is covered by 44 feet of water.

THE FRESH- WATER LOCHS OF SCOTLAND. 215

(2) The Slattadale basiu. — This basin extends from west of Eilean
Ruairid Mor to south of Eilean Subhainn. The 150-feet area has a
length of 2 miles and a mean breadth of a quarter of a mile. The curve
traced out by this contour to the east of the Slattadale river is very
remarkable ; the extension of the shallower part of the loch into the
150-feet area is in the direction of the Slattadale river, but the sound-
ings nearer to the shore give no indication that this bank is due to the
material brought down by the river. The 200-feet area extends from
south of Eilean Ruairid Mor to north of Stalla nam Manach, its length
being nearly 1| miles, and its average breadth about 150 yards. The
greatest depth is 232 feet in the extreme north-west of the basin. In
a line with the curious indentation in the 150-feet contour-line the
200-feet basin is very narrow and shallow (202 feet).

Comparatively deep soundings were obtained in all the channels
extending into the islands, and it is noteworthy that the long and
narrow passage between Eilean Subhainn and Garbh Eilean lies in
a line with the narrow prolongation of deeper water from Rudha
Chailleach into the shallow water north of the islands.

Ob na h-Innse Moire in Eilean Subhainn was cut off from the main
part of the loch by a sand-bar. This was also the case with the inlet to
the north-west of Ob na h-Innse Moire, but this inlet had its surface
covered with weeds and boulders.

(3) The Ardlair basin. — The outline of this basin is also very
irregular, and the bottom more so than in either of the other basins.
The 100-feet area has a length of 3J miles and a mean breadth of
three-quarters of a mile. The 200-feet area has a length of 2^ miles and
an average breadth of one-third of a mile. The length of the 250-feet
basin is two-thirds of a mile and the average breadth a quarter of a
mile. The greatest depth in this basin is 285 feet, occurring about
700 yards to the south-east of Rudh' Aird an Anail.

In this basin the contour-lines run very close to the north-eastern
shore in the western and central parts of the basin, but spread out
towards the eastern part. Again, they run very close to the shore
round the western coast of Eilean Ruairid Mor and round Rudh' Aird
an Anail. They have a very sinuous outline in the eastern part of the
basin.

As stated above, the floor of this basin is very irregular; several
small hills rise above the general level of the bottom, as that to the
south of Ardlair and that to the east of Rudh' Aird an Anail. The
north-western extension of this basin, called " River Ewe," has
already been noticed.

There remain for consideration the ridges between the basins and
the large tract of shallow water to the north of the islands. The
ridge which runs across from Eilean Ruairid Mor to the mouth of
Allt na Doire is very marked. The lowest part of the ridge is 83 feet

216 BATHYMETRICAL SURVEY OF

below the surface of Loch Maree, whilst the distance between the two
100-feet contour-lines at this place is 120 yards, and that between the
two 150-feet contours is 550 yards.

The shallow water to the north of the islands is much more remark-
able. A large part of this area is under 50 feet in depth, and the
deepest water that occurs anywhere between Creag Tharbh and Rudha
Chailleach is 79 feet, though it is along this northern channel that the
great fault must run. Right in the middle of the channel, underneath
Creag Tarbh, the water is only 41 feet in depth ; the hills on the north
shore rise steeply up to heights of over 2000 feet in places, and the
slope up to the 1000-feet contour-line is at an angle of 45° ; hence the
difference between the sub-aerial and the sub-aqueous slopes is in this
place very marked. Rudha Chailleach (the witch's point) is a narrow
spit of shingle stretching out to a considerable distance into the loch,
with deep water close to the shore. From this point a narrow channel
of deeper water projects right across the loch towards the opening
between Eilean Subhainn and Garbh Eilean.

The ridge between the Slattadale and Ghruididh basins is merely a
continuation of the islands. The depths on it are much less than on
either of the other ridges; there is, however, a fairly deep channel,
through which the steamer passes, ranging in depth from 62 feet to
28 feet; this channel is narrowest and shallowest between Isle Maree
and Eilean Eachainn. To the south of Isle Maree is a large sand-flat,
which in July, 1902, was covered by less than a foot of water, and on
which were many boulders rising above the surface of the water.

The areas between the consecutive contour-lines, and the per-
centages to the total area of the loch, are as follows : —

0 to 50 feet 2090 acres 29 '6 per cent.

50,, 100 , 1283 „ 18-2

100,, 150

150 „ 200

200 „ 250

250,, 300

300,, 350

Over 350

1066 „ 15-1

877 „ 12-4

977 „ 13-9

412 „ 5-8

254 „ 3-6

99 , 1-4

7058 „ 100-0

It will be observed that the zone between 200 and 250 feet is larger
than that between 150 and 200 feet, otherwise the areas between the
contour-lines drawn in at equal intervals decrease gradually with
increase of depth.

The Small Loch on Eilean Subhainn. — Apparently this loch has not
been considered important enough to receive a name, but the fact that
it had the appearance of being of some depth, whereas the other lochs
on the islands on Loch Maree are overgrown with weeds or moss,

THE FRESH- WATER LOCHS OF SCOTLAND. 217

induced the Lake Survey to sound it. The trouble taken was well
repaid by the curious nature of the bottom revealed by the soundings.*

Eilean Subhainn is 292J acres in area, its shore-line being very
irregular. The surface of the ground is uneven, though nowhere except
in the south-east corner is it very elevated ; here, however, a small hill
rises to a height of 84 feet above the level of Loch Maree. The greater
part of the island is not more than 30 to 40 feet above Loch Maree,
this rise for the most part taking place in the first 30 yards, and in
some places there are vertical cliffs from 20 to 30 feet in height. In
these cliffs it is seen that the island is composed of Torridon Sandstone ;
the rock does not appear elsewhere except around the little loch, the
island being covered with peat, with a considerable number of fir trees
round the shore and in the south-east corner.

The loch lies in a small hollow in the centre of the island, being
situated about a quarter of a mile from the south-east shore, and one-
third of a mile from the west shore of the island, and about 150 yards
from the Lily Loch. Its level was determined on July 24, 1902, to
be 57*4 feet above sea-level, and 27'9 feet above the surface of Loch
Maree.

The loch trends in an east and west direction, and its length is a
little over 250 yards ; its maximum breadth is about 100 yards, and the
mean breadth about 70 yards. Its waters cover an area of nearly 5
acres, and its drainage area is ten times greater, or 51 acres; the shore
development is 1-62 and the insulosity 0-02. The maximum depth is
64 feet, and hence the bottom of the loch is 30 feet below the level
of Loch Maree, and 6J feet below sea-level. The volume of water
contained in the loch is estimated at 6 millions of cubic feet, and the
mean depth at 46^ feet.

The loch is fairly regular in outline, and has three small islands in
it. The deepest part is a mere hole near the western end ; on the ridge
running across from the island near the north shore to the island with
the tree there is only 5 feet of water, but there is a considerable depth
of mud. In the eastern part of the loch depths of 12 feet were met
with. Eighty -five per cent, of the total area of the loch is less than
50 feet in depth. This loch is the only one situated on an island in
another loch which has been visited by the Lake Survey. It was
surveyed on July 24, 1902.

Temperature Observations. — Many surface temperatures were taken
in Loch Maree between July 16 and 24, 1902, the greatest range
observed being from 53°-3 off Letterewe at 11 a.m. on the 21st, to 57°-0
at Talladale at 7 p.m. on the 22nd. The surface temperature in the
south-east end of the loch was almost always higher than that in the

* The method of sounding out this loch is interesting: it was found impossible to
transport a boat to the loch, and Mr. Garrett took soundings by hand while swimming.

218

BATHYMETRICAL SURVEY OF

north-west end, owing to the north-west winds prevailing during the
time the Lake Survey was on the loch. For instance, on July 19 the
temperature of the surface north-west of Rudh' Aird an Anail was
53°-9 at 3 p.m., and off Ardlair it was 54°-0 at 4 p.m., whilst at
3.15 p.m. it was 55°*3 to the south-east of Fhasaigh.

Five serial observations were taken on July 19 and 21, as given in
the following table : —

Depth
in

feet.

Loch Maree, oppo-
site Pool Crofts,
July 19, 1902,
12 noon. No
wind.

Loch Maree, S.W.
of E. Ruairid
M6r, July 19,
1902, 6 p.m.
Stiff N. breeze.

Loch Maree, oppo-
site Letterewe,
July 21, 1902,
12.45 p.m.

Loch Maree. N. of
E. Ruairid M6r,
July 21, 1902,
1 p.m. Light
N.W. breeze.

Loch Maree, off
Rudh' a' Ghui-
bhais, July 21,
1902. 6 p.m.
Moderate N.W.
wind.

0

o
53-5

o

54'7

53-9

53-9

53°-9

0

54-5

5

53-8

...

54-2

7

...

...

10

...

...

53:6

53 :7

53-7

54-2

15

53-6

54-7

53'5

53-3

53-4

20

...

53-5

54-2

25

54-0

53-5

53 :7

...

30

53-6

53-3

V

54-0

35

...

53-2

...

50

53:0

53-1

53-0

54 :0

75

50-0

50-8

50-3

53-6

80

...

...

...

...

85

49-6

100

48 '-0

49-0

48"2

48-0

150

48-1

46-9

46-6

46-4

200

...

47-0

45-9

46-0

45-9

250

...

45-4

300

...

45-6

350

...

...

...

...

45-5

Below the surface the fall in temperature was slow down to about
50 feet, when the fall became very rapid down to 150 feet, and then
slow again to the bottom. Though these are the characteristics of the
three series taken on the 21st, that taken on the 19th to the south of
Eilean Ruairid Mor in the Slattadale basin does not agree with the
others. In this case there was a rapid fall from 20 to 100 feet, and
then a slight rise in temperature to 150 feet, and then a slow fall again
to 200 feet.

The series taken to the north of Eilean Ruairid Mor on the 21st is
interesting on account of the decided inversion at 25 feet. Though
these inversions of temperature have occasionally been observed, they
are by no means common. In this case it was noticed that the tempera-
ture fell from 53°'9 at the surface to 53°'7 at 10 feet, and to 53°'3 at 15
feet, and then rose to 53°'5 at 25 feet, and then fell again steadily below
this depth. The series down to 25 feet was repeated with the results
shown in the second column under this head, which proved that the
inversion, though small, was real and not due to the instrument.

THE FRESH-WATER LOCHS OF SCOTLAND.

219

Lochan Fada (see Plate XLVIIL). — Lochan Fada (i.e., the long
loch) is the largest of its name. It is situated about 3 miles to the
north-east of the upper end of Loch Maree, and runs parallel to it for
a distance of 4 miles. The scenery around Lochan Fada is of the most
magnificent description, Slioch and Beinn Lair overlooking it on the
south-west shore, and Beinn Tharsuinn and A Mhaighdean on the north-
east shore. The ridge between Lochan Fada and Gorm Loch Mor is
particularly noticeable ; the rise from the loch is 750 feet in 350 yards,
and the top of the ridge is exactly like a knife-edge. The crags on the

FIG. 39. LOCH FADA, LOOKING NORTH, SHOWING RIDGE.

(Photograph by Mr. T. N. Johnston, M.B., C.M., F.R.S.E.)

south-west shore are very bold and wild, being composed of the Beinn
Lair sill of hornblende-schist, and extend from between Lochan Fada
and Loch Garbhaig to south of Loch Fionn. When standing above the
north-west end of the loch, the outlet to the south is not suspected;
the loch appears to drain away down the continuation of the glen into
Glen Na Muic. Doubtless at one time this was the outlet of the loch,
for the col here between Lochan Sgeireach and L'och Gleann na Muic
is only 13 feet above the level of Lochan Fada. But Abhuinn an
Fhasaigh, having a much shorter course than Abhuinn Gleann na Muic,
has been able to cut back much more rapidly, and perhaps all the
more so since its course lies along the line of fault, which runs from

220 BATHYMETRICAL SURVEY OF

Loch Meallan an Fhudair to Loch Maree, and has tapped Lochan Fada,
slightly lowering its level, thus beheading Abhuinn Gleann na Muic.

The height of the loch above sea-level was not determined by the
Ordnance Survey, nor by the Lake Survey when sounded on July 25
to 28, 1902, owing to absence of bench-marks, but, judging from the
spot-levels and the 1000-feet contour-line, its level must be about 1005
or 1006 feet above the sea.

The length of Lochan Fada is 3| miles, and its maximum breadth
nearly two-thirds of a mile; the mean breadth is over one-third of a
mile. Its waters cover an area of nearly 1J square miles, and it drains
an area 6J times greater, or over 9J square miles. The maximum
depth is 248 feet ; this occurs in the centre of the loch off the mouth of
Allt Meallan a' Chruidh. The mean depth is estimated at 102 feet, and
the volume at 4091 millions of cubic feet. The breadth of the loch at
the position of the deepest sounding is twelve times the depth. The
shore development is 2-16, and the insulosity is nil ; Lochan Fada, like
so many of the larger lochs, has not a single island.

The bottom of Lochan Fada is very regular, the 50-feet and 100-feet
areas being continuous, and extending almost from one end of the loch
to the other. The main 150-feet area extends from west of Claona to
the narrower part of the loch, and has a length of 1J miles; there is t*
small 150-feet area near the south-east end of the loch. The 200-feet
area extends from south-west of Claona to west of Allt na Botaig ; its
length is one mile, and average width 280 yards.

The areas between the consecutive contour-lines, and the per-
centages to the total area of the loch, are as follows : —

Oto 60 feet 230 acres 25 -0 per cent.

50,, 100 ,, 236 „ 25-7

100,, 150 „ 263 „ 28-7

150,, 200 „ 100 „ 10-8

Over 200 , 90 , 9 '8

919 , 100-0

It is unusual to observe, on proceeding from the shore into deeper
water, an increasing area between the contour-lines drawn at regular
intervals, as in the case of Lochan Fada, and indicates an average steep
slope near shore. A glance at the map shows that the 50-feet contour
follows closely the outline of the loch, and in places approaches very
close to the shore.

Seiche. — On July 28, beginning at 1 p.m., a well-marked seiche was
observed in Lochan Fada in a sheltered bay at the south-west end of
the loch ; the wind was strong from the west. The amplitude was half
an inch, and the period about 11-6 minutes; but this oscillation was so
broken up by two other oscillations, whose periods were about 2J

THE FRESH- WATER LOCHS OF SCOTLAND. 221

minutes and 1 minute respectively, that the whole effect was extremely
complicated, and no calculations could be made from the observations.
Temperature Observations. — The temperatures taken in Lochan Fada
are extremely interesting, because they indicate a much lower tempe-
rature than was observed in any of the other lochs in the district at the
same time of the year, as shown by the following series taken at 6.40
p.m. on July 28, 1902, to the south of Allt Meallan a' Chruidh : —

Surface 51°'l Fahr.

10 feet 51°'l „

20 „ ... 51°'l „

50 „ 51°-0 „

75 „ 45°-8 „

100 „ 45°-0 „

150 „ 44°-3 „

220 „ 44°-l „

This series indicates an almost constant temperature down to 50
feet, then a fall of 5°-2 between 50 and 75 feet (a fall exceeding 1°-0 per
5 feet of depth), and then a slight decrease of l°-7 down to the bottom in
220 feet. Compared with the larger and deeper Loch Maree, the water
in Lochan Fada was found to be colder at all depths than that in Loch
Maree : thus the surface of Lochan Fada had a temperature about 3|°
lower than was observed in the surface waters of Loch Maree a week
earlier, and at the bottom of Lochan Fada, in 220 feet, the temperature
was found to be about 1J° lower than at the bottom of Loch Maree in
350 feet. This is probably due to the fact that Lochan Fada is very
deep, considering its area, and therefore a large volume of water has to
be warmed, while only a comparatively limited area is exposed to the
heating agencies.

Loch Garbhaig (see Plate XLVL). — Loch Garbhaig lies between
Lochan Fada and Loch Maree, about half a mile from the former and
1^ miles from the latter. It drains into Loch Maree by the Amhainn
na Fuirneis, which leaves the loch at its western end, and, flowing in a
westerly direction, enters Loch Maree between Furness and Letterewe.
The ground at the eastern end is not much elevated above the surface of
the loch, the col leading over to Lochan Fada, but on the south side
Slioch rises up from the shore to a height of 3200 feet, and on the north
side the high ground to the east of Beinn Lair rises to over 2500 feet.
The most noticeable feature of the surrounding country is its bareness.
The height of the loch above the sea was not determined by levelling
when surveyed on July 25, 1902, but from the contour-lines the level
is probably between 1005 and 1015 feet.

Loch Garbhaig is over a mile in length, with a maximum breadth
of nearly one-third of a mile, the mean breadth being one-fifth of a
mile. Its waters cover an area of about 148 acres, and it drains an

222 BATHYMETRICAL SURVEY OF

area 10J times greater, or nearly 2£ square miles. The maximum
depth of 93 feet was observed about 300 yards from the eastern shore.
The volume of water contained in the loch is estimateU at 228 millions
of cubic feet, and the mean depth at 35| feet. The breadth of the
loch at the position of the deepest sounding is sixteen times the depth.
The shore development is 2*15, and the insulosity 0*014.

The 25-feet area is continuous, passing to the north of the large
island. The 50- and 75-feet areas lie in the eastern part of the loch,
though there is one sounding of 50 feet in the extreme west. The
50-feet area has a length of nearly half a mile, and extends to within
40 yards of the eastern shore, while the 75-feet area is a quarter of
a mile in length. The areas between the consecutive contour-lines,
and the percentages to the total area of the loch, are as follows : —

0 to 25 feet 67 acres 45 '4 per cent.

25,, 50 „ 42 „ 28-3

50 „ 75 „ 20 „ 13-3

Over 75 , 19 , 12'5

148 , 100-0

The temperature of the surface water in Loch Garbhaig at 4 p.m.
on July 25, 1902, was 540>9 Fahr., or nearly 4° warmer than that
observed in Lochan Fada, which lies at the same elevation; no serial
temperatures were taken.

Loch Glair (see Plate XLIX.). — Loch Clair is situated about three
miles to the south-west of Kinlochewe, at the head of Loch Maree. The
ground to the north and west rises to the heights of Beinn Eighe and
Sgurr Dubh, the lower ground being covered by moraines. It was
surveyed on July 24, 1902, and the elevation of the water surface above
the sea was determined by levelling from bench-mark as being 303' 1
feet.

Loch Clair is over 1J miles in length, with a maximum breadth of
about 600 yards, the mean breadth being about 300 yards. Its waters
cover an area of about 160 acres (a quarter of a square mile), and it
drains directly an area of 6J square miles, but since it receives the
outflow from Loch Coulin its total drainage area is 20J square miles
— an area 83 times greater than that of the loch. The maximum
depth is identical with that observed in Loch Garbhaig, viz., 93 feet,
and occurs about 150 yards from the eastern shore off Creag naRianaich.
The volume is estimated at 287 millions of cubic feet, and the mean
depth at 42 feet. The breadth of the loch at the position of the deepest
sounding is sixteen times the depth. The shore development is 2*01,
and the insulosity very small (O'OOl), there being only two small
islands in the loch.

THE FRESH-WATER LOCHS OF SCOTLAND. 223

The bottom of Loch Clair is fairly regular, the deeper water being
found in the wide south-eastern portion, where there is a 50-feet basin
about half a mile in length, enclosing a 75-feet basin one-third of a
mile in length. The 25-feet area is continuous, passing to the south
of the larger island, between which and the southern shore a depth of
46 feet was found. The areas between the consecutive contour-lines,
and the percentages to the total area of the loch, are as follows: —

0 to 25 feet 58 acres 34 -9 per cent.

•-'"> „ 50 „ 38 „ 24-4

50,, 75 „ 41 „ 25-9

Over 75 , 23 , 14'8

160 „ 100-0

It will be observed that the zone between 25 and 50 feet is smaller
than the zone between 50 and 75 feet, indicating that the average
slope is steeper in the shallower zone.

Temperature Observations. — A series of temperatures taken at 4 p.m.
on July 24, 1902, in the deep water gave the following results : —

Surface ... 570<OFahr.

5 feet 57°'7 „

10 ,, ... 57°'2 „

•20 ,, 57°'2 ,,

30 , 54°0 „

40 „ 49°'9 „

50 „ 48°'7 „

85 „ 48°-0 „

It will be noticed that the temperature of the water between
5 and 20 feet was higher than that at the surface, the highest reading
being at 5 feet. Between 20 and 30 feet a fall of 3°'2 is recorded, and
between 30 and 40 feet a fall of 4°-l, a total fall of 7°'3 in 20 feet, the
extreme range shown by the observations being 9°-7.

Loch Coulin (see Plate XLIX.). — Loch Coulin is situated 300 yards
to the south-east of Loch Clair, into which it drains. Doubtless, in very
recent times, they formed one loch, for the ground between them is low
and alluvial. To the south-west and south-east rise Beinn Liath Mor
and Carn Breac. Loch Couliu is very much overgrown with weeds,
especially in the narrow north-western portion. It was surveyed on
July 24, 1902, the water surface being 304-6 feet above sea-level, or
H feet above the level of Loch Clair.

Loch Coulin is 1J miles in length, with a maximum breadth of one-
third of a mile, the mean breadth being about 250 yards. Its waters
cover an area of 113 acres, and it drains an area 78 times greater, or
14 square miles. The maximum depth of 49 feet occurs near the
centre of the broader south-eastern portion of the loch. The volume

224

BATHYMETRICAL SURVEY OF

of water is estimated at 90 million cubic feet, and the mean depth
at 18£ feet. The breadth of the loch at the position of the deepest
sounding is 31 times the depth. The shore development is 2-45, and
the insulosity nil.

Loch Coulin is very irregular in outline, and is cut up into three
basins, the north-western basin having a maximum depth of 32 feet,
and the central basin a maximum of 22 feet. The main basin is
confined to the broad south-eastern part of the loch, and the contour-
lines approach very close to the eastern shore, off which the slope is
steep. There are two isolated soundings less than 25 feet within this
area, and deep water is found at the entrance of the river Coulin.

FIG. 40. LOCH COULIN, LOOKING NORTH.

(Photograph by Mr. T. N. Johnston, M.B., C.M., F.R.S.E.)

The area covered by less than 25 feet of water is over 80 acres, or 72
per cent, of the entire area of the loch.

Temperature Observations. — A series of temperatures was taken in
the deep part of the loch at 5 p.m. on July 24, 1902, with the following
results : —

Surface
5 feet
10 „
15 „
'20 „
30 „
40 ,

57°'OFahr.

57° -0 „

57°'l „

57° -0 „

55° -5 „

54°'8 „
53° -0

THE FRESH- WATER LOCHS OF SCOTLAND. 225

The temperature was found to be constant from the surface to a
depth of 15 feet, thence the temperature fell 4° to the bottom in 40
feet.

Loch Tollie (see Plate XLVII.).— Loch Tollie is situated 1J miles to
the west of the lower end of Loch Maree, and drains into its north-
western arm. The ground immediately surrounding the loch is low,
though Meall Airidh Mhic Criadh to the south-west, and Creag Mhor
Thollie to the south-east, rise to over 1100 feet. The loch is roughly
elliptical in outline, the major axis having an east and west direction.
One of the islands near the northern shore was for some time a strong-
hold of the McLeods.

Loch Tollie was surveyed on July 29, 1902, the elevation of the lake-
surface being 387-0 feet above sea-level ; when visited by the Ordnance
Survey officers on November 13, 1869, the level was found to be 387-7
feet. The water must at one time have stood at a higher level, for at
the east end, where the stream leaves the loch, there are the remains of
a dam (now fast disappearing), which held up the water for supplying
a mill farther down the burn.

Loch Tollie is under a mile in length, with a maximum breadth of
about 800 yards, the mean breadth being about 500 yards. Its waters
cover an area of about 169 acres (a quarter of a square mile), and it
drains an area eight times greater, or 2 square miles. The maximum
depth of 86 feet was observed in the centre of the loch off the mouth
of the Allt Loch Laraig. The volume of water is estimated at 244
millions of cubic feet, and the mean depth at 33 feet. The breadth of
the loch at the position of the deepest sounding is 27 times the depth.
The shore development is small (I'll), and the insulosity 0'002. The
deeper water occurs in the western part of the loch, though the 25-feet
area sends a narrow tongue into the eastern part. The 75-feet area
in the centre of the loch is small, with a narrow tongue extend-
ing towards the northern shore. The areas between the consecutive
contour-lines, and the percentages to the total area of the loch, are
as follows : —

0 to 25 feet 81 acres 48'0 per cent.

25,, 50 „ 43 „ 25-6

50,, 75 „ 35 „ 20-6

Over 75 , 10 , 58

169 ,, 100-0

Temperature Observations. — The following series of temperatures
was taken in the centre of the loch at 6 p.m. on July 29,
1902: —

226 BATHYMETRICAL SURVEY OF

Surface 55°'5 Fahr.

5 feet 55°-5 „

10 „ 55°-3 ,,

20 „ 55° -3 „

30 ,, 55°-2 ,,

50 „ • 55°'l „

60 ,, 54C>3 ,,

70 ,, 500>9 ,,

This series shows that the temperature was practically constant
down to 50 feet, the fall being less than J°, thence a fall of 0°-8 between
50 and 60 feet, and then a rapid fall of 30>4 between 60 and 70 feet.

Loch Kernsary (see Plate XL VII.). — Loch Kernsary is situated to
the north-east of Inveran, at the foot of Loch Maree, into which it
drains through the little Loch Poll Uidhe a' Chro' and the Inveran
river. There was no boat passage into Poll Uidhe a' Chro', and it was
found impossible to carry the boat across. The ground around Loch
Kernsary is low, except to the north, where Meall an Leathaid Dharaich
rises to over 400 feet. The island near the south-western shore in the
main portion of the loch is an artificial crannog, but nothing is known
of its history N

Loch Kernsary was surveyed on July 25 and 26, 1902 ; the elevation
of the water-surface above the sea was determined, by levelling from
Loch Maree, as being 68'0 feet. The keeper stated that the water would
rise 2J feet above, and fall 1 foot below this level, but a drift-mark
was observed 8-4 feet above the surface of the water.

Loch Kernsary is about 1 J miles in length, with a maximum breadth
of nearly half a mile, the mean breadth being about 350 yards. Its
waters cover an area of about 200 acres, and it drains directly an area
of nearly 7| square miles, but since it receives the outflow from Loch
Ghiuragarstidh, its total drainage area is over 8J square miles — an area
27J times greater than that of the loch. The maximum depth of 93
feet was observed about 250 yards from the north-western extremity of
the loch. The volume of water is estimated at 333 million cubic feet,
and the mean depth at 38 feet. The breadth of the loch at the position
of the deepest sounding is ten times the depth. The shore development
is 2*51, and the insulosity 0*008.

The floor of Loch Kernsary is rather irregular, there being two
25-feet areas and four 50-feet areas. The main 25-feet area extends
throughout the greater part of the loch, while the smaller one lies in
the south-western part of the loch. Three of the 50-feet areas are
enclosed by the main 25-feet area : the north-western one containing
the deepest water in the loch, the central one having a maximum depth
of 66 feet, and the south-eastern one a maximum depth of 69 feet,
therefore falling just below sea-level; the fourth 50-feet area, based

THE FRESH-WATER LOCHS OF SCOTLAND. 227

on soundings of 51 and 53 feet, lies in the centre of the south-western
part of the loch. The 75-feet area is situated in the north-western part
of the loch, and sinks below sea-level, the deepest spot being 25 feet
below the level of the sea.

The areas between the consecutive contour-lines, and the percentages
to the total area of the loch, are as follows : —

0 to 25 feet 72 acres 35 '8 per cent.

25,, 50 „ 69 „ 34-4

50,, 75 „ 39 „ 19-8

Over 75 , 20 . lO'O

200 , 100-0

Thus 70 per cent, of the lake-floor is covered by less than 50 feet of
water.

Temperature Observations. — A series of temperatures was taken in
the deep part of the loch at 2.30 p.m. on July 25, 1902, with the
following results : —

Surface 57°'0 Fahr.

10 feet 57°-0 „

25 „ 56°-8 „

50 „ 53°'0 „

80 ,, 50°-2 „

This series shows an almost constant temperature down to 25 feet,
then a rapid fall of 3°'8 between 25 and 50 feet, and a further fall of
2°-8 between 50 and 80 feet.

Loch Gliiuragarstidh (see Plate XLVII.). — Loch Ghiuragarstidh
lies about half a mile to the north of Loch Kernsary, into which it
drains by the Allt Loch Ghiuragarstidh. The islands are covered by a
few feet of peat and soil, and have many fir trees growing on them.
The loch was surveyed on July 28, 1902; the elevation of the lake-
surface was determined, by levelling from Loch Kernsary, as being
11 6' 7 feet above mean sea-level.

Loch Ghiuragarstidh is about 1200 yards in length, with a maximum
breadth of about 370 yards, the mean breadth being about 230 yards.
Its waters cover an area of 58 acres, and it drains an area nearly ten
times greater, or about 560 acres. The volume of water is estimated
at 23 million cubic feet, and the mean depth at 9 feet. The breadth of
the loch at the position of the deepest sounding is 27 times the depth.
The shore development is 1-63, and the insulosity 0'028. The bottom is
very irregular in the southern half of the loch, large boulders and reefs
rising above the surface of the water in many places. In the northern
half the lake-floor is more regular, and it is only in this part that the
depth exceeds 10 feet, the maximum depth of 37 feet having been

228 BATHYMETRICAL SURVEY OF

observed in the centre of the loch near the northern end. The area of
the lake-floor covered by less than 25 feet of water is about 56 acres, or
96 per cent, of the total area.

Temperature Observations. — Temperatures taken at 5 p.m. on July
28, 1902, in the deep part of the loch gave the following results : —

Surface 57°'5 Fahr.

5 feet 57°'5 ,,

7 „ 57°'5 „

15 „ 57°'l „

25 „ ... 56°'0 ,,

Loch a' Bhaid-Luachraich (see Plate L.). — Loch a' Bhaid-Luachraich
(or Goose Loch) lies about a mile to the east of Loch Ewe, into which
it drains at Aultbea by the Allt Bheithe. It is surrounded by low,
rounded hills, steep only towards the south-east, covered with peat or
morainic material. It is extremely irregular in outline, and in fact
may almost be looked upon as two lochs with a connecting arm. The
south-western part is shallow, the maximum depth observed in it
being 43 feet, while the north-eastern part is much deeper, having a
maximum depth of 143 feet; the maximum depth observed in the
connecting arm was 15 feet. The lower part where the stream leaves
the loch is thickly overgrown with reeds and rushes, and weeds are
abundant in the two bays at the head of the loch. It was surveyed
on July 29 and 30, 1902, and the elevation was determined, by levelling
from bench-mark, as being 309*6 feet above the sea; when levelled by
the officers of the Ordnance Survey on August 3, 1870, the elevation
was found to be 310*5 feet above sea-level.

Loch a' Bhaid-Luachraich is over 1 J miles in length, and over a mile
in maximum breadth, with a mean breadth of one-third of a mile. It
covers an area of half a square mile, and it drains directly an area of
3J square miles, but since it receives the outflow from Loch Mhic'
Ille Riabhaich its total drainage area is nearly 4 square miles — an area
eight times greater than that of the loch. The volume of water is
estimated at 486 million cubic feet, and the mean depth at 34 feet. The
bottom in the south-western part of the loch is rather irregular, while
the north-eastern part forms a simple deep basin, the maximum depth
of 143 feet having been observed near the centre at the widest part of
this portion. Section A-B is taken across this wide portion at the
position of the deepest sounding. The areas between the consecutive
contour-lines, and the percentages to the total area, are as follows: —

0 to 25 feet 184 acres 56'2 per cent.

25 ,, 50 ,, 84 ,, 25-5 „

50,, 75 „ 17 ,, 5-3

75,, 100 „ 17 „ 5-0

Over 100 ,, 26 „ 8*0

328 . 100-0

THE FRESH- WATER LOCHS OF SCOTLAND. 229

These figures indicate that the average slope is gentle in the
shallower water, and much steeper in depths exceeding 50 feet, but
it will be observed from the map that the contour-lines approach
very close to the shores in certain places, indicating a steep slope in
these positions.

Temperature Observations. — The surface temperature at 11.45 a.m.
on July 29, 1902, was 56°'l, and at 4 p.m. on July 30, when the
following series was taken, it was more than half a degree lower : —

Surface ... ... ... ... ... ... ... 55° '4 Fahr.

10 feet 55°'4 „

20 „ 55°'4 „

30 „ ~ 55°'4 „

50 „ 53°'6 „

7-1 „ 49°-8 „

85 , 48°'4 „

120 „ ... 47°'2 „

This series shows a constant temperature from the surface down to
30 feet, then a slight fall of l°-8 between 30 and 50 feet, followed by a
rapid fall of 5°-2 between 50 and 85 feet, thence to the bottom a slight
fall of 10<2, the total range of temperature from surface to bottom
being 8°-2.

Loch Mhic' Ille Riabhaich (see Plate L.).— Loch Mhic' Ille Riabhaich
is a small, irregular, shallow loch lying to the south-east of Loch a'
Bhaid-Luachraich (into which it flows by the Allt na Criche), surrounded
by low, rounded hills ; 011 one of the islands is a fortress, but nothing
seems to be known of its history. It was surveyed on July 31, 1902,
but its elevation above the sea could not be determined; from the
contour-lines on the Ordnance Survey maps it is apparently rather
less than 600 feet above the sea. It is half a mile in length from
north to south, and rather less in maximum breadth from south-east to
north-west. It covers an area of about 36 acres, and drains an area of
nearly three-quarters of a square mile. Two soundings of 12 feet were
taken near the north end at the outflow, and a sounding of 10 feet off
the eastern shore of the larger island ; with these exceptions, the lake-
floor is covered by less than 10 feet of water. The volume is estimated
at 8 million cubic feet, and the mean depth at 5J feet.

The temperature of the surface water at 12.30 p.m. on July 31,
1902, was 57°-0 Fahr.

Loch nan Dailthean (or na Daline), lying to the south-west of Loch
Mhic' Ille Riabhaich, and flowing into Loch Thuirnaig (an inlet of
Loch Ewe), was visited by the Lake Survey, but not sounded. It is
said to be so shallow that cows may walk over the whole of it, except
a small hole near Thuirnaig House, in which the depth is 4 feet.

230 BATHYMETRICAL .SURVEY OF

Loch an t-Slagain (see Plate L.). — Loch an t-Slagain lies to the east
of Slaggan bay, at the entrance to Loch Ewe, into which it flows by
the Allt an t-Slagain. It is surrounded by low hills, and receives the
outflow from several small lochs lying to the east and south. It
was surveyed on August 11, 1902; the elevation above the sea was
determined by levelling to be 103-5 feet; when visited by the officers
of the Ordnance Survey on May 5, 1875, its elevation was 102*6 feet
above sea-level. The height of the highest drift-mark observed was
2-3 feet above the surface of the water on August 11, 1902, so that the
range of level is probably between 3 and 4 feet. The loch trends in a
north-west and south-east direction, and is two-thirds of a mile in
length by one-third of a mile in maximum breadth. Its waters cover
an area of about 77 acres, and it drains an area 17 times greater, or
over 2 square miles. The maximum depth of 55 feet was observed
comparatively very near the south-eastern shore. The volume of water
is estimated at 55 million cubic feet, and the mean depth at 16| feet.

Loch an t-Slagain is of simple conformation, the 10-feet area being
continuous from end to end, but the deeper water is cut into two
portions by the shallower water around the central islands. To the
north-west of the islands two soundings of 25 feet were recorded,
while the deepest part of the loch lies to the south-east of the islands.
The areas between the consecutive contour-lines, and the percentages
to the total area, are as follows : —

0 to 10 feet 27 acres 35 '3 per cent.

10,, 25 „ 39 „ 50-6

25,, 50 „ 8 „ 10-6 „

Over 50 , 3 , 3'5

77 ,, 100-0

Thus 86 per cent, of the lake-floor is covered by less than 25 feet of
water, and the major portion is covered by water between 10 and 25
feet in depth.

Loch Sguod (see Plate L.). — Loch Sguod lies less than half a mile
from the western shore of Loch Ewe (opposite the Isle of Ewe), into
which it flows by the Uidh Chro. It drains the higher ground to the
west and south-west by several streams flowing through the low peat
bogs which surround the loch on all sides. It was surveyed on August
15, 1902, but its elevation above the sea could not be determined; the
water may rise 2 feet above its level on the date mentioned. Loch
Sguod is nearly three-quarters of a mile in length, with a maximum
breadth of nearly half a mile, the mean breadth being a quarter of a
mile. Its waters cover an area of about 107 acres, and it drains an
area 26 times greater, or 4J square miles. The maximum depth of

THE FRESH- WATER LOCHS OF SCOTLAND. 231

14 feet was recorded towards the eastern shore. The volume of water
is estimated at 32 million cubic feet, and the mean depth at 7 feet, or
half the maximum depth. The loch is quite simple in conformation,
but the deeper water is confined to the central and north-eastern parts
of the loch, approaching very close to the eastern shore, off which the
slope is steep. The area of the lake-floor covered by less than 10 feet
of water is about 78 acres, or 73 per cent, of the total area. The
temperature of the surface water at 9 a.m. on August 15, 1902, was
57°-2 Fahr.

Loch an Drainc (see Plate L.). — Loch an Drainc (or an Druing) lies
to the north-west of Loch Sguod, and flows through Loch nan Eun
(which was not sounded) and the Abhuinn Leumnach into The Minch,
about 2J miles to the west of the entrance to Loch Ewe. The ground
around the loch is mostly covered with peat, and to the east are low
but -steep knolls 200 to 300 feet in height, dotted over with small and
beautiful lochs, while to the west and south there is a fairly steep
ascent to Maol Breac, An Cuaidh, and Bac an Lethchoin (over 900
feet), the sides of which are well wooded. It was surveyed on August
16, 1902, but the elevation above the sea could not be determined;
the water may rise 2 to 3 feet above its level on this date. Loch an
Drainc trends north-north-west and south-south-east, and is nearly
three-quarters of a mile in length, with a maximum breadth of over
one-third of a mile, the mean breadth being nearly a quarter of a mile.
Its waters cover an area of about 96 acres, and it drains an area 22
times greater, or nearly 3J square miles. The maximum depth of 55
feet is approximately centrally placed, but nearer the western than the
eastern shore. The volume of water is estimated at 108 million cubic
feet, and the mean depth at 26 feet, or nearly half the maximum
depth. The loch forms a simple basin, and, considering its area, is
comparatively deep, the 25-feet area being over half a mile, and the
50-feet area one-fifth of a mile, in length. The areas between the
consecutive contour-lines, and the percentages to the total area, are
as follows : —

0 to 25 feet 47 acres 48 '9 per cent,

25,, 50 „ 45 „ 47-2

Over 50 , 4 , 3'9

96 , 100-0

Temperatures taken at 3 p.m. on August 16, 1902, gave 590>0 at
the surface, and 58°*0 at a depth of 40 feet.

Deposits. — The deposits from certain parts of Loch an Drainc, as
well as of Loch Sguod, were of a strikingly pink colour, and a sample
from a depth of 20 feet in Loch an Drainc was found to be coherent

232

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when dry, and when wet plastic and creamy, not unlike cocoa and milk
of a pink brown colour. The material is made up of probably 90 per
cent, of clayey matter with minute mineral particles less than O05 mm.
in diameter, the remaining 10 per cent, consisting of mineral particles
with a mean diameter of 0'15 mm. Quartz is the principal mineral
species, but small grains of pink microcline-felspar are very abundant,
and it is apparently to this mineral that the pink colour of the deposit
is due; the microcline shows cross-hatching, and is much kaolinized.
The washed mineral grains have a decided pink tinge, which is, how-
ever, much more pronounced in the fine washings. Besides quartz and
felspar, white and brown mica, hornblende, garnet, and magnetite were
observed. There is little or no vegetable matter.

The particulars regarding the lochs in this basin are collected
together in the table on p. 232 for convenience of reference and com-
parison. From this table it will be seen that in the fourteen lochs under
consideration, which cover an area of nearly 15 square miles, nearly
2500 soundings were taken, or an average of 167 soundings per square
mile of surface. The aggregate volume of water contained in the lochs
is estimated at 44,500 millions of cubic feet, and the area draining
into them is 185J square miles, or 12J times the area of the lochs.

NOTES ON THE GEOLOGY OF THE LOCH MAREE DISTRICT.

By B. N. PEACH, LL.D., F.R.S., and J. HORNE, LL.D., F.R.S. With
Geological Map (Plate LI.). Published by permission of the
Director of the Geological Survey.

The Loch Maree district presents features of special geological
importance relating to the subdivisions of the Archaean rocks, to the
topography of the old pre-Torridoniaii land surface, and to the series
of terrestrial movements which affected the north-west Highlands in
post-Cambrian time. Throughout the mountainous region, stretching
north to Dundonnell forest and south to Achnashellach and Glen
Shieldaig, excellent sections are to be found showing the geological
structure of that region.

The Archaean rocks (gi on map), lying to the west of the great post-
Cambrian displacements, occur mainly in the north-west of the area,
where they form a broad tract of mountainous ground between Loch
na Sheallag and Loch Maree, and westwards by Torrisdale to Gairloch.
There is also an important development of them on both sides of Loch
Torridon above Loch Shieldaig, and they likewise appear as inliers,
surrounded by Torridon Sandstone, as, for instance, on the southern
slope of Beinn Dearg north of Liathach. Within the territory affected

234 BATHYMETRICAL SURVEY OF

by the post-Cambrian movements there are masses of displaced
gneiss, of which the most important lies immediately to the north
of Kiiilochewe; others appear further north on Mullach Coire Mhic
Fhearchair, and far to the south on Glas Bheinn, on Torr na h-Iolaire,
and at Coulags in Glen Carron. Over much of the region they form
lofty ground and give rise to prominent peaks, as, for example, Beinn
Lair (2817 feet), Beinn a' Chaisgein Mor (2802 feet), and Beinn Airidh
Charr (2593 feet), all north of Loch Maree.

Throughout this area there is a remarkable development of those
types of Archaean rocks that have affinities with plutonic igneous
products, consisting mainly of massive and foliated, pyroxenic, horn-
blendic, and micaceous gneisses. Along the northern margin of this
district, between Loch na Sheallag and Gruinard Bay, the original
characters of the rocks that enter into the fundamental complex are
well displayed. The various stages in the separation of the ferro-
magnesian from the quartzo-felspathic constituents, and the gradual
development of mineral banding in the massive gneisses are there clearly
shown. In that area, also, the intrusive character of the basic dykes
traversing the gneiss in a west-north-west direction is proved beyond all
doubt. Passing southwards to the tract lying south of Poolewe, both
the gneisses and the intrusive dykes have been thrown into an anticlinal
fold, which is represented on the Geological Survey Map (Sheet 91).
Here we find that, under the influence of mechanical stresses, there
has been differential movement of the rock constituents, and linear
foliation has been developed in the basic dykes — the foliation being
parallel with the pitch of the folds. Further south in the Torridon
district biotite gneisses prevail, which are traversed by bands of horn-
blende-schist representing the original basic dykes.

Of special interest is the development of crystalline schists, that
have affinities with rocks of sedimentary origin, north of Loch Maree
and near Gairloch. The prominent members of this series are quartz-
schists, mica-schists, graphitic-schists, limestones, and dolomites, with
tremolite, garnet, and epidote, which are there associated with a massive
intrusive sheet of hornblende-schist. Lithologically some of these
crystalline schists closely resemble the altered sediments in the Eastern
Highlands. The quartz-schists, mica-schists, and limestones are well
exposed in various folds between Letterewe and Glen Tulacha, west of
Lochan Fada, pierced by the great sill of hornblende-schist forming
Beinn Lair and Beinn Airidh Charr (BG on map). The original
relations of these altered sediments to the gneisses that have affinities
with plutonic igneous rocks have been obscured by subsequent earth
stresses. But along their outer margin they are bounded by gneiss
apparently underlying them, and they are visibly overlain by gneiss
with basic dykes, the whole series being affected by a common system of
folds.

THE FRE8H- WATER LOCHS OF SCOTLAND. 235

One of the most remarkable geological features of the Loch Maree
district is the evidence relating to the topography of the primeval land
surface on which the Torridoniaii sediments were laid down. Between
the head of Loch Maree and Strath na Sheallag, where the overlying red
sandstone has been partly removed by denudation, it is possible to trace
the direction of the old valleys and the orientation of the ancient
peaks. On the eastern slope of Ben Slioch, near Glen Fh'asaigh, the
observer may climb one of these hills, which rises to a height of
about 2000 feet in the midst of the Torridon Sandstone, and trace the
alternation of breccia and sandstone filling the ancient valley. Similar
evidence is obtained further north in the mountainous region near the
head of Glen na Muic. Where these deeply-eroded valleys are pre-
served, breccias of local origin frequently appear at the base of the
Torridon Sandstone. In the Loch Maree district this formation has
been subdivided into three groups : a lower, consisting of epidotic grits,
dark and grey shales, with calcareous bands and red sandstones; a
middle, composed of a great thickness of false-bedded grits and sand-
stones with scattered pebbles ; an upper, comprising chocolate-coloured
sandstones, micaceous flags, with dark shales and calcareous bands.
The members of the lower group are well displayed in the district near
Talladale and Slattadale, on the south-west shore of Loch Maree ; those
of the middle group are typically developed in the mountains round
Loch Torridon, from which district this system takes its name, while
the upper group appears in the islands north of Gruinard. Throughout
this region this formation (t on map) reaches a vast thickness, for on
the shores of Loch Torridon it rises on Liathach from the sea-level to
a height of over 3000 feet. In the mountains between Slioch and An
Teallach these sandstones have a gentle dip towards the south-east;
in the Torridon district they are nearly horizontal, while further south
they form a low arch.

As indicated in our previous notes on the geology of the Assynt
district, the Torridon Sandstone is separated from the overlying
quartzites by an unconformability, which in some parts of the Loch
Maree area is not so prominent as in Assynt. On An Teallach in
the Dundomiell forest and southwards towards Mullach Coire Mhic
Fhearchair, the Cambrian quartzites are inclined at a higher angle
to the south-east than the Torridon Sandstone. In the area lying to
the west of the post-Cambrian displacements we find at various localities
the normal Cambrian sequence in ascending order — 1, the basal
quartzites (a1 on map); 2, the pipe-rock (a2); 3, the Fucoid beds (a3).
This sequence is displayed in the Dundonnell forest, on the western
slope of Ben a' Vuinie near Kinlochewe, on the west declivity of Meall
a' Ghuibhais south of Loch Maree, and on Beinn Eighe. Within these
limits the Fucoid beds have yielded at several localities well-preserved
trilobites and other organic remains of Lower Cambrian age. The

236 BATHYMETRICAL SURVEY OF

Cambrian limestone rarely appears in the undisturbed area; in the
displaced masses west of Glas Bheinn towards the head of Loch Kishorn
it is largely represented.

The evidence bearing on the .post-Cambrian movements obtained in
the Loch Maree district is of special interest. On referring to the
map, it will be seen that the belt affected by these movements runs
southwards from Dundonnell by Kinlochewe, Beinn Eighe, and the
Coulin forest to Glen Carron and Loch Kishorn. Throughout this
area the geological structure is extremely complicated, but certain
sections may be referred to as illustrating the continual variation in
the relations of the rocks. The simplest type is met with in the
Dundonnell forest, where on the west slope of Creag Rainich there are
two powerful thrusts running parallel with each other for some distance
in a north-north-east and south-south-west direction. West of these
lines of displacement the Cambrian sequence is undisturbed from the
basal quartzites to the Fucoid beds. On the horizon of the latter the
first powerful thrust is met with, which brings forward a slice of
Torridon Sandstone with a core of Archaean gneiss. Not far to the east
the second thrust supervenes, which ushers in the crystalline schists
overlying the Moine thrust-plane. A repetition of this structure in a
more complicated form is found in the tract between Glen Fhasaigh
and the heights of Kinlochewe, where the mass of displaced gneiss
with its intrusive dykes is admirably displayed between the Moine
thrust to the east and the outcrop of the Kishorn and Kinlochewe
thrust-plane west of Ben a' Vuinie.

In the region stretching south from the head of Loch Maree by
Beinn Eighe and the Coulin and Achnashellach forests to Loch Kishorn
the structure is more complicated. For to the west of the two great
lines of displacement just referred to, which have been traced south to
Loch Kishorn and Glen Carron, the Torridon Sandstone and Cambrian
strata have been repeated by a series of inverted folds and minor
thrusts. Hence we find strips of Cambrian quartzite alternating with
Torridon Sandstone, the strata having a general dip towards the south-
east as if they formed part of a normal ascending sequence. The clear
sections, however, on Beinn Eighe, on Sgurr Dubh, Beinn Liath Mhor,
Sgurr Ruadh, and other peaks, show the overfolding and reversed
faults which are the prominent features of the structure of that region.
Still further south, towards the head of Loch Kishorn, and west of the
slice of Archaean gneiss overlying the Kishorn thrust-plane, there is a
constant repetition of the Fucoid beds and Cambrian limestone by
inverted folds and reversed faults.

In the Loch Maree district, as in Assynt, there is evidence of
the development of new structures resulting from the post-Cambrian
movements. The deformation of the Torridon Sandstone, west of the
Moine thrust, is well displayed in the stream south of the Kinlochewe

THE FRESH- WATER LOCHS OF SCOTLAND. 237

Hotel, where the grits have been made schistose, and where the felspars
have been partially broken down and reconstructed. Near the outcrop
of the Kishorn thrust, west of Glen Carron, the Lewisian gneiss is
sheared and rolled out, passing into flaser gneiss and schist with a
platy or fluxion structure.

East of the Moine thrust, which runs south from Dundonnell by
Loch an Nid, the heights of Kinlochewe, and Loch Coulin to Glen
Carron, the area represented on the map is occupied by crystalline
schists of a remarkably uniform type. They consist mainly of flaggy
granulitic quartzose schists and mica-schists, with prominent belts of
garnetiferous muscovite-biotite schists. The latter are well developed
on Fionn Bheinn, north of Achnasheen, and on Sgurr Mor Fannich,
where they form conspicuous crags. Near the Moine thrust, and,
indeed, for some miles to the east of the plane of that thrust, the
Eastern or Moine schists have a persistent dip to the south-east. In
the Fannich mountains they are over-folded on a stupendous scale,
and similar evidence is obtained in the group of mountains north of
Achnasheen.

Reference must now be made to the faults that affected the area after
the post-Cambrian thrusts. Of these by far the most important is the
great line of displacement that crosses the region in a north-west and
south-east direction, coinciding with the long axis of Loch Maree,
which may be termed the Loch Maree fault. It has been traced in a
north-west direction along the river Ewe, by the south margin of Loch
Ewe, towards Loch an Drainc, where the Torridon Sandstone on the
north-east side is faulted down against the Lewisiau gneiss at Poolewe.
At Kinlochewe this dislocation has been traced up Glen Dochartie and
onwards in the direction of Ledgowu. Indeed, the probable con-
tinuation of this fault has been recently found far to the south-east — in
the basin of the Conon. Where the line of fault is not obscured by
drift, it gives rise to a prominent feature on the surface of the ground.
This powerful fault shifts the outcrops of the Moine and Kishorn
thrust-planes, and likewise of the overfolded strata associated with
these thrusts. It further shifts the outcrop of the normal fault in
Glen Fhasaigh, which runs in a north-east direction between the head
of Loch Maree and Lochan Fada (see map). The continuation of the
Fhasaigh fault is to be found in Glen Grudie, on the south side of Loch
Maree, so that its outcrop is shifted at least for a distance of two miles
by the Loch Maree dislocation.

In the north-west part of the area, in Isle Ewe, and in the pro-
montory between Loch Ewe and Gruinard Bay, there is a strip of
Triassic Sandstone (/ on map) thrown down by two powerful faults.

Throughout the Loch Maree district, and especially in the moun-
tainous region embracing the Torridon Sandstone and the Cambrian
quartzite, there is evidence of intense glaciation. During the climax

238 BATHYMETRICAL SURVEY OF

of the glacial period, even the highest mountains in the Loch Maree
district were overridden by the ice. Some of the evidence pointing to
this conclusion may here be referred to. Along the top of Ben Slioch
(3217 feet), which, as already indicated, is composed of Torridon Sand-
stone, blocks of thrust Archaean gneiss, Cambrian quartzite, and
Moine schists are met with, all of which have been derived from the
east. Similar evidence is obtained on Meall Ghuibhais (2882 feet), on
the south side of Loch Maree. Again, in the Coulin forest, on the lofty
ridge running south from Sgurr Dubh (2566 feet) to Beinn Liath Mhor
(3034 feet), striae have been recorded pointing in a westerly direction at
elevations ranging from 1750 to 2000 feet. Blocks of crystalline schist
derived from the area east of the Moine thrust, and occasional frag-
ments of thrust Archaean gneiss, appear on this ridge. Further south
on Sgurr Ruadh, ice-markings pointing a few degrees to the north of
west occur at an elevation of 2500 feet. The top of Ruadh Stac (2919
feet), on the east side of Glen Kishorn, is finely glaciated, the striae
pointing W. 25° N. The summit of Meall a' Chinn Dearg (3095 feet),
composed chiefly of Torridon Sandstones and grits, is strewn with
transported blocks of Cambrian quartzite. Similar evidence might be
adduced regarding that part of the Applecross area which is shown in
the south-west corner of the map. For there, on Beinn Bhan (2936
feet), striae have been recorded underneath the 2750 feet contour-line
trending W. 13° to 20° N. Blocks of the Eastern or Moine schists
appear at that level, and are fairly plentiful below 2500 feet. From
these facts the inference seems obvious that during the maximum
glaciation the western part of Ross-shire must have been completely
overridden by ice moving in a westerly direction towards the sea.

The westerly flow of the ice is confirmed by the transport of the
boulders in the drift deposits, which consist mainly of moraines in the
area lying to the west of the Moine schists, and these contain numerous
blocks of quartzose-schist and mica-schist derived from the east.

After the disappearance of the great ice-sheet there ensued a period
of confluent valley glaciers. The direction of the ice-flow during this
later glaciation is represented on the map by feathered arrows. On
referring to the map, it will be seen that the prominent mountain
groups north and south of Loch Maree formed independent centres of
glaciation. In many of the valleys there is a splendid development of
both lateral and terminal moraines. The closing phases of the glaciation
of the region are indicated by the moraines encircling some of the high
corries, and by similar deposits resting on the 50-feet beach at the head
of Loch Torridon, where they have been recorded by our colleague,
Mr. Hinxman.

A glance at the map will show that Loch Maree is by far the largest
rock basin in that district ; but as it lies along the line of a powerful
fault, which has given rise to a prominent feature in the topography

THE FRESH-WATER LOCHS OF SCOTLAND. 239

of the region, we prefer not to discuss its features in connection with
the theory of the glacial origin of lake basins.

Loclian Fada is a simple rock basin resting partly on Torridon
Sandstone and partly on Lewisian gneiss. Along the greater part of
its course it coincides with an old pre-Torridonian valley, trending in a
west-north-west direction. At its eastern end it is bounded by the
continuation of the Glen Fhasaigh fault, which brings down the
Cambrian quartzite, Fucoid beds, Serpulite grit, limestone, and over-
lying Archaean gneiss above the Glen Logan or Kishorn thrust-plane.
The sudden deepening of the loch at its lower end is evidently related
to this fault, because harder and more durable strata on the east side
of this fault have been brought against the softer Torridon Sandstone
to the west. It is important to note that the downthrow side of this
fault is towards the east ; in other words, the eastern floor of Lochan
Fada is not faulted down to the west. It is interesting to note that the
deepest part of the basin, and the deepest sounding (248 feet), lie
between Slioch and Ben Tarsuinn, where the erosion of the ice during
the maximum glaciation would probably be greatest.

Loch Garbhaig, which is situated to the north of Ben Slioch, is a
small lake over a mile in length, and evidently a rock basin from the
appearance of Lewisian gneiss at its exit, where it is drained by the
Amhainn na Fuirneis. The soundings prove the existence of two
basins separated by a ridge, the eastern one reaching a depth of 93 feet,
and the western 50 feet close to its outlet. This lake lies mainly along
the junction of the Archaean rocks and Torridon Sandstone, the older
rocks forming the greater part of the north shore, and the red sand-
stone the larger part of the south margin. A tongue of Torridon
breccia occupies a hollow in the Archaean rocks on the north shore,
where it rests on a mass of hornblende-schist. This breccia appears in
an island in the loch, which forms part of the ridge separating the two
basins. The loch may therefore be regarded as a rock basin eroded by
ice, mainly out of Torridon Sandstone along its line of junction with
the Archaean floor.

Loch Kernsary is very irregular in shape, and has four basins below
the 50-feet level, the deepest sounding — 93 feet — being found near its
north-west extremity. The Archaean gneiss forms part of its north-east
shore, while the Torridonian rocks floor the remaining portions, save
near the west limit of the north shore, where a boss of Lewisian gneiss
projects through the Torridon Sandstone. As the Torridon sandstones
and conglomerates dip at angles varying from 20° to 35° to the north-
west, we may infer that those sediments are resting on a very uneven
floor of gneiss. The bed of the lake, therefore, may here correspond
with the pre-Torridonian surface, the softer Torridon Sandstone being
more easily removed than the more durable gneiss. Striae pointing in
a north-west direction are found round the lake, the trend of which is

240 BATHYMETRICAL SURVEY OF

slightly oblique to the long axis of the loch, but almost parallel to
that of the 50-feet basins. The latter in turn have their longer axes
somewhat oblique to the strike of the Torridonian strata.

Loch Ghiuragarstidh is a shallow loch lying along the strike of the
Torridon Sandstone, with an exposure of Lewisian gneiss near its outlet,
its greatest depth being 37 feet. A long ridge of sand and gravel,
probably a moraine, occurs near its mouth, so that this lake may lie
partly in drift and partly in rock.

Loch Tollie is a true rock basin of very irregular shape, surrounded
by Lewisian gneiss, the deepest sounding being 86 feet. This basin
belongs to the shallow plateau type so common in the Archaean area
in the west of Sutherland. Its irregularity is due to the folding and
intense shearing of the component members of the Lewisian gneiss in
that region. Glacial striae are met with at several localities round the
loch, varying in direction from W. 10° N. to W. 41° N. The dominant
strike of the foliation of the gneiss is west-north-west and east-south-
east. The long axes of the bays in the loch are more in accordance
with the direction of the ice-flow than with the strike of the foliation.

Loch Glair lies partly in moraine drift and partly in thrust
Torridonian strata. Drift occurs at the outlet and along its western
margin, and all the islands are composed of moraines.

Loch Coulin is separated from Loch Clair by an alluvial fan brought
down by the Allt na Luib. The river Coulin has silted up the greater
part of the upper end of the lake, and its limits have been still further
restricted by detritus borne downwards by the streams on the north.

THE FRESH- WATER LOCHS OF SCOTLAND. 241

LOCHS OF THE SHIEL BASIN.

ONLY two lochs belonging to this basin were sounded, viz., Lochs Shiel
and Dilate ; one or two other small lochs within the basin (the principal
one being Lochan Dubh, at the head of Glen Hurich) were not sounded.

Loch Shiel (see Plates LII. and LIIL). — Loch Shiel is one of the
larger Scottish fresh-water lochs, having a total length of 17^ miles. In
this respect it is inferior only to Lochs Awe, Ness, and Lomond, which
are 25J, 24^, and 22 J miles in length respectively, and is closely followed
by Loch Shin, which is 17^ miles in length. Its elevation above the sea
is only 11 J feet, so that a slight subsidence of the strip of land through
which the river Shiel flows would convert it into an arm of the sea.
Seals occasionally make their way into this loch from the sea at the
present time. The principal upper portion of the loch trends in a
north-east and south-west direction, but about 6 miles above the outflow
there is a bend in the outline of the loch, and the lower portion trends
almost due west. The river Shiel follows a north-westerly course for
about 2 miles before emptying itself into Loch Moidart. The scenery
around the loch is very fine, becoming grand and wild towards the
head. At the foot of the loch the surrounding ground is low, but on
proceeding up the loch mountainous country borders the loch on both
sides, culminating in heights exceeding 3000 feet at the head of Glen
Finnan. To 'the south rises Ben Resipol (2774 feet), between Loch
Shiel and Loch Sunart; to the east Sgor an Tarinachain (2474 feet),
Meall Mor (2487 feet), Meall nan Creag Leac (2474 feet), Glas Garbh
(2369 feet), Meall Doire na Mnatha (2094 feet); to the north Beinn
nan Tom (2603 feet), Streap (2988 feet), Sgor Choileam (3164 feet),
Sgor nan Coireachan (3133 feet), Fraoch-bheinn (2489 feet); to the
west Beinn Odhar (2895 feet), Druim Fiaclach (2851 feet), a' Chroit-
bheinn (2178 feet), and Beinn Gaire (2179 feet). The principal feeders
are the river Finnan, Amhainn Shlatach, and Gallop river, which enter
the loch at its head, Glenaladale river entering about 6 miles down on
the north-western shore, and the river Polloch (bearing the outflow
from Loch Dilate) entering about 11 miles down on the south-eastern
shore, where the bend in the trend of the loch occurs. There are

242 BATHYMETRICAL SURVEY OF

numerous small islands and a few larger ones, the largest being Eilean
Gleann Fhionainn at the head of the loch, while on Eilean Fhiaiiain,
at the narrows towards the foot of the loch, are the remains of St.
Finnan's Church and a romantic burying-place of the Clanranald. At
the head of the loch stands Prince Charlie's monument, erected by the
late Colonel Macdonald, of Glenaladale, on the spot where that ill-fated
prince raised his standard. Salmon, grilse, sea-trout, and brown trout
abound in the loch, and yield fair sport, some of the salmon and trout
being very heavy.

Considering its great length, Loch Shiel is very narrow, for at no
place does the loch attain a width of a mile, the maximum breadth
being about nine-tenths of a mile, and this occurs at the great bend in
the outline of the loch, opposite the entrance of the river Polloch. The
mean breadth of the loch is less than half a mile, being only 2| per cent,
of the length — a smaller percentage than has been observed in any of
the larger lochs surveyed by the Lake Survey, the lochs most nearly
approaching it in this respect being Loch Shin with 3 per cent., and
Loch Ness with 4*3 per cent. The waters of Loch Shiel cover an area
of about 4840 acres, or over 7J square miles, and it drains directly an
area of over 72 J square miles, but, since it receives the outflow from
Loch Dilate, its total drainage area is about 85J square miles — an area
over eleven times greater than that of the loch. Over 700 soundings
were taken, the maximum depth recorded being 420 feet, about 4 miles
from the head of the loch, between the heights of Beinn a' Chaoruinn
and Beinn Odhar Bheag to the north-west, and of Meall nan Creag
Leac to the south-east. The volume of water contained in the loch is
estimated at 27,986 million cubic feet, and the mean depth at 132|
feet, or nearly 32 per cent, of the maximum depth. Loch Shiel was
surveyed on July 2 to 9, 1902. The elevation of the lake-surface above
the sea was determined, by levelling from bench-mark, as being 11 '4
feet ; when levelled by the officers of the Ordnance Survey on November
6, 1897, the elevation was found to be 12 feet above sea-level. The
water may rise 4 to 5 feet higher than the level given above.

The floor of Loch Shiel is on the whole rather irregular. The
50-feet contour-line encloses a continuous area extending from close to
the upper end to within 2 miles from the lower end at Acharacle, but
all the deeper contours are broken up so as to enclose two or more
isolated areas. The 50-feet contour follows approximately the general
outline of the loch, but it is in places of a sinuous character. At the
head of the loch it extends both to the north-west and south-east of
Eilean Ghleann Fhionainn. About 2 miles down there are sinuosities
in the contour on both sides of the loch, due to a tongue of deep water
projecting between the south-eastern shore and the island Sgeir Ghiubh-
sachain, and to a shoaling of the water off the north-western shore
from 33 to 15 feet. Further down, off the north-western shore, above

THE FRESH- WATER LOCHS OF SCOTLAND. 243

the entrance of the Glenaladale river, there is a twist in the 50-feet
contour, where the water shoals from 55 to 20 feet. Still further down,
opposite the entrance of the Allt na Dalach, sinuosities in the 50-feet
contour occur on both sides of the loch, the water shoaling off the south-
eastern shore from 47 to 35 feet, and off the north-western shore from
41 to 19 and 22 feet. The last-mentioned shoaling occurs to the north-
east of Eileanan Comhlach, at the entrance of the Allt a' Ghiubhais,
and it is curious to observe a similar shoaling on the opposite (south-
west) side of the island from 41 to 18 and 21 feet, while between the
island and the mouth of the stream a depth of 32 feet was observed.

FIG. 41. LOCH SHIEL, FROM PRINCE CHARLIE'S MONUMENT.

(Photograph by Mr. T. Ar. Johitrtvit, M.B., C.M., F.R.S.E.)

Towards the lower end of the wide part of the loch, and almost due
south of Eilean Druim nan Laogh (or Heron island, as it is now called
in the district), there is, near the middle of the loch, a shoal covered by
only 2 or 3 feet of water. During the visit of the Lake Survey the
regular mail steamer was laid up for repairs, having shortly before
struck on this shoal and damaged the propeller. The captain of the
steamer supplied information as to the position of the shoal, and the
local gillie employed by the surveyors stated that in calm weather the
bottom can be seen, but in the stormy weather prevailing at the time
of the survey he was unable to find it, so that it must be of very small
extent, for deep soundings were recorded near the spot indicated. The

244 BATHYMETRICAL SURVEY OF

same gillie stated that a shoal bank extended from Ruadh Bac na Moine
in an approximately south-west direction towards the opposite shore;
this was confirmed by fishermen, and is probably indicated by the
outward bend of the 50-feet contour-line at that place.

The 100-feet contour-line is less sinuous in character than the 50-feet
contour, the main basin being about 12 miles in length, extending
from near the head of the loch to the narrows at Eilean Fhianain,
with two small subsidiary basins — one off Rudha Leathan, about 3J
miles from the foot of the loch, based on a sounding of 112 feet;
the other between the promontory on the south-eastern shore called
Rudha Torr a' Chonnaidh and the outlying islands, about 7 miles from
the head of the loch, based on a sounding of 148 feet. A remarkable
rise in the bottom was observed within the main 100-feet basin, about
a mile above the entrance of the river Polloch, where soundings of
84 and 43 feet were taken, surrounded on all sides by about 150 feet
of water. The contour of the lake-floor along this line of soundings is
shown in cross-section C-D on the map (Plate LII.).

The main 200-feet basin is nearly 8 miles in length, approaching
to within half a mile from the head of the loch, and extending as far
down as Eileanan Comhlach. There are two small subsidiary basins,
separated from the main basin by an interval of over half a mile,
between the entrance of the Allt na Claise on the south-eastern shore
and the entrance of the An Garbh-allt on the north-western shore.
This line of soundings shows a curious configuration of the bottom,
which rises in the central part of the loch and sinks again on both sides
nearer the shore : thus, on proceeding from south-east to north-west the
water deepens to 201 feet, then shoals to 122 feet, then deepens again to
172, 209, and 224 feet, shoaling again towards the north-western shore.
It is interesting to note the close proximity of these two small deep
basins to the rise covered by 43 feet of water already mentioned. The
200-feet contour shows a peculiar loop off the north-western shore,
about 4 miles from the head of the loch, where the water shoals from
199 to 163 feet.

The principal 300-feet basin is distant about a mile from the head
of the loch, and extends down the loch for over 4 miles, enclosing the
deepest parts of the loch. Separated from this basin by an interval
of a quarter of a mile (in which the greatest depth is 282 feet) is a
second small basin based upon a sounding of 307 feet, and after a
similar interval (in which the greatest depth is 284 feet) there is
a third 300-feet basin 2 miles in length, having a maximum depth of
385 feet. Within this third basin there is a slight rise of the bottom
covered by 288 feet of water; the line of soundings on which this
rise is situated is shown in cross-section E-F on map (Plate LIIL).

There are two small basins with depths exceeding 400 feet, the
smaller about 3 miles from the head of the loch, based on soundings

THE FRESH- WATER LOCHS OF SCOTLAND. 245

of 416 and 419 feet, separated by an interval of three-quarters of a
mile (in which the greatest depth is 375 feet) from the larger, which
is less than a mile in length and encloses the maximum depth of the
loch (420 feet), recorded near the north-eastern end of this larger basin,
and over 4 miles from the head of the loch. The line of soundings,
which includes the deepest one, is shown on cross-section G-H on map
(Plate LIIL).

FIG. 42. LOCH SHIEL, FROM HIGH GROUND AT THE HEAD OF THE LOCH.

(Photograph by Mr. Darid Brigham.)

From the foregoing description, it will be noticed that in Loch Shiel
the deeper water occurs towards the head of the loch. Proceeding from
Acharacle, at the foot of the loch, one must row 2 miles up before
encountering a depth of 50 feet ; a further 1 J miles before meeting with
a depth of 100 feet, and this merely a small patch, a further 1J miles
having to be traversed before reaching the main 100-feet basin, or a
total distance of 5 miles from the foot of the loch. The main 200-feet
basin is distant about 9 miles, the lower 300-feet basin nearly 10 miles,
and the principal 400-feet basin over 12 miles, from the foot of the
loch.

246

BATHYMETRICAL SURVEY OF

The areas between the consecutive contour-lines drawn at equal

intervals, and the percentages to the total area of the loch, are as
follows : — •

2632 acres 54 '4 per cent.

9G8 ,, 20-0

711 ,, 14-7

484 „ lO'O

45 <H» „

0 to 100 feet
UK),, 200 „
•200,, 300 ,,
300,, 400 ,,
Over 400 „

4840

KKVO

This table shows that more than half of the entire floor of Loch Shiel
is covered by less than 100 feet of water, and about three-fourths by
less than 200 feet, while only 1 per cent, is covered by water exceeding
400 feet in depth. The slope of the bottom is on the whole gentle, but
in certain places deep water was found comparatively close inshore,
and the consequent crowding of the contour-lines indicates a steeper
slope than usual in these positions.

Temperature Observations. — Numerous observations were made on
the temperature of the surface water of Loch Shiel during the week
spent on the survey, the range observed being 8°'2, from 540>2 to 620>4.
Three serial temperatures were taken beneath the surface, with the
following results : —

TABLE OF SERIAL TEMPERATURES TAKEN IN LOCH SHIEL.

Depth in feet.

July 5, 1902,
6p.m.
Off Scamodale.

July 8, 1902,
Off Eilean Druim
nan Laogh.

July 9, 1902,
5 p.m.
3 miles from head
of loch.

0 Fahr.

0 Fahr.

0 Fahr.

0

57-1

55-9

56-5

5

54-9

10

57-0

54-5

20

56-3

54-4

56-5

30

55-5

...

50

50-2

54 :0

56 '-0

75

...

50-9

...

100

47-0

47-0

47-4

130

46-2

...

200

45-7

45:2

280

45-3

300

...

...

45:2

400

45-3

In this table the observations are arranged chronologically, but the
series given in the first column was taken about midway between the
other two series, the second column giving a series taken towards
the foot, and the third column a series taken towards the head, of the
loch. The central series in the first column was taken three days
earlier than the others, and is therefore not strictly comparable ; it
shows a higher temperature in the surface waters, and a lower tempera-

THE FRKSH- WATER LOCHS OF SCOTLAND. 247

ture at a depth of 50 feet than in either of the others. The temperature
observed near the foot of the loch was lower at all depths than that
observed towards the head, the difference amounting to 2° at 20 and
at 50 feet, and to 0°'4 at 100 feet. The most pronounced fall in
temperature was recorded between 50 and 100 feet towards the two
ends of the loch, but between 30 and 50 feet in the central series (first
column). The range of temperature shown by these serial observations
is about 12°, while the extreme range of all the observations from
surface to bottom during the week spent on the survey is over 17°.

Loch Dilate (see Plate LIV.). — Loch Dilate (or Doilate) lies about
1J miles to the east of the lower portion of Loch Shiel, into which it
flows by the river Polloch entering Loch Shiel about 6 miles above
its outflow. The ground between the two lochs is low, the fall from
Loch Dilate to Loch Shiel being only 10J feet, but high and moun-
tainous country surrounds Loch Dilate in all other directions. The
principal feeder is the river Hurich, which takes its rise in Lochan
Dubh at the head of Glen Hurich, and after a course of 6 miles empties
itself into the east end of Loch Dilate. The loch trends east and west,
and is nearly 1^ miles in length. It is widest towards the east end,
where the maximum breadth is over one-third of a mile, the mean
breadth being about one-seventh of a mile. Its waters cover an area
of about 142 acres, or nearly a quarter of a square mile, and it drains
an area fifty-eight times greater, or nearly 13 square miles. Forty-five
soundings were taken in Loch Dilate, the maximum depth observed
being 55 feet. The volume of water contained in the loch is estimated
at 145 million cubic feet, and the mean depth at 23J feet, or 43 per
cent, of the maximum depth. The loch was surveyed on July 8, 1902,
and the elevation of the lake-surface above the sea, by levelling from
bench-mark, was found to be 22*0 feet. When levelled by the officers of
the Ordnance Survey on October 16, 1867, the elevation was found to
be 23*4 feet above sea-level.

Loch Dilate forms a simple basin, the deeper water being centrally
placed, and the contour-lines following approximately the outline
of the loch. A sounding of 12 feet was recorded off the bay in the
south-east corner of the loch, apparently surrounded by shallower
water, though possibly continuous with the 10-feet area, but this is
the only irregularity in the lake-floor indicated by the soundings.
Along the central portion of the southern shore the contour-lines
closely hug the shore, indicating a comparatively steep slope in this
locality. A section along the central line of the loch from west to
east is shown in section A-B on the map. The areas between the
contour-lines drawn in at equal intervals, and the percentages to
the total area of the loch, are as follows : —

248 BATHYMETRICAL SURVEY OF

0 to 25 feet 78 acres 55*4 per cent.

25,, 50 „ 49 „ 34-3

Over 50 , 15 . 10'3

142 , 1000

Temperature Observations. — The following serial temperatures were
taken at 3 p.m. on July 8, 1902, in the deepest part of Loch Dilate : —

Surface 62° '3 Fahr.

10 feet ... 62°-3 „

20 „ 62°-3 „

25 „ 6l°-5 ,,

30 „ 55° -3 „

50 „ ... 53°-3 „

This series shows a constant temperature from the surface down
to a depth of 20 feet, a slight fall of 0°-8 between 20 and 25 feet, then
a very rapid fall of 60>2 between 25 and 30 feet (a fall exceeding 1° per
foot of depth), and a further fall of 2° between 30 and 50 feet, the
extreme range of temperature being 9° Fahr.

THE FRESH- WATER LOCHS OF SCOTLAND. 249

LOCHS OF THE AILORT BASIN.

LOCH EILT is the only loch to be dealt with here ; the few very small
hill lochs within the basin were not surveyed.

Loch Eilt (see Plate LV.). — Loch Eilt lies about 1J miles to the east
of the head of Loch Ailort (into which its outflow is carried by the
river Ailort), and about 4 miles to the west of Glenfinnan. The hills
around it rise steeply up to a height of over 1500 feet, the highest
points exceeding 2000 feet. It was formerly considered a good loch
for salmon and sea-trout; but Mr. Harvie-Brown believes that the
blasting operations during the construction of the Mallaig extension of
the West Highland railway resulted in the destruction of a large
amount of spawn and fry, and that now the fish are greatly disturbed
by the passage of the trains across the bays on the south shore.

Loch Eilt trends east and west, and is 3J miles in length, with a
maximum breadth of half a mile, the mean breadth being one-fifth of
a mile. Its waters cover an area of about 424 acres, or two-thirds of
a square mile, and it drains an area of 12 square miles. Over 250
soundings were taken, the maximum depth recorded being 119 feet.
The volume of water contained in the loch is estimated at 686 million
cubic feet, and the mean depth at 37 feet. The loch was surveyed on
July 9 and 10, 1902; the elevation of the lake-surface was found, by
levelling from bench-marks, to be 96-4 feet above the sea. The keeper
stated that the water might rise about 3 feet above, and fall about
9 inches below, this level. During the night of July 9 and 10, 1902,
the water rose nearly 10 inches.

Loch Eilt is naturally divided into three portions by two narrow
constrictions in its outline, the western portion being by far the largest
and deepest, covering an area of about 360 acres, while the area of the
central and eastern portions is in each case about 32 acres. The
western portion is connected with the central portion by a channel
6 feet in depth, with a rocky islet in the centre, the sides of the
channel being also of rock in situ, thus dividing the loch into two
rock-basins ; the central portion is separated from the eastern portion
by detritus brought down by the Allt a' Choire Bhuidhe, the channel

250 BATHYMETRICAL SURVEY OF

between them having a depth of 7 feet. The small eastern and central
basins are quite simple in conformation, the maximum depth observed
in the eastern one being 52 feet, and in the central one 70 feet. The
floor of the large western basin is much more irregular, there being
four areas with depths exceeding 50 feet : (1) a small area near the
east end, based on a sounding of 52 feet; (2) the main 50-feet area,
which encloses the deepest part of the loch, over a mile in length, and

FIG. 43. LOCH EILT, LOOKING EAST.

(Photograph by Mr. David Brigham.)

with a rocky islet rising to the surface near its western margin ;
(3) a small area between the large island (Eilean Mor) and the northern
shore, based on a sounding of 55 feet; and (4) a small area near the
west end, based on two soundings of 55 feet. At the extreme west end
of the loch, between the two islands, a depth of 40 feet was recorded.
The 75-feet area is about half a mile, and the 100-feet area about a
quarter of a mile, in length, occupying the wide central part of the
western basin, but rather nearer the east than the west end. The
deepest part of the loch falls below sea-level (the 100-feet contour-line

THE FRESH-WATER LOCHS OF SCOTLAND.

251

corresponding approximately with the level of the sea), and is flat-
bottomed in character, as shown in cross-section C-D on the map.

The areas between the consecutive contour-lines drawn in at equal
intervals, and the percentages to the total area of the loch, are as
follows : —

0 to 25 feet
25,, 50 „
50,, 75 „
75,, 100 „
Over 100 ,

187 acres

111 „

88 „

20 „

18 „

424

per cent.

26-0

20-9

4-8

4-2

100-0

Temperature Observations. — The temperature of the surface water
in Loch Eilt during the two days spent on it varied from 58° to 60°
Fahr. On July 10, 1902, three series of temperatures were taken
beneath the surface, one in each of the three basins into which the loch
is divided, with the following results : —

Depth in feet.

Loch Eilt (eastern

basin).

July 10, 1902,
2-30 p.m.

Loch Eilt (central

basin).

July 10, 1902,
3'30 p.m.

Loch Eilt (western

basin).

July 10, 1902,
5p.m.

0 Fahr.

0 Fahr. 3 Fahr.

Surface. 58*0

58-1

60-0

10

58O

58-1

60-0

20

58-0

58-1

60-0

27'5

55-7

57-7

60-0

35

52-8

53-6

59-7

50

50-7

52-8

54-8

75

...

53-0

100

...

...

51 -0

These series show a constant temperature down to 20 feet in each
case, but the water in the deep western basin was 2° warmer than in
the other two basins. Beyond the depth of 20 feet, again, the tem-
perature was about 2° higher in the western basin than in the central
basin, and 2° higher in the central basin than in the eastern basin, so
that at a depth of 100 feet in the western basin the temperature was
rather higher than at a depth of 50 feet in the eastern basin. The
water in the western basin was warmer at all depths than that in the
central basin, and in the central basin than in the eastern basin. To
explain this peculiar distribution of temperature in the waters of Loch
Eilt on the afternoon of July 10, 1902, the weather conditions during
the few preceding days must be taken into account. The wind had
been blowing strong from the north-east from the 3rd till the afternoon
of the 9th. Rain commenced to fall about 6 a.m. on the 9th, and
continued till about 8 a.m. on the 10th, so that during the twelve hours
from 9 p.m. on the 9th to 9 a.m. on the 10th the surface of the loch rose

252 BATHYMETRICAL SURVEY OF

9J inches. About 11.30 a.m. on the 10th the wind rose from the west,
and by 4 p.m. was blowing a gale, so much so that the greatest difficulty
was experienced in keeping the boat in position for the 5 p.m. series
of temperatures. It would thus appear that the easterly winds of the
previous week had blown the warm surface water into the western
portion of the loch, and the west wind of the 10th had not yet had
time to reverse this effect; the fact that the area draining into the
western basin is nearly double that draining into the other two basins
would doubtless accentuate this result, since more water would enter
the western basin than the other basins, and this inflowing water at
this season of the year would be warmer than the water of the loch.
The range of temperature from surface to bottom in the eastern basin
was 7°-3 Fahr., the greatest fall being 5°-2 between 20 and 35 feet;
in the central basin the range was 5°'3, the greatest fall being 4°-5,
also between 20 and 35 feet; in the western or main basin the range
was 9° (representing the extreme range observed throughout the entire
loch), and the greatest fall was 4°-9 between 35 and 50 feet.

THE FRESH- WATER LOCHS OF SCOTLAND. 253

LOCHS OF THE NAN UAMH BASIN.

THE lochs to be dealt with here are Loch Dubh, between the head of
Loch Ailort and the head of Loch nan Uamh, and Lochs Mama and
na Creige Duibhe lying to the north-east. Loch Doir' a' Gherrain in
Ardnish could not be sounded, because there was no boat on it at the
time of the visit of the Lake Survey.

Loch Dubh (see Plate LVL). — Loch Dubh is a small loch situated
at the head of the peninsula of Ardnish, which separates Loch Ailort
from Loch nan Uamh, the two branches of the sound of Arisaig. The
Mallaig extension of the West Highland railway runs along its southern
shore, and the outfall flows through the old bed of the little Lochan
Deabhta, which has been completely drained by the railway, leaving
only a channel through it for the escape of the waters from Loch Dubh.
After leaving Lochan Deabhta the outfall joins the Schoolhouse burn,
which has been deflected, thence into the Arnabol burn, falling into
the head of Loch Beag, an inlet of Loch nan Uamh. It is surrounded,
except on the western side, by low though steep hills, which impart
a dark and sullen appearance to the loch, hence its name — the Black
loch. Considering its superficial area, it is the deepest loch visited by
the Lake Survey.* Its great depth, and the remarkable temperature
conditions discovered in it, well repaid the trouble pf carting a boat
from Loch nan Uamh and carrying it down to the loch. Its catchment
area is very small, and it would seem that the unpleasant taste of its
water, resembling that of a stagnant pool, is due to the small amount
of fresh water entering it. This unpleasantness is probably something
more than mere taste, for attempts to stock the loch with trout have
been unsuccessful, the fish rapidly dying ; eels, however, abound in it.

Loch Dubh trends in a north-west and south-east direction, the
broadest part being rather nearer the south-east end. Its length is

* The deepest lake in East Prussia is, according to Halbfass (Globus, Bd. 86, p. 187,
September 15, 1904), the Wuchsnigsee, which is about 1J miles in length, and has a
maximum depth of about 210 feet. Loch Dubh is less than half a mile in length, and its
maximum depth is 153 feet.

254 BATHYMETRICAL SURVEY OF

under half a mile, its maximum breadth one-sixth of a mile, and its
mean breadth one-tenth of a mile. Its waters cover an area of about 32
acres, and it drains an area eight times greater, or about 262 acres.
Sixty-five soundings were taken, and the maximum depth observed was
153 feet, which bears the ratio to the length of the loch of 1 to 15.
This low ratio is only equalled by the little loch on Eilean Subhainn
in Loch Maree, and the loch which most nearly approaches it is Loch
Fender in the Tay basin, in which the ratio is as 1 to 22, followed by
Loch Dhugaill, near Kishorn, in which the ratio is as 1 to 27. Among
the larger Scottish lochs, the nearest approach is found in Loch Treig,
with a ratio of depth to length of 1 to 62. The volume of water
contained in the loch is estimated at 86,956,000 cubic feet, and the mean
depth at nearly 63 feet, or 41 per cent, of the maximum depth. The
loch was surveyed on July 12, 1902; the elevation of the lake-surface
above the sea was found, by levelling from bench-marks, to be 103-0
feet ; when visited by the Ordnance Survey officers on August 6, 1869,
the elevation was 103*3 feet above sea-level. No drift-marks were seen,
but the keeper stated that the annual range in level was about 9 inches.
Loch Dubh is very simple in conformation, the contour-lines follow-
ing approximately the shore-line. Near the north-west end there is a
slight rise of the bottom, as shown in section A-B on the map, but
otherwise the lake-floor slopes down regularly to the deepest part,
which lies towards the north-eastern shore. The maximum depth of
153 feet was observed at a distance of about 120 feet from this shore,
giving a slope of 59° ; the height of the hill immediately adjoining is
240 feet, and the slope 35°, hence the slope from the top of the hill to
the bottom of the loch is one of 45°. The areas between the consecutive
contour-lines drawn in at equal intervals, and the percentages to the
total area of the loch, are as follows : —

Oto 50 feet 14 '8 acres 407 per cent.

50,, 100 ,, 8-9 „ 30-9

100,, 150 ,, 7-6 „ 26-5

Over 150 , 0'5 . 1-9

31-8 . 100-0

Temperature Observations. — A most interesting series of temperatures
was taken in Loch Dubh at the time of the survey, as given in the first
column of the following table. The loch was revisited in March, 1903,
when the water was found to be uniform in temperature from surface
to bottom, as given in the second column of the table —

THE FRESH-WATER LOCHS OF SCOTLAND.

255

Depth in feet.

Loch Dubh.
July 12, 1902,
3 p.m.

Loch Dubh.
March 28, 1903.

°Fahr.

°Fahr.

0

59-0

41-0

10

59-0

16

58-9

tt

20

56-0

..

25

53-7

35

51-5

50

47-1

41-0

75

44-1

41-0

100

43-6

40-9

150

43-5

40'9

The series taken in March calls for no discussion, but the series
taken in July is remarkable for the low temperature of the deep water
at this season of the year, and for the great range of temperature from
surface to bottom. Compared with the temperatures recorded in Loch
Shiel a week earlier in the same month, we find the temperature in
Loch Dubh l°-7 lower at the bottom in 150 feet than in Loch Shiel in
420 feet, and in Loch Morar (the deepest of all Scottish lochs), ten days
earlier in the same month, a temperature equal to that at the bottom
of Loch Dubh was recorded only after descending to a depth of 250
feet. The extreme range of temperature shown by the series in Loch
Dubh amounts to 15°*5, while the series taken in Loch Shiel shows a
range of only 12°, and the series in Loch Morar shows a range of only
13°, from surface to bottom. The extraordinary temperature conditions
observed in Loch Dubh may probably be accounted for (1) by the great
depth of the loch compared with other lochs of similar area ; (2) by the
small extent of its drainage area, so that very little rain-water enters
the loch ; and (3) by the small area of the loch and the steepness of the
surrounding hills reducing the mixing effect of the wind to a minimum.

Lochs Mama and na Creige Duibhe doubtless formed at no distant
date one sheet of water, which was gradually separated into two portions
by the deposition of material brought down by the Allt Dearg. This
is evidenced by the fact that locally the name Mama is applied to
both divisions, but in this place that name is restricted to the western
basin, the name na Creige Duibhe being applied to the larger and
deeper eastern basin. The connecting stream is about 60 yards in
length, with a depth of 7 to 8 feet, the fall from Loch na Creige Duibhe
to Loch Mama being less than a foot. The tract of alluvium separating
the two lochs was about 2^ feet above the water of Loch Mama, and
the keeper stated that he had often seen it flooded when the lochs were
high. The hills along the northern and southern shores of the lochs
rise steeply up to heights exceeding 1000 feet, approaching 2000 feet
along the northern shores, down the sides of which a few torrents rush

256 BATHYMETRICAL SURVEY OF

after heavy rains. The two lochs trend east and west, and the outflow
from Loch na Creige Duibhe passes into Loch Mama, and thence by
the Gleann Mama into Loch nan Uamh.

Loch Mama (see Plate LVL). — Loch Mama is over one-third of a
mile in length, one-eighth of a mile in maximum breadth, and one-
twelfth of a mile in mean breadth. Its waters cover an area of about
17 acres, and it drains directly an area of two-thirds of a square mile,
but since it receives the outflow from Loch na Creige Duibhe its total
drainage area is over 2 square miles, an area seventy times greater than
that of the loch. Nearly 40 soundings were taken, the maximum depth
observed being 44 feet. The volume of water contained in the loch is
estimated at 11 million cubic feet, and the mean depth at 14 J feet. The
loch was surveyed on July 11, 1902, and the elevation of the lake-
surface above the sea was determined from spot-levels as being 359
feet. It forms a simple basin, the deepest part being found towards
the east end. The areas between the contour-lines, and the percentages
to the total area, are as follows : —

0 bo 10 feet 8'0 acres 46 '9 per cent.

10,, 25 „ 6-4 ,, 37-5

Over 25 , 2'6 , 15 "6

170 , 100-0

Loch na Creige Duibhe (see Plate LVL). — Loch na Creige Duibhe is
four-fifths of a mile in length, one-eighth of a mile in maximum breadth,
and one-fourteenth of a mile in mean breadth. Its waters cover an
area of about 36| acres, and it drains an area twenty-four times greater,
or about 1 \ square miles. Over 70 soundings were taken, the maximum
depth recorded being 93 feet. The volume of water is estimated at
52 million cubic feet, and the mean depth at 32 \ feet. The loch
was surveyed on the same day as Loch Mama (July 11, 1902); the
elevation of the lake-surface above the sea, from spot-level and by
comparison with Loch Mama, was found to be 359*7 feet. An inspection
of the map shows Loch na Creige Duibhe to be (like Loch Mama) a long
narrow basin of very simple conformation. It is much deeper than Loch
Mama, and the deeper water approaches nearer to the west than to the
east end, that is to say, nearer to the alluvial cone separating the two
lochs. A similar state of matters has been noted in the case of Lochs
Voil and Doine in the Forth basin, formerly a continuous loch, now
divided into two portions by the deposition of material brought down
by the river, where deep water approaches close to the dividing
promontory of land on both sides. *

The areas between the consecutive contour-lines drawn in at equal

* See p. 9.

THE FRESH- WATER LOCHS OF SCOTLAND. 257

intervals, and the percentages to the total area of the loch, are as

follows : —

0 to 25 feet 21 '2 acres 58 '1 per cent.

25 „ 50 ,, 6-9 „ 19-0

50,, 75 „ 5-1 „ 14-1

Over 75 , 3-2 , 8 '8

36-4 , 100-0

Temperature Observations. — The surface temperature observed in
Loch na Creige Duibhe on the date of the survey was 57°'4, in the
stream between the two lochs 57°'l, and in Loch Mama 56°'5. The
following serial temperatures were taken in the deepest part of Loch
na Creige Duibhe at 4.45 p.m. on July 11, 1902 : —

Surface 57°'4 Fahr.

10 feet 57°'4 „

20 ,, 57°'4 „

30 ,, 53°-0 „

50 ,, 50°'8 ,,

75 „ 49°-2 „

90 ., - 48°'S „

This series shows a constant temperature down to 20 feet, then a
fall of 4°-4 between 20 and 30 feet, and a further fall of 2°-2 between
30 and 50 feet, the extreme range of temperature from surface to bottom
being 8°-6.

The details regarding the lochs in the Shiel, Ailort, and nan Uamh
basins are collected together in the table on p. 258 for convenience of
reference and comparison. From this table it will be seen that in the
six lochs under consideration nearly 1200 soundings were taken, and
that the aggregate area of the water-surface is over 8J square miles, so
that the average number of soundings per square mile of surface is 139.
The aggregate volume of water contained in the lochs is estimated at
about 29,000 millions of cubic feet. The area drained by these lochs
is nearly 100 square miles, or 11 J times the area of the lochs.

Geology of the Loch Shiel Catchment Basin. — Though the basin of
Loch Shiel has not been surveyed by the Geological Survey, we under-
stand that certain members of the staff have examined the rock cuttings
on the line of railway between Loch Eil and Kinlochailort. The rocks
exposed in these cuttings consist of muscovite-biotite gneiss and flaggy
mica-schists, which are included in the Moine series of crystalline
schists by the Geological Survey. The general strike of these strata
is north-east and south-west, so that in all likelihood they are continued
to the south-west along both sides of Loch Shiel. This conclusion is
supported by the fact that on the lofty watershed between Loch Shiel

258

BATHYMETRICAL SURVEY OF

•a

R

e

I

B ^

^ *

55 .5

s>

Ratio to
area of
loch.

O CO CC O CO CO ^

co o5 c^i "^ co co co

f^H 00 00 00 •<* O5 <— i
p-H 1C r-t <N CO —1

1

ill

*

C^ r— i IO i— I CO O5 !>•
•* 00 O •"* •* O O5

g 2 2 ® ^ ^ i

c
1

11

S ^ cp 8 8 p S

t^ O O O O O 00

Volume

in minion
cubic feet.

QC ^ 00 CC ^O >-^ CO
Oi> ^-1* CO Oi>

h

1

g ^ 01 CO 0 1^

0 g

•p

03

X

O^ t^* Ot) *O ^7 ^

s co 2 - ^

sl"s

CO t> O5 P O5 ip

^H (70 ^H ^H 4t< 6)

CO rfH CO -* CO CO

I

ll

CO (M CO CO OO •— I

II

| S S g § 3

Mean
breadth

1^1

C^ O1 ^O CC 00 ^~*
S! - SI 5

d

1

CO O O O !>• 00

T»< ~- 1 (55 r-H p P

O O O O O O

I a

oo t^ ^H t^ co co

00 CO 0 ^H F-H r-H

1

O O O O O O

!

1

1^- ^H CO O O O

1^

3

It

O »C •* »O ^ 00 — i

£ ^ ® 2

•

£r

•1 1

1

TH P ^ p 1- P

i

.1

"® "S J "£ o S
1 S 3 & S x

THE FRESH- WATER LOCHS OF SCOTLAND. 259

and Loch Linnhe these muscovite-biotite gneisses have been mapped by
the Geological Survey. These schists and gneisses, which are supposed
to represent altered sediments, are traversed by numerous veins of
pegmatite and dykes of diorite, dolerite, and basalt.

On the watershed between Glen Hurich and Glen Scaddle, on the
crest of Sgor Dhomhail (2915 feet), there is a mass of foliated granite,
and, further to the south-west, the later igneous intrusions of the
Strontian district may enter the Loch Shiel catchment basin.

NOTES ON THE BIOLOGY OF THE LOCHS IN THE SHIEL DISTRICT.
By JAMES MURRAY.

Of the six lochs surveyed, tow-nettings were taken in four, and a
shore-netting in a fifth. The biology presented little of special interest.
Diaptomus laciniatus was found in two of the lochs (Shiel and Eilt) ;
these are the most southerly lochs in which this northern species was
observed by the Lake Survey, though it has been recorded by Dr. Scott
from one loch (Loch Doon) much farther south.

Loch Shiel. — Owing to the great abundance of Holopedium, which
choked up the nets, it was difficult to collect other animals in any
numbers. The most plentiful animals were : Diaptomus gracilis,
Diaptomus laciniatus, Cyclops strenuus , Bosmina obtusirostris, Bytho-
trephes, Polyphemus, six species of pelagic Rotifers (including Flos-
cularia pelagica), and Dinobryoii. The plants noted were : Xanthidium
antilopeum, Staurastrum gracile, and Staurastrum braziliense. Lobelia
and LittnreUa were in flower at the upper end of the loch.

Loch Dilate. — As compared with Loch Shiel, the most notable
features of this loch were : the greater abundance of life, the absence of
Holopedium and Diaptomtw Jaciniatus, and the presence of Diaphajio-
soma brachyurum in considerable numbers. Among the organisms
observed were: Diaptomus gracilis, Cyclops strenuus, Synchceta
pectinate, Plcesoma truncata, Dinobryon, Peridiniu?n, two species of
Ceratium (C . hirundinella and C . cornutum), Anabce.ua flos aqua with
its adherent Vorticellce.

Loch Eilt. — Life was abundant, the characteristic animals being
Holopedium, Diaptomus laciniatus, Cyclops strenuus, Anurcea cochlearis,
Notholca longispina, and Polyarthra. Leptodora and Bythotrephes were
scarce. Bosmina obtusirostris and a variety approaching B. longispina
were seen. The brilliant red and blue Rotifer, Notops pygmceus, was
plentiful. Some immature specimens of Diaptomus probably belonged
to D. gracilis. On the mud in the deepest part of the loch were numbers
of a pretty little green larva of an insect, enclosed in transparent flask-
shaped cases.

260 BATHYMETRICAL SURVEY OF

Loch Dubh. — This little loch, remarkable for its great relative depth
and temperature conditions, resembling those in a great lake, was
examined on two occasions. On the first visit in July, 1902, the surface
temperature was 59° Fahr., while on the second visit in March, 1903,
the temperature throughout was about 41° Fahr. Notwithstanding
this difference in temperature there was little difference in the animals
observed on the two occasions. Those found in July were : Diaptomus
gracilis (blue and red, grey, red, blue), Cyclops strenuus, Bosmina
obtusirostris (small, purple), Daphnia lacustris (all pale red), Eurycercus,
Polyphemus, Triarthra, Polyarthra, Anurcea cochlearis, Conochilus,
Ceratium hirundinella, Dinobryon. In March all. the same animals
were found, except Polyphemus, and there were in addition a few larvae
of Corethra (phantom larvae), Notholca foliacea, a second species of
Ceratium (C . cornutum — less common in lakes), Mallomonas. A very
small form of Asterionella occurred. Near the shore large spheres of
Ophridium were found on the weeds. In the mud from the bottom were
many Rhizopods of the species Cyphoderia ampulla, Difflugia pyri-
formis, D. globulosa, and D. arcula. Lobelia and Myriophyllum were
growing along the shores.

Loch na Creige Duibhe. — As this loch was only examined by means of
a net thrown out from the shore, it is probable that some of the pelagic
animals may have been missed. The animals seen were : Diaptomus
gracilis (reddish), Cyclops strenuus (yellow), Alonopsis elongata,
Chydorus sphcericus, Anurcea cochlearis, Bosmina obtusirostris, Arcella
vulgar is. A few of the commonest filamentous Algae and Desmids were
seen. Asterionella was scarce.

THE FRESH- WATER LOCHS OF SCOTLAND. 261

LOCHS OF THE CONON BASIN.

FOURTEEN lochs draining into the Cromarty firth were surveyed by the
staff of the Lake Survey, viz., Lochs Crann, a'Chroisg, Gown, Achanalt,
a* Chuilinn, Fannich, Luichart, Beannachan, Achilty, Garve, Kinellan,
Ussie, Glass, and Morie. The majority of these lochs drain by the river
Conon into the head of the Cromarty firth, while Lochs Glass and Morie
drain by independent streams, which fall into the Cromarty firth on
its north-western shore. It has been found convenient, also, to include
in this place a description of Loch Eye, situated between Cromarty
firth and Dornoch firth. The drainage area under consideration is
indicated in the index map of the district (Fig. 44), by reference to
which the relations between the various lochs will be readily understood,
and extends from the mouth of the Cromarty firth on the east to the
heights of Carn Breac and An Groban on the west, Carn Chuinneag
on the north, and Sgorr a' Choir-Ghlais on the south. The total area,
as measured by the planimeter on the 1-inch Ordnance Survey maps, is
over 770 square miles, and of this total 336 square miles (or one-half)
drain into the lochs now to be dealt with, as will be seen from the
summary table.

The headwaters of the basin take their rise on the flanks of Carn
Breac, flowing by various streams into Loch na Moine Moire and Loch
an t-Sior (which were not sounded), thence into Loch Crann and Loch
a' Chroisg, the outflow from which is carried by the river Bran into
Loch Achaualt and Loch a' Chuilinn, and thence into Loch Luichart.
Shortly after leaving Loch a' Chroisg the river Bran receives the outflow
from Loch Gown, which is fed by the Allt Gharagain, taking its rise
on the flanks of Moruisg (3026 feet), and shortly before entering Loch
Luichart the river Bran is joined by the river Fannich bearing the
outflow from Loch Fannich, which is fed by various streams draining
the flanks of a grand series of mountains exceeding 3000 feet in height.
After the junction of the Bran and the Fannich the river receives the
name of Conon, and shortly after leaving Loch Luichart it is joined by
the river Meig, bearing the outflow from Loch Beannachan, taking its
rise among lofty mountains culminating in Sgurr a' Chaoruinn (3452
feet). Still further on the river Conon is joined by the Black Water,
bearing the outflow from Lochs Garve and Achilty, and taking its rise

262

BATHYMETRICAL SURVF.Y OF

far to the north on the flanks of Beinn Dearg (3547 feet). Still further
on the river Conon is joined by the river Orrin, and finally falls into
the head of the Cromarty firth at Dingwall. The river Glass, which
in its course flows through Loch Glass, rises on the flanks of Beinn nan
Eun, and empties itself in the Cromarty firth at Balconie Point. The
river Alness, which flows through Loch Morie, rises on the flanks of
Beinn a' Chaisteil, and falls into the Cromarty firth at Alness Point.
The geology of the district is dealt with by Drs. Peach and Home,
whose notes are appended, as well as a few biological notes by Mr. James

O I 2 3 4 5

' English Miles

FIG. 44. INDEX MAP OF THE CONON BASIN.

Murray. Mr. R. M. Clark, B.SC., who took part in the survey of the
lochs in the Conon basin in 1902, has supplied us with several series
of temperatures taken by him the previous summer (1901) in Lochs
Achilty, Garve, Achanalt, a' Chuilinn, and a' Chroisg, which are here
incorporated.*

* These temperature observations, taken by Mr. Clark in the summer of 1901, are
interesting, as compared with the observations taken in the same lochs in the summer
of 1902, when viewed in connection with the atmospheric conditions in the two seasons.
It will be observed that all the readings taken in the superficial waters of these lochs
in 1901 are higher than those taken in 1902, and this is evidently related to the warmer
season in the first-named year. Thus the mean temperature over Scotland for July,

1901, was 61°-8 Fahr., or 3° above the long-period average for that month, while for July,

1902, it was 54°-4, or 4£° below the average ; for August, 1901, tie mean was 570<5, or
1° above the average, while for August, 1902, the mean was 53° '9, or 2^° below the average.
The nearest station to the Couon basin lochs from which observations are available is
Inverness, and the mean temperature there for July, 1901, was 61°-0, or 4° above the long-
period average, while for July, 1902, the mean temperature was 45°-4, or 3£° below the

THE FRESH-WATER LOCHS OF SCOTLAND. 263

Loch Crann (see Plate LVIL). — Loch Crann is a small shallow loch
situated a short distance to the west of Loch a* Chroisg, and lying at a
slightly higher level. Its striking characteristic is the large area of
hilly country draining into it — an area nearly 600 times greater
than that of the loch. It is roughly quadrangular in outline, with a
maximum diameter of less than a quarter of a mile, and it covers an
area of about 13J acres, 80 per cent, of which is under less than 10 feet
of water. The deeper soundings were taken in the southern half of the
loch, the maximum depth observed being 17 feet. The volume of water
is estimated at 4 million cubic feet, and the mean depth at nearly
7 feet. Loch Crann was surveyed on August 19, 1902, when the level
was determined as being 513'7 feet above the sea. The temperature of
the surface water at 5 p.m. on that date was 59°*6 Fahr., and at a
depth of 14 feet 56°-2.

Loch a' Chroisg (see Plate LVIL). — Loch a' Chroisg (or Loch
Rosque) is^ne of the larger and more important lochs within the basin,
lying amid beautiful scenery, the hills on both sides rising to heights
exceeding 1500 feet, and culminating in Meall a' Chaoruinn (2313 feet)
on the northern shore (see Fig. 45). It is a good trout loch, and char
also occur, but the fishing is strictly preserved. The loch trends almost
due east and west, though very slightly sinuous in outline ; the shore-line
is on the whole very regular, except that two conspicuous alluvial cones
have been laid down on the northern shore at the mouths of the Allt
Duchairidh and neighbouring stream. The loch is 3J miles in length,
with a maximum breadth of nearly half a mile, the mean breadth being
over a quarter of a mile. Its waters cover an area of about 640 acres
(1 square mile), and it drains directly an area of over 1\ square miles,
but, as it receives the outflow from Loch Crann, its total drainage area
is over 19 square miles. The maximum depth of 168 feet was observed
approximately near the centre of the loch, opposite the mouth of the
Allt Duchairidh entering the loch on its northern shore, and about 2
miles from the east end. The volume of water contained in the loch is
estimated at 2057 million cubic feet, and the mean depth at nearly 74

average ; for August, 1901, the mean was 58°-7, or 2° above the average, while for August,
1902, the mean was 54°-2, or 2£° below the average. Sunshine records are available for
Strathpeffer within the Conon basin during1 these seasons, and they bear the same relations:
thus during July, 1901, 162-1 hours of sunshine were recorded at Strathpeffer (or 34-5 above
the normal for that month, and 30 per cent, of the possible amount), while during July,
1902, the duration of sunshine was 95-6 hours (or 32-0 below the normal, and 18 per cent, of
the possible amount) ; during August the difference was not so marked in the two years,
the duration in August, 1901, being 140-0 hours (or 18-5 above the normal, and 30 per cent,
of the possible amount), while in August, 1902, the duration was 131-8 hours (or 10-3 above
the normal, and 28 per cent, of the possible amount). The sunshine records for Inver-
ness agree closely with those given above for Strathpeffer for the two seasons under
consideration.

264

BATHYMETRICAL SURVEY OF

feet. The loch was surveyed on July 30 to August 1, 1902, and the
elevation of the lake-surface, on commencing the survey, was found, by
levelling from bench-mark, to be 508*4 feet above the level of the sea ;
when levelled by the Ordnance Survey officers on July 3, 1868, the
elevation was 507'9 feet above sea-level.

Loch a' Chroisg forms a simple basin with no pronounced irregu-
larities of the lake-floor, as is well shown by the longitudinal and
cross sections on the map; the contour-lines enclose continuous areas
following approximately the outline of the loch. The 100-feet basin

FIG. 45. LOCH A' CHROISG, LOOKING WEST.

(Photograph by Mr. T. N. Johnston, M.B., C.M., F.R.X.K.)

exceeds 2 miles, and the 50-feet basin is nearly 2| miles, in length,
approaching in each case rather nearer to the east than to the west end
of the loch, while the small 1 50-feet basin lies nearer to the west than
to the east end. The approximate areas between the consecutive
contour-lines drawn in at equal intervals, and the percentages to the
total area of the loch, are as follows : —

Oto 50 feet
50,, 100 „
100,, 150 „
Over 150 ,

241 acres
186 „
195 „

640 ,

37 '7 per cent.
29-0
30-5
2-8

100-0

The slightly larger area between 100 and 150 feet than between 50
and 100 feet indicates the flat-bottomed character of the deeper part

THE FRESH- WATER LOCHS OF SCOTLAND.

265

of the loch, and the soundings show in certain places rather steep slopes
both off the northern and southern shores.

Temperature Observations. — In the following table are given the
results of a series of temperatures taken in Loch a' Chroisg on August
22, 1901, by Mr. Clark, and of two series taken by the Lake Survey
staff on August 1, 1902: —

Depth in feet.

August 22, 1901
(R. M. Clark).

August 1, 1902.
i mile from E. end
of loch in 106 feet.

August 1, 1902.
Deepest part of loch
in 156 feet.

= Fahr.

Fahr.

a Fahr.

0

58-2

55-0

54O

20

58-2

tm

...

25

53-7

53-9

40

58-0

...

50

53-1

53-2

60

57'6

...

:•-.

f>3:3

51-0

80

51-9

53-2

90

50-5

100

48-5

49-9

49-1

120

47-5

...

150

48-9

The series taken in 1901 shows a range from surface to bottom
amounting to 10°*7, whereas the two series taken in 1902 show a range
of only 5° in each case, and an extreme range of 6°. The upper layers
of water down to a depth of 60 feet were much warmer in 1901 than in
1902, but between 60 and 100 feet the 1901 observations indicated a
fall of 9° (viz., a fall of 5°-7 between 60 and 80 feet, and a fall of 3°-4
between 80 and 100 feet), so that the temperature of the bottom layers
of water beyond 100 feet was lower in 1901 than was observed at these
depths in 1902.

Seiche. — On August 19, 1902, between 4.30 and 5.30 p.m., a seiche
was observed by Mr. James Murray within the shelter of the pier at the
east end of Loch a' Chroisg, a light west breeze blowing at the time. The
amplitude was a quarter of an inch, and the period about 11 \ minutes.

Loch Gown (see Plate LVII.). — Loch Gown (or Ledgowan) lies about
a mile to the south-east of Loch a' Chroisg, and is also a good trout loch,
but the fishing is preserved. It trends in a north-east and south-west
direction, is very irregular in outline, and about 1J miles in length.
Though it may at one time have formed a single lake, it is now divided
into two distinct lakes having, at the time of the survey, a difference
in level exceeding 2 feet. This separation has probably been brought
about mainly by the deposition of material laid down by the Allt
Mhartuin, and the passage between them is obstructed by weeds,
so that it is impossible to row a boat from one loch to the other, except
after heavy floods. The two lochs are nearly equal in superficial area,
but the southern basin is much deeper than the northern one.

266

BATHYMETRICAL SURVEY OP

South Loch Gown. — The southern loch is roughly quadrangular in
outline, over half a mile in length, and nearly a third of a mile in
maximum width, covering an area of about 55 acres, while it drains
an area exceeding 13 square miles. The maximum depth of 52 feet
was observed relatively close to the north-eastern shore. The volume
of water is estimated at 38 million cubic feet, and the mean depth at
nearly 16 feet. The loch forms a simple basin, the 10-feet contour
following approximately the outline of the loch and extending a short
distance into the passage leading to the northern loch, and the 25-feet
basin is centrally placed. Of the entire lake-floor, only 13 per cent, is
covered by more than 25 feet of water. It was surveyed on August 2,
1902, when the elevation was determined as being 524-4 feet above the
level of the sea.

North Loch Gown. — The northern loch is more oblong in outline
than the southern loch, so that while nearly equal in length its
maximum width is less, viz., about a fifth of a mile. Its waters cover
an area of about 48 acres, and it drains directly an area of about
1 square mile ; but, since it receives the outflow from the southern loch,
its total drainage area is over 14 square miles — nearly 200 times
greater than the area of the loch. The greatest depth observed was
17 feet, approximately near the centre of the loch. The volume of
water is estimated at 14 million cubic feet, and the mean depth at
nearly 7 feet. A constriction in the outline towards the southern end
of the loch is accompanied by a slight shoaling of the bottom, the
result being that a small 10-feet basin near the southern end, with
a maximum depth of 13 feet, is separated from the large main basin.
Of the entire lake-floor 22 per cent, is covered by more than 10 feet
of water. It was surveyed on the same day as the southern loch
(August 2, 1902), and the elevation was determined as being 522' 1
feet above sea-level.

Temperature Observations. — Serial temperatures were taken in the
deepest part of each loch, with the following results : —

North Loch Gown,

South Loch Gown,

Depth in feet.

August 2, 1902,

August 2, 1902,

1 p.m.

4 p.m.

0 Fahr.

0 Fahr.

Surface

557

55-0

10

557

55-0

15

55-7

20

55-0

30

53-8

40

...

52-1

In the shallow north loch the temperature was found to be constant
from surface to bottom, and in the south loch the temperature was
constant from the surface down to a depth of 20 feet (though more

THE FRKSH- WATER LOCHS OF SCOTLAND. 267

than half a degree lower than in the north loch); between 20 and
30 feet the fall was l°-2, and between 30 and 40 feet l°-7— a fall of
nearly 3° in the 20 feet of depth.

Loch Achanalt (see Plate LVIII.). — Loch Achanalt is an irregular
shallow loch apparently in process of being silted up, the material
brought down by the river Bran forming two long spits extending out
towards the centre of the loch. The northern spit extends nearly across
the loch, joining the islands, and leaving only a narrow passage close to
the eastern shore, through which there was a strong current, and thus
practically cutting the loch into two portions. The western shores
are bordered by weeds. It flows into Loch a' Chuiliiin by a short and
rapid stream, the difference in level exceeding 4 feet; the Highland
railway is carried over the passage between the two lochs. Loch
Achanalt is approximately quadrangular in outline, its maximum
diameter exceeding three-quarters of a mile, and it covers an area
of about 160 acres, or one-quarter of a square mile. The deepest water
was found comparatively close to the western shore, south of the
entrance of the river Bran, where two soundings of 9 feet and two
soundings of 8 feet were recorded. The volume of water is estimated
at 31 million cubic feet, and the mean depth at 4J feet — half the
maximum depth. The area draining directly into Loch Achanalt is
very large, exceeding 39 square miles ; but, since it receives the outflow
from Lochs a' Chroisg and Gown, its total drainage area exceeds
72J square miles, or 290 times the area of the loch. Loch Achanalt
was surveyed on August 9, 1902, when the elevation of the lake-
surface was found to be 365*1 feet above the sea; when levelled by
the Ordnance Survey officers on May 9, 1870, the elevation was 364-7
feet above sea-level. The temperature of the surface water on the date
of the survey was 57°'l Fahr. ; the temperature of the river Bran being
55°-2. On August 19, 1901, Mr. Clark observed a temperature of 60°'l
at the surface, and a temperature of 60°-4 at a depth of 5 feet.

Loch a' Chuilinn (see Plate LVIII.). — Loch a' Chuilinn (or Culen)
trends east and west, is irregular in outline, of varying width, and with
an undulating floor. It is 1 J miles in length, with a maximum breadth
of one -third of a mile. Its waters cover an area of about 113 acres, and
it drains directly an area of nearly 1J square miles; but as it receives
the outflow from Loch Achanalt, its total drainage area is over 74
square miles — over 400 times the area of the loch. The maximum
depth of 43 feet was observed approximately near the middle of the
loch. The volume of water is estimated at 50 million cubic feet and
the mean depth at 10J feet. The bottom of Loch a' Chuilinn is most
irregular; close to the west end is a 10-feet basin, with a maximum
depth of 29 feet, the slopes of which are in places steep, depths of 20

268

BATHYMETRICAL SURVEY OF

and 21 feet having been found close inshore. Separated from this
western basin by an interval of about 600 yards, in which the depth
does not exceed 8 feet, lies the central 10 -feet basin, enclosing the
maximum depth of the loch (43 feet), and here again the slope is steep,
one sounding of 29 feet being recorded close to the southern shore.
Separated from this central basin by a short interval, 7 feet in depth,
is a small eastern basin, with a maximum depth of 29 feet, and after
another shallow interval the water deepens at the exit of the outflowing
river, where soundings of 13 feet were taken. Of the entire lake-
floor, 75 acres (or 67 per cent.) are covered by less than 10 feet of
water, and 7 acres (or 6 per cent.) by more than 25 feet of water.
The loch was surveyed on August 11, 1902, when the elevation of the
lake-surface was found to be 360'8 feet above the sea.

Temperature Observations. — The following table gives the results of
observations taken in Loch a' Chuflinn by Mr. Clark on August 19,
1901, and by the Lake Survey on August 11, 1902: —

Depth in feet.

Aug\ist 19, 1901
(R. M. Clark).

August 11, 1902.

0 Fahr.

0 Fahr.

0

60-3

557

5

60-0

10

59-6

15

55-4

20

59-6

30

...

54:7

40

58-6

...

These observations show that the whole body of water was much
warmer in 1901 than at the same season in 1902, the difference amount-
ing on the average to about 4° ; the range of temperature was in each
case small.

Loch Fannich (see Plate LIX.). — Loch Fannich is the largest within
the Cromarty firth drainage-basin, and is surpassed in depth only by
Loch Glass. It is situated in Fannich deer forest amid splendid scenery
(see Fig. 46), the mountains along the northern shore rising to heights
exceeding 3000 feet, including An Coileachan (3015 feet), Meallan
Rairigidh (3109), Sgurr Mor (3637), Sgurr nan Clach Geala (3500),
Sgurr Breac (3000), and a' Chailleach (3276). The trout fishing is
good, the fish being of fair size, but the loch is strictly preserved.
The general trend of the loch is east and west, but the two ends have
a tendency to bend slightly to the northwards. Loch Fannich is nearly
7 miles in length, the maximum breadth exceeding three-quarters of a
mile, and the mean breadth is over half a mile. Its waters cover an area
of 2300 acres (or over 3J square miles), and it drains an area ten times

THE FRESH-WATER LOCHS OF SCOTLAND. 269

greater (over 35 \ square miles). The maximum depth of 282 feet was
observed about 1J miles from the east end, and about 5J miles from the
west end. The volume of water is estimated at 10,920 millions of cubic
feet, and the mean depth at nearly 109 feet. Loch Fannich forms a
simple basin, all the contour-lines enclosing continuous areas, though
the deepest part (exceeding 200 feet in depth) lies in the eastern
half of the loch. The 50-feet area extends from end to end, coinciding
approximately with the outline of the loch. The 100-feet area
approaches to within half a mile from both ends, and is nearly 6 miles
in length ; there is a slight shoaling of the water opposite Rudha Mor

FIG. 46. LOCH FANNICH, LOOKING EAST.

(Photoyraph by Mr. T. N. Johnson. M.B., C.M., F.R.S.E.)

to 103 feet, with deeper water to the east and west. The 1 50-feet area
is distant over 2J miles from the west end, and is over 3£ miles in
length. The 200-feet area is 2| miles, and the 250-feet area If miles,
in length, and they approach to within three-quarters of a mile from
the east end. The slight shoaling opposite Rudha Mor has already been
referred to, and a similar shoaling is observable within the 200-feet
contour opposite Fannich Lodge, where the depth decreases from 226
feet to 212 feet, and increases again on proceeding eastwards into the
250-feet area ; these two shoalings are indicated in the longitudinal
section A-B on the map. A sinuosity is also seen in the 200-feet contour
off the southern shore, opposite Fannich Lodge, due to the shoaling of
the water from 202 to 191 feet, but on the whole the lake-floor may
be said to be extremely regular in conformation. The cross section

270

BATHYMETRICAL SURVEY OF

C-D is taken across the loch in the position of the deepest sounding.
The areas between the consecutive contour-lines drawn in at equal
intervals, and the percentages to the total area of the loch, are as
follows : —

0 to 50 feet 658 acres 28-6 per cent.

50,, 100
100 „ 150
150,, 200
200,, 250
Over 250

582
418
272
220
155

2305

25-2

18-1

11-8

9-6

6-7

100-0

The regularity of the average slope of the bottom is indicated by
the gradually decreasing areas between the contour-lines, and the
comparatively large area within the deepest contour indicates the
flat-bottomed character of the deeper part of the loch.

Loch Fannich was surveyed on August 13 and 14, 1902, and the
elevation of the lake-surface was found, on commencing the survey, to
be 821 '9 feet above sea-level, which is identical with the level observed
by the Ordnance Survey on May 27, 1870.

Temperature Observations. — The temperature of the surface water
during the two days spent on the survey varied from 52°'7 Fahr. to
58001. Two serial temperatures were taken on August 14, 1902, with
the following results : —

Depth in feet.

August 14, 1902,
4-1.5 p.m.
Deepest part of loch.

August 14, 1902,
5-30 p.m.
South-east Of Rudha
Mor.

Fahr.

0 Fahr.

Surface

53-0

54-0

5

52-0

...

10

51-9

20

51-6

53-0

40

52-5

50

51'0

70

50:0

100

48 '-6

467

130

...

457

150

45-6

200

44-9

...

250

44-5

281

44-4

...

Each of these series shows a range from surface to bottom of about
8J°. The temperature was higher in the upper 40 feet of water towards
the west end of the loch than in the deep water towards the east end,
but at the depth of 100 feet the temperature was 2° lower in the former
position. Off Rudha Mor there was a fall of 2°-5 between 40 and 70
feet, and a further fall of 3°«3 between 70 and 100 feet (equal to 5°'8 in

. THE FRESH-WATER LOCHS OF SCOTLAND. 271

the 60 feet of water), while in the deepest part there was a fall of 2°-4
between 50 and 100 feet, and a further fall of 3° between 100 and 150
feet (equal to 5° -4 in the 100 feet of water). All the observations
indicate a range of temperature throughout the entire body of water
amounting to 13°*7.

Loch Luichart (see Plate LX.). — Loch Luichart is another large and
important loch within the Cromarty firth drainage basin, second as

FIG. 47. LOCH LUICHART, LOOKING ACROSS THE HEAD OF THE LAKE.

(Photograph by Mr. David Brigham.)

regards length only to Loch Fannich, though slightly inferior as regards
superficial area to Loch Glass. It is a good fishing loch situated amid
grand scenery, where Strath Bran bends to the south-east to join Strath
Conon (see Fig. 47). Its general trend is north-west and south-east,
bending round the base of Sgiirr Mairc-suidhe, and it is broadest at the
north-west end, narrowing towards the south-east. It is 5 miles in
length, with a maximum breadth of nearly a mile, the mean width being
one-third of a mile. Its waters cover an area of about 1130 acres, or
1J square miles, and it drains directly an area of about 39 \ square miles,

272 BATHYMETRICAL SURVEY OF

but since it receives the outflow from all the lochs described in the
preceding pages, its total drainage area is very large — about 149J
square miles, an area 85 times greater than the area of the loch. The
maximum depth of 164 feet was observed about 1J miles, or about
one-third of the length of the loch, from the north-west end. The
volume of water is estimated at 3288 millions of cubic feet, and the
mean depth at nearly 67 feet. The loch was surveyed on August 16,
1902, when the elevation of the lake-surface was found to be 249-8 feet
above the sea.

The floor of Loch Luichart is irregular, there being three 50-feet
basins separated by shallower water. The largest and deepest lies in the
wider north-western half of the loch, and is about 2J miles in length,
approaching to within less than 200 yards from that end. The central
50-feet basin is separated from the north-western basin by an interval of
half a mile, in which lies the single small island in the loch, and where
the depth in the centre at another place is only 5 feet, and is over 1J
miles in length. Immediately to the south-east of this central basin
there is a narrow constriction in the outline of the loch, in which a
depth of 16 feet was recorded, succeeded by a slight expansion contain-
ing the third 50-feet basin, with a maximum depth of 55 feet and of
small extent. The principal 100-feet basin in the north-western part
of the loch is nearly 2 miles in length, and encloses the deepest part of
the loch. Two small subsidiary 100-feet basins lie within the central
50-feet basin : one based upon an isolated sounding of 100 feet, the
other near the south-eastern end having a maximum depth of 115 feet.
The 150-feet basin is nearly a mile in length, and is distant three-
quarters of a mile from the north-west end of the loch ; the maximum
depth of 164 feet was recorded near the south-eastern end of the basin.
It is curious to note the difference in the outline of this 150-feet basin
as compared with the outlines of the 50 and 100-feet basins enclosing
it, for, while the shallower contours follow approximately the shore-
line, and therefore enclose areas widest towards the north-west and
narrowing gradually in the opposite direction, the 150-feet basin is
widest towards the south-east and narrows gradually to the north-west
as the outline of the loch widens out. At the same time the deep basin
approaches nearer to the northern shore at its north-west end, while it
approaches nearer to the southern shore at the opposite deeper end, so
that at the position of the deepest sounding the slope off the southern
shore is much steeper than off the northern shore, as is well brought out
in the cross-section C-D 011 the map. The longitudinal section A-B
down the centre of the loch shows the three basins included in the loch,
each successively deeper on proceeding towards the north-west end.
The areas between the consecutive contour-lines, and the percentages
to the total area of the loch, are as follows : —

THE FRESH-WATER LOCHS OF SCOTLAND.

273

Oto 50 feet
50,, 100 „
100,, 150 „
Over 150 ,

482 acres
385 „
208 „
54 „

1129 ,

42 '7 per cent.
34-1 „
18-4
4-8

100-0

Temperature Observations. — The following table gives the results of
observations taken in Loch Luichart by Mr. Clark on August 25, 1901,
and by the Lake Survey on August 16, 1902 : —

Depth in feet,

August 25. 1901
(B. M. Clark).

August 16, 1902,
5 p.m.
Deepest part of loch
in 152 feet.

August 16, 1902,
6p.m.
Near N.W. end in
93 feet.

°Fahr.

0 Fahr.

°Fahr.

0

60-6

55-9

56-0

10

60-0

...

20

59-6

55:8

...

40

59-1

-

50

_

54:8

56-0

60

57:2

...

70

•

56-0

75

...

5 1-6

...

80

50-9

90

...

...

48:5

100

50-5

48-4

150

48-0

The range of temperature shown by the 1901 observations amounts
to 10°, while that shown by the 1902 observations amounts to 8°. The
temperature of the upper 60 feet of water was higher in 1901 than was
observed in 1902, as was also the case at a depth of 100 feet, but a
lower reading was recorded at 80 feet in 1901 than at 70 and 75 feet in
1902. The two serials taken in 1902 show the effect of the strong wind
which was blowing up the loch at the time of the survey, the maximum
temperature observed extending down to a depth of 70 feet near the
head of the loch, whereas 1J miles further down the loch the temperature
was always lower, amounting to a difference of l°-2 at 50 feet and 40<4
at 70 feet, beyond which depth a much larger fall of temperature was
observed towards the head of the loch than was recorded farther down
(equal to a fall of 7°'5 in the interval of 20 feet between 70 and 90 feet
in the former case, and a fall of 3°-2 in the interval of 25 feet between
75 and 100 feet in the latter case).

Loch Beannaclian (see Plate LVIIL). — Loch Beannachan (or Ben-
nachran) is situated at the head of Strath Conon, amid wild moorland
scenery. It trends in a west-north-west and east-south-east direction,

T

274

BATHYMETRICAL SURVEY OF

narrowing towards the eastern end. It is over If miles in length, with
a maximum breadth of one-third of a mile, the mean breadth being a
quarter of a mile. Its waters cover an area of 267 acres, or nearly half
a square mile, and it drains an area 72 times greater — an area exceed-
ing 30 square miles. The maximum depth of 176 feet was observed
approximately near the centre of the loch. The volume of water is
estimated at 819 million cubic feet, and the mean depth at 70 J feet.
The loch was surveyed on August 22, 1902, when the elevation of the
lake-surface was found to be 465-6 feet above sea-level; when visited
by the officers of the Ordnance Survey on June 6, 1870, the elevation
was 465' 1 feet above the sea.

Loch Beannachan forms a simple basin, the contour-lines following
approximately the outline of the loch, but approaching in each case
nearer to the western than to the eastern end. There is a large wooded
island at the entrance of the inflowing river at the west end, and a
small island near the exit of the outflowing river at the opposite end.
The slope offshore is in some places very steep, especially at certain
points along the southern shore, and at the position of the deepest
sounding the slope is steeper off the southern than off the northern
shore, as is shown in the cross section C-D on the map. The longi-
tudinal section A-B shows the gradual slope towards the two ends,
with quite a flat-bottomed character in the deeper water, which is also
indicated by the larger area between 100 and 150 feet than between
50 and 100 feet, as given in the following table: —

0 to 50 feet
50,, 100 „
100 „ 150 „
Over 150 ,

113 acres
67 „
72 „
15 „

267

42-3 per cent.
25-0

27 '2
5 '5

100-0

Temperature Observations. — A series of temperatures taken in the
deepest part of the loch at 4.15 p.m. on August 22, 1902, gave the
following results : —

Surface

10 feet

20

30

40

50

60

75
100
170

55°'OFahr.
55° -0
54° -8
53° -0
52° -9
52° -0
50° -5
46° -9
46° -1
46° -0

THE FRESH- WATER LOCHS OF SCOTLAND. 275

This series shows a range of temperature from surface to bottom
amounting to 9° Fahr. The upper 20 feet of water was practically of
uniform temperature, followed by a fall of l°-8 between 20 and 30 feet,
but the greatest fall observed was one of 30<6 between 60 and 75 feet.

Loch Achilty (see Plate LXL). — Loch Achilty is a small but deep
loch in Torrachilty wood, near Strathpeffer, containing char. In outline
it is somewhat elliptical, with the long axis trending north-east and
south-west. It is about 1500 yards in length, by 700 yards in maxi-
mum breadth, the mean breadth being 450 yards. Its waters cover an
area of about 147 acres (or nearly a quarter of a square mile), and it
drains an area exceeding 2 square miles. The maximum depth of
119 feet was observed about 250 yards from the western shore. The
volume of water is estimated at 332 million cubic feet, and the mean
depth at 51 J feet. The floor of Loch Achilty is irregular. The 10-feet
contour follows approximately the outline of the loch, in many places
approaching very close to the shore, but the deeper contours are all
sinuous in character, and there are two small basins exceeding 100 feet
in depth, the larger and deeper towards the western shore, and the
smaller, based on a sounding of 112 feet, near the centre of the loch.
Deep soundings were recorded in some positions near shore, while in
other positions comparatively shallow soundings were taken some
distance offshore. A longitudinal section along the axis of maximum
depth is shown in section C-D on the map. The areas between the
consecutive contour-lines, and the percentages to the total area of the
loch, are as follows : —

0 to 25 feet 41 acres 28-0 per cent.

25,, 50 „ 28 „ 19-2 „

50,, 75 „ 39 „ 26-2 „

75,, 100 „ 30 „ 20-2 „
Over 100 „ 9 ,, 6*4 ,,

147 , 100-0

This table shows a smaller area, and therefore an average steeper
slope, between 25 and 50 feet, than in the deeper water. The loch was
surveyed on August 20 and 21, 1902, when the elevation of the lake-
surface was found to be 98'5 feet above the sea, so that the 100-feet
contours show approximately the two small portions of the lake-floor
which lie below the level of the sea.

Temperature Observations. — In the following table are given the
results of three series of temperatures taken in Loch Achilty by Mr.
Clark in 1901, along with a series taken in 1902 at the time of the
survey : —

276

BATHYMETRICAL SURVEY OF

Depth in

feet.

August 11, 1901
(B. M. Clark).

August 23, 1901
(R. M. Clark).

September 2, 1901
(R. M. Clark).

August 21, 1902
(Lake Survey).

0

0 Fahr.

63-5

0 Fahr.
61-9

0 Fahr.

0 Fahr.
58-4

5

...

61-9

t

10

62:0

.

58:1

20

61 -5

.

57-6

25

59 :4

57-3

56-0

30

52-0

t

54-9

35

46-0

50-9

40

460

44-0

45 -9

48-0

50

43-2

43-2

46-0

55

42-8

42-8

60

42-8

42-8

...

70

42-3

100

* . .

. . .

44!9

These serials indicate a most remarkable range of temperature — a
range amounting to 21°-2 from the surface to a depth of 70 feet on
August 11, 1901, and 190tl from the surface to a depth of 60 feet on
August 23, 1901 ; the range observed in 1902 was much less, viz., 13°'5
from the surface to a depth of 100 feet. Down to a depth of 25 feet the
readings were higher in 1901 than in 1902, but beyond that depth the
temperature was lower in 1901 than in 1902. The greatest fall of
temperature was observed between the depths of 25 and 40 feet in both
seasons, but the decrease of temperature within this interval of 15 feet
amounted in 1901 to 13°-3 and 13°-4, while in 1902 it amounted only to
8°. The only observations that may be compared, as regards range
of temperature, with these in Loch Achilty, were taken in Loch Mon-
zievaird* in the Tay basin on June 8, 1903, when the range amounted
to 200< 6 from the surface to a depth of 36 feet, and when a fall of
temperature equal to l°-5 per foot of depth was'observed between 5 and
15 feet. The temperature conditions observed in Loch Achilty (as well
as in Loch Monzievaird) may probably be ascribed to — (1) the com-
paratively great depth, (2) the comparatively small drainage area,
and (3) the sheltered position, the thickly wooded shores tending to
temper the force of the winds blowing across the surface of the water.
Mention may here be made also of the large range of temperature
observed in the little Loch Dubhf in the nan Uamh basin on July 12,
1902, when the range amounted to 15|° from the surface to a depth of
100 feet ; it is possible that under favourable weather conditions, and
later in the season, the range of temperature in the waters of Loch Dubh
may equal that observed in Loch Achilty.

* See p. 120.

f See p. 255.

THE FRESH-WATER LOCHS OF SCOTLAND. 277

Loch Garve (see Plate LXL). — Loch Garve lies about 5 miles to the
west of Strathpeffer, and to the south-west of the mighty Ben Wyvis
(3295 feet). It receives the drainage from a large tract of mountainous
country lying to the north and north-west. The body of the loch
trends in a north-west and south-east direction, and is somewhat
elliptical in outline, while the south-eastern end takes a slight bend
to the north-east. The loch is over 1| miles in extreme length, with
a maximum breadth of .half a mile, the mean breadth being over
one-third of a mile. Its waters cover an area of about 380 acres, or
over half a square mile, and it drains an area of 114 square miles — an
area nearly 200 times greater than that of the loch. The maximum
depth of 105 feet was observed near the centre of the loch, but
towards the south-western shore. The volume of water is estimated
at 721 million cubic feet, and the mean depth at 43 J feet. The loch
forms on the whole a simple basin, with a slight shoaling at the
position of the bend in the outline of the loch. The 10-feet and 25-feet
contours extend from end to end of the loch, following approximately
the form of the shore-line ; but the deeper contours are confined to
the wide body of the loch, the 50-feet basin being nearly a mile, and
the 100-feet basin nearly a quarter of a mile, in length. Off the
central portions of both the north-eastern and south-western shores
the slope is moderately steep. The longitudinal section A-B on the
map is taken along the axis of maximum depth, and shows the slight
deepening of the water near the south-eastern end. The areas between
the consecutive contour-lines, and the percentages to the total area
of the loch, are as follows : —

0 to 25 feet 131 acres 34 '5 per cent.

25,, 50 „ 104 „ 27-4 „

50,, 75 „ 72 „ 18-8 „

75,, 100 „ 64 „ 16-9 „

Over 100 , 9 , 2-4

380 , 100-0

From this table it will be seen that nearly two-thirds of the entire
lake-floor is covered by less than 50 feet of water. Loch Garve was
surveyed on August 15, 1902, when the elevation of the lake-surface
was found to be 218-8 feet above the sea ; when visited by the Ordnanc-3
Survey officers on August 15, 1871, the elevation was 219*6 feet above
sea-level.

Temperature Observations. — The following table gives the results of
observations made in Loch Garve in 1901 by Mr. Clark, and in 1902
by the Lake Survey : —

278

BATHYMETRICAL SURVEY OF

Depth in feet.

August 18, 1901
(R. M. Clark).

August 15, 1902.

0 Fahr.

0 Fahr.

0

59-3

54-2

5

59-3

10

59-3

54:2

15

59-2

...

20

59-2

30

...

54:2

40

59-0

50

54-0

55

55-4

60

54-2

...

70 '

51 -0

53:5

85

49-0

The 1901 observations show a range exceeding 10°, whereas the 1902
observations show that the temperature was practically uniform from
surface to bottom, which may perhaps be ascribed to the influence
of the strong winds prevailing at the time of the survey, causing a
thorough circulation in the whole body of water.

Loch Kinellan (see Plate LXL). — Loch Kinellan is a small shallow
loch near Strathpeffer, which was surveyed on August 23, 1902. The
elevation of the lake-surface was not determined by levelling, but
from the Ordnance Survey contours it is evidently nearly 500 feet
above the sea. It trends north-east and south-west, widest in the
south-western portion, and with a large wooded island near the centre.
Weeds abound along the western and south-western shores, and also
between the island and the eastern shore. It is one-third of a mile
in length, and its waters cover an area of about 15 acres. Soundings
of 10 and 11 feet were taken to the north-east of the island, but the
deepest part lies to the south-west, the maximum depth of 16 feet
having been observed about midway between the island and the
southern shore; 73 per cent, of the lake-floor is covered by less than
10 feet of water. The volume of water is estimated at 5 million cubic
feet, and the mean depth at over 7 feet. The temperature of the
surface water at 12.30 p.m. on the date of the survey was 58°-7
Fahr., and at a depth of 14 feet 58°'3.

Loch Ussie (see Plate LXI.). — Loch Ussie (or Usie) is about a mile
from Strathpeffer and 3 miles from Dingwall. It is irregular and
subcircular in outline, with a maximum diameter from north-east to
south-west of nearly a mile. There is one large island with a heronry
upon it, and several smaller ones, and weeds are abundant in some
of the bays and in the vicinity of the islands. It was surveyed on
August 29, 1902, but the elevation above the sea was not determined

THE FRESH- WATER LOCHS OF SCOTLAND. 279

by levelling; when visited by the Ordnance Survey officers on Sep-
tember 7, 1870, the elevation was 418'9 feet above sea-level. Its waters
cover an area of nearly 200 acres, or less than one-third of a square
mile, and it drains an area of nearly 4 square miles. The loch is on
the whole very shallow, with a deep hole in the north-eastern part of
the loch, in which two soundings of 35 feet were taken; except for a
neighbouring sounding of 22 feet, the remainder of the lake-floor is
covered by less than 20 feet of water, and all the western and southern
parts of the loch are less than 10 feet in depth. The volume of water
is estimated at 68 million cubic feet, and the mean depth at 8 feet.
Only 22 per cent, of the lake-bottom is covered by more than 10 feet
of water, and only 2 per cent, by more than 25 feet of water. At
5.15 p.m. on the date of the survey the surface temperature was 59°'3
Fahr., and a reading at 27 feet gave 59°-0.

Loch Glass (see Plate LXIL). — Loch Glass is one of the larger and
more important lochs within the drainage basin of the Cromarty firth,
and it exceeds in depth all the other lochs of the basin. It lies in a
mountainous district to the north of Strathpeffer, with Ben Wyvis and
other peaks exceeding 3000 feet in height to the south-west, and lesser
mountains to west, north, and north-east. It trends in a north-west
and south-east direction, but with a slight bend in the outline, causing
it to appear somewhat crescent-shaped. It is 4 miles in length, with a
maximum width near the centre of two-thirds of a mile, narrowing
gradually towards the south-east end, where the river Glass flows out,
the mean breadth being nearly half a mile. Its waters cover an area of
nearly 2 square miles, and it drains an area exceeding 25 square miles.
The maximum depth of 365 feet was observed nearer the north-west
than the south-east end, and towards the north-eastern shore. The
volume of water is estimated at 8265 millions of cubic feet, and the
mean depth at 159 feet. It was surveyed on August 26 and 27, 1902,
but the elevation of the lake-surface above the sea was not determined
by levelling ; when visited by the Ordnance Survey officers on September
1, 1868, the elevation was found to be 712*9 feet above sea-level.

Loch Glass forms a simple basin, with very few minor undulations
of the lake-floor. The deeper water lies towards the north-west end,
and the contour-lines all enclose continuous areas. The 100-feet basin
is 2 1 miles in length, approaching close to the north-west end, but
distant nearly a mile from the south-east end. The 200-feet basin
is nearly 2 miles, and the 300-feet basin over a mile, in length, being
distant respectively 1| and 2 miles from the south-east end. The
soundings indicate here and there slight irregularities on the lake-floor,
and sometimes in very deep water. One of these gives rise to a curious
sinuosity in the 300-feet contour-line off the south-western shore, and
the sounding immediately to the south-west of the maximum depth of

280 BATHYMETRICAL SURVEY OF

365 feet indicates a shoaling of the water to 346 feet, followed by a
deepening of the water to 354 feet, which is well brought out in the
cross section C-D on the map. The longitudinal section A-B shows the
rapid deepening of the water on proceeding from the north-west end,
and the gradual shoaling of the water on approaching the opposite end
of the loch. The areas between the consecutive contour-lines, and the
percentages to the total area of the loch, are as follows : —

0 to 100 feet 454 acres 38 '1 per cent.

100,, 200 „ 309 „ 25-8

200,, 300 ,, 269 „ 22-6

Over 300 , 161 13'5

1193 „ 100-0

The comparatively large area of the lake-floor covered by more than
300 feet of water indicates the flat-bottomed character of the deeper
part of the loch, and this is also shown by the comparatively great
width of the 200-feet and 300-feet basins, and is well seen in the cross
section C-D.

Temperature Observations. — An interesting series of temperatures
was taken in the deepest part of Loch Glass at 6 p.m. on August 27,
1902, as given in the following table: —

Surface 54C'7 Fahr.

50 feet 51°-7 „

100 „ 46°-2 „

150 „ 43°'5 „

250 „ 42°-5 „

350 „ ... 42°-3 „

This series shows a range of temperature from surface to bottom
amounting to 12°-4, the greatest fall being one of 50>5 between 50 and
100 feet. The temperatures taken in Loch Achilty six days earlier gave
a higher temperature from the surface down to 30 feet than was
observed at the surface of Loch Glass, but a lower temperature at 50
and 100 feet, the differences being respectively 5°-7 and l°-3.

Loch Morie (see Plate LXIII.). — Loch Morie (or Muilie) lies less
than 2 miles to the north of Loch Glass, with the crests of Meall Beag
(2121 feet) and Meall Mor (2419 feet) rising between them. It is an
important and deep loch, containing trout, but the fishing is preserved.
Lochs a' Chaoruinn and Loch Magharaidh, which flow into it, could
not be sounded for lack of boats. It trends in a north-west and south-
east direction, with a slight sinuosity in its outline. It is 2J miles
in length, with a maximum breadth of over half a mile. Its waters
cover an area of nearly a square mile, and it receives the drainage from
a large tract of the mountainous country to the north-west, the area

THE FRESH- WATER LOCHS OF SCOTLAND. 281

of which exceeds 35 square miles. The maximum depth of 270 feet
was observed in the central part of the loch, but nearer the south-
western than the north-eastern shore, as will be seen in the cross section
C-D on the map, which is taken at the position of the deepest sounding.
The volume of water is estimated at 3201 millions of cubic feet, and the
mean depth at 125 feet. Loch Morie was surveyed on August 28, 1902,
when the water-surface was found to be 621-6 feet above the sea; when
visited by the Ordnance Survey officers on September 28, 1868, the
elevation was 622 feet. The loch forms a simple basin, the contour-
lines all enclosing continuous areas. The shallower contours follow
approximately the outline of the loch, but the deeper ones bend in their
central portions towards the south-western shore. The 100-feet basin
is over 1J miles, and the 200-feet basin is over a mile, in length. The
slope of the bottom is in some places very steep — for instance, off the
south-western shore towards the north-west end, where a sounding
of 75 feet was taken about 60 feet from shore, and one of 124 feet about
120 feet from shore, showing in each case a gradient exceeding 1 in 1.
The areas between the consecutive contour-lines, and the percentages to
the total area of the loch, are as follows : —

Oto 50 feet 148 acres 25 -2 per cent.

50,, 100 „ 92 „ 15-8

100,, 150 „ 104 „ 17-7

150,, 200 „ 113 „ 19-2

200,, 250 „ 106 „ 18-0

Over 250 , 24 , 4-1

587 „ 100-0

It will be observed that the area between 50 and 100 feet, and to a
less extent that between 100 and 150 feet, are smaller than the
shallower and deeper zones, indicating an average slope steeper between
50 and 150 feet than elsewhere. The temperature of the surface water
was 54°-0 Fahr. on the date of the survey, but serial temperatures could
not be attempted on account of the gale that was blowing.

Luck Eye (see Plate LXIV.). — Loch Eye is a rather large but very
shallow loch, about 3 miles from Tain and a mile from Inver bay, an
inlet of the Dornoch firth. It was surveyed on September 26, 1902,
when the surface of the water was found to stand 47-8 feet above the
sea; on December 24, 1867, the Ordnance Survey officers found the
elevation to be 50*7 feet above sea-level, or 3 feet higher than in 1902.
The loch is 1J miles in length, with a maximum width of nearly two-
thirds of a mile, and covers an area of over 210 acres, or one-third
of a square mile. The maximum depth is 7 feet, and the mean depth
4 feet, the volume of water being estimated at 37 million cubic feet.

282

BATHYMETRICAL SURVEY OF

Ratio to
area of
loch.

all

li'S

t— ^H>OO5W'-H QOlT—

3 £8

8§1

a~<£

*!l

tr^* GO ^ ^ O* O1 00 Oi C^ ^^ *O 'OC

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IT"* ^ QO CC 00 O^> CC Oi CC CC OC T^ 'C CC OS ^H
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13

So S P S S w S S w P o c5 S 5

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09 1** Oft CO 64 ^1 «P A

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0000000000000000

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OJ t^* i?t t^* "^ ^ ^ *C JO tr^~ "^ cc "^ CC O

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00 6^

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THE FRESH- WATER LOCHS OF SCOTLAND. 283

The loch is a flat-bottomed shallow basin, 45 per cent, of the lake-floor
being covered by more than 5 feet of water. The temperature of the
surface water on the date of the survey was 54°-8 Fahr., while a
reading at the bottom in 7 feet gave 55°*0.

The particulars regarding the lochs in the Conon basin are collected
together in the table on p. 282 for convenience of reference and com-
parison. From this table it will be seen that in the sixteen lochs under
consideration, which cover an area of over 11 J square miles, nearly
2200 soundings were taken, or an average of 188 soundings per square
mile of surface. The aggregate volume of water contained in the
lochs is estimated at nearly 30,000 millions of cubic feet, and the
area draining into them is over 366 square miles, or 31J times the area
of the lochs.

NOTES ON THE GEOLOGY OF THE CONON BASIN.
By B. N. PEACH, LL.D., F.R.S., and J. HORNE, LL.D., F.R.S.

The rock groups entering into the geological structure of the Conon
basin and the area including Strath Glass and Strath Rusdale, north
of Ben Wyvis, belong to the crystalline schists and the Old Red
Sandstone. A line drawn from a point in Strath Rusdale above Ardross
Castle, south-west by Eileneach in Strath Glass, Achterneed station,
the Falls of Rogie, and across the Conon to Glen Orrin above Muirtown
House, roughly marks the boundary between the metamorphic rocks to
the west and the Old Red Sandstone bordering the Cromarty firth.
It will thus be seen that the crystalline schists form not only the greater
part of the basin, but also the highest and wildest territory.

From the researches of the Geological Survey, extending over the
greater portion of the area under description, it would appear that the
metamorphic rocks may be arranged in two divisions : (1) a group of
acid, basic, and ultrabasic rocks, resembling certain types of Lewisian
gneiss of pre-Torridonian age along the western seaboard of Sutherland
and Ross; (2) the Moine series, representing altered sediments and
including the main subdivisions, (a) granulitic quartz-schists or quartz
biotite granulites, (b) flaky muscovite biotite schists or gneiss frequently
garnetiferous, and passing into flaggy mica-schists (pelitic schists).

Though the group of rocks of Lewisian type comprises certain acid
granulitic gneisses that closely resemble the quartzose members of the
Moine series, yet their dominant feature is the alternation of acid and
basic materials in the form of biotite and hornblende gneisses. With

284 BATHYMETRICAL SURVEY OP

these are associated bands of garnet, amphibolite, and hornblende
schist that have been mapped for some distance both in the Fannich
mountains and near Scardroy, in the basin of the Meig. In some areas
schists of the ultra-basic type appear that represent original masses of
peridotite. This group forms isolated areas or inliers in the midst
of the Moine series, being regarded as older than the latter, and
probably representing the floor or platform on which the members of
the Moine series rest. It is significant that different bands of the
so-called Lewisian gneisses in the Conon basin are in contact with the
crystalline Moine schists of sedimentary origin, and that different
subdivisions of the latter overlap the former.

These gneisses of Lewisian type appear at intervals, sometimes
forming comparatively narrow zones, and, again, rather broad belts.
On the north and west slopes of the Fannich mountains they have been
traced for several miles, being there overlain and underlain by the
flaky muscovite biotite schists of the Moine series. Southwards between
Strath Bran and the basin of the Meig, near Scardroy, there is a large
development of them, where their relations to the Moine schists are
well displayed. They likewise appear in Glen Orrin, and southwards
towards Glen Strathfarrar, and eastwards near Loch Luichart.

With the exception of certain masses of foliated and unfoliated,
intrusive, igneous rocks, the members of the Moine series occupy the
rest of the area covered by the crystalline schists. Their lithological
characters are comparatively uniform. The two main subdivisions,
already indicated, graduate into each other in certain localities, thus
forming an intermediate type between the highly quartzose granulitic
schists on the one hand and the flaky muscovite biotite schists on the
other. The members of the Moine series, which have the largest
development and the widest distribution, consist of granulitic quartz-
schists or quartz biotite granulites, but the pelitic schists sometimes
form the most elevated ground, as, for instance, on Sgurr Mor Fannich
(3637 feet), the highest of the Fannich mountains.* The boundary line
between the two main subdivisions of the Moine series is highly involved,
showing intricate rapid folding, frequently isoclinal, and pointing to
intense reduplication of the strata. The most prominent belts of the
garnetiferous muscovite schists have a wide distribution in the basin of
the Conon. For example, they appear in the Fannich mountains, and
extend south-west by Ben Fionn and Loch Rosque to Moruisg, east of
Glen Carron. They likewise appear in Glen Orrin and Glen Meig,
and prominent bands have been traced more or less continuously from
Strath Bran north-north-west by Aultguish and the hills west of Strath
Vaich to Glen Beg and Glen Alladale, in the basin of Strath Carron.

* The quartz-schists contain pebbly bands in places, thus clearly showing their
derivative origin.

THE FRESH- WATER LOCHS OF SCOTLAND. 285

Still further east, this characteristic zone has been followed from Ben
Wyvis across Strath Glass and Strath Rusdale to the hills near Fearn.

The constant reappearance, throughout the metamorphic area of the
Conon basin, of the two main subdivisions of the Moine series suggests
the repetition of these zones by folding. Indeed, such is the view
adopted by the Geological Survey, and hence the actual thickness of
this series may be much more limited than the persistent dip of the
strata in one direction would lead us to suppose. The researches of the
Survey indicate a probable order of succession in these schists which
obtains in the tract between Ben Wyvis and Ben Dearg, and between
Garve and the Carron that flows into the Dornoch firth.

In the flaky muscovite biotite schists, and in the quartzose granulites,
bands of garnet amphibolite and hornblende schists occur, which have
a wide distribution and are characteristic of certain horizons.

Reference must now be made to the foliated granite, intrusive in
the Moine series, which is one of the most interesting features in the
geology of the Conou basin. Its boundaries are of prime importance,
because the distribution of the boulders supplies valuable evidence
regarding the direction of the ice-flow during the glacial period. There
are two important masses of these older intrusive rocks. The larger
one extends from Cam nan Aigheinn, near the head of Strath Rannoch,
north-east by Carn Chuinneag to Cnoc an Liath-bhaid beyond Strath
Rusdale, and measures about 12 miles in length and about 5 miles in
breadth. The smaller one stretches from the hills above Loch Luichart
north-east by Inchbae to Carn More east of Strath Rannoch, being
about 5 miles long and less than 3 miles broad. Again, on the north
shore of Loch Luichart there are four outcrops of foliated granite,
evidently belonging to the same set of intrusions. The Inchbae type
of augen-gneiss or granite is well known, with large porphyritic crystals
of orthoclase felspar oriented in a definite direction, enclosed in a
granulitic ground-mass of quartz, felspar, and micas, together with
crystals of garnet and sphene. This coarse porphyritic variety is
largely developed in the Carn Chuinneag mass, where it is associated
with foliated riebeckite granite or augeii gneiss. Frequently the rock
is fine grained, and merges into a finely crystalline schist.

Evidence has been obtained that these older granite masses with
their basic modifications were intruded into the series of Moine
sediments before they were converted into crystalline schists. A well-
marked aureole of contact metamorphism accompanied this intrusion,
which in places has been obscured by subsequent deformation. But
at intervals round the margin the sediments are hornfelsed, and still
show their original bedding-planes, while garnets and crystals of
andalusite have been developed. It is further apparent that the granite
masses and the Moine sediments have been subjected to a common series
of dynamic stresses, for the planes of schistosity in the granite are

286 BATHYMETRICAL SURVEY OF

parallel to those in the Moine schists ; indeed, in certain localities they
pass, irrespective of the boundary-line, from the igneous to the altered
sedimentary rocks.

On either side of the Sutors of Cromarty, and stretching southwards
along the sea-cliff to Fortrose, there is a narrow belt of crystalline schists
rising from underneath the Old Red Sandstone. They belong to the
group of quartz biotite granulites, and are associated with bands of
amphibolite.

Newer granite masses are also represented in the area, as, for
instance, on the hills north of Ardross Castle above Strath Rusdale,
and in Glen Orrin west of Fairburn House. They resemble the normal
types of the newer granite masses of the Highlands, and were erupted
after the Moine schists had assumed their present crystalline character.

The strata of Old Red Sandstone age in the basin of the Cromarty
firth are arranged in the form of a great syncline, whose axis runs in a
north-north-east and south-south-west direction. The base of the series
and the order of succession are admirably displayed on the sea-cliffs at
Cromarty, and on the south-east shore of that firth as described long
ago by Hugh Miller. The basal conglomerate is there overlain by the
well-known fish-band, with calcareous nodules, graduating upwards
into the coarse sandstones that form the centre of the basin. On the
west side of the firth a similar sequence is observable. The basal con-
glomerate along the flanks of the hills is usually brought into conjunction
with the crystalline schists by a fault, evidently of no great amount, for
the unconformity is visible at certain localities. This horizon is sur-
mounted by red sandstones and flagstones, calcareous and bituminous
shales, and occasional intercalations of clays with limestone nodules,
with fish remains. These are followed by an upper band of conglomerate,
which is overlain by the coarse sandstones in the centre of the basin.

Various outliers of Old Red Sandstone, largely composed of con-
glomerate, and resting unconformably on the highly denuded platform
of crystalline schists, occur some miles to the west of the main area of
this formation in the Conon basin. Some of these are met with on the
plateau between Loch Luichart and Aultguish. By far the largest and
most important is that still further north in Strath Vaich, where an
extremely coarse conglomerate, composed largely of blocks of the
contiguous foliated granite, is found on the crest of Meall a' Ghrianain
(2531 feet).

At the base of the sea-cliff formed by the crystalline schists and Old
Red Sandstone of the Black Isle and the North Sutor, there are small
patches of Oolitic rocks which have only a limited development. They
occur on the beach below high-water mark at Eathie and at Port-an-
Righ and Cadh-an-Righ near Sandwick. By means of the great fault
that traverses the line of the Caledonian Canal, and is continued
north-east along the shore of the Black Isle, these Secondary strata
have been let down against the older rocks.

THE FRESH- WATER LOCHS OF SCOTLAND. 287

Regarding the lines of displacement in the Conon basin, one of the
most important is that just referred to, which skirts the base of the Black
Isle, and is prolonged north-east to Tarbat Ness, whereby this straight
feature has been determined. The great fault that traverses Loch
Maree and Glen Docharty passes south-east by Ledgown, thence across
the watershed by Carn Chaorainn to Loch Beannachan in the basin if
the Meig. Another powerful dislocation, nearly at right angles to the
course of the Loch Maree fault, has determined the north-north-east
direction of the Meig valley between Inbhir-Chaorainn and Milton
of Strathconon, and stretches south-west up Glen Chaorainn in the
direction of Loch Monar, and north-north-east to the head of Loch
Luichart.

During the period of extreme glaciation it would appear that the
ice-shed lay some distance to the east of the existing watershed in part
of the Conon basin, for boulders of foliated granite or augen gneiss,
from one or other of the masses near Inchbae, have been carried west-
ward into the valley of Loch Broom, to Inverlael, and nearly as far as
Ullapool. Their distribution in an eastward direction is no less
remarkable, for they have been traced as erratics across the Black
Isle and the Moray firth to the plain of Moray and the low grounds of
Banff shire. The boulder clay of the north part of the Black Isle
contains numerous blocks of this well-known rock, which were probably
dispersed during the greatest extension of the ice. Such evidence is in
harmony with that obtained in the Assynt district, where blocks of the
eastern schists have been carried from the plateau of the Moine schists,
east of the existing watershed, to higher elevations to the west, formed
of Cambrian strata. In view of these facts, it seems probable that
during one stage of the glacial period the Conon basin must have been
buried under an ice-sheet that overtopped the highest hills, the move-
ment of which was largely independent of the physical features of the
region.

During the period of confluent glaciers that ensued, the great
mountain groups formed more or less independent centres of dispersion.
Indeed, many of the striae, the disposition of the moraines, and the
distribution of the carried blocks furnish evidence relating to this
phase of glaciation. In the Fannich mountains — a range running east
and west for about 7 miles, and whose main peaks rise above 3000 feet —
ice-markings were found on the southern slopes at elevations between
2250 and 2500 feet trending south-south-east. Striae pointing in a
similar direction occur at various points on the ridge between Loch
Fannich and Strath Bran, thus showing that at one period the Fannich
ice must have crossed that loch into the Bran valley. Again, during
this later glaciation, ice crossed the watersheds from Glen Fhiodaig
and from Strath Conon into the valley of the Bran, and after uniting
with the glaciers from Fannich and the Blackwater, passed eastwards

288 BATHYMETRICAL SURVEY OF

by the Conon valley towards the Black Isle. The striae, trending about
east-south-east, found on the tops of Meall na Speirag and Beinn Liath
Beag at elevations of about 2000 feet, on the watershed between the
Blackwater and the streams flowing into Loch Luichart, clearly show
the development of the ice during this period.

Important evidence regarding the transport of materials during the
time of the confluent glaciers is furnished by the distribution of boulders
of foliated granite and Old Red Sandstone on the slopes of Ben Wyvis.
These have been carried from the west or west-north-west, and have
been traced up to a height of 2400 feet on Cam Gorm and Little Wyvis,
while their upper limit on Ben Wyvis itself is 2300 feet. It is further
apparent that the ice moved through the pass between Little Wyvis and
An Cabar, and streamed down the valley of Loch Glass north of Ben
Wyvis. Still further north in Kildermorie forest and Strath Rusdale,
the direction of the ice-flow was south of east, as proved by the striae,
and the transport of boulders of foliated granite or augen gneiss. From
the period of confluent glaciers to the time of their disappearance in
the upland glens, the various stages of retrocession are represented by
the moraines.

Loch Fannich. — The soundings clearly show that this lake gradually
deepens towards the eastern portion, the deepest sounding, 282 feet,
being situated about a mile above the outlet. The hill-slopes on both
sides of the loch for considerable distances are covered with morainic
drift, save near the outlet, where there is a prominent barrier of rock.
At the latter point the southern spur of An Coileachan approaches the
northern margin of the lake, and is prolonged on the south side in An
Cabhar and Carn na Beiste. Along the eastern side of this ridge, the
quartzose granulites and muscovite biotite schists are isoclinally folded
on vertical axes striking north and south — that is, at right angles to
the course of the lower part of the loch. At the outlet, and for a mile
below that point, the Grudie river flows on alluvial deposits, these
materials having been largely contributed by side streams, and especially
by Allt a' Choin Idir, draining from the north. Beyond the alluvium,
at the 800-feet level, the Moine schists are exposed in the bed of the
river and on the hill-slopes, and there is here no indication of a pre-
glacial river channel filled with drift. The surface of Loch Fannich is
822 feet above Ordnance datum, so that the depth of the rock basin
below the rocky barrier, visible about a mile beyond the outlet, is
260 feet.

Loch Luichart. — This lake is a true rock basin lying among the
crystalline schists, with a barrier formed of these materials at its outlet.
Where the stream issues from the loch, it runs through a narrow gorge
of rock and over successive waterfalls. In this sheet of water there are
three basins, of which the most westerly is the most important, its
greatest depth being 164 feet. The surface of the lake is 250 feet above

THE FRESH-WATER LOCHS OF SCOTLAND. 289

Ordnance datum line. The axis of the upper part of the loch coincides
with the strike of the crystalline schists, while that of the lower is
obliquely across it. It is interesting to note that the deepest basin has
been excavated out of the flaky muscovite biotite schists, while the
shallow part about the middle of the loch north of Creag Mhor cor-
responds with a belt of highly siliceous Moine schists folded over a core
of gneiss of Lewisian type. The head of the lake nearly coincides with
the Strath Conon fault already referred to, which crosses the lake in
a north-north-east direction, and has there produced considerable
brecciation of the strata. Only a small part has been silted up at the
western end by the alluvial material brought down by the Bran and
the Grudie.

Loch a' ('liroixy and Loch Crann. — The former lake is evidently a
rock basin, for, though at its outlet it flows over alluvial deposits that
mark the site of an old lake, the rocky barrier appears about 2 miles
east of Achnasheen, where the 400-feet contour-line crosses the Bran
river. The surface of the loch is 508 feet above Ordnance datum, and
the deepest sounding is 168 feet, so that the depth of the loch below the
rocky barrier beyond Achnasheen is 60 feet. Loch Crann has been
separated from Loch a' Chroisg by a cone of alluvium brought down by
the streams on both sides of the valley at that point.

Loch Aduinalt and Loch a' ChuiUtui represent the remains of a lake
which once extended for 4 miles up the valley to Dosmuckeran, the level
of which has been lowered by the Bran. The materials cut through
during this process of denudation consisted of moraine matter, but the
river has now reached the solid rock. The terraces round Loch Achanalt
and Loch a' Chuilinn rise to a height of 20 feet above the surface of
these sheets of water. The deepest sounding in the former is 9 feet, and
in the latter 43 feet. While Loch Achanalt is being rapidly silted up
by alluvial detritus, Loch a' Chuilinn preserves its character of a rock
basin. At its outlet the water flows over an ice-moulded surface of
granulitic quartzose schist. The strike of the strata is nearly parallel
with the long axis of the loch.

Loch Beannachan. — As already indicated, this lake lies along the
line of the powerful fault that has been traced in a south-east direction
from Loch Maree and Glen Docherty.

Loch Garve is evidently the remnant of a much larger sheet of water
that formerly extended from Little Garve down to the Falls of Rogie —
a distance of about 4 miles. The former level of the lake has been
lowered by the erosion of the drift deposits and the cutting of the rock
gorge at the Falls of Rogie. The surface of the present loch is 220 feet
above Ordnance datum line, and the deepest sounding is 105 feet. The
200-feet contour-line crosses the stream at these waterfalls. Hence,
on the assumption that the Moine schists and epidiorite sills exposed at

290 BATHYMETRICAL SURVEY OF

the latter locality formed the original rocky barrier of the lake, the
depth of water below this level in Loch Garve is still 84 feet.

Loch Achilty. — Though this lake is small, its extreme depth (119
feet) is remarkable. There is no proof that it occupies a rock basin, but
it is not improbable that such may partly be the case. Towards the
east it has been filled in by the delta gravels of the Blackwater, and
on the other side by those of the Conon at the time of the formation
of the 100-feet beach.

Loch Ussie is a shallow basin, 35 feet in depth, resting in drift ; and
Loch Kinellan appears to be banked by superficial deposits at the west
end, while at its eastern margin the bituminous shales of the Old Red
Sandstone are exposed. Its greatest depth is only 16 feet.

Loch Morie is obliquely traversed by a line of fault, with a down-
throw towards the south-west, that branches westwards in the upper
part of the basin. Each branch shifts the outcrop of the zone of
altered strata in contact with the mass of foliated granite already
referred to. The stream issuing from the' lake flows over a rocky barrier,
but it is possible that there may have been a former outlet now concealed
by drift.

Loch Glass. — Round the north-east margin there are traces of
terraces between Culzie Lodge and the foot of the lake. No rocky
barrier appears till the Falls of Eillenach are reached, where the stream
flows over a mass of conglomerate of Old -Red Sandstone age at an
elevation of about 680 feet. As the surface of the loch is 713 feet above
Ordnance datum line, and the deepest sounding is 365 feet, it follows
that the depth of water in Loch Glass below the level of the barrier at
the Falls of Eillenach is 332 feet.

Loch Eye lies on the stratified deposits of the 100-feet beach.

NOTES ON THE BIOLOGY OF THE LOCHS IN THE CONON BASIN.
By JAMES MUREAY.

The lochs of the Conon basin, with the exception of Loch Eye, which
will be separately noticed, have the plankton of a very uniform
character. The fauna includes only those species which are common
to the whole country, and calls for little detailed notice. The most
important feature in it is the .total absence of all those species of
Diaptomus (D. Wierzejskii, D. laticeps, D. laciniatus) which are
common in the districts to the north and south of the Conon valley.
This valley, extending nearly across Scotland, forms a line of inter-
ruption in the distribution of those species, a line completed towards
the west by Lochs Maree, Dhugaill, and Sgamhain, all of similar

THE FRESH- WATER LOCHS OF SCOTLAND. 291

character. Any slight peculiarity in the fauna will be noted under the
name of each loch.

In contradistinction to the absence of western species in the fauna of
these lochs, is the occurrence in the flora of several Desmids of the
western type. These western Desmids, though less numerous than in
districts both to the north and south, are in most of the lochs.

Loch Gown, North and South. — These very shallow basins had an
admixture of littoral species in the plankton, and the numerous
Desmids included both pelagic and bog species.

Loch a' Chroisg. — The only peculiarities of this loch were the
abundance of algae and of the smaller pelagic animals, such as Rotifera
and Protozoa. Floscularia pelagica, Rousselet, was abundant.

Loch Achanalt. — Owing to its shallow weedy character, littoral
species were more numerous than pelagic ones. A species of Gammarus
was of a bright slaty blue colour. Ophridium was abundant on the
weeds.

Loch a' Chuilinn. — Among the Rotifera observed were Euchlanis
lyra, E. dilatata, and Plcesoma truncatum. The Desmid Staurastrum
arctiscon was frequent.

Loch Fannich. — As in most of our largest lakes, there were skeletons
of ClathruUna elegans floating in the water. Although this is not a
true plankton organism (it lives attached by a stalk to plants), the
skeletons have seldom or never been observed during the Lake Survey
work except in large lakes, while it has rarely been seen living at the
margins of those lakes. The lightness of the skeletons, enabling them
to float on fresh water, may serve for the distribution of the species, and
small cysts are commonly seen in them. Granting this, their absence
from smaller lakes is- still unexplained. The only suggestion I can offer
is that the lower specific gravity, resulting from the higher temperature
of smaller lakes, may prevent the floating of the skeletons, or that the
higher temperature may lead to a more rapid decomposition of the
material of which they are composed, and so prevent their accumulation
in the water.

Loch Garve. — There was nothing peculiar in the plankton, except
the apparent absence of Desmids.

Loch Luichart. — In contrast with the neighbouring Loch Garve,
Desmids were here abundant, and other algae were also numerous.

Loch Achilty. — Desmids were numerous, including, among species
of the western type, Staurastrum arctiscon and S. jaculiferum.

Loch Kinellan. — Ceratium Jiirundinella was very abundant, of a
form with long divergent middle horns. There were also observed
Volvox globator, Asterionella with very short rays, a species of Cerio-
daphnia, and a few larvae of Corethra.

Loch Uxsie. — Ceratium hirundinella, of the same form as in Loch
Kinellan, was the most abundant organism. This was the only loch in
the district in which Latona setifera was seen.

292 BATHYMETRICAL SURVEY OF

Lochs Glass and Morie have no peculiarity worthy of remark,
except the much greater abundance of algae in Loch Glass.

Loch Eye. — This loch, which is only considered along with the Conon
lochs as a matter of convenience, really approximates biologically to
the lochs of the Shin basin, and of Sutherland generally. It is remark-
able for the abundance of Diaptomus Wierzejskii, this being the most
southern locality on the mainland where the type of the species has been
observed by the Lake Survey, though it extends much further south
in the Outer Hebrides, where Dr. Scott got it in Barra. The Rotifer
Triarthra longiseta was also abundant.

THE FRESH- WATER LOCHS OF SCOTLAND. 293

LOCHS OF THE SHIN BASIN.

THE lochs visited by the Lake Survey draining by the river Shin and
river Oykell into the Dornoch firth are Lochs Shin, Merkland, a'
Ghriama, Fiodhaig, Gorm Loch Mor, Ailsh, Craggie, an Daimh,
Migdale, and an Lagain, and it has been found convenient to include
also Loch Buidhe, flowing by the river Fleet into Loch Fleet, lying to
the north of the Dornoch firth. The drainage area, to be dealt with is
indicated on the index map (Fig. 48), and extends from Tarbat Ness
on the east to Cnoc a' Choilich (little more than 3 miles from the shores
of Loch Broom) on the west, and to Ben Hee and Carn Dearg on the
north, the total area being about 860 square miles, of which about 770
square miles drain into the Dornoch firth and about 90 square miles
into Loch Fleet. Of this total about 240 square miles drain into
the lochs under consideration, as will be seen from the summary
table on page 305. The principal loch is Loch Shin, one of the
largest of Scottish lochs, the others being comparatively small, Loch
Merkland being the only one exceeding 2 miles in length. Loch
Shin receives the outflow from Lochs Merkland and a' Ghriama at
its northern end, and the outflow from Loch Fiodhaig about 5 miles
down on its eastern shore. Gorm Loch Mor lies at the headwaters of
the river Cassley, a tributary of the river Oykell, and Loch an Daimh
flows by the river Einig into the river Oykell, which also receives the
outflow from Lochs Ailsh and Craggie. The river Shin, bearing the
outflow from Loch Shin, joins the river Oykell to form the Kyle of
Sutherland at the head of the Dornoch firth. Loch Migdale flows by
a short stream into the Dornoch firth on its northern side, and Loch an
Lagain flows by a longer stream (the river Evelix) also into the Dornoch
firth on its northern side. Loch Buidhe flows by the river Torboll into
the river Fleet at the head of Loch Fleet. The boundary-line between
Ross-shire and Sutherlandshire follows the course of the river Oykell
from the head of the Dornoch firth to Breabag Tarsuinn, passing up the
middle of Loch Ailsh, which thus lies partly in Ross and partly in
Sutherland, while Lochs Craggie and an Daimh are located in Ross-
shire and the remaining lochs under consideration in Sutherlandshire.

Loch Shin (See Plates LXV. and LXVI.).— Loch Shin is the largest
loch in Scotland to the north of Loch Ness, and, as regards length, it

294 BATHYMETRICAL SURVEY OF

ranks fifth of all Scottish lochs, being exceeded in this respect only
by Lochs Awe, Ness, Lomond, and Shiel. It is a fine sheet of water
situated amid beautiful scenery, with Ben More Assynt and Coniveall
rising to heights exceeding 3200 feet on the west, and Meall an Eoin
(3154 feet) on the north-east. It is a good trout loch, containing also
Salmo ferox, and the islands are much frequented by wildfowl. It
trends in a north-west and south-east direction, and the length measured
along the centre of the loch is about 17^ miles. The loch is on the
whole very narrow, the maximum breadth exceeding 1 mile at the
junction with the small arm leading to Loch a' Bhainbh, and also at
the position of the delta formation at the mouth of the river Fiodhaig.
Elsewhere the breadth is considerably less than a mile, and the upper
portion, to the north-west of the entrance of the river Fiodhaig, is all
less than half a mile in width. The mean breadth of the entire loch is
half a mile, or only 3 per cent, of the length — a percentage smaller than
has been observed in any other large loch except Loch Shiel. * The
waters of Loch Shin cover an area of about 5570 acres, or nearly 8|
square miles, and the area of land draining into it is over 150 square
miles, but as it receives the outflow from Lochs Merkland, a' Ghriama,
and Fiodhaig, its total drainage area is over 190 square miles — an area
22 times greater than that of the loch. Over 800 soundings were taken,
the maximum depth recorded being 162 feet, about 7 miles from the
foot of the loch, opposite the little Loch an Fhreiceadain on the north-
eastern shore. The volume of water contained in the loch is estimated at
12,380 millions of cubic feet, and the mean depth at 51 feet, or 31J per
cent, of the maximum depth. Loch Shin was surveyed on August 25 to
September 1, 1902, when the elevation of the lake-surface above the sea
was determined, by levelling from bench-mark, as being 270'85 feet;
when levelled by the officers of the Ordnance Survey on August 4, 1870,
the elevation was found to be 269-7 feet above sea-level. The farmer at
Overscaig stated that the water might fall 1 foot below, and rise 6 feet
above, the level at the time of the survey.

The floor of Loch Shin is very irregular. None of the contour-lines
are continuous from end to end of the loch, and the lines themselves
are usually of a sinuous character. The 25-feet contour encloses two
areas, the 50-feet contour three areas, the 100-feet contour four areas,
and the 1 50-feet contour two areas. The lower 25-feet basin is nearly
10 miles in length, extending from close to the lower end of the loch
as far as the alluvial cone at the mouth of the river Fiodhaig. Here
for an interval of nearly half a mile the soundings indicate depths less
than 20 feet, except for an isolated sounding of 25 feet towards the
north-eastern shore. The upper 25-feet basin is nearly 6 miles in
length, approaching to within half a mile from the head of the loch.

* See p. 242.

THE FRESH-WATER LOCHS OF SCOTLAND.

295

The lower 50-feet basin is about 8 miles in length, extending from
within a quarter of a mile from the southern end as far as the entrance
of the Allt a' Chairr Bhig. Separated from this lower basin by an
interval of more than half a mile there is a second small 50-feet basin
based upon soundings of 60, 70, and 80 feet. Proceeding up the loch
from this small basin there is an interval of nearly 3 miles before

01 2345

' English Miles

FIG. 48. INDEX MAP OF THE SHIN BASIN.

meeting with the upper 50-feet basin, which is 3J miles in length, and
approaches to within three-quarters of a mile from the head of the loch.
The lower 100 -feet basin lies about 2 miles from the foot of the
loch, and is about 2 miles in length ; the maximum depth recorded in
this basin was 140 feet, observed in two different places. Separated
from this lower basin by an interval of 1^ miles lies the central 100-feet
basin, enclosing the deepest part of the loch, which is about 2 miles
in length. The remaining two small 100-feet basins are situated
towards the head of the loch, the larger, distant about l\ miles from
the head, being 1 mile in length, and having a maximum depth of
129 feet, separated by an interval of half a mile from the smaller, based

296 BATHYMETRICAL SURVEY OF

upon soundings of 104, 106, and 108 feet. Within the central 100-feet
basin above mentioned the bottom sinks in two places below the depth
of 150 feet — (1) at the south-eastern end of the 100-feet basin, where
soundings of 156 and 157 feet were recorded; and (2) about half a
mile farther up the loch and towards the north-eastern shore, where
the deepest sounding in the loch (162 feet) was taken — apparently a
deep hole surrounded by much shallower water. A section across the
loch at the position of the deepest sounding is shown in cross-section
E-F on Plate LXVL, and similar sections are shown in cross-section
C-D on Plate LXV. taken towards the head of the loch, and in cross-
section G-H on Plate LXVI. taken towards the foot of the loch. In
these three sections the deepest part of the loch is seen to lie nearer to
the north-eastern than to the south-western shore, but this disposition
does not hold good throughout the loch, for in some of the other lines
of soundings the deepest casts were taken towards the south-western
shore. The longitudinal section A-B, placed at the foot of the two
maps, taken along the axis of maximum depth from end to end of the
loch, shows how irregular the lake-floor is along this central line, and
many of the lines of soundings indicate undulations more or less
pronounced, some of which give rise to striking sinuosities in the
contour-lines, while others do not affect the contours, or only slightly,
and are therefore not so easily remarked. As a rule, shallow water
is found offshore, but occasionally deep soundings were taken close
inshore — for instance, off the small promontory on the north-eastern
shore, 1J miles from the head of the loch, a sounding of 36 feet was
recorded ; farther down the same shore, off the mouth of the an Garbh-
allt, a sounding of 57 feet was taken ; near the pier at Shiness quarry
on the same shore depths of 32 and 40 feet were found ; and along the
opposite shore towards the foot of the loch depths of 32, 36, 37, and
38 feet were found here and there inshore.

The alluvial cone at the mouth of the river Fiodhaig has already
been referred to, and here shallow water extends right across the loch,
cutting it into two deeper portions. The land has been cut into 'a
delta-shaped form at the head of the loch, where the river from Loch
a' Ghriama flows into Loch Shin.

The areas between the consecutive contour-lines at equal intervals,
and the percentages to the total area of the loch, are as follows : —

0 to 50 feet 3260 acres 58 '5 per cent.

50,, 100 ,, 1480 ,, 26-6

100,, 150 „ 814 ,, 146
Over 150 , 14 0'3

5568 . 1000

These figures show that Loch Shin is comparatively shallow, 58 per

THE FRESH -WATER LOCHS OF SCOTLAND.

297

cent, of the lake-floor being covered by less than 50 feet of water, and
85 per cent, by less than 100 feet of water, while the area deeper than
150 feet is exceedingly small.

Temperature Observations. — Numerous surface temperatures were
taken during the week spent on the survey of Loch Shin, the readings
ranging from 56°-0 Fahr. to 590>0. Three serial temperatures were
taken, with the following results : —

Depth in feet.

August 27, 1902,
5.15 p.m.

August 30, 1902,
6 p.m.

September 1, 1902,
5.30 p.m.

0 Fahr.

0 Fahr.

0 Fahr.

0

56-5

56-7

57-0

2o

56-1

56-8

50

.-><;•<»

56-0

56-6

90

56-0

100

54-2

130

51*2

These observations show that the whole body of water down to a
depth of 90 feet was practically uniform in temperature, but in the
deepest part of the loch a fall of temperature amounting to 3° was
observed between 100 and 150 feet. The extreme range of temperature
from surface to bottom and from end to end of the loch amounted to
only 7°-8.

Loch Merkland (see Plate LXVII.). — Loch Merkland lies about 3
miles to the north of the head of Loch Shin, amid beautiful surroundings,
Ben Hee rising to a height of 2864 feet on the north-east, with Cam
Dearg (2613 feet) and other heights to the north, and Ben Leoid (2579
feet) to the west. It trends in a north-north- west and south-south-east
direction, and is 3 miles in length, with a maximum breadth of over
one-third of a mile, the mean breadth being a quarter of a mile. Its
waters cover an area of about 440 acres, or two-thirds of a square mile,
and it drains an area of about 16 square miles. Nearly 120 soundings
were taken, the maximum depth of 85 feet having been observed close
to the narrows towards the head of the loch. The volume of water is
estimated at 577 million cubic feet, and the mean depth at over 30 feet.
The loch was surveyed on September 2, 1902, when the elevation of the
lake-surface above the sea was found to be 360-2 feet.

Loch Merkland is comparatively simple in conformation ; the deeper
water occurs towards the head of the loch, and is cut into two portions
by a shoaling of the bottom at the narrow portion where the large
alluvial cone laid down at the mouth of the Allt nan Allbannach on the
north-eastern shore approaches the smaller cone at the mouth of the
Garbh Allt on the opposite shore. The depth of the channel at the
narrows referred to is 31 feet, and the 10-feet and 25-feet basins extend

298 BATHYMETRICAL SURVEY OF

from end to end, roughly approximating with the outline of the loch.
The principal 50-feet basin extends from the narrows for a distance of
three-quarters of a mile down the loch, and there is an isolated sounding
of 52 feet to the north-west of the narrows. The 75-feet basin is a long
and narrow area, half a mile in length, the deepest sounding having
been recorded at the upper end of this basin, and comparatively close to
the south-western shore, off which the slope is steep. This is well shown
in the cross-section E-F on the map, and at other places along both
shores the soundings indicate steep slopes. The longitudinal section
A-B shows the shoaling of the water at the narrows, deepening
immediately to the south-east to the maximum depth of the loch;
there is also a scarcely perceptible shoaling farther down the loch,
where a sounding of 37 feet was recorded, with 47 feet to the north-
west and 41 feet to the south-east. The areas between the consecutive
contour-lines, and the percentages to the total area of the loch, are
as follows : —

0 to 25 feet 190 acres 43 per cent.

25,, 50 „ 198 „ 45

50 „ 75 „ 37 „ 9

Over 75 „ 14 „ 3

439 „ 100 „

These figures show that the average slope is slightly steeper within
the 25-feet line than between 25 and 50 feet, and they also show how
circumscribed is the area deeper than 50 feet, 88 per cent, of the lake-
floor being covered with less than 50 feet of water.

Temperature Observations. — A series of temperatures taken in the
deepest part of the loch at 6 p.m. on the date of the survey gave the
following results : —

Surface 56°'8 Fahr.

25 feet 56°'2 „

50 , 56°-0 „

80 „ ' ... 55°'8 ,,

These observations indicate a range of only 1° from surface to
bottom.

Loch a' Ghriama (see Plate LXVIL). — Loch a' Ghriama (or Griam)
lies immediately to the north of the head of Loch Shin, into which its
waters are carried by a short rapid stream. The distance between the
two lochs is only a quarter of a mile, and at the time of the survey
there was a difference in level of nearly 33 feet. It is a good trout
loch, and Salmo feroz is also found in it. The principal feeder is the
Amhainn an Ceardaich, over a mile in length, bearing the outflow
from Loch Merkland. It trends almost north and south, and is 1J

THE FRESH- WATER LOCHS OF SCOTLAND. 299

miles in length, nearly uniform in width, the maximum breadth being
over a third of a mile, and the mean breadth over a quarter of a mile.
Its waters cover an area of about 260 acres, and it drains directly an
area of over 6^ square miles; but since it receives the outflow from
Loch Merkland, its total drainage area is over 22| square miles — an
area 57 times greater than that of the loch. The maximum depth
of 64 feet was observed approximately in the centre of the loch,
but rather nearer the northern than the southern end. The volume
of water is estimated at 314 million cubic feet, and the mean depth
at 28 feet. The loch was surveyed on September 1, 1902, when the
elevation of the lake-surface above the sea was found to be 303*7 feet,
which is almost identical with the elevation observed by the Ordnance
Survey officers on July 4, 1856, viz. 303-5 feet.

The conformation of Loch a' Ghriama is simple, with one or two
very slight undulations of the lake-floor, the principal of which gives
rise to a striking sinuosity in the 50-feet contour ; otherwise the contour-
lines coincide approximately with the outline of the loch. The 25-feet
basin is about 1J miles, and the 50-feet basin over half a mile, in length.
The longitudinal section C-D, and the cross section G-H taken at the
position of the deepest sounding, show generally a gradual slope down
to the greatest depth, and this is borne out by the following table,
giving the areas between the contour-lines and the percentages to the
total area of the loch : —

0 to 25 feet 121 acres 47 per cent.

25 „ 50 „ 106 „ 41 „

Over 50 „ 30 „ 12 „

257 .. 100

Temperature Observations. — The following series of temperatures,
taken at 3 p.m. on September 1, 1902, in the deepest part of Loch a'
Ghriama, indicates a range of only 2° from surface to bottom : —

Surface 57°'OFahr.

25 feet 56°'2 „

55 „ ... / 55°-0 „

Loch Fiodhaig (see Plate LXVIIL). — Loch Fiodhaig (or Fiodiag, or
Fiag) lies to the north-east of the head of Loch Shin, into which its
superfluent waters are carried by the river Fiodhaig (or Fiag). This is
a good trout loch, but the fishing is preserved, surrounded by moorland
hills, with Ben Hee rising to the north. It receives the outflow from
Loch a' Ghorm-Choire and another smaller loch lying to the north,
which were not sounded. The loch trends in a north and south
direction, and is over 1^ miles in length, with a maximum breadth
near the northern end of two-thirds of a mile. Its waters cover an

300 BATHYMETRICAL SURVEY OF

area of about 370 acres, or over half a square mile, and an area twenty
times greater — an area of over 11 \ square miles — drains into it. The
maximum depth of 71 feet was observed not far from the largest island
in the loch, and nearer the northern than the southern end. The
volume of water is estimated at 415 million cubic feet, and the mean
depth at nearly 26 feet. Loch Fiodhaig was surveyed on October 23,
1902, but the elevation above the sea was not determined by levelling;
judging from the contour-lines, the lake-surface is apparently nearly
700 feet above sea-level. The loch is irregular both in outline and
conformation. The lake-floor shows undulations, and in some places
deep water approaches very close to the shore, as may be seen in the
two sections on the map. The areas between the contour-lines, and
the percentages to the total area of the loch, are as follows : —

0 bo 25 feet 203 acres 55 per cent.

25,, 50 „ 133 „ 36

Over 50 , 33 , 9

369 ,, 100

The temperature of the surface water on the date of the survey was
48°-0 Fahr.

Gorm Loch Mor (see Plate LXIX.). — Gorm Loch Mor lies about
4 miles to the west of the head of Loch Shin, in a mountainous district,
with Beinn Leoid (2597 feet) to the north, Beinn Uidhe (2384 feet) to
the west, and Ben More Assynt (3273 feet) and Coniveall (3234 feet) to
the south. Its outflow is carried through a series of smaller lochs
(Fionn Loch Mor, Fionn Loch Beag, and Loch na Sroine Luime), which
could not be sounded, into the river Cassley. Though a comparatively
small loch, it has the distinction of being deeper than the other lochs
in the basin, except Loch Shin. It is very irregular in outline, and
includes many islands. The length of the loch, along a straight line
from north-west to south-east, is slightly over a mile ; but along a
line following the deeper water it is considerably more. The greatest
width in a north-and-south direction is over half a mile, the mean
breadth of the entire loch being less than a quarter of a mile. Its
waters cover an area of about 185 acres, or over a quarter of a square
mile, and it drains an area of 5J square miles. Nearly 70 soundings
were taken, the maximum depth of 91 feet being observed comparatively
close to the western shore. The volume of water is estimated at 196
million cubic feet, and the mean depth at over 24 feet. The loch was
surveyed on October 22, 1902, when the elevation of the lake-surface
was found to be 847*0 feet above the sea ; when visited by the Ordnance
Survey officers on October 1, 1870, the elevation was 846-4 feet above
sea-level.

THE FRESH- WATER LOCHS OF SCOTLAND. 301

The floor of Gorm Loch M6r is most irregular, islands and banks
and deep soundings being found here and there in close proximity,
while in other places deep water approaches close to the shore. The
contour-lines are of the most sinuous description, with isolated deep
and shallow patches. The deepest part of the loch runs along the
western shore, off which the slope is uniformly rather steep, and occurs
towards the north-western end, as will be seen in the longitudinal
section A-B on the map. The areas between the contour-lines, and
the percentages to the total area of the loch, are as follows : —

0 to 25 feet 126 acres 68 per cent.

25,, 50 „ 35 „ 19

50,, 75 „ 16 „ 8

Over 75 , 8 , 5

185 „ 100

Temperature Observations. — A surface reading at 10 a.m. on October
22, 1902, when commencing the survey, gave 44° Fahr., but at 2 p.m.
in the deepest part of the loch a series of temperatures gave identical
readings, viz. 46°'2, at the surface and at 10, 25, 50, and 75 feet.

LochAilsh (see Plate LXIX.). — Loch Ailsh lies about 10 miles to the
west of Loch Shin, with the heights of Ben More Assynt and Coniveall
rising to the north. It is a moderate-sized but rather shallow loch,
containing trout and an occasional salmon or grilse. It is irregular in
outline, slightly under a mile in length from north to south, with a
maximum width in the northern portion exceeding half a mile. Its
waters cover an area of about 245 acres, and it drains an area 44
times greater — an area of nearly 17 square miles. The maximum depth
of 24 feet was observed in the north-eastern part of the loch, less than
a quarter of a mile from the alluvial cone laid down at the mouth
of the river Oykell on the northern shore. The volume of water is
estimated at 88 million cubic feet, and the mean depth at 8J feet. The
loch was surveyed on September 6, 1902, when the elevation of the
lake-surface above the sea was found to be 498'5 feet, almost identical
with that observed by the Ordnance Survey officers on August 29, 1871,
viz. 498-4 feet. The highest drift-mark observed was 4 feet above the
level of the water on the date of the survey. The southern and western
portions of Loch Ailsh are covered by less than 10 feet of water, the
deeper part lying along the eastern shore and towards the north-eastern
angle of the loch. The area of the lake-floor covered by less than 10
feet of water is about 173 acres, or 71 per cent, of the entire area, while
that covered by more than 20 feet of water is only about 12 acres, or
5 per cent. The temperature of the surface water at 2 p.m. on the
date of the survey was 550>3 Fahr., and a reading at a depth of 20 feet
gave 54°.

302 BATHYMETRICAL SURVEY OF

Loch Cr aggie (see Plate LXIX.). — Loch Craggie is a small but rather
deep loch, less than 3 miles to the south of Loch Ailsh, the road from
Oykell Bridge to Lochinver running along the northern shore. It
trends in a north-west and south-east direction, is nearly two-thirds of
a mile in length, and covers an area of about 45 acres. The maximum
depth of 40 feet was observed approximately in the centre of the loch.
The volume of water is estimated at 30 million cubic feet, and the
mean depth at 15J feet. It was surveyed on September 23, 1902, when
the elevation of the lake-surface was found to be 505'95 feet above the
sea; when visited by the Ordnance Survey officers on August 26, 1871,
the elevation was 506'5 feet above sea-level.

Loch Craggie is quite simple in conformation. The water is deep
close to the shore all round, except towards the outflow at the south-east
end, the area of the lake-floor covered by less than 10 feet of water
being only about 15 acres, or 34 per cent, of the entire area ; more than
half of the bottom is covered by water between 10 and 25 feet in
depth, while about 6 acres, or 13 per cent., are covered by more than
25 feet of water. Temperature observations taken at 3.30 p.m. on the
date of the survey showed that the water was practically uniform in
temperature from surface to bottom, the reading at the surface being
52°-8 Fahr., and at the depths of 15 and 30 feet, 52°-5.

Loch an Daimh (see Plate LXIX.). — Loch an Daimh (or Damph) is
situated about 7 miles to the south-west of Oykell Bridge, and about
8 miles to the east of Ullapool on Loch Broom. Though at present in
the eastern watershed, the day may not be far distant when it will be
diverted to the west, for the small stream flowing into the Rhidorroch
river is cutting back rapidly, is much lower than the loch, and will
probably tap the loch at its south-west end. The shores rise well above
the loch, and the south-eastern shore is wooded ; it is a good trout loch,
but the fishing is preserved. Loch an Daimh is a narrow loch trending
south-west and north-east, nearly 1| miles in length, with a maximum
breadth of only one-fifth of a mile. Its waters cover an area of about
173 acres, or a quarter of a square mile, and it drains an area of about
2J square miles. The maximum depth of 52 feet was observed approxi-
mately near the centre of the loch, but towards the south-west end.
The volume of water is estimated at 205 million cubic feet, and the
mean depth at over 27 feet. The loch was surveyed on August 23 and
25, 1902, when the elevation of the lake-surface was found to be
671 '5 feet above the sea — identical with the elevation observed by the
Ordnance Survey officers on August 1, 1870; during the winter of
1901-2 the water rose 2 to 3 feet.

Loch an Daimh is extremely simple in conformation, with no pro-
nounced irregularities of the lake-floor. The 10-feet and 25-feet basins
extend from end to end, and the 50-feet basin, half a mile in length,

THE FRESH- WATER LOCHS OF SCOTLAND. 303

occupies a central position. The offshore slope is in some places very
steep, and the average slope outside the 25-feet contour is steeper
than in the deeper water between 25 and 50 feet, as shown in the
following table giving the areas between the contour-lines, and the
percentages to the total area of the loch : —

0 to 25 feet 77 acres 44 '5 per cent.

25 „ 50 „ 87 „ 50-6 „

Over 50 , 9 . 4 -9

173 „ 100-0

The surface temperature on August 23, 1902, at 12.30 p.m., was
57° Fahr.; and on August 25, at 11.45 a.m., 56°.

Loch Migdale (see Plate LXX.). — Loch Migdale is situated close to
the northern shore of the Dornoch firth, and less than a mile from Bonar
Bridge at the head of that firth. It contains trout and pike, and the
surrounding scenery is very fine, a conspicuous hill called Migdale Rock
rising off the north-eastern shore. The island at the west end of the
loch is artificial, composed of large and small stones ; a crossing passes
from the western shore to the island, and was covered by a foot of water
at the time of the survey. The loch trends in a north-west and south-
east direction, and is nearly 2 miles in length, with a maximum width
of nearly half a mile towards the north-west end, the loch narrowing
gradually towards the opposite end. Its waters cover an area of
about 260 acres, and it drains an area of about 7J square miles. The
maximum depth of 49 feet was observed rather nearer the north-west
than the south-east end. The volume of water is estimated at 242
million cubic feet, and the mean depth at over 21 feet. Loch Migdale
was surveyed on September 24, 1902, when the elevation of the lake-
surface was found to be 113-6 feet above the sea; when visited by the
Ordnance Survey officers on November 1, 1869, the elevation was 115'1
feet above sea-level.

The loch forms a simple basin, with a few minor undulations of
the lake-floor. The contour-lines approach nearer to the eastern end,
where the Spinningdale burn flows out, the water being shallower
towards the opposite end, with weeds growing off the northern shore,
at the entrances of Migdale burn and Munroe's burn. The area of the
lake-floor covered by less than 10 feet of water is about 70 acres, or
27 per cent, of the total area, while that covered by more than 25 feet
of water is about 94 acres, or 36 per cent. Temperatures taken at
6 p.m. on the date of the survey, in the deepest part of the loch,
showed very little variation in the temperature of the water, the reading
at the surface being 54°-9 Fahr., at 25 feet 54°'l, and at 40 feet 54°.

304 BATHYMETRICAL SURVEY OF

Loch an Lagain (see Plate LXX.). — Loch an Lagain (or Laggan)
lies about 3J miles to the north-east of Bonar Bridge. It receives the
outflow from Loch Laro (which was not sounded), and its superfluent
waters are carried by the river Evelix, after a long winding course,
into the Dornoch firth. It is a small, comparatively shallow loch,
trending almost east and west, one mile in length, with a maximum
width towards the western end of nearly a quarter of a mile, narrowing
gradually towards the eastern end. Its waters cover an area of about
68 acres, and it drains a relatively large tract of country, the area of
which exceeds 8 square miles — an area 74 times greater than that of
the loch. The maximum depth of 18 feet was observed near the centre
of the loch, but towards the northern shore. The volume of water
is estimated at 23 million cubic feet, and the mean depth at 1\ feet.
The loch was surveyed on September 25, 1902, but the elevation
of the lake-surface above the sea could not be determined; the
Ordnance Survey officers levelled the loch on November 23, 1869, and
found the elevation to be 446'2 feet above sea-level. The lake-floor
is quite simple in conformation, with no irregularities, the deeper water
approaching nearer to the eastern than to the western end; the area
covered by less than 10 feet of water is about 49 acres, or 71 per cent,
of the total area of the loch. The temperature of the surface water was
53°-0 Fahr., and a reading at a depth of 9 feet gave 52°-9.

Loch Buidht (see Plate LXX.). — Loch Buidhe (or Buie) lies amid
moorland hills about 5 miles to the north-east of Bonar Bridge, the road
from that place to Golspie running along its southern shore. It receives
the outflow from Lochs Cracail Mor and Cracail Beag (which were not
sounded), and flows, as already stated, into the head of Loch Fleet. It
is a good trout loch, but an attempt to introduce salmon failed. The
loch trends east and west, and is 1J miles in length, with a maximum
breadth of nearly a quarter of a mile. Its waters cover an area of about
133 acres, and it drains an area of about 8| square miles — an area over
40 times greater than that of the loch. The maximum depth of 36 feet
was observed approximately in the centre of the loch. The volume
of water is estimated at 68 million cubic feet, and the mean depth at
11| feet. The loch was surveyed on September 25, 1902, when the
elevation of the lake-surface above the sea was found to be 528-45 feet ;
when visited by the officers of the Ordnance Survey on May 21, 1870,
the elevation was 527-3 feet above sea-level. By means of the sluice
at the east end of the loch the level of the water may be raised 4 or
5 feet, but it is seldom, or never, used; according to the keeper, the
water may fall 2 feet below the level on the date of the survey.

Loch Buidhe is quite simple in conformation, the bottom sinking
gradually on all sides from the shore to the deepest part, which occupies
a central position. The area of the lake-floor covered by less than 10

THE FRESH- WATER LOCHS OF SCOTLAND.

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306 BATHYMETRICAL SURVEY OF

feet of water is about 66 acres, or 50 per cent, of the total area of the
loch, while that covered by more than 25 feet of water is about 4 acres,
or 3 per cent. Temperature observations taken in the deepest part of
the loch at 1.30 p.m. on the date of the survey showed little variation,
the reading at the surface being 52°- 6 Fahr., at 20 feet 52°-l, and at
30 feet 52°-0.

The particulars regarding the lochs of the Shin basin are collected
together in the table on p. 305 for convenience of reference and
comparison. From this table it will be seen that in the eleven lochs
under consideration, which cover an area of over 12 square miles,
nearly 1600 soundings were taken, or an average of 129 soundings per
square mile of surface. The aggregate volume of water contained in
the lochs is estimated at 14,500 millions of cubic feet, and the area
draining into them is nearly 240 square miles, or twenty times the
area of the lochs.

NOTES ON THE GEOLOGY or THE SHIN BASIN.
By B. N. PEACH, LL.D., F.R.S., and J. HORNE, LL.D., F.R.S.

Of the area included in the basin of the Shin, only narrow belts
along the west, north, and east margins have been mapped by the
Geological Survey. The greater part of the tract is occupied by
crystalline schists of the types so largely developed in the counties of
Sutherland and Ross, to the east of the line of complication which
stretches southwards from Loch Eriboll by the headwaters of the
Cassley and the Oykell rivers to Ullapool. The course of the Moine
thrust — the most easterly of the great Post-Cambrian displacements
described in the " Notes on the Geology of the Assynt District "* —
runs south from Gorm Loch Mor by Loch Ailsh to near Loch Craggie,
thence it curves westwards to Knockan beyond the limits of the Shin
basin. East of this dislocation, the metamorphic rocks include quartz
schists, quartz-biotite granulites, garnetiferous muscovite-biotite schists
and flaggy micaceous gneisses. These are pierced by igneous materials
(granite and diorite) that cover considerable areas, as near Lairg.

Along the eastern part of the basin there is a belt of Old Red
Sandstone strata running in a north-east and south-west direction, its
western limit being approximately denned by a line drawn from the
Mound station to a point west of Edderton station. Both the middle

See p. 178.

THE FRESH- WATER LOCHS OF SCOTLAND. 307

or Orcadian and the upper divisions of this formation are represented,
the latter occurring between Tain and Tarbat Ness and northwards
along the shore by Dornoch.

Gorm Loch Mor. — This lake, situated in the high plateau east of
Ben More, lies in a rock basin formed mainly of Cambrian quartzite.
Part of the floor, where the Garbh Allt enters the loch, may be composed
of thrust Lewisian gneiss underlying these quartzites. The deepest
sounding is 91 feet, and at the outlet the water flows over ledges of the
higher or " pipe-rock " zone of the quartzite. Around the lake, the
traces of glaciation are extremely abundant. Both the striae and the
disposition of the carried boulders prove that, during the greatest
extension of the later glaciers, the ice radiating from the east side of
the Ben More range crossed the ridge in a north-east direction beyond
Gorm Loch Mor and overflowed into Loch Shin. At a later stage, the
glacier that issued from Coire a' Mhadaidh curved round Cailleach an
t-Sniomha on the west side of Gorm Loch Mor, and moved north-west
by Glen Beg to the head of Loch Glencoul. The quartzite plateau in
the east part of the lake is dotted over with moraines, which there form
the islands.

Loch Aihh is a shallow lake — the greatest depth being 24 feet —
partly enveloped in drift and solid rock. It rests on various zones of
Cambrian age, including the quartzite, Fucoid beds, serpulite grit,
and limestone with intrusive igneous materials, all overlying the Ben
More thrust-plane. From the covering of drift, it is uncertain whether
this lake is a true rock basin. Its surface level is 498'5 feet, and the
rock first appears at the outlet at a height of 490 feet above Ordnance
datum line.

Loch Cr aggie is a true rock basin, the deepest sounding being 40 feet.
The rocky barrier is formed by siliceous schists and mica-schists that
are well exposed in the stream below the outlet and by the side of the
road along the north bank of the lake. The height of the surface of
the water above sea-level is 505-95 feet, and that of the solid rock where
the bridge spans the Craggie burn below the outlet is 505 feet. The
direction of the ice-movement during the later glaciation was parallel
with the long axis of the lake.

Lnch an, Daimh lies along a line of dislocation or fault that has been
traced for a long distance in the crystalline schists south-westwards
towards the head of Loch Broom. In the streams draining the hill
slope on the northmost side the strata are exposed, which there consist
of quartzose granulites with intercalations of mica-schist. On the
higher part of the declivity the beds dip at gentle angles to the south-
east, but on approaching the lake they are thrown into rapid folds
parallel with its long axis, and are much crushed and shattered. At
its lower end the lake is invaded by cones of alluvium brought down by
the streams on either side.

308 BATHYMETRICAL SURVEY OF

NOTES ON THE BIOLOGY OF THE LOCHS OF THE SHIN BASIN.
By JAMES MURRAY.

Collections of plankton were made in eight lochs of the basin. The
lochs are mainly characterised by the presence of two northern species
of Diaptomus (D. laciniatus and D. laticeps), besides the common
D. gracilis, and by the very numerous Desmids, many of which are of
the western type.

Each of the three species of Diaptomus was found in five lochs —
D. gracilis in Lochs Shin, a' Ghriama, Ailsh, Gorm Loch Mor, and
Fiodhaig ; D. laciniatus in Lochs Shin, a' Ghriama, Merkland, Ailsh, and
an Daimh ; D. laticeps (or a related species) in Lochs a' Ghriama, Ailsh,
an Daimh, Gorm Loch Mor, and Fiodhaig. All three species occurred
together only in two lochs (a* Ghriama and Ailsh), while in all the
other lochs, except Merkland and an Lagain, there were two species;
in Loch Merkland D. laciniatus was the only species seen. D. laticeps
was identified in Lochs a' Ghriama and Ailsh; in Lochs an Daimh,
Gorm Loch Mor, and Fiodhaig, a species of the same group occurred,
but as only females or immature males were seen, it is not certain
whether they were D. laticeps or the very closely related D. Wierzejskii.

Among other Crustacea there is little to note — Holopedium was
only seen in Lochs Shin and a' Ghriama; Leptodora in Lochs Shin,
a' Ghriama, and an Daimh ; Sida in Loch a' Ghriama only ; DiapJiano-
soma in nearly all of the lochs. Nearly all the Daphnice of Loch
Fiodhaig were males.

Ilyocryptus acutifrons, G. O. Sars, was found in Loch Shin in
August, 1903, being previously unrecorded for Great Britain. It was
obtained in a shallow bay at the mouth of the Fiodhaig river.

The Desmids of Loch Shin have been fully studied by Messrs. W.
and G. S. West.* On the occasion of our visit the very great abundance,
of individuals as well as species, was remarkable, exceeding anything
that we had observed in other lochs. In Lochs a' Ghriama and Merk-
land the species were also very numerous, and on the whole the same as
in Loch Shin. In Lochs Ailsh, an Daimh, and an Lagain, few Desmids
were seen, but all had some of the western species. In Gorm Loch
Mor and Loch Fiodhaig no Desmids were noted.

Pelagic Rotifera were abundant only in Lochs Shin, a' Ghriama, and
Ailsh; in Loch Shin the plankton collections also included many
littoral species, which must have been driven out by the stormy
weather. Floscularia pelagica, Rousselet, was in Loch a' Ghriama
only. Skeletons of the Heliozoan, Clatlwulina elegans, were abundant
in Lochs Shin and a' Ghriama.

* See Journ, Linn. Soc., Bot., vol. 35, p. 519, 1903.

THE FRESH-WATER LOCHS OF SCOTLAND. 309

LOCHS OF THE NAVER BASIN.

THERE are five lochs within this basin to be dealt with here, of which
the largest is Loch Naver, though Loch Coir' an Fhearna has a greater
depth ; a few small lochs within the basin could not be sounded by the
Lake Survey for lack of boats. The overflow from Loch na Meide is
carried by the Amhainn Bheag and River of Mudale into Loch Naver,
and shortly after leaving Loch Naver the river Naver is joined by the
river Mallart, bearing the overflow from Lochs a' Bhealaich and Coir'
an Fhearna, while still further on the river Naver is joined by the
Langdale burn, bearing the overflow from Loch Syre. Of the total
area of the basin (nearly 200 square miles), about 119 square miles,
or 60 per cent., drain into these five lochs.

Loch na Meide (see Plate LXXI.). — Loch na Meide (or Meadie) lies
about 10 miles to the south of Tongue, and about 22 miles to the north
of Lairg, which is the nearest railway station. It trends nearly north
and south, and is very irregular in outline, the northern portion being
narrow, while the southern portion widens out considerably ; there is a
very narrow and shallow constriction near the middle, which practically
cuts the loch into two portions. It is 3J miles in length, and has a
maximum breadth near the southern end of over a mile, the mean
breadth of the entire loch being a quarter of a mile. Its waters cover
an area of about 555 acres, or nearly 1 square mile, and it drains an
area of 8 square miles. The maximum depth of 63 feet was observed in
the wide southern portion of the loch, but towards the eastern shore,
about 650 yards from the southern end, and only about 100 yards from
one of the small unnamed islands. The volume of water is estimated at
498 million cubic feet, and the mean depth at 20J feet. The loch was
surveyed on September 25, 1902, when the elevation of the lake-surface
was found, by levelling from bench-mark, to be 488*35 feet above the
sea.

Loch na Meide is very irregular in conformation, with many small
islands in the southern half, the largest of which is named Eilean Mor.
The deepest water was found near the southern end; a sounding in
44 feet was taken about 200 yards from the southern shore, and there is
a small area about one-third of a mile in length exceeding 50 feet in

310

BATHYMETRICAL SURVEY OF

depth. In close proximity a sounding of 22 feet was taken, surrounded
on all sides by deeper water. On approaching the central constriction,
in which the depth is only 2 feet, the water shoals gradually though
irregularly, and deepens again on proceeding towards the northern end,

English Miles
e 3 •*«. s

FIG. 49. — INDEX MAP OF THE NAVER, BOUGIE, KINLOCH, AND HOPE BASINS.

where a maximum depth of 40 feet was observed about half a mile
from the upper end, and where there is a small area about one-third of
a mile in length exceeding 30 feet in depth. The following table
gives the areas between the contour-lines, and the percentages to the
total area of the loch, and shows that on the whole Loch na Meide is

THE FRESH- WATER LOCHS OF SCOTLAND. 311

rather shallow, since 70 per cent, of the lake-floor is covered by less
than 25 feet of water: —

0 to 25 feet 388 acres 70 per cent.

25,, 50 „ 149 „ 27

Over 50 , 18 , 3

555 „ 100 „

The temperature of the surface water at 10 a.m. on the date of the
survey was 530-0 Fahr. The deposits brought up were all very dark
(black) muds.

Loch Naver (see Plate LXX1I.). — Loch Naver lies about 5 miles to
the south-east of Loch na Meide, with Ben Klibreck to the south rising
gently up from the shore of the loch. Altnaharra Inn, at the west end
of the loch, is a well-known rendezvous for anglers. On the northern
shore Reidhachaisteil and Gruamamor,- and on the southern shore
Ruighnasealbhaig, are the remains of considerable villages destroyed
at the beginning of last century when the crofters were turned out.
There are the ruins of Pictish towers near Gruamamor and on the
island close to the opposite (southern) shore, and the remains of several
artificial crannogs rise towards the surface of the water, in one case
reaching above the surface. Loch Naver is broadly sinuous in outline,
the general trend being east-north-east and west-south-west, while the
upper portion for about a mile runs east and west, and it exceeds 6
miles in length. It is a comparatively narrow loch, the maximum
width towards the west end not exceeding two-thirds of a mile, whence
the width gradually diminishes towards the east end, the mean breadth
of the entire loch being about one-third of a mile, or 6 per cent, of the
length. Its waters cover an area of about 1446 acres, or 2J- square
miles, and it drains directly an area of nearly 81 square miles; but
since it receives the outflow from Loch na Meide, its total drainage
area is nearly 89 square miles. The maximum depth of 108 feet was
observed in the wider part of the loch about a mile from the west end.
The volume of water contained in the loch is estimated at 2461 millions
of cubic feet, and the mean depth at 39 feet. The loch was surveyed
on September 24 and 25, 1902, when the elevation of the lake-surface
was determined, by levelling from bench-marks, as being 247 '6 feet
above the sea ; when visited by the officers of the Ordnance Survey on
June 24, 1870, the elevation was found to be 246'9 feet above sea-level.
The highest drift-mark observed was 4J feet above the surface of the
water at the time of the survey, and it was said that the water might
fall to the extent of 4 feet, giving a range in level of about 8J feet.

The floor of Loch Naver is rather irregular, as may be seen in the
longitudinal section taken along the axis of maximum depth, which

312 BATHYMETRICAL SURVEY OF

shows how the bottom rises and falls on proceeding from one end of
the loch to the other. The 25-feet contour-line is discontinuous opposite
the entrance of the Allt Gruama Beag, where the deepest sounding was
24 feet, the water deepening both to the east and to the west. The
50-feet contour is continuous, enclosing an area nearly 4 miles in length,
distant from the east end about 1| miles, and approaching to within
one-third of a mile from the west end ; within this area, however, the
bottom rises in two places, where soundings of 40 and 43 feet were
taken. There is a small isolated 75-feet area opposite Carn Gruama
Beag, based on soundings of 76 and 80 feet, separated from the principal
75-feet basin by an interval of over a quarter of a mile, in which the
greatest depth is 62 feet; the main 75-feet area is 2J miles in length,
and approaches to within three-quarters of a mile from the west end.
There are two very small 100-feet areas, based upon isolated soundings
of 100 and 108 feet, the former opposite Gruamamor, the latter farther
up the loch west of Reidhachaisteil. A short distance to the west of
the deepest sounding (108 feet) is a rise of the bottom covered by 40
feet of water already mentioned, and to the north-east near the northern
shore is a bank covered by only 1 foot of water surrounded by much
deeper water. Off the southern shore at Coill Ach' a' Chuil, towards
the east end of the loch, is another bank with 6 feet of water on it,
in close proximity to a sounding of 30 feet. The following table gives
the areas between the consecutive contour-lines and the percentages
to the total area of the loch : —

0 to 25 feet 551 acres 38 '1 per cent.

25,, 50 „ 425 „ 29-4 „

50,, 75 „ 301 „ 20-8

75,, 100 ,, 167 „ 11-6

Over 100 , 2 . O'l

1446 . 100-0

Temperature observations taken on September 24, 1902, gave
readings of 54° Fahr. at the surface, at 25 feet, and at 50 feet; while
at 80 feet the temperature was 53°'5.

Loch a' Bhealaich (see Plate LXXIII.).— Loch a' Bhealaich (or
a-Vellich, or Vealloch) lies about 4J miles to the south of the western
portion of Loch Naver, with Ben Klibreck rising between them. It is
almost continuous with the larger Loch Coir' an Fhearna, the connect-
ing stream between them being only about 200 yards in length, and the
difference in level less than 2 feet. To the north of the two lochs
Ben Klibreck slopes gently up to over 3000 feet, while the ground to
the south is not so high, but much steeper ; so steep is that around
Loch a' Bhealaich (which lies in a very fine corrie) that even at noon

THE FRESH-WATER LOCHS OF SCOTLAND. 313

on the date of the survey the sun could not be seen, except by going
over to the north-west shore. The two lochs trend in a north-east and
south-west direction, and together have a total length of 4f miles.
Loch a' Bhealaich exceeds 1| miles in length, with a maximum breadth
of a quarter of a mile. Its waters cover an area of about 175 acres,
or over a quarter of a square mile, and it drains an area of nearly 6
square miles. The maximum depth of 80 feet was observed towards
the north-east end of the loch. The volume of water is estimated at
238 million cubic feet, and the mean depth at over 31 feet. The loch
was surveyed on October 17, 1902, when the elevation of the lake-
surface was found to be 572-2 feet above sea-level. The water might
rise 2 or 3 feet above, and fall about 1J feet below, that level.

The main body of Loch a' Bhealaich is quite simple in conformation,
but at the north-east end there is a small expansion of the loch, having
a maximum depth of 14 feet, separated from the main body by a
constriction in which the depth is 9 feet. The 25-feet area is over a
mile, and the 50-feet area over half a mile, in length, the deeper water
being contained in the north-eastern half of the loch, the deepest
sounding in 80 feet having been taken about a quarter of a mile from
the north-eastern shore. The areas between the contour-lines and the
percenta ges to the total area of the loch are as follows : —

0 to 25 feet 77 jlpfes 44 per cent.

25 „ 50 „ 69*7, 39 „

Over 50 „ 29 „ 17 „

175 , 100

Temperature observations taken in the deepest part of the loch
gave 48°-9 Fahr. at the surface and at 40 feet, a reading at 76 feet
giving 48°'4.

Loch Coir' an Fhedrna (see Plate LXXIII.). — Loch Coir' an Fhearna
(or Corr, or a-Choire) is a fine sheet of water, well wooded along the
south-eastern shore, the Duke of Sutherland's lodge standing at the
lower (north-eastern) end. It is over 3 miles in length, and compara-
tively uniform in breadth, the maximum breadth being half a mile,
and the mean breadth over one-third of a mile. Its waters cover an
area of about 737 acres (considerably over 1 square mile), and it drains
directly an area of about 18J square miles, but since it receives the
outflow from Loch a' Bhealaich, its total drainage area is about 24J
square miles. The maximum depth of 151 feet was observed com-
paratively near the south-west end. The volume of water is estimated
at 1886 millions of cubic feet, and the mean depth at nearly 59 feet.
The loch was surveyed on October 15 to 17, 1902; the elevation of
the lake-surface on commencing the survey on the 15th was found to

314 BATHYMETRICAL SURVEY OP

be 569*7 feet above sea-level, but the water rose to the extent of
9 inches by the 17th, when Loch a' Bhealaich was surveyed. On the
15th the water was about its lowest level, and might rise 2 or 3 feet.
Loch Coir an Fhearna is quite simple in conformation, with the
deeper water lying towards the south-west end — that is, towards the
peninsula separating it from Loch a' Bhealaich, and the fact that in
Loch a' Bhealaich the deeper water also approaches the separating
peninsula seems to suggest that the two lochs may at one time have
been continuous. The contour-lines all enclose continuous areas,
approaching much nearer to the south-west than to the north-east
end, indicating a more gentle slope towards the north-east. Thus
the 100-feet area is distant about three-quarters of a mile from the
north-east end, but approaching to within less than a quarter of a
mile from the south-west end, and the maximum depth of 151 feet
was observed about half a mile from the south-west end. The slope
along the south-east shore is as a rule steeper than along the opposite
shore, and this is especially the case off Creag Chraobhach, at the
position of the deepest sounding, where a sounding in 46 feet was
taken about 50 feet from the shore. This is shown in cross-section G-H
on the map. The areas between the contour-lines at intervals of
50 feet, and the percentages to the total area of the loch, are as
follows : —

0 to 50 feet 343 acres 46 '6 per cent.

50,, 100 „ 269 „ 36-5

100,, 150 „ 124 „ 16-8

Over 150 , 1 O'l

737 ,, 100-0

Temperature observations taken in the deepest part of the loch at
1.30 p.m. on October 16, 1902, gave readings of 50°-0 Fahr. at the
surface, at 20 feet, and at 80 feet, and a reading of 49°-8 at 130 feet.

Loch Syr e (see Plate LXXIV.). — Loch Syre lies about 3£ miles to
the north of the east end of Loch Naver, on the high ground between
Strath Naver and Loch Laoghal, the last-named loch being only about
1£ miles distant to the west. It is an irregular shallow loch, with
several islands in it, and the eastern part is full of stones. From east
to west it has a length of nearly three -quarters of a mile, with a
maximum breadth of over half a mile. Its waters cover an area of about
106 acres, and it drains an area of over 5 square miles. The maximum
depth of 12 feet was observed in the south-eastern part of the loch.
The volume of water is estimated at 25 million cubic feet, and the
mean depth at 5J feet. The loch was surveyed on October 1, 1902,
when the elevation of the lake-surface was found to be 412-8 feet above
the sea; when levelled by the officers of the Ordnance Survey on

THE FRESH-WATER LOCHS OF SCOTLAND. 315

July 23, 1870, the elevation was 411-4 feet above sea-level. The level
of the loch has been raised over a foot by means of a dam above the
first island, and it was proposed to raise it still further to the extent of
2 or 3 feet. At the time of the survey the highest drift-mark observed
was about 2 feet above the water, which might fall about a foot.

The floor of Loch Syre is irregular, as might be expected from its
extremely irregular outline and many islands. The deepest water was
found in the south-eastern angle of the loch, where there is a small
area over 10 feet in depth, the deepest cast in 12 feet having been
taken about 100 yards from the eastern shore and 150 yards from the
southern shore. Between the deepest sounding and the southern shore
the bottom rises to 9 feet and sinks again to 11 feet close inshore.
The area of the lake-floor covered by less than 10 feet of water is about
97 acres, or 92 per cent, of the entire area of the loch. The temperature
of the surface water on the date of the survey was 540<7 Fahr.

316 BATHYMETRICAL SURVEY OF

LOCHS OF THE BOUGIE BASIN.

THE three lochs to be dealt with here form a connected series, the
overflow from Loch Cuil na Sithe being carried into Loch Laoghal by
the Lbn Achadh na h-Aibhne, while Lochs Laoghal and Creagach are
almost continuous, the connecting stream being only about 200 yards
in length. Of the total area of the basin (about 62 square miles), about
35 square miles, or 56 per cent., drain into these three lochs.

Loch Cbil na Sithe (see Plate LXXIV.).— Loch Cuil na Sithe (or
Coulside) is a small narrow loch lying over a mile to the west of the head
of Loch Laoghal, and about 5 miles to the north of Altnaharra, at the
head of Loch Naver. It trends east-north-east and west-south-west,
and is very nearly a mile in length, varying little in width, the
maximum breadth being about 250 yards. Its waters cover an area
of about 58 acres, and it receives the drainage from a comparatively
large tract of country, the drainage area being about 9 square miles —
an area a hundred times greater than that of the loch. The maximum
depth of 14 feet was observed in two places near the middle of the
loch. The volume of water is estimated at 19 million cubic feet, and
the mean depth at 7J feet. The loch was surveyed on September 29,
1902, but the elevation of the lake-surface above the sea could not be
determined; a drift-mark was observed over 6 feet above the water,
which might fall to the extent of a foot, giving a range in level
exceeding 7 feet.

Loch Cuil na Sithe is extremely simple in conformation, and com-
paratively uniform in depth. The upper portion is being silted up,
and is occupied by weeds, and the lower portion is full of stones. The
10-feet contour coincides approximately with the outline of the loch,
and encloses an area of about 20 acres, or 35 per cent, of the total
area of the loch. The temperature of the surface water on the date of
the survey was 56°-2 Fahr., and a reading at a depth of 11 feet gave
53°-9.

Loch Laoghal (see Plate LXXV.). — Loch Laoghal (or Loyal) is
distant about 4| miles from Tongue and about 6 miles from Altnaharra,
the road between these two places running alongside the western shore
of the loch throughout its whole length. To the west rises Ben Loyal,

THE FRESH- WATER LOCHS OF SCOTLAND. 317

one of the most beautiful of mountains, with picturesque outline, the
highest point exceeding 2500 feet; beyond Leitirmhor the granite is
being quarried for building purposes, leaving a great scar on the
hillside. To the east of the northern portion of the loch rises Beinn's
Tomaine (Ben Stomino) to a height of 1728 feet, along the base of
which the shore of the loch is thickly wooded. In outline the loch
resembles somewhat a Wellington boot, with the toe pointing in a
westerly direction, while the body of the loch trends almost north
and south. The loch is 4£ miles in length, with a maximum breadth
of nearly a mile, the mean breadth exceeding half a mile. The waters
of the loch cover an area of about 1630 acres, or over 2| square miles,
and it drains directly an area of over 24 square miles, but since it
receives the overflow from Loch Cuil na Sithe, its total drainage area
exceeds 33 square miles. The maximum depth of 217 feet was
observed near the foot of the loch, little more than half a mile from
the northern shore. The volume of water contained in the loch is
estimated at 4628 millions of cubic feet, and the mean depth at 65J
feet. The loch was surveyed on September 26 to 29, 1902, and the
elevation of the lake-surface 011 commencing the survey was found,
by levelling from bench-mark, to be 369-9 feet above the sea; when
levelled by the officers of the Ordnance Survey on August 29, 1870,
the elevation was found to be 369'2 feet above sea-level. The highest
drift-mark observed was 2J feet above the surface of the water at the
time of the survey, and it was stated that the water might fall to
the extent of a foot.

Loch Laoghal contains two deep basins, the larger and deeper in
the northern portion of the loch, and the smaller and shallower
towards the head of the loch, separated by a shoaling of the bottom
about 2^ miles from the foot of the loch, where there is a slight
constriction in the outline. The 50-feet con tour-line is continuous, and
encloses an area about 4 miles in length, extending from quite close
to the northern end to within half a mile from the south-western end.
There are two 100-feet basins : the smaller one approaches to within
less than a mile from the head of the loch, and is three-quarters of a
mile in length, the maximum depth observed therein being 137 feet,
about 1J miles from the south-west end; the larger one is over 2 miles
in length, and approaches to within about 250 yards from the northern
end, enclosing the deepest part of the loch. The 1 50-feet area is about
1J miles in length, and distant about a quarter of a mile from the
northern end. The 200-feet area is nearly three-quarters of a mile in
length, distant less than half a mile from the northern end. The
longitudinal section on the map shows how rapidly the water deepens
on proceeding from the northern end along the central line of the loch,
while the opposite end of the loch is comparatively shallow and the
slope of the bottom there gentle; it also shows the considerable rise

318

BATHYMETRICAL SURVRY OP

of the bottom between the two deep basins. The cross-section G-H
is taken at the position of the deepest sounding, and shows a slight
rise of the bottom off the western shore from 80 to 75 feet. This
section shows a steep offshore slope at both sides of the loch, but more
especially off the eastern shore, where a sounding in 78 feet was taken
about 80 feet from shore, and this steep slope off the eastern shore
is continued to the northward, where a sounding in 48 feet was taken
about 60 feet from shore. The soundings taken on the rise between the
two deep basins indicate a rather uneven floor; for instance, one line
of soundings from west to east shows that the bottom sinks gradually
from the western shore to 86 feet, then rises to 60 feet, sinks to
75 feet, rises to 30 feet, sinks slightly again to 32 feet, and then rises
towards the eastern shore ; a little farther south a sounding was taken
in 40 feet between two deeper soundings (54 and 57 feet).

The following table gives the approximate areas between the
consecutive contour-lines, and the percentages to the total area of
the loch : —

Oto 50 feet
50,, 100 „
100,, 150 ,,
150,, 200 ,,
Over 200 ,

612 acres
522 „
246 „
200 „
49 „

1629 ,

38 per cent.
32 „
15 „
12 „
3 „

100

Temperature Observations. — Many observations of the temperature
of the surface water in Loch Laoghal were taken on September 26, 27,
and 29, 1902, and two serial temperatures were taken on September 29,
one in each of the two deep basins. The surface temperature varied
from 52°-5 to 53°'6 Fahr. The serials gave the following results : —

Depth in feet.

Deepest part of Jocli.
Sept. 29, 1902,
noon.

Southern deep basin.
Sept. 29, 1902,
2 p.m.

0 Fahr.

0 Fahr.

0

53-0

53-6

10

52-5

53-4

15

52-4

20

52-5

25

52-5

52:9

27-5

52-6

30

53-6

35

...

52-2

40

524

50

52:5

52-4

70

524

52-3

100

52-4

52-5

125

50-9

135

47-8

52-3

145

46-7

...

150

46-5

195

46-1

...

THE FRESH-WATER LOCHS OF SCOTLAND. 319

These observations show an extreme range throughout the loch
amounting to 7°'5, but the greater part of this range was observed
beyond the depth of 100 feet in the deepest part of the loch, the range
from the surface down to 100 feet not exceeding l°-4. In the southern
shallower basin the temperature varied little down to the bottom in
135 feet, there being no decrease in temperature beyond 100 feet,
whereas at a depth of 135 feet in the northern deeper basin the tem-
perature was 40>5 lower than at a similar depth in the southern basin,
and the temperature at the bottom of the deeper basin was 6° lower
than anything observed in the shallower basin.

Loch Creagach (see Plate LXXV.). — Loch Creagach (or Craggie) lies
immediately to the north of Loch Laoghal and at the same level, the
short stream between them having a slight current flowing from Loch
Laoghal into Loch Creagach. At the north end of Loch Creagach there
is a small expansion of the outflowing river, called Loch Slaim (or
Slam), which was not sounded. The general trend of Loch Creagach is
nearly north and south, with a slight bend in the outline, the northern
portion running towards the north-east. It is over 1J miles in length,
with a maximum width in the southern portion of half a mile. Its
waters cover an area of nearly 300 acres, or nearly half a square mile,
and it drains directly an area of 1| square miles; but since it receives
the outflow from Lochs Laoghal and Ciiil na Sithe, its total drainage
area is nearly 35 square miles. The maximum depth of 84 feet was
observed near the middle of the loch. The volume of water is estimated
at 429 million cubic feet, and the mean depth at 33 feet. The loch
was surveyed 011 September 27, 1902, when the elevation of the lake-
surface was found to be identical with that of Loch Laoghal, viz. 369'9
feet above the sea; when levelled by the Ordnance Survey officers on
August 27, 1870, the elevation was 369-2 feet above sea-level, as in
the case of Loch Laoghal.

Loch Creagach resembles Loch Laoghal in that it contains two deep
basins, which are separated by shallower water at the position of the
constriction in the outline of the loch towards the northern end. The
deeper basin occupies the wide southern portion of the loch, towards
the peninsula separating this loch from Loch Laoghal, in which also
the deeper water approaches the dividing peninsula, suggesting that
at one time the two lochs may have formed a continuous sheet of water.
The principal 50-feet area is about three-quarters of a mile in length,
distant less than a quarter of a mile from the southern end of the loch.
Within this basin there is a small elevation covered by 47 feet of water
in the widest part of the loch towards the eastern shore. The maximum
depth of the loch (84 feet) occurs a short distance to the north of this
elevation, and about three-quarters of a mile from both ends, but
towards the western shore, as will be seen in cross-section C-D on the

320 BATHYMETRICAL SURVEY OF

map. Towards the northern end of the loch lies the second 50-feet area,
based on soundings of 50 and 51 feet, and of small extent, the greatest
depth recorded on the ridge separating the two deep basins being
20 feet close to the eastern shore. The contour of the bottom is shown
in the longitudinal section A-B on the map. The areas between the
consecutive contour-lines, and the percentages to the total area of the
loch, are as follows: —

0 to 25 feet 138 acres

25,, 50 „ 78 „

50,, 75 „ 74 „
Over 75 „ 7 „

297 „ 100-0

The temperature of the surface water on the date of the survey was
54° Fahr., and four readings beneath the surface in the deepest part of
the loch gave identical results, viz. 53° at depths of 10, 25, 50, and
70 feet.

THE FRESH- WATER LOCHS OF SCOTLAND. 321

LOCHS OF THE KINLOCH BASIN.

THERE are two lochs to be dealt with here, viz. Loch Chaluim and
Loch an Dithreibh, the superfluent waters of which are carried into
the Kyle of Tongue by the Amhainn Ceann Locha (or Kinloch river).
Loch Chaluim is the only one of several small lochs in the basin which
could be sounded, and it flows by the Allt an Dithreibh into Loch an
Dithreibh. The two lochs form a complete contrast in outline and
conformation of the bottom.

Loch Chaluim (see Plate LXXVI.). — Loch Chaluim lies on the
south-western flank of Beiun Laoghal, little more than a mile from Loch
Cuil na Sithe in the Borgie basin. It is most irregular in outline and
in conformation, with one comparatively large island, and with weeds
obstructing many of the bays. Measured in a south-west and north-
east direction, it is about three-quarters of a mile in length, with a
maximum breadth of half a mile, its waters covering an area of about
96 acres. The maximum depth of 30 feet was observed in the extreme
western portion of the loch, the mean depth being estimated at 8 feet,
and the volume of water at 33 million cubic feet. The loch was
surveyed on September 29, 1902, but the elevation of the lake-surface
above the sea could not be determined.

Loch Chaluim is on the whole shallow, only three soundings exceed-
ing 20 feet having been recorded in the most westerly expansion of the
loch. There are two 10-feet basins, the principal one extending from
the extreme west end of the loch to beyond the island, filling up the
south-western expansion of the loch to the south of the island, and
enclosing the deepest part of the loch, the smaller one lying in the
eastern and south-eastern expansions of the loch, and having a maximum
depth of 17 feet. The greater part of the lake-floor is covered by less
than 10 feet of water, equal to about 69 acres, or 72 per cent, of the
total area.

Temperature Observations. — A series of temperatures was taken in
the deepest part of the loch, with the following results : —

322 BATHYMETRICAL SURVEY OF

Surface •. 55°'8 Fahr.

2 feet 55°-7 „

3 „ 55°*4 „

3-5,, 55°'2 „

4 53°-6 „

5 „ 53°'4 „

10 „ 53°-0 ,,

20 „ 53°'l ,,

This series shows a range of 20>8, there being a fall of no less than
l°-6 between 3J and 4 feet.

Loch an Dithreibh (see Plate LXXVL). — Loch an Dithreibh (or
Deerie, or Derry) lies less than 3 miles to the south of the head of the
Kyle of Tongue, with Ben Loyal to the east and the lofty Ben Hope, a
magnificent object in the landscape, to the west. The general trend
of the loch is north-north-east and south-south-west, the main body
of the loch trending almost north and south, and throwing out an arm
towards the north-east. The loch is over l£ miles in length, the main
body being approximately uniform in width, with a maximum breadth
of two-thirds of a mile, while the north-eastern arm is much narrower ;
the mean breadth of the entire loch is nearly half a mile. Its waters
cover an area of about 475 acres, or three-quarters of a square mile,
and it drains directly an area of 10 square miles; but since it receives
the overflow from Loch Chaluim, its total drainage area is 12f square
miles. The maximum depth of 157 feet was observed approximately
near the centre of the main body of the loch. The volume of water
is estimated at 1366 million cubic feet, and the mean depth at 66 feet.
The loch was surveyed on October 1, 1902, when the elevation of the
lake-surface was found, by levelling from bench-mark, to be 267*45
feet above the sea ; when levelled by the officers of the Ordnance Survey
on October 26, 1870, the elevation was 267*8 feet above sea-level.

Loch an Dithreibh includes two basins — (1) a larger deep basin in
the main body of the loch, and (2) a smaller shallower basin in the
north-eastern arm, separated by a rise of the bottom on which the
deepest sounding was 49" feet. The maximum depth observed in
the small subsidiary basin was 59 feet, and the separating ridge is
irregular, for a sounding in 21 feet was taken in its central part
surrounded by deeper water. The 25-feet contour-line is continuous
from end to end of the loch, coinciding approximately with the outline
of the loch, but approaching close to the eastern shore off Creag an
Dithreibh and Creag na Luath-ghaire. The 50-feet area is cut into
two portions, as already indicated, the main portion approaching close
to the southern end of the loch and exceeding 1 mile in length. The
75-feet area is nearly a mile in length, and at its northern border the
lake-floor shows conspicuous undulations, giving to the 75-feet contour-

THE FRESH- WATER LOCHS OF SCOTLAND. 323

line a strikingly sinuous character. The 100-feet area has a length
of three-quarters of a mile, approaching comparatively very close to
the southern shore, where a sounding in 115 feet was recorded about
150 yards off shore. The 125-feet area exceeds half a mile in length,
and the small 150-feet area, based upon soundings of 151, 152, and 157
feet, occupies an approximately central position. Along the eastern
shore the slope of the bottom is in places very steep. Off Creag na
Luath-ghaire a sounding of 40 feet was taken about 80 feet off shore,
and another so'unding in 49 feet about 70 feet off shore, while off Creag
an Dithreibh one sounding was taken in 65 feet about 100 feet off shore,
and another sounding in 65 feet about 60 feet off shore. This last-
mentioned sounding gives an angle of slope exceeding 45°, the fall
exceeding 1 foot per foot. The areas between the consecutive contour-
lines at equal intervals, and the percentages to the total area of the
loch, are as follows: —

0 to 50 feet 204 acres 42*9 per cent.

50,, 100 „ 150 „ 31-4

100,, 150 „ 113 „ 23-9

Over 150 . 9 , 1'8

476 ,, 100-0

Temperature Observations, — A series of temperatures taken in the
deepest part of the loch on the date of the survey gave the following
results : —

Surface 54°'0 Fahr.

25 feet 53°'5

50 „ 53°-0

100 „ 52°-5

125 „ - ... 48°-6

145 „ 48°-4

This series shows a range of 5°'6 from surface to bottom, the greatest
fall of temperature occurring beyond the depth of 100 feet — a fall
equal to about 4° between 100 and 125 feet.

324 BATHYMETRICAL SURVEY OF

LOCHS OF THE HOPE BASIN.

THE only loch to be dealt with here is the large Loch Hope, one
of the most important and the most northerly of the Sutherlandshire
lochs. There are several small hill lochs within the basin, which
could not be sounded at the time of the visit of the Lake Survey.
The headwaters of the basin take their rise on the flanks of Ben Hee,
of Meallan Liath, and of Meall Horn, whose summits attain heights
exceeding 2500 feet. The total area of the basin is 75 square miles,
of which nearly the whole drains into Loch Hope.

Loch Hope (see Plate LXXVII.). — Loch Hope lies close to the eastern
shore of Loch Eriboll on the north coast of Scotland, at an elevation
of only 12 \ feet above sea-level, so that a slight subsidence would
convert it into an arm of the sea and a branch of Loch Eriboll. The
natives declare that the sea never enters the loch, though ordinary
spring tides attain a point not more than half a mile from the foot
of the loch, and at the upper end three terraces are to be seen, and
traces perhaps of a fourth. Ben Hope rises very steeply to a height
of over 3000 feet to the south-east of the head of the loch, and the
ground further north and to the west, though not so high, is also
steep close to the shore; some parts of the shores are well wooded.
The loch is free from islands, but on the date of the survey a reputed
old castle was just showing a few inches above the water about a mile
from the foot of the loch. The trend of the loch is almost north and
south, and the total length exceeds 6 miles. The two ends of the loch
are narrow, but it broadens out in the central portion, where there is
a maximum breadth of three-quarters of a mile; the mean breadth
of the entire loch is over one-third of a mile. The waters of the loch
cover an area exceeding 1500 acres, or 2J square miles, and it drains
an area exceeding 73 square miles. The maximum depth of 187 feet
was observed about midway between the two ends of the loch. The
volume of water is estimated at 4032 millions of cubic feet, and the
mean depth at 61^ feet. The loch was surveyed on September 30, 1902,
when the elevation of the lake-surface was found, by levelling from
bench-mark, to be 12-55 feet above the sea; when levelled by the
officers of the Ordnance Survey on August 9, 1858, the elevation was

THE FRESH- WATER LOCHS OF SCOTLAND. 325

12'3 feet above sea-level. The highest drift-mark observed was 9 feet
above the surface of the water on the date of the survey, and, according
to the local ghillie, the water might fall 2 feet lower, giving a total
range in level of about 11 feet.

The floor of Loch Hope is somewhat uneven. Proceeding from the
lower (northern) end of the loch for a quarter of a mile, one meets with
a small 25-feet area, based on soundings of 26, 30, and 32 feet, whence
the bottom rises in the vicinity of the reputed old castle already
mentioned, which lies toward the eastern shore ; off the opposite shore
in this locality there were many boulders in the water. Thence pro-
ceeding to the southwards, the water rapidly deepens until it attains
a depth of 104 feet opposite the entrance of the Allt an Ruighein,
about 1J miles from the foot of the loch. Thence for a distance of
about three-quarters of a mile the bottom rises again until the depth
in the centre is 44 feet, with deeper water on both sides. This shoal
coincides with a narrowing in the outline of the loch, whence to the
south the loch broadens out and the water deepens so rapidly that at
a distance of little more than half a mile from the 44-feet sounding the
maximum depth of the loch (187 feet) is met with. A section across
the loch in the position of the deepest sounding is shown in cross-
section C-D on the map. From this position the bottom rises gradually,
though irregularly, towards the head of the loch. A section down the
centre of the loch along the axis of maximum depth is shown in
longitudinal section A-B on the map, which brings out the salient
features in the conformation of the lake-floor, but gives no indication
of some of the minor irregularities. For instance, the 44-feet shoal
already referred to is not shown because a depth of 56 feet occurs
nearer the western shore, nor another shoaling covered by 117 feet of
water to the south of the deepest sounding. The offshore slope is in
some places rather steep — for instance, along the eastern shore, where
off the entrance of the Allt a' Mhuilinn a sounding in 53 feet was taken
about 60 feet from shore, and off the entrance of the Allt a' Phris Ghil
a sounding in 28 feet was taken about 30 feet from shore ; also along
the western shore about 1J miles from the head of the loch, where a
sounding in 25 feet was taken about 30 feet from shore. The following
table gives the approximate areas between the contour-lines at equal
intervals, and the percentages to the total area of the loch : —

Oto 50 feet 723 acres

50,, 100 „ .474 „
100,, 150 „ 218 „

Over 150 , 91

1506 , 100-0

Temperature Observations. — A series of temperatures was taken at

326

BATHYMETRICAL SURVEY OF

PQ

Ill

III

III

•Ml

& a

loll

above
Fee

CO CO ^H

Cft O5

s

•8*3

11
II

"o-S

•STJ
is

II

S bo

SI

Jo

If

•*J

3-s

!l

*%

THE FRESH- WATER LOCHS OF SCOTLAND. 327

3 p.m. on the date of the survey in the deepest part of the loch, with
the following results : —

Surface 54°'6 Fahr.

5 feet 54°-6

10 .„ 54°-5

25 ,, 54°-2

50 ,, 54°-0

100 „ 53°-3

120 „ 53°'0

135 „ 52°-l

150 ,, 49°-2

This series shows a range from surface to bottom amounting to
5°*4. The upper layers of water are practically uniform in temperature,
the decrease from the surface down to 50 feet being only 00>6, down to
100 feet l°-3, and down to 120 feet l°-6, whereas between the depths
of 120 and 150 feet the fall of temperature was 3°-8. It was stated
that the loch freezes all over in winter.

The details regarding the lochs in the Naver, Borgie, Kinloch, and
Hope basins are collected together in the table on p. 326 for convenience
of reference and comparison. From this table it will be seen that in the
eleven lochs under consideration over 1400 soundings were taken, and
that the aggregate area of the water surface is over 11 square miles, so
that the average number of soundings per square mile of surface is 127.
The aggregate volume of water contained in the lochs is estimated at
about 15,600 millions of cubic feet. The area drained by these lochs
is about 239J square miles, or twenty-two times the area of the lochs.

NOTES ON THE GEOLOGY OF THE DISTRICT BETWEEN LOCH HOPE AND

STRATH NAVER.

By B. N. PEACH, LL.D., F.R.S., and J. HORNE, LL.D., F.R.S.

The district extending from Loch Hope to Strath Naver, in the
north of Sutherland, has not yet been wholly mapped by the Geological
Survey.

The north-western tract, embracing the lower part of Loch Hope,
comes within the belt of territory affected by the Post-Cambrian move-
ments to which reference has been made in the description of the geology
of the districts of Loch Assynt and Loch Maree.* Hence, on the hill-
slopes on either side of the river Hope, we find various subdivisions of

» See pp. 178 and 233.

328 BATHYMETRICAL SURVEY OF

the Cambrian system, repeated by folds and reversed faults, and overlaid
by slices of Archaean gneiss, which resemble portions of the old floor on
which the Cambrian strata rest unconformably west of Loch Eriboll and
the Kyle of Durness.

East of these displaced masses there is a great succession of crystalline
schists stretching eastwards to Strath Naver, which, in the north of
Sutherland, are everywhere separated from the rocks to the west by a
powerful line of disruption, termed the Moine thrust. They consist
of two main types — flaggy quartzose granulites and garnetiferous
muscovite-biotite schists with intermediate varieties — the whole
evidently representing an altered sedimentary series. Bands of
garnetiferous hornblende-schist are intercalated in these granulitic
schists, which are, without doubt, deformed intrusive sheets of igneous
material. The lithological characters of the strata, the order of succes-
sion, and the peculiar system of folding are magnificently displayed
on Ben Hope (3040 feet), where the divisional planes generally dip to
the east-south-east at angles varying from 12° to 30°. But in addition
to these members of the Moine series, which are now generally regarded
as altered sediments, there are belts of massive, hornblendic, and
micaceous gneisses resembling the Lewisian types in the north-west of
Sutherland. The precise relationship of these two divisions of the
crystalline schists has not been definitely ascertained in this district,
but it is sufficiently clear that they have been affected by a common
system of folding, and in certain localities by common planes of
schistosity. From the north coast, these massive basic and acid gneisses
of Archaean type stretch southwards along the west side of the Borgie
valley to Loch Creagach, near Loch Laoghal, and another belt of
somewhat similar materials has been traced from the village of Tongue
northwards by Ribigill to Loch an Dithreibh.

After the eastern schists had assumed their present crystalline
characters, they were pierced by intrusive masses of granite, which
form a picturesque group of peaks on Beinn Laoghal, south of Tongue.
The mapping of that area leads to the conclusion that the granite there
forms a great sill-like intrusion, which, on the north-east side of the
loch of that name, branches off into minor sheets, or apophyses.

On the east side of the Kyle of Tongue there are various small
outliers of Old Red Sandstone, largely composed of conglomerate, as,
for instance on Cnoc Creagach, on Beinn Bhreac, and on Cnoc an
Fhreiceadain, which rest unconformably on the crystalline schists.
They contain fragments of the various component members of the
underlying platform, together with blocks of Cambrian quartzite and
limestone.

Loch Hope. — The lower portion of this lake, measuring about 2 miles
in length, is floored by thrust masses of Lewisian gneiss and deformed
schistose rocks affected by the Post-Cambrian movements, while the

THE FRESH-WATER LOCHS OF SCOTLAND. 329

lip of the basin, above the point where the loch discharges into the
river Hope, is composed of Lewisian gneiss on the east side and
Cambrian quartzites on the west. No rock is visible at the mouth of
the lake, nor in the course of the stream that connects it with the sea.
On either side of the river Hope there are alluvial terraces, eroded
partly out of solid rock and partly out of raised beach deposits. There
are the remains of the 100-feet beach by the river Hope, and of the
50-feet beach at the head of the lake ; hence it is evident that during
their deposition the sea must have extended far up the valley.

The lower portion of the lake lies along a line of fault trending
nearly north and south, which is evidently continued northwards along
the channel of the river Hope, though concealed by the alluvial deposits.
On either side of this line there has been a lateral shift of the outcrops
of the various groups of rock, indicating a downthrow to the east. This
dislocation has been proved to traverse that portion of land that juts
into the loch on the west side about a mile south of Poll Ath-roinn,
where the quartzose flagstones of the Moiiie series have been thrown
down against a narrow belt of deformed Lewisian gneiss. Though the
whole of Strath Mor (the valley above Loch Hope) has not been mapped
by the Geological Survey, it is not improbable, judging from the straight
feature, that the fault may be prolonged southwards, and may have
been a prominent factor in determining the original course of the valley.

Though no rock is seen at the outlet of the lake, it is not improbable
that it may be a rock basin. Its widest and deepest part lies within
the area occupied by the eastern or Moine schists (Geological Survey),
just above the belts of displaced and deformed Lewisian gneisses and
the crushed schistose rocks in association with them. Bounded by the
75-feet contour-line, this upper basin extends for 1| miles above the
narrows, with an average breadth of one-third of a mile. A second
basin, with a maximum depth of 104 feet, occurs further down, opposite
Poll Ath-roinn, which is carved out of a belt of Lewisian gneiss and
the mylonized rocks above the Moine thrust-plane.

As the surface of the water in Loch Hope is only 12 feet above sea-
level, the greater part of the lake is below the level of the sea.

The striae and the distribution of the drift indicate that during the
early and later glaciatioiis the ice moved from the south towards the
north, so that the trend of the lake coincides generally with the
direction of ice-movement.

Loch Laoghal, Loch Creagach, and Loch Slaim. — The rocks under-
lying this chain of lochs consist of hornblendic gneisses exposed on
either side of Loch Slaim, of granulitic micaceous gneisses of the Moine
series, and the granite of Beinn Laoghal and Beinn's Tomaine. Along
the northern margin of this granite mass the strike of the schists is
nearly east and west, the general dip of the foliation planes being
towards the south at angles varying from 20° to 70°. These rocks are

330 BATHYMETRICAL SURVEY OF

visible at certain localities on either side of Loch Creagach, and on the
ridges east and west of the lower end of Loch Laoghal, where they pass
underneath the sill-like mass of granite and its apophyses. For a
distance of upwards of 2 miles from the foot of Loch Laoghal granite
occurs on both banks of the lake, but in the southern portion the
granite extends continuously along the west side, while the crystalline
schists occur at intervals on the east side.

Though these three lakes are now separated from each other, they
may be regarded as one sheet of water, as they are nearly at the same
level. The strip between Loch Slaim and Loch Creagach consists partly
of moraine matter and partly of the same material arranged in the
form of terraces rising to about the 400-feet contour-line. The barrier
between Lochs Creagach and Laoghal is composed partly of terraced
morainic matter, partly of alluvium brought down by the stream
draining the north slope of Beinn's Tomaine, and partly of gravelly
material driven along the spit by the prevalent west wind.

An alluvial terrace, about the 400-feet level, connects the three
lakes, thereby indicating that they must have been at one time con-
tinuous. This feature does not occur in the upper part of Loch Laoghal,
where the unmodified moraines extend downwards to the present shore
of the loch. It is not improbable, therefore, that the upper portion may
have been occupied by a glacier while the barrier of moraines beyond
Loch Slaim was being lowered.

But though these lakes are ponded back by moraines at the surface,
it would appear that the lower portions of Loch Creagach and Loch
Laoghal may be rock basins, for at a distance of about 1J miles below
Loch Slaim the river Borgie flows over a rocky floor of hornblendic
gneiss at a height of 304 feet, while the surface level of the two upper
lochs is 369 feet. The difference between these elevations is 65 feet.
On referring to the chart of the soundings, it will be seen that the
greatest depth of Loch Creagach is 84 feet, of the lower basin of Loch
Laoghal 217 feet, and of the upper basin 137 feet. If, then, we assume
that the rocky barrier 1J miles below Loch Slaim, near Dailaneas,
crosses the valley at the same level (304 feet) underneath the drift,
then it follows that the depth of water below the rocky barrier is in
the case of Loch Creagach 19 feet, of the lower basin of Loch Laoghal
152 feet, and of the upper basin 72 feet. The deepest part of Loch
Laoghal occurs where the valley is most constricted, and where the
hills on either side are loftiest.

Although no glacial markings have been found in the immediate
neighbourhood of the lochs, the striae in the surrounding district show
that the ice-movement during the period of maximum glaciation was
slightly west of north. The dispersal of the boulders and the disposition
of the moraines indicate that during the later glaciation a confluent
glacier moved northwards from the interior, one branch skirting the

THE FRESH-WATER LOCHS OF SCOTLAND. 331

western slope of Beinu Laoghal, a second passing through the hollow
occupied by the loch of that name, and a third round the eastern slope
of Benin's Tomaine. The stages in the gradual retreat of the mass of
ice that moved down the valley of Loch Laoghal are clearly marked by
a succession of moraine terraces, which enclose the small lochans shown
on the chart to the east of Loch Creagach and Loch Slaim.

Loch an Dithreibh is a rock basin lying in hornblendic and micaceous
gneisses, whose strike is nearly north and south and nearly parallel to
the direction of the lake. They are admirably exposed on the great crag
on the east side of the loch. The solid rock is not exposed at the lip
of the basin, but at a point in the stream about a quarter of a mile below
the outlet at a height of 261 feet, the surface of the loch being 267 feet
above sea-level, and the deepest part of the basin being 157 feet.

Loch Syre, like many of the lochans east of Loch Laoghal, is sur-
rounded with morainic deposits.

NOTES ON THE BIOLOGY OF THE LOCHS OF NORTH SUTHERLANDSHIRE.
By JAMES MURRAY.

Tow-nettings were taken in seven of the lochs. These include three
deep lochs (Hope, an Dithreibh, and Laoghal), two very shallow lochs
(Chaluim and na Meide), while Loch Naver is intermediate. The
biological phenomena are in accordance with those differences, the
plankton of the deep lakes being relatively poor, and similar to that of
great lakes in general, the shallow lakes having a large admixture of
littoral forms.

All the lochs were rich in algae, especially Desmids, including many
of those conspicuous species of western type, alluded to by Messrs.
West, which are so characteristic of the extreme north-western fringe
of Europe. The northern species of Diaptomus — D. laciniatus, D.
laticeps, and D. Wierzejskii — which are so widely distributed in the
north of Scotland, Orkney, Shetland, and the western isles, and which
are common in many lochs immediately adjacent, both to the east and
south, are absent from most of the lochs of this district. D. laticeps
is in Lochs na Meide and Naver, D. laciniatus in Loch na Meide only.
D. gracilis is in six of the lochs, and in five it is the only species.

In the short lists of organisms following the name of each loch,
species of general distribution are omitted, only those being included
which are interesting on account of their distribution or rarity.

Loch Hope. — Leptodora, Daphnia hyalina (head rounded), Dia-
phanotsuma, Fluscularia pelayica, Triarthra lonyiseta, Clathrulina

332 BATHYMETRICAL SURVEY OF

elegans, Micr aster ias furcata, Staurastrum furcigerum, Xanthidium
subhastiferum.

Loch an Dithreibh. — Bosmina obtusirostris, var. longispina, Flos-
cularia pelagica, Staurastrum ophiura, cysts of Ceratium. Animal
life (both as to individuals and species) was very scarce, while the
smaller algae were conspicuous.

Loch na Meide. — Diaptomus laticeps, D. laciniatus, Cyclops gigas,
Daphnia (galeate), Ilyocryptus acutifrons, Gastropus stylifer ( = Notops
pygmceus), Staurastrum ophiura, S. arctiscon, 8. pseudopelagicum,
Micr aster ias apiculata, var. fimbriata. This loch was remarkable for
the abundance of both animal and plant life ; about eighty species of
organisms were found in the first cursory examination. The true
plankton was not, however, particularly rich, there being a very large
admixture of littoral species. Ilyocryptus acutifrons was first observed
in Scotland in this loch, though it was afterwards found that it had been
collected in Loch Shin at an earlier date.

Loch Naver. — Diaptomus laticeps, Bosmina obtusirostris (small, with
long spine), Floscularia pelagica, Gastropus stylifer, Staurastrum
ophiura, S. arctiscon, S. grande, Micrasterias conferta, M. furcata
(typical, also a variety having the whole surface covered with hemis-
pherical papillae of unequal sizes).

Loch Chaluim. — Daphnia (two forms, first with small rounded head,
second with very large broad, depressed head, many males), Syncluzta
pectinata, Gastropus stylifer, Polychcetus collinsi, Staurastrum ophiura,
S. arctiscon, S. furcigerum.

Loch Laoghal. — Bosmina obtusirostris, var. longispina, Floscularia
pelagica, Triarthra longiseta, Clathrulina elegans, Staurastrum pseudo-
pelagicum, S. jaculiferum.

Loch Creagach is connected with Loch Laoghal by a wide channel,
and stands at the same level. The biology calls for no separate mention.

NOTE ON Clathrulina elegans, Cienk. — Skeletons of this animal were
abundant in the deep lochs Hope and Laoghal. In an earlier paper*
an attempt was made to account for the presence of these empty shells
in so many of the Scottish lochs, and as a general rule only in large
ones, on the supposition that they were derived from the shallow waters
in which C '. elegans is known to live, attached to water-plants by a
slender stalk. Up till quite recently only empty cases had been found,
or at most an occasional shell containing an encysted mass of protoplasm,
and on these facts was based the suggestion put forward as to their
origin. A fresh aspect is put upon the inquiry by the recent observation
that in Loch Lochy, where the animal was abundant in August, 1905,
when the loch was visited in company of Prof. Bachmann, most of the
shells contained living animals, which extended their pseudopodia and

* See p. 291.

THE FRESH- WATER LOCHS OF SCOTLAND. 333

seemed quite at home. There was in no instance any trace of a stalk.
These facts led to the supposition that perhaps the lacustrine form may
be a permanent pelagic race, or even a distinct species. Or it may be
that the animal is attached when young, and becomes free when adult.
There are difficulties in the way of accepting either hypothesis. If it be
a true plankton form, we have to explain the absence of living animals
from so many of the Scottish lochs in which the skeletons occur, and
some of which have been examined at all seasons of the year. If it be
a littoral form, and only casual in the plankton, it is still unexplained
why the skeletons are, as a rule, only in large lakes.

334 BATHYMETRICAL SURVEY OF

LOCHS OF THE BEAULY BASIN.

THE Beauly basin is an important and extensive one, extending across
almost the entire width of Scotland, from Beauly firth on the east
coast to within about 4 miles from the shores of Loch Duich, and
about 6 miles from the shores of Loch Carron, on the west coast. The
basin is situated in a very mountainous district, many of the peaks in
the central and western part of the basin exceeding 3000 feet, and
some of them approaching 4000 feet, in height, while on proceeding
eastward towards the outlet of the basin the land becomes gradually
less elevated. On the southern boundary of the basin are Tigh Mor
(3222 feet), Sgurr nan Conbhairean (3634 feet), Garbh Leac (3673 feet),
Sgurr nan Ceathramhan (3614 feet), Ciste Dhubh (3218 feet), Cam
Fuaraloch (3241 feet), and Sgurr a' Bhealaich Dheirg (3378 feet) ; on
the western boundary Beinn Fhada (Ben Attow, 3383 feet), Sgiirr nan
Ceathreamhnan (3771 feet), Lurg Mhor (3234 feet), and Sgiirr Choin-
nich (3260 feet), on the northern boundary Sgiirr a' Chaoruinn (3452
feet), Bidean an Eoin Deirg (3430 feet), Maoile Lunndaidh (3294 feet),
Sgiirr Fhuar-Thuill (3439 feet), Sgorr a' Choir-Ghlais (3552 feet), and
Sgurr Ruadh (3254 feet) ; while in the central part of the basin are
Craig Dhubh (3102 feet), Sgiirr na Lapaich (3773 feet), An Riabhachan
(3696 feet), Beinn Fhionnlaidh (3294 feet), Mam Sodhail (Mam Soul,
3862 feet), Cam Eige (3877 feet), Tom a' Choinich (3646 feet), a
second peak named Sgurr na Lapaich (3401 feet), and Tuill Creagach
(3452 feet). Besides these heights there are many others which do
not attain the 3000-feet level. In the valleys between these chains of
mountains lie the lochs which were sounded by the Lake Survey staff.
In the most northerly valley, Glen Strath Farrar, there is the con-
nected series consisting of Lochs Calavie, an Tachdaidh, an Gead,
Monar, a' Mhuilinn, and Bunacharan ; in the central valley, Glen
Cannich, the connected series of Lochs Lungard, Mullardoch, and
Sealbhag ; and in the most southerly valley, Glen Affric, the connected
series of Lochs Affric, an Laghair, and Beinn a' Mheadhoin ; with the
isolated Loch na Beinne Baine as an outlier situated towards the head
of Strath Glass. These valleys all trend in a more or less east-and-
west direction, converging towards the north-east, where the river

THE FRESH-WATER LOCHS OF SCOTLAND.

335

Beauly is formed by the junction of the river Farrar with the river
Glass. The river Glass is formed by the junction of the Amhuinn
Deabhaidh (bearing the outflow from Loch na Beinne Baine) with the
river Affric, while the river Cannich is a tributary of the river Glass.
The river-systems within the Beauly basin, and the relative positions
of the different lochs, are shown on the accompanying index-map
(Fig. 50). The area of the entire basin, as measured with the plani-
meter on the 1-inch Ordnance Survey maps, is about 343 square miles,
of which about 215 square miles (or 63 per cent.) drain into these

J oartfiohme-w

English Miles

I * 3 4 S

FIG. 50. INDEX MAP OF THE BEAULY BASIN.

thirteen lochs, as will be seen from the summary table on p. 350.
An inspection of the summary table shows, further, that all the
lochs exceed half a mile in length, while eight of them exceed a
mile in length; the two largest lochs (Mullardoch and Monar) exceed
4 miles in length, and have each an area exceeding a square mile.
Seven of the lochs exceed 100 feet in depth, and two of them exceed
200 feet, the deepest one being Loch Monar, with a maximum depth
of 260 feet; this loch is also the one containing the largest volume
of water. The boundary-line between the counties of Inverness and
Ross runs up the centre of Loch Monar for the greater part of its
length, and it crosses Loch Mullardoch in its central portion, so that

336 BATHYMETRICAL SURVEY OF

these two lochs lie partly in Ross-shire and partly in Inverness-shire :
four of the others (Lochs Lungard, Calavie, an Tachdaidh, and an Gead)
are situated in Ross-shire, and the remaining seven in Inverness-shire.
The scenery of the district around the lochs is very fine, and the trout
fishing in most of the lochs very good ; some of them contain pike also.

Loch Affric (see Plate LXX VIII.). —Loch Affric (or Affaric) lies
about 26 miles to the south-west of Beauly, which is the nearest railway
station, and about 11 miles from Glen Affric Hotel at Cannich, the
nearest house of entertainment. The loch trends in a west-south-west
and east-north-easterly direction, and is nearly 3J miles in length.
It is broadest towards the western end, where the maximum breadth
is nearly half a mile, narrowing gradually, though irregularly, on
proceeding towards the eastern end, the mean breadth of the entire
loch being a quarter of a mile. The superficial area is about 526 acres,
or over four-fifths of a square mile, and the area drained by the
loch is nearly 47 square miles. The maximum depth of 221 feet was
observed near the centre of the loch. The volume of water is estimated
at 2146 millions of cubic feet, and the mean depth at nearly 94 feet.
The loch was surveyed on October 6 and 7, 1903, when the elevation
of the lake-surface above the sea was determined, by levelling from
bench-mark, as being 747 '0 feet ; when levelled by the officers of the
Ordnance Survey on July 3, 1867, the elevation was found to be
744*1 feet above sea-level, or 3 feet lower than in 1903.

Loch Affric is quite simple in conformation, the deeper water
occupying a central position, from which the bottom slopes upward to
the shores on all sides. The 50-feet contour coincides approximately
with the outline of the loch, enclosing a basin nearly 2J miles in length,
approaching comparatively close to the west end, but distant more than
a quarter of a mile from the east end. Separated from this main 50-
feet basin by shallower water is an isolated sounding of 54 feet, near
the east end, where the main loch is joined by the little subsidiary basin
called Loch Pollan Fearna, in which a maximum depth of 30 feet was
observed. The 100-feet basin is 2J miles in length, and the 150-feet
basin nearly H miles in length, approaching in each case nearer to the
west end than to the east end. The 200-feet basin is about three-quarters
of a mile in length, and is approximately equidistant from both ends of
the loch, but the deepest sounding in 221 feet was taken towards the
west end of the basin, and therefore nearer to the western end of the
loch. A section along the centre of the loch from end to end is shown
in the longitudinal section A-B on the map, and a section across the
loch in the position of the deepest sounding is shown in cross-section
C-D. This last section shows a very slight irregularity in the deepest
part of the loch, where a sounding in 209 feet was taken between a
sounding in 211 feet on the one hand, and the greatest depth of the

THE FRESH- WATER LOCHS OF SCOTLAND. 337

loch (221 feet) on the other. Another line of soundings, about three-
quarters of a mile further east, shows a shoaling in deep water, where
a depth of 122 feet was recorded between a depth of 130 feet on one
side and 159 feet on the other. With these exceptions, the various
lines of soundings show a regular bottom, with a steep offshore slope
in some places along both the northern and southern shores. Thus,
proceeding along the northern shore from the east end of the loch, the
first line of soundings gave a depth of 40 feet at a distance of 20 feet
from shore; the fourth line of soundings gave a similar depth at a
similar distance ; the fifth line gave a depth of 28 feet at 10 feet from
shore; the ninth line gave 47 feet at 30 feet; the next line gave 21
feet at a distance of 20 feet ; the next line 84 feet at 60 feet distance ;
the next 35 feet at 25 feet distance; and the next line 36 feet at 30
feet distance. In like manner, proceeding along the southern shore from
the east end, the sixth line of soundings gave a depth of 76 feet at a
distance of 50 feet from shore; the next line gave 31 feet at 20 feet
distance; the next line 47 feet at 15 feet distance; the next line 33
feet at 20 feet distance ; and the next line 34 feet at 30 feet distance.
All these figures indicate a slope exceeding 1 in 1, and in one case a
slope exceeding 3 in 1. The following table gives the areas between
the consecutive contour-lines at intervals of 50 feet, with the per-
centages to the total area of the loch, the flat-bottomed character of
the basin being indicated by the larger zone on the deeper side of the
100-feet contour than on the shallower side: —

0 to 50 feet 195 acres 37 per cent.

50,, 100 ,, 89 ,, 17

100,, 150 „ 125 „ 24

150,, 200 „ 70 „ 13

Over 200 ,, 47 „ 9

526 , 100 '

Temperature Observations. — A series of temperatures taken at 3 p.m.
on October 6, 1903, in the deepest part of the loch, gave the following
results : —

Surface 49°-2 Fahr.

10 feet 48°-9

25 „ 48°-6

50 „ 48°-0

100 „ 47°'0

150 „ 45°-6

200 „ 44°-8

The extreme range shown by these observations is only 4°-4 from
surface to bottom, the fall of temperature being very gradual.

338 BATHYMETRICAL SURVEY OF

Loch an Laghair (see Plate LXXIX.). — Loch an Laghair lies a
little over a mile to the north-east of Loch Affric, and is practically
continuous with Loch Beinn a' Mheadhoin, for normally the two lochs
stand at the same level, although an easterly gale sets up a strong
current through the narrows at Blar an Ath, in which a depth of
5 feet was observed. The loch trends in a north-east and south-west
direction, and is nearly two-thirds of a mile in length. The maximum
width exceeds a quarter of a mile towards the western end, whence
the loch narrows gradually towards the eastern end. The superficial
area of the loch is about 83 acres, and the area draining directly into it
nearly 6 square miles, but since it receives the overflow from Loch
Affric its total drainage area is about 52J square miles, an area over
400 times greater than that of the loch. The deepest sounding in 100
feet was taken in the central part of the loch, but rather nearer to the
north-east end. The volume of water is estimated at 135 million cubic
feet, and the mean depth at 37J feet. The loch was surveyed on
October 6, 1903; but the elevation of the lake-surface above the sea
could not be determined by levelling, as there was no bench-mark near
the loch. The level was estimated at about 703 feet above sea-level.

Loch an Laghair forms a simple basin, the shallower contours
coinciding approximately with the outline of the loch, but approaching
closer to the northern shore in the eastern half of the loch, where the
offshore slope is steepest. The western end is apparently being silted
up. The 75-feet area is extremely small, for on each side of the
deepest sounding in 100 feet, at a distance represented by twenty
strokes of the oar, the depths were 66 and 64 feet respectively. A
section across the loch at the position of the deepest sounding is shown
in cross-section E-F on the map, and a section along both Loch an
Laghair and Loch Beinn a' Mheadhoin is shown in the longitudinal
section A-B. The area of the lake-floor in Loch an Laghair covered
by less than 50 feet of water is about 63 acres, or 76 per cent, of the
total area of the loch. The temperature of the surface water at
3.30 p.m. on the date of the survey was 48°'0 Fahr.

Loch Beinn a' Mheadhoin (see Plate LXXIX.). — Loch Beinn a'
Mheadhoin (or Beinnavian, or Beneveian) trends generally in a north-
east and south-westerly direction, and is over 2J miles in length. The
loch is fairly uniform in width, the two end portions being somewhat
narrower than the central portion, which has a maximum breadth of
nearly half a mile, the mean breadth of the entire loch exceeding a
quarter of a mile. The superficial area of the loch is about 504 acres,
or over three-quarters of a square mile, and the area of land draining
directly into it is about 15J square miles; but since it receives the
superfluent waters from Lochs Affric and an Laghair, the total drainage
area is about 68 square miles. The maximum depth of 167 feet was

THE FRESH- WATER LOCHS OF SCOTLAND. 339

observed in a central position, but nearer to the eastern than to the
western end of the loch. The volume of water is estimated at 1435
millions of cubic feet, and the mean depth at over 65 feet. The loch
was surveyed on October 6, 1903, but the elevation of the lake-surface
above the sea could not be determined by levelling. The water in the
loch was very high on the date of the survey, the level then being
estimated at about 703 feet above sea-level, but the normal level .is
probably about 700 feet.

Loch Beinn a' Mheadhoin is rather complex in conformation, in-
cluding as it does three deep basins separated by shallower water.
Near the western end of the loch is a small basin having a maximum
depth of 95 feet, and near the eastern end is a larger basin having a
maximum depth of 117 feet, while the largest and deepest basin occupies
the central portion. The two ridges separating these three basins may
be due to the deposition of material brought down by the streams
entering the loch at these places along the northern shore, of which
the westerly stream (Amhainn a' Ghlinne Fhiadhaich) is the more
important; the maximum depth observed on the western ridge was
69 feet, and on the eastern ridge 97 feet. The 25-feet and 50-feet
contours are continuous from end to end of the loch, while the 75-feet
contour is broken at the position of the western ridge, and the 100-feet
contour is broken at the position of the eastern ridge. The eastern
100-feet basin is nearly half a mile in length, and the main 100-feet
basin nearly 1| miles in length; within the last-mentioned basin is a
long, narrow 150-feet basin, based on soundings of 159, 167, and 154
feet, with an isolated sounding in 156 feet a quarter of a mile farther
west. It seems doubtful whether this isolated sounding may not be
connected with the principal basin by deep water, and in that case the
150-feet basin would be nearly a mile in length. The deepest sounding
in 167 feet was recorded about a mile from the eastern end of the loch,
and about H miles from the western end. The cross-section C-D, in
this position, shows a steeper gradient off the northern than off the
southern shore; but the soundings, as a whole, afford no evidence of
any very steep slopes. The deeper part of the loch has quite a flat-
bottomed character, as indicated by the figures in the following table,
giving the areas between the consecutive contour-lines : —

0 to 25 feet 98 acres 19 '5 per cent.

25,, 50 „ 80 „ 15-8

50,, 75 „ 96 „ 19-0

75 „ 100 „ 174 „ 34-5

Over 100 , 56 . 11-2

504 , 100-0

It will be observed that the largest zone is the one between 75 and
100 feet, and that the area of the lake-floor covered by less than 50 feet

340 BATHYMETRICAL SURVEY OF

of water is about 178 acres, as compared with 270 acres covered by
water between 50 and 100 feet in depth, or 35 per cent, as compared
with 53 per cent. In most lakes the arrangement is the reverse of this,
the areas between consecutive contour-lines drawn at equal intervals
usually decreasing with increase of depth. The temperature of the
surface water at the east end on commencing the survey was 50°'0
Fahr., while later in the afternoon, towards the opposite end the
surface temperature was 49°-5 ; but an easterly gale having sprung
up, it was found impossible to take serial temperatures beneath the
surface.

Loch na Beinne Baine (see Plate LXXXIL). — Loch na Beinne
Baine lies in Guisachan forest, about 4 miles to the south-east of Loch
Beinn a' Mheadhoin, and 8 or 9 miles to the west of Invermoriston on
Loch Ness. It is irregular in outline, trends in a north-north-east and
south-south-westerly direction, and is nearly a mile in length, with a
maximum breadth of nearly half a mile. The superficial area is about
154 acres, or a quarter of a square mile, and the area draining into it
about 1J square miles. The maximum depth of 67 feet was observed
about a quarter of a mile from the southern end of the loch, midway
between an island of stones and the eastern shore. The volume of
water is estimated at 190 million cubic feet, and the mean depth at
28 J feet. The loch was surveyed on June 6, 1904, but the elevation of
the lake-surface above the sea could not be determined ; the height of
the water at the sluice was about 2 feet, and at one time the loch
appears to have been considerably higher.

Loch na Beinne Baine forms a simple basin ; the 25-feet contour
coincides approximately with the outline of the loch, but is deflected at
the position of the island of stones off the western shore towards the
southern end, while the 50-feet basin, based on soundings of 67, 64, 54,
and 52 feet, is contained in the southern half of the loch, and is about
a quarter of a mile in length. The soundings indicate in one or two
places slight undulations of the lake-floor, but as a rule the slope of
the bottom is regular and gentle. The area covered by less than 25 feet
of water is about 95 acres, or 62 per cent, of the total area.

Temperature Observations. — A series of temperatures taken in the
deepest part of the loch gave the following results : —

Surface 60° '8 Fahr.

10 feet 60°'0 ,,

20 „ 50°-5 „

40 „ 47°'6 „

60 „ ... 46°'5 „

These observations indicate an extreme range of temperature from
surface to bottom amounting to 14°-3, there being a fall of 9°'5 between

THE FRESH- WATER LOCHS OF SCOTLAND. 341

10 and 20 feet, which is nearly equal to a fall in temperature of one
degree per foot of depth. Reference has elsewhere been made to the
large range and rapid fall of temperature observed in Lochs Monzie-
vaird, Achilty, and Dubh,* and the temperatures here given from
Loch na Beinne Baine afford another instance for comparison.

Loch Lungard (see Plate LXXXIL). — Loch Lungard (or Longart,
or Glasletter) lies at the head of Glen Cannich, about 5 miles to the
north of Loch Affric. It trends east and west, and is 1 J miles in length,
with a maximum breadth towards the west end of one-third of a mile,
whence the loch narrows gradually towards the east. The superficial
area is about 216 acres, or one-third of a square mile, and the area
draining into it is nearly 23 square miles. The maximum depth of
129 feet was observed in a central position, but towards the east end.
The volume of water is estimated at 599 million cubic feet, and the
mean depth at nearly 64 feet. The loch was surveyed on October 7,
1903, when the elevation of the lake-surface above the sea was found,
by levelling from bench-mark, to be 761-3 feet, which is nearly identical
with the level observed by the Ordnance Survey officers on October 14,
1867, viz. 761-2 feet. When surveyed the water was about its normal
level, and in floods might rise about 3 feet.

Loch Lungard is extremely simple in conformation, the bottom
sloping down on all sides towards the deepest part, not the slightest
irregularity being indicated by the soundings, while the contour-lines
coincide approximately with the outline of the loch. This is shown in
both the longitudinal section A-B and the cross-section C-D on the
map. The 50-feet basin is 1J miles, and the 100-feet basin rather under
a mile, in length, and they are comparatively wide, so that the loch is
of a flat-bottomed character, as is shown by the following table, giving
the areas and percentages between the contour-lines : —

0 to 50 feet 87 acres 40 per cent.

50,, 100 „ 81 „ 38

Over 100 „ 48 „ 22

216 „ 100

Temperature Observations. — The following series of temperatures,
taken at 2 p.m. on the date of the survey in the deepest part of the
loch, indicates a range of only l°-2 Fahr. throughout the body of
water : — •

Surface 49° '2 Fahr.

25 feet 49°-0 „

50 „ 48°-8 „

125 „ 48°-0 „

* See p. 276.

342 BATHYMETRICAL SURVF.Y OF

Loch Mullardoch (see Plate LXXX.).— Loch Mullardoch (or
Mulardich, or Moyley) lies less than 2 miles to the east of Loch
Lungard, and is practically continuous with Loch Sealbhag, there
being a small expansion of the river between them called Loch Ath
a' Bhan, which was not sounded. Loch Mullardoch trends generally
in an east and westerly direction, and is somewhat irregular in outline,
with a slight bend in the central portion. It exceeds 4 miles in length,
and is pretty uniform in width, the maximum breadth being less than
half a mile, and the mean breadth over a quarter of a mile. Its waters
cover an area of about 756 acres, or considerably more than a square
mile, and the area draining directly into it is about 27 J square miles ;
but since it receives the outflow from Loch Lungard its total drainage
area exceeds 50 square miles. The maximum depth of 197 feet was
observed in the eastern portion of the loch, about a mile and a half
from the east end. The volume of water is estimated at 2553 millions
of cubic feet, and the mean depth at 77J feet. The loch was surveyed
on October 7, 1903, but the elevation above the sea was not determined ;
when levelled by the Ordnance Survey officers on November 29, 1866,
the elevation of the lake-surface was found to be 704*9 feet above sea-
level. On the date of the survey the water was about a foot above the
normal level, and two days previously it had been 3 feet higher.

Loch Mullardoch is divided into two deep basins by a shoaling of
the water in its central portion, where there is a constriction and bend
in the outline, the maximum depth in the western basin being 150 feet,
and in the eastern basin 197 feet, the depth on the shoaling being 80
feet. A section across the deepest part of the western basin is shown in
cross-section C-D, and one across the deepest part of the eastern basin
in cross-section E-F, on the map, and a section along the centre of the
loch from end to end is shown in the longitudinal section A-B at the
foot of the map. This last-mentioned section brings out the central
shoaling referred to, which is apparently traceable to the influence of
the streams entering on both sides of the loch at this place, and
principally of the Allt Taige, at the mouth of which, on the northern
shore, is a considerable delta. The 50-feet contour is continuous, and
encloses a basin nearly 4 miles in length. The western 100-feet basin
exceeds half a mile in length, separated by an interval of over half a
mile from the eastern 100-feet basin, which is one and a half miles in
length, and includes a 1 50-feet basin over a mile in length. All the
cross-lines of soundings show a regular bottom, the water deepening
gradually from the shore towards the centre, with a steep offshore slope
in some places, as, for instance, along the southern shore off Creag
Dubh, where a sounding in 24 feet was taken about 20 feet from shore,
and off Creag a' Bhaca, at the deepest part of the loch, where a sounding
in 94 feet was taken about 100 feet from shore. The following table
gives the approximate areas between the consecutive contour-lines at

THE FRESH- WATER LOCHS OF SCOTLAND. 343

intervals of 50 feet, and the percentages to the total area of the loch,
and indicates the flat-bottomed character of the basin, the comparatively
large area of the lake-floor covered by more than 150 feet of water
being noteworthy : —

0 to 50 feet 298 acres 39 per cent.

50,, 100 „ 228 „ 30

100,, 150 ,, 121 „ 16

Over 150 , 109 . 15

756 „ 100

Temperature Observations. — The following series of temperatures,
taken at 4.30 p.m. on the date of the survey in the western basin,
shows that the water was nearly uniform in temperature, the extreme
range from surface to bottom being only 1° Fahr., the readings down
to a depth of 50 feet being identical: —

Surface 50° '0 Fahr.

lOfeet 50°-0 ,,

25 „ 50°-0 „

50 „ 50°'0 „

100 „ 49°-5 „

150 „ : 49°-0 „

Loch Sealbhag (see Plate LXXX.). — Loch Sealbhag lies to the east
of, and is, as already stated, practically a continuation of Loch Mullar-
doch. It trends in a north-east and south-westerly direction, and is
two-thirds of a mile in length, with a maximum breadth towards the
west end of nearly a quarter of a mile, whence it narrows gradually
towards the north-east. Its waters cover an area of about 68 acres, and
it drains directly an area of 3J square miles, but since it receives the
outflow from Lochs Lungard and Mullardoch, its total drainage area
is nearly 54 square miles — an area nearly 500 times greater than that
of the loch. The maximum depth of 56 feet was observed in the
widest part of the loch towards the western end, and comparatively
near the southern shore. The volume of water is estimated at 61
million cubic feet, and the mean depth at over 20| feet. The loch
was surveyed on October 5, 1903, but the elevation above the sea could
not be determined.

The wide western portion of Loch Sealbhag includes a deep basin
exceeding 30 feet in depth, which approaches comparatively close
to the western end, and is over a quarter of a mile in length. To
the north-east of this basin the bottom rises, and falls again on
approaching the outfall to a depth of 31 feet, the depth on the rise
being 16 feet. The area of the lake-floor covered by less than 20 feet
of water is about 39 acres, or 57 per cent, of the total area. The
temperature of the surface water on the date of the survey was
50°-5 Fahr.

344 BATHYMETRICAL SURVEY OF

Loch Calavie (see Plate LXXXII.).— Loch Calavie (or Calvie) lies
about 6 miles to the north-west of Loch Lungard, and only 7 miles from
the head of Loch Carron on the west coast of Scotland, at a high
elevation among the mountains, the lower slopes of which are covered
with peat. The loch trends in a north-west and south-easterly direction,
and is considerably over a mile in length, with a maximum width
towards the western end exceeding one-third of a mile, whence the
breadth gradually decreases on approaching the eastern end. The
superficial area is about 167 acres, or a quarter of a square mile, and
the area draining into it nearly 2| square miles. The maximum depth
of 84 feet was observed in a central position, but rather nearer the
western than the eastern end. The volume of water is estimated
at 276 million cubic feet, and the mean depth at 38 feet. The loch
was surveyed on October 19, 1904, when the elevation was found by
levelling from bench-mark to be 1128-35 feet above the sea — a little
lower than the elevation as determined by the Ordnance Survey officers
on August 14, 1866, viz. 1128-5 feet above sea-level.

Loch Calavie is perfectly simple in conformation, the contour-lines
coinciding approximately with the shore-line, though in each case they
approach nearer to the western than to the eastern end of the loch, so
that the average slope is steeper towards the head of the loch. This
is shown in the longitudinal section A-B on the map. The 25 -feet
basin is nearly a mile, and the 50-feet basin three-quarters of a mile,
in length. The soundings give no indication of any steep offshore
slopes, and the average slope between the 25-feet and 50-feet contours
is less steep than in shallower water, as indicated in the following
table by the larger area beyond the 25-feet line: — •

0 to 25 feet 55 acres 33 per cent.

25 „ 50 „ 62 „ 37 „

50,, 75 „ 39 ,, 24

Over 75 „ 11 ,, 6

167 , 100

Temperature Observations. — The following series of temperatures
taken in the deepest part of the loch shows that on the date of the
survey the whole body of water was practically uniform in temperature,
the extreme range being less than 1° Fahr. : —

Surface 47°'OFahr..

40 feet 46°-3 „

75 „ 46°-2 ,,

Loch an Tachdaidh (see Plate LXXXII.). — Loch an Tachdaidh
lies about 2 miles to the east of Loch Calavie, and is almost continuous
with Loch an Gead, the stream between them being a very short one,

THE FRESH- WATER LOCHS OF SCOTLAND. 345

and the difference in level only 1^ feet. The term Gedd Lochs is
applied to the connected series, consisting of Loch an Gead, Loch an
Tachdaidh, and the neighbouring little Loch an Gobhlach, which was
not sounded. Loch an Tachdaidh is irregular in outline, trends in a
north-east and south-westerly direction, and is nearly two-thirds of a
mile in length, with a maximum breadth exceeding one-third of a mile.
Its waters cover an area of about 92 acres, and it drains directly an
area exceeding 4 square miles, but since it receives the overflow from
Loch Calavie, its total drainage area is over 6J square miles. The
maximum depth of 62 feet was observed in the centre of the north-
eastern portion of the loch, near a heap of stones showing above the
surface of the water. The volume of water is estimated at 72 million
cubic feet, and the mean depth at 18 feet. The loch was surveyed on
October 21, 1904; the elevation could not be determined by levelling,
but was estimated at about 831 '5 feet above the sea.

Loch an Tachdaidh is irregular in conformation as well as in out-
line, and, besides the island of stones already mentioned, includes four
small unnamed islands, the largest of which occupies a central position ;
the south-western portion is shallow and filled with weeds. The
contour-lines are sinuous in character, the deepest part lying between
the largest island and the heap of stones, where three soundings ex-
ceeding 50 feet in depth were taken. To the south of the largest
island, and towards the eastern shore, a sounding in 25 feet was
recorded, surrounded by shallower water. The area of the lake-floor
covered by less than 25 feet of water is about 74 acres, or 8.1 per cent,
of the total area.

Temperature Observations. — The following series of temperatures
taken in the position of the deepest sounding shows a range of only
1°'2 Fahr. throughout the body of water, the deeper layers being
uniform in temperature : —

Surface 46° -2 Fahr.

30 feet 45°-0 „

60 „ 45°-0 „

An Gead Loch (see Plate LXXXII.).— An Gead Loch lies to the
north-east of Loch an Tachdaidh, and trends in a similar direction, but
is more regular in outline and more uniform in width. An Gead Loch
is nearly 1J miles in length, with a maximum width towards the south-
west end of a quarter of a mile. The superficial area is about 110 acres,
and the area draining directly into it is about 2J square miles, but
since it receives the outflow from Lochs Calavie and an Tachdaidh,
the total drainage area exceeds 9 square miles. The maximum depth of
30 feet was observed towards the north-eastern end of the loch. The
volume of water is estimated at 54 million cubic feet, and the mean
depth at 11 J feet. The loch was surveyed on October 21, 1904, and the

346 BATHYMETRICAL SURVEY OF

elevation was estimated at about 830 feet above sea-level. The bottom
of an Gead Loch is irregular and stony, so much so that in the deeper
part no mud could be got, while the shallow western portion is covered
with sand. Though irregular, the basin has a flat-bottomed character,
for the majority of the soundings were taken in depths exceeding 10
feet, and only three soundings in depths exceeding 20 feet. The area of
the lake-floor covered by more than 10 feet of water is about 62 acres,
or 56 per cent, of the total area. The temperature of the water was
nearly uniform on the date of the survey, a reading at the surface
giving 46°-7 Fahr., and a reading at 25 feet 46°-0.

Loch Monar (see Plate LXXXI.). — Loch Monar lies at the head
of Glen Strath Farrar, little more than a mile to the north-east of
an Gead Loch, and is one of the most important lochs in the Beauly
basin. In length and in superficial area it is slightly inferior to Loch
Mullardoch, but it is the deepest of the series, and contains the largest
volume of water. The general trend of Loch Monar is east and west,
but with a slight sinuosity in the outline, the length exceeding 4 miles.
The width varies considerably, the maximum breadth of nearly half a
mile occurring near the west end, the mean breadth of the entire loch
exceeding a quarter of a mile. The waters of the loch cover an area
of about 750 acres, or over one square mile, and the area draining
directly into it is about 41 square miles, but since it receives the
overflow from Lochs Calavie, an Tachdaidh, and an Gead, the total
drainage area is about 50 square miles. The maximum depth of 260
feet was observed much nearer the eastern than the western end.
The volume of water is estimated at 3213 millions of cubic feet, and
the mean depth at 98J feet. The loch was surveyed on October 10,
1903, when the elevation of the lake-surface above the sea was found
to be 663-9 feet ; when levelled by the officers of the Ordnance Survey
on June 20, 1866, the elevation was 662-8 feet above sea-level. At the
time of the survey the water was about its normal level, and might
rise to the extent of several feet.

Loch Monar is quite simple in conformation, all the contour-lines
enclosing continuous areas, and the cross-lines of soundings indicating
a regularly sloping bottom from the shores out towards the centre of
the loch. The longitudinal section, A-B on the map, along the centre
of the loch from end to end shows slight undulations of the lake-floor,
the shallowings coinciding with constrictions in the outline. The
contour-lines all approach nearer to the eastern than to the western
end of the loch, showing a steeper slope in an easterly direction from
the deepest sounding, which was taken less than a mile from the east
end, or one-fourth of the distance from one end to the other. The off-
shore slope is in places very steep, especially along the southern shore
at the deepest part of the loch, where near the centre of the loch a

THE FRESH-WATER LOCHS OF SCOTLAND. 347

sounding in 104 feet was taken about 120 feet from shore; a little
farther east another sounding in 50 feet was taken about 50 feet from
shore; still farther east a sounding in 148 feet was taken about 120
feet from shore ; and still farther east a sounding in 87 feet about
60 feet from shore. The last-mentioned sounding, which gives a slope
of 29 in 20, was taken on the cross-line immediately to the east
of the deepest sounding, and the steepest gradient observed off the
northern shore was at the opposite end of the same line, where a
sounding in 54 feet was taken at about 60 feet from shore. The cross-
section C-D on the map is taken at the position of the deepest sounding,
and shows a gentle offshore slope, succeeded by a steeper slope on
proceeding into deep water, the deeper part of the loch being of a
flat-bottomed character. The area enclosed by the 50-feet contour is
nearly 3 J miles in length, being distant from the west end nearly three-
quarters of a mile, and extending into the narrow part at the east end
off Creag Ghrada ; in the expansion of the out-flowing river, opposite
Creag Dubh, a depth of 64 feet was observed. The 100-feet basin
is 3 miles, the 150-feet basin 2J miles, and the 200-feet basin over one
mile, in length. The approximate areas between the consecutive
contour-lines drawn in at equal intervals, and the percentages to the
total area of the loch, are given in the following table, from which
it will be noticed that the area of the zone between 150 and 200 feet is
larger than that of the two preceding shallower zones : —

Oto 50 feet 293 acres 39 per cent.

50,, 100 „ 134 „ 18

100,, 150 „ 99 „ 13

150,, 200 „ 138 „ 18

Over 200 „ 86 ,, 12 „

750 „ 100 „

Temperature Observations. — The following series of temperatures,
taken in the deepest part of the loch at 4 p.m. on the date of the survey,
shows that the whole body of water varied little in temperature, being,
in fact, uniform in temperature down to 100 feet, the extreme range
amounting to only l°-2 Fahr.

Surface 49°'5Fahr.

10 feet 49°-5 „

25 „ 49°-5 „

50 49°-5 ,,

100 „ 49°'4 „

150 , 49°'0 „

170 „ 48°-5 ,,

200 „ 48°-3 „

Lurh a Mhuilinn (see Plate LXXXII.).— Loch a' Mhuilinn (or
Moilie) is a small irregular loch lying about 5 miles to the east of Loch

348 BATHYMETRICAL SURVEY OF

Monar. A terrace of gravel surrounds the loch, except on the northern
shore, where the hill an Carnach rises steeply from the lake-shore.
There is a large island named Eilean a' Mhuilinn near the east end, and
two smaller islands at the mouth of the inflowing river at the west end.
The loch trends in an east-north-east and west-south-westerly direction,
and is nearly a mile in length, with a maximum breadth in the centre
exceeding one-third of a mile, whence it narrows towards the two ends.
The superficial area is about 100 acres, and the area of land draining
directly into it is about 37f square miles, but since it receives the
overflow from Lochs Monar, an Gead, an Tachdaidh, and Calavie, its
total drainage area is nearly 88 square miles — an area 550 times greater
than that of the loch. The maximum depth of 94 feet was observed in
the wide part of the loch towards the northern shore. The volume of
water is estimated at 150 million cubic feet, and the mean depth at
over 34 feet. The loch was surveyed on October 12, 1903, when the
elevation was determined, by levelling from bench-mark, as being
417-65 feet above the sea; when visited by the Ordnance Survey officers
on June 1, 1866, the elevation was found to be 417'5 feet above sea-
level. A drift-mark was observed 5 feet above the surface of the
water on the date of the survey, when the level was about its normal.

Loch a' Mhuilinn consists of a deep central basin, with two small
subsidiary shallow basins at the two ends, as shown in the longitudinal
section on the map. Towards the west end, immediately to the north
of the island at the mouth of the inflowing river, a depth of 25 feet was
recorded, separated from the main basin by a rise of the bottom, on
which a maximum depth of 12 feet was observed. Towards the east
end, between Eilean a' Mhuilinn and the mouth of the outflowing river,
a depth of 24 feet was recorded, separated from the main basin by a
depth of 3 feet in the narrows between the island and the northern
shore. In the main deep basin the contour-lines are continuous and
the bottom regular, seven soundings in depths exceeding 80 feet having
been recorded to the west and south-west of Eilean a' Mhuilinn, two of
them in depths exceeding 90 feet. The area of the lake-floor covered
by less than 50 feet of water is about 72 acres.

Temperature Observations. — The following series of temperatures
taken in the deepest part of the loch shows that the body of water was
nearly uniform in temperature on the date of the survey, the extreme
range observed being less than 1° Fahr. : —

Surface 47°'2 Fahr.

10 feet 47°'0 „

25 „ 46°-8 „

50 „ 46°'6 „

90 „ 46°4 ,,

Loch Butiacharan (see Plate LXXXII.). — Loch Bunacharan (or

THE FRESH- WATER LOCHS OF SCOTLAND. 349

Banchron) lies less than a mile to the east of Loch a' Mhuilinn and
about 6 miles east of Loch Monar, and is the final one of the series of
lochs in Glen Strath Farrar. The shores are mostly of gravelly debris,
forming terraces about 20 feet high, which are best seen along the south
shore; the surrounding hills are high and rugged, and well wooded.
The loch trends east-north-east and west-south-west, and is 1J miles in
length, with a maximum width of nearly one-third of a mile, the
superficial area being about 157 acres, or a quarter of a square mile.
The area draining directly into Loch Bunacharan is only about 4 square
miles, but it receives the overflow from Lochs Calavie, an Tachdaidh,
an Gead, Monar, and a' Mhuilinn, and its total drainage area is there-
fore a very large one — about- 92 square miles. The maximum depth of
113 feet was observed towards the east end of the loch — less than
half a mile from the east end and more than three-quarters of a mile
from the west end. The volume of water is estimated at about 343
million cubic feet, and the mean depth at over 50 feet. The loch was
surveyed on October 12, 1903, when the elevation of the lake-surface
above the sea was found, by levelling from bench-mark, to be 366*15
feet; when levelled by the officers of the Ordnance Survey on June 9,
1866, the elevation was 366-5 feet above sea-level. On the date of the
survey the water was about its normal level, and a recent drift-mark
was observed 9 feet above the surface of the water, while an older drift-
mark was 11 feet above the water-surface.

Loch Bunacharan is irregular in conformation, the lake-floor in the
deeper part of the loch rising and falling in a series of undulations.
The 25-feet and 50-feet contours are continuous from end to end of the
loch, and coincide approximately with the shore-line. The 75-feet
contour, however, encloses three distinct basins separated from each
other by shallower water, viz. — (1) a very small basin based on a
sounding in 83 feet about 300 yards from the western end ; (2) a larger
basin a quarter of a mile in length, and trending almost north and
south, i.e., transversely across the loch, based 011 soundings in 78, 82,
and 88 feet, situated about one-third of a mile from the western end ;
and (3) the largest and deepest basin, one-third of a mile in length,
approaching to within a quarter of a mile from the eastern end, and
enclosing a small basin exceeding 100 feet in depth, based on soundings
in 105, 111, and 113 feet. Between the second and third basins above
noted there is a rise of the lake-floor near the middle of the loch,
covered by 43 feet of water, surrounded on all sides by deeper water.
These inequalities are indicated to some extent in the longitudinal
section A-B on the map, taken along the axis of maximum depth, but
most of the cross-lines of soundings show a regular bottom, as shown in
cross-section C-D, taken at the position of the deepest sounding. The
slope of the bottom seems to be gentle on the whole, the steepest
gradient observed being off the northern shore towards the west end,

350

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BATHYMETRICAL SURVEY OF

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THE FRESH- WATER LOCHS OF SCOTLAND. 351

where a sounding in 48 feet was taken about 50 feet from shore. The
area of the lake-floor covered by less than 50 feet of water is about
80 acres, or 51 per cent, of the total area.

Temperature Observations. — The following series of temperatures,
taken in the deepest part of the loch, show that the whole body of
water was practically uniform in temperature : —

Surface 48°-2Fahr.

25 feet 48°-2 „

50 „ 48°-0 „

75 , 48°-0 ,,

90 „ 4800 „

110 „ 47°'9 „

The particulars regarding the lochs in the Beauly basin are collected
together in the table on p. 350 for convenience of reference and com-
parison. From this table it will be seen that in the thirteen lochs
under consideration, which cover an area of 5J square miles, about 850
soundings were taken, or an average of 146 soundings per square
mile of surface. The aggregate volume of water contained in the lochs
is estimated at 11,230 millions of cubic feet, and the area draining into
them is over 215 square miles, or 37 times the area of the lochs.

GEOLOGICAL NOTES ON THE LOCHS WITHIN THE BASIN OF THE FARRAR.
By B. N. PEACH, LL.D., F.R.S., and J. HORNE, LL.D., F.R.S.

The mapping of the western part of the Beauly basin by the
Geological Survey has only been carried southwards to the watershed
between Glen Strath Farrar and Glen Cannich, and hence the following
notes are confined to the lakes lying within the basin of the Farrar.
This area is entirely occupied by the metamorphic rocks of the High-
lands, which have been arranged in two divisions — (1) an older series,
which has been correlated with the Lewisian or Archaean gneiss of the
West Highlands ; and (2) a group of crystalline schists, termed the
Moine series by the Geological Survey, which are regarded as altered
sediments, and are supposed to rest unconformably on the older
Lewisian gneiss.

The members of the older series comprise hornblendic and biotite
gneisses and ultrabasic masses, together with crystalline limestone,
graphite schists and eclogites, which resemble the rocks of Lewisian age
in the neighbourhood of Glenelg. The Moine series includes two
prominent subdivisions — (1) flaggy and massive quartz-biotite
granulites; and (2) muscovite-biotite schists, the latter probably
representing an argillaceous phase of sedimentation. In the basin of

352 BATHYMETRICAL SURVEY OF

the Farrar the general strike of the crystalline schists, with the
exception of local variations, is north-north-east and south-south-
west, or north-east and south-west — that is to say, obliquely across
the course of the main valley.

The basin of the Farrar is traversed by a powerful dislocation, which
.passes from the Conon valley in a south-west direction by Gleann
Chorainn and the head of the river Orrin, thence across Loch Monar
to the south-west shoulder of Riabhachan. It forms a well-marked
feature, and is accompanied by much brecciation and staining of the
rocks, as may be seen along its course to the north-east of Loch Monar.
At certain localities, parallel or branching faults, presumably con-
nected with the main dislocation, are met with, which modify to some
extent the surface features.

During the period of confluent glaciers, the ice radiating from the
mass of high ground south of Loch Monar, embracing Sgurr na Lapaich
(3773 feet) and an Riabhachan (3696 feet), and from the heights
between that lake and Gleann Fhiodhaig to the north, flowed eastwards
down Glen Strath Farrar, and streamed northwards through some of
the passes towards the Orrin and Glen Fhiodhaig, and westwards in
the direction of the valley of the Ling. At a later stage it escaped
only by Strath Farrar. The diverging movement through the various
passes is indicated partly by ice-markings and partly by the disposition
of the moraines.

Loch Monar is a true rock basin carved mainly out of the crystalline
schists of the Moine series, modified by the movements accompanying
the Strath Conon fault and its branches, to which reference has already
been made. The lip of the basin is now about half a mile below the
present outlet of the lake, the intervening area being silted up by the
alluvium brought down by Allt Coire na Faochaige — a tributary which
joins the main stream opposite Monar Lodge. The rocks forming the
barrier of the lake are well seen in the gorge of the Garbh-uisge, where
they consist of massive siliceous Moine schists, intensely plicated along
vertical axes trending north-east and south-west.

In the narrow part of the lake immediately above Monar Lodge
there is a small subsidiary basin, which may be accounted for by
inequalities in the hardness of the rocks, and by the irregular dis-
tribution of the drift on the west side of the loch. The deep part of
the main basin coincides with the belt of crushed strata accompanying
the Strath Conon fault that crosses the lake near Lub-an-Inbhir and
the parallel dislocation above Creag na h-Iolaire. A third fault,
trending east and west, enters the loch at the mouth of the Allt nan
Uan, which has produced considerable brecciation of the rocks.

The shallow bar near the head of the loch is due to a spit of sand,
brought down partly by the Allt Riabhachan and partly by the stream
at Pait, which has been distributed by the action of the waves.

THE FRESH- WATER LOCHS OF SCOTLAND. 353

The long stretch of alluvium along the Amhainn-an t-Sratha Mhoir
indicates that the lake has been silted up for about a mile above its
present western limit.

Loch an Tachdaidh and an Gead Loch. — These lochs lie in the
bottom of the valley drained by the Garbh-uisge at Pait, which flows
into Loch Monar, and are entirely surrounded by drift deposits of the
later glaciation. All the small projections into these lakes are due to
moraine heaps, arranged in such a way as to suggest that they are
probably the terminal moraines of a lobe of ice that moved westwards
towards the basin of the river Ling.

Loch Calavie lies in one of the passes through which the ice escaped
westwards from the Moiiar area during the period of confluent glaciers.
Though immediately surrounded by moraines and peat, it is evidently
in part a rock basin, as the rocky barrier formed of muscovite-biotite
gneiss appears in the stream not far below the outlet of the lake. The
deepest sounding is 84 feet.

Loch Bunacharan- and Loch a' Mhuilinn. — These lakes are situated
in the valley of the Farrar about midway between Loch Monar and
Struy. Their long axes seem to coincide generally with the strike of
the crystalline schists. In the case of the former lake, its height above
sea-level is 366 feet, its greatest depth 113 feet, and the position of the
rocky barrier exposed in the stream about one-third of a mile below
the outlet is about 360 feet. The surface level of Loch a' Mhuilinn is
417 feet, and the deepest sounding is 94 feet, and as it discharges over
solid rock, it is evidently a small rock basin. There is a high terrace
round Loch a' Mhuilinn and 011 the south side of Loch Bunacharan at
a level of 440 feet.

NOTES ON THE BIOLOGY OF THE LOCHS OF THE BEAULY BASIN.
By JAMES MURRAY.

The lochs of Beauly valley were surveyed in late autumn, during
very severe weather, unfavourable for the study of biology. The lochs
in Glen Affric were visited in a time of heavy floods, which raised the
lochs several feet while we were working at them. Though the tow-nets
were used, there was almost nothing got in them. The lochs appeared
to be flushed and washed out by the spate, or else the animals had gone
down to quieter water.

Throughout the rest of the basin there was great uniformity, the
ordinary universal limnetic Crustacea and Rotifers alone being present,
with little call for remark. There was an entire absence of all the
northern species of Diaptomus, and, although Desmids were fairly
abundant in most of the lochs, there were none of the western species.

z

354 BATHYMETRICAL SURVEY OF

The few species which only occurred in some of the lochs are noted
below. These are also generally distributed in summer, their scarcity
in these lochs being due to the late season at which they were visited.

Daphnia. — In all the lochs where Daphnia occurred, it was as the
variety galeata, a large form with the head angled.

Holopedium gibberum. — Only in Lochs Calavie and an Tachdaidh.

Leptodora kindtii. — Only in Loch Monar.

Polyphemus pediculus. — An Gead Loch.

Cy clops strenuus. — Present in most of the lochs. The Cyclops in
Loch Calavie were red-spotted.

Diaphanosoma brachyurum. — Found in four lochs — an Tachdaidh,
Bunacharan, Mullardoch, and Lungard.

Floscularia pelagica. — Loch Monar.

Conochilus. — Both species, C . unicornis (the common lake species)
and C '. volvox, were present in Loch Monar.

Sponge. — A fresh-water sponge, species not determined, came up
attached to the sounding-rod, from depths of 6 or 8 feet, in Loch a'
Mhuilinn. The pieces were long, finger-shaped.

THE FRESH- WATKR LOCHS OF SCOTLAND.

355

LOCHS OF THE LOCHY BASIN.

THE Lochy basin is a large and important one, having on its boundary-
line and within it some of the highest peaks in Scotland, including the

English Miles

o * 10 is 20

FIG. 51. INDEX MAP OF THE LOCHY DISTRICT.

highest — Ben Nevis. It stretches from Sgor nan Coireachan on the west
to Meall Cruaidh and Creag Ruadh on the east, a distance of over 40
miles, and from Glas Bheinn and Leim Uilleim on the south to Carn
Dearg and Carn Leac on the north, a distance of over 20 miles, the
total area of the basin exceeding 400 square miles. Within this basin
ten lochs were sounded by the Lake Survey staff, viz., Lochs Lochy,
Arkaig, Pattack, na h-Earba (east and west), Laggan, Ossiau, Ghuil-
binn, Treig, and an Dubh Lochan. Five of the lochs exceed 3 miles in
length, and four exceed 5 miles in length, while one of them (Loch

356 BATHYMETRICAL SURVEY OF

Arkaig) is 12 miles in length; five of them exceed 100 feet in depth,
and three exceed 300 feet in depth, while one of them (Loch Lochy)
exceeds 500 feet in depth. It has been found convenient to include
also two small lochs which drain directly' into Loch Linnhe, viz.,
Lochan Limn da-Bhra on the east and Loch nan Gabhar on the west.
Loch nan Gabhar is in Argyllshire, while all the remaining lochs are
situated in Inverness-shire. The relative positions of the lochs and
rivers within the area under discussion are shown in the little index
map (Fig. 51), from which it will be seen that Loch Arkaig drains into
Loch Lochy by the short river Arkaig, while the other lochs within
the basin drain into the river Spean, which joins the river Lochy
shortly after its exit from Loch Lochy, the junction of the two rivers
being marked by the pretty falls of Mucomir.

The Lochy basin, only a small portion of which has been mapped
by the Geological Survey, lies wholly within the region of the crystal-
line schists of the Central Highlands. It is intersected by the powerful
north-east and south-west fault that traverses the Great Glen from
Inverness to the shores of Loch Linnhe. In the area west of this
dislocation the rocks, so far as known, consist of quartz-biotite granu-
lites and muscovite-biotite schists, which are believed to represent
altered sediments. These are traversed by acid and basic intrusions
and numerous veins of granite and pegmatite.

East of the Great Glen several of the metamorphic groups of the
Eastern Highlands are represented, including the Perthshire quartzite,
black schist, limestone, Ardrishaig phyllites, and the associated quart-
zite, the beds striking generally in a north-east and south-west direction.
The schists are pierced by various masses of igneous rock, of which
the most important is the large intrusion of granite forming the lower
part of Ben Nevis. It is capped by andesitic lavas, breccias, and tuffs,
presumably of Lower Old Red Sandstone age.

Loch Lochy (see Plate LXXXIII.). — Loch Lochy is the southern-
most of the chain of lochs occupying the Great Glen which were
utilized in forming the Caledonian Canal. Its southern end is about
8 miles north of Fort William. It is a straight loch, running nearly
north-east to. south-west. In form Loch Lochy is a narrow triangle,
with the apex at the north end, gradually widening southward to near
Bunarkaig, where the greatest breadth is found, after which it rapidly
narrows for the remaining 2 miles to the outflow at Gairlochy. A good
road runs along the eastern shore, a rough cart-road on the western
side, and several stations of the Invergarry and Fort- Augustus railway
now give easy access to the loch on the east side. The surroundings are
wild, gloomy, and solitary (see Fig. 52). No village is found on its
shores, an occasional house being passed on the east side, while the
west side is uninhabited, save for one or two distant cots.

THE I RKSH-WATER LOCHS OF SCOTLAND. 357

The hills on the west rise with a uniform very steep slope to a
height of more than 3000 feet (Sron a Choire Ghairbh), broken only
by the deep gashes torn by the torrents in the glacial debris, which here
extends far up the mountains. On the east the slope is about the same,
but the hills less high, the ridge (almost wholly covered with debris)
which separates Loch Lochy from Glen Gloy reaching to 2000 feet.

The only important streams feeding the loch are the river Arkaig,
bearing the superfluent waters from Loch Arkaig, entering near the
lower end, and a large burn coming down Glen Gloy, the rest of

FIG. 52. LOCH LOCHY, FROM THE SOUTHERN END.

(Photograph by Mr. James Chumley.)

the feeders being mere mountain torrents. A very small portion of
the overflow of Loch Oich enters Loch Lochy by the Caledonian Canal.

The length of the loch is a little under 10 miles, the greatest breadth
1J miles, opposite the mouth of the Arkaig, and the average breadth
three-fifths of a mile. The greatest depth is 531 feet, and the mean
depth 229 feet. The loch has a superficial area of nearly 6 square miles,
and drains directly an area of about 58 square miles, but as it receives
the outflow from Loch Arkaig, the total drainage area is nearly 124
square miles. The overflow of Loch Lochy is carried by the river
Lochy into Loch Linnhe.

The survey of the loch occupied from April 28 to May 1, 1903; the
height of the surface above sea-level on commencing the survey was

358 BATHYMETRICAL SURVEY OF

found to be 94-24 feet, as compared with 93*2 feet observed by the
officers of the Ordnance Survey on July 1, 1870. Loch Lochy contains
37,726 millions of cubic feet of water, or nearly 50 per cent, more than
Loch Arkaig, the second largest loch in the basin.

At the north end a small basin, called Ceann Loch, measuring one-
half by one-third of a mile, and having a maximum depth of 66 feet, is
cut off from the main loch by a narrow channel** in which the greatest
depth is 40 feet.

The main loch is a simple basin, with the U-shaped section charac-
teristic of glacier-formed lakes. All the contours are continuous, those
at 50 and 100 feet enclosing areas little less than the total length of the
loch. The area enclosed by the 200-feet contour measures 6| miles in
length, by the 300-feet contour 4J miles, and by the 400-feet contour a
little over 3 miles in length. The 500-feet contour encloses a very
small area, one-third of a mile long by one-eighth of a mile broad,
just about the middle of the loch, and includes the deepest sounding in
531 feet. From opposite the mouth of the river Arkaig to the outflow,
the loch shallows rapidly and the contours are irregular.

The following table gives the approximate areas between the
consecutive contour-lines drawn in at intervals of 100-feet, with the
percentages to the total area of the loch : —

0 to 100 feet 923 acres 24 -4 per cent.

100 „ 200 ,, 937 „ 24-8

200,, 300 „ 651 ,, 17-2

300,, 400 ,, 571 „ 15-1

400,, 500 „ 678 „ 17'9
Over 500 , 23 . 0'6

3783 , 100-0

The flat-bottomed character of the basin is indicated by the
comparatively large area covered by water between 400 and 500 feet
in depth, an area greater than in the two shallower zones; the zone
between 100 and 200 feet, also, is rather larger than the shore zone.

Temperature Observations * — The surface temperature varied from
43°-5 Fahr. to 42°-l. A series taken on April 29 showed the small
range from the surface to 425 feet of only l°-2. It will be seen from

* During the past twenty years Sir John Murray has taken many temperature obser-
vations in Loch Lochy, and has published and discussed the results in the following papers,
to which the reader is referred for further details : (1) " On the Effects of Winds on the
Distribution of Temperature in the Sea- and Fresh- water Lochs of the West of Scotland,"
Scott. Geogr. Mag., vol. 4, p. 345, 1888; (2) " On the Temperature of the Salt- and Fresh-
water Lochs of the West of Scotland, at Different Depths and Seasons, during the years
1887 and 1888," /Voc. Roy. Soc. Edin., vol. 18, p. 139, 1891; (3) "Some Observations on
the Temperature of the Water of thu Scottish Fresh-water Lochs," Scott. Geogr. Mag.,
vol. 13, p. 1, 1897.

THE FRESH-WATER LOCHS OF SCOTLAND. 359

the table that the change is very gradual, but quickest in the upper
50 feet, where half of the total range occurs : —

Surface 42°'7 Fahr.

10 feet 42°-5 „

50 „ 42°'l „

100 „ 42°-l „

150 „ 4l°-9 „

200 „ 41°-7 „

300 „ 41°-7 „

350 ,, 41°-6 „

400 „ 4l°-5 „

4-_V, „ 41°'5 „

Loch Arkaig (see Plate LXXXIV.). — Loch Arkaig is a long, narrow,
curved loch, running nearly due east and west, the lower end about
1 mile west of Loch Lochy and 10 miles north of Fort William.

The lower part of the loch is well wooded, picturesque, and romantic,
with hills to north and south reaching well over 2000 feet in height
(see Fig. 53). The upper part is barer and grander, the mountains
exceeding 3000 feet in height. A road runs along the north side of the
loch, deteriorating towards the west end into a rough track which leads
to Loch Nevis and Loch Morar. Several wooded islands enhance the
charm of the scenery, and on one of these is one of the few nesting-
places of the osprey, still occupied by the birds at the time the survey
was made. There is very good fishing in Loch Arkaig, and lake trout
up to 10 Ibs. in weight were taken from the loch while the survey was
going on.

Loch Arkaig is 12 miles long, of somewhat irregular outline, but
broadest in the middle parts and tapering towards each end. The
greatest breadth is nearly a mile, the mean breadth half a mile. The
maximum depth is 359 feet, the mean depth 152| feet. The surface has
an area of 6J square miles, and the loch drains an area of 88 square
miles. The volume of water is estimated at 26,573 millions of cubic
feet.

No large loch drains into Loch Arkaig, but several very small lochs
do so, the largest being Loch a' Bhlair, a mile to the north. The chief
streams enter at the west end, where a short river brings the drainage
of Glens Pean and Dessary, and on the south side, where the stream
from Glen Camgharaidh enters near the upper end, and that from Glen
Mallie near the lower end. Only mountain torrents enter on the north.
The river Arkaig, a mile long, conveys the overflow of Loch Arkaig
into Loch Lochy.

When surveyed, in the middle of June, 1902, the height above sea-
level was found to be 139*0 feet; the officers of the Ordnance Survey
found the elevation to be 139-8 feet above the sea on July 10, 1869.

The basin of Loch Arkaig is nearly simple, the slight irregularities

360

BATH Y METRICAL SURVEY OF

doubtless correlated with the curving outline. The contours at 50 feet
and 100 feet are continuous. A little over 2 miles from the west end of
the loch there is an abrupt narrowing, and the loch continues narrow to
the end. Corresponding with this the 200-feet contour is broken into
two basins. In the narrow western part is a separate 200-feet basin,
with a maximum depth of 262 feet; this is only separated from the

FIG. 53. LOCH ARKAIG, FROM THE EAST END.

(Photograph by Mr. James Chinnley.)

main 200-feet basin by a slight shallowing to 183 feet. The main 200-
feet basin is about 8 miles long ; it includes three areas of over 300 feet,
which, however, are only separated by very slight shallo wings. The
largest of these 300-feet areas is about 2 miles long, is situated just
about the middle of the loch, and includes the maximum depth of 359
feet. The others, further to the east, are close together, and of very
slight extent. Though the wide portion of the loch, fully 9 miles in
length, forms a simple basin, there is not the well-marked U -section
found in typical glacier-formed lochs (see cross-section E-F on map).

THE FRESH- WATER LOCHS OF SCOTLAND. 361

The following table gives the approximate areas between the
contour-lines laid down at intervals of 100 feet, with the percentages
to the total area of the loch, and shows a gradually decreasing area
with increasing depth : —

0 to 100 feet 1412 acres

100 „ 200 „ 1257 „

200 „ 300 „ 1073 ,,

Over 300 , 253 ,

3995 ,, 100-0

Through the kindness of Mr. Thomas Honeyman, factor to Cameron
of Lochiel, we have inspected a bathymetrical chart of Loch Arkaig,
based upon soundings taken in 1889 by an officer in the German army
named Sandier. The chart is drawn to the scale of 1 J inches to the mile,
and the soundings are given in fathoms. A comparison of Sandler's
map with the Lake Survey map shows that — (1) Sandler's soundings are
much less numerous than those taken by the Lake Survey, and many of
his lines were taken in zigzag fashion instead of running at right angles
to the axis of the loch; (2) though there is a general agreement
between the two maps, the Lake Survey map shows as a rule rather
deeper water, position for position; for instance, taking the deepest
sounding on each of Sandler's lines, and placing it approximately on
the Lake Survey map, deeper soundings occur in the vicinity; thus
Sandler's deepest sounding in 55 fathoms (330 feet) approximates to the
Lake Survey maximum in 359 feet.

Temperature Observations. — The surface temperature in the centre
of the loch varied from 48°'3 Fahr. to 51°'5 during the three days of the
survey; near shore it reached 52°-3 on June 13. A series taken in the
main basin on June 11 showed a range of 4°-7 from the surface to 280
feet, the greatest variation being observed in the superficial layers of
water, as shown in the accompanying table: —

Surface 49° '4 Fahr.

10 feet "... 48°-9

25 „ 47°'5

50 „ 46°'5

100 ,, 45°-5

150 „ 45°-0

200 „ 44°-9

250 „ 44°7

280 „ 44°7

Loch P attack (see Plate LXXXIX.).— Loch Pattack (or Pattaig) lies
at a considerable elevation among the mountains which separate Loch
Ericht from Loch Laggan. It is only about 2 miles distant from Loch
Ericht, though it belongs to a different drainage system, draining by

362 BATHYMETRICAL SURVEY OF

the river Pattack, some 9 miles long, into the upper end of Loch Laggan.
It is a loch of somewhat irregular form, about a mile long by half a mile
broad, its long axis running nearly north-east and south-west. The
maximum depth is 58 feet, and the mean depth 14 feet. The volume of
water is estimated at 106 million cubic feet. The superficial area is
about 173 acres, or fully a quarter of a square mile, and it drains an
area of 18 square miles. It receives the greater part of the drainage of
the east side of the mountain mass, of which Ben Alder (3757 feet) is
the highest peak. In this drainage area are three smaller lochs, which
were not surveyed. When surveyed in May, 1904, the height above
sea-level was estimated (from spot-levels) at 1419 feet.

The basin is quite simple, the contours roughly following the
irregular outline of the shore, and the deepest part almost in the centre
of the loch. The slopes are gentle, except opposite the mouths of the
two rivers, both of which have laid down alluvial promontories, with
small islands, from which the incline to the deepest water is rapid. The
loch is on the whole shallow, for 78 per cent, of the lake-floor is covered
by less than 20 feet of water, and 60 per cent, by less than 10 feet of
water.

Temperature Observations. — A series of temperatures, taken in the
deepest part of the loch, gave 42°-6 Fahr. at the surface, 41°-4 at 25
feet, and 40°'8 at 50 feet.

Lochan na h-Earba (see Plate LXXXV.). — The two lochs which
bear this name may have formed at no very distant date a single loch,
as suggested by the common name and by the appearance of the ground.
Be that as it may, they are now two distinct lochs, differing by nearly
10 feet in level. In April, 1873, the Ordnance Survey officers found the
elevation of the west loch to be 115T7 feet, and that of the east loch
1142-3 feet, above sea-level. They lie in a valley which runs nearly
parallel to that occupied by Loch Laggan, to the south side of that loch,
and distant from it about a mile. Hills of over 3000 feet rise close on
the east ; on the west they are separated from Loch Laggan by a ridge
of between 2000 and 2500 feet in height. The shores are for the most
part wooded.

The West Loch. — This is the larger, broader, and deeper of the two.
It lies at an elevation of about 1150 feet, some 330 feet higher than
Loch Laggan. It is fully If miles in length, rather less than one-third
of a mile in greatest breadth, and a quarter of a mile in mean breadth.
The greatest depth is 81 feet, the mean depth over 35 \ feet. It has a
superficial area of about 263 acres, or less than half a square mile, and
drains an area of fully 5 square miles. The volume of water amounts to
408 millions of cubic feet. The loch is fed chiefly by two small streams,
coming down from Beinn a' Chlachair, which unite just before entering
the loch. A stream, half a mile long, winds through a boggy flat, con-

THE FRESH- WATER LOCHS OF SCOTLAND. 363

veying the overflow to the east loch. The long narrow loch is nearly
straight. From the centre it narrows to the outflow, but southwestward
to the upper end the width is nearly uniform, the end rectangular,
straight, and a quarter of a mile across.

The basin is quite simple, none of the contour lines being broken.
The contours do not closely follow the shore-line ; they narrow more
decidedly than the outline from the centre to each end, the slopes being
much steeper towards the centre of the loch, where the sections are
U-shaped. The deepest part is rather to the east of the centre, and
it is curious to note in close proximity an elevation with only 30 feet
on it, surrounded on all sides by water exceeding 50 feet in depth.

The approximate areas between the contour-lines, and the per-
centages to the total area of the loch, are as follows : —

0 to 25 feet 102 acres 38 '7 per cent.

25,, 50 ,, 85 ,, 32-2

50,, 75 „ 67 „ 25-6

Over 75 „ 9 „ 3'5 „

263 , 100-0

Temperature Observations. — A series of temperatures at the deepest
part of the loch showed a range of 4°-8 Fahr. from top to bottom. The
greater part of this was in the upper 10 feet, the difference between 10
and 60 feet being only 1°, as shown in the following table : —

Surface 49°'9 Falir.

10 feet " ... ... 46°-l „

20 „ 45°-8 „

60 „ 45°'l „

Near shore the surface temperature was as high as 53°'4.

The East Loch. — This is about half a mile distant from the west
loch, and nearly 10 feet lower, about 1140 feet above the sea. It is 1J
miles long, a quarter of a mile in greatest breadth, and averages just
under one-fifth of a mile in breadth. The maximum depth is 69 feet,
and the mean depth 31 feet. It has an area of about 146 acres, or nearly
a quarter of a square mile, and it drains an area extending to about 9^
square miles, including that draining into the west loch. The volume
of water is 191 millions of cubic feet, or less than half the volume of the
west loch. The chief feeder is the stream from the west loch. There
enters also at the upper end a branch of the Allt na Magha, the stream
which has laid down the delta now separating the two lochs. About the
middle of the east shore enters the small stream coming from Loch an
lubhair. The waters of Lochan na h-Earba are discharged by the Allt
Lowrag, about a mile long, into Loch Laggan.

The east loch has the same general form as the west loch, long and
narrow, broader at the upper end and tapering to the outflow. The

364 BATHYMETRICAL SURVEY OF

deep water is all towards the upper end, the lower half of the loch
being very shallow. The area enclosed by the 50-feet contour is about
half the total length of the loch, and in this part the sections are
somewhat U-shaped. A slight shoaling is observable opposite the
entrance of the stream near the middle of the eastern shore, where,
in the centre, the deepest sounding was 52 feet, with depths of 60 feet
and over both to the north-east and south-west.

Temperature Observations. — Serial temperatures in the deepest part
indicated practically the same range (5°) as in the west loch, and the
distribution of temperature was exactly similar, but all parts of the
loch were about 1° higher : —

Surface 51°'0 Fahr.

10 feet 47°'5 „

20 „ 46°-2 „

50 „ 46°-0 „

Loch Laggan (see Plate LXXXV.). — Loch Laggan is situated in the
southern portion of Inverness-shire, between the Highland and West
Highland railways, being about equally distant from the nearest points
of each. Dalwhinnie, on the Highland railway, is about 6J miles from
the upper end of the loch ; Tulloch, on the West Highland railway, is
about 6 miles from the lower end. The coach road from Kingussie to
Tulloch passes along the northern shore. The loch runs nearly north-
east and south-west, and occupies a valley lying between the very high
mountains of Badenoch on the south-east and an equally high and more
extensive mountain mass of the district of Lochaber on the west. The
loch is of the usual elongate narrow form of Scottish lochs, narrowest
in the central parts, and somewhat expanded towards each end, where
deeper water occurs. The outline is very irregular, and the bottom, as
shown by the contours, correspondingly irregular. A number of larger
and smaller islands are found in the narrower parts of the loch. The
length is a little over 7 miles, the greatest breadth two-thirds of a mile,
the mean breadth nearly half a mile, the superficial area about 1900
acres, or nearly 3 square miles. The maximum depth is 174 feet, the
mean depth 68 feet, and the volume of water about 5600 millions of
cubic feet. The loch was surveyed on June 2 and 3, 1902, when the
elevation of the lake-surface above the sea was found, by levelling from
bench-marks to be 818-6 feet ; the officers of the Ordnance Survey found
the elevation to be 818-9 feet above sea-level on October 19, 1867. The
shores are wooded nearly throughout, and the scenery wild and pic-
turesque (see Fig. 54), the mountains rising abruptly on the north side
into a series of peaks, culminating in Creag Meaghaidh, 3700 feet
high. On the south-east the high mountains are more distant, Beinn
a' Chlachair, over 3500 feet, being 4 miles from the lower end of the
loch. Close to the loch on this side, two hills, rather more than 2000

THE FRESH-WATER LOCHS OF SCOTLAND.

365

feet in height, separate it from the valley in which lies Lochan na
h-Earba. Loch Laggan drains directly an area of 34 square miles, but
since it receives the overflow from Loch Pattack and Lochan na
h-Earba, its total drainage area is nearly 62 square miles. The
principal stream entering the loch is the river Pattack, which drains
Loch Pattack and a number of smaller lochs. The Allt Lowrag brings

FIG. 54. — LOCH LAGGAN.
(Photograph by Sir John Murray. I

the overflow of Lochan na h-Earba. Near Aberarder, in the middle of
the north shore, two large burns enter, and there are many smaller
streams on this side. The river Spean issues from the loch, and flows
into the Lochy close to Loch Lochy.

Contours are drawn for every 25 feet of depth. The bottom is so
irregular that only the 25-feet and the 50-feet contours are continuous,
and follow approximately the outline of the shore. All the others are
much broken up. The 7 5 -feet contour is broken into four distinct

366 BATHYMETRICAL SURVEY OF

portions ; the largest of these approaches the west end of the loch, and
is 2J miles in length. Two lesser areas, each about two-thirds of a mile
in length, occur close together in the narrow middle part of the loch.
The 75-feet area towards the upper end of the loch is nearly 1 J miles in
length. The shallowings between these various basins are all opposite
the mouths of streams, but in one instance the stream is too small to
account for the shallowing, and other larger streams appear to have had
no effect on the contours. The largest 75-feet basin includes two areas
of over 100 feet, a very limited one in the narrow part of the loch, with
a maximum depth of 105 feet, and another, 1 J miles in length, near the
west end. This 100-feet area is at the broadest and deepest part of the
lake, and includes an area, two-thirds of a mile in length, of over 150
feet, in which two soundings of 174 feet and 170 feet respectively were
taken, with a shallowing of 155 feet between them. The two small
75-feet areas near the middle of the lake include depths of 112 and 114
feet respectively. The easternmost 75-feet area includes two very small
basins of over 125 feet, with maxima of 133 and 141 feet. Many lesser
irregularities occur. For about half a mile from the inflow of the
river Pattack the loch is very shallow, and the bottom and shores
are sandy.

The approximate areas between the contour-lines at intervals of
50 feet, with the percentages to the total area of the loch, are given
in the following table : —

0 to 50 feet 765 acres 40 '3 per cent.

50 „ 100 ,, 686 ,, 36-1

100., 150 „ 396 ,, 20-8

Over 150 , 53 . 2'8

1900 . 100-0

Temperature Observations. — The following series of temperatures,
taken towards the east end of the loch at noon on June 3, 1902,
indicates a range of only l°-2 Fahr., the greater part of the variation
occurring in the upper 10 feet of water: —

Surface ...

47° -0 Fahr.

5 feet

46°'6 ,,

10 „

4fi° •*>
to - , ,

20 .,

46°'0 „

30 ,,

45° •« ,,

50 ,,

45° -9 „

70 ,,

4-V8 ,,

100 ,

4.-> -S

Loch Ossiati (see Plate LXXXVL). — Loch Ossian (or Ouchan) is
a narrow loch in a valley running nearly north-east and south-west to
the north of Rannoch moor (see Fig. 55). It lies at a considerable

THE FRESH- WATER LOCHS OF SCOTLAND. 367

elevation, about a mile north-east of the summit of the West Highland
railway, at Corrour station, from which the loch can be seen. The
mountains rise to over 3000 feet both on the north-west and south-east.
The former solitude is now relieved, since the mansion of Sir John
Stirling Maxwell, Bart., has been built on the shore of the loch.

In form Loch Ossian is narrow, with its long axis slightly curved,
and of nearly uniform breadth throughout. It is 3J miles long, nearly

FIG. 55. LOCH OSSIAN.

(Photograph by Sir John Murray.)

half a mile in greatest breadth, and has a mean breadth of about one-
third of a mile. The greatest depth is 132 feet, and the mean depth
43 feet. It has a superficial area of just about a square mile, and a
volume of 1224 millions of cubic feet. It drains an area of nearly 10A
square miles, receiving only mountain torrents from the surrounding
hills, and flows out by the river Ossian into Loch Ghuilbinn, 2| miles
to the north. The loch was surveyed on May 14, 15, and 16, 1902,
when the height of the water above sea-level was found to be 1268'7

368 BATHYMETRICAL SURVEY OF

feet ; this is nearly identical with the level determined by the Ordnance
Survey officers on May 27, 1870, viz. 1268-6 feet.

The bottom of Loch Ossian is very uneven, the transverse, as well
as longitudinal, sections being undulate. Only the 25-feet contour
follows the line of the shore. The 50-feet contour encloses an area
2 miles in length. The south-western portion of this for three-quarters
of a mile is exceedingly narrow. Near the middle of the loch it
broadens to a quarter of a mile, and continues broad to near the out-
flow. The area over 75 feet in depth is fully a mile in length, that
over 100 feet half a mile, and that over 125 feet a quarter of a mile in
length. One mile from the upper end there is in the centre of the loch
a shoal, over which the depth is only 11 feet. The approximate areas
between the contour-lines, and the percentages to the total area of the
loch, are as follows : —

0 to 25 feet 214 acres 32 '6 per cent.

25 „ 50 „ 234 „ 35-6

50,, 75 „ 104 „ 15-8

75 „ 100 „ 72 „ 10-9

Over 100 ,, 33 ,, 5']

657 . 100-0

It will be observed that the area of the lake-floor covered by water
between 25 and 50 feet in depth is larger than the shore-zone covered
by less than 25 feet of water.

Temperature Observations. — The following temperatures taken at
1 p.m. on May 16, 1902, show a range of less than 1° Fahr. : —

Surface 44° '3 Fahr.

10 feet ... 44°-l ,,

25 „ ' 43°-7 „

50 „ 43°'8 ,,

100 ,, 43°'4 „

Loch Gliuilbinn (see Plate LXXXVIL). — Loch Ghuilbinn (or
Gulbin) is a small and relatively broad loch, lying in the midst of the
high mountainous region between Lochs Ericht, Treig, and Laggan.
The long axis runs nearly north and south. The surrounding hills rise
on all sides into peaks of well over 3000 feet. The loch is fully three-
quarters of a mile long, and nearly half a mile in greatest breadth,
with a mean breadth of a little over a quarter of a mile. The greatest
depth is 49 feet, and the mean depth over 13 feet. The superficial area
is about 146 acres, or nearly a quarter of a square mile, and the volume
85 million cubic feet. It receives the drainage of a basin extending to
29 square miles, including Loch Ossian. It is fed chiefly by the river
Ossian, which, besides bringing the overflow of Loch Ossian, receives

THE FRESH- WATER LOCHS OF SCOTLAND. 369

the drainage of considerable glens both to the east and west. Its
outflow is by the river Ghuilbinn, which flows due north about 5 miles
and enters the river Spean just below Loch Laggan. The level of the
loch is estimated, from spot-levels on the shore, to be 1160 feet above
the sea.

Loch Ghuilbinn is a simple basin. The sides slope very gently down
to 20 feet, nearly 86 per cent, of the whole area of the loch being less
than 20 feet in depth. From 20 to 40 feet the slope of the sides is
much steeper. A very small area exceeds 40 feet in depth, only about
3J per cent, of the whole. The surface temperature on May 17, 1902,
varied from 45°-0 to 45°-3 Fahr.

Loch Treig (see Plate LXXXVIIL). — Loch Treig occupies a deep
narrow valley among very high mountains in the region of Lochaber
(see Fig. 56). The valley trends nearly due north and south. The West
Highland railway runs along the east side, and Tulloch station, whence
the coach road goes off towards Kingussie, is only 2 miles from the
north or lower end of the loch. There is no road on either side of the
loch, nor is there to the south any public road nearer than Kingshouse,
at the head of Glencoe, Rannoch station being about equally distant.
The old road from Struan to the old Corrour Lodge came to the head
of the loch, but is now disused and in bad condition. A cart-road
approaches the north end of the loch. The sides of the loch are quite
uninhabited, but at or near either end are a few keepers' houses and
farms. The mountains rise very steeply on either side, those on the
west being higher, rising in a series of peaks, the highest of which
(Stob CJioir an Easain Mhoir) reaches a height of 3658 feet; on the
east the highest peak is Cnoc Dearg, 3433 feet high.

The length is a little over 5 miles, the greatest breadth three-
quarters of a mile, mean breadth just under half a mile. The maximum
depth is 436 feet, the mean depth 207 feet. The area of the loch is
nearly 2| square miles, and it drains an area of about 42 square miles.
Three streams, considerable only during floods, enter the upper end
of the loch ; the sides are unbroken by any large stream, but are scored
by the torrents which cut through the glacial debris, which here, as
at Loch Lochy, extends far up the hillsides. The overflow is carried
by the short river Treig into the river Spean at Tulloch. On May 29,
1902, when the survey was finished, Loch Treig was 787'0 feet above
sea-level ; the level was high in consequence of recent rains. On July
13, 1868, the Ordnance Survey found the height above the sea to be
783-9 feet. In volume Loch Treig comes third among the lochs of the
Lochy basin, containing 13,907 millions of cubic feet. This is more
than twice the volume of Loch Laggan, rather more than half that of
Loch Arkaig, and one-third that of Loch Lochy.

In form Loch Treig is a narrow triangle, broadest towards the south

AA.

370

BATHYMETRICAL SURVEY OF

end, and tapering all the way to the outflow. Half a mile from the
north end a rocky promontory, the Rudha Ceann Ard Thonnaich,
constricts the loch, but there is no shallowing in the narrows, where
the depth is well over 200 feet. The basin is quite simple, all the
contours approximately following the shore-line. The steep slope of
the hills is continued under water, and there is in most parts but little
beach. The axis of the loch is slightly curved, and the line of greatest
depth is nearer the west shore. The area over 400 feet deep is very
narrow, about 2 miles in length, and at both ends comes very close to
the west side, the steepest slopes in the loch being at these points. The

FIG. 56. LOCH TREIG.

(Photograph by Mr. T. N. Johnston, M.B., C.M., F.R.S.E.)

cross-sections in the middle parts of the loch, as at C-D on the map,
only show slightly the U -shape which distinguishes glacier-hollowed
lochs. The valley is so narrow, relatively to the depth of the loch,
that the steep slopes reach far towards the middle, and leave but little
comparatively level bottom. Towards the south end, where the loch
is broader, and the depth less (from 200 to a little over 300 feet), there
is a greater extent of nearly flat bottom, and the U -section is more
clearly marked. The approximate areas between the consecutive
contours at intervals of 100 feet, and the percentages to the total area
of the loch , are given in the following table : —

THE FRESH-WATER LOCHS OF SCOTLAND.

371

0 to 100 feet
100,, 200 „
200,, 300 „
300 „ 400 „
Over 400 ,

415 acres
294 „
440 „
256 „
135 „

1540 ,

27 '0 per cent.
19-1 ' „

28-6

16-6

8-7

100-0

The striking characteristic brought out by this table is the
large area of the lake-floor covered by water between 200 and 300
feet in depth — an area greater than in either of the two shallower
zones.

Temperature Observations. — At the early season when Loch Treig
was surveyed, the surface was very little warmer than the bottom, the
whole difference between the surface and 300 feet, on May 29, when the
last series was taken being only l°-7 Fahr. Five days earlier, May 24,
the difference was only 00<7. In the interval the surface had risen
in temperature l°-6, while at 300 feet the rise was only 0°-6. The three
serials are contrasted in the table appended : —

Depth in feet.

May 24,
11-30 a.m.

May 27,
9a.m.

May 29.

Surface

0 Fahr.
41-2

0 Fahr.
41-6

0 Fahr.

42-8

5

41-2

10

41-0

41-2

20

41-0

41-7

30

41-0

40

41 :4

50

411)

42:0

100

40-9

_

41-8

150

40-8

200

40-8

41-2

250

406

...

300

405

41*1

AnDubh Loclian (see Plate LXXXIX.). — A very small loch situated
about halfway between Loch Treig and the river Spean and a little to
the west of the river Treig. It lies at an elevation of 785 to 790 feet
above the sea, at the west side of an extensive deposit of gravel and
sand, hills of moderate height rising on the west shore (see Fig. 57).
It is of somewhat oblong form, diversified by many little bays, and is
shallow and weedy towards the south end. It is nearly a quarter of a
mile long, and covers an area of about 8i acres. The greatest depth is
40 feet, and the mean depth 15J feet. The volume of water amounts
to 6 millions of cubic feet. It has a drainage area of about one-sixth
of a square mile, receiving only local superficial water. It drains by
a small stream northward into the river Spean.

372

BATHYMETRICAL SURVEY OF

The basin of the loch is quite simple, the deepest part being much
nearer the north end, and the longitudinal slope is accordingly quicker
at the north end and very gradual towards the south. The temperature
of the water on October 18, 1904, was 46°-0 Fahr. at the surface, the
same at a depth of 20 feet, and only a trifling fraction less at the
bottom, 45°-8.

FIG. 57. AN DUBH LOCHAN.

(Photograph by Colonel Mainwaring.)

Lochan Lfann dd-Shrd (see Plate XC.). — A very picturesque loch,
almost halfway between Fort William and Ballachulish. It is about
5 miles south of Fort William, and is reached by a very rough road,
one of General Wade's military roads. It is a narrow loch, with its
axis running north-east and south-west. The surrounding hills are of
moderate height (1500 to 2000 feet) and grassy, except on the east,
where Mullach nan Coirean rises steeply to 3000 feet. Patches of fir
wood towards the lower end of the loch enhance the beauty of the
scene.

The loch is nearly a mile long and relatively very narrow, the
greatest breadth being only about one-sixth of a mile, and the mean
breadth one-eighth of a mile. The maximum depth is 25 feet, and the
mean depth 8J feet. The surface has an area of about 66 acres. The
volume of water is 23 millions of cubic feet. It receives the drainage

THE FRESH- WATER LOCHS OF SCOTLAND. 373

from an area of over a square mile, by small burns only, and flows out
by the Water of Kiachnish into Loch Linnhe.

At the date when surveyed (May 9, 1903) the height above sea-level
was 510*1 feet, exactly one foot lower than the elevation determined
by the Ordnance Survey officers in May 1867.

The basin of Lochan Lunn da-Bhra is broken by islands, about a
quarter of a mile from each end and nearly in the middle of the loch.
The island towards the upper end is on a bar, the greatest depth to the
north-west and south-east of it being respectively 9 and 8 feet. This
bar cuts off a separate small basin, with a maximum depth of 21 feet.
The greatest depth of the loch, 25 feet, was found not far to the north-
east of this island. North-east from the lower island it is everywhere
shallow, nowhere exceeding 7 feet.

The shores of Lochan Lunn da-Bhra are composed chiefly of gravel
with boulders, which form many heather-covered mounds. Rock is
exposed in many small spots. The stream flows out through a flattish
tract, covered with moraine mounds, about half a mile long, and rock
was seen in the channel at a distance of about 100 feet from the
loch. The promontory below Lundavra farm has been laid down by
the stream.

We were told by the local inhabitants that the loch will sometimes
freeze all over in a single night, and that small dark trout are abundant
in it. There are also some pink-coloured trout, and others silvery like
salmon.

The temperature was 48°'0 Fahr. throughout.

Loch nan Gabhar (see Plate XC.). — Loch nan Gabhar (or Gour) is
a little weedy hollow lying close to the sea-shore, and very little above
sea-level, on the west side of Loch Linnhe, nearly opposite Ballachulish.
It runs nearly east and west, and occupies the southern portion of a
large oval alluvial flat, in the midst of which rises an abrupt boss of
rock, the Torr an Duin, apparently some 70 or 80 feet in height. This
alluvial flat is surrounded by steep rocky .hills, which form the southern
shore of the loch.

The loch is of very irregular form, and interrupted by narrows,
bays, and promontories. It is fully half a mile long, one-sixth of a mile
in greatest breadth, and one-eighth of a mile in mean breadth. The
maximum depth is 5 feet, and the mean depth 2| feet. The area of the
water surface is only about 45 acres, and it receives the drainage of
13 square miles of country. The height above sea-level, on the date
when the survey was made (May 12, 1903), was 7*35 feet, as compared
with 7'5 feet observed by the officers of the Ordnance Survey on
July 19, 1867.

Loch nan Gabhar receives by the river Gour the drainage of a
considerable mountainous stretch of country, bordering Glen Gour,

374

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THE FRESH- WATER LOCHS OF SCOTLAND. 375

which extends 5 miles west from the loch, among peaks rising to
nearly 2500 feet. Two branch glens extend several* miles to the
north, and one of these brings the overflow of a small loch, Lochan
na Beinue Baine, which was not surveyed. As a consequence of the
extensive drainage area, the loch is subject to great alterations of level.
The river has laid down long spits of sand, and threatens to silt up
the loch altogether. A very short stream conveys the overflow to the
sea; there is a boss of rock on the north side where it leaves the loch.
In volume Loch nan Gabhar is the last in the basin, containing only
5 millions of cubic feet, or one million less than the volume of an Dubh
Lochan.

The temperature of the water on May 12, 1903, was 51°'5 Fahr. at
the surface and at the depth of 5 feet.

The particulars regarding the lochs in the Lochy basin are collected
together in the table on p. 374 for convenience of reference and com-
parison. From this table it will be seen that in the twelve lochs under
consideration, which cover an area of about 20 square miles, nearly
2600 soundings were taken, or an average of 214 soundings per loch,
and an average of 129 soundings per square mile of surface. The
aggregate volume of water contained in the lochs is estimated at 85,855
millions of cubic feet, or more than one-half of a cubic mile, and the
area draining into them is over 270 square miles, or nearly fourteen
times the area of the lochs.

The Red Indian at Tullocli. — The Red Lochaii, called in Gaelic by
a name which signifies " brown eye," is a very small pond lying in an
extensive morainic terrace at Fersit, near the north end of Loch Treig.
It is only about 30 yards in its longest diameter, and 5 feet deep in
the centre, is fed only by rains, and has no outflow except by percolation
through the gravel, yet its surface is maintained almost constantly at
the same level. The water is always turbid, and varies in colour from
dull green to brown or red.

It was first examined by Sir John Murray in May, 1902. The water
was then brown; the collection taken with the coarse net very pale
yellow ; that taken with the fine net a decided red. At that time there
were only two very abundant organisms — the larva of an insect,
Corethra, known as the "phantom larva," and a reddish-coloured rotifer,
Anurcea valga. There were niany other rotifera, entomostraca, and
other organisms common in ponds, but none of these were abundant
enough to be held responsible for the colour of the water. The
collection made with the fine net was examined by Dr. T. N. Johnston
and Mr. James Murray. On adding a little formalin, which killed the
animals, a blood-red sediment was deposited, which was found to
consist chiefly of A. valga and myriads of its red eggs. At that time
this species seemed to be mainly the cause of the red colour.

376 BATHYMETRICAL SURVEY OF

Examined at different seasons, the colour was found to vary. In
October, 1903, it was very red; in May, 1904, dull brown; in January,
1905, green. On all these occasions the phantom larva was about
equally abundant, and none was seen in a more advanced stage of
development. The changes of colour are doubtless correlated with the
predominance of one or another organism. The A. valya is not always
red ; in May, 1903, it was dull grey in colour. When algae are swarming,
the colour will incline to green. The colour may be affected by the
development of certain entomostraca — Diaptomus gracilis, for instance,
was very abundant, but quite colourless, in May, 1903. Later in the
year it becomes brown or red.

There are other ponds in close proximity to the Red Lochan, but
none of these shares the turbidity and reddish-brown colour. The
peculiarity is probably due to its being more closely shut in. The
surrounding rim of gravel is 14 feet above the pond at its lowest part.
There is, besides, a fringe of birch trees. The water is stagnant, which
favours the growth of certain organisms, particularly Aiturcea valga.
The blood-red larva of Cliironomus, though abundant, could have no
part in causing the red colour, as it was not in the open water, but
among the weeds and mud.

Mr. Robertson, the keeper at Fersit, to whom we are indebted for
several collections and much information about the loch, states that it
is later in freezing than the other ponds in the region. The more
active decomposition in the stagnant water would account for this.

The temperature of the water in May is about 45°'0 Fahr. It is
said that wildfowl never settle on this pond, and that the common frog
cannot live in it.

The following legend was related to Sir John Murray concerning
this Red loch : —

" Many centuries ago there lived in these parts a noted hunter named
Donnuil. In return for some services rendered to the witch of Ben-a-
Vreich, she offered to deprive the deer either of the sense of sight or of
smell, so far as he was personally concerned. He chose to have the deer
deprived of the sense of smell, ' for,' said he, ' I can easily cheat their
eye.' The witch, however, told him that in the stomach of the last stag
he would kill there would be found a ball of worsted thread. As time
passed Donnuil became ill, and, while weak in bed, his daughter told
him a fine stag was caught by the horns in some bushes near the house.
He asked for his cross-bow, and, although in bed, he shot the stag
through his bedroom window. Later on his daughter brought him a
ball of worsted which had been found in the stomach of the stag. He
knew his end was near; indeed, he died the same evening. On the
following morning the Red Lochan had appeared at the place where the
stag was killed."

This story was evidently invented to explain the origin of the Red

THE FRESH- WATER LOCHS OF SCOTLAND. 377

loch, and is of the same order as those stories invented to explain why
the fox has a bushy tail and why the serpent crawls on his belly.

NOTES ON THE BIOLOGY OF THE LOCHS IN THE LOCHY DISTRICT.
By JAMES MURRAY.

There is little peculiarity in the biology of the large lakes in the
basin, except in that of Loch Lochy. They contain the ordinary fauna
of great lakes of low temperature. Most of them were surveyed so
early in the season that the water was little above the minimum winter
temperature, and the summer Crustacea (Holopedium, Leptodora, &c.)
had not arrived. The smaller lochs were warmer, and some of those
Crustacea were present.

Loch Arkaicj. — The plankton is almost exactly that typical of large
lakes, with hardly any local peculiarity. The larva of Leptodora,
which we have rarely found, was present. A few examples of the
somewhat rare Latona setifera were found. A few species of plankton-
desmids, chiefly of the genus Staurastrum, occurred, but they were less
conspicuous than in the lochs farther west.

Loch Lochy. — Though the situation of Loch Lochy is so similar to
that of Loch Ness, and though the depth in the two lochs is comparable,
the plankton of Loch Lochy offers a remarkable contrast to that of
Loch Ness. In two different years when the lochs were examined, the
plankton in Loch Lochy was found to be much richer. The quantity
was many times greater, the species more numerous, but the special
feature was the quantity and variety of the phytoplankton. Diatoms
were very abundant. Tabellaria fenestrata, var. aster ionelloides, was
of more luxuriant growth than had been observed elsewhere, the
colonies often making more than two complete turns of the spiral.
The rare crustacean Ophryoxus gracilis (discovered in Britain in Loch
Ness by Mr. D. J. Scour field) was present. The heliozoon Clathrulina,
of frequent occurrence in our larger lakes, but usually as skeletons
merely, was here abundant and alive, the majority of the examples
having the pseudopodia fully extended.

Lochan na h-Earba. — The fauna calls for little comment. Latona
setifera was found in the west loch. Of the summer Crustacea, Holo-
pedium was in both lochs, Leptodora only in the east loch, and
Diaphanosoma brachyurum only in the west loch. Desmids were
conspicuous in both lochs, and included some species which we have
not often found.

Loch Lag y an. — The plankton is quite ordinary, except that it is
the only loch of the basin where we observed two species of Diaptomus.

378 BATHYMETRICAL SURVEY OF

One was the common D. gracilis, the other difficult to determine, owing
to the lack of fully matured examples, but almost certainly D. laticeps.

Loch Ossian and Loch Ghuilbinn. — The fauna of these lochs is in no
way peculiar. Desmids were scarce in Loch Ossian, and abundant in
Loch Ghuilbinn, where, among others, Staurastrum ophiura occurred.

Loch Treig. — Bosmina obtusirostris had a very long spine, approach-
ing the variety longispina, as found in Loch Morar. This is the only
large lake where we found the rotifer Triarthra longiseta. Skeletons
of Clathrulina were abundant. The phytoplankton was fairly rich in
species, and about a dozen Desmids were noted.

An Dubh Lochan. — This was examined very late in the season.
The chief peculiarity noted was the red colour of the Diaptomus, a
feature found in more marked degree in Lochan Lunn da-Bhra.
Desmids were abundant, and the two fine species, Staurastrum
braziliense and S. longispinum, occurred.

Lochan Lunn da-Bhra. — The Diaptomus in this loch was so deep
red that, when the nets were taken out after towing, they seemed to
contain blood.

Loch nan Gabhar. — From its shallow, weedy character, an abundant
fauna would be expected here, yet we found the collections exceptionally
poor.

THE FRESH-WATER LOCHS OF SCOTLAND. 379

LOCHS OF THE NESS BASIN.

THE basiu of the river Ness is one of the most important of Scottish
river-basins, not so much on account of the area drained, which is small
when compared with the areas drained by the Tay, Tweed, Clyde, and
Spey, for instance, but because it includes within its boundaries the
largest body of fresh water in Scotland (Loch Ness), as well as several
other large lochs and numerous small ones. The basin extends from
the mouth of the river Ness, at the junction of the inner Moray firth
with the Beauly firth, in lat. 57° 30' N. to lat. 57° N., south of Loch
Quoich, and from long. 5° 30' W., west of Loch Quoich, to long. 4° 10' W.,
south-east of Inverness. The total area, as measured with the plani-
meter on the 1-inch Ordnance Survey maps, is about 722 square miles,
and of this by far the larger portion drains into Loch Ness, for the
area draining into the river Ness, and into Loch Ashie which flows
directly into the river Ness, is only about 36 square miles. With the
exception of Loch Ashie, the superfluent waters from all the lochs
within the basin find their way into Loch Ness, so that the total area
draining into Loch Ness is about 686 square miles. The area drained
by the tributary lochs, excluding Loch Ness, is about 354 square miles,
leaving about 332 square miles draining directly into Loch Ness,
independent of the other lochs.

The principal river-systems within the basin lie to the west of Loch
Ness, viz. the Enrick, which flows through Glen Urquhart into Loch
Ness at Urquhart bay, where it is joined by the shorter river Coiltie ; «*
the Moriston, with its tributaries the Clunie and the Loyne, which
flows through Glen Moriston into Loch Ness at Invermoriston ; the
Garry, with its tributaries the Quoich and the Kingie, which flows
through Glen Garry into Loch Oich at Invergarry, and thence by the
Oich into the head of Loch Ness at Fort Augustus. To the south of
Loch Ness lies the Tarn7, also entering Loch Ness near Fort Augustus ;
and to the east lies the Foyers, with its tributaries the Breinag and the
Fechlin, which flows into Loch Ness at Foyers, and the Farigaig, which
enters Loch Ness at Inverfarigaig. Finally, to the north-east of Loch
Ness lies the Allt Mor (or Big Burn), draining Loch Ashie, which flows
into the river Ness 2 or 3 miles below Inverness, while the river Ness,
after issuing from Loch Dochfour, at the northern end of Loch Ness,

380

BATHYMETRICAL SURVEY OF

follows a winding course of about 6 miles, and pours its waters into the
Moray firth. Besides these, there are many shorter streams and burns
flowing directly into Loch Ness, or into the tributary rivers or lochs.

As will be seen from the summary table, the staff of the Lake Survey
sounded thirty- three lochs within the Ness basin, while a number of
small lochs could not be surveyed for lack of facilities. These lochs
vary in size, from the little Loch nan Losganan, covering an area of
only 7 acres, and containing only a million cubic feet of water, to the

English Mf/ea
FIG. 58. — INDEX MAP OF THE NESS BASIN.

mighty Loch Ness, covering an area exceeding 20 square miles, and
containing many thousands of millions of cubic feet of water. None of
the other lochs in the basin can be compared with Loch Ness, neither as
regards area, volume, nor depth, but still a few of the lochs are of
considerable importance. For instance, Loch Quoich is 7 miles in
length, while Loch Garry and Loch Mhor are nearly 5 miles in length,
and Loch Clunie and Loch Oich exceed 4 miles in length. Loch Quoich,
again, covers an area of nearly 3 square miles, while Lochs Garry,
Mhor, and Clunie exceed a square mile in area. Two of the lochs

THE FRESH- WATER LOCHS OF SCOTLAND. 381

(Quoich and Garry) exceed 200 feet in depth, and three other lochs
(Oich, Clunie, and nan Lann) exceed 100 feet in depth, while no fewer
than twelve others include depths exceeding 50 feet.

The basin lies almost entirely in Inverness-shire, but a small portion
of Ross-shire extends within the basin on its western border, the
boundary-line running along the centre of West Loch Loyne and for a
short distance along the centre of East Loch Loyne, and thence turning
northward it crosses Loch Clunie in its central part ; thus Lochs Loyne
and Clunie lie partly in Ross-shire and partly in Inverness-shire, while
the little Loch Beag, at the west end of Loch Clunie, is the only one
lying wholly in Ross-shire. The scenery of the basin is varied, and as
fine as anything to be seen in the Scottish Highlands : towards the north
the ground is low, but proceeding southwards it becomes more elevated,
culminating on the south-western borders in several giant peaks exceed-
ing 3000 feet in height, and on the south-eastern borders in mountains
slightly less elevated. The district is a veritable sportsman's paradise,
the deer-forests, grouse-moors, and fishings (both in river and loch) being
of the best. Trout abound in nearly every loch, with salmon and salmo
ferox in some of the larger lochs, and char in some of the smaller
lochs lying to the east of Loch Ness; the fishing in most of the lochs
is preserved.

Loch Ness (see Plates XCI. and XCIL). — Loch Ness formed the
subject of discussion at a meeting of the Research Department of the
Royal Geographical Society on January 18, 1904, and preliminary
notes on the bathymetry, temperatures, and seiches were published in
the Journal in October 1904.* Since then many temperature and
seiche observations and supplementary soundings have been taken, and
the preliminary measurements and calculations have been carefully
revised, the final results being given here. Loch Ness is one of the best
known of the larger Scottish lochs, since it forms a considerable part
(nearly one-half) of the waterway known as the Caledonian canal,
which occupies the great glen running in a north-east and south-west
direction from the Moray firth on the east coast of Scotland to Loch
Linnhe on the west coast, thus cutting Scotland into two portions.
Through the Caledonian canal thousands of visitors are carried each
season on the route between Inverness and Fort William, and the
splendid scenery of the canal and surrounding district has furnished a
theme for many pens. The absence of islands on Loch Ness is a striking
characteristic, and gives a touch of monotony to the grand and sombre
scene, as one sails up or down ; the little Cherry island, lying at the
opening of Inchnacardoch bay near the head of the loch, is invisible
except at close quarters. Castle Urquhart, on its rocky headland at

' Geogr. Joum., vol. 24, p. 420.

382

BATYHMETRICAL SURVEY OF

the south side of Urquhart bay, forms a picturesque and noteworthy
landmark.

In his journey to the Western islands of Scotland in the autumn of
1773, Dr. Johnson travelled along the shores of Loch Ness, which, he
says, is in some places 140 fathoms deep, and he remarks further that
" Natural philosophy is now one of the favourite studies of the Scottish
nation, and Loch Ness well deserves to be diligently examined." After
the lapse of 130 years this has been done, and it is proposed in this
place to summarize the results obtained by the staff of the Lake Survey
during their prolonged and " diligent examination " of Loch Ness,

FIG. 59. GENERAL VIEW OF LOCH NESS FROM BORLUM, NEAR FORT AUGUSTUS,

LOOKING NORTH-EAST.
(Photograph by Mr. G. West. From " Proc. Roy. 8oc. Edin.," by yenniaxion of the Council.)

The survey of Loch Ness was commenced 011 April 2, 1903, and by
the end of that month the preliminary survey was completed, but sub-
sequently, at various periods during the years 1903 and 1904, many
additional lines of soundings and numerous isolated soundings were
taken, some of them in connection with the work of collecting samples
of the deposits from all parts of the loch, others in connection with the
work of taking temperatures at various depths in different parts of the
loch. The total number of soundings recorded is about 1700, but
some of them have been omitted on the accompanying map to avoid
overcrowding. On April 1, 1903, the level of the surface of the loch

THE FRESH-WATER LOCHS OF SCOTLAND. 383

was determined from bench-marks as being 52-6 feet above the sea,
and to this datum-level all soundings have been reduced. A levelling-
staff was erected first at Fort Augustus, then at Invermoriston, Foyers,
and Temple piers, and the height of the water on this staff was read
daily during the progress of the survey, so that the variations in level
from day to day, and the variations from the starting-point, were readily
known. These staff readings showed that the water fell gradually but
irregularly, and by April 15 it was 1 foot lower, and by the 18th it was
H feet lower, than on April 1.

Loch Ness proper may be said to extend from the head of the
loch at Fort Augustus to the narrows at Bona ferry, a distance of 22 j
miles following the axis of maximum depth. This figure is inferior
to the length of Loch Awe (25 \ miles), and slightly in excess of the
length of Loch Lomond (22§ miles) ; if we regard the small basin of
Loch Dochfour, which is continuous with Loch Ness at its northern
end, as forming part of the loch, then the total length from the exit
of the river Ness to the head of the loch, is about 24J miles.

In this place it is proposed to include Loch Dochfour in dealing with
Loch Ness ; it is a basin about 1 \ miles in length, with a maximum
depth of 50 feet in the wide central portion, whence it narrows towards
the two ends, the southern narrows leading into Loch Ness, and the
northern termination being divided into two branches, the eastern
branch forming the river Ness, and the western branch the continuation
of the canal. With a strong south-westerly wind there is a surface
current from Loch Ness into Loch Dochfour through the narrows at
Bona ferry, and, if long continued, the water becomes banked up in
Loch Dochfour, and gives rise to a return current along the bottom into
Loch Ness ; with a strong wind from the north-east the surface current
sets in the opposite direction, i.e. from Loch Dochfour into Loch Ness.
Cut off from the western margin of Loch Dochfour, by embankments
carrying the towing-path for the canal, are two small basins, one called
Abban water, having a maximum depth of 9 feet, the other without a
distinctive name, having a maximum depth of 23 feet; they stand at
the same level as Loch Dochfour, the water evidently percolating
through the embankments.

Loch Ness may be said to be fairly uniform in breadth, though
varying to some extent, but on the whole its shore-line is very regular
when compared with other large lochs. The upper portion between
Fort Augustus and Foyers for about 10 miles is under a mile in width,
except at the opening of Glen Moriston, where the breadth slightly
exceeds a mile. The portion between Foyers and Castle Urquhart for
about 5 miles is almost exactly a mile in width, while the lower portion
between Castle Urquhart and Torr point for about 5 miles exceeds a
mile in width. The widest part of the loch is at Urquhart bay, from
the mouth of the river Enrick due east to the opposite shore, where the

384 BATHYMETRICAL SURVEY OF

width is 2 miles. The portion of the loch from Torr point to Bona
ferry for about 1J miles varies in width from a half to a quarter of a
mile, and the central portion of Loch Dochfour is about a quarter of
a mile in width. The mean breadth of the entire loch is nine-tenths
of a mile, or less than 4 per cent, of the length ; a smaller percentage of
mean breadth to length has been recorded only in Loch Shiel and Loch
Shin, with 2J and 3 per cent, respectively.

The waters of Loch Ness cover an area of nearly 14,000 acres, or 21|
square miles. Among the Scottish fresh-water lochs this is exceeded
only by Loch Lomond, which has a superficial area of nearly 27J square

FIG. 60. INCHNACARDOCH BAY, LOCH NESS, SHOWING CHEERY ISLAND AND THE

" HORSESHOE " IN THE DISTANCE.

(Photograph by Mr. G. West. From " Proc. Roy. Soc. Edin.," by permission of the Council.)

miles. As already stated the area draining directly into Loch Ness is
about 332 square miles, while its total drainage area, including the
area draining into all the tributary lochs, is about 686 square miles —
an area over thirty times greater than that of the loch.

The maximum depth observed by the Lake Survey staff in Loch
Ness was 754 feet, about a mile due south of Castle Urquhart in the
centre of the loch. A greater depth than this has been recorded in only
one Scottish loch, viz. Loch Morar, which has a maximum depth of 1017
feet, and after Loch Ness come Loch Lomond and Loch Lochy, with
maxima of 623 and 531 feet respectively.

THE FRESH- WATER LOCHS OF SCOTLAND. 385

The volume of water contained in Loch Ness is estimated at 263,000
millions of cubic feet, or 1| cubic miles. In no other Scottish loch does
the bulk of water amount to a cubic mile, in fact Loch Ness contains
about three times as much water as the two lochs which most nearly
approach it in this respect, viz. Loch Lomond with 92,800 million cubic
feet, and Loch Morar with 81,500 million cubic feet. The largest
volume of water recorded by Dr. Mill among the lakes of the Cumber-
land district is only 12,250 million cubic feet. As far as we are aware,
the volume of water contained in the large lakes of Ireland has not yet
been carefully worked out, but, taking Loch Neagh, for instance, which
is said to cover an area of 153 square miles (or seven times greater than
the area of Loch Ness), and to have a maximum depth of only 48 feet,
a rough calculation will show that the bulk of water in Loch Neagh
must be less than that in Loch Ness. It seems quite possible, therefore,
that Loch Ness may be the largest body of fresh water, not only in
Great Britain, but in the United Kingdom.

Correlated with the enormous volume of water in Loch Ness is the
high value of the mean depth, which works out at 433 feet for the entire
loch. This far exceeds that of Loch Morar, viz. 284 feet, which comes
next in this respect. The mean depth of Loch Ness is equal to 5 7 '4 per
cent, of the maximum depth — a higher percentage than has been
observed in any other large deep loch, the nearest approach to it being
in the case of Loch Avich, with a maximum depth of 188 feet and a
mean depth of 98 feet, the percentage being 52'4. It is true that in
some shallow flat-bottomed basins the percentage of mean depth to
maximum depth exceeds that in Loch Ness; as, for instance, Loch
Watten in Caithness (70 per cent.), and Loch Bruadale in Lewis (74
per cent.), but the maximum depths are here only 12 feet and 6 feet
respectively. Except for Lochs Ness and Avich, in all the deep Scottish
lochs, i.e. those having depths exceeding 100 feet, the mean depth is less
than one-half of the maximum depth, the percentage varying from 19'4
in Loch Shiel, and 19-5 in Loch Lomond, to 49-4 in Loch Lungard,
and 49-6 in Loch Suainaval (Lewis).

It has been stated that the surface of Loch Ness stands about 52
feet above mean sea-level, so that by far the greater portion of its floor
falls below the level of the sea.

An inspection of the bathymetrical map of Loch Ness shows — (1) the
comparative simplicity of the basin ; (2) the steep shore-slope throughout
the greater part of the loch ; and (3) the large area of the lake-floor
covered by very deep water. The 100-feet, 200-feet, 300-feet, 400-feet,
and 500-feet contours are continuous, and only the 600-feet and 700-feet
contours are interrupted by a shoaling opposite the entrance of the
river Foyers, probably due to the deposition of material brought down
by that river. This shoaling is covered by 515 to 524 feet of water,
and both to the north-east and south-west the bottom sinks to depths
exceeding 700 feet. BB

386 BATHYMETRICAL SURVEY OF

The 100-feet basin is about 22£ miles in length, the southern
extremity approaching to within 100 yards from the shore at the
entrance of the river Tarff, and the northern extremity extending
into the narrow part of the loch beyond Torr point, approaching to
within a quarter of a mile from Bona ferry.

The 200-feet basin is 2 If miles in length, approaching to within
150 yards from the Monastery boat-house slip at Fort Augustus, and
quite close to the south-western shore off the entrance of the river
Oich, and extending beyond Torr point on the north to within less than
a mile from Bona ferry.

The 300-feet basin is 20| miles in length, extending from less than
300 yards from the Monastery boat-house slip on the south to just
beyond Torr point, or 1J miles from Bona ferry, on the north.

The 400-feet basin is 20 miles in length, distant over a quarter of
a mile from the Monastery boat-house slip on the south, and about
three-quarters of a mile from Torr point, or over 2 miles from Bona
ferry, on the north.

The 500-feet basin is about 18^ miles in length, distant less than
a mile from the Monastery boat-house slip on the south, and about
1J miles from Torr point on the north. The southern extremity of
this basin differs somewhat from the usual truncate form, partaking
of a rectangular character.

The two 600-feet basins are separated by an interval of little over
half a mile, and are almost exactly equal in length, both of them
slightly exceeding 8 miles in length. The northern one is distant about
2 miles from Torr point, and the southern one less than 2 miles from
the Monastery boat-house slip at Fort Augustus.

The two 700-feet basins are separated by an interval of nearly
2J miles, the northern one being nearly twice as long as the southern
one, and including the maximum depth of the loch — 754 feet. The
northern basin is 6J miles in length, and distant about 2| miles from
Torr point, while the southern basin is 3J miles in length, and nearly
6 miles distant from Fort Augustus. The maximum depth recorded
in the southern basin was 739 feet near the southern end of the basin,
while towards the northern end of the basin a depth of 735 feet was
recorded, the intervening soundings being slightly shallower.

These details show how extremely symmetrical Loch Ness is in all
its bathymetrical characteristics. All the contour-lines, except the
deepest one, approach rather closer to the southern than to the northern
end of the loch, but in the case of the 700-feet contour this is reversed.

The shore-slope on both sides of the loch is nearly everywhere steep.
Gradients exceeding 1 in 1 are of frequent occurrence, and in certain
places the slope approaches the precipitous. Near the southern end
of the loch, off the south-western shore at the entrance of the river
Oich, a sounding in 204 feet was taken about 100 feet from shore, but

THE FRESH- WATER LOCHS OF SCOTLAND 387

the steepest slopes were observed off the north-eastern shore in the
vicinity of the Horseshoe craig, where a sounding in 236 feet was taken
about 100 feet from shore; another in 175 feet about 50 feet from
shore ; and, off what is known as the Cormorant rock, a sounding in
206 feet was taken about 50 feet from shore. This last-mentioned
sounding gives a gradient exceeding 4 in 1, or an angle of about 15°
from the perpendicular.

The steep shore-slope is further seen by the manner in which the
contour-lines of depth as a rule hug the shores, leaving a comparatively
very large area of the lake-floor along the central line of the loch
covered by very deep water. This is strikingly shown by the fact that
nearly one-half of the entire basin is covered by more than 500 feet of
water, and over one-third by more than 600 feet of water. In the
following table are given the approximate areas in acres between the
consecutive contour-lines drawn in at equal intervals of 100 feet, and
the percentages to the total area of the loch : —

0 to 100 feet 1892 acres 13'6 per cent.

100 „ 200 „ 1340 „ 9'6

200 „ 300 ,, 1610 „ 11-6

300,, 400 ,, 1121 „ 8-0

400,, 500 „ 1329 „ 9'5

500 ,, 600 „ 1627 „ 11-7

600,, 700 „ 2461 „ 17-7

Over 700 „ 2556 ,, 18 '3

13,936 ,, 100-0

This table brings out several interesting peculiarities when com-
pared with the similar tables published for the other large Scottish
lochs. The most remarkable point is that the two deeper zones are
larger than any of the other shallower zones, the deepest zone of all,
though the interval between the 700-feet contour and the maximum
depth is only half the usual interval between the contour-lines, being
the largest of all. Such a distribution of the depth-zones has not been
observed in any other loch, and is a reversal of the usual rule of the
shallowest zone being the largest one, though one or two exceptions to
this rule have been recorded, as, for instance, in Loch Treig, where the
zone between 200 and 300 feet is larger than either of the two shallower
zones, and in Loch Lochy, where the zone between 100 and 200 feet is
a little larger than the shore-zone. In the deepest of all Scottish lochs,
Loch Morar, the shore-zone is equal to 42 per cent, of the total area,
and the second zone between 100 and 200 feet is equal to 13 per cent.,
while of the deeper zones not one exceeds 9 per cent, of the total area.
In Loch Lomond, again, the shore-zone is equal to 68 per cent, of the
entire area, and the second zone between 100 and 200 feet is equal to
16^ per cent., while the deeper zones are in each case less than 6 per

388 BATHYMETRICAL SURVEY OF

cent. In Loch Ericht the shore-zone is equal to 34 per cent., the second
zone between 100 and 200 feet is equal to 25 per cent., and the third
zone between 200 and 300 feet is equal to 19 per cent, of the total area,
the deeper zones in each case not exceeding 10 per cent. In Loch Tay
there is a regularly decreasing percentage in the zones of depth from
the shore into deep water, the numbers for each zone at intervals of
100 feet being respectively 30, 23J, 21, 15J, 9.

Loch Quoich (see Plate XCIIL). — The largest loch in the basin after
Loch Ness. It is very nearly 7 miles in length, and occupies the upper
part of Glen Garry, which here runs east and west. It is 9 miles west
of Loch Garry, and 15 miles from Loch Oich. It is much nearer the
west coast, the head of Loch Hourn being only 4 miles distant. The
mountain peaks both north and south reach well over 3000 feet. On
the south the highest peak is Sgor Mor (3290 feet). On the north
the two peaks of Sgurr a' Mhoraire (3365 feet) and Gleourach (3395
feet) rise to the west and east of Glen Quoich, which branches north-
ward from Glen Garry about the middle of Loch Quoich. On the
north Loch Quoich is densely wooded for the greater part of its length.

Loch Quoich is of the usual elongate form of Scottish glen lochs.
Its central line is strongly curved, the central part further north than
the ends. The height of the loch above sea-level on May 6, 1903, was
556-0 feet; the Ordnance Survey officers, on August 24, 1867, found it
to be 555-3 feet. The length, measured in a straight line between the
ends, is almost exactly 6 miles; measured along the centre line it is
nearly 7 miles. The maximum breadth of three-quarters of a mile
occurs just east of the centre. The mean breadth is a little under half
a mile. The superficial area of the loch is about 1833 acres, or fully
2| square miles, and it contains 8345 millions of cubic feet of water,
more than twice the volume of Loch Garry, the loch next to it in size.

Loch Quoich drains an area of 49 square miles, which includes no
large lochs, but some very small ones which were not surveyed. Several
large burns, rising among the high mountains of the west, enter at the
head of the loch; and the Caolie water, flowing in on the north shore,
is a fair stream ; but the most important inflowing river is the Quoich,
which enters about the middle of the north side, and has here by its
delta effected a considerable narrowing of the loch. The constriction
so produced is the greater because, just opposite the mouth of the river,
a high promontory juts out more than a quarter of a mile from the
south shore. The shallowing of this constriction is but slight.

The basin of Loch Quoich is simple, with steep and nearly uniformly
sloping sides, and very little flat bottom. The contours are all con-
tinuous and approximately parallel with the shore-line, except the
200-feet contour, which is slightly interrupted by a shallowing where
the maximum is 190 feet, just west of the mouth of the Quoich. The

THE FRESH- WATER LOCHS OF SCOTLAND. 389

area of over 200 feet to the west of this is three-quarters of a mile long,
and has a maximum depth of 220 feet. The larger area of over 200
feet is 2 miles long, and extends from just west of the narrows
eastward. The area of over 250 feet lies well down the loch, coming
to within 1J miles of the outflow, and includes the maximum depth of
the loch, 281 feet. The mean depth of the loch is 104 \ feet. The
proper basin of the loch terminates three-quarters of a mile from the
lower end of the loch. At this point there is a bend at right angles to
the main axis, and there ex'tends a broad, tortuous, shallow section of
the loch, with a greatest depth of only 43 feet, and numerous small
islands.

As is shown by the narrowness of the areas enclosed by the deeper
contours, there is no marked indication of the U-shaped section of
valley lochs excavated by glaciers. The promontory opposite the river
Quoich, occurring where a great bend of the axis takes place, must
have caused a narrowing here before the delta of the Quoich was laid
down.

On May 6, 1903, the difference of temperature between the surface
and 150 feet was under 1° :— Surface, 41°-9 Fahr. ; 50 feet, 41°-2; 150
feet, 41°-0.

Loch Poulary (see Plate XCIV.). — A long, irregular, narrow loch
running east and west in Glen Garry, between Loch Garry and Loch
Quoich, about 4 miles distant from the former and 2 miles from the
latter. It is little more than a series of expansions of the river Garry,
and its limits are accordingly not easy to define. The portion surveyed
begins at Eilean Dubh, extends eastward for 1 mile as a narrow channel
varying from 9 feet to 23 feet in depth, and then expands into a little
basin half a mile long by one-fifth of a mile in greatest breadth. The
length of the whole loch is 1J miles, and the mean breadth one-tenth
of a mile. The area of the surface is about 91 acres, and the drainage
area, which includes Loch Quoich, is 82 square miles. The volume of
water is 39 millions of cubic feet. The Allt a' Ghobhain, a considerable
stream, and some small burns, enter on the north shore. From spot-
levels on the shores, the height of the loch above the sea was estimated
to be 320 feet. The greater part of the loch is shallow, but in the
eastern basin there is deeper water in the centre, forming, however,
only a narrow channel. The maximum depth is 47 feet, the mean
depth 10 feet.

There was a difference of only 1° in temperature between the
surface (53°-8 Fahr.) and a depth of 40 feet (52°-8) on September 28,
1903.

(,'arry (see Plate XCV.). — Loch Garry is one of the most
important lochs in the basin, being inferior in size only to Loch Ness

390 BATHYMETRICAL SURVEY OF

and Loch Quoich. It occupies the lower part of Glen Garry, and its
lower end is only about 3 miles west of Invergarry on Loch Oich ; its
direction is about due east and west. Glen Garry is at this part very
open, the high hills, Ben Tee, a conspicuous pyramidal hill, 2936 feet
in height, on the south, and Meall Dubh (2581 feet) and some lesser
peaks on the north, being several miles distant. The sides of the
valley rise gradually to the mountains, the lower slopes on both shores
of the loch being densely wooded.

Loch Garry is elongate, slightly curved, of nearly uniform breadth
for the greater part of its length, but in the eastern part for a mile
very irregular and shallow. Its length is 5 miles, its greatest breadth
fully half a mile, and its mean breadth one-third of a mile. Its super-
ficial area is about 1117 acres, or 1J square miles, and its contents 3794
millions of cubic feet. The drainage area, including Lochs Quoich and
Poulary, is 137 square miles. Besides the river Garry, which enters
the loch at the west end, some large streams, coming down from the
mountain-mass to the westward of Ben Tee, enter on the south, and
many smaller streams on the north. Leaving the loch, the river Garry
flows 3 miles to the east and enters Loch Oich at Invergarry.

Loch Garry, at the date of the survey (May 2, 1903), was 257-0 feet
above sea-level ; the Ordnance Survey officers on July 2, 1869, found
the elevation to be 257-8 feet above the sea.

In the character of its basin Loch Garry closely resembles Loch
Quoich, higher up in the same glen. The main part of the loch, fully
3J miles long, is a simple basin. As in Loch Quoich, there is a large
portion at the east end, one mile in length, which is quite distinct
from the basin, and is of moderate depth.

This eastern part is cut off from the main loch by a large, low,
wooded promontory, called the Garbh Eilean (Rough island), and a
sandy island (Eilean Ban), to the south-west of it. An irregular
channel, varying from 9 feet to 18 feet in depth, leads to the small
eastern basin, which has a small island at each end, and a narrow arm
running to the north. This basin has a narrow area half a mile long,
over 25 feet in depth, with a maximum depth of 43 feet. At the west
end of Loch Garry a narrow offset runs for half a mile westward,
with a depth of 5 feet at the mouth, and of 8 to 16 feet within.

The main basin shallows greatly towards each end. The 50-feet and
100-feet contours closely follow the shore, except at the ends. The 150-
feet contour encloses but a narrow area If miles long. This is a good
deal nearer the south shore in the greater part of its length, but for half
a mile at its west end it recedes far from the south shore, where the
slope from 100 to 150 feet is very gradual. A small isolated 150-feet
area, Jbased on a sounding in 159 feet, lies to the east of the main
150-feet basin, the deepest sounding in the short interval between them
being 146 feet.

THE FRESH-WATER LOCHS OF SCOTLAND. 391

Centrally, in the length of the loch, but nearer the south shore, is a
small area a quarter of a mile long, over 200 feet deep, with the
maximum sounding of 213 feet. The mean depth is 78 feet. The
contours show that the slope of the bottom is nowhere very steep, but
is steepest at the south side at the deepest part of the loch. There is
but little extent of flat bottom at depths of over 150 feet, but where
the depth is less than that, especially towards the west end, there is
a well-marked flat with steeper sides.

The temperature at the surface was 42°-4 Fahr., and at 170 feet
41°-8, a difference of only 0°-6.

Loch a' Bhainne (see Plate XCVL). — A very little loch, high up on
the hill to the north of Loch Garry, about 2 miles north of the east end
of that loch. It is roughly triangular, with the apex to the south. The
hills rise steeply from the loch to the west and north. It is fed by
streams coming from Mam a' Chroisg, and the Allt a' Bhainne flows
south-eastward 3 miles into the river Garry. The bottom is irregular,
the greater part covered by less than 10 feet of water, but there are
two holes of over 20 feet, the larger with the maximum of 28 feet
close to the east shore, the other with a depth of 27 feet to the south;
a sounding of 13 feet between the two.

It is one-third of a mile long, a quarter of a mile in greatest breadth,
and one-seventh of a mile in mean breadth. The mean depth is 10 feet.
The superficial area is about 32 acres, and the volume 14 millions of
cubic feet. The drainage area is nearly 2 square miles. The height
above sea-level was estimated at 1060 feet. The temperature at the
surface and at 20 feet was 45°-0 Fahr. on May 5, 1903.

Loch Lundie (by Garry) (see Plate XCVI.).— A small loch in Glen
Garry, on a tributary of the river Garry, about 1J miles north-west of
Invergarry, on Loch Oich. It is of irregular form, its outline broken
by various arms and promontories. A point on the west side, with an
island off the east shore (Eilean na Faoileige), cause a narrowing and
separate two expansions. From the northern expansion several narrow
arms run north-eastward. Loch Lundie is three-quarters of a mile long,
by fully one-third of a mile in maximum breadth, with a mean breadth
of one-fifth of a mile. The surface has an area of about 109 acres, and
the volume of water is 78 millions of cubic feet. The drainage area is
about 3 1 square miles. The Allt Lundie comes in on the west, and the
Aldernaig burn, soon joined by the Allt a' Bhainne from Loch a'
Bhainne, flows south into the river Garry. The height above sea-level,
measured by the Ordnance Survey on August 18, 1869, was 445-4 feet.

The contour of the bottom is very uneven. The 20-feet contour
enters both expansions, keeping closer to the west shore. In both of
the expansions there is a depth of 30 feet close to the west side. The

392 BATHYMETRICAL SURVEY OF

deepest water in the loch is close off the promontory on the west shore
and nearly in the narrows. Here is a little area over 40 feet deep, with
the maximum of 54 feet. Rock was seen at a number of points on the
east and south. There are several small islands, and one of these, north
of Eilean na Faoileige, is of rock.

The temperature on May 5, 1903, was almost uniform throughout —
at the surface, 46°-5 Fahr. ; at 40 feet, 46°-5 Fahr. ; and at 50 feet,
46°-6 Fahr.

Loch Oich (see Plate XCVII.). — An insignificant loch in point of
size, though of considerable length, Loch Oich is commercially im-
portant, as it forms the highest portion of the Caledonian canal.
As regards length, it comes fifth in the Ness basin, if we exclude the
artificial Loch Mhor.

Loch Oich is an exceedingly narrow, straight loch, with its long axis
running nearly south-west and north-east. High hills rise on the east,
and the dense woods which clothe the west shore, with the islands
on its surface, render Loch Oich extremely beautiful (see Fig. 61).

Loch Oich is 4 miles long, and has a maximum breadth of little
over a quarter of a mile, and a mean breadth of barely one-fifth of a
mile. The superficial area is about 489 acres, or three-quarters of a
square mile, and the contents amount to 890 million cubic feet of water.
This is about one-half the volume of Loch Clunie, a loch very little
longer, and only one-fourth the volume of Loch Garry.

The drainage area of Loch Oich, including as it does Lochs Quoich
and Garry, is very large, amounting to 170 square miles. The drainage
is brought chiefly by the river Garry, which enters the loch about the
middle of the west shore. Only little hill torrents come in on the east.
The out-flowing river Oich runs 4 miles north-east to Loch Ness. The
level of the loch on May 1, 1903, was found to be 106*0 feet above sea-
level; on the Ordnance Survey map the level is given as 104-8 feet
above the sea, but the date on which the observation was made is not
indicated.

The outline of Loch Oich is constricted at several points, first at
Ardrishaig, half a mile from the south end, again a mile further down
the loch, and again at the mouth of the Garry, where a great peninsula
has been made by the river, and opposite to it long narrow islands.
From the mouth of the Garry the width increases to near the overflow.
A great part of the loch, equal to 68 per cent, of the entire area, is less
than 50 feet in depth. The central part of the loch is shallowest.
Opposite the mouth of the Garry the greatest depth is 20 feet, close to
the island. There are four areas of over 50 feet. The first of these is
close to the north-east end of the loch. It is three-quarters of a mile
long, and encloses an area half a mile long over 100 feet in depth. Near
the south-west end of this 100-feet area is the maximum depth of the

THE FRKSH-WATER LOCHS OF SCOTLAND.

393

loch, 154 feet, and near the other end of the area there is a sounding of
129 feet, with a depth of only 108 feet between them. The second 50-
feet area is half a mile south-west of the river Garry, and is marked by
an isolated sounding of 57 feet. The third 50-feet area begins half a
mile from the south-west end, and extends down the loch for a mile. It
is the largest basin in the loch, but not so deep as the more northerly
one, the greatest depth in it being 133 feet. The fourth 50-feet area
is close to the upper end of the loch. It is one-third of a mile long,
and is scarcely separated £rom the larger one, as they are close together,
and the depth between is 48 feet. In this fourth basin the greatest
depth is 84 feet.

FIG. 61. LOCH OICH, LOOKING SOUTH-WEST; C ALDER BURN IN THE FOREGROUND.

(Photograph by Mr. G. Went. From " Proc. Roy. Soc. Edin.," by permission of the Council.)

Temperature Observation*. — The following serial temperatures were
taken in the deepest part of the loch, series I. on May 1, 1903, and
series II. on September 25, 1903 : —

Surface

10 feet

20

30

40

50

60

70

80

90
100
120
130

i.
44° 9
44° -9

44 -x

II.

55° -0 Fahr.
54° -0
54° -0
54° -0
53° "8
53° -8
53° 8
53° -8
53° -0
51°-9
49° '8
48^-8

394 BATHYMETRICAL SURVEY OF

The series taken in May shows a range of barely 2° from surface to
bottom, while the series taken in September shows a range of over 6°, a
fall of 2° having been recorded between 90 and 100 feet. It will be
observed that the whole body of water was warmer in September than
it was in the preceding May, the bottom reading in September being 4°
higher than the surface reading in May, while the difference between
the two bottom readings is about 6°, and between the two surface
readings about 10°.

Loch Uanagan (see Plate XCVIIL). — Loch Uanagan lies a little
more than a mile to the south of Fort Augustus, on Loch Ness. It is a
narrow little loch lying parallel to the Caledonian canal, which is one-
third of a mile to the west, and is separated from Loch Uanagan by the
Torr a Choiltry, a high ridge with steep sides, densely covered with fir
trees. This hill rises abruptly from the west side of the loch to a
height of 384 feet, some 266 feet above the surface of the water.

Loch Uanagan is half a mile long, and has a maximum breadth of
one-eighth of a mile. The superficial area is about 25 acres, and the
volume of water 18 millions of cubic feet. The drainage area is about
1J square miles. The only stream of any size flows in at the south end,
and near the north end a small burn flows out to the east, where a small
part of the loch has been cut off by the railway, and joins the river
Tarff half a mile to the north. The height of the loch above sea-level
on July 2, 1903, was 118-2 feet.

Loch Uanagan is very shallow, the greater part of it less than
10 feet deep. Only one-fifth of the area is over 25 feet in depth, the
25-feet contour enclosing a narrow area one-sixth of a mile long, nearer
to the east shore, and the maximum depth of 43 feet is near shore, the
slope here being steep. The steep slope of the hill on the west is not
continued under water, the loch on that side being shallower.

Temperature Observations. — The surface temperature on July 2,
1903, was 63°-0 Fahr., and a serial taken at 2.30 p.m. on September 24,
1903, gave the following results: —

Surface ...

55°-4 Fahr.

10 feet

54° -8

20 ,

53° -A

30 „

53° -6

40 „ ,

52°-8 „

Loch Beag (by Clunie) (see Plate XCIX.). — A small triangular loch
about a quarter of a mile west of the upper end of Loch Clunie. It is
simply an expansion of the river Clunie, and is at the same level as
Loch Clunie. It is one-third of a mile long by one-fifth of a mile
broad. The area of the surface is about 26 acres, and the drainage
area very extensive, viz. 20 square miles. The volume of water is

THE FRESH- WATER LOCHS OF SCOTLAND. 395

13 millions of cubic feet. The basin of Loch Beag is simple, the sides
gently sloping, the greatest depth, 29 feet, in the centre of the loch.
The channel connecting Loch Beag with Loch Clunie varies in depth
from 11 feet to 23 feet.

Loch Clunie (see Plate XCIX.). — Loch Clunie (or Cluanie) is a
large loch occupying Glen Clunie, which runs east and west, and is
the source of the river Moriston. The lower end is about 16 miles
distant from Invermoriston, on Loch Ness. The upper end is some
13 miles from Shiel bridge, at the head of Loch Duich, on the west
coast, but Loch Hourn is still nearer, only 10 miles as the crow flies.
High mountains rise on both sides of the loch, those on the south
reaching nearly 2500 feet, while on the north the highest peak, Sgurr
nan Conbhairean, 2 miles distant, is 3632 feet in height.

Loch Clunie is very narrow, 4J miles in length, and its central line
has a slight sigmoid curvature. The shore-line is very irregular, and
the width varies greatly at different parts. Widest in the upper part,
where the maximum breadth of half a mile occurs at two points, at the
extreme west end, and 1J miles further east, whence the loch narrows
greatly toward the east, till about a mile above the outflow the width
is only one-fifteenth of a mile. Beyond this narrow part it expands
into a distinct small basin nearly a quarter of a mile in breadth. The
mean breadth of the entire loch is just about a quarter of a mile. The
superficial area exceeds 1 square mile (about 704 acres), and the drainage
area, which includes no other lochs except Lochs Beag and Lundie, is 32
square miles. It is fed by the river Clunie and some large burns on the
north shore, very little water entering on the south shore, except the
surface drainage. The river Moriston flows out from the east end of
the loch. Considering the volume of water, which amounts to 1533
millions of cubic feet, Loch Clunie comes fourth in point of size in the
Ness basin (including Loch Ness). In point of length it comes fifth, as
Loch Mhor is about half a mile longer, though in volume about 400
million cubic feet less, than Loch Clunie.

The level of Loch Clunie on September 29, 1903, was 605-2 feet
above the sea ; the Ordnance Survey officers on October 5, 1867, found
the level to be 605-9 feet. The water might rise 4 feet above the level
on the date of the survey. Above the narrows, 1 mile from the east
end of the loch, which cut off a small basin exceeding 50 feet in depth,
the basin of Loch Clunie is a simple one. The 25 -feet contour closely
follows the shore-line, and the 50-feet contour is nearly parallel to it,
but much closer on the north, where the slope is steeper. The 100-feet
contour is parallel with the others, and encloses a relatively large area,
nearly 1| miles long by a quarter of a mile in greatest breadth. It is
broken into two parts by an unimportant shallowing of 98 feet. The
smaller western portion has a maximum depth of 119 feet; the greater

396 BATHYMETRICAL SURVEY OF

area has a maximum of 123 feet. The mean depth is 50 feet. In the
narrows the depth at the western end is 10 feet, and at the eastern end
only 6 feet, while half-way between is a hole of 23 feet. The small
basin to the east of the narrows is on the whole shallow. Almost in
the centre is a shoal where the depth is only 2 feet, and close to this,
on the north, is a sounding of 30 feet. The greatest depth in this basin,
53 feet, is between the shoal and the narrows.

Consideration of the contours and the nearly flat bottom shows that
there is the U-shaped section associated with glacier-hollowed lochs,
though, on account of the moderate depth, it is less clearly denned than
in many other large lakes.

A series of temperatures taken in the deep part of the loch showed
a uniform reading of 51°'8 Fahr. at all depths from 10 feet to 75 feet.
The bottom at 100 feet was a little cooler (51°-2), and the surface a
little warmer (52°-0), the total range being thus 0°-8.

Loch Lundie (by Clunie) (see Plate XCIX.). — A small triangular
loch lying immediately to the north of Loch Clunie, about equally
distant from either end. The long axis runs nearly east and west, and
the greatest breadth is towards the west end. The outline is very
irregular, and there are several small islands near the shore.

The height above sea-level on September 30, 1903, was found to be
681-5 feet, some 76 feet above Loch Clunie; the Ordnance Survey
officers on August 2, 1869, found it to be 681-9 feet. The length is
little under half a mile, and the greatest breadth one-fifth of a mile.
The superficial area is about 27 acres, the drainage area nearly 1 square
mile, and the contents amount to 9 millions of cubic feet. It receives
only some small burns, and is drained by a burn issuing from the south-
west corner flowing south a quarter of a mile into Loch Clunie.

Loch Lundie is of no great depth, three-fourths of the superficial
area being covered by less than 10 feet of water. The area more than
10 feet in depth is narrow, and passes obliquely across the loch. The
greatest depth of 25 feet occurs at the extreme east end of this area,
and near shore, in a narrow part of the loch.

The temperature on September 30, 1903, was the same at the surface
and at 20 feet, viz. 54°-0 Fahr.

Loch Loyne (see Plate C.). — The two lochs under this name consist
of a chain of little basins or expansions of the river Loyne, connected
by narrow channels. The valley of the Loyne lies half-way between
Glen Clunie and Glen Garry, which are 2 or 3 miles distant. On the
north the lochs are separated from Loch Clunie by Beinn Loinne, 2500
feet in height. The hills on the south, though wild and bleak, are not
so high. The main road from Tomdoun to Clunie Inns crosses between
the two lochs. The valley to the west of the road has an east-and-west

THE FRESH-WATER LOCHS OF SCOTLAND. 397

trend, but from the bridge through the east loch to Glen Moriston it
runs nearly due north-east. The east loch is much the longer, and is
also deeper.

The West Loch. — The west loch lies at a height of 719-0 feet above
the sea. It is 1J miles in length, with a maximum breadth of fully
one-third of a mile, and a mean breadth of one-fifth of a mile. It
consists of three expansions, all running south from the connecting
channel, or, in other words, the north shore is unbroken, but two pro-
montories break the south shore, separating the loch into three bays.
The west bay is extremely shallow, with a maximum of 6 feet. Two
islands lie off the mouth of the river, and round these and to the north
the loch is overgrown with weeds. The channel joining it with the
mid bay has a minimum of 5 feet, but deepens to 9 feet in the east.
The mid bay has also a maximum of 6 feet. The channel leading east
from it is 12 feet deep. The eastern expansion deepens from west to
east, the maximum of 19 feet being close to the shore. The area of the
surface is about 153 acres, or a quarter of a square mile, and it receives
the drainage of 16 square miles. It contains 40 million cubic feet
of water. The river Loyne, of which the loch is merely a series of
expansions, conveys the overflow to the east loch, half a mile distant
and about 13 feet lower.

The surface temperature on May 4, 1903, was 47°-7 Fahr.

The East Loch. — East Loch Loyne is more than twice as long as
the west loch, and is also about twice as deep, but it is much narrower.
There are four principal expansions. The western expansion is ex-
tremely shallow, having a maximum depth of 7 feet, and on the date of
the survey, when the river was in flood, there was a strong current
through. There is an island about the middle of it. The channel
leading to the second expansion has a depth of 5 to 9 feet. The second
expansion is very small, with a maximum depth of 21 feet, and is joined
with the third basin by a channel 5 feet deep. The third basin is
much the largest, and has more claim to be called a loch, being 1J
miles in length, with a maximum breadth of fully a quarter of a mile,
and, but for some large and small islands towards the west end, is
a simple basin, with contours parallel to the shore. The area over
20 feet in depth is over half a mile long, with depths of 35 feet in two
places — the maximum for the whole loch. The easternmost basin is
narrow, two-thirds of a mile long, of uneven bottom, with greatest
depths of 20 and 21 feet. The length of the east loch, taken in a
straight line between the extreme points, is 2| miles, the greatest
breadth is little over a quarter of a mile, and the mean breadth is
about one-seventh of a mile.

The area of the surface is about 272 acres, or nearly half a square
mile, the area draining into the loch being about 24 square miles,
including the little Loch na Losguinn and West Loch Loyne. The

398 BATHYMETRICAL SURVEY OF

volume of water is 123 millions of cubic feet. The drainage is chiefly
brought by the river Loyne, only small burns contributing a share, the
largest entering close to the outflow.

The prominent points on both shores, and the large island, are
formed by mounds of boulders and gravel. The only rock seen was
at the very narrow channel, with a depth of only 2 feet, at the east end
of the largest basin. Here rock was exposed on both sides. The river
flows out between an alluvial flat on the north and mounds of glacial
debris on the south. The height above the sea was 706' 1 feet on
November 4, 1904.

The temperature of the surface was 46°-6 Fahr., and at 30 feet 46°'2.

Loch an Staca (see Plate CL). — Loch an Staca is a considerable
minor loch, of roughly triangular form, situated on the extensive
elevated area which stretches westward from Loch Ness, between Glens
Moriston and Urquhart. It is 6 miles distant from Loch Ness. Its
longer axis lies nearly north-east and south-west. The undulating
moorland rises little above the loch, except on the east, where Meall
na Criche, 2224 feet in height, sends a long ridge southward between
Lochs an Staca and na Criche.

Loch an Staca is estimated to be 1600 feet above the sea. It is
a mile long by two-fifths of a mile broad, with a mean breadth of a
quarter of a mile. The superficial area of the loch is about 163 acres,
or a quarter of a square mile, and the drainage area 1J square miles.
The volume of water is 110 millions of cubic feet.

Loch an Staca receives only local surface drainage, and the overflow
is carried into Loch Liath by a small burn. The bottom is very uneven,
a depth of only 9 feet being found almost in the centre of the loch,
with deeper water on all sides. There is a small island close to the
west shore. A great part of the bottom, equal to 74 per cent, of
the total area, is covered by less than 20 feet of water. Four little
depressions occur. The deepest, with the maximum depth of 51 feet,
is close to the east shore; another of 32 feet lieS to the south-west
of this ; one of 30 feet close to the west shore north of the island ; and
one of 30 feet in the centre of the loch, near the north end. At this
end is another island. The mean depth is 15J feet.

The surface temperature (June 2, 1904) was 56°'5 Fahr. ; at a depth
of 25 feet it was 52°-0, at 50 feet 48°-9, a total range of 7°-6.

Loch Liath (see Plate CL). — A little roundish loch about a mile
to the south of Loch an Staca, on the same plateau. It is about 100 feet
lower than Loch an Staca, the drainage from which it receives. The
axis of the loch has a north-east and south-west direction. It is barely
half a mile long by fully a quarter of a mile broad, with a mean breadth
of one-fifth of a mile. The superficial area is about 61 acres, and its

THE FRESH-WATER LOCHS OF SCOTLAND. 399

contents amount to 62 millions of cubic feet. The drainage area, which
includes Loch an Staca, is 4 square miles. Beyond the burn from Loch
an Staca, and another from the hill (2222 feet) on the west, it receives
only superficial drainage. The burn Allt Bhlair flows out to the south-
east, and, joining that from Loch na Criche, enters the river Moriston.
The basin is quite simple, the deeper water nearer the south-east side,
and the maximum depth of 55 feet towards the north-east end.

When surveyed on June 10, 1904, the level was found to be 1494-1
feet above the sea, which differs little from the level determined by the
Ordnance Survey officers on May 15, 1869, viz. 1494-4 feet.

The surface temperature was 56°-9 Fahr.

Loch nam Breac Dearga (see Plate XCL). — Situated on the high
ground to the west of Loch Ness, about 1 \ miles distant from the middle
part of that loch. It lies close to the west of Meall Fuarvounie (2284
feet high), which separates it from Loch Ness. The loch is elongate,
lying nearly north-east and south-west, and of irregular form, roughly
oblong. The surrounding moorland rises little above the loch, except
on the east, where the crags of Meall Fuarvounie rise close beside the
loch.

This loch was locally reputed to be of great depth, or even supposed
to be bottomless. Though we found it to be the deepest loch in this
elevated tract between Glen Urquhart and Glen Moriston, its depth was
not remarkable, and not greatly in excess of that of Lochs Liath and an
Staca in the same district. It is three-quarters of a mile in length,
about one-fifth of a mile in greatest breadth, and one-eighth of a mile
in mean breadth.

The superficial area is about 56 acres, and drains about two-thirds
of a square mile. It contains 60 million cubic feet of water. It is
drained by a burn running some 2 miles south-westward, into the Allt
nan Saighead (Alltsigh), which also receives the overflow of a host of
little lochs, which were not surveyed, and runs into Loch Ness. The
height above the sea was estimated at 1570 feet.

The basin is simple, but deepest toward the upper or north end.
The lower portion is all under 25 feet in depth. The areas of over
25 feet and over 50 feet pass obliquely across the loch from south to
north. The 50-feet contour encloses a narrow area, about a quarter
of a mile long, with the deepest sounding, 70 feet, in the middle of
the loch, but nearer the north end.

The surface temperature on June 1, 1904, was 52°-9 Fahr. ; at 10
feet, 52°-7 ; at 25 feet, 48°-2 ; and at 60 feet, 46°-2, giving a total range
of 6°-7, the greatest fall being one of 4°-5 between 10 and 25 feet.

Loch a Vullan (see Plate CI.). — A little loch of triangular form,
in the elevated hilly country to the west of Loch Ness, and about

400 BATHYMETRICAL SURVEY OF

6 miles distant from that loch. It is surrounded by moorland, rising
but little above the surface of the loch, except on the south, where
Meall na Criche rises in a series of low crags to the height of 2224 feet,
nearly 500 feet above the loch. The main part of the loch is triangular,
with the apex to the north. From the south-west corner an offset runs
one-eighth of a mile to the west, narrow at its beginning, and then
expanding. The triangular body of the loch is three-eighths of a mile
in length, but the greatest length, from the apex to the end of the west
offset, is rather more (nearly half a mile). The maximum breadth in
the triangle is one-sixth of a mile, the mean breadth one-tenth of a
mile. The height above sea-level was estimated from spot-levels to be
about 1750 feet.

Loch a' Vullan receives the overflow of a chain of four small lochs,
lying to the north-east. The outflow, controlled by a sluice, is by
a small burn, going through a chain of small lochs into the river
Enrick. The superficial area is about 28 acres, the drainage area two-
thirds of a square mile. The volume of water is 15 millions of cubic
feet.

There are two basins in Loch a' Vullan. The larger one, forming
the triangular part of the loch, is simple, with the contours following
the shore, the greater part less than 20 feet in depth, the maximum
depth being 27 feet. In the narrows separating the small western basin
the depth is 13 feet, and in the basin itself 21 feet. The mean depth is
12 feet.

On June 2, 1904, the temperature at the surface was 540>9 Fahr.,
and at 20 feet, 50°'0.

Loch Meiklie (see Plate GIL). — A loch of moderate size and relatively
broad, situated in Glen Urquhart, about half-way from Loch Ness to
Strath Glass, from each of which it is 5 miles distant. Glen Urquhart
is a fertile and well-wooded valley. Both north and south of the loch
the hills are densely wooded. On the north they rise gradually to over
1000 feet, while on the south they are steeper, and heights of 1700 feet
and upwards are reached little more than a mile from the loch. The
long axis runs nearly east and west; the length is just over a mile,
and the maximum breadth, towards the west end, is nearly half a
mile, the mean breadth being over a quarter of a mile. The maximum
depth, which coincides with the maximum breadth, is 45 feet, and the
mean depth 22 feet.

The area of the surface is about 200 acres, or nearly one-third of a
square mile, the drainage area relatively very great, amounting to nearly
42 square miles, and including many small lochs, of which only Loch
a' Vullan was surveyed. The river Enrick is the only important stream
flowing into Loch Meiklie, and the outflowing river, still bearing the
same name, flows into Loch Ness in Urquhart bay. The surface of the

THE FRESH- WATER LOCHS OF SCOTLAND. 401

water on October 3, 1903, was 364-9 feet above the sea; on June 22,
1867, the Ordnance Survey officers found it about 6 feet higher (371-5
feet).

In form Loch Meiklie is approximately oblong. A shallow inlet,
formed by the encroachment of the river, runs one-sixth of a mile from
the west end. The basin is quite simple, with the slopes everywhere
gentle, but steepest towards the north shore at the deepest part. Over
one-half of the whole area is less than 20 feet in depth. The volume of
water is 193 millions of cubic feet, making Loch Meiklie the ninth in
point of bulk in the Ness basin.

The surface temperature on October 3, 1903, was 53°'6 Fahr.

Loch Aslaich (see Plate CI.). — An extremely beautiful little loch,
about 5 miles west of Loch Ness, surrounded by hills of considerable
height, rising to about 2000 feet in the immediate neighbourhood of the
loch. On a picturesque wooded island in the loch the members of the
Lake Survey had their abode (in a lodge kindly lent by the proprietor),
while the lochs of the district were being examined. In form the loch
is a narrow oblong, with its long axis running north and south. It is
one-third of a mile long, with a maximum breadth of one-seventh of
a mile. Its superficial area is about 21 acres (only Lochs Dubh and
nan Losganan being smaller), and it drains an area of nearly 2 square
miles. This area includes a larger loch (Loch nam Meur), which was
not surveyed. Besides the chief feeder, the burn coming from Loch
nam Meur, two small burns enter the loch. The river Coiltie has its
origin in Loch Aslaich, and flows into the Enrick just where it enters
Loch Ness. Its volume is 10 millions of cubic feet; in this respect
Lochs Lundie (by Glume), Laide, Dubh, and nan Losganan, are
smaller. The height of the loch above the sea was estimated at 1310
feet. Fully half the superficial area is covered by less than 10 feet of
water. The area of more than 20 feet in depth forms a narrow strip
along the west side. This comes very near to the south end, and the
deepest sounding, 26 feet, is quite close inshore. The mean depth is
11 feet.

On July 2, 1904, the temperature at the surface and at 6 feet was
60°-0 Fahr., and at 18 feet, 56°-3.

Duhl, (see Plate XCI.). — A very little lochan a couple of miles
to the west of Loch Ness and 4 miles south of Glen Urquhart. The
shortest loch in the basin, but in all other dimensions the second
smallest, since Loch nan Losganan is shallower, narrower, of smaller
area and volume. It is obscurely triangular in form, its axis running
south-west and north-east, the apex to the north-east. It is situated
at a high level, estimated at 1340 feet, amid moorland, rising gradually
southward to Meall Fuarvounie (2284 feet). It is nearly one-fifth of a

cc

402 BATHYMETRICAL SURVEY OF

mile in length, and one-ninth of a mile in greatest breadth. It is only
about 8 acres in area, and drains an area of over 100 acres. Its volume
is 2 millions of cubic feet, twice that of Loch nan Losganan. It drains
by a small burn into the river Coiltie. The basin is simple, with
evenly sloping sides, and the deepest sounding of 18 feet almost in the
centre.

Loch Laide (see Plate XCII.) is a little shallow round loch,
measuring just about one-third of a mile in diameter, lying at a con-
siderable elevation among the hills to the west of Loch Ness, near its
northern end, above Abriachan, and about 1J miles distant. It is
surrounded by moorland and low hills, rising on the south side nearly
600 feet above the loch (Cam an Leitire, 1424 feet), within a distance
of half a mile. There is no bench-mark nearer to the loch than the
summit of this hill. On August 4, 1869, the Ordnance Survey officers
found the height above sea-level to be 859-8 feet.

The superficial area of Loch Laide is about 39 acres, and it drains an
area of 1^ square miles. It has a volume of water of 9 millions of cubic
feet, only two lochs in the Ness basin (Lochs Dubh. and nan Losganan)
being less in volume. It is fed chiefly by one small burn, rising some
2 miles to the south-west, and the overflow is carried by the Allt Loch
Laide into Loch Ness at Abriachan. The bottom of Loch Laide is very
uneven. The gre'atest depth, 9 feet, is found close to the east shore. In
the centre the depth is only 4 feet, and other soundings of 3 and 4 feet
are found far out. There are low islands near shore to the south and
west. The mean depth is just over 5 feet, or fully half the maximum
depth.

The surface temperature on May 20, 1904, was 52°-3 Fahr. ; at 5
feet, 51°-7; and at 8 feet, 51°-3.

Loch Tarff (see Plate XCL). — Loch Tarff is a beautiful loch of
triangular form (see Fig. 62) lying high among the hills to the east of
Loch Ness, from which it is about a mile distant, and 3 miles north-east
of Fort Augustus. There are several large and small islands, some of
which are covered with trees. Rocky hills rise on all sides, but to no
great height above the loch in the immediate neighbourhood. Beinn a'
Bhacaidh (1813 feet) on the north is 850 feet above the loch. The high
mountain range, culminating in Corrieyairack, is more distant on the
south-east. The outline is almost an equilateral triangle. The shores
are undulate. The large Eilean Ban is close to the shore on the north-
east. On April 25, 1903, the elevation of the lake-surface was 956*2
feet above the sea, almost identical with that observed by the Ordnance
Survey officers on July 17, 1866, viz. 956'3 feet. The greatest diameter
measured from north-west to south-east exceeds two-thirds of a mile.
The maximum breadth, taken at right angles to the line of greatest

THE FRESH-WATER LOCHS OF SCOTLAND.

403

diameter, is fully half a mile, the mean breadth being over one-third of
a mile. The superficial area is about 131 acres, and the contents 136
millions of cubic feet. The drainage area is rather over 1 square mile.
Some small burns come in from the hills to the north, and the overflow
is carried into the Doe burn, a mile to the south-west, and so into
Loch Ness.

Loch Tarff is shallow. Though it has a maximum depth of 89 feet,
the mean depth is only 24 feet, nearly two-thirds of the area being less
than 25 feet deep. The bottom is irregular, there being three separate
basins over 25 feet in depth. Two of these are unimportant and lie

FIG. 62. LOCH TABFF, LOOKING NORTH-EAST.

It i/ Mr. <r. West. From " Proc. Roy. Soc. Eilin.," \>y perini**ion of the Council.)

towards the south-east shore, with maximum depths of 27 and 42 feet
respectively. The largest 2 5 -feet area lies to the north-west of Eilean
Ban, and stretches from south-west to north-east nearly across the loch,
with a breadth of one-fifth of a mile. It encloses a small 50-feet area
and a very small area of over 75 feet, both to the north of the centre
and nearer the north-east shore, the maximum sounding, 89 feet, being
found about half-way between the island and a rocky point north-west
from it.

Temperature Obxeri'atinnsi. — A series of temperatures taken in the
deep part on April 25, 1903, showed a range of only 1| degrees, as
shown in the following table : —

404 BATHYMETRICAL SURVEY OF

Surface 42°-8 Fahr.

20 feet -. 42°-8 „

40 „ 42°-o ;,

80 „ - 41°'3 »

Loch Knockie (see Plate XCI.). — A loch of moderate size and very
irregular form, about a mile east of Loch Ness, opposite Invermoriston.
It is a beautiful loch, with great parts of the shores wooded, and several
tree-clad islands (see Fig. 63). It is narrow, with the axis running
nearly south-west and north-east. The shore-line is undulating. A

FIG. 63. LOCH KNOCKIE, LOOKING NORTH-EAST.

(Photograph by Mr. G. West. From " Proc. Roy. Soc. Editi.," by permission of the Council)

large broad bay runs off to the north-west, and there are several smaller
bays on the south-east shore. The length is 1J miles, the maximum
breadth half a mile, and the mean breadth one-fifth of a mile.

The superficial area is about 182 acres, or a little over a quarter of a
square mile, and the volume of water 194 millions of cubic feet. It has
a very limited drainage area, amounting to only about 1§ square miles.
No large stream flows into it, and a short burn carries the overflow into
Loch nan Lann. There is no bench-mark near, but a spot-level on the
shore indicates that the loch is a few feet less than 700 feet above the

sea.

Loch Knockie is on the whole shallow, as indicated by the low mean

THE FRKSH-WATKR LOCHS OF SCOTLAND. 405

depth, 24 J feet, and by the fact that two-thirds of the area of the loch is
less than 25 feet deep. Both ends are shallow beyond the two narrows
which constrict the loch, the deepest part in the north-east portion being
26 feet, and in the south-west portion 32 feet. Both the narrows are
20 feet deep. The central basin between the narrows is deep, and the
25-feet and 50-feet contours follow the shore and enter the west bay.
The greater part of the basin is over 25 feet deep, the 50-feet area being
nearly half a mile long, but narrow. The 75-feet basin is based on a
single sounding in 75 feet, the maximum depth of the loch.

Loch nan Lann (see Plate XCL). — A small loch of relatively great
depth, situated between Loch Knockie and Loch Ness, joined with Loch
Knockie by a short stream a quarter of a mile long. Loch nan Lann
lies due north and south, and is narrow towards the north and broad
towards the south end. There is a constriction in the middle of the
loch, with a small and shallow expansion to the north of it, and a broad
and deep basin to the south. The axis of the loch is considerably
curved. The east shore is wooded. The length is nearly three-quarters
of a mile, the greatest breadth one-third of a mile, and the mean
breadth about one-seventh of a mile. The superficial area is about
65 acres, and the contents amount to 105 millions of cubic feet. The
drainage area includes Loch Knockie, and amounts to 3| square miles.
It is fed chiefly by the burn from Loch Knockie. The outgoing stream
leaves the loch at the north extremity, and flows half a mile north-
westwards into Loch Ness.

North of the narrows the loch is deeper close to the west shore, and
the greatest depth in this part is 41 feet. South of the narrows the
expanded portion is a regular and simple basin. The contours are
fairly concentric with the sides of the basin, the slope pretty uniform
all round, but rather more gradual from 25 to 50 feet. The narrow
100-feet area is an eighth of a mile long, and is a very little to the
south-west of the centre. The maximum depth is 109 feet. The loch
is approximately 645 feet above the sea.

The temperature at the surface on April 24, 1903, was 42°-0 Fahr. ;
at 15 feet, 41°-8; at 25 feet, 41°-3; at 50 feet, 41°-0; and at 100 feet,
41°-0, the whole range being 1°.

Loch Kemp (see Plate XCL). — A small loch east of Loch Ness,
3 miles to the south of Foyers. It is of rather irregular form, roughly
oblong, with an arm running off to the north, and bays to the east and
west. The shore is entirely of rock, and it is surrounded by low hills.
The length is half a mile, the greatest breadth a quarter of a mile, the
mean breadth scarcely less (one-fifth of a mile). The superficial area
is about 68 acres, and the volume of water 77 millions of cubic feet.
The drainage area is 1J square miles. Two small burns enter to the

406 BATHYMETRICAL SURVEY OF

south and east, and the outflowing stream goes half a mile north into
Loch Ness. On April 23, 1903, the loch was 577*8 feet above sea-level;
on August 4, 1869, the Ordnance Survey officers found it to be 577*4
feet.

The bottom is flat, with a central depth of 41 feet. The 25-feet
contour closely follows the shore, but does not go into the north arm,
in which there is an isolated sounding of 25 feet. The maximum of
51 feet occurs in a little hole close to the shore, in the south-east corner
of the loch, the mean depth being 26J feet.

Temperature of the surface, 42°-0 Fahr. ; at 25 feet, 42°'0 ; at 50
feet, 41°;8.

Loch nan Eun (see Plate CHI.). — A dark and desolate tarn lying at
the foot of the wild and bare Cairn Vangie. The loch lies in a deep
valley, and a boat was with difficulty transported down the steep hill
from the road. Glen nan Eun runs here nearly east and west. The
Cumrack burn flowing out from the loch runs to the north-east and
becomes the river Foyers. The surface is about 915 feet above the sea.
The length is barely half a mile, and the greatest breadth about one-
sixth of a mile. The superficial area is about 35 acres, and the contents
15 millions of cubic feet. The drainage area is nearly 4 square miles,
and the chief feeder is the nan Eun, coming from the south-west.

Loch nan Eun is somewhat oblong, and is a simple basin of no great
depth. The slope of the bottom is steeper on the south, and very gentle
on the north. The maximum depth of 21 feet is near the south shore;
the mean depth is 10 feet.

On April 25, 1903, the temperature at the surface was 42°-5 Fahr.,
and at 20 feet, 42°'l.

Loch Killin (see Plate CHI.). — Loch Killiii lies high up among the
mountains on the east side of Loch Ness, about 10 miles east of Fort
Augustus. It is a narrow loch of moderate size, the valley which it
occupies running at that part nearly south to north. On the west the
precipitous crags of Creag Acain rise abruptly from the shore of the
loch to a height of 1000 feet above its surface. Equally high hills rise
more gradually on the east (see Fig. 64).

Loch Killin is narrow to the north and broadens to the south, the
maximum breadth of a quarter of a mile being just a quarter of a mile
from the south end. The mean breadth is about one-sixth of a mile.
The length is considerably over a mile. The loch has a superficial area
of about 130 acres, and contains 137 millions of cubic feet of water.
Loch Killin has a large drainage area, extending to 38J square miles,
the river Killin, which enters on the south, bringing the drainage of
several large glens. The river flowing out to the north is called the
Fechlin, and is one of the chief sources of the river Foyers. At the

THE FRESH-WATER LOCHS OF SCOTLAND. 407

head of the glen, 6 miles south of Loch Killin, is Loch na Lairige, which
was not visited. The height above sea-level is about 1044 feet.

Loch Killin is of very moderate depth, with a flat bottom. More
than half the area of the loch (58 per cent.) is covered by less than
25 feet of water. The area over 25 feet in depth is all south of a
little rocky point on the west shore, and is fully half a mile long, the
contour following the shore closely. The area over 50 feet in depth,
a quarter of a mile long, approaches close to the foot of the cliffs on
the west, and the maximum sounding of 67 feet is not far from shore.
The mean depth is 24 feet.

FIG. 64. LOCH KILLIN, LOOKING SOUTH-EAST.

(Photograph by Mr. G. West. From"Proc. Roy. Soc. Edin.," by permission of the Council.)

The temperature on April 24, 1903, was almost uniform throughout
—surface, 36°-9 Fahr. ; 50 feet, 36°-8.

Loch nan Losganan (see Plate CHI.). — A mere shallow pond with
a maximum depth of 7 feet. It is narrowly triangular, its axis curved,
and is narrow and elongate to the west. It lies about 4 miles south of
Foyers on Loch Ness, and is connected by a small burn with the river
Foyers. Though from its elongate form it is not quite the shortest
in the Ness basin, in all other respects it is the smallest. In length
it is nearly one-third of a mile, and its greatest breadth is one-tenth
of a mile. The superficial area is only about 7 acres, its volume only
1 million cubic feet, and its drainage area a quarter of a square mile.

The temperature of the water on April 21, 1903, was 42°-8 Fahr.

408

BATHYMETRICAL SURVEY OF

Loch Mhor (see Plate CIV.). — Loch Mhor is the reservoir for the
British Aluminium Co.'s works at Foyers. In its construction advantage
was taken of two natural lochs (Garth and Farraline). By means of
the dam at the lower end of Loch Garth, the surface of Loch Mhor may
be raised to 20 feet above the original level of Loch Farraline, the upper
loch. In summer the two lochs may subside to their original levels.
The loch is still divided into two portions by a causeway 2 miles from
the upper end, and a public road here crosses by a bridge, the water
passing by a canal underneath. The loch is rapidly forming a beach by
eating away the boulder clay of the fields. These raw cliffs of clay

FIG. 65. LOCH MHOR, SOUTH-WEST END, SHOWING THE SHORE WHEN THE WATER

IS LOW, WITH REMAINS OF DEAD TREES.

(Photograph by Mr. G. West. From " Proc. Roy. Soc. Edin.," by permission of the Council.}

are exposed when the loch is below its high level, and portions are
continually falling in.

Loch Mhor is of very irregular form, narrow and elongate, running
north-east and south-west in Strath Errick, the lower end some 2 miles
south-east of Foyers. On the west the country is moorland, with low
hills, and many patches of trees on the shore of the loch. On the east
the hills are higher, rising to mountains at the distance of a few miles.
The west shore-line is of a simple outline, with slight double sigmoid
curvature. The east shore is much broken up, several bays and arms
running south-eastward. The largest of these is in the middle of the
loch, and runs three-quarters of a mile inland.

THE FRESH-WAFER LOCHS OF SCOTLAND.

409

The loch is nearly 5 miles in length, has a maximum breadth of
nearly three-quarters of a mile, and a mean breadth of one-third of a
mile. It has a superficial area of 1§ square miles. The volume of water
is subject to great variation, being estimated at the date of the survey
(April 24 and 25, 1903) at 1134 millions of cubic feet. It drains an area
of about 21 square miles. Few streams of any importance enter the
loch. The largest are the Allt na Seabhaig, which formerly flowed
into the river Gourag, but was diverted into Loch Garth when the dam
was built, and the Aberchalder burn, which enters the large middle bay
on the east. When quite full the reservoir overflows into the Gourag.

FIG. 66. LOCH MHOR, SOUTH-EAST SHORE, WHEN THE WATER IS LOW ; ROCKS THAT

HAVE BEEN DENUDED OF THEIR PEAT COVERING EXHIBIT GLACIAL STRIATION.
(Photograph by Mr. G. We*t. From " Proc. Roy. Soc. Edin.," by permission of the Council.)

When surveyed the surface was 638-5 feet above sea-level. In accord-
ance with its artificial origin, the greater part of Loch Mhor is very
shallow ; deep water is only found in the original natural lochs. Two-
thirds of the whole area is less than 25 feet deep.

The basin formed by Loch Farraline before the surface was raised
was fully a mile in length and one-third of a mile broad, with a depth
of about 40 feet. The breadth has been very little increased by the
dam. The depth is now 60 feet. The basin is simple, with uniform
contours and gently sloping sides. The 25-feet contour encloses an
area of two-thirds of a mile long by one-fifth of a mile broad. The

410 BATHYMETRICAL SURVEY OF

50-feet area is very narrow, a quarter of a mile long, and a little east
of the central line.

The basin of Loch Garth, which was 1J miles long by nearly half a
mile broad, is of irregular shape. The main part of the loch was
oblong, but a long, curved, narrower part branched off to the south.
The depth is now 91 feet (the maximum for Loch Mhor). The 25-feet
contour almost coincides with the shore-line of the original loch. The
50-feet contour encloses an area 1J miles in length, and enters the
narrow southern branch. This area is broad for half a mile at the
north end, but from there south it is a narrow channel. The 75-feet
area is one-third of a mile long, by one-fifth of a mile broad. The mean
depth of the whole loch is 24 feet.

Temperature Observations. — Series of temperatures were taken in
Loch Garth on April 24, and in Loch Farraline on April 25. The
higher temperature of Loch Farraline might be due merely to its
being taken a day later, as the weather was warm : —

Loch Garth, April 24, Loch Farraline, April 25,

1903. 1903.

Surface 42° -0 Fahr 43° -5 Fahr.

lOfeeb 41°-8 ,, 43°'2 ,,

25 , 43° 0

30
40
55

80

— „ 42°-4

41°-2 „ 42°-0

,; 42°-o

41° -2

Loch Bran (see Plate XCL). — Loch Bran is situated in the woods
above Foyers, from which it is a mile distant. The shores are wooded,
with rock showing in places a little way from the water's edge. There
are really two basins at the same level, separated by a narrow neck of
land. The loch is very narrow, with the centre line strongly curved.
Its length, measured in a straight line, is about three-eighths of a
mile, measured round the curve, nearly three-quarters of a mile ; the
maximum breadth is one-fifth of a mile. The superficial area is about
24 acres, and the volume of water 13 millions of cubic feet. The
drainage area is only a quarter of a square mile ; the loch receives no
streams of any size. The east loch drains into the west loch, and that
into the river Foyers by a burn half a mile long. The east loch is
much the larger and deeper, but the deep area with a maximum of
50 feet is only a little hole in the middle of the loch. The greatest
depth in the west loch is 19 feet. The mean depth of the whole loch is
12J 'feet. The temperature at the surface on April 30, 1903, was 48°-6
Fahr.; at 10 feet, 46°-2 ; at 20 feet, 45°-0; at 25 feet, 42°*3 ; and at
50 feet, 42°-2.

Loch a' Choir e (see Plate CV.). — A little loch lying between Lochs

THE FRESH- WATER LOCHS OF SCOTLAND. 411

Dun na Seilcheig. and Rutkven, and draining into the latter. Low
but craggy hills border the loch on the west and north, the crags of
Creag Dearg facing the west end. The loch is of somewhat oblong
form, with the long diameter east and west. The length is nearly
two-thirds of a mile, the greatest breadth one-third of a mile, the mean
breadth one-fifth of a mile. The superficial area is about 86 acres, and
the volume of water 103 millions of cubic feet. The drainage area
is nearly one square mile. Only one stream, the Allt Bhreac, flows
in on the north, and at the east end the burn flows out towards Loch
Ruthven.

Loch a' Choire is 865 feet above the sea. The bottom forms a simple
basin, with the deeper water towards the east end. The 25-feet contour
follows the shore-line, except at one point on the north, where a sounding
of 18 feet lies far out. The 50-feet area, one-sixth of a mile in length,
lies all to the east of the centre of the loch. The maximum depth is 60
feet, and the mean depth 27 J feet. The temperature at the surface on
April 28, 1903, was 43°-5 Fahr. ; at 25 feet, 42°-5 ; and at 50 feet, 42°'5.

Loch Ruthven (see Plate CV.). — A loch of fair size, some 2J miles
east of Loch Ness, opposite Urquhart bay, and half a mile south of
Loch Dun na Seilcheig. It is a narrow loch, with its central line
much curved, but having its general direction east to west. Precipitous
wooded hills, the Torr M6r and the Torr Beag, rise abruptly from the
north shore. On the south the crags of Stac Gorm and Craig Ruthven
border the eastern part of the loch, while towards the west the ground
is lower and more open.

Loch Ruthven is very narrow in the middle, slightly expanded at the
east, and much expanded at the west end. The length is 2J miles, the
maximum breadth, close to the lower end, fully half a mile, and the
mean breadth a quarter of a mile. It has a superficial area of about
368 acres, or over half a square mile, and a volume of 180 millions of
cubic feet. The drainage area is 4 square miles. The burn from Loch
a' Choire comes in near the upper end of the loch, and there are no
other burns of any size. The outflowing stream is the river Farigaig,
which falls into Loch Ness at Inverfarigaig.

When surveyed on April 27 and 28, 1903, the loch was 2 feet below
a bench-mark, 703' 1 on the south shore at the upper end, and would
therefore be 701*1 feet above the sea. This figure is at variance with
two spot-levels on the north shore, where 687 and 688 feet are marked
near the west end, and there is no dam to account for so much difference.
The Ordnance Survey, on May 8, 1871, made the level 7004 feet, only
a few inches lower than our measurement. Loch Ruthven is on the
whole very shallow, having a mean depth of only 11 feet. The small
eastern expansion has a flattish sandy bottom, with a greatest depth
of 8 feet.

412 BATHYMETRICAL SURVEY OF

The narrow part, a mile in length, has a uniform central depth of
14 feet throughout, but in it, just three-quarters of a mile from the
upper end of the loch, is an abrupt little hole of very limited extent,
where the maximum depth of 42 feet occurs. The western basin has a
flattish bottom, with a depth of about 13 feet, and two little depressions
of 20 and 25 feet. Rock is exposed on the north shore at the bases
of the Torrs, and at several points on the south shore. Though the
rock is near all along the south shore, the beach is for the most part
of gravel and boulders. The river flows out through a grassy flat.

FIG. 67. WEST END OF LOCH RUTHVEN, LOOKING EAST.

(Photograph by Mr. G. West. From " Proc. Roy. Soc. Edin.," by permission of the Council.)

The temperature on April 27, 1903, was 45°-0 Fahr. from top to
bottom.

Loch Ashie (see Plate XCIL). — Loch Ashie is used for the water-
supply for the town of Inverness. It is about 6 miles south of the town,
and 1J miles east of Dares, on Loch Ness. It is an elongate loch of
moderate size, having the same general direction as the Great Glen.
The west shore is bordered for its whole length by Drumashie wood ;
on the east is a bare woodland stretch little higher than the loch.

Loch Ashie is If miles in length. It is nearly half a mile broad in
the middle, and narrows towards each end. The mean breadth is one-
third of a mile. Its superficial area is half a square mile, and the

THE FRESH-WATER LOCHS OF SCOTLAND.

413

volume of its water 309 millions of cubic feet. It has a drainage area
of nearly 3 square miles. Only a few very small burns go into it,
and the Allt Mor, its natural outflow at the north end, flows into the
river Ness 2 miles above the town of Inverness.

Loch Ashie forms a simple basin, with all the contours following
the line of the shore, and the sides everywhere with a uniform gentle
slope. The maximum depth of 51 feet is in the centre of the loch.
The mean depth is 21 feet.

The surface on April 14, 1903, was 717-75 feet above sea-level, the
water just lipping the sill of the sluice at the north end ; the Ordnance

i

FIG. 68. LOCH ASHIE FROM THE NORTH-EAST, LOOKING SOUTH-WEST, SHOWING

BARREN FLAT AND STONY SHORK.

(Photoyraph bi/ Mr. <f. tt'c.<t. From " Proc. Roy. Soc. Edin.," bij permwion of the Council.)

Survey, on April 6, 1871, found the level to be 716'0 feet above the sea.
On the date of the survey the temperature from surface to bottom was
41°-8 Fahr.

The details regarding the lochs in the Ness basin are collected
together in the table on pp. 414-415 for convenience of reference and
comparison. From this table it will be seen that in the thirty-three
lochs about 4400 soundings were taken, and that the aggregate area
of the water-surface is 34J square miles, so that the average number

414

BATHYMETRICAL SURVEY OF

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THE FRESH-WATER LOCHS OF SCOTLAND.

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416 BATHYMETRICAL SURVEY OF

of soundings per square mile of surface is 128. The aggregate volume
of water contained in the lochs is estimated at 280,923 millions of
cubic feet, or less than 2 cubic miles. The area drained by these lochs
is about 690 square miles, or twenty times the area of the lochs.

NOTES ON THE TEMPERATURE OF THE WATER"* IN LOCH NESS.
By E. M. WEDDERBURN, w.s., LL.B.

Regular temperature observations in Loch Ness were begun at Fort
Augustus in July, 1903, at the same time as the first limnograph to be
used in Scotland was erected. At first the temperature observations
were subsidiary to the other observations made in the loch, but gradually
their importance increased until the investigation of lake temperatures
became one of the principal studies of members of the Lake Survey
stationed on Loch Ness. The observations were originally made from
a rowing boat by means of the Pullar and Lucas sounding machines and
deep-sea reversing thermometers. An endeavour was made to take the
observations at regular hours in as nearly as possible the same positions
in the loch from day to day, but in stormy weather the keeping of the
same position during lengthy observations was attended with con-
siderable difficulty. In September, however, a small decked fishing
boat, called the Rlioda, was anchored off Fort Augustus in about 300
feet of water. The anchoring of this boat caused some anxiety, but it
was ultimately accomplished by means of a large mushroom anchor,
which, with the necessary length of chain, was put at the disposal of
Sir John Murray through the courtesy of Mr. Davidson, superintendent
of the Caledonian canal.

This boat was primarily intended to accommodate the electrical
thermometers which were installed, but it came to be very largely used
for taking observations by means of mercury thermometers. Lengthy
series of observations could be taken in comfort whatever the state of
the weather, and with great economy in time. It was possible to
use three or four sounding machines and thermometers at once, and
consequently a series of observations could be made much more
expeditiously than when only one sounding machine was used.

* The water of Loch Ness was submitted to analysis by Dr. Tetlow, who found
nothing abnormal about the water, except its softness and freedom from mineral matter,
the total solids being equal to only 2-9224 parts per 100,000 (1-9012 parts of fixed solids,
and 1-0212 parts of volatile solids); the principal constituents are sodium and calcium
chlorides, while magnesium chloride, iron, potassium, silicon, carbonic acid, and sulphuric
acid are present in traces.

THE FRESH-WATER LOCHS OF SCOTLAND. 417

The electrical thermometers were at first intended to furnish the
means of observing continuously radiation into and from the loch.
The apparatus was not altogether suitable for this purpose, and, being
the first installation of its kind in this country, many unforeseen
difficulties arose in the manipulation of the instruments, but never-
theless many valuable observations were made by its means. The
installation consisted of three platinum resistance thermometers and
a Callendar recorder. The boat-house of St. Benedict's Abbey was
made available to the Lake Survey by the Lord Abbot of the monastery,
and in it were placed the recording instruments. A four-ply cable
connected the recorder with the Rlwda, which was anchored at a
distance of about 300 yards from the boat-house. Many of the diffi-
culties which were experienced arose from this cable ; the strain of the
wind and the waves was constantly damaging it, and as the RJioda
swung round with the wind great care was necessary to prevent the
cable fouling with the anchor chain. On the Rlwda there were three
large drums, on which there were wound the leads for the resistance
thermometers. By these drums a thermometer could be lowered to any
desired depth, and then connected to the shore-cable by means of
mercury cup connections, and a continuous record of the temperature
at that depth could thus be obtained. It was intended to lower each
of the three thermometers to a different depth, and connect them
successively with the recorder, and so to get a series of readings at
these depths, but the sluggishness of the recorder made this method
of observation undesirable.

Temperature observations were taken at various points along Loch
Ness. At times members of the survey were stationed at Invermoriston,
Foyers, Inverfarigaig, Whitefield, and Dores. At other times a steam
launch was chartered, and cruises made up and down the loch, taking
observations en route, but this method of observation was very slow.
The speed of the launch was about six miles an hour, and, as the loch is
24 miles in length, about eight hours were spent in steaming alone;
assuming that six series of observations were taken, each lasting over
half an hour, the observations at one end of the loch were taken six
or seven hours later than at the other end. It was found that in this
time the distribution of temperature in the loch might alter very
greatly, and therefore observations made in this manner might give a
very erroneous idea of that distribution.

The observations in Loch Ness were discontinued by members of the
Lake Survey in September, 1904, but the work was taken over by the
monks at Fort Augustus (in particular by Father Cyril von Dieckhoff
and Father Odo Blundell), and continued by them until April, 1905,
so that the observations extend over a period of nearly two years. The
actual number of observations made in that time was about 12,000,
and these have been discussed by the writer in papers communicated

DD

418 BATHYMETRICAL SURVEY OF

to the Royal Society of Edinburgh.* The results arrived at are briefly
as follows : —

The yearly cycle of changes in a loch such as Loch Ness is very much
the same from year to year. Fig. 69 shows graphically what may be
called the typical curves for each month of the year, being drawn from
the monthly means of the temperature readings during the period of the
observations. From these curves it appears that in September there is
the greatest quantity of heat in the loch. Thereafter the loch cools
gradually till March or April, when the water again begins to gain heat.
This is the time when the mean air temperature begins to be higher than
the surface temperature. From May till August the increase in tem-
perature at various depths proceeds regularly, and the typical curves
representing the temperature of the water to a depth of 200 feet are
practically straight lines. Below that depth it is probable that the
temperature increases less rapidly in proportion to the depth, but-
even in the deepest waters of Loch Ness there is a range in temperature
of about 2° Fahr. The lowest recorded temperatures in the deepest
parts of the loch are in April, and the highest in the middle of
November. During the period in which the loch gains heat, the
most remarkable changes are those taking place at and near the surface.
Rapid changes are of frequent occurrence, and are probably due to
convection currents. On one occasion the temperature at the point of
observation rose 6° Fahr. in two minutes.

When the mean air-temperature falls below the surface temperature,
which is usually in August, the loch begins to part with its heat. This
is shown in the change of type in the typical curve for September. The
surface layers lose heat, while lower down the water still continues to
rise in temperature ; as already mentioned, the highest temperature at
700 feet was observed in November, or about three months after the
loch began to lose heat. In August the discontinuity between the upper
and lower layers of the loch usually becomes well marked. As the upper
layers of water become .colder, there is a layer at the surface of nearly
uniform temperature, and of gradually increasing depth. Below this
layer there is a sudden change of temperature — a discontinuity layer —
below which there is the colder water in the loch. As the season
advances this discontinuity layer gradually sinks lower, and the layer of
uniform temperature above it increases in depth, until finally the whole
loch is of nearly uniform temperature.

Before the discontinuity layer makes its appearance, the currents
produced by winds are distributed through the whole loch.. There is

* " The Temperature of the Fresh-water Lochs of Scotland, with special reference to
Loch Ness, with an appendix containing observations made in Loch Ness by members
of the Scottish Lake Survey," Trans. R<»j. Soc. Edin., vol. 45, p. 407 (1907); "An
Experimental Investigation of the Temperature Changes occurriug in Fresh-water Lochs,
Pror.. Rm/. fine. Edin., vol. 27, p. 2 (1907).

THE FRESH-WATER LOCHS OF SCOTLAND.

419

the surface current, directly produced by the wind, carrying the warm
surface water along with it, and the return current, to take the place
of the water blown along the loch, is spread throughout the whole depth

200 "

1 +3 +4 0-6 *£' 4-7" + S" #?* ^0° $l" 52" 53* 54*
FIG. 69. — TYPICAL MONTHLY CURVES OF TEMPERATURE IN LOCH NESS.

of the loch. But when the discontinuity layer has formed, the loch is
divided into two current systems. Above the discontinuity layer there
is the surface current produced by the wind, and the return current also
takes place above the discontinuity layer, without directly affecting the

420

BATHYMETRICAL SURVEY OF

DIRECTION Of WIND

A B - DISCONTINUITY iAYf/f
C - SURFACE CURRENT
0 - PRIMARY RETURN CURRENT
£ - SECONDARY SURFACE CURRENT
F - SECONDARY RETURN CURRENT

FIG. 70. CURRENT SYSTEMS IN A LOCH INDUCED BY WIND AT THE SURFACE.

lOOfeer

FIG. 71. TEMPERATURE VARIATIONS IN LOCH NESS AT FORT AUGUSTUS DURING

JULY AND AUGUST 1904,

THE FRESH- WATER LOCHS OF SCOTLAND. 421

deeper waters. This return current, however, acts on the water below
the discontinuity layer just as the current of wind acts on the natural
surface of the loch, and a secondary current is produced at the surface of
discontinuity. This secondary surface current is much slower than the
surface current produced by the winds, but to take the place of the
water carried along by it there is a secondary return current at the
bottom of the lake. The secondary return current is very slow, and
its existence was first suggested to the writer by experiments carried
out in a glass trough, but observations support the view taken. The
current systems thus described are shown in Fig. 70.

Another effect of the separation of the loch into two compartments
by the surface of discontinuity, is to render possible the temperature
seiche. The surface current produced by the wind transfers a large
quantity of warm water to the lee end of the loch, with the result that
the surface of discontinuity is deeper at the lee than at the windward
end of the loch. When the wind moderates or ceases a temperature
seiche is started, just as a seiche is started in a basin of water which has
been tilted. The temperature seiche was also studied experimentally,
and was made possible by superimposing a layer of paraffin on a layer
of water. By driving the paraffin to one end of the trough by a current
of air, the water, corresponding to the water below the surface of
discontinuity in a loch, received a tilt, and when the current of air
was stopped, a seiche started in the lower layer of water independently
of the upper layer of paraffin.

The temperature seiche was first described by Mr. E. R. Watson in
the autumn of 1903, and a good deal of doubt was expressed as to the
accuracy of his views, but the theory of a temperature seiche was
established by the observations taken in 1904. For a considerable
period observations were taken at Fort Augustus every two hours, so
as to obtain a continuous record of temperature. Fig. 71 is drawn from
the observations taken in July and August, 1904, and shows the tem-
perature variations at Fort Augustus at the surface and at depths of
50, 100, 150, and 200 feet. It will be observed that in July changes
at the surface, which are chiefly produced by winds, are accompanied
by similar changes at all depths, but that in August, when the dis-
continuity layer has been formed, the temperature variations at the
surface are independent of the variations at a depth of 100 feet, where
the variations are principally due to the temperature seiche.

Observations made at the two ends of the loch further support the
theory, as showing that the layer of discontinuity was in general rising
at one end when it was falling at the other end. Continuous records
obtained from the Callendar recorder are also easily explained by the
temperature seiche. Rough calculations were made of what should be
the period of this seiche, based on the assumption that the loch contained
two layers of water of different but uniform density. The observed

422 BATHYMETRICAL SURVEY OF

period varied with the time of year, according to the depth of the
discontinuity layer, and was from two to three days, which agrees
remarkably with the periods obtained by calculation.

NOTES ON THE SEICHES OF LOCH NESS.
ByE. M. WEDDERBURN, w.s., LL.B.

In June 1903, observations on seiches were begun in Loch Ness by
the erection of a Sarasin limnograph in the boat-house of St. Benedict's
Abbey, Fort Augustus. This instrument worked well during the period
it was in use, and some good records of seiches were obtained. The
largest seiche recorded by it occurred on November 21, 1903, and had
an amplitude of about 4J inches, but after about two days it was
disturbed by the starting of another seiche.

In the summer of the succeeding year a second Sarasin limnograph
was erected at Inverfarigaig, but it did not work satisfactorily — perhaps
owing to the exposed situation — and the records obtained were con-
sequently not looked upon as being entirely trustworthy, although, as
was to be expected, they pointed to a node in the neighbourhood of
Inverfarigaig.

Observations were also made by means of Forel's plemyrameter,
but owing to the exposed character of the shore all along Loch Ness,
observation by this means was very difficult. It is unfortunate that the
index limnograph subsequently used by Professor Chrystal had not been
designed while work was being carried on in Loch Ness.

The observed periods of the uninodal and binodal seiches in Loch
Ness are approximately 31-5 and 15*3 minutes respectively. Loch Ness
thus belongs to that class of basins in which the period of the binodal
seiche is less than half the period of the uninodal seiche. The periods
for Loch Ness have not been calculated according to ChrystaFs theory —
an exceedingly laborious piece of work, which it is hoped will yet be
undertaken — but the writer has every reason to believe that calculation
would agree with observation in this case also; for the basin of Loch
Ness is convex at Foyers, where the floor of the loch rises some 200
feet, and, moreover, the sudden shallowing which takes place in the
loch from Dores to Bona has the effect of increasing the ratio between
the periods of the uninodal and binodal seiches. This is seen in the
Lake of Geneva, where there is also a shallowing at one end of the
lake, and where the period of the uninodal seiche is more than double
the period of the binodal seiche.

Seiches of shorter period were also of frequent occurrence, notably
a seiche with a period of about 8*8 minutes, of which some remarkably
pure records were obtained, although they were of small amplitude.

THE FRESH- WATER LOCHS OF SCOTLAND. 423

Embroideries on the curves were common, and were attributed to a
long swell on the loch, to the wash of steamers, and frequently to the
opening of lock-gates on the canal at Fort Augustus.

With the view of gaining information on the effect of small variations
in atmospheric pressure, a Dines's sensitive barograph was obtained.*
Records from an ordinary Richard barograph had indicated sudden
barometric changes as a frequent cause of seiches, and the records of
the sensitive barograph supported this view to a certain extent, although
on some occasions the loch seemed unresponsive to changes in atmos-
pheric pressure. On other occasions* however, the limnograph record
seemed to be an accurate reproduction of the record obtained by means
of the sensitive barograph.

Loch Ness from its size proved to be rather unwieldy from the
point of view of seiches, so that when, in the summer of 1905, the
investigation of seiches was undertaken by Prof. Chrystal, he made
his headquarters on Loch Earn, and gathered much information as
to the cause of seiches from his observations.!

NOTES ON THE DEPOSITS OF LOCH NESS.

By G. W. LEE, D.SC., and L. W. COLLET, D.SC., with Analyses of
Selected Samples by A. WILSON, F.I.C.

About sixty samples of the deposits covering the floor of Loch Ness
were collected by the members of the Lake Survey staff from various
parts of the loch, and were examined according to the methods used in
the Challenger Office for the study of marine deposits.

They may be classed as follows : —

(1) Dark grey mud, from the deep basin opposite Urquhart bay ;

(2) Ferrugineous mud, from the part of the Invermoriston deep basin
opposite Horseshoe craig ;

(3) Peaty mud, from the south-west end of the Invermoriston deep
basin ;

(4) Yellow-grey day, from off Inverfarigaig and off Cherry island;
and

(5) Brown sand, from shallow water off Urquhart bay.

* The purchase of this instrument was facilitated by a grant from the Moray Bequest
to the University of Edinburgh.

f For further details the reader is referred to the following papers : — " On the Hydro-
dynamical Theory of Seiches, with a Bibliographical Sketch,", by Prof. Chrystal, Trans.
Roy. Soc. Edin., vol 41, p. 599 (1005); Calculation of the Periods and Nodes of Lochs
Earn and Treig, from the Bathymetric Data of the Scottish Lake Survey," by Prof.
Chrystal and E. M. Wedderburn, Trans. Roy. Soc. Edin., vol. 41, p. 823 (1905); "An In-
vestigation of the Seiches of Loch Earn by the Scottish Lake Survey/'; Part I. " Limno-
graphic Instruments and Methods of Observation," by Prof. G. Chrystal ; Part II. " Pre-
liminary Limnographic Observations on Loch Earn," by James Murray, Trans. Roy. Soc.
Edin., vol. 45, p. 361 (1906).

424 BATHYMETRICAL SURVEY OF

(1) Dark Grey Mud.

The eleven samples of this mud are homogeneous and coherent when
dry. A typical sample from 740 feet, opposite Urquhart bay, has the
following mineralogical composition : —

Minerals (25 per cent.), mean diameter 0*1 millimetre. Of these
particles quartz is the most abundant, often coloured red by a coating of
iron oxide. Orthoclase, chloritic minerals, and limonite are also present.
Fine washings (75 per cent.), composed of vegetable matter (15-89
per cent.) and clayey matter with fine mineral particles and limonitic
matter (59-11 per cent.).

Chemical Composition.

Total Silica ... .'. 62-36

Ferric oxide 12*27

Alumina 9'38

Lime tr.

Magnesia tr.

Loss on ignition 15*89

99-90

The high percentage of silica is due to the great proportion of quartz.
The alumina is due to the presence of felspar and clayey matter. The
defect 0-10 per cent, is probably due to the fact that the alkalies have
not been estimated.

(2) Ferrugineous Mud.

This type of sediment is limited to the part of the Invermoriston
deep basin opposite Horseshoe craig. One of the samples was found
after examination to be composed of : —

Minerals (29 per cent.), essentially represented by ferrugineous
grains, which are accompanied by quartz, orthoclase, chlorite, and
hornblende. These mineral particles are angular, and have a mean
diameter of 0-12 millimetre.

Fine washings (71 per cent.), composed of vegetable matter (18-46
per cent.), and fine minerals (52-54 per cent.) belonging to the species
mentioned above.

Chemical Composition.

Total silica 3744

Ferric oxide 24-48

Alumina 15-12

Lime 2-16

Magnesia 1-80

Loss on ignition 18*46

99-46
The defect 0-54 per cent, is to be sought for in the alkalies.

THE FRESH- WATER LOCHS OF SCOTLAND. 425

As there is no clayey matter in this sediment, and as the micro-
scopical investigation did not reveal the presence of many aluminous
minerals, the high percentage of alumina, i.e. 15' 12 per cent., is to be
explained by the fact that the ferrugineous grains are not made up of
pure iron oxide, but of a mixture of this oxide with clay.

Although manganese was not estimated in the above quantitative
analysis, it was found to be rather abundant in another sample.

(3) Peaty Mud.

This type of mud occupies a large area of the floor of the loch in the
south-west end of the Invermoriston deep basin.

In order to show the differences in composition due to increase of
depth, two descriptions will be given here.

First Sample — Depth 300 feet.

Minerals (35 per cent.), angular, mean diameter 0'2 mm. : orthoclase
and acid plagioclase, greenish chlorite in large flakes, quartz, horn-
blende, and ferrugineous matter.

Fine washings (65 per cent.), composed of vegetable matter (37*10
per cent.), and mineral particles (2 7 -90 per cent.) belonging to the
above-mentioned species.

Chemiccd Composition.

Total silica ... 47*88

Ferric oxide ... ... ... ... ... ... ... 5*58

Alumina 7'02

Lime 1'08

Magnesia ... ... ... ... ... ... ... 059

Loss on ignition ... ... .. ... ... ... 37'10

99-25
/Second ti ample — Depth 445 feet.

Minerals (10 per cent.), angular, mean diameter 0*12 mm. : ortho-
clase and acid plagioclase, quartz, chlorite, hornblende, and ferrugineous
matter.

Fine washings (90 per cent.), composed of vegetable matter (25 per
cent.) and fine mineral particles (65 per cent.) of the same species as
those mentioned under the heading : minerals, but chlorite and decom-
posed felspar are relatively more abundant.*

Chemical Composition.

Total silica 46'03

Ferric oxide 10'41

Alumina 7'61

Lime 9'64

Magnesia 1'60

Loss on ignition ... ... ... ... ... ... 24'6'~>

99-94

42f> BATHYMETRICAL SURVEY OF

Comparing the results of the investigation of these two samples, it
will be seen that as the depth increases both the percentage and the
diameter of the minerals decrease, the proportion of vegetable matter
also decreasing.

The high percentage of lime in the second analysis is probably due
to fragments of shells.

(4) Yellow-grey Clay.

One sample was taken off Cherry island in 95 feet, and eight samples
off the south-east coast, east of Inverfarigaig, in 250 feet. This is very
clayey in character, being soft to the touch and plastic when wet,
coherent when dried, and taking in the latter state a light brown streak
if rubbed with a hard smooth body.

The Cherry island sample is made up of : —

Minerals (1 per cent.), angular, mean diameter O'l mm. : quartz,
orthoclase, chlorite, and ferrugineous matter.

Fine washings (99 per cent.), composed of clay and very fine mineral

particles.

Chemical Composition.

Total silica 58'42

Ferric oxide 9'51

Alumina ... 24'58

Lime 0'52

Magnesia 3'74

Manganese ... ... ... ... ... ... ... 2*11

Copper oxide ... ... ... ... ... ... ... 0'65

Loss on ignition ..: ... ... ... ... ... 0'59

100-12

One of the eight other samples is made up of : —

Minerals (29 per cent.), angular, mean diameter O'l mm. : quartz

and decomposed felspar, with a decomposed ferrugineous mineral.
Fine washings (71 per cent.), composed of vegetable matter (4*2 per

cent.) and clay and mineral particles (66'8 per cent.).

Chemical Composition.

Total silica 50'94

Ferric acid 14'76

Alumina 19'80

Lime \ 6'58

Magnesia 3'61

Loss on ignition ... ... ... ... ... ... 4'20

99-89

In these analyses the lime and magnesia probably belonged to some
ferro-magnesian mineral, which was subsequently transformed into
what is given here as " decomposed ferrugineous mineral," the advanced
state of decomposition preventing its determination.

THE FRESH- WATER LOCHS OF SCOTLAND. 427

(5) Brown Sand.

To four samples of sediment dredged in 30 feet near the west coast
of Urquhart bay we give the name of Brown Sand. One of the samples
has the following composition : —

Minerals (69 per cent.), angular, mean diameter O2 mm., mostly
made up of quartz, coloured reddish by a coating of iron oxide.
Decomposed mica, hornblende, and plagioclase are also represented.
The sand contains a few small fragments of rocks, 1 to 3 millimetres in
diameter.

Fine washings (31 per cent.), composed of vegetable matter (4-4
per cent.) and fine mineral particles (26-6 per cent.). There is no clayey
matter.

Chemical Composition.

Total silica 77'62

Ferric oxide 3'60

Alumina ... ... ... ... ... ... ... 5*20

Lime 5'88

Magnesia 2*20

Loss on ignition 4'40

98-90

The alumina, lime, and magnesia are most likely due to the mica
and hornblende, whilst the defect of 1-10 per cent, might represent the
alkalies.

Conclusion.

Loch Ness includes two deep basins separated by a barrier formed by
the delta of the Foyers river. The muds from the south-western or
Invermoriston basin contain a large amount of vegetable or peaty
matter, brought down the lake probably by the rivers Tarff and Oich,
with mineral particles coming from the disintegration of the rocks,
transported by the streams. Small concretions of peroxide of iron and
dioxide of manganese were dredged at one station. The muds often
gave the characteristic reaction of manganese. On the slopes the muds
are sandy, and of a red-brown colour, due to the presence of oxide of
iron.

The muds from the north-eastern or Urquhart basin contain far
less vegetable matter than those from the south-western basin, which
may be due to the Foyers barrier retaining the vegetable matter in
the upper basin. In the north-eastern basin the vegetable matter
increases with the depth, which is contrary to what is observed in the
south-western basin. Off Urquhart bay the contour-lines approach
each other very closely, and the vegetable matter brought down the lake
by the river Enrick is carried towards the deeper part of the basin.
Great differences are observed in the muds from the slopes on the two
sides of the loch. On the north-western slope we find especially a red

428 BATHYMETRICAL SURVEY OF

sandy mud, coming without doubt from the washing out of the shore,
composed of Old Red Sandstone. On the south-eastern slope we have a
fine yellow clay, with fragments of rocks and large mineral particles
without vegetable matter. The deposition of the clay in this position
may be due partly to the strong prevailing westerly winds of Loch Ness
giving rise to waves and currents, which would carry the fine clayey
matter brought down by the Inverfarigaig river towards the south-
eastern shore. Three stones from a depth of 100 feet, opposite Inver-
farigaig pier, were covered with a dark ring of manganese dioxide,
marking out the line between the mud and water, as was pointed out
by Sir John Murray and Mr. Robert Irvine in their valuable paper :
"On Manganese Oxides and Manganese Nodules in Marine Deposits,"*

MIRAGES ON LOCH NESS.

A kind of mirage is one of the most familiar phenomena on Loch
Ness, especially in winter and spring. It is best seen in the morning.
Distant objects, such as the steamers plying on the lake, appear as
though raised above the surface and floating in the air.

The most constant feature of the Loch Ness mirages is seen at
promontories some miles distant. The shore-line at the promontories,
though really nearly parallel with the horizon, is caused by the mirage
to appear to form an angle with the horizon. When this angle is great
(say 60° or more), the promontories appear like overhanging cliffs.
When the angle is very acute, they seem to be suspended over the
horizon. Objects which are known to be below the horizon are brought
into view. The receding steamer, after sailing out of sight, will
reappear miles further away, raised high above the loch and looking
very large. The promontory at Dores appears as a conspicuous island
in the middle of the loch. The fathers in the Benedictine Monastery at
Fort Augustus tell that on one occasion a snow-covered mountain
appeared over the end of the loch. These phenomena are best marked
at a distance of several miles from the observer. The steamer, sailing
away from the observer, seemed, at the distance of a mile or more, to
leave the surface of the loch and sail up into the air. Signs of the
mirage were sometimes to be distinguished at lesser distances. Stand-
ing on the deck of the Lake Survey yacht Rhoda, when the eyes would
be 7 or 8 feet above the water, there could often be seen on the rocks
of the nearest parts of the shore a conspicuous horizontal line, looking
just like a high-water mark.

* Trans. Roy. Soc. Edin., vol. 37. p. 721 (1894).

THE FRESH- WATER LOCHS OF SCOTLAND. 429

In the reports of the Balatonsee Commission, mirages of a similar
nature are discussed. Von Cholnoky explains how they arise through
the formation of a lower stratum of warmer air, heated from the lake.
In shallow lakes like Lake Balaton, the mirage is essentially a summer
phenomenon. The lake remains warm during the night when the air
cools.

In Loch Ness the converse is the case. The great body of water
maintains a moderate temperature throughout the year. In summer
the lake rarely attains to 60°-0 Fahr., and so the air may frequently
remain as warm as the lake, though mirages may occur after any cold
night. In winter the lake maintains a high temperature, rarely falling
below 42°-0 or 430<0 Fahr., and thus the air will fall to a much lower
temperature almost every night, and a well-marked layer of warmer
air be formed by morning over the surface of the lake, giving rise to the
mirage.

" STORM- WEATHER " AT FORT AUGUSTUS.
Notes communicated by Dom CYRIL VON DIECKHOFF.

The general features of well-developed " storm-weather " are low
barometer, dry haze, wind usually south-east, blowing in isolated gusts
(''isolated" with regard to space and time), low strata of cloud forming
along lines parallel to the Great Glen, small cumuli forming rapidly in
the air and drifting towards the north-west, where they mass and form
large strata, often of very dark and threatening appearance. Little or
no rain falls during the perfect type, but rain often comes when it
breaks up. These small cumuli are well known as indications of
gales from the south-east, and are called by the local sailors " Pack-
merchants " (i.e. pedlars). There are various sub-species of this kind
of weather, especially one where the wind is constantly shifting in
every direction, the clouds all the while coming from the south-east.

In another type there is a north-east wind (warmer than the ordinary
north-east wind), while the clouds come from the south-east. On these
occasions the height of the lowest cloud is never much above 3000 feet.
There are often several layers at different heights, all in a north-east
to south-west direction — even alto-stratus pieces lie occasionally in this
direction ; their motion is usually very slow ; cirrus comes slowly from
the south-west.

" Storm- weather " may occur at any time of the year. The strongest
gales, or at least the fiercest gusts, which we get on the loch, come from
the south-east. On very rare occasions there has been noticed a kind
of reverse to the " storm-sky " during a north-west wind.

430 BATH YMETRICAL SURVEY OF

NOTES ON THE GEOLOGY OF THE NORTH-EAST PART OF THE NESS BASIN.
By B. N. PEACH, LL.D., F.R.S., and JOHN HORNE, LL.D., F.R.S.

Only a small portion of the Ness area has been mapped by the
Geological Survey. It is situated in the north-east part of the basin,
and includes the tract at the mouth of Loch Ness and on either side of
the river issuing from that loch. It comprises a small part of Loch
Ness, Loch Dochfour, Loch Ashie, Loch Abban, and Loch Laide.

The geological structure of the northern part of the Ness basin is
well denned. The basin is traversed by the great fault that runs along
Loch Ness, which is continued north-eastwards to Tarbat Ness, thus
giving rise to the prominent cliff bounding the Moray firth in the
Black isle. This powerful dislocation, which has been a line of weakness
in the earth's crust at successive geological periods and is evidently
related to the earthquake movements that periodically affect the Inver-
ness district at the present time, has a marked downthrow to the
south-east. The exact position of the line of fault in the Ness valley
is concealed by superficial deposits, but its course probably extends
from near the western shore of Loch Ness at Lochend, north-east by
Loch Dochfour, Duneaii cottage, and Kinmylies, to the Beauly firth
east of Kessock ferry.

The effect of this great dislocation in the Ness valley is to let down
the Old Red Sandstone strata on the south-east side against the
crystalline schists and gneisses of Dochfour hill, the Abriachan granite,
and the basal conglomerates and sandstones of Duueaii hill and
Craig Leach on the north-west. The schistose rocks of Dochfour hill,
which are pierced by the Abriachan granite, consist of quartz-biotite
granulites and felspathic gneisses traversed by numerous veins of
pegmatite. Occasional lenticles of garnetiferous hornblende-schist
are associated with the gneisses, and a band of limestone also
occurs in the schistose series at Blairnahenachrie, west-north-west of
Dochgarroch. From their lithological characters, these crystalline
schists have been referred to the Moine series of the Geological Survey,
the members of which are regarded as altered representatives of
sedimentary deposits.

The triangular area of Old Red Sandstone on the west side of the
valley of the Ness, extending from Dochgarroch north-east to Clachna-
harry, and west to the Bunchrew burn, consists of coarse conglomerates
and grits that dip to the north-west, and are overlain by sandstones,
flags, and shales. Along their western margin they are bounded by a
fault, with a downthrow to the east, which is probably a branch of the
great dislocation running along Loch Ness.

THE FRESH- WATER LOCHS OF SCOTLAND. 431

On both sides of the valley of the Ness there is abundant evidence
of intense glaciation of the region. On the elevated plateau west of the
Ness valley the direction of the ice-movement varied from 25° to 35°
north of east. The ice that issued from the Great Glen flowed more or
less parallel to the long axis of Loch Ness, that is, in a north-easterly
direction, but the trend became more easterly as it approached the basin
of the Moray firth. There is a widespread covering of boulder clay,
with scattered groups of moraines, along the ridge extending from
Dores north-east by Culloden moor. There is also a remarkable develop-
ment of fluvio-glacial gravels, high river terraces, and remains of raised
beaches at the mouth of Loch Ness, on both sides of the valley of the
Ness, and on the south shore of the Beauly firth.

Loch Ashie is a shallow lake surrounded by drift, with a fine series
of moraines on its eastern side. Loch Laide also occupies a hollow in
the drift, with small exposures of crystalline schists in places near its
margin. Loch Abban lies in a hollow in the stratified deposits at the
mouth of Loch Ness, which may be of fluviatile origin.

NOTES ON THE BIOLOGY OF THE LOCHS OF THE NESS BASIN.
By JAMES MURRAY.

Collections of plankton were made in twenty-seven lochs in this
basin. With the exception of the lochs in the Great Glen itself, most
of these lochs are at a considerable elevation, occupying the high table-
land on the east of Loch Ness, or the higher mountainous tract on the
west.

The situation of the lochs in two alpine masses, separated by the
deep cleft of the Great Glen, gives rise to some peculiarities in dis-
tribution, most marked in the species of Diaptomus and the more
conspicuous plankton Desmids.

A number of species were only collected on one side of the Great
Glen. These peculiarities are probably due to the fact that the lochs
to the east of Loch Ness were surveyed in spring or early summer, when
the water was still cold, while those to the west were surveyed after
midsummer, when they were about at the maximum temperature.

Difiptomus c/racilis was here, as elsewhere, almost universal, but
was not seen in several of the eastern lochs.

D. laticrp* was in Loch Ness and the other lochs in the Great Glen.
It was not seen in any loch to the west, but was frequent in lochs to the
east of Loch Ness. In Loch Ness the blue Diaptomus (identified by

432 BATHYMETRICAL SURVEY OF

Mr. Scourfield as D. laticeps) is somewhat small and pale in colour.
In other districts, and especially in hill lochs, it is of larger size and
brighter colours — blue or occasionally red. There is some doubt as to
the identity in all cases, and naturalists have given different identifica-
tions of the Loch Ness animal.

D. laciniatus, in contrast to D. laticeps, was only found to the west
of the Glen, in lochs high above the sea. To the east, though it was not
in any of the lochs surveyed, it was in some lochans at a great elevation
on Carnahoulin.

Desmids. — The conspicuous plankton desmids, which constitute
probably the most distinctive feature of the western Scottish plankton
are not very well represented in the lochs of the Ness basin. There are
few species, but they include several of the largest and most beautiful.
They show no marked preference for the one side of the Glen more than
the other, but the greatest number of species is in Loch Aslaich, which
lies west of Loch Ness.

Micrasterias apiculata, var. fimbriata, was in Loch Aslaich, and the
var. bracliyptera was found only once in Loch Ness.

M. radiata, Hass (M. furcata). — This very local species was in Loch
Aslaich.

Staurastrum furciyerum, Breb. — In Loch Bran, at Foyers.

S. longispinum (Bail.). — In Loch Aslaich and several neighbouring
lochs.

S. ophiura, Lund. — Loch Ness and Loch Aslaich.

S. sexangulare (Bulu.). — Loch Garth, near Foyers.

S. brasiliense, Nordst. — Loch Aslaich.

Euastrum verrucosum, Ehr., Micrasterias papillifera, Breb.,
Xanthidium antilopeum (Breb.), Staurastrum gracile, Rolfs, Stauras-
trum lunatum, var. planctonicum, West, and one of the beaked Closteria,
which I identify as C. setaceum, Ehr., are the most generally distributed
desmids in the basin.

Crustacea. — Apart from the Calanidse, a few of the Crustacea appear
to be local in the district.

Sida crystallina. — Only seen in Loch Ness and Loch Aslaich.

Diaphanosoma bracliyurum . — Only noted in the lochs of the Great
Glen and some lochs to the west. The eastern lochs were doubtless
surveyed before its season.

Holopedium gibberum. — Noted in scarcely half the lochs, but those
on both sides of the Glen and at all elevations.

Leptodora was only seen in the lochs of the Glen and Loch Tarff ;
Polyphemus in the Glen and some lochs to the west; Bythotrephes in
the Glen and Lochs Tarff and Ruthven to the east.

Rotifera. — Conochilus unicornis was generally distributed; C. volvox
only in Lochs Ness, Laide, and Knockie.

Floscularia pelagica. — Lochs Ness, Oich/and Uanagan.

THE FRESH -WATER LOCHS OF SCOTLAND. 433

Synchata pectinata. — Lochs Oich and Uanagan.

Anopus testudo. — Lochs Ness and Uanagan.

Triarthra longiseta. — In five lochs on the east side of the basin;
apparently a cold-water species.

Gastropus stylifer. — Loch Ness and five lochs to the east, and Loch
Aslaich to the west.

Surcodina. — ClathruUna was not seen except in the lochs of the
Great Glen. Sebela bicornis, West, though found in Loch Ness, was not
got in the plankton, but while dredging in the shallow water of
Inchnacardoch bay.

Loch J'ess. — Loch Ness was made the subject of a more thorough,
though still far from exhaustive, biological investigation than any other
Scottish loch. A very large proportion of all the lacustrine organisms
known in Scotland have been found in this loch.

The great majority of the species in all the larger groups — Crustacea,
Rot if era, Sarcodina — have been got in Loch Ness, the only large group
not very fully represented being the desmids. Some of the small groups
have hardly been studied, except in Loch Ness, and it is the only loch
the abyssal fauna of which is fairly well known.

To give any detailed account of the hundreds of species found in the
loch would traverse too much the same ground as the general report
on the Biology of the Scottish Lochs. There will therefore be given
here simply an epitome of the biology, and a comparison with the other
lochs in the Ness basin.

The Plankton. — The plankton is the average plankton of Scottish
lakes, with a very small admixture of the more local species. It is very
poor in species, and always very small in quantity. No approach to
" flowering " of the water has been noted. The greatest quantity was
collected in late autumn, 1903, during the night, when a considerable
migration from the deeper water to the surface evidently took place,
as the quantity collected during the preceding day was much less. The
plankton varies little throughout the year, a fact probably correlated
with the low annual range of temperature, which is less than 200-0
Fahr., while the upper limit of about 60°*0 is rarely touched.

About half the species of Crustacea remain all the year round,
those which are absent in winter being Bythotrephes, Polyphemus,
Iseptodora, and Diaphanosoma. Holopedium was noted by Mr. Scour-
field, but was never found during the systematic investigation
afterwards. Diaptomus laticeps, Sars, appears to persist all the year
round, and was found carrying eggs in March, when the temperature
is at its lowest. ClathruUna was generally present, and Volvox
occasionally.

There is a great contrast between Loch Ness and Loch Lochy in the
relative abundance of the phytoplankton. Loch Lochy is very rich,

EE

434 BATHYMETRICAL SURVEY OF

and Loch Ness very poor. The two lochs are only some 10 miles apart,
and are apparently under almost identical conditions. Loch Lochy,
being in an almost uninhabited district, should be purer than Loch
Ness, but a slight pollution is generally favourable to vegetable
growth.

Littoral region. — Though there are only a few sheltered bays in
Loch Ness where littoral vegetation can establish itself, the micro-
fauna and microflora found among the larger vegetation are very
considerable, and constitute, indeed, the chief part of the species in
the loch.

A great many of the animals extend downwards to a very consider-
able depth, and about 40 species (exclusive of Rhizopods), including
many Crustacea, Rotifers, Tardigrada, Worms, and the larvae of many
insects, have been collected as far down as 300 feet. Shells of all the
Rhizopods extend to the greater depth, and many live at greater depths
than 300 feet.

In Inchnacardoch bay Mr. Scourfield found Ophryoxus gracilis for
the first time in Britain; and the rare Ilyocryptus agilis, previously
known in several places in England, was got in the same locality.

Abyssal region. — In Loch Ness a large proportion of the littoral
species extend to about 300 feet in depth, probably because of the very
steeply sloping sides. Those species only are considered as truly abyssal
which are generally distributed over the mud, into the deepest part of
the loch. A small association of animals is found thus distributed,
and the abyssal region, being defined as the bottom where this associa-
tion is found almost free of admixture, must be considered to begin
at about 300 feet. Exclusive of Rhizopods, there are about a dozen
animals constantly found in this region, comprising — 1 Mollusc,
Pisidium pusillum, Gmel. ; 3 Crustacea, Cyclops vir id-is, Jurine,
Candona Candida, Mull., and Cypria opthalmica, Jurine; 3 worms,
Stylodrilus gabretece, Vejd., Automolos morgiensis (Du Plessis), and an
undetermined Oligochsete; 1 insect, Chironomus (larva); several
Infusoria, parasites on the Molluscs and Crustacea.

Several other species occur casually at great depths, such as Hydra,
Limncea, Lynceus affinis, and Proales daphnicola.

A small char, Salmo altinus, was dredged at a depth of over 500
feet.

Larvae of Tanypus and some other diptera are frequent, but less
constant than Chironomus.

Rhizopods. — Dr. Penard has identified about 40 species and varieties
from depths of more than 300 feet. They thus constitute the greater
part of the species in our abyssal region, but their presence there
is of little special interest, and there are only some half a dozen
species and varieties which are doubtfully supposed to be peculiar to
deep lakes.

THE FRESH-WATER LOCHS OF SCOTLAND.

435

Summary of the Number of Species.

Species.
Mollusca ... ... ... ... 5

Hydrachnida ... ... ... 1

Tardigrada 22

Insects

Crustacea

Rotifera

Gastrotricha ...

Worms

Ccelenterata ...

Infusoria

Sarcodina

Mastigophora

6

55

151

2
12

2
11
67

Dinoflagellata

Phanerogamia

Equisetacete ...

Lycopodiaceae

Characese

Mosses

Hepatics

Floridea?

Chlorophyceae

Myxophyceae (Report in prepara

tion)
Bacillariaceae...

Species.
3

. 33
1
1
2

2
2

46

20

We have thus a total of 453 species recorded for Loch Ness, excluding
all Vertebrata, blue-green Algae, and some other groups on which no
work has been done. The Hydrachnida, Insecta, Worms, Infusoria,
Chlorophyceae, and Diatoms have all been insufficiently studied, and
the lists could be easily increased.

PRINTED BY O. CORNWALL AND SONS, ABERDEEN AND LONDON.

VOLUME II

PART II

LOCHS OF THE BRORA BASIN.

WITHIN this basin (see Index Map, Fig. 1), the principal loch is Loch
Brora, which was the only one surveyed. The numerous small hill-lochs
could not be sounded at the time of the visit of the Lake Survey for lack
of boats. The area drained by the river Brora and its tributaries is very
large, extending from the mouth of the Brora, on the east coast of Suther-
land, to the flanks of Ben Armine on the north and of Meall a Fhuarain
on the west, and exceeding 120 square miles, nearly the whole of which
drains into Lech Brora.

Loch Brora (see Plate I.). — Loch Brora is situated about 3 miles from
the shores of the North Sea at Brora, amid beautiful scenery ; the Carrol
Rock overlooking the central part of the loch is very steep, and forms a
fine object. It contains salmon and trout. An island in the southern part
of the loch (Eilean nam Faoileag) was formerly used as a stronghold, and
the ruins of several Pictish towers are to be found in the neighbourhood.
The loch is divided into tkree portions by the alluvium brought down by
the streams, and the Allt Smeoral is rapidly pushing out its alluvium into
the loch to form another barrier. The general trend of the loch is in a
N.N.W. and S.S.E. direction, but the axis is slightly sinuous, so that the
lower portion runs almost north and south, while the upper portion runs
north-west and south-east. Loch Brora is over 3| miles in length, with a
maximum breadth towards the head of the loch of nearly half a mile, the
mean breadth being less than a quarter of a mile. Its waters cover an
area of about 560 acres, or nearly one square mile, and, as already stated,
its drainage area is very large, nearly 140 times the area of the loch.
The maximum depth of 66 feet was observed near the middle of the loch,
about 1-i- miles from the head, and about 2 miles from the foot, of the
loch. The volume of water contained in the loch is estimated at 553
millions of cubic feet, and the mean depth at over 22 J feet. The loch was
surveyed on October 22, 1902, when the elevation of the lake-surface above
the sea was determined by levelling from bench-mark as being 92*9 feet ;
when visited by the officers of the Ordnance Survey on July 25, 1870, the
elevation was found to be 91'3 feet above sea-level. The highest drift-
mark observed on the date of the survey was 7-2 feet above the surface of
the water, and the water may fall about 2 feet below the level on that date,
giving a variation in level exceeding 9 feet.

2 BATHYMETRICAL SURVEY OF

-Loch Brora is extremely irregular in conformation, varying greatly in
width, with corresponding undulations of the lake-floor. There are four
basins, in which the depth exceeds 30 feet. Proceeding from the foot of
the loch the first, smallest, and shallowest basin has a maximum depth of
31 feet. Passing through the first narrows, where a depth of 7 feet was
observed, one enters the second expansion of the loch, which is shallow
until Eilean nam Faoileag is passed, the second basin lying to the north of

English Mites

Bartholomew

FIG. 1. — INDEX MAP OF THE BRORA, HELMSDALE, WICK, WESTER, HEILEN, DUNNET,
THURSO, AND FORSS BASINS.

that island, and having a maximum depth of 43 feet. Passing through the
second narrows, where a depth of 9 feet was found, one enters the third
and deepest basin, enclosing the maximum depth of 66 feet, which was
recorded approximately near the centre of the basin. Passing through the
third and most northerly narrows, in which depths of 4 and 7 feet were
recorded, one enters the fourth and largest basin ; this basin is cut into
two portions by the slight shoaling of the bottom where the alluvial cone

THE FRESH-WATEK LOCHS OF SCOTLAND. 3

laid down by the Allt Smeoral projects into the loch, the deepest water to
the south-east being 59 feet, and to the north-east 64 feet, while on the
shoaling the greatest depth observed was 50 feet. There are two 50-feet
basins : the larger, in the most northerly expansion of the loch, is three-
quarters of a mile in length, and the smaller, in the third expansion from
the foot of the loch, is one-third of a mile in length. The areas between
the contour-lines, and the percentages to the total area of the loch, are
as follows : —

Feet. Acres. Per cent.

Oto25 376 ... 67-2

25 „ 50 130 ... 23-2

over 50 54 9'6

560 100-0

Temperature Observations. — Several readings at the surface on the date
of the survey gave a range of 1°'5 Fahr., from 44°'3 to 45°'8, and a series
taken in the deepest part of the loch at 4-15 p.m., gave the following
results : —

Surface 45c-8 Fahr.

10 feet ! 45°-8 „

20 „ 46°-0 „

45 „ 45°-0 „

65 „ 45°-0 „

This series shows a range of only 1° from surface to bottom, while
lower readings were recorded at the surface than beneath the surface, so
that the body of water was evidently in process of being cooled down from
the summer maximum to the winter minimum.

BATHYMETRICAL SURVEY OF

LOCHS OF THE HELMSDALE BASIN.

THIS large basin extends from the shores of the North Sea at Helmsdale
to the flanks of Ceann Garbh and Cnoc nan Tri-Clach on the north, and of
Creag na h-Iolaire and Ben Armine on the west, the total area being about
220 square miles. The ten lochs within this basin that were sounded by
the Lake Survey Staff, viz., Lochs an Ruathair, Coire nam Meann, Leum
a' Chlamhain, Araich-Lin, Truid air Sgithiche, nan Cuinne, a' Chlair,
Baddanloch, Allt an Fhearna, and na Moine, all lie towards the head-
waters of the basin, while the river Helmsdale, after leaving the lochs,
flows through a large tract of country before reaching the sea, and with its
many tributaries drains the larger portion of the basin. The area draining
into the lochs under consideration is about 82 square miles, as will be
seen from the summary table, while the area draining into the river
Helmsdale irrespective of these lochs is about 138 square miles. In
this respect the Helmsdale basin contrasts strongly with the Brora
basin, where the river Brora, after leaving Loch Brora, drains a very
small area — not more than 3 square miles. The loch nearest the source
of the river Helmsdale is Loch an Ruathair, the stream issuing from
which, on being joined about a mile from the loch by the Knockfin river,
receives the name of Helmsdale. A short distance seawards the river
Helmsdale is joined by the Claggan Burn, bearing the overflow from Lochs
Coire nam Meann, Leum a' Chlamhain, and Araich-Lin, and still a little
farther on it is joined by the Allt Ach' na h-Uai', bearing the overflow
from the remaining lochs in the basin already mentioned.

This series of lochs is interesting on account of the variation in their
outlines, most of them departing from the usual long and narrow form
characteristic of Scottish lochs, while one of them is almost circular in
outline.

Loch an Ruathair (see Plate II.). — Loch an Ruathair (or Loeh-an-
Ruar) is situated close to the Highland Railway line between Kinbrace
and Forsinard stations. It is a good fishing loch, containing trout and
char, amid pretty surroundings, with Creag Sail a' Blathaich (1139 feet),
and Meall a' Bluirich (1331 feet), rising off the north-western shore,
overshadowed by the peaks of Ben Griam Mhor and Ben Griani Bheag,
which attain an elevation of nearly 2000 feet, farther distant in the same
direction, while to the south-east the Knockfin heights exceed 1400 feet.

THE FRESH-WATER LOCHS OF SCOTLAND. 5

The trend of the loch is almost north and south, the outline being some-
what oblong. The loch exceeds 1 J miles in length, with a maximum breadth
of over three-quarters of a mile, the mean breadth being over half a mile.
It is thus a very wide loch in relation to the length, the greatest width being
one-half, and the average width one-third, of the length. Its waters cover
an area of about 523 acres (over three-quarters of a square mile), and it
drains an area fourteen times greater, an area of 11^ square miles. Seventy
soundings were taken, the maximum depth of 26 feet being observed
towards the southern end and nearer the western shore. The volume of
water contained in the loch is estimated at 304 million cubic feet, and the
mean depth at 13^ feet, or one-half of the maximum depth. The loch was
surveyed on October 3, 1902, when the elevation of the lake-surface was
found to be 414-8 feet above the sea ; when levelled by the officers of the
Ordnance Survey on July 28, 1869, the elevation was nearly identical :
414*5 feet above sea-level.

Loch an Ruathair is a comparatively shallow and flat-bottomed basin.
The 1 0-feet contour-line coincides" approximately with the outline of the
loch, but the area enclosed by the 20-feet contour is peculiar in form,
consisting of a main body situated in the southern portion of the loch,
sending out two prolongations in a northerly direction. These prolonga-
tions approach the eastern and western shores respectively, while the
central parts in the northern half of the loch are occupied by slightly
shallower water. The deepest sounding of 26 feet was taken in the centre
of the main body of deep water above referred to, about one-third of a
mile from the southern end of the loch. The slope of the bottom is
moderately steep off the western shore near the southern end, where
soundings of 10 and 12 feet were recorded about 100 feet off-shore, but
elsewhere the soundings indicate a very gentle slope. The flat-bottomed
character of the loch as a whole is shown by the following table, giving
the areas between the contour-lines, and the percentages to the total
area : —

Feet. Acres. Per cent.

OtolO 169 ... 32

10 „ 20 251 ... 48

over 20 '. 103 ... 20

523 100

A series of temperatures taken in the afternoon of October 3, 1902,
gave identical readings at the surface, at 10 feet, and at 18 feet, viz.
53°-0 Fahr.

Loch Coire nam Meann (see Plate II.). — Loch Coire nam Meann (or
Coire nam Mang) lies about 4 miles to the north-west of Loch an
Ruathair, at the foot of Ben Griam Mhor. It is a good fishing loch,
the trout being very large, but is preserved. This loch is nearly circular
in outline, with a maximum diameter of over half a mile, covering an area

6 BATHYMETRICAL SURVEY OF

of about 120 acres, and receiving the drainage from an area of three
quarters of a square mile. Its superfluent water is carried by a short
stream into the neighbouring Loch Leum a' Chlamhain, lying less than
a quarter of a mile to the east. The maximum depth of 33 feet was
observed comparatively close to the south-eastern shore. The volume
of water is estimated at 60 million cubic feet, and the mean depth at
11 J feet. The loch was surveyed on October 20, 1902, but the elevation
above the sea could not be determined; when visited by the officers of
the Ordnance Survey on June 10, 1870, the elevation was found to be
800*5 feet above sea-level.

Loch Coire nam Meann forms a simple basin, but the north-western
portion is comparatively shallow, the deeper water occurring in the south-
eastern portion, the deepest sounding having been recorded less than 200
yards from that shore. The deep water, however, is of limited extent, for
only 15 per cent, of the lake-floor is covered by more than 20 feet of
water, while about one half of the lake-bottom is covered by less than 10
feet of water, as shown in the following table : —

Feet. Acres. Per ceiit.

OtolO 58 ... 49

10 „ 20 43 ... 36

over 20 18 15

119 100

The temperature of the surface water at 3 p.m. on October 20, 1902,
was 45°'0 Fahr.

Loch Leum a' Chlamhain (see Plate II.). — Loch Leum a' Chlamhain (or
(Leum-na-Clavan, or Leum-a-Chamblain) is a fine fishing loch, like its
neighbour Loch Coire nam Meann, famous for the large size of its trout
and for the heavy baskets frequently recorded; like its neighbour also
it is strictly preserved. Ben Griam Mhor lies to the south, and Ben
Griam Bheag to the east. The outflowing water is carried by the Allt
Airidh-dhamh into Loch Araich-Lin. The loch trends nearly north and
south, and is If miles in length. It varies greatly in width, with a
constriction in the central part, the maximum breadth exceeding half a
mile towards the northern end of the loch, the mean breadth being one-
third of a mile. Its waters cover an area of about 350 acres, or over half
a square mile, and it drains directly an area of nearly four square miles,
but since it receives the outflow from Loch Coire nam Meann its total
drainage area is about 4f square miles. The maximum depth of 51 feet
was observed near the southern end of the loch, while towards the
northern end a depth of 50 feet was recorded. The volume of water
is estimated at 298 million cubic feet, and the mean depth at 19^ feet.
The loch was surveyed on October 20, 1902, but the elevation above the
sea could not be determined ; when levelled by the Ordnance Survey

THE FRESH-WATER LOCHS OF SCOTLAND. 7

officers on June 10, 1870, the elevation of the lake-surface was found to
be 770*0 feet above sea-level.

Loch Leum a' Chlamhain consists of two deep basins placed respectively
towards the two ends of the loch, separated by shallower water near the
central part of the loch. The separation does not, however, coincide with
the narrowest part of the loch, in which a depth of 30 feet was found, but
occurs farther to the south, where the greatest depth recorded was 24 feet.
The 10-feet and 20-feet contour-lines enclose continuous areas, but the
deeper contours enclose the two deep basins referred to. The smaller
but deeper basin lies near the southern end of the loch, the deepest
sounding of 51 feet having been recorded about 350 yards from the
southern shore, while the larger basin lies towards the northern end, the
greatest depth therein (50 feet) having been recorded about 600 yards
from the northern shore. The areas between the consecutive contour-
lines, and the percentages to the total area of the loch, are as follows : —

Feet. Acres. Per cent.

Oto25 254 ... 72-7

25 „ 50 90 ... 25-7

over 50 6 ... 1-6

350 100-0

Temperature observations on the date of the survey gave identical
readings of 46°'0 Fahr. at the surface, at 10 feet, at 20 feet, and at 40 feet.

Loch Araicli-Lin (see Plate II.). — Loch Araich-Lin (or Arichlinie or
Ari-cliny) is situated about three-quarters of a mile to the south-west of
Loch an Euathair, and about 3j miles to the south-east of Loch Leum a'
Chlamhain. It contains trout and char, but the fishing is preserved. It is
a shallow lake, trending nearly north and south, and three-quarters of a
mile in length by one-third of a mile in maximum breadth, while the mean
breadth is a quarter of a mile. Its waters cover an area of about 117
acres, and it drains directly an area exceeding 10 square miles, but since it
receives the outflow from Lochs Leum a' Chlamhain and Coire nam Meann,
its total drainage area is about 15 square miles — an area eighty times
greater than that of the loch. The maximum depth of 7 feet was observed
in several places in the southern portion of the loch and along the eastern
shore. The volume of water is estimated at 23 million cubic feet, and the
mean depth at 4| feet. The loch was surveyed on October 3, 1902, when
the elevation of the lake-surface was found by levelling from bench-mark
to be 451-8 feet above the sea; when visited by the Ordnance Survey
officers on July 27, 1869, the elevation was 451-4 feet above sea-level. The
highest drift-mark observed on the date of the survey was about 3j feet
above the surface of the water, and the local boatman stated that the
water might fall about H feet, giving a range in level of about 5 feet.

Loch Araich-Lin is a shallow flat-bottomed basin, apparently in pro-
of being silted up. Along the western shore the water is shallower

8 BATHYMETRICAL SURVEY OF

than along the opposite shore, and at the mouths of the inflowing streams
banks of alluvium are being laid down. The majority of the soundings
gave depths of 5, 6, and 7 feet, the area of the lake-floor covered by more
than 5 feet of water being about 65 acres, or 56 per cent, of the total area
of the loch. The temperature of the surface water at 11.30 a.m. on
October 3, 1902, was 50°-8 Fahr.

Loch Truid air Sgithiche (see Plate II.). — Loch Truid air Sgithiche
(or Truderscaig) lies at the base of Ben Armine, amid beautiful surround-
ings, about 9 miles from Kinbrace station, on the Highland Kailway. It
is a splendid trout loch, but the fishing is preserved. In outline it is
triangular, with the apex pointing in a north-east direction. The out-
flowing stream, the Allt an Loin Tharsuinn leaves the loch at the apex
of the triangle, and flows into Loch nan Cuinne lying about a mile to the
north-east. Loch Truid air Sgithiche is nearly a mile in length, with
a maximum width of nearly two-thirds of a mile, the mean breadth being
one- third of a mile. Its waters cover an area of about 186 acres, and
it drains an area of about 8 square miles. The maximum depth of 12 feet
was observed about halfway down the loch, but towards the eastern shore.
The volume of water is estimated at 47 million cubic feet, and the mean
depth at rather less than 6 feet. The loch was surveyed on October 18,
1902, but the elevation above the sea could not be determined ; when levelled
by the officers of the Ordnance Survey on August 23, 1870, the elevation
of the lake-surface was 425*9 feet above sea-level. The boatman stated
that the water might rise about a foot above, and fall a foot below, the
level on the date of the survey.

Loch Truid air Sgithiche is on the whole shallow and flat-bottomed,
with weeds growing in the Western angle of the loch. Only four of the
soundings gave depths exceeding 10 feet, and these lie towards the eastern
shore, the deepest sounding in 12 feet having being recorded about 200 yards
from that shore. The majority of the soundings were taken in depths
between 5 and 10 feet, as is borne out by the following table showing
the areas between the contour-lines and the percentages to the total area
of the loch : —

Feet. Acres. Per cent.

Oto5 72 ... 38-5

5 ,,|10 101 ... 54-3

over 10 13 7-2

186 ... 100-0

The temperature of the surface water at 1 p.m. on October 18, 1902, was
44°-5 Fahr.

Loch nan Cuinne (see Plate II.). — Loch nan Cuinne (or nan Cuidhean,
or na-Cuin, known locally as Bimsdale Loch) is closely connected with
Loch a' Chlair and Loch Baddanloch, the outflow from Loch nan Cuinne

THE FRESH- WATER LOCHS OF SCOTLAND. 9

being carried into Loch a' Chlair by a stream, Uidh Bheag, less than
100 yards in length, the difference in the level of the two lochs being only
half a foot. It is a good trout loch, but the fishing is preserved. The
island shown on the Ordnance Survey map in the central part of the loch,
near the southern end, was indicated by only a few reeds at the time of the
survey. Loch nan Cuinne is a large but comparatively shallow loch, trend-
ing north and south, and 3 miles in length. It varies greatly in width, the
northern portion being very narrow, while in the central portion at the out-
flow the loch widens out and attains a maximum breadth exceeding three-
quarters of a mile ; the mean breadth is over one-third of a mile. Its
waters cover an area of about 734 acres, or considerably more than 1 square
mile, and it drains directly an area of over 22 square miles, but since
it receives the outflow from Loch Truid air Sgithiche, its total drainage
area exceeds 30 square miles. The maximum depth of 28 feet was ob-
served in the wide central part of the loch, but nearer the eastern than the
western shore. The volume of water is estimated at 396 million cubic
feet, and the mean depth at nearly 12^ feet. The loch was surveyed
on October 18, 1902, when the elevation of the lake-surface was found to
be 395*0 feet above the sea, and 6 inches higher than Lochs a' Chlair and
Baddanloch.

Loch nan Cuinne is simple in conformation. The 10-feet area is con-
tinuous from end to end, though the contour-line is here and there of a
sinuous character, with a shallow patch round the island near the southern
end, while the 20-feet area occupies the wide central portion of the loch,
and is nearly a mile in length. The deepest sounding in 28 feet was taken
about 300 yards from the eastern shore. The areas between the contour-
lines, and the percentages to the total area of the loch, are as follows :—

Feet. Acres. Per cent.

OtolO 299 ... 40-7

10 „ 20 317 ... 43-2

over 20 118 ... 16-1

734 100-0

Temperature observations taken at 3 p.m. on the date of the survey
gave 46" -5 Fahr. at the surface and at a depth of 10 feet, while a reading
at 20 feet gave 47°-0.

Loch a' Chlair (see Plate II.).— Loch a' Chlair (or nan Clar) is
continuous with Loch Baddanloch, the passage between them being about
200 yards across and having a depth of 5 feet. The entire sheet of water
trends in a north-west and south-east direction, and is 3^ miles in length,
covering an area exceeding 2 square miles. The fishing, both trout and
char, is preserved, and the surroundings very fine, several lofty peaks being
visible, including Morven to the south-east, Ben Griam to the north-east,
Ben Armine and Ben Klibreck to the south-west, Ben Hee to the west, and
Ben Hope and Ben Loyal to the north-west. Loch a' Chlair is somewhat

1.0 BATHYMETKICAL SUKVEY OF

crescent-shaped, with the concave side to the south ; the length from east
to west exceeds 1J miles, the maximum width in a north and south
direction being 1| miles, while the mean breadth is over three-quarters
of a mile. Its waters cover an area of about 750 acres (or considerably
over 1 square mile), and it drains directly an area of 13 square miles, but,
since it receives the outflow from Lochs nan Cuinne and Truid air Sgit-
hiche, its total drainage area is about 43^ square miles — an area 37 times
greater than that of the loch. The maximum depth of 32 feet was
observed approximately midway between the eastern and western shores,
but much nearer the southern than the northern shore. The volume
of water is estimated at 446 million cubic feet, and the mean depth at over
13J feet. The loch was surveyed on October 17, 1902, when the level
of the surface water was found to be 394-5 feet above the sea ; when visited
by the Ordnance Surveyors on July 22, 1869, the elevation of the lake-
surface was 392-2 feet above sea-level.

Loch a' Chlair forms a simple basin; the 10-feet contour-line coincides
approximately with the outline of the loch, but the deeper contours
approach more nearly to the southern shore, the deepest sounding in
32 feet having been taken about 350 yards from that shore. The area of
the lake-floor covered by less than 10 feet of water is about 265 acres,
or 35 per cent, of the total area of the loch, while the area covered by
more than 25 feet of water is about 38 acres, or 5 per cent. The
temperature of the surface water on the date of the survey was 47 °- 2 Fahr.,
while readings at 10 feet and at 25 feet gave 47°*0.

Loch Baddanloch (see Plate II.). — Loch Baddanloch (or Badenloch,
or Baden) is nearly 1| miles in length from north-west to south-east,
having a maximum width at the northern end of nearly a mile, narrowing
gradually towards the opposite end, the mean breadth exceeding half a
mile. Its waters cover an area of about 634 acres, or 1 square mile, and
it drains directly an area of 6 square miles, but since it receives the out-
flow from Lochs Truid air Sgithiche, nan Cuinne, and a' Chlair, as well as
from Loch Allt an Fhearna, next to be considered, its total drainage area
is over 51| square miles. The maximum depth of 42 feet was observed
about halfway down the loch, but rather nearer the south-western than the
north-eastern shore. The volume of water is estimated at 479 million
cubic feet, and the mean depth at 17| feet. The loch was surveyed on
October 15, 1902 ; the elevation is, of course, identical with that of Loch
a Chlair. It may be noted that in the interval of two days between the
surveys of the two lochs, the water rose to the extent of 2 feet, but the
soundings laid down on the maps have been referred to the same datum
level.

Loch Baddanloch is simple in conformation, with few minor undulations
of the lake-floor. The 10-feet contour agrees with the course of the shore-
line, and the deeper contours are approximately centrally placed. The

THE FRESH-WATER LOCHS OF SCOTLAND. 11

deepest sounding in 42 feet was taken about 400 yards from the south-
western shore. The area covered by less than 10 feet of water is about
154 acres, or 24 per cent, of the total area of the loch, while the area
covered by more than 25 feet of water is about 113 acres, or 18 per cent.
Temperature observations on the date of the survey gave identical readings
at the surface, at 10 feet, and at 25 feet, viz. 48°'0 Fahr.

Loch Allt an Fhearna (see Plate II.). — Loch Allt an Fhearna (or Loch
an Alltain Fhearna, or Loch Alt-an-Fearn) lies about half a mile to the
west of Loch Baddanloch, into which it flows by the Uidh a' Chlarain. It
is pear-shaped, narrowing from the south-east towards the north-west, and
is nearly a mile in length, with a maximum width of over half a mile, the
mean breadth exceeding one-third of a mile. Its waters cover an area of
about 212 acres, or one-third of a square mile, and it drains an area of
2 square miles. The maximum depth of 36 feet was observed approxi-
mately in the centre of the wide part of the loch, that is to say, nearer
the south-eastern than the north-western end. The volume of water is
estimated at 132 million cubic feet, and the mean depth at 14J feet. The
loch was surveyed on October 18, 1902, but the elevation of the lake-
surface could not be determined ; when visited by the officers of the
Ordnance Survey on December 3, 1870, the elevation of the lake-surface
was found to be 43 2' 6 feet above the sea. A drift-mark was observed
1 foot above the water on the date of the survey.

Loch Allt an Fhearna is quite simple in conformation, the bottom
sloping down on all sides towards the deepest part, which lies in the
south-eastern part of the loch, the deepest sounding in 36 feet having been
taken about 450 yards from the south-eastern shore. The slope of the
bottom is on the whole steeper off shore than in the deeper water, as is
shown in the following table giving the areas between the consecutive
contour-lines, and the percentages to the total area of the loch : —

Feet. Acres. Percent.

OtolO 68 ... 32

10 „ 20 99 ... 47

20 „ 30 34 ... 16

0%-er 30 11 ... • 5

212 100

Temperature observations taken in the deepest part of the loch at
2.30 p.m. on October 18, 1902, gave identical readings at the surface, at
17 feet, and at 34 feet, viz. 46°-0 Fahr.

Loch na Moine (see Plate II.). — Loch na Moine (or Achnamoine) lies
about 2\ miles from Kinbrace station on the Highland Railway, and about
1J miles to the south-east of Loch Baddanloch, the overflow from which is
carried into it by the An Ei' Mhor. It is a small shallow loch, remarkable

12

BATHYMETKICAL SURVEY OF

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THE FRESH- WATER LOCHS OF SCOTLAND. 13

on account of the large area draining into it — an area 400 times greater
than that of the loch. The fishing includes both salmon and trout, but is
preserved. The loch trends in a west-north-west and east-south-east
direction, and is nearly a mile in length, with a maximum breadth of
a quarter of a mile. Its waters cover an area of about 88 acres, and
it drains directly an area of about 4J square miles, but since it receives the
overflow from Lochs Baddanloch, Allt an Fhearna, a' Chlair, nan Cuinne,
and Trnid air Sgithiche, its total drainage area exceeds 55f square miles.
The maximum depth of 8 feet was observed approximately in the centre of
the loch. The volume of water is estimated at 18 million cubic feet, and
the mean depth at over 4J feet. The loch was surveyed on October 14,
15»02, but the elevation of the lake -surface could not be determined; when
levelled by the Ordnance Survey officers on July 19, 1869, the elevation
was found to be 3 7 6- 6 feet above the level of the sea. Loch na Moine is
quite simple in conformation, the water deepening gradually on all sides
towards the centre, with weeds growing along the south-western shore and
many stones in the narrow portion at the south-eastern (outflow) end.
The flat-bottomed character of the basin is shown by the fact that an area of
about 46£ acres, or 53 per cent, of the total area of the loch, is covered by
more than 5 feet of water.

Temperatures taken at 1 p.m. on the date of the survey gave identical
readings (480>0 Fahr.) at the surface and at a depth of 6 feet.

In the eleven lochs in the Brora and Helmsdale basins, as shown
in the opposite table, 700 soundings were taken, and the aggregate area
of the water-surface is 6*69 square miles, so that the average number of
soundings per square -mile of surface is 104.

The aggregate volume of water contained in the lochs is estimated at
2756 millions of cubic feet. The area drained by these lochs is about
203 square miles, or over thirty times the area of the lochs.

14 BATHYMETKICAL SURVEY OF

LOCHS OF THE WICK BASIN.

THERE are three lochs within this basin which were sounded by the Lake
Survey, viz. Lochs Scarmclate, Watten, and Hempriggs ; there were no
boats on the few smaller lochs, of which the most important are the Loch
of Toftingall, lying to the south-west of Loch Watten, and the Loch of
Yarehouse, lying to the south-west of Loch Hempriggs. The basin is a
fairly large one, extending from Wick bay on the east coast of Caithness
to Sordal hill on the north-west, and to Stemster hill on the south-west,
the larger portion being drained by the Wick water and its tributaries
independently of the lochs under consideration. The outflow from Loch
Scarmclate is carried by the Quoynee burn into Loch Watten, thence into
the sea at Wick by the Wick water, which is joined a short distance from
the head of Wick bay by the burn of Newton, bearing the outflow from
Loch Hempriggs. The lochs are characterized by their shallowness,
although one of them (Loch Watten) covers a larger superficial area
than any other of the Caithness lochs ; they contain trout, but the fishing
is preserved.

Loch Scarmclate (see Plate III.). — Loch Scarmclate (or Scarmclett, or
Stemster) is situated about 7 miles to the south-east of Thurso, and over
a mile to the north-west of Loch Watten, surrounded by cultivated land,
the margins of the loch being swampy and reedy. The loch is somewhat
triangular in outline, with the apex pointing to the south-east, and nearly
a mile in length, with a maximum breadth exceeding half a mile. The
superficial area is about 1 90 acres, or less than one-third of a square mile,
and the drainage area about 7 square miles. The floor of the loch is
practically uniform in depth, about one-half of the soundings being taken
in 5 feet of water, which was the maximum depth observed. The volume
of water is estimated at 21 million cubic feet, and the mean depth at half
the maximum depth. The loch was surveyed on October 7, 1902, and
the elevation of the lake-surface above the sea was determined as being
89 '5 feet, which is half a foot higher than the elevation determined by
the officers of the Ordnance Survey on February 28, 1871, viz. 89-1 feet.
The water in the loch was high on the date of the survey, and a drift-
mark was observed about a foot above the surface of the water, but the
range in level is apparently very small. The deposits covering the lake-
floor are brown muds, except over a small area to the south of the island,

THE FRESH-WATER LOCHS OF SCOTLAND. 15

where the deposit is white and calcareous, and it was a regular practice
some few years ago to dredge the loch to the south of the island, and
to use the mud for marling the land.

Loch Watten (see Plate III.).— Loch Watten, the largest of the Caith-
ness lochs, is situated about midway between Wick and Thurso, the
railway between those places running along its northern shore, and the
main road skirting its southern shore. » The loch trends in a north-west
and south-east direction, with a slight sinuosity in the outline, the upper
portion being narrower than the main body of the loch, and bending in a
northerly direction. It is 3 miles in length, with a maximum breadth
towards the lower end of three-quarters of a mile, the mean breadth being
about half a mile. Its waters cover an area of about 930 acres, or about
H square miles, and it drains directly an area of over 13 square miles, but
since it receives the overflow from Loch Scarmclate its total drainage area
is about 20J square miles. The maximum depth observed was 12 feet,
and no fewer than thirty-six soundings were taken at this depth in the
south-eastern half of the loch. The volume of water is estimated at 341
million cubic feet, and the mean depth at 8J feet. The loch was surveyed
on October 8 and y, 1902, when the elevation of the lake-surface was
found to be 54*9 feet above the sea ; when levelled by the officers of the
Ordnance Survey on December 28, 1869, the elevation was 55'4 feet above
sea-level. According to the miller at Watten, the wind sometimes per-
ceptibly affected the level of the water, and after an easterly wind had
been blowing strongly for some time it was impossible for him to work
the mill, the water being driven before the wind and piled up at the
north-west end. The water might rise 2 feet above, and fall 1 foot
below, the level on the date of the survey.

Loch Watten may be described as a large, shallow, flat-bottomed
basin, the deeper portion lying towards the south-eastern end, the water
shoaling more gradually on proceeding towards the north-western end.
The great majority of the soundings were taken in depths exceeding
5 feet, and more than one half of the lake-floor is covered by more than
10 feet of water. The mean depth of the entire basin is 70 per cent, of
the maximum depth. The temperature of the surface water at 10 a.m. on
October 8, 1902, was 49°'9 Fahr., and at 10 a.m. on October 9, the surface
temperature was 490<6, while a reading at 12 feet gave 49°'o.

Loch Hempriggs (see Plate III.). — Loch Hempriggs lies about 2 miles
to the south-west of the town of Wick, and within a mile of the shores of
the North Sea, though the outflowing stream pursues a long and devious
course in a northerly direction before joining the Wick water on its way
to the sea. The loch is irregularly subcircular in outline, and the
maximum diameter from north to south and from east to west is in
each case about three-quarters of a mile. The superficial area is about

16 BATHYMETRICAL SURVEY OF

217 acres, or one-third of a square mile, and the drainage area is nearly
9J square miles. The maximum depth of 8 feet was recorded at six
soundings in the northern half of the loch. The volume of water is
estimated at 49 million cubic feet, and the mean depth at f>J feet. The
loch was surveyed on October 10, 1902, when the elevation of the lake-
surface was found by levelling from bench-mark to be 153' 7 feet above
the sea; when visited by the Ordnance Survey officers on February 18,
1870, the elevation was 155-5 feet above sea-level. The height of the
water is regulated by a sluice, and the cracked peaty soil at the margin,
with boulders covered by a luxuriant growth of Fontinalis, indicated a
very recent fall of about 2 feet from a former long-maintained level.

Like the other lochs in this locality, Loch Hempriggs is a shallow,
flat-bottomed basin, over two-thirds of the lake-floor being covered by
more than 5 feet of water, and the mean depth of the entire loch is about
65 per cent, of the maximum depth. The temperature of the surface
water on the date of the survey was 480<9 Fahr., while readings at depths
of 3 feet and 7 feet gave in each case 48°'5.

THE FRESH-WATER LOCHS OF SCOTLAND. 17

LOCHS WESTER, HEILEN, AND ST. JOHN'S.

THESE three lochs apparently drain into the sea by separate streams.
An inspection of the Ordnance Survey maps on the 6-inch and 1-inch scales
would lead one to suppose that the outflow from Loch Heilen was carried
into the Loch of Wester by the Burn of Eeaster and the Burn of Lyth,
but Mr. Garrett, who assisted in the survey, states that Loch Heilen drains
out to the north, so that the draining stream is the Burn of Inkstack,
which in its northward course passes close to St. John's Loch.

Loch of Wester (see Plate IV.). — The Loch of Wester lies little more
than half a mile from the sea at Sinclair's Bay, Moray Firth, and only 6
feet above sea-level. The water of Wester carrying the outflow from the
loch is about a mile in length, and when the tide is out there is no per-
ceptible current in the river. Ordinary spring tides flow as far as Bridge
of Wester, less than a quarter of a mile from the loch, while high spring
tides are said to carry seaweed right up to the head of the loch, and to
make the water salt for a time ; a recent tidal drift-mark was observed 2
feet above the level of the water on the date of the survey. The loch
contains sea-trout and loch-trout, but the fishing is preserved. The trend
of the loch is north-west and south-east, and the length 1 mile, while the
superficial area is about 110 acres, and the drainage area comparatively
large, about 29^ square miles. The loch is extremely shallow, the maxi-
mum depth of 3 feet occurring in various places throughout the loch ; the
river between the loch and Bridge of Wester was found to be deeper than
anything observed in the loch. The Loch of Wester was surveyed on
October 11, 1902, when the temperature of the surface water was 44D-3
Fahr. ; a reading at 3 feet gave 44r-l.

Loch Heilen (see Plate V.). — Loch Heilen (or Loch of Hailan) is a
small shallow loch lying in cultivated land, surrounded by reeds, about
2 miles to the east of Dunnet Bay on the north coast of Scotland,
and about 8 miles from Thurso. Duck and other wild fowl are very
abundant. The loch trends in an east and west direction, and is somewhat
crescent-shaped in outline. The length is over H miles, and the maximum
breadth nearly half a mile, the superficial area being about 191 acres, or
nearly one-third of a square mile. Several soundings in 5 feet of water
(the maximum depth observed) were taken in the central part of the loch.

c

18 BATHYMETEICAL SURVEY OF

The volume of water is estimated at 21 million cubic feet, and the mean
depth at one-half the maximum depth. The loch was surveyed on
October 11, 1902, when the elevation of the lake-surface was found to be
112*8 feet above the sea, which is almost identical with the elevation
determined by the officers of the Ordnance Survey on December 12, 1870,
viz. 112-9 feet above sea-level. The surface temperature on the date of the
survey was 46° -0 Fahr.

St. John's Loch (see Plate V.).— St. John's Loch lies a little over half
a mile to the north-east of Dunnet Bay, into which its overflow is carried
by the Burn of Dunnet. It is a small shallow loch ; the western end is
stony, and here many shells of lamellibranchs and gasteropods were
found on the shore, having been thrown up by the wind. The loch is
subcircular in outline, with a maximum diameter from east to west of less
than a mile, the maximum breadth from north to south exceeding half
a mile, its waters covering an area of about 195 acres, or nearly one-
third of a square mile. The maximum depth of 7 feet was observed in the
south-eastern part of the loch. The volume of water is estimated at 38
million cubic feet, and the mean depth at 4| feet. The loch was surveyed
on October 10, 1902, when the elevation of the lake-surface was found to
be 71 '3 feet above the sea ; when levelled by the officers of the Ordnance
Survey on February 4, 1871, the elevation was 72-1 feet above sea-level.
The highest drift-mark observed was a foot above the level of the water on
the date of the survey, and it was stated that the water might fall to the
extent of 1| feet.

St. John's Loch is a shallow flat-bottomed basin, the deep water
occupying the eastern half of the loch, the deepest cast in 7 feet having
been taken about 100 yards from the southern shore and less than 400
yards from the eastern end. The area of the lake-floor covered by more
than 5 feet of water is about 114 acres, or 58 per cent, of the total area.
The temperature of the surface water on the date of the survey was 46°'4
Fahr.

THE FRESH-WATER LOCHS OF SCOTLAND. 19

LOCHS OF THE THUKSO BASIN.

TOWARDS the headwaters of the river Thurso there are several small
lochs, the most important being Loch More, which was the only one
sounded by the Lake Survey. This loch, which must not be confounded
with the larger Loch More in Sutherlandshire, is famous for its salmon
and trout fishing ; the large area of country draining into it is a striking
characteristic.

Loch More (see Plate VI. j. — Loch More lies about 13 miles to the
south of Thurso, the overflow from the loch being carried by the river
Thurso, after a long and devious course, into Thurso bay. The loch is
irregularly subcircular in outline, with a maximum diameter in a north
and south direction of less than a mile, the mean breadth being one-third
of a mile. The superficial area is about 177 acres, or a quarter of a square
mile, and the area draining into it is about 67^ square miles — an area
24< > times greater than that of the loch. The maximum depth of 7 feet
was observed near the eastern shore, off the mouth of the outflowing river.
The volume of water is estimated at 32 million cubic feet, and the mean
depth at 4 feet. The loch was surveyed on October 9, 1902, when the
elevation of the lake-surface above the sea was found by levelling from
bench-mark to be 381 '4 feet ; when levelled by the officers of the Ordnance
Survey in July, 1870, the elevation was 381*0 feet above sea-level.

Like most of the Caithness lochs, Loch More is a shallow, flat-bottomed
basin. Most of the soundings were taken in depths of 5 and 6 feet ; the
deepest cast in 7 feet was taken about 100 yards from the eastern shore
where the river Thurso flows out, while along the southern and northern
shores the bottom is being silted up by the deposition of material laid
down by the Strathmore water and the Sleach water. The area of the
lake- floor covered by less than 5 feet of water is about 92 acres, or 52
per cent, of the total area of the loch. On the date of the survey, tem-
perature observations gave 46°'0 Fahr. at the surface and at a depth of
3 feet, while a reading at 6 feet gave 45 :- 8.

20 BATHYMETRICAL SURVEY OF

LOCHS OF THE FORSS BASIN.

THE Lake Survey staff sounded the two principal lochs within this basin,
viz. Lochs Calder and Shurrery. The few smaller lochs — of which the
most important are Loch Olginey flowing into Loch Calder, and Loch
Chaluim flowing into Loch Shurrery — could not be surveyed for lack of
boats. The headwaters of the basin take their rise on the flanks of Beinn
nam Bad Mhor and Cnoc an Fhuarain Bhain, flowing by the Cnocglass
or Torran water into Loch Shurrery, from which issues the Forss water,
which on its way to the sea is joined by the Alltan Glminne, bearing the
overflow from Loch Calder. Like most of the Caithness lochs, Loch
Shurrery is shallow, while Loch Calder is important both on account of
its depth, and because it is the source of the water-supply to the town of
Thurso. The fishing in both lochs is good, though preserved ; salmon and
trout being got in Loch Shurrery, and trout and char in Loch Calder.

Loch Shurrery (see Plate VII.). — Loch Shurrery lies about 8 miles
from Thurso and 7 miles from Reay, on the north coast of Caithness.
The loch trends in a north and south direction, and is 1£ miles in length,
the maximum width being less than half a mile. Its waters cover an area
of about 228 acres, or over one- third of a square mile, and it drains an
area of 29 square miles. The maximum depth of 7 feet was observed in
two places — near the middle of the loch towards the eastern shore, and
near the foot of the loch towards the western shore. The volume of water
is estimated at 43 million cubic feet, and the mean depth at 4J feet. The
loch was surveyed on October 6, 1902, when the elevation of the lake-
surface was found to be 321*45 feet above the sea ; when levelled by the
Ordnance Survey officers on June 4, 1870, the elevation was 321'1 feet
above sea-level. Loch Shurrery is a shallow, flat-bottomed basin, the
majority of the soundings having been taken in depths of 5 and 6 feet,
while three soundings were taken at the maximum depth of 7 feet — two
near the centre and one near the northern end, as already indicated. The
area of the lake-floor covered by more than 5 feet of water is about 121
acres, or 53 per cent, of the total area of the loch. The temperature of
the surface water towards the southern end was 50°*0 Fahr., while towards
the northern end readings at the surface and at a depth of 3 feet gave
49°'5, and a reading at 5 feet gave 49°-2.

THE FRESH- WATER LOCHS OF SCOTLAND. 21

Loch Calder (see Plate VII.). — Loch Calder lies about 5 miles to the
south-west of Thurso. It is a large loch, distinguished from the other
Caithness lochs visited by the Lake Survey by its great depth. At the
time of the survey green algae abounded in the water, and gulls and other
birds were very numerous. The loch trends in a north-west and south-
east direction, and is 2^ miles in length. The southern portion is narrow
and shallow, while the northern portion is much wider and deeper, the
maximum breadth being very nearly 1 mile, and the mean breadth of the
entire loch exceeding half a mile. The superficial area is about 844 acres,
or 1J square miles, and the drainage area nearly 10 square miles. The
maximum depth of 85 feet was observed towards the northern end and
towards the eastern shore. The volume of water is estimated at 767
millions of cubic feet, and the mean depth at nearly 21 feet. The loch
was surveyed on October 6, 1902, but the elevation of the lake-surface
above the sea could not be determined ; when levelled by the officers of
the Ordnance Survey on May 28, 1870, the elevation was found to be
205-2 feet above sea-level. It was stated that the water might rise 2 feet
above, and fall about 1 J feet below, the level on the date of the survey ;
but the level is affected by a sluice at Achavarn, which is used both by
South Calder mill and by the Thurso waterworks.

Loch Calder is irregular in outline, and rather peculiar in conforma-
tion. In the wide portion of the loch, off the western shore, there is an
island situated on a large bank surrounded by deeper water, and the
narrow southern portion is so shallow that one must proceed three-quarters
of a mile from the southern end before meeting with depths exceeding
11 feet. The deep basin is contained in the eastern half of the wide
northern portion of the loch, the deepest sounding in 85 feet having been
taken about half a mile from the northern shore and a quarter of a mile
from the eastern shore. Here there is a basin about a mile in length, and
exceeding 30 feet in depth, the 50-feet basin being nearly three-quarters
of a mile in length, and distant about a quarter of a mile from the northern
shore. The loch, as a whole, is comparatively shallow, since 72 per cent,
of the lake-floor is covered by less than 25 feet of water, as will be
seen from the following table, giving the approximate areas between the
consecutive contour-lines, and the percentages to the total area of the
loch :—

Feet. .Acres. Percent.

Oto25 606 ... 71-8

25 „ 50 170 ... 20-1

50 „ 75 55 ... 6-6

over 75 13 ... 1-5

844 100-0

Temperature Observations. — The temperature of the surface water at
9.30 a.m. on the date of the survey was 51C>1 Fahr., while the following

22

BATHYMETRICAL SUKVEY OF

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•43

THE FRESH-WATER LOCHS OF SCOTLAND. 23

series taken in the deepest part of the loch at 3 p.m. showed that the
water was practically uniform in temperature from surface to bottom : —

Surface 51°-4: Fahr.

10 feet 51°-4

20 „ 51°-5

30 „ 51°-5

50 „ 51°-5

80 „ 51°-2

In the nine lochs included in the foregoing table 681 soundings were
taken, and the aggregate area of the water-surface is almost 5 square
miles, so that the average number of soundings per square mile of surface
is 141. The aggregate volume of water contained in the lochs is estimated
at about 1319 millions of cubic feet. The area drained by these lochs
is 168£ square miles, or nearly thirty-five times the area of the lochs.

24 BATHYMETRICAL SURVEY OF

LOCHS OF THE LAXFORD BASIN.

WITHIN this basin (see Index Map, Fig. 2) five lochs were sounded by
the staff of the Lake Survey, viz.. Lochs More, na h-Ealaidh, Stack, na
Claise Fearna, and nam Breac. The most important of these are Lochs
More and Stack, which drain by the river Laxford into the head of Loch
Laxford — a sea-loch on the west coast of Sutherland. Loch na h-Ealaidh
is directly continuous with Loch More and at the same level, while Lochs
na Claise Fearna and nam Breac drain by independent streams falling
into Loch Laxford on its southern shore. The area draining into these
lochs is about 44 square miles. Lochs More and Stack are situated in a
wild, mountainous district, many of the surrounding peaks exceeding 2000
feet in height, and are famed for their fishing, which is preserved ; Loch
More contains splendid trout, while Loch Stack contains also sea-trout,
Salmo ferox, salmon, and char.

Loch More (see Plate .VIII.). — Loch More (see Fig. 29) lies about
6 miles from Laxford Bridge, and about 10 miles from Scourie, and
approaches to within 2 miles of the head of Loch Merkland, in the Shin
basin. The loch trends in a north-west and south-east direction, and
exceeds 4 miles in length ; the width of the loch is extremely uniform,
so that the mean breadth of the entire loch is very little less than the
maximum breadth, which is under half a mile. The superficial area is
about 940 acres, or nearly 1J square miles, and the area draining into the
loch is only about 12 square miles. The maximum depth of 316 feet was
observed approximately near the centre of the loch. The volume of water
contained in the loch is estimated at nearly 5000 millions of cubic feet,
and the mean depth at 126 feet. The loch was surveyed on September 2
to 6, 1902 ; the elevation of the lake-surface above the sea on commencing
the survey was determined by levelling from bench-mark as being 127*65
feet, but between September 4 and 5 the water rose about 3 inches.
When levelled by the officers of the Ordnance Survey on July 1, 1856,
the elevation was 127'3 feet above sea-level.

Loch More is quite simple in conformation, the bottom sloping down
on all sides towards the deepest part of the loch without any pronounced
irregularity. There is a small basin exceeding 300 feet in depth in the
middle of the loch, based on a single sounding in 316 feet. The 200-feet

THE FRESH-WATER LOCHS OF SCOTLAND.

25

basin is nearly 2J miles in length, distant about three-quarters of a mile
from the two ends of the loch, while the 100-feet basin is over 3 miles, and
the 50-feet basin 3^ miles, in length. The two lines of soundings at the north-
west end of the loch show slight irregularities of the bottom, so that the
50-feet and 100-feet contour-lines become somewhat sinuous in character.
A line of soundings taken about a mile from the south-east end shows a

Engl,sh Hilts

FIG. 2.— INDEX MAP OF THE LAXFOBD, SCOURIE, BADCALL, AND DUABTMOBE BASINS.

very slight undulation in deep water, a sounding in 220 feet having on one
side 225 feet and on the other 234 feet. The areas between the consecutive
contour-lines, and the percentages to the total area, are as follows : —

Feet

0 to 100
100 „ 200
200 „ 300

over 300

Acres.
408
254
232
43

Per cent.

43-6

27-1

24-8

4-5

937

100-0

26

BATHYMETRICAL SURVEY OF

This table shows that the average slope of the bottom is regular, the
areas decreasing with increase of depth, and that the loch partakes of a
flat-bottomed character, as evidenced by the comparatively large area of
the lake-floor covered by more than 200 feet of water.

Temperature Observations. — Two series of temperatures were taken in
Loch More, one towards the north-west end at 5.15 p.m. on September 5,
and the other in the deepest part of the loch at 2 p.m. on September 6,
with the following results : —

i. ii.

Denth in feet September 5, 1902, 5.15 > September 6, 1902, 2 p.m.,
eet< p.m., near N.W. end deepest part of loch in
in 101 feet. 294 feet.

0

54°-0 Fahr.

54° 4 Fahr.

20

—

54°-2 „

25

53°-4 „

—

50

53°-5 „ 53°-9

100

50°-9 „

51°-2

103

50°-6

106

470.3

112-5

47°-3

125

47°-l

150

46°-3

*

200

45°-9

290

450.7

These series show a total range in temperature of 8°-7 from surface to
bottom in the middle of the loch, and of 3°*1 in the 100 feet of water
towards the north-west end. In both series a fall exceeding 2J° was
recorded between 50 and 100 feet, but the greatest fall observed was
between 103 and 106 feet in the middle of the loch — a fall of 3°-3 in the
3 feet of water, or more than 1° Fahr. per foot of depth. The readings
taken towards the north-west end are all slightly lower than those taken in
the middle of the loch at corresponding depths.

Seiches. — Seiches were observed on Loch More on September 2 and 5,
1902, the amplitude in each case being about half an inch, but the period
could not be accurately determined. The fundamental period was about
eleven minutes.

Loch na h-Ealaidh (see Plate VIII.). — Loch na h-Ealaidh is a small
shallow basin at the north-west end of Loch More, the narrows between
them being crossed by stepping-stones, and having a depth of 1 foot on
the date of the survey. The loch is irregularly subcircular in outline,
with a maximum diameter of less than half a mile, its waters covering
an area of about 64 acres. The maximum depth of 8 feet was observed
towards the north-west end, where the river an Earachd flows out, and
the great majority of the soundings were taken in depths exceeding 5 feet.
The volume of water is estimated at 13 million cubic feet, and the mean
depth at 4| feet. The loch was surveyed on September 6, 1902, the

THE FRESH- WATER LOCHS OF SCOTLAND. 27

elevation being the same as that of Loch More. The basin is flat-bottomed
in character, more than half the lake-floor (or 54 per cent.) being covered
by over 5 feet of water.

Loch Stack (see Plate IX.).— Loch Stack lies about a mile to the
north-west of Loch More, the overflow from Loch More being carried
through Loch na h-Ealaidh, and by the short stream an Earachd, into
Loch Stack. Ben Stack, which rises steeply up from the south-western
shore of the loch, forms a striking object in the landscape. The loch
is very irregular in outline, having a fanciful resemblance to the capital
letter H, with one arm longer than the other; in fact, it may almost
be looked upon as two lochs joined by a shallow neck. The general
trend is north-west and south-east, the length of the longer arm being
over 2J miles, and that of the shorter arm nearly 1J miles, while a
line along the axis of maximum depth of one arm across the shallow
neck and along the axis of the other arm would be 3^ miles in length.
The waters of the loch cover an area of about 632 acres (or 1 square
mile), and the area draining into it directly is about 27^ square miles;
but since it receives the overflow from Lochs More and na h-Ealaidh,
the total drainage area is over 40 square miles. The maximum depth of
108 feet was observed in the wide portion of the longer arm, the maximum
depth recorded in the shorter arm being 85 feet. The volume of water
is estimated at about 988 million cubic feet, and the mean depth of the
whole loch at 36 feet. The loch was surveyed on September 6 and 8,
1902, the elevation of the lake-surface above the sea, as determined by
levelling from bench-mark, being 117'65 feet; this is almost identical
with the elevation determined by the officers of the Ordnance Survey on
September 23, 1870, viz. 117'5 feet.

As already indicated, Loch Stack consists of two deep basins separated
from each other by shallow water. The deeper basin is contained in the
longer arm, the maximum depth of 108 feet being recorded about a mile
from the southern end, and about 1J miles from the northern end, of that
arm. This was the only sounding taken in depths exceeding 100 feet,
and here there is a 7 5 -feet area three-quarters of a mile in length, and a
50-feet area over a mile in length. Near the northern end of this arm
there is a small, isolated 50-feet area, based on soundings in 50 and
63 feet, separated from the main 50-feet area by a shoaling of the water
at the narrow constriction in the outline of the loch, about half a mile
from the northern end, where the depth is less than 30 feet. The shallower
basin in the shorter arm of the loch is regular in conformation, the 50-feet
area being about three-quarters of a mile in length, and enclosing a 75-feet
area a quarter of a mile in length, based on soundings in 77, 81, and
85 feet. The last-mentioned sounding was recorded about a quarter of
a mile from the eastern shore. In the shallow neck joining the two arms
of the loch, the deepest sounding recorded was in 16 feet. In one or two

28 BATHYMETRICAL SURVEY OF

places a steep off-shore slope is indicated by the soundings, as, for instance,
off the western shore of the longer arm towards the southern end, where
a sounding in 55 feet was taken about 40 feet from shore, and a little
farther north off the same shore, where a sounding in 24 feet was taken
about 30 feet from shore ; again, off the western shore of the shorter arm,
towards the northern end, a sounding in 57 feet was taken about 60 feet
from shore. The approximate areas between the consecutive contour lines,
and the percentages to the total area of the loch, are as follows : —

Feet. Acres. Per cent.

Oto 25 265 ... 42

25 „ 50 183 ... 29

50 „ 75 ... 146 ... 23

75 ,, 100 .( 33 ... 5

Over 100 .' 5 ... 1

632 100

These figures show that the deep water is not of great extent, more
than 70 per cent, of the lake-floor being covered by less than 50 feet of
water, and more than 40 per cent, by less than 25 feet of water.

Temperature Observations. — The following serial temperatures were
taken in the deepest part of the loch, at 4 p.m., on September 6, 1902 : —

Surface 56°-l Fahr.

25 feet 55°-6 „

50 „ 55°-3 „

100 „ 54°-7 „

These observations show a range of only l°-4 throughout the 100 feet
of water.

Seiche. — A seiche was observed at the west end of the loch, having an
amplitude of three-sixteenths of an inch, but the period could not be
determined.

Loch na Claise Fearna (see Plate X.). — Loch na Claise Fearna is
a little irregular loch lying about half a mile from the southern shore
of Loch Laxford, into which its outflow is carried by the Allt na Claise
Fearna. It is about midway between Laxford Bridge and Scourie, the
road skirting its eastern shore. In outline it is subtriangular, with the
apex pointing in a north-east direction, and covers an area of about
34 acres, while the area draining into it is nearly 1\ square miles. The
maximum depth of 38 feet was observed near the middle of the loch,
between the large central island and the northern shore. The volume
of water is estimated at 20 million cubic feet, and the mean depth at
13J feet. The loch was surveyed on September 10, 1902, when the
elevation of the lake-surface was found to be 135-0 feet above the sea. The
western and southern parts of the loch are shallow, the deeper portion
(exceeding 20 feet in depth) lying to the north and east of the large
central island, and covering an area of about 6 acres, or 1 7 per cent, of the
total area of the loch.

THE FRESH- WATEK LOCHS OP SCOTLAND. 29

Temperature Observations. — The following serial temperatures, taken at
2 p.m. on the date of the survey in the deepest part of the loch, show
a range of only 1°'2 Fahr. throughout the body of water : —

Surface 57°'8 Fahr.

10 feet 57°-2 „

20 „ 57°-0 „

30 „ 56°-6 „

Loch nam Breac (see Plate X.). — Loch nam Breac lies about a mile to
the north-west of Loch na Claise Fearna, near the southern shore of Loch
Laxford, into which its overflow is carried by the Allt a' Mhuilinn. It is
most irregular in outline, with arms projecting in various directions, and
with one large and many smaller islands. From north to south it exceeds a
mile in length, with a maximum breadth of half a mile, the superficial area
being about 142 'acres, or nearly a quarter of a square mile. The maximum
depth of 71 feet was recorded in the southern wide portion of the loch.
The volume of water is estimated at 172 million cubic feet, and the mean
depth at 28 feet. The loch was surveyed on September 9, 1902, but the
elevation of the lake-surface above the sea could not be determined.

Loch nam Breac is extremely irregular in conformation, which is
not surprising, considering that the numerous islands and projecting pro-
montories give rise to many constrictions in the outline. The bottom
sinks in two places below the 50-feet level : (1) in the most southerly
expansion of the loch, where there is a basin a quarter of a mile in
length, enclosing the maximum depth of the loch (71 feet), three sound-
ings having been recorded at that depth near the centre of the expansion ;
and (2) to the south-west of the largest island, where there is a smaller
basin having a maximum depth of 66 feet. These two 50-feet basins cover
an area of about 24 acres, or 17 j^er cent, of the total area of the loch.
Besides these two deep basins, there are six isolated small areas in which
the depth exceeds 25 feet, based in some cases on single soundings, the
largest and deepest lying to the north-east of the largest island, and having
a maximum depth of 44 feet. The area of the lake-floor covered by less
than 25 feet of water is about 76 acres, or 54 per cent, of the total area.

Temperature Observations. — A series of temperatures taken at 6 p.m. on
the date of the survey, in the deepest part of the loch, gave the following
results : —

Surface 57°'l Fahr.

25 feet 57°*0

40 „ 56°-5

45 „ 56°-0

48 „ 52°O

50 „ 52°-0

60 „ 51°-0

This series shows a range of 6°'l, the position of the " sprungschicht "
being well marked, viz. between 45 and 48 feet, where a fall in tempera-
ture amounting to 4° was recorded — a fall exceeding 1° per foot of depth.

30 BATHYMETRIOAL SUEVEY OF

LOCHS OF THE SCOUKIE BASIN.

THE two principal lochs within this basin (Lochs an Laig Aird and
a' Bhaid Daraich) were sounded by the Lake Survey, and were found
to form a complete contrast both in outline and conformation. Loch
an Laig Aird is most irregular in these respects, while. Loch a' Bhaid
Daraich is quite simple. The overflow from Loch an Laig Aird is carried
by the Allt Loch an Laig Aird into Loch a' Bhaid Daraich, which flows by
the short stream Allt a' Mhuilinn into Scourie bay on the west coast
of Sutherland.

Loch an Laig Aird (see Plate XL). — Loch an Laig Aird is situated
about a mile to the north-east of Scourie, and half a mile to the south*
of Loch nam Breac. The waters of the loch almost entirely encircle
a large promontory of land, the connecting isthmus being only about
100 feet across, and cover an area of about 67 acres. The loch is on
the whole shallow, the area of the bottom covered by less than 20 feet
of water being about 51 acres, or 76 per cent, of the total area. The
deepest part of the loch is in the arm stretching south:westwards from the
large promontory, where there is a long narrow basin exceeding 40 feet in
depth, the deepest sounding in 42 feet having been taken close to the
southern shore, about a quarter of a mile from the south-western extremity
of the loch, and only about 40 feet from shore, so that the slope of the
bottom at this place is very steep. A steep slope also occurs near the
south-western extremity of the loch, where soundings in 13 and 14 feet
were taken about 10 feet from shore. In the broad arm to the east of the
large promontory the maximum depth observed was 31 feet, and a similar
depth was found to the north-west of the large promontory. The loch
was surveyed on September 9, 1902, but the elevation of the lake-surface
above the sea could not be determined.

Temperature Observations. — A series of temperatures taken at 5 p.m. on
the date of the survey, in the deepest part of the loch, gave the following
results : —

Surface 570<2 Fahr.

20 feet 56°-2 „

35 „ 56°-l „

Loch a' Bhaid Daraich (see Plate XL). — Loch a' Bhaid Daraich is
situated near the village of Scourie, and little more than a quarter of a

THE FRESH-WATER LOCHS OF SCOTLAND.

31

mile from the head of Scourie bay, but at an elevation of nearly 50 feet
above the sea. The loch trends almost east and west, and is nearly a mile
in length, with a maximum breadth of a third of a mile, its waters covering
an area of about 111 acres, or one-sixth of a square mile. The maximum
depth of 121 feet was observed approximately near the middle of the loch,
but rather nearer the west than the east end. The volume of water is
estimated at 270 million cubic feet, and the mean depth at 55i feet. The
loch was surveyed on September 8, 1902, when the elevation of the lake-
surface was found to be 48*5 feet above the sea, so that the 50-feet contour-
line on the map shows approximately the area of the bottom which falls
below the sea-level.

Loch a' Bhaid Daraich forms a simple flat-bottomed basin, with no
indication of any pronounced irregularity. The contour-lines coincide
approximately with the outline of the loch, having here and there a
slightly sinuous character, and there are in places steep off-shore slopes,
as, for instance, off the northern shore towards the west end, where a
sounding in 45 feet was taken about 40 feet from shore — a gradient ex-
ceeding 1 in 1. The following table gives the approximate areas between
the consecutive contour-lines drawn in at equal intervals of 25 feet, and
the percentages to the total area of the loch : —

Oto 25
25 „ 50

50,, 75
75 „ 100
Over 100

Acres.
26
29
19
22
15

111

Per cent.
23-3
26-2
17-6
19-5
13-4

100-0

These figures show that Loch a' Bhaid Daraich departs from the usual
rule of decreasing area with increasing depth, for in each of the zones
between 25 and 50 feet, and again between 75 and 100 feet, the area is
greater than in shallower water.

Temperature Observations. — A series of temperatures taken at 2 p.m. on
the date of the survey, in the deepest part of the loch, gave the following
results : —

Surface

20 feet

40

42-5

45

50

60
ICO
110

57°-2 Fahr.

57°'l

56C-1

54°-8

52°-0

50°-8

50°-0

48°-9

48°-6

These observations show a range of temperature throughout the body
of water amounting to 8 -'6, the greatest fall being observed between 42J
and 45 feet, viz. a fall of 2°-8 in the interval of 2J feet of depth — a decrease
exceeding \ per foot.

32 BATHYMETRICAL SUEVEY OF

LOCHS OF THE BADCALL BASIN.

OF numerous small lochs draining into Badcall bay, Loch na h-Airidh
Sleibhe was the only one which could be sounded at the time of the visit
of the Lake Survey.

Loch na h-Airidh Sleibhe (see Plate XII.).— Loch na h-Airidh Sleibhe
lies little more than half a mile to the south-east of Loch a' Bhaid Daraich,
the outflowing river running in a south-westerly direction into Badcall
bay. The main body of the loch trends north-west and south-east, and is
two-thirds of a mile in length, with a maximum breadth of one-third of a
mile. Its waters cover an area of about 68 acres, while the area draining
into it is about 1J square miles. The maximum depth of 113 feet was
observed about a quarter of a mile from the north-west end. The volume
of water is estimated at 131 million cubic feet, and the mean depth at
about 44^ feet. The loch was surveyed on September 10, 1902, but the
elevation of the lake-surface above the sea could not be determined. The
loch forms a simple basin, the bottom sloping down on all sides towards
the deepest part, which lies towards the north-west end. The shallower
contours coincide approximately with the outline of the loch, and in some
places deep water approaches close to the shore, as, for instance, off the
northern shore, in the vicinity of the deepest part, where a sounding in 43
feet was taken about 40 feet from shore, indicating a gradient exceeding
1 in 1. The approximate areas between the contour-lines, and the
percentages to the total area of the loch, are given in the following
table :—

Feet. Acres. Per cent.

Oto 25 24 ... 36

25 „ 50 15 ... 22

50 „ 75 15 ... 22

75 „ 100 11 ... 16

Over 100 3 ... 4

^»

68 100

Temperature Observations. — The following series of temperatures was
taken in the deepest part of the loch at 3.30 p.m. on the date of the
survey : —

THE FRESH- WATER LOCHS OF SCOTLAND. 33

Surface 56°'4 Fahr.

10 feet 56°-4 „

25 „ 56°-4 „

40 „ , 56°-4 „

45 „ 53°-6 „

50 „ 51°-1 „

100 „ 49°-5 „

These observations show a total range throughout the body of water
amounting to 6 '9, the superficial layers down to 40 feet being uniform in
temperature, while between the depths of 40 and 50 feet a fall of 5~'3 was
observed.

34 BATHYMETRICAL SURVEY OF

LOCHS OF THE DUAETMOEE BASIN.

WITHIN this basin two lochs were sounded by the Lake Survey, viz.
Loch Allt na h-Airbhe and Loch Duartmore, which drain by a short
stream into the small arm of the sea called Loch na Creige Ruaidhe.
Between these two lochs lies Loch Eucail, which is overgrown with reeds
and apparently shallow.

Loch Allt na h-AirbJie (see Plate XIII.).— Loch Allt na h-Airbhe (or
Upper Loch Duartmore) is the largest in the basin, and trends in a north
and south direction, being nearly two-thirds of a mile in length and one-
third in maximum width. Its waters cover an area of about 83 acres, and
an area of about 8| square miles drains into it. The maximum depth of
60 feet was observed in the south-western part of the loch. The volume of
water is* estimated at 110 million cubic feet, and the mean depth at over
30 feet. The loch was surveyed on September 11, 1902, when the elevation
of the lake-surface above the sea was determined, by levelling from bench-
mark, as being 119*5 feet.

Loch Allt na h-Airbhe is a comparatively deep loch with an uneven
floor. The 25-feet contour-line follows approximately the shore-line, in
some places approaching close to the shore, while the 50-feet basin is
irregular, approaching the eastern shore in its northern portion, and
widening out and approaching the western shore in its southern portion.
In the central portion of the loch is an extensive shoaling, covered by less
than 30 feet of water, surrounded on all sides by deeper water. The deepest
sounding in 60 feet was recorded about 120 yards from the western shore
and about 200 yards from the southern shore. The soundings indicate a
steep off-shore slope in certain positions, as, for instance, off the western
shore near the southern end, where a sounding in 35 feet was taken about
50 feet from shore ; off the same shore, farther north, a sounding in 18 feet
was taken about 20 feet from shore ; while off the eastern shore, near the
northern end, a sounding in 25 feet was taken about 20 feet from shore —
the last-mentioned giving a gradient exceeding 1 in 1. The following
table, giving the approximate areas between the contour-lines and the
percentages to the total area of the loch, shows that a larger area of the
lake-floor is covered by water between 25 and 50 feet in depth (equal to
nearly one-half of the total area) than by water less than 25 feet in
depth : —

THE FRESH-WATER LOCHS OF SCOTLAND. 35

Feet. Acres. Per cent.

Oto25 32 ... 39

25 „ 50 40 ... 48

Over 50 11 ... 13

83 100

Temperature Observations. — A reading at the surface at the north end of
the loch, on commencing the survey on September 11, 1902, gave 58°*6
Fahr., while a series taken at 3.30 p.m., in the deepest part of the loch, gave
the following results : —

Surface 57°-2 Fahr.

10 feet 57°'0 „

25 „ 56°-0 „

50 „ 55°-5 „

These observations indicate a total range of temperature throughout the
body of water amounting to 3°'l, no very decided fall being observed
beneath the surface, but the difference of nearly 1|° between the two
readings at the surface is noteworthy.

Loch Duartmore (see Plate XIII.). — Loch Duartmore is a small, irregular
loch, trending almost east and west, and over a quarter of a mile in length.
Its waters cover an area of about 13 acres, while, since it receives the
overflow from Lochs Allt na h-Airbhe and Eucail, its drainage area is very
large — about llj square miles, or more than 550 times greater than the
area of the loch. The maximum depth of 22 feet was observed near the
east end of the loch. The volume of water is estimated at 3 million cubic
feet, and the mean depth at nearly 6 feet. The loch was surveyed on
September 1J, 1902, when the elevation of the lake-surface was found
to be 81*5 feet above the sea ; this was -i feet lower than the level of Loch
Eucail, and 38 feet lower than that of Loch Allt na h-Airbhe.

Loch Duartmore is on the whole very shallow, the area of the lake-
floor covered by less than 10 feet of water being about 12 acres, or 92 per
cent, of the total area. Only in two places were depths extending 10 feet
recorded : (1) at the extreme eastern end, where soundings in 10 to 22 feet
were taken, and (2) off the northern shore, near the middle of the loch,
where soundings in 12 and 16 feet were taken, the last-mentioned only
about 20 feet from the shore, indicating a steep slope in this position.
Some of the bays are filled with reeds. Temperatures taken in the deep
part at the east end, at 2 p.m. on the date of the survey, gave 55°*0 Fahr.
at the surface and 54°-6 at a depth of 17 feet.

In the ten lochs included in the following table 994 soundings were
taken ; the aggregate area of water surface is 3'35 square miles, so that
the average number of soundings per square mile of surface is 296.
The aggregate volume of water contained in the lochs is estimated at 6679
millions of cubic feet. The area drained by these lochs is over 59 square
miles, or nearly 18 times the area of the lochs.

36

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BATHYMETRICAL SURVEY OF

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THE FRESH-WATER LOCHS OF SCOTLAND.

37

LOCHS OF THE BROOM BASIN.

THE area draining into Loch Broom on the west coast of Scotland is
not an extensive one, the watershed between the eastern and western
drainage systems approaching in this district very close to the west coast.
The basin (see Index Map, Fig. 3) includes, besides numerous small lochs

English Miles

5 10 ,s

FIG. 3.— INDEX MAP OF THE BROOM AND GRUINABD BASINS.

which were not surveyed, three fair-sized lochs, to be dealt with here,
viz. Lochs a' Bhraoin, Droma, and Achall, the two first mentioned drain-
ing by the river Broom into the head of Loch Broom, the last mentioned

38 BATH Y METRICAL SURVEY OF

draining by the Ullapool river into Loch Broom at Ullapool. The Broom
basin is bordered on the south and east by the Conon and Shin basins
belonging to the eastern drainage system, Loch Achall lying about 5 miles
west of Loch an Daimh in the Shin basin, and Lochs Droma and a' Bhraoin
about the same distance north of Loch Fannich in the Conon basin.

Besides the Broom and Ullapool rivers, the basin includes the river
Kanaird, flowing into the wide part of Loch Broom, north of Ullapool, and
the Strathbeg river, flowing into the head of Little Loch Broom, lying to
the south-west of Loch Broom. The scenery of the district is very fine,
and the lochs afford good fishing, though preserved. They all contain
trout, and salmon also are got in Loch Achall. Some years ago Loch
Droma was greatly enlarged, and the fishing vastly improved.

Loch a' Bhraoin (see Plate XIV.). — Loch a' Bhraoin lies about 7 miles
to the south of the head of Loch Broom, surrounded by high hills ; on
the south a' Chailleach rises to 3276 feet above the sea, though the slope
is gentle. The loch trends in a north-east and south-west direction, and
is over 2J miles in length. The maximum breadth is nearly half a mile,
and the mean breadth a quarter of a mile. Its waters cover an area of
about 419 acres, or two-thirds of a square mile, and the area draining
into it is about 13 square miles. The maximum depth of 73 feet was
recorded about half a mile from the north-east end, and nearer the
southern than the northern shore. The volume of water is estimated at
669 million cubic feet, and the mean depth at nearly 37 feet, or half the
maximum depth. The loch was surveyed on August 19, 1902, when the
elevation was found to be 812-5 feet above the sea — about a foot lower
than that determined by the Ordnance Survey officers on August 29, 1868,
viz. 813*4 feet. The keeper stated that the water might fall a few inches
lower, and rise about 5 feet higher, than the level on the date of the
survey. The conformation of the basin is simple, the contours following
approximately the outline of the loch, though the soundings indicate a
few minor undulations.

Temperature Observations. — The temperature of the surface water was
58°-0 Fahr. at 11 a.m. on the date of the survey, and 55°-7 in the after-
noon; while the following serial, taken in the deepest part of the loch
at 4 p.m., showed a range of only 2°'5, or a total range throughout the
waters of the loch of 4°-3.

Surface 560>2 Fahr.

15 feet 54°-9

30 „ 54°-5 „

60 „ 53°-7 „

Loch Droma (see Plate XV.). — Loch Droma (or Druim) lies in the
forest of Braemore, about 8 miles from the head of Loch Broom, and
nearly 6 miles east of Loch a' Bhraoin ; to the north lies Meall Leacachain
(2028 feet), and to the south Beinn Liath Bheag (2173 feet). The loch

THE FRESH-WATER LOCHS OF SCOTLAND. 39

trends in an east and west direction, with a slight bend near the middle,
so that the eastern portion dips south-east, and is lj miles in length, with
a maximum breadth of a quarter of a mile. The superficial area is about
116 acres, and the drainage area about 3 square miles. The maximum
depth of 10 feet was observed about 300 yards from the north-eastern
shore, towards the east end of the loch. The volume is estimated at
32 million cubic feet, and the mean depth at 0^ feet.

The loch was surveyed on August 20, 1902, when the elevation was
found to be 884-1 feet above the sea ; the water could rise only about a
foot higher. The loch is mostly artificial, only a small portion towards
the east end having existed previous to the building of the embankment
at what is now the west end of the loch. This agrees with the evidence
of the levelling, for from observations it was determined that the water
was 11 feet higher than it would be without the embankment, so that a
contour-line drawn in at 11 feet would enclose the original loch. Of
the total area of the present lake-floor, about 84 per cent, is covered by
less than 10 feet of water. The surface temperature on the date of the
survey was 56C*5 Fahr.

Loch Achall (see Plate XV.). — Loch Achall (or Achallt) lies about
2 miles east of Ullapool, in Glen Achall, through which the Rhidorroch
river flows, the shores of both river and loch being, for the most part,
well wooded. The loch is irregular in outline, and trends in an east and
west direction. The length exceeds If miles, the maximum breadth being
nearly half a mile, and the mean breadth over a quarter of a mile. The
superficial area is about 330 acres, or half a square mile, and the drainage
area about 29 square miles. The maximum depth of 70 feet was recorded
near the centre of the loch, but towards the north shore and the west end.
The volume of water is estimated at 401 million cubic feet, and the mean
depth at 28 feet.

The loch was surveyed on August 23, 1902, when the elevation was
found to be 263*4 feet above the sea, or 1J feet lower than that observed
by the Ordnance Survey officers on July 23, 1870, viz. 264-9 feet. The
boatman stated that the water might fall half a foot lower than the level
on the date of the survey, while during the preceding winter it had risen
4J feet above that level, so that the range in level is about 5 feet. The
lake-floor is irregular, the 25-feet area being almost cut into two portions
near the west end, where shallow water runs out from the northern shore
considerably beyond the centre of the loch. The 50-feet area is over
half a mile in length, and approaches close to the shallow water above
mentioned, a distance of less than 250 yards separating a sounding in
55 feet from one in 18 feet.

The temperature of the surface-water on the date of the survey was
56°-0 Fahr.

40 BATHYMETRICAL SURVEY OF

LOCHS OF THE GRUINARD BASIN.

WITHIN this basin eight lochs were sounded by the Lake Survey, viz.
Lochs na Sheallag, Fionn, Dubh, Beannach, na Moine Buige, Eileach
Mhic'ille Eiabhaich, Fada, and na Beiste. The drainage basin under
consideration (see Index Map, Fig. 3) extends from the mouth of Gruinard
bay (between Stattic Point on the east and Creag an Eilean on the west)
to the heights of Beinn Tarsuinn, Mullach Coire Mhic Fhearchair, and
Beinn Bheag, and includes numerous small lochs which could not be
surveyed for lack of boats. As measured by the planimeter on the 1-inch
Ordnance Survey maps the total area of this basin is about 117 square
miles, of which considerably more than one-half, or over 66^ square miles,
drain into the lochs under consideration, as will be seen in the summary
table. Loch na Sheallag flows directly into Gruinard bay by the river
Gruinard, as does Loch Fada by the Allt Bad an Luig, and Loch na
Beiste by the Allt Udrigill, while the remaining lochs mentioned form
a connected series, whose waters are carried into Gruinard bay by the
Little Gruinard river, Loch Dubh adjoining the head of Loch Fionn,
Lochan Beannach flowing into Loch Fionn about midway down the western
shore, Loch na Moine Buige flowing in at the head of Loch Fionn, while
Loch Eileach Mhic'ille Riabhaich carries the outflow from Loch Fionn
into the Little Gruinard river.

Loch na Sheallag (see Plate XVI.). — Loch na Sheallag is situated
about 9 miles to the north-east of Loch Maree, amid wild and magni-
ficent scenery, the head of the loch lying between the heights of An
Teallach (Bidein a' Ghlas Thuill— 3483 feet, and Sgiirr Fiona— 3474
feet) on the north-east, and of Beinn Dearg — 2974 feet — on the south-
west. It contains salmon, sea trout, river trout, and char, but the fishing
is preserved. The loch trends in a south-east and north-west direction,
and is 3| miles in length. It is broadest towards the south-eastern
(inflow) end, where the maximum width of over two-thirds of a mile
occurs, narrowing gradually towards the outflow end. Its waters cover
an area of about 876 acres, or over 1^ square miles, and it drains an area
27 times greater — an area of about 37 square miles. The maximum depth
of 217 feet was observed in the wider part of the loch, about a mile from
the south-east end. The volume of water is estimated at 3948 millions

THE FRESH- WATER LOCHS OF SCOTLAND. 41

of cubic feet, and the mean depth at 103J feet. Loch na Sheallag was
surveyed on August 13 and 14, 1902, when the elevation of the lake-surface
was determined, by levelling from bench-mark, as being 277'7 feet above
the sea ; when visited by the officers of the Ordnance Survey on October
2ii. I>I.N, the elevation was found to be 279*3 feet above sea-level. The
keeper stated that the water might rise 6 feet above, and fall half a foot
below, the level on the date of the survey ; a line of drift was observed
5J feet above the surface of the water.

The main body of Loch na Sheallag forms a simple basin, the deeper
water occupying the wide south-eastern portion, while the water shoals
gradually as the loch narrows in outline towards the north-west. The
lower very narrow portion of the loch, for a distance of about a mile from
the north-west end, is less than 50 feet in depth, except for a small subsi-
diary basin situated about a quarter of a mile from the outflow, in which
depths of 52 to 56 feet were recorded. The slope of the bottom is thus
in striking contrast at the two ends of the loch, for while a depth of 100
feet may be found about 250 feet off the south-eastern end, where the
Abhuinn Srath na Sealga flows in, one must proceed more than a mile
from the opposite end, where the Gruinard river flows out, before en-
countering depths exceeding 100 feet. The 100-feet basin is nearly 2f
miles in length, and the main 200-feet basin is over three-quarters of a
mile in length, with an isolated sounding of 201 feet separated from the
main basin by an interval of one-third of a mile, in which the greatest
depth observed was 191 feet. An inspection of the map shows that the
deeper part of the loch is distinctly flat-bottomed in character, and this is
borne out by the following table, giving the areas between the consecutive
contour-lines drawn in at equal intervals, and the percentages to the total
area of the loch, from which it will be seen that the area between 150 and
200 feet is larger than that between 100 and 150 feet :—

Feet. Acres. Per cent.

Oto 50 229 ... 26-2

50 „ 100 207 ... 23-6

100 „ 150 186 ... 21-2

150 „ 200 202 ... 23-1

Over 200 52 ... 5-9

876 100-0

Temperature Observations. — The surface temperatures taken in Loch
na Sheallag on August 13 and 14, 1902, showed very little variation,
while a series taken beneath the surface in the deepest part of the loch
gave the following results : —

Surface 55°-0 Fahr.

30 feet 53°-0

50 „ 53°-0

75 „ 51°-4

100 „ 48°-5

180 , 47°-9

42 BATHYMETRICAL SURVEY OF

This series shows a total range of temperature amounting to about 7°,
the greatest fall observed being one of about 3° between 75 and 100 feet.

Fionn Loch (see Plate XVII.). — The Fionn Loch, a large irregular
sheet of water, lies less than 3 miles to the north-east of Loch Maree.
It is a good trout loch, and contains also Salmo ferox, but the fishing
is strictly preserved. The lower portion does not lie in a well-marked glen,
though round the upper end rise some precipitous and high mountains.
There are many large islands, and almost everywhere around the shores,
and in places at some considerable distance from shore, large rocks and
boulders rise above the surface of the water. The head of the Fionn
Loch is practically continuous with the Dubh Loch, which are separated
from each other only by an artificial causeway built on a sandbank. When
the water is high this causeway is flooded, though under ordinary circum-
stances the difference of level is about a foot. The matter was the subject
of litigation in 1877, the Lord Ordinary deciding that the lochs were one,
but the House of Lords reversed this decision. In this place the two
lochs are treated separately.

The general trend of the Fionn Loch is from south-east to north-west,
its total length being 5f miles ; it varies greatly in width, the maximum
breadth being about Ij miles, the mean breadth of the entire loch being
nearly two-thirds of a mile. Its waters cover an area of about 2250 acres,
or over 3J square miles, and it drains directly an area of nearly 15 square
miles, but since it receives the outflow from the Dubh Loch, Lochan
Beannach, and Loch na Moine Buige, its total drainage area is about 26J
square miles. The maximum depth of 144 feet was observed in two
places: (1) near the south-eastern end, and (2) in the central part of
the loch opposite the entrance of the stream bearing the outflow from
Lochan Beannach. The volume of water contained in the loch is
estimated at 5667 millions of cubic feet, and the mean depth at 57-f feet.

The Fionn Loch was surveyed on August 4 to 8, 1902, but the elevation
of the lake-surface could not be determined by levelling, owing to the
inability of the surveyors to find bench-marks after prolonged search ;
when visited by the Ordnance Survey officers on September 2, 1870, the
elevation was found to be 558'6 feet above the sea. The keeper stated
that the water may rise 5 feet and fall about 2 feet from the level on
the date of the survey. The bottom of the Fionn Loch is most irregular,
and the contour-lines in most places extremely sinuous in character ; the
north-western end is filled with boulders, which often rise out of com-
paratively deep water in an astonishing manner. The main 50-feet basin
is nearly 4 miles in length, approaching quite close to the south-eastern
end, and extending between the islands called Eilean Fraoch and Eilean
nan Corr-scriach. A second 50-feet basin runs in a north and south
direction, along the centre of the large arm thrown out in a northerly
direction towards the foot of the loch, extending to the west of Eilean nan

THE FRESH- WATER LOCHS OF SCOTLAND. 43

Corr-scriach, and is nearly 2 miles in length j the maximum depth in this
basin, 97 feet, was observed near the southern end of the basin off Eilean
nan Corr-scriach. A third small 50-feet basin occupies the extreme north-
western end of the loch, and has a maximum depth of 78 feet observed
near the north-eastern shore. Within the main 50-feet basin the bottom
sinks in three places below the 100-feet line : (1) a subcircular basin,
two-thirds of a mile in length, situated in the wide portion of the loch at
the south-east end, the 100-feet contour-line approaching to within 300
yards of the shore; (2) an isolated sounding of 101 feet about three-
quarters of a mile farther down the loch ; and (3) about half a mile still
farther down an irregular basin a mile and a half in length. As already
indicated, the maximum depth of the loch (144 feet) was observed in both
of the 100-feet basins numbered 1 and 3, in the former about 530 yards
from the south-east end of the loch, and in the latter about 220 yards from
the western shore of the loch at Eudha Dubh. An inspection of the map
will show how irregular the lake-floor is in the shallower parts of the
loch, and even in the deeper water several conspicuous undulations of the
bottom may be observed. The areas between the consecutive contour-lines
drawn in at equal intervals, aid the percentages to the total area of the
loch, are as follows : —

Feet. Acres. Per cent.

Oto 25 482 ... 21-4

25 „ 50 581 ... 25-8

50 „ 75 463 ... 20-5

75 „ 100 440 ... 19-6

Over 100 285 ... 12-7

2251 100-0

It will be noticed that the area between 25 and 50 feet is larger than
that between the shore and the 25-feet contour, indicating an average slope
steeper near shore than in depths beyond 25 feet.

The surface temperatures taken on August 4 and 5, 1902, showed a
range from 54°-2 Fahr. to 55"'l. In winter the loch is covered all over
with thick ice.

Dubh Loch (see Plate XVII.).— The Dubh Loch is situated in a corrie
forming the natural head of the Fionn Loch, surrounded by high and
steep hills. There is a bend in the outline of the loch, following the
shape of the corrie, the narrower upper portion trending north-west and
south-east, while the wider lower portion trends almost east and west.
The loch is about l£ miles in length, with a maximum breadth of two-fifths
of a mile, the mean breadth being a quarter of a mile. Its waters cover
an area of over 200 acres, or nearly one- third of a square mile, and the
area draining into it is about 6£ square miles. The maximum depth of 88
feet was observed near the centre of the loch, where the outline commences
to widen out towards the west. The volume of water contained in the loch

44 BATHYMETRICAL SURVEY OF

is estimated at 374 million cubic feet, and the mean depth at over 42 feet,
or nearly one-half of the maximum depth. The Dubh Loch was surveyed
at the same time as the Fionn Loch, and the elevation of the lake-surface
was, for the same reason, not determined by levelling.

The conformation of the Dubh Loch is quite a contrast to that of the
adjoining Fionn Loch. Except for one or two irregularities of the lake-
floor, Dubh Loch forms a simple basin, all the contour-lines, though
showing occasional sinuosities, enclosing continuous areas. A bank
covered by 2 feet of water occurs in the middle of the loch, about
300 yards from the south-east end, surrounded by depths exceeding
20 feet ; farther down, a line of soundings running from south to north,
towards the entrance of the Allt Bruthach an Easain, showed a rise of the
bottom from 43 to 38 and 39 feet, sinking again to 51 feet ; still farther
down, another line of soundings running from south to north showed a
remarkable rise of the bottom from 65 to 51 and 48 feet, sinking again to
the deepest recorded sounding (88 feet), whence the soundings shoaled
gradually towards the northern shore. The last-mentioned rise is the
more striking, as it was observed in the deepest part of the loch, and in
close proximity to the maximum depth. The soundings taken in the wide
lower portion of the loch are quite regular, the irregularities above
referred to occurring in the upper half of the loch. The areas between
the consecutive contour-lines, and the percentages to the total area of the
loch, are as follows : —

Feet. Acres. Per cent.

Oto25 50 ... 24-6

25 „ 50 78 ... 38-2

50 „ 75 57 ... 28-2

Over 75 18 ... 9-0

203 100-0

These figures indicate an average slope off-shore much steeper than in
the deeper water, and an inspection of the map shows that the 25-feet
contour follows aprroximately the shore line, approaching in some places
very close to the shore, whereas the 50-feet contour runs, for the greater
part of its course, at a considerable distance from shore, while the upper
part of the loch is occupied by water less than 50 feet in depth.

LocJian Eeannach (see Plate XVII.).— Lochan Beannach is a small
irregular sheet of water lying off the central part of the western shore of
the Fionn Loch, into which it flows by a stream less than a quarter of a
mile in length. The loch consists of two distinct portions, and, as it was
found impossible to get a boat through the passage, the smaller south-
eastern portion was not surveyed, the soundings being limited to the larger
western portion, which is of very peculiar form, almost encircling a large
promontory of land projecting out into the loch from the western shore ;
the narrow neck of land connecting the promontory and the shore is less

THE FRESH- WATER LOCHS OF SCOTLAND. 45

than 50 yards across, and, if it were pierced through, the promontory
wonld become a central island, entirely surrounded by the waters of the
loch. Lochan Beannach is about two-thirds of a mile in length by one-
third of a mile in maximum breadth, covering an area of about 80 acres,
and draining an area of over 4J square miles. The maximum depth of
27 feet was observed in the southern portion of the loch, comparatively
close to the' largest island. The volume of water is estimated at 22
million cubic feet, and the mean depth at 6| feet. The floor of Lochan
Beannach is irregular, with many islands and rocks rising above the
surface of the water. The deepest sounding (27 feet), and a neighbouring
one of 23 feet, were the only ones exceeding 20 feet in depth, while
a sounding of 18 feet was taken in the northern part of the loch, and two
of 14 feet off the north-eastern shore, the area covered by less than 10 feet
of water being about 70 acres, or 88 J- per cent, of the total area.

Loch no JIbine Buige (see Plate XVII.). — Loch na Moine Buige is
a small loch lying at the foot of the Fionn Loch, into which it drains by a
short stream. It trends north-west and south-east, and is about three-
quarters of a mile in length, with a maximum breadth of less than a
quarter of a mile, covering an area of about 55 acres. The maximum
depth of GO feet was observed close to the shore near the south-eastern
end, where the stream flows out of the loch. The volume of water is
estimated at 59 million cubic feet, and the mean depth at over 24J feet.
The variation in the level of the water is slight, the highest drift-mark
observed being only half a foot above the water on the date of the survey
(August 8, 1902), when the loch was at its lowest level. Loch na Moine
Buige is comparatively deep, considering its dimensions, the 25-feet area
extending nearly from end to end, and covering nearly one-half of the
total area of the loch. The 50-feet area is very small, based on the single
sounding of 60 feet close to the south-western shore, so that the slope
of the bottom in that position must be steep. The area covered by less
than 25 feet of water is about 29 acres, or 52 per cent, of the entire area.

Loch Eileach Mhic 'ille Riabhaich (see Plate XVII.).— This little loch
is merely a deepening and widening of the river flowing out of the Fionn
Loch, from which it is separated by two waterfalls ; at its outflow is a
third waterfall, separating it from another smaller expansion of the Little
Gruinard river. It trends north-north-east and south-south-west, and
is nearly three-quarters of a mile in length, with a maximum breadth
of less than a quarter of a mile, covering an area of about 30 acres. It
drains directly an area of about half a square mile, but, since it carries the
outflow from the Fionn Loch, its total drainage area is over 27 square
miles — an area nearly 550 times greater than that of the loch. The
maximum depth of 33 feet was observed in the wide part near the foot
of the loch, where there is a small circular area exceeding 25 feet in

46 BATHYMETRICAL SURVEY OF

depth. The volume of water is estimated at 19 million cubic feet, and the
mean depth at over 14 feet. The area covered by less than 25 feet of
water is about 27 acres, or 90 per cent, of the total area. The loch is not
liable to any great change in level.

Loch Fada (see Plate XVII.).— Loch Fada lies about 2 miles to the
north-north-west of the Fionn Loch, and a similar distance to the south-
west of the head of Gruinard bay. It must not be confounded with
Lochan Fada, situated to the south-east of the Fionn Loch and draining into
the head of Loch Maree, which, though designated by the diminutive term
" lochan," is a much larger sheet of water. This Lochan Fada has already
been described when dealing with the lochs of the Ewe basin.*

Loch Fada trends in a north-east and south-west direction, and is
irregular in outline, with a length of lj miles, and a maximum breadth in
the central portion of the loch of half a mile. Its waters cover an area
of about 145 acres, or nearly one-quarter of a square mile, and it drains an
area ten times grearter, or over 2J square miles. The maximum depth of
56 feet was observed near the centre of the wide central portion of the
loch. The volume of water is estimated at 109 million cubic feet, and the
mean depth at over 17 feet. Loch Fada was surveyed on July 31, 1902,
but the elevation of the lake-surface could not be determined by levelling ;
when visited by the Ordnance Survey officers on August 10, 1870, the
elevation was found to be 498'1 feet above the sea. Loch Fada is most
irregular in conformation, with a few large islands, and with stones and
boulders rising to the surface in many parts. The deepest water is found
in the wide central portion, where there is a small 50-feet basin, based
upon soundings of 51 and 56 feet, enclosed within an irregular 25-feet
basin nearly half a mile in length by over a quarter of a mile in width.
The main 10-feet basin is nearly a mile in length, approaching to within
250 yards from the north-east end. Outside the main 10-feet basin
the bottom sinks in three places below that depth : (1) an isolated sound-
ing of 13 feet in a large bay on the south-eastern shore towards the north-
east end; (2) a sounding of 26 feet recorded about a quarter of a mile
from the south-west end ; and (3) an isolated sounding of 20 feet about
200 yards from the south-west end. Of the entire lake-floor about 45 per
cent, is covered by less than 10 feet of water, and 25 per cent, by more
than 25 feet of water. A series of temperatures taken at 5.30 p.m. on the
date of the survey, in the deepest part of the loch, gave 56°*5 Fahr. at the
surface, 55°'5 at 25 feet, and 55°'3 at 50 feet.

Loch na Beiste (see Plate XVII.). — Loch na Beiste is a small sheet
of water situated on the peninsula of Rudha Mor, Uttle more than half a
mile from the western shore of Gruinard bay. The loch is reputed to be
the abode of a great beast, and Mr. Banks, a former owner, attempted

* See Geographical Journal, vol. 24, pp. 554-557, November, 1904.

THE FRESH-WATER LOCHS OF SCOTLAND.

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48 BATHYMETRICAL SURVEY OF

to pump out the water for the purpose of examining the beast, but he
failed in drawing off the water. The most probable origin of the rumour
about the beast lies in the fact that the moon at a certain time casts the
shadow of two stones upon the water, the shadow resembling the outline of
an animal. The loch is over one-third of a mile in length by one -sixth of
a mile in maximum width, covering an area of about 23 acres, and com-
paratively deep, the maximum depth being 35 feet, and the mean depth
10| feet. The soundings show no irregularities in the conformation of the
lake-floor, the deep water being found towards the east end, while the
south-western portion is shallow. Of the total area about 61 per cent,
is covered by less than 10 feet of water, and 13 per cent, by more than
20 feet of water. The loch was surveyed on August 11, 1902, but the
elevation above the sea could not be determined by levelling. The varia-
tion in the level of the water is said to be about a foot.

From the table on p. 47 it will be seen that in the eleven lochs under
consideration 1141 soundings were taken, and that the aggregate area of
the water-surface is over 7 square miles, so that the average number of
soundings per square mile of surface is 161. The aggregate volume
of water contained in the lochs is estimated at 11,311 millions of cubic
feet. The area drained by these lochs is 111^ square miles, or 15^ times
the area of the lochs.

THE FRESH-WATER LOCHS OF SCOTLAND. 49

LOCHS OF THE GAIKLOCH BASIN.

EIGHT of the lochs within this basin (see Index Map, Fig. 4) were
sounded by the Lake Survey, viz. Lochs an Eilein, na h-Oidche, Dubh,
Bad an Sgalaig, a' Bhealaich, a' Ghobhainn, Braigh Horrisdale, and Bad
a' Chrotha. An attempt was made to sound Loch Clair, but after taking
one line of soundings in a north-easterly and south-westerly direction, on
which a depth of 50 feet was attained, the work had to be abandoned on
account of the leaking of the boat and the strong wind. Loch an Eilein
drains by a stream entering Loch Gairloch at its north-eastern angle?
while Lochs na h-Oidche, Dubh, and Bad an Sgalaig form a connected
series draining by the river Kerry into the south-eastern angle of Loch
Gairloch, and Lochs a' Bhealaich, a' Ghobhainu, Braigh Horrisdale, and
Bad a' Chrotha form another connected series draining by a stream enter-
ing Loch Gairloch on its southern shore. Yellow trout occur in most of
the lochs, and Loch Bad a' Chrotha contains also salmon and sea-trout,
while Loch Bad an Sgalaig contains pike.

Locli an Eilein (see Plate XVIII. ). — Loch an Eilein (or Badh a'
Chream) is situated between Loch Ewe and Loch Gairloch, being distant
from the former rather more than a mile, and from the latter over 2 miles.
The loch is irregular in outline, with a maximum diameter in a north
and south direction of two-thirds of a mile, while from east to west the
greatest width is nearly half a mile, its waters covering an area of about
92 acres. The maximum depth of 34 feet was observed off the central
portion of the south-western shore, where the outflowing stream leaves
the loch. The volume of water is estimated at 58 million cubic feet, and
the mean depth at nearly 14| feet. The loch was surveyed on August 9,
1902, but the elevation of the lake-surface above the sea could not be
determined.

The floor of Loch an Eilein is uneven ; the 10-feet contour-line
coincides approximately with the outline of the loch, but within this
contour the bottom rises in the southern portion of the loch to form two
small islands, and sinks in four places below the 20-feet level. The
principal deep basin lies towards the middle of the south-western shore
at the outflow, where soundings in 28, 30, and 34 feet were taken ; a
depth of 27 feet was found near the southern end, and a depth of 24 feet
towards the northern end, while a sounding in 23 feet was recorded

E

50

BATHYMETRICAL SURVEY OF

English Miles

Bartholomew, Edin!"

o i 2 3 4 £ 10 is

FTG. 4. — INDEX MAP OF THE GAIELOCH, TORRIDON, CARRON, AND ALSH BASINS.

THE FRESH- WATER LOCHS OF SCOTLAND. 51

towards the central portion of the eastern shore. The area of the lake-
floor covered by less than 10 feet of water is about 30 acres, and that
covered by more than 20 feet of water is about 7 acres, so that about
60 per cent, of the bottom is covered by water between 10 and 20 feet
in depth.

Temperature Observations. — The following temperatures taken in the
position of the deepest sounding show little variation in the temperature
of the water : —

Surface 56°-l Fahr.

15 feet 56°-0 „

30 „ 55°-5 „

Loch na Ji-OidcJie (see Plate XIX.). — Loch na h-Oidche (or na-
Houigh) lies about 6 miles to the south-east of Loch Gairloch, and about
3 miles from the shores of Loch Maree. The outflowing stream bifurcates
about half a mile from the loch — one branch flowing into Loch Garbhaig,
and thence into Loch Maree, while the other branch flows into Loch Bad
an Sgalaig, and thence into Loch Gairloch, so that Loch na h-Oidche
may be said to belong both to the Ewe basin and to the Gairloch basin.
The district is mountainous, Beinn an Eoin rising from the eastern shore
of the loch, and Bus-bheinn from the western shore, to heights exceeding
2800 feet, while to the south lie Beinn Dearg (2995 feet) and Beinn
Alligin (3232 feet). The loch trends in a north-north-west and south-
south-east direction, and is If miles in length, with a maxinmm breadth
of nearly half a mile. The superficial area is about 347 acres, or more
than half a square mile, while the drainage area is about 3 square miles.
The maximum depth of 121 feet was observed approximately near the
centre of the loch. The volume of water contained in the loch is estimated
at 816 millions of cubic feet, and the mean depth at 54 feet. The loch
was surveyed on August 7, 1902, but the elevation above the sea could
not be determined; judging from spot-levels on the Ordnance Survey
maps the elevation may be about 1250 or 1260 feet above sea-level.

Loch na h-Oidche forms, on the whole, a simple basin, though with
a slight undulation of the lake-floor in the deep water of the northern
portion, which isolates a sounding in 100 feet from the main 100-feet
basin. The cross-lines of soundings indicate a regularly sloping bottom
from the eastern and western shores towards the centre ; but, while the
third line of soundings from the northern end attains a maximum depth
of 100 feet, the fourth line of soundings farther to the south attains a
maximum of only 89 feet. The 100-feet contour- line is thus interrupted
by the undulation referred to, but the shallower contours all enclose
continuous areas, and coincide approximately with the shore-line, the
75-feet basin being over a mile, and the 50-feet basin nearly 1 J miles in
length. The flat-bottomed character of the loch is indicated by the figures
in the following table, giving the approximate areas between the contour

52 BATHYMETRICAL SURVEY OF

lines drawn in at equal intervals, and the percentages to the total area,
for it will be observed that the area between the 25-feet and 50-feet
contours is smaller than in the deeper zones, while the area of the lake-
floor covered by more than 100 feet of water is very considerable : —

Feet. Acres. Per cent.

Oto 25 107 ... 30-9

25 „ 50 59 ... 17-0

50 „ 75 70 ... 20-1

75 „ 100 63 ... 18-3

Over 100 48 ... 13-7

347 100-0

Temperature Observations. — A series of temperatures taken in the
deepest part of the loch at 5 p.m. on the date of the survey gave the
following results : —

Surface 51°'0 Fahr.

20 feet 51°-0 „

50 „ 50°-5 „

80 „ 47°'2 „

100 „ 46°-8 „

These observations give a total range of temperature throughout the
body of water of 4°'2, the " sprungschicht " occurring between 50 and
80 feet, where a fall of 3°-3 was recorded.

Dabli Loch (see Plate XVIII.).— Dubh Loch lies about 3 miles to the
south-east of Loch Gairloch, and is almost continuous with Loch Bad an
Sgalaig, the stream between them being about 300 yards in length, and
the difference in level about 4 feet. The loch trends in a south-west and
north-east direction, and is nearly a mile in length, varying considerably
in width, the maximum breadth being one-third of a mile. Its waters
cover an area of about 99 acres, and it drains an area of nearly 2J square
miles. The maximum depth of 68 feet was observed near the centre of
the loch. The volume of water is estimated at 136 million cubic feet,
and the mean depth at 31| feet. The loch was surveyed on August 2,
1902, when the elevation of the lake-surface above the sea was ascertained
to be 357-35 feet.

Dubh Loch forms a simple basin, the bottom sloping down on all sides
towards the deepest part in the centre ; the deeper water, however, is
found nearer to the south-western than to the north-eastern end. The
contour-lines follow approximately the trend of the shore-line, but approach
closer to the north-western shore than to the opposite one, indicating a
steeper slope in that direction. Thus, near the middle of the north-
western shore a sounding in 36 feet was taken about 30 feet from shore,
giving a gradient exceeding 1 in 1, and towards the south-west end another
sounding in 36 feet was taken about 40 feet from shore. The 50-feet
basin is half a mile, and the 25-feet basin three-quarters of a mile, in

THE FKESH-WATER LOCHS OF SCOTLAND. 53

length. The area of the lake-floor covered by less than 25 feet of water
is about 39 acres, that covered by water between 25 and 50 feet in depth
is about 37 acres, and that covered by more than 50 feet of water is about
23 acres.

Temperature Observations. — A series of temperatures taken in the
deepest part of the loch at 1.30 p.m. on the date of the survey gave the
following results : —

Surface 56°-0 Fahr.

5 feet 55°-9

10 „ 55°-9

20 „ • 55°-8

50 „ 55°-l

58 „ 52°-2

65 „ 51°'0

These observations give a total range of temperature of 5°*0, the upper
layers of water being practically uniform in temperature, while between
50 and 65 feet there is a fall amounting to 4r°'l.

Loch Bad an Sgalaig (see Plate XVIII.). — Loch Bad an Sgalaig (or
Bad-na-Skallaig, or Batnaskalloch) is somewhat egg-shaped, though
irregular, in outline (see Fig. 30), with a length from north to south
exceeding two-thirds of a mile, and a maximum breadth from east to west
of nearly half a mile. Its waters cover an area of about 137 acres, and
it drains directly an area of over 7 square miles, but since it receives
the overflow from Dubh Loch and Loch na h-Oidche its total drainage
area exceeds 12 J square miles. The maximum depth of 64 feet was
observed approximately near the middle of the loch, though rather nearer
the southern than the northern shore. The volume of water is estimated
at 151 million cubic feet, and the mean depth at 24~ feet. The loch was
surveyed on July 30, 1 902, when the elevation of the lake-surface above the
sea was determined by levelling from bench-mark as being 352*6 feet —
almost identical with the elevation recorded by the Ordnance Survey
officers on July 8, 1870, viz. 352'5 feet above sea-level. Between July 30
and August 2, 1902 (when Dnbh Loch was sounded), the water in Loch
Bad an Sgalaig rose to the extent of 9 inches.

Loch Bad an Sgalaig is simple in conformation ; though the contour-
lines are somewhat sinuous in character, the cross-lines of soundings indicate
a bottom sloping gradually from the shores towards the deep water in the
middle. In places the contour-lines approach close to each other or to the
shore-line, as, for instance, off the central portion of the western shore,
where a sounding in 20 feet was taken about 50 feet from shore, but on the
whole the soundings give no indication of any very steep gradients. The
following table gives the approximate areas between the contour-lines, and
the percentages to the total area of the loch : —

54 BATHYMETRICAL SURVEY OF

Feet. Acres. Per cent.

Oto25 74 ... 54

25 „ 50 45 ... 33

Over 50 18 ... 13

137 100

Temperature Observations.— The following series of temperatures taken
in the deepest part of the loch at 5 p.m. on the date of the survey
shows (as in the case of Dubh Loch) a uniform temperature in the upper
layers of water, with a maximum fall beyond the depth of 50 feet : —

Surface 55°-3 Fahr.

5 feet 55°-3

10 „ 55°-3

20 „ ' 55°-3

30 „ 54°-9

50 „ 54°-0

60 „ 51°-8

Here the total range is only 3C<5, and the fall of temperature between
50 and 60 feet 2°*2 ; while in Dubh Loch the range was larger, the surface
temperature being higher and the bottom temperature lower, and the fall
of temperature greater, than in Loch Bad an Sgalaig.

Loch a1 Bhealaich (see Plate XIX.).— Loch a' Bhealaich (or Vallich) lies
less than a mile to the south-west of Loch na h-Oidche, and is almost
continuous with Loch a' Ghobhainn, the stream flowing from Loch a'
Bhealaich into Loch a' Ghobhainn being only about 200 yards in
length, Loch a' Bhealaich trends in a west-north-west and east-south-
east direction, and is If miles in length, varying considerably in width,
the maximum width being less than half a mile, while the mean breadth of
the entire loch is a quarter of a mile. Its waters cover an area of about
279 acres, or nearly half a square mile, and it receives the drainage
from an area of 5 square miles. The maximum depth of 92 feet was
observed near the middle of the wide eastern portion, about a quarter
of a mile from the east end of the loch and towards the northern shore.
The volume of water is estimated at 398 millions of cubic feet, and the
mean depth at 32 J feet. The loch was surveyed on August 8, 1902, but
the elevation of the la.ke-surface above the sea could not be determined.

Loch a' Bhealaich is complex in conformation, including three deep
basins exceeding 50 feet in depth, separated by shallower water, the
shoalings coinciding with constrictions in the outline. The largest and
deepest basin is contained in the wide eastern portion of the loch, where
there is a 50-feet area nearly half a mile in length, by a quarter of a mile
in maximum width. Separated from this eastern basin by a short interval,
in which a maximum depth of 40 feet was observed, is a small central
50-feet area, based on soundings in 51, 55, and 55 feet, a quarter of a mile
in length. This central area is separated by a longer interval, in which a

THE FRESH- WATER LOCHS OF SCOTLAND. 55

maximum depth of 44 feet was observed, from the small western 50-feet
area, based on soundings in 51 and 58 feet, distant about 200 yards from
the western end of the loch. The 25-feet contour encloses a continuous
area from end to end, coinciding approximately with the shore-line. Off
the southern shore, about half a mile from the western end, were some
sunken rocks and stones covered by 1 to 2 feet of water. The following
table gives the approximate areas between the contour-lines, and the per-
centages to the total area of the loch : —

Feet. Acres. Per cent.

Oto25 121 ... 43

25 „ 50 104 ... 38

50 „ 75 37 ... 13

Over 75 17 ... 6

279 100

The surface temperature on commencing the survey at 12.30 p.m.
on August 8, 1902, was 54C>0 Fahr.

Loch a' Ghobhainn (see Plate XIX.). — Loch a' Ghobhainn (or Gouen)
lies immediately to the north-west of Loch a' Bhealaich, and about 2
miles to the west of Loch na h-Oidche. The outflow is carried into Loch
Gaineamhach, lying about a mile to the west-north-west, which was not
surveyed because there was no boat on it. Loch a' Ghobhainn is irregularly
elliptical in outline, and trends in a north-west and south-east direction,
being about three-quarters of a mile in length and one-third of a mile in
maximum breadth. Its waters cover an area of about 98 acres, and it
drains directly an area of over a square mile, but since it receives the
superfluent waters from Loch a' Bhealaich its total drainage area exceeds
6 square miles. The maximum depth of 28 feet was observed approxi-
mately in the middle of the loch. The volume of water is estimated at
54 million cubic feet, and the mean depth at 12 J feet. The loch was
surveyed on the same day as Loch a' Bhealaich, August 8, 1902, but the
elevation of the lake-surface above the sea could not be determined ;
judging from spot-levels and contour-lines on the Ordnance Survey maps
the elevation of both these lochs must be just above the 1000 feet level.

Although the 10-feet and 20-feet contours enclose continuous areas, the
floor of Loch a' Ghobhainn is rather irregular, especially in the south-
eastern half of the loch, as evidenced by the sinuous character of the
contours. The deeper water occurs in the north-western portion of the
loch, and approaches close to the north-west end, a sounding in 27 feet
having been taken within 100 yards from that end. Near the middle
of the loch in the vicinity of the deepest sounding a rise of the
bottom, covered by 15 feet of water and with deeper water on both sides,
was observed, and similar irregularities occur towards the south-east, where
a sounding in 6 feet was taken in a central position, and one in 9 feet near
the south-western shore, surrounded by deeper water. Near the south-east

56 BATHYMETRICAL SURVEY OF

end comparatively deep water, maximum 17 feet, was found, separated from
the main body of deep water by lesser depths, maximum 11 feet. The
area covered by less than 10 feet of water is about 35 acres, that covered by
more than 20 feet of water is about 13 acres, while that covered by water
between 10 and 20 feet in depth is about 50 acres, or one-half of the entire
lake-floor.

Loch Braigh Horrisdale (see Plate XVIII.). — Loch Braigh Horrisdale
(or Horisdel) lies about 4 miles to the north-west of Loch a' Ghobhainn,
and little more than a mile from the head of Loch Shieldaig, the south-
eastern extension of Loch Gairloch ; but its outflow is carried by a stream
2 miles in length, entering Loch Gairloch farther to the west. The loch
is irregular in outline, somewhat in the form of a triangle, with the apex
pointing in an easterly direction, and with the base-line protruding towards
the centre of the triangle. Measured along the axis of maximum depth
from north to south, the length exceeds three-quarters of a mile, the
maximum breadth being one-third of a mile. The superficial area is about
91 acres, and the area draining directly into the loch is about 8 square
miles, but since it receives the overflow from Loch a' Bhealaich and Loch
a' Ghobhainn, the total drainage area exceeds 14 square miles. The
maximum depth of 51 feet was observed in two places in a central position.
The volume of water is estimated at 62 million cubic feet, and the mean
depth at 18 feet. The loch was surveyed on August 6, 1902, but the
elevation of the lake-surface above the sea could not be determined ;
when levelled by the officers of the Ordnance Survey on June 23, 1870,
the elevation was found to be 302'3 feet above sea-level.

Loch Braigh Horrisdale is, on the whole, shallow, since 83 per cent, of
the lake-floor is covered by less than 25 feet of water, and 44 per cent, by
less than 10 feet of water. The lines of soundings all indicate a regular
and gentle slope from the shores towards the centre ; but there is a slight
shoaling of the water at the entrance of the inflowing river, which isolates
a small 20-feet basin to the south from the main basin to the north. The
deeper water lies in the north-eastern portion of the loch, where there is
a small 50-feet area, based on two soundings in 50 feet and two soundings
in 51 feet; and it is curious to note that the two 50-feet soundings are
within the two deeper ones, indicating a slight rise of the bottom in the
deepest part of the loch. The area covered by less than 25 feet of water
is about 75 acres, while that covered by more than 25 feet of water is about
16 acres.

Temperature Observations. — The following series of temperatures was
taken in the deepest part of the loch at 6 p.m. on the date of the survey : —

Surface 55°'l Fahr.

10 feet 54°-9 „

20 „ 54°-8 „

40 „ 53°-8 „

50 , 53°-2

THE FRESH- WATER LOCHS OF SCOTLAND. 57

This series shows a total range of 1°*9 from surface to bottom, the
npper layers of water being nearly uniform in temperature, while between
20 and 50 feet the fall was l°-6.

Loch Bad a' Chrbiha (see Plate XVIII.). — Loch Bad a' Chrotha (or
Badachro) is a shallow expansion of the river, much overgrown with weeds,
lying within half a mile of the southern shore of Loch Gairloch. It is
irregular in outline and conformation, covering an area of about 44 acres,
and draining directly an area of about 7 square miles ; but since it receives
the overflow from Lochs a' Bhealaich, a' Ghobhainn, and Braigh Horris-
dale, its total drainage area exceeds 21 square miles — an area three
hundred times greater than that of the loch. The maximum depth of
23 feet was observed in the north-eastern part of the loch. The volume
of water is estimated at 12 million cubic feet, and the mean depth at 6 feet.
The loch was surveyed on August 6, 1902, but the elevation of the lake-
surface above the sea could not be determined. The area of the lake-floor
covered by less than 10 feet of water is about 40 acres, or 90 per cent, of
the total area ; in five places soundings in depths exceeding 10 feet were
recorded, one of them exceeding 20 feet, i.e. the deepest sounding in
23 feet. The temperature of the surface water on the date of the survey
was 58°-4 Fahr.

58 BATHYMETRICAL SURVEY OF

LOCHS OF THE TOEBIDON BASIN.

ONLY two lochs within the Torridon basin were sounded by the Lake
Survey, viz. Loch Damh, which drains into Upper Loch Torridon, and
Loch Dhugaill, which drains into Loch Shieldaig, a branch of Loch
Torridon. Loch Lundie, which also drains into Loch Shieldaig, and
other smaller lochs, could not be surveyed for lack of facilities. The
district abounds in deer forests and lofty mountains, and the scenery is
of a true Highland character. Loch Damh contains salmon, sea-trout, and
salmo ferox, as well as trout, while Loch Dhugaill contains salmon, sea-
trout, and yellow trout ; but the fishings are preserved.

Loch Dhugaill (see Plate XX.).— Loch Dhugaill (or Dougall) lies at
the foot of Glen Shieldaig (see Fig. 31), about a mile from the head of
Loch Shieldaig, the precipitous slopes of Ben Shieldaig rising on the east.
The loch trends in a north-west and south-east direction, and is narrowly
triangular in outline, with the apex to the north-west. The length exceeds
half a mile, and the maximum breadth at the south-east end is about a
quarter of a mile. The superficial area is about 38 acres, and the drainage
area over 4 square miles. The maximum depth of 108 feet was observed
in the middle of the loch towards the south-east end. The volume of
water is estimated at 63 million cubic feet, and the mean depth at 38^ feet.
The loch was surveyed on August 22, 1902, but the elevation could not
be determined; on July 1, 1869, the Ordnance Survey officers found the
elevation to be 84*3 feet above the sea. The conformation of the basin is
simple, the deeper water lying at the wide upper end of the loch. About
74 per cent, of the lake-floor is covered by less than 50 feet of water, while
about 7 per cent, is covered by more than 100 feet of water. Temperatures
taken in the deepest part of the loch gave 57°*0 Fahr. at the surface and
45°-7 at 100 feet, showing a range of 11°'3.

Loch Damh (see Plate XX,). — Loch Damh lies about a mile from the
southern shore of Upper Loch Torridon, into which it drains by the river
Balgay, Beinn Damph (2958 feet) rising from the eastern shore of the
loch (see Fig. 32). The two little lochs, an Loin and Coultrie, at the
head of Loch Damh, were not surveyed, but were seen to be largely filled
with weeds, and are apparently shallow. Loch Damh trends nearly north
and south, and is somewhat V-shaped in outline, with the limbs of the V

THE FRESH-WATER LOCHS OF SCOTLAND.

59

very much depressed. It is nearly 4 miles in length, with a maximum
breadth of three-quarters of a mile, and a mean breadth of one-third of a
mile. Its waters cover an area of about 851 acres, or 1| square miles, and
it drains an area of 41 square miles. The maximum depth of 206 feet
was observed at the widest part of the loch, at the junction of the two
limbs of the V. The volume of water is estimated at 2183 millions of
cubic feet, and the mean depth at 59 feet. The loch was surveyed on
August 21 and 22, 1902, when the elevation was found to be 129'0 feet
above the sea, nearly identical with that determined by the Ordnance
Survey officers on July 29, 1870, viz. 129-2 feet. The range in level is
4 to 5 feet, the water being lower than usual for the season at the time
of the survey, and might rise 3 or 4 feet higher, and fall a foot lower.

Loch Danih is complex in conformation, there being three 25-feet
basins separated from each other by shallower water. The northern basin
is unimportant, with a maximum depth of 34 feet. The southern basin is
of simple form, over three-quarters of a mile in length, and encloses a
]""-feet basin over half a mile in length, having a maximum depth of
135 feet. The central basin is the largest and deepest, being 2J miles in
length, and enclosing towards its southern end a small 200-feet basin,
elliptical in form, and nearly a quarter of a mile in length. At the
northern end of this central basin the 50-feet contour is irregular, shallow
water extending towards the middle of the loch, and approaching very
close to a small area slightly exceeding 100 feet in depth. Here a sound-
ing in 42 feet was recorded less than 30 yards from one in 115 feet, giving
a gradient of nearly 1 in 1. The shore-slopes to the east of the 200-feet
basin are fairly steep, a sounding in 84 feet having been taken about
40 yards from shore, and one in 134 feet about 90 yards from shore.

Temperature Observations. — Serial temperatures were taken in the
deepest part of the loch on August 21, and in the southern basin on
August 22, with the following results :—

Depth.

Central basin.
5.30 p.m., Ang. 21, 1902.
204 feet.

Southern basin.
10.45 a.m., Aug. 22, 1902.
127 feet.

0 Fahr.

0 Fahr.

Surface

56-5

56-8

10 feet

56-5

30

56-2

60

56-0

55-1

100

48-5

48-1

120

48-0

150

43-1

180

42-2

200

42-2

—

These observations show a range of 14D>6 Fahr., the superficial layers
of water down to 50 feet being nearly uniform in temperature, while
between 50 and 100 feet there was a fall of 7C and 7J7. In the deepest
part of the loch there was a further fall of 5J0 between 100 and 150 feet.

60 BATHYMETKICAL SURVEY OF

LOCHS OF THE CARRON BASIN.

THERE are two Carron rivers in Ross-shire, one flowing into the
Dornoch firth on the east coast, the other into Loch Carron on the west
coast. The latter is the one under consideration ; it rises at the head of
Glen Carron, and in its course passes through Lochs Sgamhain and Dhug-
haill, which are here to be described. The scenery is grand and
mountainous, and the fishing in the lochs, which is preserved, includes
salmon, sea-trout, salmo ferox, and char.

Loch Sgamhain (see Plate XXI.). — Loch Sgamhain (or Scaven) lies
near the head of Glen Carron, with Beinn na Feusaige (2000 feet) rising
on the north, and Moruisg (3026 feet) on the south, and distant only about
2| miles from Loch Gown in the Conon basin, belonging to the eastern
drainage system. The loch trends in a north-east and south-west direction,
and exceeds a mile in length by one-third of a mile in maximum breadth.
Its waters cover an area of about 141 acres, and it drains an area of 1\
square miles. The maximum depth of 72 feet was observed near the centre
of the loch. The volume of water. is estimated at 165 million cubic feet,
and the mean depth at nearly 27 feet. The loch was surveyed on August 8,
1902, when the elevation was found to be 491 '6 feet above the sea, as
compared with 490'9 feet observed by the Ordnance Survey officers on
August 12, 1870.

The shores of the loch are comparatively simple, but near the west end
a considerable promontory known as Cnoc nan Sguad projects into the
loch from the northern shore. There are two small islands in the centre
of the loch, opposite Cnoc nan Sguad ; between the islands and the
promontory a depth of 32 feet was recorded, but between the islands and
the southern shore the depth does not exceed 12 feet. The 25-feet basin
extends nearly from end to end of the loch, but is very narrow in its
western portion. The wide eastern portion encloses the 50-feet basin,
which occupies a central position, and is about one-third of a mile in
length, approaching close to the promontory of Cnoc nan Sguad on its
eastern side. The area of the lake-floor covered by less than 25 feet of
water is about 75 acres, or 53 per cent, of the total area.

Loch Dhughaill (see Plate XXII.).— Loch Dhiighaill (or Doule) lies
about 4 miles from the head of Loch Carron, and about 6 miles south-west
of Loch Sgamhain. It is surrounded by lofty mountains, Fuar Tholl

THE FRESH- WATER LOCHS OF SCOTLAND. 61

(2968 feet) rising to the north-west, and Creag a' Chaoruinn Eagan
(22(30 feet) to the south. On its south side the shore of the loch rises
steeply to the ridge of Creag an Eilein, the highest part of which
(1137 feet) is about a quarter of a mile distant. The loch trends north-
east and south-west, and is 2 miles in length, with a maximum breadth
of less than half a mile near the north-east end, whence it tapers oflf
towards the south-west, the lower end for half a mile being merely a series
of small expansions of the river Carron. Its waters cover an area of about
283 acres, and it drains directly an area of 3l| square miles, but since it
receives the overflow from Loch Sgamhain the total drainage area is 39
square miles. The maximum depth of 179 feet was observed opposite the
highest part of Creag an Eilein, less than half a mile from the north-east
end. The volume of water is estimated at 823 million cubic feet, and the
mean depth at nearly 67 feet. The loch was surveyed on August 6 and 7,
1902, when the elevation was found to be 93*1 feet above the sea.

The main body of the loch is simple in conformation, the contour-lines
following approximately the shore-line, but there are two 100-feet basins,
the main basin being over three-quarters of a mile in length, and approach-
ing very close to the north-east end, soundings in 108 and 111 feet having
been taken about 120 yards from shore; the smaller basin is based on a
single sounding in 105 feet, and is separated from the main basin by a
slight shoaling, covered by 97 feet of water, north of Eilean Mor. There
are two small basins over 25 feet in depth in the river-expansions at the
south-western end of the loch, the larger having a maximum depth of
32 feet, the smaller based on a sounding in 28 feet.

Temperature Observations. — A series of temperatures taken in the
deepest part of the loch at 4.30 p.m. on August 7, 1902, gave the following
results : —

Surface 54°-5 Fahr.

25 feet 54°-5

50 „ 54°-0

60 „ 53°-5

70 „ 50°-0

75 „ 49°-3

100 „ 47°-5

165 „ 47°'0

These observations show a range from surface to bottom of 7^°, a fall
of 3J° being recorded between 60 and 70 feet, while the decrease in
temperature both above and below the " sprungschicht " is gradual.

From the following table it will be seen that in the twelve lochs under
consideration nearly 1100 soundings were taken, and that the aggregate
area of the water surface is nearly 4 square miles, so that the average
number of soundings per square mile is 281. The aggregate volume of
water contained in the lochs is estimated at 4921 millions of cubic feet.
The area drained by these lochs is nearly 98i square miles, or 25 times
the area of the lochs.

62

BATHYMETRICAL SURVEY OF

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THE FRESH-WATER LOCHS OF SCOTLAND. 63

LOCHS OF THE ALSH BASIN.

THE area draining into Loch Alsh and its two branches — Loch Duich
and Loch Long — is an extensive one, but only three small lochs within the
basin were sounded by the Lake Survey. The two more important ones,
Loch na Leitreach and Loch a* Bhealaich, drain by the River Elchaig into
the head of Loch Long ; while the third and smallest one, Loch Anna,
drains into the Allt Gleann Udalain, which flows into Loch Alsh on its
northern shore. The large area draining into Loch Duich is almost
entirely devoid of lakes. The scenery of the district is grand and
mountainous, many of the peaks exceeding 3000, and some of them
exceeding 3500, feet in height.

Loch na Leitreach (see Plate XXIIL). — Loch na Leitreach lies about
six miles east of the head of Loch Long, and about the same distance
north-east of the head of Loch Duich. It trends in a south-west and
north-east direction, and is widest towards the north-eastern end, narrow-
ing gradually towards the outflow at the south-western end. It exceeds
a mile in length, with a maximum breadth of one-fifth of a mile, the
superficial area being about 84 acres. The area draining into it is about
12 square miles, including Loch Muirichinn (not surveyed) lying at the
head of the glen at a high elevation. The maximum depth of 88 feet was
observed near the middle of the loch. The volume of water is estimated1
at 147 million cubic feet, and the mean depth at over 40 feet. The
formation of the main basin is simple, the deeper water occupying the
wide upper portion of the loch, a depth of 65 feet having been recorded
close to the upper end, and the maximum depth of 88 feet about half a mile
down the loch. Xear the south-west end a depth of 31 feet was found,
separated from the main basin by depths of 14 and 15 feet.

The loch was surveyed on October 10, 1904, when the elevation was
supposed to be about 275*3 feet above the sea, that is to say, the water just
covered the position indicated on the 6-inch Ordnance Survey map for a
bench-mark placed at that altitude on the south side of the road at the
north angle of the loch. The temperature of the water was practically
uniform, the reading at the surface being 467'2 Fahr., and at a depth of 80
feet 46-0.

Loch a' Bhealaich (see Plate XXIV.).— Loch a' Bhealaich lies about 4£
miles east of the head of Loch Dutch, and 3^ miles south of Loch na

64 BATHYMETEICAL SUKVEY OF

Leitreach. The loch trends nearly north and south, and is irregular in
outline, two-thirds of a mile in length, and over a quarter of a mile
in maximum breadth, the superficial area being about 78 acres, while the
area draining into it is nearly 2 square miles. The maximum depth of 44
feet was found towards the lower (northern) end, in the vicinity of the
two islands situated in the lower half of the loch. The volume of water
is estimated at 56 million cubic feet, and the mean depth at 16 J feet.
The loch was surveyed on October 25, 1904, when the elevation was
found to be 1242'6 feet above the sea, as compared with 1242-3 feet
determined by the officers of the Ordnance Survey on August 6, 1867.
Serial observations taken in the deepest part of the loch showed that the
temperature of the water was practically uniform, the reading at the
surface being 46°-4 Fahr., and at 25 feet and at the bottom 46°-2.

Loch Anna (see Plate XXIII.). — Loch Anna lies about 1J miles from
the northern shore of Loch Alsh at Ardelve. It trends in a north-west
and south-east direction, and is one-third of a mile in length, the super-
ficial area being about 24 acres, and the drainage area about half a square
mile. The volume is estimated at 13 million cubic feet, and the mean
depth at nearly 13 feet. The wide northern portion contains the deepest
basin, the maximum depth of 27 feet being found close to the north-
eastern angle of the loch, while at the upper end there is a small basin
based on soundings in 20 and 21 feet. The loch was surveyed on October
24, 1904, the elevation being estimated from spot-levels at about 1040 feet
above the sea. The temperature of the water was found to be uniform,
readings at the surface and at a depth of 20 feet giving 44°*6 Fahr. in
each case.

THE FRESH-WATER LOCHS OF SCOTLAND.

G5

LOCHS OF THE ALINE BASIN.

THE area draining into Loch Aline, a branch of the Sound of Mull,
includes three lochs which were sounded by the Lake Survey, viz. Lochs
Doire nam Mart, Arienas, and Tearnait (see Index Map, Fig. 5). Loch

English Miles

FIG. 5. — INDEX MAP OF THE ALINE BASIN AND THE ISLAND OF LISMORE.

Doire nam Mart lies little more than a mile to the south of the head of
Loch Teacuis, a branch of Loch Sunart, but drains in the opposite direc-
tion by a short stream into the larger Loch Arienas, the overflow from
which is carried by the river Aline into the head of Loch Aline. Loch
Tearnait lies to the east of the head of Loch Aline, into which it drains by

F

G6 BATHYMETUICAL SURVEY OF

an independent stream, the Rannoch river. The fishings in these lochs
are strictly preserved.

Loch Doire nam Mart (see Plate XXV.). — Loch Doire nam Mart (or
Durinemartj or Durinemast) lies about 3J miles north-west of Loch Aline.
It trends in a north-west and south-east direction, and is nearly two-thirds
of a mile in length, the maximum breadth exceeding a quarter of a mile.
Its waters cover an area of about 72 acres, and the area draining into it
exceeds 2 square miles. The maximum depth of 48 feet occupies a
central position, but rather nearer the northern than the southern end.
The volume of water is estimated at 67 million cubic feet, and the mean
depth at over 21 feet. The loch was surveyed on August 18, 1904, when
the elevation was found to be 37*2 feet above the sea; the Ordnance
Survey officers found the elevation to be 36*6 feet above sea-level on
March 16, 1867. The loch is simple in conformation, about 57 per cent,
of the lake-floor being covered by less than 20 feet of water.

•

Loch Arlenas (see Plate XXV.). — Loch Arienas (or Ari-Innes) lies
about 2 miles north of Loch Aline, and trends in a west-north-west and
east-south-east direction, being widest in the central part, and narrowing
towards both ends. It is nearly 2 miles in length, with a maximum
breadth of three-quarters of a mile, the mean breadth being about one-
third of a mile. The shore-line is regular on the northern side, except for
the projecting delta at the mouth of the Arienas burn, the southern shore
being more irregular. The loch covers an area of about 420 acres, or two-
thirds of a square mile, and the area draining into it exceeds 8 square
miles, including that draining into Loch Doire nam Mart. The maximum
depth of 116 feet was found almost in the centre of the loch. The volume
of water is estimated at 1035 millions of cubic feet, and the mean depth at
56J feet. The loch was surveyed on August 18 and 19, 1904, when the
elevation was 31*3 feet above the sea; on March 4, 1867, the Ordnance
Survey officers found the elevation to be 36'0 feet above sea-level, or
nearly 5 feet higher than in 1904. Thus in March, 1867, Loch Doire
nam Mart was only half a foot higher than Loch Arienas, whereas in
August, 1904, it was about 6 feet higher.

Loch Arienas forms a simple basin, the contour-lines coinciding
approximately with the outline, but approaching closer to the northern
shore, where the slope is steepest. The following table, giving the areas
between the contour-lines, indicates the flat-bottomed character of the
basin : —

Feet. Acres. Per cent.

Oto 25 110 ... 26-1

26 „ 50 85 ... 20-2

50 „ 75 78 ... 18-6

75 „ 100 77 ... 18-5

Over 100 70 ... 16-6

420 100-0

THE FRESH-WATER LOCHS OF SCOTLAND. 67

Temperature Observations. — Serial temperatures were taken in the
deepest part of the loch at noon on August 19, 1904, with the following
results : —

Surface 59°'5 Fahr.

25 feet 59°-0

50 „ 57°-0

56 „ 54°-0

62 „ 52°-6

75 „ 50°-2

110 „ 48°-5

The total range from surface to bottom was 11°, the greatest fall being
one of 3~ between 50 and 56 feet — a fall equal to half a degree per foot
of depth.

Loclt Twmiait (see Plate XXV.).— Loch Tearnait (or Ternate) lies
about 4 miles south-east of Loch Arienas, and less than 3 miles east of
the head of Loch Aline. The loch trends almost east and west, and is
nearly three-quarters of a mile in length, with a maximum breadth of over
one-third of a mile. Its waters cover an area of about 106 acres, and the
drainage area exceeds 4 square miles. The volume of water is estimated
at 75 million cubic feet, and the mean depth at 16 feet. At the east end
there is a small island at the entrance of the main inflow, and near the
middle of the loch there is another small island. The deepest part of the
loch lies to the west of this island, the maximum depth of 39 feet having
been found about midway between it and the west end. To the east and
south-west of this island soundings in 24 to 28 feet were taken. The loch
was surveyed on August 18, 1904, but the elevation above the sea could
not bo determined; judging from spot-levels it is apparently about 460
feet above sea-level. Temperatures taken in the deepest part of the loch
showed a range of less than 2 Fahr. from surface to bottom : —

Surface 59°-5 Fahr.

25 feet 58°-0 „

37 , 57°-6

68

BATHYMETEICAL SURVEY OF

LOCHS OF THE LEVEN BASIN.

THE area draining by the river Leven into Loch Leven, a branch of Loch
Linnhe, is an extensive one, and includes four lochs which were sounded
by the Lake Survey, viz. Loch a' Bhaillidb, Lochan na Salach Uidhre,
Lochan Inbhir, and Loch Eilde Mor (see Index Map, Fig. 6). These
four lochs receive the drainage from nearly 60 square miles of mountainous

English Miles

BartholomenEdirf

FIG. 6. — INDEX MAP OF THE LEVEN BASIN.

country, some of the peaks approaching 3000 feet in height, while
Binnein Mor, to the north-east of Loch Eilde Mor, attains an elevation of
3700 feet above the sea. Loch Eilde Mor is situated in Inverness-shire,
draining by the Allt na h-Eilde into the river Leven, while the other three
lochs lie on the boundary-line between Inverness-shire and Argyllshire,
and may be looked upon as merely a series of expansions of the river
Leven. The fishings in the lochs are preserved.

Loch a* Bhaillidh (see Plate XXVI.).— Loch a' Bhaillidh (or Vallie)
lies about 5 miles from Rannoch station on the West Highland Railway,
and equi-distant from Loch Laidon in the Tay basin, and Loch Ossian in
the Lochy basin. It is irregular in form, trending nearly east and west, and
exceeding a mile in length, with a maximum breadth of about half a mile,
the mean breadth being over a quarter of a mile. The loch is comparatively

THE FRESH-WATER LOCHS OP SCOTLAND. 69

shallow, the maximum depth being 20 feet, and the mean depth 7J feet.
The superficial area is abouta!84 acres, of which 74 per cent, is covered by
less than In feet of water. The volume of water is estimated at 61
million cubic feet, and the drainage area extends to 30 square miles. The
elevation above the sea could not be determined, but the Ordnance Survey
maps give it as 1<>24 feet, though the date is not indicated.

There are three basins in which the depth exceeds 10 feet : one at the
east end enclosing the maximum depth of the loch (20 feet), one in the
central part of the loch having a maximum depth of 12 feet, and one at
the west end having a maximum depth of 16 feet, taken close to a
promontory projecting from the northern shore.

Temperature Observations. — Serial temperatures taken in the deepest
part of the loch on May 19, 1903, gave the following results : —

Surface 53°-0 Fahr.

10 feet ... 50°-0 „

15 „ 46°-2 „

20 „ 46°-0 „

The range of temperature from surface to bottom was 7°, the greatest
fall being one of 3°'8 between the depths of 10 and 15 feet.

Lochan na SalacJi Uidhre (see Plate XXVI.).— This loch lies to the
west of Loch a' Bhaillidh, and is most irregular in outline, consisting of
several divisions varying in size, connected by short channels. The two
easternmost divisions could not be surveyed, being cut off from the main
loch by a narrow channel, with a fall of about 5 feet. There is also a
slight fall of 6 inches to a foot in the channel leading into the westernmost
division of the loch, though the Ordnance Survey maps give the same level
(In22 feet above the sea) for the entire loch west of the falls. On the
whole, the loch is shallow, with many islands and boulders. The length
of the portion surveyed is nearly 2 miles from east to west, and the
maximum breadth over one-third of a mile. The area is about 245 acres,
of which 86 per cent, is covered by less than 10 feet of water. In nine
places soundings deeper than 10 feet were taken, mostly restricted areas
varying from 10 to 12 feet in depth, and only in three places were depths
of 2' > feet and over recorded: (1) in the narrower portion between the two
peninsulas called Rudha Dubh-mor and Rudha Dubh-beag at the east end,
where a sounding in 20 feet was taken ; (2) to the west of Rudha Dubh-
beag, where soundings in 22 and 26 feet were taken ; and (3) in the
westernmost division, where soundings in 23, 25, and 29 feet (the maximum
depth recorded) were taken. The volume of water is estimated at 70
million cubic feet, and the mean depth at 6J feet. The area draining
directly into the loch is nearly 9 square miles, but as it receives the
overflow from Loch a' Bhaillidh, the total drainage area is about 38 J
square miles.

Temperature Observations. — Serial temperatures taken on May 19, 1903,

70 BATHYMETRICAL SURVEY OF

at the position of the deepest sounding, showed a range from surface to
bottom of 4° Fahr., as follows :—

Surface... 50° -0 Fahr.

10 feet 48°-0 „

20 „ 47°-5 „

28 „ 46°-0 „

Lochan Inlhir (see Plate XXVI.). — Lochan Inbhir lies about a mile to
the west of Lochan na Salach Uidhre, and is also irregular in outline, with
many islands and boulders. The length is about 1J miles, and the
maximum breadth one-third of a mile. The superficial area is about 145
acres, of which 81 per cent, is covered by less than 10 feet of water.
Soundings in depths of 10 feet and over were taken in four places : (1) near
the east end, where casts in 12 and 16 feet were made; (2) farther to the
north-west and close to the northern shore, where an isolated sounding in
10 feet was taken ; (3) in the central portion of the loch, where soundings
in 11, 13, and 14 feet were taken ; and (4) in the western portion of the
loch, where there is a large deep basin, one-third of a mile in length,
having a maximum depth of 50 feet, occupying a central position within
the basin. The volume of water is estimated at 50 million cubic feet, and
the mean depth at 8 feet. On the Ordnance Survey maps the elevation is
given as 992 feet above the sea, which makes it 30 feet lower than the
western division of Lochan na Salach Uidhre ; a drift-mark was observed
at the east end 7 feet above the level of the water. The drainage basin of
Lochan Inbhir is a very large one, including the drainage areas of the two
lochs further east, and amounting to 52 J square miles, or about 230 times
greater than the area of the loch.

Temperature Observations. — Serial temperatures taken in the deepest
part of the loch on May 20, 1903, gave the following results :—

Surface 49°-0 Fahr.

10 feet 49°-0 •„

20 „ 46°-0 „

25 „ 45°-7 „

50 „ 45°-0 „

The range of temperature from surface to bottom was 4°, there being a
fall of 3° between 10 and 20 feet, while the readings at the surface and at
10 feet were identical.

Loch JZilde Mbr (see Plate XXVII.).— Loch Eilde Mor (or Eilt-More)
is the largest loch within the basin, and is situated about 6 miles south-
east from Ben Nevis, high mountains towering on both sides of the loch,
culminating in Binnein Mor (3700 feet) and Sgor na h-Eilde (3279 feet)
on the north-west, and Glas Bheinn (2587 feet) on the east. Unlike the
other lochs in the basin, Loch Eilde Mor is regular in conformation, and
comparatively deep, trending north-east and south-west, and about 2 miles
in length, with a maximum breadth of a quarter of a mile. Its waters

THE FRESH- WATER LOCHS OF SCOTLAND.

71

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72 BATHYMETRIOAL SURVEY OF

cover an area of about 240 acres, and the area draining into it exceeds 6
square miles, including Lock Eilde Beag, lying a quarter of a mile to the
north-east, which was not surveyed. The maximum depth of 100 feet was
observed near the south-west end, about 150 yards from the north-western
shore. The volume of water is estimated at 493 millions of cubic feet, and
the mean depth at 47 feet. The loch was surveyed on May 13, 1903, the
elevation being approximately 1110 feet above the sea.

The contour-lines of depth coincide approximately with the outline of
the loch, but approach nearer to the north-western shore, off which the
slope is steepest. Near the north-east end there is a slight shoaling
covered by 70 feet of water, separating a sounding in 75 feet from the
main deep basin. The following table, giving the areas between the
contour-lines, and the percentages to the total area, indicates the general
regularity and somewhat flat-bottomed character of the basin : —

Feet. Acres. Per cent.

Oto25 65 ... 27-1

25 „ 50 ... 64 ... 26-6

50 „ 75 66 ... 27-5

Over 75 45 ... 18-8

240 100-0

The temperature of the surface water on the date of the survey was
47°*0 Fahr., but serials could not be attempted on account of a heavy gale.

From the table on p. 71 it will be seen that in the ten lochs under con-
sideration 570 soundings were taken, and that the aggregate area of the
water-surface is about 2J square miles, so that the average number of
soundings per square mile of surface is 228. The aggregate volume of
water contained in the lochs is estimated at 2067 millions of cubic feet.
The area drained by these lochs is 85J square miles, or 34 times the area
of the lochs.

THE FRESH-WATER LOCHS OF SCOTLAND. 73

LOCHS OF THE OBAN BASIN.

THE only loch to be dealt with here is the little Loch Gleann a' Bhearraidh,
lying about 2 miles to the south-south-west of Oban, from which the
town draws its water-supply. It is a good trout loch, but the fishing is
preserved.

Loch Gleann a' BJiearraidh (see Plate XXVIII.).— Loch Gleann a*
Bhearraidh (or na Gleann na Bheathrach) is a long narrow loch, trending
south-west and north-east, and about two-thirds of a mile in length, by one-
eighth of a mile in maximum breadth, covering an area of about 29 acres,
and draining an area of about half a square mile. The loch is cut into
two portions by the narrows near the upper (south-west) end, where the road
crosses the loch over a bridge. The upper portion beyond the bridge is
shallow, the greatest depth being 9 feet ; but the north-eastern portion is
almost entirely covered by more than 1 0 feet of water, and there is a deep
basin with a maximum depth of 48 feet near the lower end. The volume
of water is estimated at 16 million cubic feet, and the mean depth at 13
feet. The basin is simple, and of the whole area 89 per cent, is covered
by less than 20 feet of water, while 4 per cent, exceeds 40 feet in depth.
When the loch was surveyed on May 28, 1903, the elevation above the
sea could not be determined, but the water was standing up to the edge
of the overflow passage at the weir.

74

BATHYMETRICAL SURVEY OF

LOCHS OF THE FEOCHAN BASIN.

WITHIN the area draining into Loch Feochan, a branch of the Firth of
Lome, three lochs were sounded by the Lake Survey, viz. Lochs Nell,
Scamadale, and na Sreinge (see Index Map, Fig. 7). Loch Nell drains by

English Miles

Bartholomew.

z 3 s 6

FIG. 7. — INDEX MAP OP THE OBAN, FEOCHAN, SEIL, AND MELFORT BASINS.

THE FRESH- WATER LOCHS OF SCOTLAND. 75

the river Nell into the head of Loch Feochan, while the other two drain
by the river Enchar, entering on the southern side of the sea-loch at
Kilninver. Lochs Nell and Scamadale are important lochs, both exceeding
100 feet in depth, and the fishing in all the lochs is good, Loch na Sreinge
being referred to as one of the best fishing lochs in Lorn, though strictly
preserved, while Loch Scamadale contains salmon, sea-trout, and yellow
trout.

Loch Nell fsee Plate XXIX.).— Loch Nell is situated about 2 miles
south-east of Oban, and 1^ miles north-east of the head of Loch Feochan.
It may at one time have formed part of the sea-loch, being separated from
it by low, flat, alluvial ground. It is somewhat irregular in outline, with a
constriction near the middle, and trends in a north-east and south-west
direction, being nearly 2 miles in length, by over one-third of a mile
in maximum breadth. Its waters cover an area of about 321 acres, or half
a square mile, and the drainage area extends to about 14 square miles.
The north-eastern half of the loch is comparatively shallow, i.e. less than
50 feet in depth, but the south-western portion is deep, the maximum depth
of 115 feet having been recorded little more than half a mile from the
lower end. The volume of water is estimated at 515 million cubic feet,
and the mean depth at 37 feet. The loch was surveyed on May 27, 1903,
when the elevation was found to be 49*2 feet above the sea.

The river Lonan has laid down a considerable delta at the head of the
loch, as has also the Allt Cabrachan on the south-eastern shore, near the
upper extremity. The conformation of the basin is simple, the 25-feet
area being over a mile in length, and distant about half a mile from the
head of the loch, while the 50-feet area is three-quarters of a mile, and the
100-feet area nearly half a mile, in length. Of the entire lake-floor about
56 per cent, is covered by less than 25 feet of water.

Temperature Observations. — Serial temperatures taken in the deepest
part of the loch gave the following results : —

Surface... 61°-4 Fahr.

5 feet 54°-9

10 , 52°-7

25 ,, ... ... ... 49c-9

50 „ 49°-2

100 „ 48°-2

The range of temperature from surface to bottom amounted to 13?-2,
there being a fall of no less than 6°-5 between the surface and a depth
of 5 feet — a fall equal to 17'3 per foot of depth.

Loch na Sreinge (see Plate XXVIII.).— Loch na Sreinge (or String) is
situated about 2J miles to the south-east of Loch Scamadale, into which
it drains by the Allt Braglenmore, and about a mile north of Loch Avich
in the Etive basin. It is sub-triangular in outline, with the apex pointing
in a south-west direction, and a large island occupies a central position in

76 BATHYMETEICAL SURVEY OF

the loch. It is half a mile in length, with a maximum breadth of one-
third of a mile. The superficial area is about 50 acres, of which 63 per
cent, is covered by less than 20 feet of water, and the drainage area is
about 1 square mile. The maximum depth of 43 feet was observed off the
central part of the western shore. The volume of water is estimated at
43 million cubic feet, and the mean depth at 17J feet. The loch was
surveyed on May 27, 1903, when the elevation was found to be 777'6 feet
above the sea. The surface temperature was 63°*0 Fahr.

Loch Scamadale (see Plate XXIX.). — Loch Scamadale lies about 2J
miles from the head of Loch Feochan, and about 6 miles south-east from
Oban. The loch trends east and west, and is over 1J miles in length, the
maximum breadth being about one-third of a mile, and the mean breadth
less than a quarter of a mile. The superficial area exceeds one-third of a
square mile, or about 226 acres, while the total area draining into it is
nearly 13 J square miles, including that draining into Loch na Sreinge. The
maximum depth of 145 feet was recorded near the centre of the loch, the
mean depth being estimated at nearly 70 feet, and the volume of water
at 685 millions of cubic feet. The loch was surveyed on June 1, 1903,
when the elevation was found to be 221*0 feet above the sea, or 4 inches
lower than that observed by the officers of the Ordnance Survey on July 25,
1864, viz. 221-3 feet.

Tne conformation of the basin is simple, the slope along the southern
shore being much steeper than along the northern shore. The contour-
lines are deflected southward off the alluvial cone at the mouth of the
Eas Ruadh, on the northern shore, apparently as the result of the deposi-
tion of material brought down by that stream. The approximate areas
between the contour-lines drawn in at intervals of 50 feet, and the
percentages to the total area, are as follows : —

Feet. Acres. Per cent.

Oto 50 79 ... 35-1

50 „ 100 89 ... 39-4

Over 100 58 ... 25-5

226 100-0

This table shows the somewhat flat-bottomed character of the basin,
the zone covered by water between 50 and 100 feet in depth being larger
than the shore-zone covered by less than 50 feet of water.

Temperature Observations. — Serial temperatures, taken in the deepest
part of the loch, gave the following results :—

Surface 55°-0 Fahr.

20 feet 52°-l „

35 „ 47°'8 „

70 „ 46°-4 „

140 „ 46°-2 „

The range of temperature from surface to bottom amounted to 8°-8,
there being a fall of 2a-9 between the surface and a depth of 20 feet, and a
further fall of 4°-3 between the depths of 20 and 35 feet.

THE FRESH-WATER LOCHS OF SCOTLAND. 77

LOCHS OF THE SEIL BASIN.

LOCH Seil is the only loch draining into Seil sound which was sounded by
the Lake Survey.

•

Loch Seil (see Plate XXX.) lies little more than a mile south-west
from Kilninver, to the south of the entrance to Loch Feochan. It trends
north-north-east and south-south-west, and is two-thirds of a mile in
length, the maximum breadth being about one-sixth of a mile, and the
superficial area about 50 acres, while the area draining into it is about
three-quarters of a square mile. The loch is comparatively deep, the
maximum depth being 91 feet, and the mean depth 37 feet, the volume
of water being estimated at 79 million cubic feet. The basin is simple,
the sides sloping towards the centre, where the deepest water was found.
The loch was surveyed on June 3, 1903, when the elevation was found
to be 55' 1 feet above the sea; the Ordnance Survey officers determined
the elevation on July 25, 1898, as being 54'8 feet above sea-level.

Temperature Observations. — Serial temperatures taken in the deepest
part of the loch gave the following results : —

Surface 59°-0 Fahr.

10 feet 58°-8 „

15 „ 54°-l „

20 „ 52°-l „

40 „ - ... 50°-2 „

80 „ 48°-0 „

The range from surface to bottom was 11°, the greatest fall being
one of -t'-7 between the depths of 10 and 15 feet — a fall nearly equal
to 1D per foot of depth.

78 BATHYMETRICAL SURVEY OP

LOCHS OF THE MELFORT BASIN.

THE area draining into Loch Melfort "includes a complex series of lochs,
eight of which were sounded by the Lake Survey, viz. Lochs Tralaig,
Dubh-mor, a' Chaoruinn, a' Phearsain, nan Druimnean, an Losgainn Mor,
and Kilchoan (upper and lower). Loch Tralaig, the most important
one in the basin, drains by the river Oude into Fearnach bay, the north-
eastern offshoot at the head of Loch Melfort, while Lochs Dubh-mor, a'
Chaoruinn, a' Phearsain, nan Druimnean, and an Losgainn Mor drain
into Loch na Cille, the south-eastern offshoot at the head of Loch
Melfort ; the two Kilchoan lochs drain into Kilchoan bay on the northern
shore of Loch Melfort near its niouth. These lochs are fairly deep,
all but one exceeding 40 feet, and two of them exceeding 100 feet, in
depth. The scenery of the district is very fine, and the trout fishing
in the lochs is good, some of them having been stocked with Loch Leven
trout.

Loch Tralaig (see Plate XXXI.). — Loch Tralaig is situated about
3 miles north-east of Kilmelfort, and little more than 2 miles north-west
of Loch Avich in the Etive basin. It trends almost east and west, and
exceeds a mile in length, with a maximum breadth of one-third of a mile.
The loch covers an area of about 149 acres, or nearly a quarter of a square
mile, and receives the drainage from an area of about 4^ square miles.
The principal inflow is at the eastern end, while several minor streams
enter on the southern side; the river Oude flows out at the west end.
The volume of water is estimated at 267 millions of cubic feet, and the
mean depth at 41 feet. The conformation is rather complex, the loch
being divided into two basins, the larger and deeper one in the eastern
portion of the loch, separated by a narrow channel from the smaller ana
shallower one at the west end. The maximum depth of 117 feet was
observed in the centre of the eastern basin, while the deepest sounding
taken in the western basin was 53 feet, the depth on the intervening
barrier being 13 to 23 feet. Within the eastern basin there is in deep
water a slight shoaling covered by 74 feet, with deeper water both to the
west and to the east. The following table gives the approximate areas
between the contour-lines, and the percentages to the total area : —

THE FRESH- WATER LOCHS OF SCOTLAND. 79

Feet. ' Acres. Per cent.

Oto 25 57 ... 38-5

25 „ 50 39 ... 26-3

50 „ 75 33 ... 22-1 •

75 „ 100 ... 12 ... 8-1

Over 100 8 ... 5-0

149 100-0

The loch was surveyed on June tf, 1903, when the elevation was found
to be 420-0 feet above the sea; when visited by the Ordnance Survey
officers on August 31, 1804, the elevation was 422'9 feet above sea-level.

Temperature Observations.— Serial temperatures were taken in the
deepest part of the loch with the following results : —

Surface 60°O Fahr.

10 feet 59°-8 „

20 „ 55°-7 „

45 , 47°-8 „

90 „ 47°-0 „

These observations show a range of 13° from surface to bottom, there
being a fall of about 4 between 10 and 20 feet, and a further fall of about
8~ between 20 and 45 feet.

Loch Dubh-mbr (see Plate XXXI.). — Loch Dubh-mor is a small but
comparatively very deep loch situated less than a mile to the south-east
of Loch Tralaig, and little more than a mile to the north-west of Loch
Avich. The outline is sub-circular, though the shore-line is somewhat
irregular, the maximum diameter being about one- third of a mile. The
superficial area is about 30 acres, of which 54 per cent, is covered by less
than 50 feet of water, and 9 per cent, by more than 100 feet of water.
Near the north-eastern shore is a small deep area enclosing the maximum
depth of 114 feet, the shore-slope being steepest in this locality. The
volume of water is estimated at 66 million cubic feet, and the mean depth
at 51 feet. The elevation could not be determined by levelling, but is
apparently about 900 feet above the sea.

Temperature Observations. — Serial temperatures taken on June 5, 1903,
in the deepest part of the loch gave the following results :—

Surface 57°-4 Fahr.

10 feet 57°-0

15 , 54°-6

20 49°-2

25 „ 47°-8

50 , 46°-0

100 „ .' 44°-7

These readings are all lower than those taken at sim lar depths in
the larger Loch Tralaig on the following day, the difference at the depth
of 20 feet, for instance, being as much as 67'5- The range shown by
these observations is 12 -7, the most rapid fall being recorded between

80 BATHYMETRICAL SURVEY OF

15 and 20 feet — a fall of 5°'4 in the 5 feet of water, or more than 1° per
foot of depth.

Loch a' Ghaoruinn (see Plate XXXI.) is a small shallow loch, lying over
half a mile to the south-west of Loch Dnbh-mor ; weeds are abundant, and
the bottom is covered by a peaty mud. The loch is irregular in outline,
trending east and west, and one-third of a mile in length, with a maximum
breadth across the middle of one-seventh of a mile. The area is about
18 acres, of which 60 per cent, is covered by less than 10 feet of water.
The eastern portion is shallow, the deeper water lying in the western half,
two soundings at the maximum depth of 20 feet being recorded, one in
a central position, and the other near the west end. The volume is
estimated at 7 million cubic feet, and the mean depth at 9^ feet. The
elevation could not be determined, but is apparently about 860 feet above
the sea. On June 5, 1903, the surface temperature was 59°'2 Fahr.

Loch a' Phearsain (see Plate XXXL). — Loch a' Phearsain (variously
spelt Phearson, Pearsan, or Fearsan, or Parson's Loch) is situated close to
Kilmelfort, at the head of Loch Melfort, and is nearly rectangular in
outline, with a slight curve in the eastern shore-line, which causes a
narrowing near the middle, where a shallow ridge crosses the loch. It
trends almost north and south, and is nearly half a mile in length, with a
maximum breadth of a quarter of a mile. The central ridge divides
the loch into two basins, the maximum depth of 53 feet being found
in the southern basin towards the eastern shore, the maximum depth
in the northern basin being 41 feet. The superficial area is about 61 acres,
of which about 36 per cent, is covered by less than 10 feet of water, while
10 per cent, is covered by more than 40 feet of water, the mean depth
being 19 J feet. The loch lies in a rock-basin, and contains about
52 million cubic feet of water, the area draining into it being about 3J
square miles. The loch was surveyed on May 30, 1903, when the eleva-
tion was found to be 226-0 feet above the sea. The temperature of the
surface water was 60°'2 Fahr.

Loch nan Druimnean (see Plate XXXI.).— Loch nan Druimnean (or
Drimnin) is situated near the head of Loch Melfort, less than half a
mile to the west of Loch a' Phearsain. It is a narrow loch, trending
nearly north and south, and exceeding half a mile in length, its waters
covering an area of about 37^ acres. The maximum depth of 59 feet was
observed near the middle of the loch. The volume of water is estimated
at 26 million cubic feet, and the mean depth at 15^ feet. The loch was
surveyed on May 30, 1903, when the elevation was 169*3 feet above the
sea ; when visited by the Ordnance Survey officers on October 5, 1864, the
elevation was 170'1 feet above sea- level. A shallow ridge crosses the loch
towards the northern end, dividing it into two deep basins, the smaller
basin at the north end having a maximum depth of 30 feet, while the

THE FRESH- WATER LOCHS OF SCOTLAND. 81

larger and deeper basin occupies the wide southern portion of the loch ;
the slope off the eastern shore is in places very steep. The surface
temperature was 63^0 Fahr.

Loch an Losgainn Mbr (see Plate XXXI.) is an irregular loch situated
about a mile south-east of Loch a' Phearsain, trending nearly east and
west, and exceeding half a mile in length. The loch lies in a rock-basin,
and covers an area of about 33 acres, the volume being estimated at
27 million cubic feet. It was surveyed on May 29, 1903, when the
elevation was 508-4 feet above the sea, which differs little from the eleva-
tion determined by the Ordnance Survey on October 4, 1864, viz. 508-6 feet.
A prominent peninsula projecting from the southern shore cuts the loch
into two unequal basins, the smaller to the east of the peninsula having a
maximum depth of 29 feet, the larger occupying the wide portion of the
loch to the west of the peninsula, and having a maximum depth of 51 feet.
Of the entire lake-floor, about 68 per cent, is covered by less than 25 feet
of water.

Temperature Observations. — Serial temperatures taken in the deepest
part gave the following results :—

Surface.., 60°-4 Fahr.

10 feet 58°-0 „

20 „ 54°-8 „

40 „ 49°-5 „

These observations show a range of about 11° from surface to bottom,
the fall of temperature being tolerably uniform.

Kilchoan Lochs (see Plate XXX.). — Two small lochs trending in a
north and south direction, and situated in close jyoximity about half a mile
from the northern shore of Loch Melfort, are known as theKilchoan Lochs.
Both lie in rocky basins, and are separated by a ridge of rock, the difference
in level being about 42 feet.

Upper Kilchoan Loch is the larger and deeper of the two, and is about
one-third of a mile in length, covering an area of about 23 acres. The
maximum depth of 70 feet was found rather nearer the northern than the
southern end. The volume of water is estimated at 29 million cubic feet,
and the mean depth at 29^ feet. The basin is simple, and the contour-
lines coincide approximately with the outline of the loch, about half the
lake-floor being covered by less than 25 feet of water. The loch was
surveyed on June 2, 1903, the elevation being approximately 378 feet
above the sea.

Lower Kilchoan Loch is rather longer than the upper one, while the
breadth is nearly uniform throughout, and equal to about one-twelfth of a
mile, or 150 yards. It is fairly deep, the maximum depth being 45 feet,
and the mean depth 20 feet, the volume of water being estimated at
16 million cubic feet. The superficial area is about 18 acres, of which

82

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THE FRESH-WATER LOCHS OP SCOTLAND. 83

about 65 per cent, is covered by less than 25 feet of water. The con-
formation is simple, two soundings at the maximum depth of 45 feet
being recorded near the middle of the loch. The loch was surveyed on the
same day as the upper loch, the elevation being approximately 336 feet
above the sea. The surface temperature was 56°'8 Fahr.

From the opposite table it will be seen that in the thirteen lochs under
consideration 855 soundings were taken, and that the aggregate area of the
water-surface is 1*60 square miles, so that the average number of soundings
per square mile of surface is 515. The aggregate volume of water con-
tained in the lochs is estimated at 1828 millions of cubic feet. The
area drained by these lochs is about 34 square miles, or 20 J times the area
of the lochs.

84 BATHYMETRICAL SURVEY OF

THE LOCHS OF BUTE.

THE principal lochs on the island of Bute (see Index Map, Fig. 8) are
situated close together in the southern half of the island, close to the
county town of Rothesay. They are all narrow and elongate, with their
axes running parallel from south-south-west to north-north-east. Owing
to lack of boats only Loch Fad and the Kirk Dam were surveyed. Loch
Ascog, a mile in length, and half a mile east of Loch Fad, is used as
the water supply of Rothesay.

Loch Fad (see Plate XXXII.).— Loch Fad lies immediately south
of the town of Rothesay, from which it is about a mile distant. -It lies
between dense woods on the west and cultivated land on the east. The
greater part of the west shore is formed by a range of low crags, but the
north end is gravelly. The east shore is also gravelly in the northern
part, but from the rocky wooded knoll of Bardarroch wood southward
rock is exposed at many places.

The length is nearly 2 miles, and the greatest breadth, at the south
end, a quarter of a mile. It is a simple basin of very uniform contour
and of very moderate depth, with steep sides, nearly flat bottom, and the
central depth varying but little from end to end. The loch is greatly
narrowed in the middle, but is not reduced in depth there. The maximum
depth of 38 feet is a little south of the narrows. There is a terrace
laid down by the Barnauld burn. The mean depth is 17 feet, the area
rather more than a quarter of a square mile, or about 176 acres, and the
volume 232 millions of cubic feet.

The drainage area exceeds 2 square miles. The only important in-
flowing stream is the Barnauld burn. The outflow is by the channel,
in length merely the width of the road, leading to the Kirk Dam. When
surveyed on August 21, 1906, the surface was 34'5 feet above sea-level,
nearly identical with the elevation determined by the Ordnance Survey
on June 10, 1896, viz. 34-3 feet.

The temperature varied only 0°'2 Fahr. between the surface (60°-5)
and a depth of 26 feet ^60°'3).

Kirk Dam (see Plate XXXII.).— The Kirk Dam is the northern
portion of Loch Fad, and lies close to the town of Rothesay. It is
separated from Loch Fad by an embankment, but communicates freely

THE FRESH-WATER LOCHS OP SCOTLAND.

85

with it, and at the date of the survey was at the same level. It lies
amid fields, with some boggy moorland on the west side, and some points
of rock exposed in the narrow part.

An&ca/psieP*

SOUND or B U T £

, English Miles

o i a 3

FIG. 8. — INDEX MAP OF THE ISLAND OF BUTE..

86 BATHYMETRICAL SURVEY OF

It is three-quarters of a mile long, narrow in the middle, and expanded
towards each end to one-sixth of a mile. The bottom is absolutely flat, as
indicated by the invariable soundings, the maximum and the mean depth
alike 5 feet. The area is about 54 acres, and the volume 12 millions of
cubic feet. It is dammed at the north end, and communicates with the sea
by a mill lade. The drainage area, including Loch Fad, is fully 3 square
miles.

The temperature was 62°*0 Fahr. throughout, nearly 2° higher than
Loch Fad.

THE FRESH-WATER LOCHS OF SCOTLAND. 87

LOCHS OF THE EACHAIG BASIN.

THE only loch within this basin (see Index Map, Fig. 9) is Loch Eck,
which drains by the river Eachaig into the Holy loch, an arm of the
Clyde estuary, and is one of the best-known in the western Highlands, the
coach-road from Dunoon to Strachur running along its eastern shore, and
carrying numerous tourists during the season. The head of the loch
is distant about 4 miles from the shores of Loch Fyne at Strachur, while
the foot of the loch is distant about 3 miles from the head of the Holy loch.
The scenery of the district is very fine, most of the hills on both sides
of the loch exceeding 1000 feet, and some of them exceeding 2000 feet, in
height, culminating in Beinn Bheula (2527 feet) at the north end of the
loch, and Beinn Mhor (2433 feet) to the west of the lower portion of the
loch. The fishing in the loch includes salmon and sea-trout, as well
as loch-trout.

Loch Eck (see Plate XXXIII.).— Loch Eck partakes of the elongate
character of many Highland lochs, trending nearly north and south on the
whole, but with a curve in the outline towards the upper end, which causes
the extreme northern portion to trend in a north-west direction. It is
6 miles in length, with a maximum breadth of over one-third of a mile,
the mean breadth being about a quarter of a mile. The superficial area is
about If square miles, while the area draining into the loch is nearly
40 square miles. The shore-line is sinuous, while numerous streams have
cut their way into the sides of the mountains, and empty themselves into
the loch on both sides. The principal inflowing stream is the river Cur,
which enters at the upper end, draiuing with its tributaries the mountain-
slopes at the head of the basin. The loch is fairly deep, the maximum
depth observed being 139 feet, while the mean depth exceeds 50 feet, the
volume of water being estimated at 2381 millions of cubic feet. The
25-feet contour is continuous from end to end of the loch, but the 50-feet
basin is divided into two portions by a slight shoaling just south of the
narrows at Coirantee, the deepest sounding on the shoaling being 46 feet.
The 75-feet contour is cut up into four portions : the largest and deepest
is nearly 2 miles in length, and is distant little more than half a mile from
the upper extremity ; the others are of small extent, one close to the
northern end, based on a sounding in 79 feet; a second about Ij miles
from the southern end, based on soundings in 75 and 81 feet; and a third

8S

BATHYMETMCAL SURVEY OF

•English Milee,

Bart/,o/or::<:nft/m'

FIG. 9. — INDEX MAP OF THE EACHAIG BASIN.

THE FRESH-WAT£R LOCHS OF SCOTLAND.

89

about half a mile from the southern end, based on soundings in 82 and
83 feet. Within the largest 75-feet basin, and about 1J miles from
the northern end, is the 100-feet basin, about half a mile in length,
enclosing the maximum depth of the loch. The areas between the contour-
lines at intervals of 50 feet, and the percentages to the total area, are
as follows : —

Feet. Acres. Per cent.

Oto 50 571 ... 52-3

50 „ 100 485 ... 44-6

Over 100 34 ... 3-1

1090 100-0

Loch Eck was surveyed on June 20-22, 1903, when the elevation was
found to be 66'6 feet above the sea, which agrees closely with the elevation
determined by the Ordnance Survey officers on June 9, 1863, viz. 06*8 feet.
Temperature Observations. — Two serial temperatures were taken on
June 22, 1903, one at 2.30 p.m., in the deepest part of the loch, in 135 feet
of water, and the other at noon, about a quarter of a mile to the south,
in 74 feet of water, with the following results : —

Deepest basin,
135 feet.

South of deepest
basin, 74 feet.

Surface

60°'0

58°-4

20 feet

58°-9

57°-5

27i

54°-9

35

52°-0

56°-3

42i

51°-5

502

50°-0

50°-2

70

48°-3

100

470.3

130

46°-5

—

The series in the deepest basin shows a range from surface to bottom
of 13°*5, the greatest fall being one of 4° between 20 and 27 J feet. The
shallower series shows a range of W'-l in the 70 feet of water, the greatest
fall being one of 43-8 between 35 and 42^ feet The " sprungschicht "
was thus observed nearer the surface in the deepest basin, the temperature
at a depth of 35 feet being 4°'3 lower than at the same depth in the
shallower water to the south, while at 50 feet the temperature was
practically the same in both series. A strong south-east wind was blowing
at the time these observations were taken, which might explain the higher
readings at the surface and at 20 feet in the more northerly position.

From the following table it will be seen that in the three lochs under
consideration 372 soundings were taken, and that the aggregate area of the
water-surface is just over 2 square miles, so that the average number of
soundings per square mile of surface is 180. The aggregate volume of
water contained in the lochs is estimated at 2525 millions of cubic feet.
The area drained by these lochs is nearly 43 square miles, or 21 times
the area of the lochs.

90

BATHYMETRICAL SURVEY OF

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THE FRESH-WATER LOCHS OF SCOTLAND. 91

LOCHS OF THE BOON BASIN.

THE river Boon, rising among the highest mountains of the south of
Scotland, drains a considerable mountain mass in the counties of Ayr and
Kirkcudbright. The elevated southern portion of the valley of the Boon
includes a number of lochs of moderate size, and Loch Boon, the greatest
lake of the south of Scotland. There are some small lochs in the lowland
part of the valley. Six of the lochs in the basin were surveyed. Lochs
Regar and Macaterick, the largest in the basin after Loch Boon, Loch
Enoch, a beautiful loch lying at a great elevation on the east side of the
Merrick, and a number of smaller lochs, could not be surveyed. The
superficial areas of the six lochs surveyed added together give a total area
of 2-6 square miles; their combined volumes amount to 1648 millions of
cubic feet, and together they drain nearly 60 square miles of country.

After leaving the mountains near Balmellington, the river Boon flows
for some 15 miles through fertile lowlands, and enters the Firth of Clyde
2 miles to the south of the town of Ayr (see Index Map, Fig. 10).

Locli Doon (see Plate XXXIV.). — This large and beautiful loch is
situated on the borders of the counties of Ayr and Kirkcudbright, about
1 5 miles south-east of the town of Ayr. It lies amid hills, which increase
in height towards the head of the loch till an elevation of 2000 feet is
reached on the east side ; while to the south the Galloway highlands rise,
peak above peak, culminating in the Merrick (2764 feet) and Corserine
(2608 feet). The hills of the upper part of the glen are rugged and dark ;
the lower end is wooded. Here the river, immediately on issuing from
the loch, rushes as a torrent through Ness Gleo, a glen of unrivalled
beauty. There is much smooth, polished rock exposed on the shores, and
in the form of whale -backed islands.

The valley occupied by the loch runs north and south, but the axis
of the loch is strongly curved. In form, Loch Boon is narrow and elongate,
like the majority of the highland lochs. It measures 5 miles in length,
in a straight line between the ends, nearly 0 miles following the central
line. The greatest breadth, at the Ford of Moak, about 2 miles from the
lower end, is over 1^ miles, and the mean breadth is one-third of a mile.
The maximum depth, l.V miles from the head of the loch, is K>n feet, and
the mean depth 27 feet. The superficial area is 2 square miles, and the
volume of water 1517 millions of cubic feet. The area drained amounts

92

BATHYMETRICAL SUKVEY OF

to 50J square miles, and includes many lochs (Regar, Macaterick, Finlas,
Muck, Derclach, Enoch, etc.). There are many large feeders : Gala Lane
at the head of the loch, Carrick Lane from Lochs Regar and Macaterick,
Garpel burn from Lochs Finlas and Derclach on the west, and the Muck
burn from Loch Muck on the east. The outflow by the river Boon, now
controlled by a dam and sluice, is through a rocky channel, on the east
side of which rise high cliffs.

English Milea

0 I E 3 4 8 10 16

FIG. 10. — INDEX MAP OF THE BOON, GIRVAN, AND STINCHAB BASINS.

The basin of Loch Doon is very irregular. The 25-feet contour,
though continuous nearly from end to end of the loch, is much interfered
with by groups of islands and shoals, and there are two separate basins
over 50 feet in depth. The southern and narrower portion of the loch,
running between high hills, is deepest. Here the 50-feet area is 1J miles
long, the 75-feet area half a mile long, and a very small area, founded on
a single sounding, reaches 100 feet in depth. Northward the loch shallows
to 28 feet, and deepens again to the second area of over 50 feet, which is

THE FRESH-WATER LOCHS OF SCOTLAND. 93

nearly in the broadest part. It is of small extent (a quarter of a mile
long), and has a greatest depth of 58 feet. At the date of the eurvey
(July 10 and 11, 1903) the surface was 673'3 feet above sea-level. This
was considerably higher than when surveyed by the Ordnance Survey
(though the elevation is not given on the 6-inch maps), and the outline
of the loch, especially in the southern portion, was greatly altered in
consequence.

A series of temperatures taken near the deepest part of the loch showed
a range of 4°*6 Fahr., as shown in the following table : —

Surface... 59°'6 Fahr.

10 feet 58°-9 „

25 „ 58°-0 „

50 „ 56°-8 „

80 „ 55°-0 „

Derclach Loch (see Plate XXXV.). — A very small, narrow, and shallow
loch, lying close to the west of Loch Finlas. It is a little over half a mile
long, one-eighth of a mile broad, and 12 feet deep. The bottom at the
deeper part is flat, and 10 feet deep over a considerable area. The
maximum of 12 feet is close to the west end; the eastern part is very
narrow, irregular, and from 1 to 6 feet deep. The mean depth is 7J feet,
the area 38 acres, and the volume 12 millions of cubic feet. The area
drained is scarcely a square mile. No important stream enters, and the
burn flowing east to Loch Finlas is only about 100 yards long. The
shores are of peat and gravel, with rock exposed at several points.
The surface was 837'1 5 feet above sea-level on July 13, 1903. The
temperature was 58°*4 Fahr. throughout.

Loch Finla* (see Plate XXXV.).— A small, narrow, dumb-bell-shaped
loch, with a straight axis running north-west to south-east, lying among
moorland, 1J miles to the west of Loch Boon. The hills on the north
rise to a little over 1000 feet (200 feet above the loch) ; on the south they
are higher, Craiglee attaining a height of 1716 feet. The loch is 1J miles
long and one-third of a mile broad in the north-western expansion. The
channel connecting the ends of the loch is three-quarters of a mile long,
for the most part less than 100 yards broad, and varies in depth from
6 to 18 feet in the centre. The north-western expansion is the deeper.
The bottom is irregular, with the maximum depth of 40 feet in the centre,
but other soundings up to 34 feet close inshore. The south-eastern ex-
pansion is much shallower, and nearly flat-bottomed, with a depth of about
10 feet, and a little depression of 26 feet at the end of the strait. The
mean depth is nearly 10 feet, the area about 138 acres, and the volume of
water 58 millions of cubic feet. The area drained is nearly 5 square miles.
The natural outflow is by the Garpel burn, issuing from the east end of
the loch ; but the water is now utilized as the water supply for the town
of Ayr. The surface was 829'65 feet above sea-level on July 13, 1903.

94 BATHYMETRICAL SURVEY OF

Temperatures taken in the deepest part showed a range of less than
2° Fahr. :—

Surface 58°-2 Fahr.

10 feet 58°-2

20 „ '. 58°-0

25 „ ... 57°'7

30 „ 57°-0

40 „ 56°-3

Loch Muck (see Plate XXXVI.).— A small loch, shaped like the
letter L, lying about a mile east of Loch Doon, with which it is connected
by the Muck burn, entering the head of the bay called the Ford of Moak.
It is barely half a mile long and one-fifth of a mile broad at the southern
end. There is a slight constriction in the middle, where the depth is
only 7 feet. North of this is a slight depression, with a depth of 10 feet ;
to the south is a deeper basin, with the maximum depth of 22 feet. The
mean depth is 7 feet, the area about 28 acres, and the volume 9 millions of
cubic feet. The area drained is about 1J square miles. The Polnaskie
burn enters just "where the Muck burn flows out southwards. The surface
was 992-4 feet above the sea on July 20, 1903.

Temperatures in the deepest part gave —

Surface 58°-2 Fahr.

5 feet 57°-4 „

10 „ 56°-4 „

20 „ 56°-3 „

Bogton Loch (see Plate XXXVI.).— This is simply a shallow, weedy
expansion of the river Doon, 2 miles north-west of the outflow from Loch
Doon. It is two-thirds of a mile long, a quarter of a mile broad, and
4 feet in greatest depth. The bottom is flat, and nearly everywhere covered
by 3 feet of water. The mean depth is 2 feet, the area 60 acres, and the
volume 5 millions of cubic feet. The area drained, including Loch Doon,
etc., amounts to 60 square miles. The surface was 522*6 feet above sea-
level on July 13, 1903, or more than 150 feet lower than Loch Doon,
showing the very rapid fall in the intervening 2 miles.

The surface temperature at the north-west end was 56°' 6 Fahr., at the
south end 57°-5.

Martnaham Loch (see Plate XXXVI.). — A narrow loch, lying 5 miles
south-east of the town of Ayr. The shores are partly wooded, partly
smooth fields. Nearly midway between the ends the ruins of Martnaham
Castle stand on an island, connected with the south shore by a causeway.
The shores of the western basin are fringed with reeds. The axis of the
loch runs north-east to south-west. The length is 1± miles, and the
greatest breadth, in the middle of the loch, where a deep bay runs to
the north-west, is a quarter of a mile.

There are three small basins, the western one being the deepest, with

THE FRESH-WATER LOCHS OF SCOTLAND. 95

the maximum of 29 feet, the central one 22 feet, and the eastern one
16 feet. In the channel at the castle the depth is only 5 feet. The
mean depth is nearly 10 feet, the area about 113 acres, and the volume
47 millions of cubic feet. The drainage area measures 3f square miles.
The Sandhill burn flows in at the north-east corner of the loch. The
outflow, at the south-west corner, has been dammed up by a bank of
stones in order to supply a mill lade; but there is no sluice, and the
overflow is divided between the two streams. The surface was 268*8 feet
above sea-level on November 6, 1906.

The temperature at the surface was 45°'5 Fahr., and at 25 feet 45°'3.

96 BATHYMETRICAL SURVEY OF

LOCHS OF THE GIKVAN BASIN.

THE river Girvan, or water of Girvan, which has its entire course in the
county of Ayr, originates in a tiny lochan, called Loch Girvan Eye, on the
northern elope of Shalloch on Minnoch, a hill 2520 feet in height, near
the county border. For some 10 miles from its source it runs from south-
east to north-west, parallel to, and very near, the river Doon, passing
through a number of small lochs, the chief of which is Loch Bradan, then
at the village of Kirkmichael it turns at right angles and flows south-west-
ward to the sea at Girvan. Three lochs near the source of the river were
surveyed, Loch Bradan, of fair size, the other two (Loch Lure and Cornish
Loch) very small. The three lochs have a combined area of nearly one-
fifth of a square mile, a volume of 24 millions of cubic feet, and drainage
area of 5J square miles.

Cornish Loch (see Plate XXXVII.). — A very small loch lying at an
elevation of 1303-7 feet above the sea, near the source of the river Girvan.
Eugged rocky and heather-clad hills surround the loch, rising more steeply
on the north side. The promontories round the shore are of rock. On the
south side, where two large streams enter, one of them the water of Girvan,
there is a broad boggy flat, liable to floods. The length, from east to west,
is a quarter of a mile, and the greatest breadth one-seventh of a mile. The
loch is shallow and the bottom nearly flat, with a greatest depth of 7 feet,
and a mean depth of 4 feet. The area is about 15 acres, and the volume
3 millions of cubic feet. The area drained is fully a square mile. The
water of Girvan flows northward from the west end of the loch.

The surface temperature on November 1, 1906, was 42°- 5 Fahr.

Loch Lure (see Plate XXXVII.). — A very small loch, immediately
west of T>"*h Bradan. It lies among rough moorland, and on the south
rises a rugged and sparsely wooded hill. The length is over one-third of a
mile, and the greatest breadth one-seventh of a mile. It is flat-bottomed
and shallow, the maximum depth 7 feet and the mean depth 4 feet. A
large area at the west end is filled with reeds and floatiDg plants. The area
is about 29 acres, and the volume 5 millions of cubic feet. The drainage
area, including Cornish Loch, is nearly 4 square miles. The water of
Girvan flows in at the west end, and out at the east, as a broad short
stream flowing around numerous islands to Loch Bradan. The height of

THE FRESH- WATER LOCHS OF SCOTLAND. 97

the surface above sea-level could not be determined. It was at the time of
the survey (November 2, 1906) 2 feet higher than Loch Bradan, which
was estimated to be 990 feet above sea-level.

The surface temperature was 43°-0 Fahr., or 1^° less than that of Loch
Bradan on the previous day.

Loch Brndan (see Plate XXXVII.).— A small loch, situated high up
among the hills, 4 miles west of Loch Boon. The rough moorland
surrounding the loch rises more steeply on the south. The shores are
stony, with a few exposures of rock. The length is nearly one mile, and
the maximum breadth, in the middle of the length, a quarter of a mile.
The bottom is nearly flat, with a maximum depth of 8 feet, and a mean
depth of 4^ feet. Many banks of stones and single boulders project above
the surface. The area is about 82 acres, and the volume 16 millions of
cubic feet. The drainage area is about oj square miles, and includes
Lochs Cornish and Lure. The water of Girvan enters at the west end of
the loch, and flows out northward from the north-east corner. Two other
large burns enter on the south side, one of them comiDg from Loch
Brecbowie.

No bench-mark could be found near the loch. The level was estimated
at about 990 feet above the sea on November 1, 1906.

The temperature was 44 '5 Fahr. throughout.

98 BATHYMETRICAL SURVEY OP

LOCHS OF THE STINCHAR BASIN.

THE river Stinchar, rising on Shalloch hill, about a mile west of the
source of the Girvan, runs its whole course roughly parallel to that river,
and entirely within the county of Ayr, entering the Firth of Clyde a few
miles further south, at Ballantrae. There are only a few insignificant
lochs in the basin. The largest, Loch Linfern, near the source of the
river, could not be surveyed. The only loch surveyed, Drumlamford Loch,
is near the Wigtownshire border, on a tributary of the Stinchar, the
I)uisk burn.

Drumlamford Loch (see Plate XXXVII.). — A small round loch in
southern Ayrshire, 4 miles south-east of Barrhill station, amid moor and
partly cultivated land. Shore of peat and stones. It measures a quarter
of a mile in greatest diameter. A large island, on which are some trees,
divides the loch into two parts, the connecting channels being mere
ditches. The larger eastern portion has a depth of 26 feet, the very small
western portion a depth of 23 feet. The mean depth is 11 feet, the area
about 28 acres, and the volume of water 13 millions of cubic feet. The
outflow is by a ditch, leading by the Lavery burn and the Duisk burn into
the river Stinchar. The water is raised by a windmill, and supplies
Drumlamford house.

The surface level is estimated at rather less than 450 feet above the
sea.

THE FRESH-WATER LOCHS OF SCOTLAND.

99

LOCHS OF THE RYAN BASIN.

THE area draining into Loch Ryan (see Index Map, Fig. 11) includes
only two lochs that were sounded by the Lake Survey : the Black Loch and
the White Loch of Inch, both considerable sheets of water, situated in the
grounds of Lochinch Castle ; their overflow is carried by the Messan burn,

Port. Pot

English Miles
' ' ' ' J> fc

Bartholomew

FIG. 11. — INDEX MAP OF THE BYAN, GALDENOCH, LUCE, AND BLADENOCH BASINS.

a stream about 2 miles long, into Loch Ryan, 2 miles north-east of the town
of Stranraer. They are both at the same level, being connected by a broad
canal. Their axes run parallel to one another, from south-east to north-
west. Their combined areas amount to half a square mile, their volumes
to 241 millions of cubic feet, and they drain an area of 6 square miles.

100 BATHYMETKICAL SURVEY OF

White Loch (see Plate XXXVIII.).— The White Loch (or Loch of Inch)
is the upper and shorter loch, but is broader than the Black Loch. It is of
oblong form, nearly a mile long, and a little less than half a mile in greatest
breadth. There are two basins of over 20 feet in depth — the northern
and deeper has the maximum of 38 feet near the east shore — the southern
with the greatest depth of 24 feet close to the south-east shore. Between
these basins, in the centre of the loch opposite Inch island, the depth is
15 feet. The mean depth is 14 feet, the area about 149 acres, or a quarter
of a square mile, and the volume 92 millions of cubic feet. The drainage
area is about a square mile. No streams enter, and the outflow is by the
canal connecting the two lochs. The loch was surveyed on August 19,
1903, when the elevation was found to be the same as the Black Loch,
53'95 feet above the sea; the elevation as determined by the Ordnance
Survey on July 26, 1893, was 53'0 feet.

The temperatures were —

Surface 62°-3 Fahr.

10 feet 62°-0 ,,

20 „ 60°-7 „

35 „ 60°-2 „

Black Loch (see Plate XXXVIII.).— The Black Loch (or Loch Crindil)
is considerably over a mile long, by one-third of a mile in greatest breadth.
In form it is narrowly triangular, broadest towards the south. The loch is
divided into two basins of over 25 feet in depth by a bank, on which the
depth is only 18 feet, opposite the mouth of the Sheuchan burn. The
larger basin is the southern one, where the maximum depth of 50 feet
occurs between the Heron isle and the east shore. The northern basin has
a depth of 34 feet. A very small elliptical area at the north is nearly cut
off from the main loch. In this is a depth of 27 feet. The mean depth is
over 23 feet, the area 146 acres, or nearly a quarter of a square mile, and
the volume of water 149 millions of cubic feet. The drainage area,
including the White Loch, measures nearly 6 square miles. The feeders
are the canal from the White Loch, and the Sheuchan burn. The Messan
burn flows out to the north-west. The loch was surveyed on the same
day as the White Loch, and was found to be at the same level, 53'95
feet above the sea ; the elevation as determined by the Ordnance Survey
on July 7, 1893, was 52'7 feet, the water having recently been raised
one foot.

The temperatures were —

Surface 62°-5 Fahr.

10 feet 61°-0 „

20 „ 60°-3 „

30 „ 60°-0 „

40 „ 60°-0 „

50 , 60°-0

THE FRESH-WATER LOCHS OF SCOTLAND. 101

LOCHS OF THE GALDENOCH BASIN.

A VERY small basin on the west coast of Wigtownshire, having only one
small, shallow, and apparently artificial, loch (Lochnaw), within the
grounds of Lochnaw Castle. The Galdenoch has a course of about three
miles in length, flowing from Lochnaw westward to the North Channel.

Lochnaw (see Plate XXXIX.). — A small and nearly round loch, entirely
surrounded by trees, 4 miles to the west of the town of Stranraer. It is
barely half a mile in length, and one-third of a mile broad. There are
several small, stony islands. The bottom is flat, and over the greater part
of the loch the depth is 5 or 6 feet. The mean depth is 4 feet, the area
about 47 acres, and the volume of water 9 millions of cubic feet. The
outflow is by a small burn, with a stony channel, running westward. The
area drained is a quarter of a square mile. The surface, on August 22,
1903, was 255-3 feet above sea-level, a little higher than the elevation
determined by the Ordnance Survey, on April 11, 1893, viz. 255'1 feet.

The temperature of the water was 61°'0 Fahr.

From the following table it will be seen that in the thirteen lochs
under consideration, 1028 soundings were taken, and that the aggregate
area of the water-surface is nearly 3^ square miles, so that the average
number of soundings per square mile of surface is 302. The aggregate
volume of water contained in the lochs is estimated at 1935 millions of
cubic feet. The area drained by these lochs is over 75 square miles,
or 22 times the area of the lochs.

102

BATHYMETRICAL SURVEY OF

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THE FRESH-WATER LOCHS OF SCOTLAND. 103

LOCHS OF THE LUCE BASIN.

THE area draining into Luce bay, on the south coast of Scotland, in-
cludes seven lochs which were sounded by the Lake Survey, viz. Lochs
Magillie, Soulseat, Cults, Ree, Whitefield, Eldrig, and White Loch of
Myrton. The three first-mentioned lochs drain by the Pitlanton burn into
the head of Luce bay near Glenluce, while Loch Ree lies farther to the
north, near the eastern shore of Loch Ryan, and drains by the Penwherran
burn into the water of Luce, the three last-mentioned lochs draining, each
by an independent stream, into Luce bay on its eastern side.

Loch Magillie (see Plate XXXIX.). — A very small oblong loch, situated
150 yards to the north of Soulseat Loch. It is surrounded by fields, and
has stony shores. It is nearly a quarter of a mile long and one-tenth of a
mile broad. The greater part of the bottom is covered by 7 feet of water,
or less, deepening slightly towards the east shore, close to which is the
maximum depth of 14 feet. The mean depth is over 5 feet, the area
about 12 acres, and the volume 3 millions of cubic feet. The drainage
area is about one-third of a square mile. There is no apparent outflow,
but the water is supposed to percolate through the gravel to Loch
Soulseat. When surveyed on August 21, 1903, the surface was 4J feet
above Loch Soulseat, or 43'7 feet above sea-level. The temperature at the
surface was 61°-2 Fahr., and at 10 feet 61°'0.

Loch Soulseat (see Plate XXXIX.).— Soulseat Loch lies half a mile
south-west of Castle Kennedy station on the Portpatrick and Wigtownshire
railway. It is surrounded by fields, and in form is irregular, being
divided into two portions by a wooded promontory, on which are the ruins
of Soulseat abbey. The length is over half a mile, and the greatest
breadth over a quarter of a mile. The constriction at the promontory is
16 feet deep, the basin on the north has the maximum depth of 42 feet
near the north shore, while the southern basin is shallower, with a depth
of 30 feet near the east shore. The mean depth is over 15 feet, the area
71 acres, and the volume 47 millions of cubic feet. The drainage area,
including Loch Magillie, is 1^ square miles. The Soulseat burn flows
south about 2 miles into the Pitlanton burn. The surface, on August 20,
1903, was 39-1 feet above sea-level, nearly identical with the elevation
determined by the Ordnance Survey on June 8, 1893, viz. 39-0 feet. The

104 BATHYMETHICAL SURVEY OF

temperature at the surface; was 61°'8 Fahr., at 10 feet 61°-5, at 20 feet
61°-2, and at 30 feet 60°'0.

Cults Loch (see Plate XXXIX.). — A small, nearly round loch, lying
among fields about a mile north-east of Castle Kennedy station. There is
a boggy stretch to the north-east of the loch, but no outflow could be
found. The greater part of the loch is shallow, and there is a crannog a
little west of the centre. East of the erannog is a small basin, in
which there is a maximum depth of 28 feet. The length is a quarter of a
mile, from south-east to north-west, and the breadth one-sixth of a mile.
The mean depth is over 9 feet, the area 17 acres, and the volume 7
millions of cubic feet. The drainage area is one-eighth of a square mile.
The loch is supposed to drain into the Chleury burn, which joins the Pit-
lanton burn near its mouth. The surface, on August 20, 1903, was 65'4
feet above sea-level, rather higher than the elevation determined by the
Ordnance Survey on August 2, 1893, viz. 65-1 feet. The temperature at
the surface was 61°'3,at 10 feet 60°'6,at 20 feet 60°-0,and at 25 feet 58°'7.

Loch Eee (see Plate CXXI.). — A small and nearly square loch in
the basin of the Luce, lying at an elevation of 639*6 feet, among the hills
on the east side of Loch Ryan, from which it is about 3 miles distant.
The length, measured diagonally from north-west to south-east, is one-
third of a mile, and the greatest breadth a quarter of a mile. The basin is
simple, deeper towards the south side-and east end, the slope of the bottom
from north and west very gradual. The maximum depth is 44 feet, and
the mean depth ] 5 feet. The area of the surface is about 27 acres, and
the volume of water 18 millions of cubic feet. The drainage is entirely
local, from boggy moorland, the area drained extending to half a square
mile. A very small burn flows out eastward, and by the Penwherran burn
joins the main water of Luce, which enters the sea in Luce bay at
Glenluce. The temperature of the water on August 21, 1903, was
uniformly 57°'5 Fahr. from the surface to a depth of 40 feet.

Whitefield Loch (see Plate XXXIX.). — A small loch, with densely
wooded shores, about 3 miles south-east of the- village of Glenluce. It is
half a mile long, and a quarter of a mile in greatest breadth. It is a
simple basin, with flattish bottom, interrupted by a number of small islands.
The maximum depth, 14 feet, is in the centre. The mean depth is 8
feet, the area 47 acres, and the volume 16 millions of cubic feet. The
drainage area is fully half a square mile. No large stream enters the
loch. The outflow is by a small stream flowing out from the west end.
The surface on October 17, 1906, was 192-7 feet above sea-level, or a foot
higher than the elevation determined by the Ordnance Survey on April 12,
1893, viz. 19T7 feet. The temperature was 49°'0 Fahr. throughout.

Eldrig Loch (see Plate XXXIX.). — A small loch in Wigtownshire, 8
miles south-west of the town of Wigtown. It is surrounded by pasture and

THE FRESH- WATER LOCHS OF SCOTLAND. 105

tnoorlaud, rising little higher than the loch. There are many boulders
along the west shore, and no rock was seen except at two spots on the east
side. The south end is weedy, and there the Old Mill burn goes out
through a boggy flat. Of the two crannogs the southern is covered, and
the northern is just seen above the surface. The length is half a mile,
and the greatest breadth one-sixth of a mile. The bottom is nearly flat,
and the maximum depth of 10 feet is in the centre of the loch. The
mean depth is nearly 6 feet, the area 44 acres, and the volume 11 millions
of cubic feet. The drainage area is about 2 square miles. The surface
on October 16, 1906, was 239-1 feet above sea-level, much higher than the
elevation found by the Ordnance Survey on May 25, 1893, viz. 234-5 feet.
The temperature was 50°-0 Fahr. throughout.

White Locli of Myrton (see Plate XXXIX.).— A small loch, within the
woods of Monreith park, 1 mile east of the village of Port William in
Wigtownshire. The shore where seen is stony. The south end and west
side are fringed with dense beds of reeds. The length is a little over half
a mile, and the greatest breadth nearly a quarter of a mile. It is a
simple basin, and relatively deep. The maximum depth of 40 feet is near
the west shore and the north end. The mean depth is nearly 14 feet,
the area 51 acres, and the volume 30 millions of cubic feet. The
drainage area is three-quarters of a square mile. The Barsalloch burn
flows out from the south end, and is controlled by a sluice. On the date
of the survey, October 15, 1906, the surface was 98-7 feet above sea-level,
or a foot higher than the elevation determined by the Ordnance Survey
on May 28, 1894, viz. 97'6 feet. The temperature at the surface was
53 -n Fahr., and at 36 feet it was 52 •?, or only <r-3 lower.

106 BATHYMETRICAL SURVEY OF

LOCHS OF THE BLADENOCH BASIN.

WITHIN the area drained by the river Bladenoch five lochs were sounded
by the Lake Survey, viz. Lochs Maberry, Fyntalloch, Ochiltree, Castle,
and Mochrum. The three first-mentioned lochs lie towards the head-
waters of the basin on the borders of Ayrshire and Wigtownshire, the
boundary-line crossing Loch Maberry, while the two last-mentioned lochs
are situated near the eastern shore of Luce bay. The river Bladenoch
rises in Loch Maberry, and after a course of some 3 miles is joined by
the Beoch Burn, bearing the overflow from Lochs Fyntalloch and Ochil-
tree, while the Water of Malzie, bearing the outflow from Castle and
Mochrum Lochs, falls into the Bladenoch about 4 miles before entering
Wigtown bay, at the town of Wigtown. Except the Loch of Fyntalloch,
the lochs are of fair size, three of them exceeding a mile in length, but
they are mostly very shallow, only Loch Ochiltree exceeding 15 feet in
depth.

Loch Maberry (see Plate XL.). — Loch Maberry lies about 10 miles
north-west of Newton Stewart, and trends nearly north and south. It
is considerably over a mile in length, with a maximum breadth of nearly
half a mile, the mean breadth being a quarter of a mile. The southern
portion of the loch for a quarter of a mile is narrow, but the main body
is nearly uniform in width. The superficial area is about 175 acres, or
over a quarter of a square mile, of which 67 per cent, is covered by less
than 10 feet of water. The western and southern portions of the loch
are shallow, the deepest part running along the eastern shore, where
the maximum depth of 14 feet was recorded. The volume of water is
estimated at 56 million cubic feet, and the mean depth at over 7 feet,
while the drainage area extends to 1\ square miles. The loch was
surveyed on August 17, 1903, when the elevation was found to be
388*7 feet above the sea ; when visited by the officers of the Ordnance
Survey on July 20, 1893, the elevation was 387-2 feet above sea-level.
The temperature of the surface water was 60°'0 Fahr., and at a depth
of 10 feet 59°-0.

Loch of Fyntalloch (see Plate XL.).— The Loch of Fyntalloch stands
close to, and at the same level as, Loch Ochiltree, into which it drains
by a stream only some 50 yards long. The length from north-west to

THE FRESH-WATER LOCHS OF SCOTLAND. 107

south-east is over a third of a mile, the maximum breadth being nearly
a quarter of a mile, and the superficial area 26 acres, of which 67 per cent,
is covered by less than 10 feet of water. The deeper water occupies a
central position, the maximum depth of 15 feet being found towards the
north-eastern shore. The volume of water is estimated at 8 million cubic
feet, and the mean depth at 7J feet, the area drained being about three-
quarters of a square mile. The temperature at the surface and at a depth
of 12 feet was identical on August 17, 1903, viz. 57°*8 Fahr.

LocJt Ochiltree (see Plate XL.). — Loch Ochiltree lies a mile and a half
to the east of Loch Maberry, and is nearly a mile in length from north
to south, the maximum breadth across the centre being over half a mile,
and the mean breadth a quarter of a mile. The superficial area is about
156 acres, of which 74 per cent, is covered by less than 10 feet of water.
At the northern end is a small deep basin, where the maximum depth of
34 feet was recorded. The volume of water is estimated at 52 million
cubic feet, and the mean depth at nearly 8 feet. Besides Loch Fyntalloch,
the little Black Loch lying to the north drains into Loch Ochiltree, the
total drainage area exceeding 2 square miles. The loch was surveyed
on August 17, 1903, when the elevation was 341*1 feet above the sea,
as compared with 341*5 feet determined by the Ordnance Survey on
December 14, 1893.

Temperature Observations. — Serial temperatures in the deepest part of
the loch gave the following results: —

Surface 58°-5 Fahr.

10 feet 58°-0 „

20 „ ' 57°'4 „

30 „ 57°'4 „

The range of temperature from surface to bottom was only 1°*1, and
this occurred between the surface and a depth of 20 feet, the readings at
20 and 30 feet being identical.

Castle Loch (see Plate XLL). — The Castle Loch lies to the west of the
Mochrum Loch, the nearest point about half a mile distant. It is slightly
smaller than Mochrum Loch, and of less irregular form, roughly triangular,
with the apex to the south-west. The surrounding moor is very rough,
with much rock showing, except on the north, where smooth rounded hills
rise, covered with grass or bracken. It measures nearly 1^ miles in length,
from south-west to north-east, and half a mile in greatest breadth. The
bottom is nearly flat, and the maximum depth is 11 feet. The mean depth
is 6^ feet, the area about 228 acres, or one-third of a square mile, and the
volume 65 millions of cubic feet, a very little less than that of Mochrum
Loch. The loch is fed by a few small burns. The outflow is by a large
biirn flowing eastward through a marsliy stretch into Mochrum Loch. No
rock was seen in the stream, but there was rock exposed near the outflow.
There is rock at Castle island, and several other small islands. Besides

108 BATHYMETRICAL SURVEY OF

the many islands there are numerous large boulders projecting above the
surface of the loch. The surface on October 25, 1906, was 264'6 feet above
sea-level, and fully 16 feet higher than Mochrum Loch; the elevation
found by the Ordnance Survey on April 15, 1893, was 264*2 feet above
the sea. The temperature was 48°*0 Fahr. throughout.

Mochrum Loch (see Plate XLL). — The Mochrum Loch, the largest in
the basin, is situated nearly midway between the towns of Wigtown and
Glenluce. It is of very irregular form, with rocky shores and many
rocky islets, the largest of which are covered with trees. Westward to
Castle Loch stretches flat boggy moor, on the east is cultivated ground and
woods. The length is 1 J miles, and the greatest breadth nearly one-third
of a mile. The depth is very low (mean 7 feet, maximum 13 feet), the
bottom in the open parts of the loch nearly flat or gently undulating.
The area is about 230 acres, or one-third of a square mile, and the volume
of water 68 millions of cubic feet. The drainage area, including Castle
Loch, is about 4 square miles. The only considerable feeder is the burn
coming from Castle Loch. The Water of Malzie issues from the east side
of the loch, and flows some 5 or 6 miles in an easterly direction to join
the river Bladenoch. On the date of the survey, October 24, 1906, the
surface was 248*15 feet above sea-level; the elevation determined by the
Ordnance Survey on March 27, 1893, was 247*7 feet above the sea.

The temperature was 48° -4 Fahr. at the surface, and 48°'0 at 10 feet.

THE FRESH-WATER LOCHS OF SCOTLAND. 109

LOCHS OF THE CREE BASIN.

THE river Cree, one of the largest streams entering the Sol way Firth
on the Scottish side, drains an extensive mountainous region lying chiefly
in the county of Kirkcudbright (see Index Map, Fig. 12). There are a
good many lochs in the basin, but owing to lack of boats it was possible
to survey only three of them. Loch Trool, the largest loch in the basin,
lies in Glen Trool, between the mountains Merrick and Lamachan, Loch
Dornal lies between Ayrshire and Wigtownshire, and Loch Kirriereoch is
near the head of the Water of Minnoch, and close to the Ayrshire border
in Kirkcudbrightshire. Lochs Moan, Neldricken, and Valley are con-
siderable lochs, which could not be surveyed.

Loch Dornal (see Plate XLII.). — Loch Dornal lies about 8 miles
north-west from Newton-Stewart, among rough moorland. The shores are
of stones and peat, with rock exposed at several places. There are many
small islands and boulders throughout the loch, which is of very irregular
form, shallow and flat-bottomed, 1<> feet in maximum depth, and 5 feet in
mean depth. The length is two-thirds of a mile, and the breadth one-
third of a mile. The superficial area is about 110 acres, and the volume
of water 2(3 millions of cubic feet. The drainage area is 2£ square miles.
The only stream entering is the Corwar burn, and the outflow is by the
Carrick burn, eastward to the river Cree.

The surface on August 17, 1903, was 386*2 feet above sea-level, or a
foot higher than the elevation determined by the Ordnance Survey on
July 12, 1893, viz. 385 '2 feet. The temperature of the water was 59°-5
Fahr. throughout.

Loch Kirriereoch (see Plate XLII.). — A very small and nearly square
loch, lying on elevated moorland, nearly 700 feet above sea-level, and
12 miles north of Newton-Stewart. The shores are chiefly of gravel
with boulders, while a deep bed of peat forms the east side. It measures
a quarter of a mile long, by one-fifth of a mile broad, and is 15 feet in
maximum depth. The mean depth is 7 feet, the area about 16 acres, and
the volume of water 5 millions of cubic feet. The drainage area is small.
Though the loch is close to the Water of Minnoch, the outflow is into the
Kirriemore burn, which joins the Minnoch about a mile to the south.
The temperature on August 15, 1903, was 56C§8 Fahr. throughout.

110

BATHYMETRICAL SURVEY OF

Loch Trool (see Plate XLII.). — Loch Trool is a narrow loch, situated
among the highest mountains of Galloway, 8 miles north of the town of

tyerrock

S 0 L W A Y r I R T H

English Miles

0123*5 10 15

FIG. 12. — INDEX MAP OF THE CBEE, FLEET, AND DEE BASINS,

Newton-Stewart. The shores are steep, rugged, and wooded. The centre
line of the loch is curved, the shore line undulating, and there are two
constrictions which separate three distinct basins. The shores and outflow

THE FKESH-WATER LOCHS OF SCOTLAND. Ill

are rocky. The length, in a straight line joining the ends, is 1 J miles, the
maximum breadth, near the upper end, a quarter of a mile. The eastern
basin is largest and deepest, with stoep sides and nearly flat centre, and
the maximum depth of 55 feet. The middle basin is similar, but smaller,
and has a depth of 48 feet. Between these basins the depth is only 22
feet. The western basin is separated from the middle basin by a strait, in
which the depth is only 12 feet — the slope is less steep, and the maximum
depth is 36 feet. Another constriction, with a depth of 10 feet, separates
a small expansion at the west end of the loch, with a depth of 23 feet.
The area of the loch is about 144 acres, or nearly a quarter of a square
mile, the mean depth is over 18 feet, and the volume of water 116 millions
of cubic feet. The drainage area is extensive, measuring 14f square miles,
and comprises the whole southern slope of the Merrick, the northern slope
of the Lamachan, and a number of lochs to the north-east, which were not
surveyed.

The principal streams feeding the loch are the Pulnabrick and Puchan
burns on the north, and the Gairland and Glenhead burns, which unite
and enter the head of the loch. The Water of Trool flows out to the
south-west, and joins the Minnoch about 2 miles distant. There is a
sluice at the outflow. The surface on August 14, 1903, was 246'35
feet above sea-level, or rather higher than the elevation determined by
the Ordnance Survey on June 26, 1894, viz. 245'9 feet. The temperature
varied over 2 from surface to bottom, thus : —

Surface 58C>3 Fahr.

10 feet 58°-2

20 „ 57°-0

30 „ 56°-8

40 „ 56°-5

50 „ 56°-0

From the following table it will be seen that in the fifteen lochs under
consideration 594 soundings were taken, and that the aggregate area of
the water surface is over 2 square miles, so that the average number
of soundings per square mile of surface is 280. The aggregate volume of
water contained in the lochs is estimated at 527 millions of cubic feet.
The area drained by these lochs is nearly 35J square miles, or 16J
times the area of the lochs.

112

BATHYMETEICAL SURVEY OF

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THE FRESH-WATER LOCHS OF SCOTLAND. 113

LOCHS OF THE FLEET BASIN.

THE only loch to be dealt with here is Loch Fleet, which forms the
source of the Little Water of Fleet, one of the tributaries of the Water of
Fleet flowing into Fleet bay, a branch of Wigtown bay. Loch Whinyeon
has been utilised to supply a mill at Gatehouse of Fleet, and its waters
have been diverted from the Dee basin, to which it originally belonged,
into the Fleet basin ; any overflow is into Tarn0 Water, a tributary of the
river Dee, and it will be treated of in that basin.

Loch Fleet (see Plate XLVL). — Loch Fleet lies about a mile to the
east of Loch Grennoch, over 2 miles to the west of Loch Skerrow, both
belonging to the Dee basin, and 8 miles north of Gatehouse of. Fleet.
Hills rise steeply on all sides of the loch, except to the south-east, where
the burn flows out. The loch trends from north-west to south-east, and
is over one-third of a mile in length, with a maximum breadth across the
upper end of a quarter of a mile, while its waters cover an area of about
43 acres. The basin is simple, the contours approximating to the outline
of the loch, and the maximum depth of 56 feet is centrally placed. The
volume of water is estimated at 41 million cubic feet, and the mean depth
at 22 feet. The loch was surveyed on July 24, 1903, when the elevation
was 1112'9 feet above the sea; the Ordnance Survey officers found the
elevation to be 1113*4 feet on September 1, 1894. The following
temperatures were taken in the deepest part of the loch : —

Surface 60°-2 Fahr.

10 feet 59°-8 „

25 „ 55°-6 „

50 „ 53°-0 „

The range of temperature was 7°*2, the greatest fall, between 10 and
25 feet, being 4-2.

114 BATHYMETRICAL SURVEY OF

LOCHS OF THE DEE (KIRKCUDBRIGHT) BASIN.

THE river Dee and its tributaries drain an extensive area in Kirkcud-
brightshire, including many lochs of greater or less importance, of which
a dozen were sounded by the Lake Survey, viz. Lochs Dee, Grennoch,
Skerrow, Lochenbreck, Woodhall, Dungeon, Harrow, Lochinvar, Ken, the
expansions of the river Dee below Loch Ken, Carlingwark, and Whinyeon.
The five first-mentioned lochs drain into the Blackwater of Dee branch,
while Lochs Dungeon, Harrow, Lochinvar, and Ken drain by the Water
of Ken branch, Loch Carlingwark at Castle Douglas drains into the river
Dee proper, and Loch Whinyeon into the Tarff Water branch, which joins
the Dee near its outfall at the head of Kirkcudbright bay. Five of the
lochs exceed a mile iu length, Loch Ken, the largest, being 4J miles in
length. The lochs are not very deep, Loch Dungeon, the deepest, having
a depth of 94 feet, Loch Grennoch 68 feet, Loch Ken 62 feet, and
Woodhall Loch 49 feet.

Loch Dee (see Plate XLIV.). — Loch Dee lies about 2 miles east of
Loch Trool in the Cree basin, and about 10 miles west of New Galloway,
amid high hills. The loch trends from south-west to north-east, and is
over a mile in length, with a maximum breadth across the south-western
end of about three-quarters of a mile, the mean breadth being one-third of
a mile. The superficial area is about 253 acres, and the drainage area
5i square miles. The maximum depth of 36 feet was found near the
south-western end, the mean depth being estimated at over 14 feet, and
the volume of water at 157 million cubic feet. It is an irregular loch,
a large peninsula extending into it from the south-eastern shore, and
dividing it into two portions, the north-eastern portion being shallow,
not exceeding 8 feet in depth, while the south-western portion forms
a simple deep basin. More than one-half of the lake-floor is covered
by less than 10 feet of water. The shores are mostly rock, but with
mounds of sand and gravel and many boulders; the river at the outflow
has rock on the north side. The loch was surveyed on July 30, 1903,
when the elevation was 739'2 feet above the sea; the water rises about
4 feet, and falls about a foot, from that level. The Ordnance Survey
officers found the elevation to be 739-5 feet on October 25, 1893. The
following temperatures taken in the deepest part of the loch show a
practically uniform temperature from surface to bottom : —

THE FRESH-WATER LOCHS OF SCOTLAND. 115

Surface 59°-2 Fahr.

10 feet 59°-2 „

20 „ 59°-2 „

30 „ 59°-0 „

Locli Grennocli (see Plate XLIV.). — Loch Grennoch lies about 7 miles
south-west of New Galloway. The hills are steep and high on both sides,
especially to the west at the south end. Rock is exposed all round the
loch, with many boulders and scanty patches of vegetation. The loch
trends nearly north and south, and is 2 miles in length, with a maximum
breadth of over one-third of a mile, the mean breadth being nearly a quarter
of a mile. Its waters cover an area of about 290 acres, or nearly half
a square mile, and it drains an area of over 5J- square miles. The
maximum depth of 68 feet was found towards the southern end. The mean
depth is estimated at 21 feet, and the volume of water at 263 million cubic
feet. The elevation was 690'7 feet above the sea when the loch was
surveyed on July 24, 1903, almost identical with that observed by the
Ordnance Survey on September 7, 1894, viz. 690'6 feet. A drift-mark
was observed 3 feet above the water, which might fall a foot lower. The
loch forms a simple basin, the deeper water occupying the southern half ;
the slope is steep in places, especially off the western shore near the
southern end. About 70 per cent, of the lake-floor is covered by less than
25 feet of water. Several streams drain into the loch, the principal ones
being the Cuttieniore burn and the Cuttie Shallow burn, entering on the
western side. The Pullaugh burn, flowing out at the northern end, is
a broad quiet stream with a very gentle fall for a couple of miles.

Temperature Observations. — The following serial taken in the deepest
part of the loch showed a range from surface to bottom of only 4°-2 Fahr.,
the greatest fall being one of l°-3 between 10 and 20 feet : —

Surface 60°-2 Fahr.

10 feet 59°-8 „

20 „ 58°-5 „

30 „ 58°-0 „

40 „ 57°'3 „

50 „ 56°-8 „

65 „ 56°-0 „

Loch SJcerrow (see Plate XLIV.). — Loch Skerrow lies between Loch
Grennoch on the west and Woodhall Loch on the east, being about 2 miles
distant from both, and 7 miles north of Gatehouse. The shores are
rocky, with numerous scattered boulders, and the islands are mostly
of rock, while stones are plentiful, especially towards the south ; a few-
small patches of yellow sand occupy the bays. The surrounding hills are
low and bare, with much rock exposed, and strewn with boulders. The
loch is subtriangular in outline, with the apex pointing south, and is
nearly three-quarters of a mile in length, with a maximum breadth at the
north end of half a mile, the mean breadth exceeding a quarter of a mile,

116 BATHYMETRICAL SURVEY OF

The superficial area is about 125 acres, and the drainage area about 6|
square miles. The maximum depth of 33 feet is centrally situated, the mean
depth being estimated at 12 J feet, and the volume of water at 68 million
cubic feet. About 40 per cent, of the lake- floor is covered by less than
10 feet of water, while a still larger area (about 46 per cent.) is covered
by water between 10 and 20 feet in depth. The loch was surveyed on
July 17, 1903, the elevation being 413'85 feet above the sea; the water
was high at that time — about 3 feet above the normal. The Ordnance
Survey officers found the elevation to be 415' 6 feet above sea-level on
August 23, 1894. The temperature of the water was practically uniform
throughout, varying only from 59°'3%to 590>7 Fahr.

Loclienbreck Loch (see Plate XLIV.).— This is a small quadrangular
loch lying between Loch Skerrow and Woodhall Loch, distant a little over
2 miles from the former, and a little under 2 miles from the latter, into
which it drains. The length from north-west to south-east is nearly half
a mile, and the maximum breadth over a quarter of a mile. The super-
ficial area is about 39 acres, and the drainage area over half a square mile.
The deepest part lies towards the eastern shore, off which the maximum
depth of 15 feet was found. The mean depth is estimated at 1\ feet, and
the volume of water at 13 million cubic feet. When surveyed on July 21,
1903, the elevation was 651-1 feet above the sea; the water might rise
about 2 feet above, and fall about a foot below, that level. The Ordnance
Survey found the elevation to be 650' 7 feet on April 5, 1894.

Woodhall Loch (see Plate XLIV.). — This is an elongate loch about
2 miles west of the river Dee, and about 6 miles north-west of Castle
Douglas. On the eastern side of the loch are cultivated fields bounded by
low grassy hills with few trees. The shores are largely of gravel, with
boulders, and exposed rock in places, but are mostly hidden by weeds. The
loch trends nearly north and south, but with the axis slightly curved, the
shore-line being much indented, and is 1 j miles in length. The maximum
breadth is about one-third of a mile, and the mean breadth about one-seventh
of a mile, the superficial area being about 168 acres, or a quarter of a
square mile. The drainage area is nearly 9 square miles, including that
of Lochenbreck Loch. The maximum depth of 49 feet was found towards
the northern end. The mean depth is estimated at nearly 20 feet, and the
volume of water at 144 million cubic feet. The loch was surveyed on
July 28, 1903, the elevation being 172-65 feet above the sea; the water
was low at that time, and might rise 3 or 4 feet higher, a drift-mark being
observed 2 feet above the surface. The elevation was 174-3 feet above sea-
level on August 4, 1894, when visited by the officers of the Ordnance
Survey. The outflow is a broad stream flowing first northward, then east-
ward to join the river Dee. The basin is, on the whole, simple, the
contour Ijnes being continuous, but the longitudinal section shows one

THE FRESH-WATER LOCHS OF SCOTLAND. 117

or two minor undulations. The axis of maximum depth lies towards the
western shore, off which the slope is in places steep. The deepest part,
exceeding 40 feet in depth, is situated over a mile from the upper end,
and over half a mile from the outflow. About 28 per cent, of the lake-
floor is covered by less than 10 feet of water, a rather larger area (about
•'>4 per cent.) being covered by water between 10 and 20 feet in depth.

Temperature Observations. — The following serials were taken in the
deepest part of the loch : —

Surface 63°'4 Fahr.

10 feet 62°-8 „

20 „ 59°-4 „

30 „ 58°-2 „

45 „ 56°-0 „

The range from surface to bottom was 7°«4, the greatest fall being one
of 3'4 between 10 and 20 feet.

Loch Dungeon (see Plate XLIV.). — Loch Dungeon lies about 6 miles
south of Loch Doon, and a similar distance east of Dairy. Hills rise
steeply on the south, side, and rugged crags at the west end, culminating
in Millfire (2350 feet) and Meikle Millyea (2446 feet). The general
trend is from west to east, the loch curving round a large peninsula called
the Point of Ringreoch. It is nearly a mile in length, with a maximum
breadth of a quarter of a mile, the superficial area being about 88 acres.
The loch drains an area of 2| square miles, the principal feeder being the
Hawse burn, entering near the west end, while a few minor streams flow
from the steep slopes of the hills to the west and south-west. The loch is
divided into three deep basins, the deepest situated at the west end, where
the slope is steepest, the maximum depth of 94 feet having been recorded
less than 150 yards off the western shore; the basin second in importance
lies at the east end, and has a maximum depth of 45 feet, while near the
centre of the loch is the smallest basin, having a maximum depth of 34
feet. About 73 per cent, of the lake-floor is covered by less than 25 feet
of water. The mean depth is estimated at 22 J feet, and the volume of
water at 87 million cubic feet. The loch was surveyed on August 6, 1903,
when the elevation was 1002-3 feet above the sea; a storm-beach was
observed 4 feet above the water, which might fall about a foot lower. The
southern and western shores are mostly of rock, with alluvial cones laid
down by the burns. The main inflow, at the west end, cuts through a long
sharp ridge of gravel, which abuts on the steep crags on the south, and
joins a ridge of rock on the north. The outflow falls several feet in about
100 yards, and passes first between and over boulders, and then over
rock. The water in the loch had a peculiar leaden or greenish-grey
slate colour.

Temperature Observations. — Serial temperatures taken in the eastern-
most basin gave identical readings of 54C'8 Fahr. at the surface, at 10

118 BATHYM ETHICAL SURVEY OF

feet, and at 35 feet, while in the deepest part of the loch the following
readings were recorded : —

Surface 53°-2 Fahr.

10 feet 53°-2 „

25 „ 53°-2

50 53°-2

60
70
75
90

52°-2
45°-2

440.3

440.5

Here also the temperature was uniform from the surface to a depth of
50 feet, but 1°'6 lower than in the eastern basin, the " sprungschicht "
lying between 60 and 70 feet, where a fall of 7° was recorded, the total
range being 8°*6.

Loch Harrow (see Plate XLIV.). — This is a small loch lying about a
mile north of Loch Dungeon, and about 7 miles north-west of Dairy. The
highest hill in the neighbourhood, Corserine, rises steeply to a height of
2668 feet to the westward of the loch, which trends east and west, and is
nearly half a mile in length, with a maximum breadth of about one-fifth
of a mile, and a superficial area of about 38 acres. It drains an area of
1J square miles, the main inflow being the Folk burn entering on the
northern shore. The maximum depth of 29 feet was observed towards the
east end, the mean depth being estimated at 11^ feet, and the volume of
water at 19 million cubic feet. The loch was surveyed on August 3, 1903,
when the elevation was 811'8 feet above the sea, nearly identical with that
determined on September 10, 1894, by the Ordnance Survey, viz. 811*6
feet; the water might rise 2 feet above, and fall a foot below, that level.
The basin is simple, the deeper water being centrally placed, but towards
the northern shore. About 52 per cent, of the lake-floor is covered by less
than 10 feet of water. Temperatures taken at the surface, at 10 feet,
20 feet, and 25 feet gave identical readings of 580<5 Fahr.

Lochinvar (see Plate XLIV.). — This small loch is situated about 3 miles
north-east of Dairy. It is irregular in outline, trending nearly north and
south, and over half a mile in length, with a maximum breadth of one-third
of a mile. The superficial area is about 68 acres, and the drainage area
1£ square miles. Three soundings were taken at the maximum depth of
10 feet, two towards the eastern shore, and the third off the western shore
near the north end. The mean depth is estimated at 6J feet, and the
volume of water at 19 million cubic feet. The loch was surveyed on
July 20, 1903, when the elevation was found to be 736'6 feet above the
sea ; the Ordnance Survey found it to be 735'4 feet on July 7, 189-i. The
outflow is by dam and sluice, the water at the time of the survey being
exactly at the level of the overflow. A drift-mark was observed two feet
above the water. The loch is flat-bottomed in character, most of the

THE FRESH- WATER LOCHS OF SCOTLAND. 119

soundings taken giving a depth of 9 feet. The shores are mostly of rock,
with stony debris, sandy gravel covering the eastern shore at the narrow
part near the north end. The temperature of the surface water on the
date of the survey varied from 58" -5 to 60°- 5 Fahr., a reading at a depth
of 8 feet giving 58-0.

Loch Ken (see Plate XLV.). — Loch Ken is the largest in the basin,
trending from north-west to south-east, the northern end being over a mile
south of New Galloway, and the southern end about 7 miles north of Castle
Douglas, the confluence of the Black Water of Dee with the river Dee being
looked upon as the southern limit of Loch Ken. The length exceeds 4J miles,
the maximum breadth across the centre of the loch at the entrance of the
Dullarg burn being about half a mile, and the mean breadth over a quarter
of a mile. The waters of the loch cover an area of about 867 acres, or 1^
square miles, and the area draining into it is very large, extending far to
the north and west, and including the other lochs within the basin dealt
with in the preceding pages, as well as a few lochs which were not
surveyed. The total drainage area thus amounts to about 282 square
miles. The maximum depth of 62 feet was recorded about a mile from the
upper end. The- volume of water is estimated at 792 millions of cubic
feet, and the mean depth at 21 feet. The loch was surveyed on July
14, 1903, the elevation being 142-0 feet above the sea.

The floor of Loch Ken is irregular, there being six separated areas
where the depth exceeds 25 feet, and two areas where the depth exceeds
50 feet. The 20-feet contour would be continuous almost from end to end,
except for a slight break opposite the entrance of the Arvie burn, where
the deepest sounding was 19 feet. The deepest basin occupies the wide
portion at the head of the loch, where there is a 25-feet area over 1 J miles
in length, enclosing a 50-feet area over three-quarters of a mile in length,
the maximum depth of 62 feet having been observed towards the eastern
shore. The second 50-feet area, based on a sounding in 52 feet, lies less
than a mile from the foot of the loch, occupying a central position in a
25-feet area three-quarters of a mile in length. To the south of this area
the water deepens again to 31 feet, and near the entrance of the Black
Water of Dee another sounding in 33 feet was taken. Of the entire lake-
floor 7 1 per cent, is covered by less than 25 fee* of water.

Temperature Observations. — Serial temperatures taken in the deepest
basin showed a gradual decrease of temperature, the total range from
surface to bottom being 4°-7 Fahr., as follows : —

Surface 60°-2 Fahr.

25 feet 59°-5

30 „ 58°-5

35 „ 57°-5

40 „ -... 56°-5

55 „ 55°-5

Expansions of the River Dee (see Plate XLV.J. — The expansions of the

120 BATHYMETRICAL SURVEY OF

river Dee immediately to the south of Loch Ken were surveyed on
July 15, 1903 — the day after Loch Ken had been sounded — when it was
found that the water had risen to the extent of about 3 feet, the elevation
being 144*9 feet above the sea. This was due to the fact that steady rain
set in at 3 p.m. on July 14, and continued almost without intermission all
night and all next day. The portion surveyed extends for 4 miles
southward from the entrance of the Black Water of Dee, as far as Cross-
michael, and consists of a series of widenings and narrowings of the river,
the wider parts usually coinciding with an increase in the depth. The
largest expansion is nearly half a mile in width, while the mean breadth
of the entire part surveyed is only one-sixth of a mile. The portion
surveyed covers an area of about 431 acres, or two- thirds of a square mile,
the area draining into it including Loch Ken and all the other lochs
previously dealt with, and extending to nearly 300 square miles. The
maximum depth of 44 feet was observed in the most northerly expansion,
but depths of 42 feet were recorded about 1J miles lower down, and in the
most southerly expansion surveyed, called Kirkland Loop. There are
seven areas where the depth exceeds 20 feet, including no fewer than
eleven isolated areas where depths exceeding 25 feet were found. The
large central expansion has a maximum depth of 27 feet, and the little
off-shoot on the western shore called Long Loch varies from 9 to 18 feet
in depth. Of the entire area surveyed about 81 per cent, is covered by
less than 20 feet of water.

Temperature Observations. — The surface temperature during the time
spent on the survey varied from 58°'3 to 60°'6 Fahr. A series taken in
the northernmost deepest basin indicated a slight inversion of temperature,
probably as a result of the rainstorm, the surface reading being 58°'3, that
at 20 feet 58°'6, and that at 39 feet 58°-8.

Carlingwark Loch (see Plate XLIV.). — Carlingwark Loch lies close to
the town of Castle Douglas, and drains into the river Dee by a straight
stream called Carlingwark Lane, 1^ miles in length. The loch is sub-
rectangular in outline, and trends nearly north and south, being three-
quarters of p, mile in length , and over one-third of a mile in maximum
breadth. The superficial area is about 105 acres, and the drainage area
over half a square mile. *The maximum depth of 17 feet is centrally
placed, and of the entire lake-floor about 74 per cent, is covered by less
than 10 feet of water. The mean depth is estimated at 7 feet, and the
volume of water at 31 million cubic feet. The loch was surveyed on
July 17, 1903, when the elevation was 143*0 feet above the sea ; the
elevation as observed by the Ordnance Survey on April 23, 1894, was
142-3 feet.

Loch Whinyeon (see Plate XLIV.). — Loch Whinyeon is a little sub-
circular loch about 5 miles north-east of Gatehouse of Meet. When
surveyed on July 22, 1903, the elevation could not bo determined by

THE FRESH- WATER LOCHS OF SCOTLAND,

121

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122 BATHYMETRICAL SURVEY OF

levelling, but was between 700 and 725 feet above the sea ; the water was said
to be high, and might fall several feet. The loch supplies water to mills at
Gatehouse by a tunnel made about 85 years ago through the hill to the
west into High Creoch burn. Originally the outflow was to the east into
the Tarff by a rocky channel, the overflow being over rock showing glacial
striae, and if the water were a foot higher than on the date of the survey,
it would overflow on the east, and some of the water would reach the Tarff
by the Glengap burn. The diameter from east to west is over half a mile,
and from north to south rather less than half a mile, the superficial area
being about 105 acres. The maximum depth of 33 feet was found towards
the western shore. The volume of water is estimated at 56 million cubic
feet, and the mean depth at 12^ feet. The lo-feet contour is continuous,
and encloses an area equal to two-thirds of the entire lake-floor. There
are two 20-feet areas, one towards the eastern shore, based on two
soundings in 22 feet, separated by a shallowing with 15 feet on it from the
deepest part of the loch lying to the west. The bottom is stony, no mud
coming up in the sounding tube, and few weeds were noticed anywhere.

From the table on p. 121 it will be seen that in the thirteen lochs under
consideration 954 soundings were taken, and that the aggregate area of
the water surface is about 4 square miles, so that the average number of
soundings per square mile of surface is 238. The aggregate volume of
water contained in the lochs is estimated at 1951 millions of cubic feet.
The area drained by these lochs is nearly 299 square miles, or 73 times
the area of the lochs.

THE FRESH-WATER LOCHS OF SCOTLAND. 123

LOCHS OF THE URR BASIN.

THE area drained by the Urr water (see Index Map, Fig. 13) includes
four lochs which were sounded by the Lake Survey, viz. Lochs Urr,

.. !>'. — 1NDFX MAP OF THE URR AND KITH BASINS.

124 BATHYMETRICAL SUKVEY OF

Auchenreoch, Milton, and Arthur. Rising among the hills in the north of
Kirkcudbrightshire, the Urr water enters the Rough firth, an inlet from the
Sol way firth, 2 or 3 miles south of tho town of Dalbeattie. Near its
source is Loch Urr, and a few miles farther south, at the Haugh of Urr, it
is joined by a burn coining from Auchenreoch Loch, while Milton Loch and
Loch Arthur drain by the Kirkgunzeou lane into Urr water at Dalbeattie.

Loch Urr (see Plate XLIII.). — Loch Urr is a picturesque loch of rhom-
boid form lying in the moorland about 13 miles north of Castle Douglas ;
the surrounding hills are highest to the north-east (Bogrie hill, 1416 feet).
The shores are of peat and gravel with boulders, rock being seen only on
the White isle promontory. It is two-thirds of a mile in length from north-
west to south-oast, and the breadth a little less, the area being about
106 acres. The basiu is simple, deepest towards the east shore, where the
maximum depth of 42 feet was found close to Rough island. The contour-
lines show that the slope is gentle from the shore to 20 feet, then steeper
to the centre. The mean depth is estimated at 12 feet, and the volume of
water at 56 million cubic feet. The area drained is about 3 square miles,
the only important feeder, Lochurr lane, coming from the north-east, and
the outflow is south-westward by the Urr water. The loch was surveyed
on July 23, 1903, when the elevation was 624*0 feet above the sea — almost
indentical with that determined by the Ordnance Survey on June 13, 1894,
viz, 623*9 feet. The water was low at the time of the survey, and might
rise 2 or 3 feet.

Auchenreoch Loch [see Plate XLIII.). — Auchenreoch Loch is a long
narrow loch near the village of Kirkpatrick Durham, and 9 miles west of
the town of Dumfries. It trends from north-east to south-west, and is a
mile in length, with a maximum breadth of nearly one-third of a mile near
the southern end, whence it narrows gradually towards the northern end.
The superficial area is about 86 acres, and the drainage area nearly 2 square
miles. The maximum depth of 34 feet was recorded in two places — (1)
near the middle of the loch, and (2) towards the southern end. The
volume of water is estimated at 44 million cubic feet, and the mean depth
at nearly 1 2 ' feet. The loch was surveyed on May 3, 1 905, when the
elevation was found to be 345*0 feet above the sea — nearly identical with
that determined by the Ordnance Survey on August 20, 1892, viz. 344-9
feet. The longitudinal section of the loch is undulate, though the cross-
lines of soundings give regular transverse sections. About a quarter of
a mile from the northern end, where the loch is very narrow, a depth
of only 8 feet was found, with deeper water both to the north and south.
The central deep area is of very limited extent, the single sounding in
34 feet being surrounded by much shallower water, the deepest soundings
in the vicinity being in 16 feet of water. In the wide southern portion
of the loch there is a 20-feet area about 300 yards in length. Of the

THE FRESH- WATER LOCHS OF SCOTLAND. 125

entire lake-floor about 42 per cent, is covered by less than 10 feet of water,
and about 8 per cent, by more than 20 feet of water, so that one-half is
covered by water between 10 and 20 feet in depth. The temperature of
the water was practically uniform throughout, the surface reading being
480<0 Fahr., while a reading at 34 feet gave 47°'2.

Milton Loch (see Plate XLIII.). — Milton Loch lies less than a mile to
the east of Auchenreoch Loch, and about 8 miles from Dumfries. It is
irregular in outline and conformation, the general trend being from north to
south, but the southern portion curves round Milton point towards the east.
The loch exceeds a mile in length, with a maximum breadth of half a mile.
The superficial area is about 153 acres, or nearly a quarter of a square
mile, and the drainage area is nearly 2 square miles. The maximum depth
of 15 feet was recorded both in the northern and southern parts of the loch,
there being two 10-feet areas separated by shallower water at the central
narrows, the greatest depth between Green island and the opposite shore
being 9 feet. The volume of water is estimated at 45 million cubic feet,
and the mean depth at nearly 7 feet. Of the entire lake-floor about 78 per
cent, is covered by less than 10 feet of water. The loch was surveyed on
May 3, 1905, when the elevation was 410*0 feet above the sea, or rather
higher than that determined by the Ordnance Survey on December 5, 1893,
viz. 409-6 feet. The temperature of the water was uniform throughout,
identical readings of 47°'0 Fahr. being taken at the surface and at 15 feet.

Loch Arthur (see Plate XLIII.).— Loch Arthur (or Lotus Loch) is
situated about 4 miles to the east of Milton Loch, and drains into the Kirk-
gunzeon lane at Killywhan Bridge. It is surrounded by cultivated stony
fields, with a strip of wood nearly all round and a plantation on the north-
east ; the shores are stony, with granite boulders. The loch is two-thirds
of a mile in length from east to west, with a maximum breadth across the
middle of nearly one-third of a mile, the superficial area being about
74 acres. The basin is simple, the contour-lines coinciding with the out-
line of the loch, and fairly deep. The maximum depth of 50 feet was
observed towards the south-eastern angle, but there is a considerable area
approximately in the centre of the loch, equal to one-fourth of the total
area, in which the depth exceeds 40 feet. The mean depth is estimated at
nearly 26 feet, or over one-half of the maximum depth, and the volume of
water at 83 million cubic feet. The loch was surveyed on May 4, 1905,
when the elevation was 239*8 feet above the sea, as compared with 240'1
feet determined by the Ordnance Survey on January 23, 1894. The
temperature of the water was practically uniform throughout, a reading at
the surface giving 47C'2 Fahr., and at 45 feet 46°'9.

126 BATHYMETRICAL SURVEY OF

LOCHS OF THE NITH BASIN.

THE extensive basin of the river Nith, which in its upper part winds
for so many miles through mountainous country, with several important
tributary glens, is in this upper part almost entirely devoid of lochs. A
few insignificant patches of water near New Cumnock were not surveyed.
The five lochs surveyed are found on small tributaries in the lower part of
the system, and on the west side of the river, the most, northerly being
Lochs Howie and Skae, which drain by the Cluden Water into the river
Nith near Dumfries, while Lochrutton Loch, Lochaber Loch, and Loch
Kindar lie within a few miles of the town of Dumfries, and the tribu-
taries on which they are situated drain into the tidal portion of the river,
where it expands into the Solway firth.

Loch Howie (see Plate XLVT.). — Loch Howie is a small, narrow loch
on the north side of the Blackcraig hill, 18 miles west of Dumfries, and
5 miles north-east of New Galloway village. The Black Craig rises
steeply on the south to 1332 feet; on the north the hills are lower. The
shores are of stony debris, with rock exposed at one part on the south.
The loch trends from south-west to north-east, and is three-quarters of
a mile in length, the maximum breadth near the east end being one-eighth
of a mile, and the superficial area about 45 acres. There are two distinct
basins, the western one having a maximum depth of 39 feet, and the eastern
one 37 feet, separated by a shallow with only 7 feet on it. The mean depth
is 16 feet, and the volume 31 million cubic feet. The drainage area is
half a square mile. The outflow is by the Mid burn northward into the
Blackmark burn, thence into the Castlefern burn and Cairn water and
Cluden water. Loch Howie was surveyed on July 23, 1903, when the
elevation was 757-15 feet above the sea; on May 12, 1894, the Ordnance
Survey found the elevation to be 757*9 feet. The variation in the level
of i the water is small.

Loch SJcae (see Plate XL VI.). — A very small, subcircular loch to the
north of Blackcraig hill, and half a mile east of Loch Howie. On
the east the hill rises steeply to over 300 feet above the loch ; the west
side is low. The maximum diameter from north to south is a quarter of
a mile, the superficial area being about 20 acres. There is a small, deep
area towards the west shore, enclosing the maximum depth of 35 feet.

THE FRESH-WATER LOCHS OF SCOTLAND. 127

The mean depth is 9J feet, and the volume of water 8 million cubic feet.
The outflow is by a small burn flowing out over rock northward to the
Blackmark burn. The loch was surveyed on July 29, 1903, when the
elevation was 864'5 feet above the sea, as compared with 864*7 feet
observed by the Ordnance Survey on May 15, 1894. A drift-mark was
noticed a foot above the water.

LocJirutton Loch (see Plate XL VI.). — A fair-sized loch used for the
supply of water to the town of Dumfries, which lies about 5 miles to
the north-east, while Milton Loch in the Urr basin lies about 3 miles to
the west. It trends nearly north and south, and is three-quarters of a
mile in length, with a maximum breadth across the middle of half a mile,
the mean breadth being a quarter of a mile. The superficial area is about
129 acres, and the drainage area exceeds 3 square miles. The maximum
depth of 58 feet was observed off the central part of the western shore, in
close proximity to the islet called Button's cairn ; but the deep water is
of very limited extent, the loch as a whole being flat-bottomed in character,
varying in depth from 10 to 15 feet. In fact, two-thirds of the lake-floor
is covered by water between 10 and 20 feet in depth, while only 4 per
cent, is covered by more than 20 feet of water. The mean depth is
estimated at 13 feet, and the volume of water at 73 million cubic feet.
The loch was surveyed on May 1, 1905, when the elevation was 305'7 feet
above the sea, as compared with 305'2 feet determined by the Ordnance
Survey on November 6, 1893. The temperature of the water was 48°-0 Fahr.
throughout.

Lochaber Loch (see Plate XL VI.). — A small, picturesque loch less than
2 miles south-east of Lochrutton Loch. The stony shores are wooded, and
the surrounding hills steep, the outflow at the north-western angle being
artificial. The loch is sub-triangular in outline, and over half a mile in
length from north-west to south-east, the maximum breadth across the
centre a quarter of a mile. The superficial area is about 52 acres, and the
drainage area exceeds a square mile. The maximum depth of 55 feet was
observed towards the south-eastern end, the mean depth being estimated
at 2 < »J feet, and the volume of water at 47 million cubic feet. The loch
is simple in conformation, but the deeper water lies towards the southern
end, the northern portion being shallow and weedy. About 71 per cent,
of the lake-floor is covered by less than 25 feet of water. The loch was
surveyed on May 4, 1905, but the elevation could not be determined ; on
January 16, 1894, the Ordnance Survey found it to be 298 feet above the
sea. Temperatures in the deepest part gave 48°*2 Fahr. at the surface,
and 47 3-0 at 45 feet.

Lof-h Kindar (see Plate XL VI.). — This picturesque loch is situated
about a mile inland from the Sol way firth, at the mouth of the river Nith.
The shores and islands are stony, the latter probably moraine mounds.

128 BATHYMETRICAL SURVEY OF

The western shore is wooded where rises the steep slope of Criffel, covered
with numerous boulders, while the eastern shore is bordered by cultivated
fields. The portion to the east of the large island is mostly filled with
reeds, and there are narrow strips of reeds on many parts of the western
shore. The burn flows out among stones at the north end, and joins the
New Abbey Pow. The general trend is from south-south-east to north-
north-west, but the southern portion curves round a broad promontory
on the eastern shore to the north-eastward. Loch Kindar exceeds three-
quarters of a mile in length, the maximum breadth being one-third of a
mile, and the mean breadth a quarter of a mile. Its waters cover an area
of about 134 acres, and it drains an area of over a square mile. The
maximum depth of 41 feet was found towards the northern end. The
mean depth is estimated at 14| feet, and the volume of water at 83 million
cubic feet. The soundings show that the conformation of the bottom is
rather irregular, comparatively shallow water occupying the central and
southern parts of the loch, while the deeper water occupies the northern
part, and sends out two branches, the longer one skirting the western
shore, and the shorter one running towards the eastern shore. Of the
entire lake-floor, about 35 per cent, is covered by less than 10 feet of
water, while 47 per cent, is covered by water between 10 and 20 feet in
depth. The loch was surveyed on May 2, 1905, when the elevation was
8 8 '05 feet above the sea, as compared with 88*3 feet determined by the
Ordnance Survey on February 19, 1894. Little variation was indicated
in the temperature of the water by observations taken in the deepest part
of the loch, the surface-reading being 490<0 Fahr., while readings at 28
and 38 feet both gave 48°'5.

THE FKESH-WATER LOCHS OF SCOTLAND. . 129

LOCHS OF THE ANNAN BASIN.

THE large area drained by the river Annan (see Index Map, Fig. 14)
is remarkably devoid of lochs, apart from a group of half a dozen small
lochs clustered near the town of Lochmaben, four of which were sounded
by the Lake Survey. The only other loch is the little Loch Skeen,
situated far to the north, on the borders of Dumfries- and Selkirk-shires,
near the source of the Moffat water, a tributary of the Annan. Loch Skeen
lies at an elevation of nearly 1750 feet above the sea, while the Lochmaben
lochs are all less than 200 feet above sea-level. The deepest lo ch is Mill
Loch, with a maximum of 55 feet ; Loch Skeen coming next with a maximum
of 36 feet; then Kirk Loch, with a maximum of 25 feet ; while Castle Loch
and Hightae Mill Loch are less than 20 feet in depth. The trout-fishing
in Loch Skeen is sometimes very good, but variable, while the Lochmaben
lochs are remarkable for their variety, Castle Loch, for instance, being said
to contain ten different species, including pike, perch, roach, bream, chub,
loch-trout, and vendace — the last mentioned a rare fish, peculiar to Castle
Loch and Mill Loch, which takes no lure, but is caught with the net.

Loch Skeen (see Plate XL VII.). — Loch Skeen lies about 9 miles north-
east from Moffat, and only 5 miles from St. Mary's Loch in the Tweed
basin. When engaged on the survey of St. Mary's Loch, our surveyors
were informed that there was no boat on Loch Skeen ; but one of them
went up to study the geology, taking a boatman with him, when they
found a boat without oars. With oars improvised from a broken fence,
they made a zigzag the whole length of the loch, a strong wind preventing
them from running transverse lines of soundings. The loch is elongate
in outline, trending from north-west to south-east, and three-quarters of
a mile in length, the maximum breadth being one-fifth of a mile. The
superficial area is about 69 acres, and the drainage area less than a square
mile. The deeper water is centrally placed, the maximum depth of 36 feet
being recorded rather nearer the northern than the southern end. A
sounding in 24 feet was taken near the northern end ; and a sounding in
26 feet off the central part of the eastern shore shows a steep slope in
that position. The mean depth is estimated at 18 feet, or one-half of the
maximum depth, and the volume of water at 53 million cubic feet. The
loch was surveyed on May 7, 19o5, but the elevation above the sea could
not be determined.

130

BATHYMETRICAL SURVEY OP

Mill Loch (see Plate XLVII.) — Mill Loch lies immediately to the
north of Lochmaben, amid cultivated fields. A small burn enters at the
north-western angle, coming from the little Upper Loch (which was not

Bartholomew Ed in?

012345 10 15

FIG. 14.— INDEX MAP OF THE ANNAN BASIN.

surveyed), while the outflow is by a built channel under the road into
Brumel Loch (now drained), and thence into Castle Loch. Mill Loch is
somewhat rectangular in outline, trending from north-west to south-east,

THE FRESH- WATER LOCHS OF SCOTLAND. 131

and nearly half a mile in length, with a maximum breadth of one-fifth of
a mile. The superficial area is about 32 acres, and the drainage area
exceeds half a square mile. The maximum depth of 55 feet was taken
towards the southern end. The volume of water is estimated at 36 million
cubic feet, and the mean depth at 251 feet. The basin is simple, the
deeper water lying in the southern portion of the loch, the upper end
being comparatively shallow, with weeds in the northern angle. Off the
south-western shore the slope is steep, soundings in 26, 27, and 35 feet
having been taken close inshore ; and off the central part of the opposite
shore a sounding in 38 feet was taken a short distance out. The deepest
part of the loch is flat-bottomed in character, no less than three consecutive
soundings being taken at the maximum depth of 55 feet, and the area of
the lake-floor covered by more than 50 feet of water is equal to 16 per
cent, of the total area, while that covered by less than 25 feet of water is
equal to 58 per cent. The loch was surveyed on April 28, 1905, when
the elevation was 171 '8 feet above the sea. The temperature of the water
varied to the extent of less than 1° Fahr. from surface to bottom, the
reading at the surface being 46^5 ; at 25 feet 46°'2 ; and at 53 feet 45°'6.

Kirk Loch (see Plate XL VII.).— Kirk Loch lies to the south of Mill
Loch, and to the west of the northern portion of Castle Loch, into which
it drains by the Vendace burn. It is surrounded by stony fields, a circular
hill, called Castle hill, rising between it and Castle Loch. Kirk Loch trends
nearly north and south, and is less than half a mile in length, covering
an area of about 33 acres. Tbe maximum depth of 25 feet was taken
towards the northern end, the mean depth being 10 feet, and the volume
of Avater 15 million cubic feet. The basin is simple, with the deeper
water occupying the northern portion of the loch, soundings in 12 and
13 feet being taken quite close to the northern end. More than half the
lake-floor is covered by less than 10 feet of water. The loch was surveyed
on April 28, 19<>5, when the elevation was 157*15 feet above the sea.
The temperature of the water was practically uniform throughout, the
reading at the surface being 47°-4 Fahr., and at 23 feet 47°-2.

Castle Loch (see Plate XL VII.).— Castle Loch, the largest within the
basin, is situated immediately to the south of Lochmabeu. The shores
of the loch are gentle, grassy slopes, with patches of wood, and there is
a fringe of weeds nearly all round; the eastern shore where free from
reeds is stony. It receives the drainage from Mill and Kirk Lochs, and
the outflow is by a large burn (Valison burn) at the southern end through
a peaty flat. The loch is subtriangular in outline, the length from north-
west to south-east exceeding three-quarters of a mile, the maximum breadth
across the wide southern portion being two-thirds of a mile, while the
mean breadth is one-third of a mile. The superficial area is about 193 acres,
or nearly one-third of a square mile, the drainage area extending to nearly

132 BATHYMETRICAL SURVEY OF

4 square miles. Castle Loch is simple in conformation, and of a flat-
bottomed character, the deeper water, over 15 feet, occupying the central
and eastern parts of the loch, three soundings at the maximum depth of
18 feet being recorded to the north-east of the island. Of the entire lake-
floor, only 28 per cent, is covered by less than 5 feet of water, while
38 per cent, is covered by more than 10 feet of water. The mean depth
is estimated at 8^ feet, and the volume of water at 72 million cubic feet.
The loch was surveyed on April 27, 19U5, when the elevation was 135*7 feet
above the sea, as compared with 137'1 feet determined by the Ordnance
Survey on February 22, ] 899. The temperature of the water was uniform
throughout, readings at the surface giving 46J*9 Fahr., and at 18 feet 460-8.

Hiyhtae Mill Loch (see Plate XL VII.). — A small loch, pyriform in
outline, to the south of Castle Loch. Though the smallest of the group, it
drains the largest area, the overflow being carried by the Mill burn into
the Valison burn just before entering the river Annan. The loch trends
from north-west to south-east, tapering gradually towards the outflow at
the southern end, and nearly one-third of a mile in length, the superficial
area being about 19 acres, and the drainage area about 6J square miles —
an area over two hundred times greater than that of the loch. The basin
is simple, the deeper water lying in the broadest part of the loch towards
the upper end, the maximum depth of 13 feet having been found a short
distance from the north-eastern shore. The mean depth is 7^ feet, or more
than half the maximum, and the volume of water 6 million cubic feet. The
elevation was 137*2 feet above the sea on the date of the survey (April 29,
1905), when identical readings of 49°*0 Fahr. were taken at the surface
and at 12 feet.

From the following table it will be seen that in the fourteen lochs under
consideration, 599 soundings were taken, and that the aggregate area of
the water-surface is about If square miles, so that the average number
of soundings per square mile of surface is 335. The aggregate volume of
water contained in the lochs is estimated at 652 millions of cubic feet.
The area drained by these lochs is about 24J square miles, or 13 J
times the area of the lochs.

THE FRESH-WATER LOCHS OF SCOTLAND.

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134

BATHYMETRICAL SURVEY OF

LOCHS OF THE TWEED BASIN

THE large area drained by the river Tweed (see Index Map, Fig. 15)
is on the whole remarkably devoid of lochs. It is true there are a dozen
little lochs on the borders of Roxburghshire and Selkirkshire, drained by
the Teviot branch of the Tweed, but they are very small, and were not
sounded by the Lake Survey. The principal loch is the well-known
St. Mary's Loch, with the adjacent Loch of the Lowes, in Selkirkshire, on

English Miles

Bartholomew.

O S 10 ZQ 30

FIG. 15. — INDEX MAP OF THE TWEED BASIN.

the Yarrow branch of the Tweed, while a notable addition has recently
been made by the construction, for the supply of water to the city of
Edinburgh and surrounding district, of the Talla reservoir in Peebles-
shire, which lies about 6 miles west of St. Mary's Loch, on the Talla
branch of the Tweed. Of the three lochs surveyed, St. Mary's Loch is the
largest and the Loch of the Lowes the smallest, Talla reservoir being
intermediate in point of size : — St. Mary's Loch slightly exceeds 3 miles in
length, Talla reservoir is nearly 2J miles in length, while the Loch of the
Lowes is less than a mile in length ; the superficial area of St! Mary's

THE FRESH-WATER LOCHS OF SCOTLAND. 135

Loch is about 635 acres, of Talla reservoir about 299 acres, and of
the Loch of the Lowes about 99 acres, the aggregate area covered by
the three lochs being about If square miles; the maximum depth of
St. Mary's Loch is 153 feet, of Talla reservoir 73 feet, and of the Loch
of the Lowes 58 feet. These lochs are situated among the moorland
hills of the Southern Uplands of Scotland, the highest point being Broad
Law (2754 feet), the scenery of the district being pastoral in character.
The fishing in St. Mary's Loch and the Loch of the Lowes includes trout,
pike, and perch, while the fishing in Talla reservoir is governed by
regulations drawn up by the Water Trust.

Talla Reservoir (see Plate XLV1II.). — Talla reservoir is situated
about 10 miles north of Moftat, 14 miles south of Peebles, and about
2<> miles west of Selkirk, lying in a narrow valley, with high hills, smooth,
grassy, and round-topped, on both sides. The valley rises very steeply at
the head of the loch, and the inflowing river descends by a series of
cascades — the " Talla Linns " ; there was formerly a bog on the site of the
lower part of the loch. The Act of Parliament authorizing the construction
of this reservoir was passed in 1895, and ten years later the work was
completed. A huge embankment, 1300 feet in length, 600 feet in breadth
across the base and tapering to 20 feet in breadth across the top, was thrown
across the valley, the top of the embankment being 957 feet above sea-
level, and 7 feet above the sill of the waste weir, which is 200 feet in
length. On the date of the survey (July 24, 1906) the surface of the
water in the reservoir was 3J feet below the sill at the overflow, or
9 46 '5 feet above the sea.

Talla reservoir * trends from south-east to north-west, and is 2^ miles
in length, the maximum breadth. exceeding a quarter of a mile, while the
mean breadth is about one-fifth of a mile. The superficial area is about
299 acres, or nearly half a square mile, and the drainage area extends to
about 10 square miles. The principal feeders are the Gameshope burn
and the Talla water entering at the head of the reservoir, while the over-
flow is carried by the Talla water into the river Tweed at Tweedsmuir.
The maximum depth of 73 feet was observed quite near the embankment
at the northern end, whence the water shoals gradually towards the head.
The volume of water is estimated at 443 million cubic feet, and the mean
depth at 34| feet.

The following notes on the stocking of the Talla reservoir with life
are supplied by Mr. James Murray : —

" It was thought that the formation of the Talla reservoir would give a
good opportunity to study the incoming of life to a lake, and it was intended
to make as frequent visits as circumstances permitted, with that object.

* We are indebted to Mr. W. A. Tait, C.E., the engineer of the Edinburgh and
District Water Trust, for permission to trace the outline of the reservoir, reproduced
in the accompanying map (Plate XLVIII.).

136 BATHYMETRICAL SURVEY OF

The reservoir did doubtless afford the opportunity, but, as it turned out, it
would have been necessary to visit it at very short intervals. In January
there was an almost total absence of life ; in the following July the process
of stocking was almost completed — if all the kinds of life found in old lochs
had not arrived, those which had arrived were very well established and
distributed all through the water. In January, 1906, a few months after
the reservoir was filled, the temperature was 36° Fahr. at the surface.
No life whatever was found except a few individuals of a kind of crustacean,
a Cyclops not of the common £pecies found in lakes.

"It was not convenient to visit Talla again till July, 1906, when the
bathy metrical survey was made. The surface temperature was then 56°.
The three commonest lacustrine Crustacea were present — Daphnia hyalina
was scarce; Cyclops strenuus was abundant, but mostly immature, only
a few carrying eggs ; Bosmina obtusirostris was in extreme abundance.
The plankton rotifers found were Anurcea cochlearis, Polyarthra platyptera,
Synchseta pectinata, and Conochilus volvox. Noteus quadricornis, a rotifer we
have already found in Scottish lochs, and only in very shallow ones, was
fairly abundant at the surface over the deepest part.

" In March, 1907, the Crustacea were the same, but less abundant, and the
two rotifers Notholca longispina and Furcularia reinhardti were observed for
the first time. The temperature of the surface was 41°, and at 30 feet 39°-5.

" In contrast to the very rapid stocking of Talla is the case of the new
reservoir at Holl, in the Lomond Hills, in Fife, where we found none of the
common lake organisms after the reservoir had been open for a year or
two. In Logan reservoir, after three or four years of existence, the
phytoplankton was found very well developed, the diatoms imparting a
yellowish colour to the water, but the zooplankton was much less abundant.
These contrasted instances show how little we yet know about the factors
governing the stocking of a new lake."

Loch of the Lowes (see Plate XLIX.). — The Loch of the Lowes
lies at the head of St. Mary's Loch, into which it flows by a stream
about 150 yards in length, the fall between the two lochs being only about
a foot; at one time they probably formed a continuous sheet of water.
The loch is rectangular in outline, and trends almost north and south,
being nearly a mile in length, and less than a quarter of a mile in
maximum breadth. The superficial area is about 99 acres, and the
drainage area exceeds 10 square miles. The maximum depth of 58 feet
was observed towards the southern end of the loch. The volume of
water is estimated at 1 57 million cubic feet, and the mean depth at 36J
feet, or nearly two-thirds of the maximum. The basin is simple in con-
formation, and flat-bottomed in character, as is shown by the fact that,
while 25 per cent, of the lake-floor is covered by less than 25 feet of water,
34 per cent, is covered by more than 50 feet of water, although the
maximum depth is only 58 feet. The loch was surveyed on May 5, 1905,

THE FRESH-WATER LOCHS OF SCOTLAND. 137

when the elevation was 810'5 feet above the sea, nearly identical with the
elevation determined by the Ordnance Survey on May 18, 1896, viz. 810*4
feet.

Temperature Observations.— The following temperatures were taken in
the deepest part of the loch : —

Surface 46°-0 Fahr.

5 feet 44°-3 „

10 44°-0 „

25 „ 44°-0 „

56 „ 43°-0 „

The range from surface to bottom was 3°, a fall of 1°'7 being observed
between the surface and a depth of 5 feet, while the readings at 10 and 25
feet were identical.

St. Mary's Loch (see Plate XLIX.). — St. Mary's Loch is situated about
10 miles south of Peebles, 12 miles south-west of Selkirk, and 13 miles
north-east of Moffat, and is somewhat crescentic in outline, the narrower
upper portion trending nearly north and south, while the wider lower
portion trends in a north-easterly direction. It is 3 miles in length, the
maximum breadth exceeding half a mile, the mean breadth being one-third
of a mile. The superficial area is about 635 acres, or 1 square mile, while
the drainage area, including the area draining into the Loch of the Lowes,
extends to about 42 square miles. The maximum depth of 153 feet was
observed in the wider part of the loch, about 1^ miles from the northern
end. The volume of water is estimated at 2018 millions of cubic feet, and
the mean depth at 73 feet, or nearly half the maximum. There are two
deep basins exceeding loO feet in depth, separated at the entrance of the
Megget water by a ridge, on which a maximum depth of 88 feet was found :
the larger and deeper one towards the lower end is nearly 1J miles in
length, while the smaller one towards the southern end has a maximum
depth of 112 feet, and is over half a mile in length. The areas between
the contour-lines, and the percentages to the total area, are as follows : —

Feet. Acres. Per cent.

Oto 50 229 ... 35-9

50 „ 100 207 ... 32-6

100 „ 150 193 ... 30-4

Over 150 6 ... 1-1

635 100-0

The loch was surveyed on May o and 6, 1905, when the elevation was
found to be 809*5 feet above the sea, or more than a foot higher than the
elevation determined by the Ordnance Survey officers on May 18, 1896, viz.
808-2 feet.

Temperature Observations. — The following temperatures taken in the
deepest part of the loch at 6^30 p.m. on May 5, 1905, showed that the
range from surface to bottom was only 1°*8 Fahr. : —

138 BATHYMETEICAL SURVEY OF

Surface ... 420>8 Fahr.

50 feet ... 42°-0 „

100 „ ' ... 41°-7 ,,

140 „ 41°-0 „

Dr. L. W. Collet, who took part in the survey, supplies the following
notes on the formation of St. Mary's Loch and the Loch of the Lowes : —

" During the great Ice Age the Yarrow valley was occupied by a glacier,
as is shown by the U-shaped section and the moraine matter on the slopes
of the hills. In this valley we find the two picturesque lochs, St. Mary's
Loch and the Loch of the Lowes, which are both due to burn deltas dam-
ming the valley. Three dams are 'manifest : (1) one situated at the very
head of the Loch of the Lowes, formed by the junction of the deltas of two
lateral streams, the Chapelhope burn and the Eiskinhope burn ; a small
loch was very likely formed at one time behind this dam, as shown now by
an alluvial tract, which is the result of the filling up of the loch by detrital
matter brought down by the principal burn ; (2) one at the lower end of
St. Mary's Loch, due also to the junction of the deltas of two burns, the
Kirkstead burn and the Thorny cleuch ; this dam held back at one time
only one big loch ; (3) one formed by the deltas of the Ox cleuch and the
Thirlestane burn, which divided the big loch into two separate ones, now
represented by the Loch of the Lowes and St. Mary's Loch ; this dam has
led to the gradual filling up of the Loch of the Lowes by the detrital
matter brought down by the streams, as shown by the soundings, the
deepest recorded being 58 feet, while on the other hand the deepest sound-
ing recorded in the upper basin of St. Mary's Loch is 112 feet.

" St. Mary's Loch is fed by many streams : the first one on the western
shore is the Summerhope burn, the detrital matter brought down by which
causes a sinuosity in the 50-feet contour-line in that region; the Mare
cleuch has given rise to a small delta, which has little effect on the contour-
lines ; the most important tributary is the Megget water, which has laid
down a huge delta protruding across the lake, forming a sub-lacustrine
barrier, on which the maximum depth recorded is 88 feet; the Copper
cleuch has also formed a small delta, and has raised the floor of the bay
into which it flows.

" From a bathymetrical point of view, St. Mary's Loch is divided into
two basins separated by the sub-lacustrine ridge due to the deposition of
material brought into the lake by the Megget water. The deeper basin is
situated in the north-eastern part of the loch, and might be ascribed to the
combined effect of the two glaciers, the Yarrow glacier and the Megget
glacier, uniting at that place. It is difficult to decide whether St. Mary's
Loch is simply a barrier basin, or whether it partakes of the character both
of a barrier basin and a rock basin."

Mr. James Murray supplies the following notes on the biology of St.
Mary's Loch : —

" During the discussion as to the suitability of St. Mary's Loch as a

THE FRESH-WATER LOCHS OF SCOTLAND. 139

source of water-supply for the city of Edinburgh, objection was made to
the water on account of the presence of certain organisms in it, and
especially of the small crustacean (Daphnia) commonly called the Water-
flea. It was pointed out at the time by those conversant with such
matters that these Crustacea are usually present in all impounded waters,
and we shall see that the organisms found in the water of St. Mary's Loch
are those which are characteristic of all freshwater lakes in this country,
even of those which are reputed purest. Their presence does not, there-
fore, in itself constitute any objection to the water.

" The water of St. Mary's Loch was examined by the Lake Survey on
two occasions, early in May, 1905, and in the middle of January, 190(5.
In May the water was fairly clear, and there were only a few species of
animals and some microscopic plants found in it. There were four species
of Crustacea : Diaptomus gracilis, Sara, Cyclops strenuus, Fischer, Daphnia
hyalina, Leydig, and Bosmina obtusirostris, Sars ; one rotifer, Notholca
longispina, Kellicott ; and three diatoms, Asterionella formosa, Hass.,
Tabellaria flocculosa, Kiitz., and T. fenestrata, Kiitz., var. aster ionelloides,
Gmn. No other organism was at all abundant.

" All the species above enumerated are among the commonest of lacus-
trine organisms, and it would be difficult to find a loch in Scotland in
which all of them are not present.

" In January the condition of the water was very different. The quantity
of life was immensely greater, and rendered the water of a dull yellowish
colour, and so turbid that bright objects could only be seen at a depth of
about 3 feet. All the same species were present, but some of them were
more abundant than in May, and many species were present which were
not found in May. The Crustacea were the same, but the larvae of the
copepods were very abundant, and some of the Cyclops were carrying
eggs. Of rotifers four additional species were found : Anurcea cochlearis,
ConocJtilus sp., Polyarthra platyptera, and Triarthra longiseta. The con-
trast was greatest in the vegetable life. One greenish alga, forming little
clusters easily visible to the naked eye, was mainly responsible for the
turbidity of the water.

" This ' flowering of the lake ' in winter is not unfamiliar in Scotland,
and has been seen in Loch Earn, etc. It takes place when the temperature
is low (in St. Mary's 3S~ Fahr.). As the increase of life is not due
to high temperature, occurring, in fact, when the lochs are coolest, it may
be supposed tbat pollution of the water by sewage may have something to
do with it. At any rate, both St. Mary's Loch and Loch Earn receive a
good deal of sewage. These facts concern the open water of the loch,
which alone is of much importance in relation to water-supply for towns.
The life of the margin of St. Mary's, and of the mud on the bottom, was
also studied.

" The life of the margin, chiefly found among the mosses and other
aquatic plants, is much more abundant than that of the open water. It

140 BATHYMETRICAL SURVEY OF

includes animals and plants of a great many different classes, but the flora
and fauna of tins region resemble those of any highland lochs which we
have studied, and there is little calling for remark. A new species of
rotifer, Philodina hamata, Murray, a parasite on Gammarus (the fresh-water
shrimp), was found here.

" The mud of the bottom proved to resemble that of Loch Ness, and other
highland lochs in the comparative paucity of life. A few worms, Crustacea,
and molluscs are the commonest inhabitants of this region. The depth
of St. Mary's being moderate, some species were found which are absent
from the deeper muds of Loch Ness. Water-mites (Hydrachnida) of
several species were found, and a single small stickleback."

THE FRESH-WATER LOCHS OF SCOTLAND.

141

LOCHS OF THE MONIKIE BASIN.

WITHIN the area drained by the Monikie burn (see Index Map, Fig. 16),
which flows into the North sea at Carnoustie, are two (or rather three)
reservoirs used for the supply of water to Dundee, that were sounded by
the Lake Survey, viz. Monikie reservoirs and Crombie Den reservoir,
situated 7 or 8 miles south-east of Forfar, and about 4 miles north-west of
Carnoustie, at an elevation of nearly 500 feet above the sea.

English Miles
~* s~

FIG. 16. — INDEX MAP OF THE MONIKIE AND LUNAN BASICS.

Monikie Reservoirs (see Plate L.). — The two reservoirs together re-
semble the capital letter B in outline, and when full they stand at the
same level, but on the date of the survey (October 13, 19<»4) there was a
difference in level of nearly 2 feet, the elevation of the south pond being
476-6 feet, and of the north pond 474-8 feet, above the sea. The clear-
water basin could not be sounded, as it was under repair; it has a flat

142 BATHYMETRICAL SURVEY OF

bottom, with drains running through it, and overflows when the depth of
water at the north end attains 10 feet, the south end being about 3 feet
deeper. The area draining into the reservoirs is about 4 square miles.

South Settling Reservoir. — The south pond is the larger of the two,
being nearly half a mile in length, by nearly one-third of a mile in
breadth, covering an area of about 73 acres, and containing about 43
million cubic feet of water. The deepest sounding in 26 feet was taken
near the middle but towards the west side, where there is a considerable
area, equal to about 21 per cent, of the total area, covered by more than 20
feet of water. The mean depth is estimated at 13^ feet. The temperature
of the water was nearly uniform throughout, the reading at the surface
being 47°-l Fahr,, at 10 feet 47°'0, and at 25 feet 46°'8.

North Settling Reservoir. — The north pond is nearly half a mile in
length, by a quarter of a mile in maximum breadth, covering an area of
about 47 acres, and containing about 26 million cubic feet of water. The
deepest water occupies the north-eastern part of the pond, the maximum
depth of 22 feet being recorded close to the north-east shore, while an
isolated sounding in 20 feet was taken close to the western shore, near the
channel leading to the south pond. The mean depth is estimated at 12J
feet. The surface temperature was 46°'8 Fahr.

Crombie Den Reservoir (see Plate L.) lies about 2 miles to the north-
west of Monikie reservoirs, and is most irregular in outline. The wide
central portion is occupied by a large island, around which the water of the
reservoir forms a narrow channel, sending out a narrow shallow arm to the
west, and a wider deep arm to the south-east. The length from north-west
to south-east is nearly a mile, while the maximum breadth is only about
one-ninth of a mile, the superficial area being about 41 acres, and the
drainage area about 2J square miles. The maximum depth of 53 feet was
observed off the sluice at the south-east extremity of the reservoir, whence
the water shoals gradually towards the inflow at the opposite extremity. The
mean depth is estimated at 18 feet, and the volume of water at 31 million
cubic feet. The elevation could not be determined from bench-mark, but is
apparently about 500 feet above the sea. The reading on the sluice on
October 14, 1904, was 18*9. The water was practically uniform in
temperature throughout, the reading at the surface being 47°'5 Fahr., at 5
feet 47°-2, and at 50 feet 46°-9.

THE FRESH-WATER LOCHS OF SCOTLAND. 143

LOCHS OF THE LUNAN BASIN,

THE area draining by the Lunan water (see Index Map, Fig. 16) into
Lunan bay, on the east coast of Scotland, between Arbroath and Montrose,
includes three small lochs sounded by the Lake Survey, viz. Lochs Fithie,
Rescobie, and Balgavies. They lie towards the head-waters of the Lunan,
In miles or more from the sea, and 2 to 5 miles east of the town of Forfar,
forming a series trending generally in an east and west direction. Res-
cobie Loch, the central one of the series, is the largest, though Balgavies
Loch, the easternmost, is the deepest, Loch Fithie, the westernmost, being
the smallest in every respect. The lochs contain trout, perch, pike, and
eels, but the fishing is preserved.

Loch Fithie (see Plate LI.) is situated less than 2 miles east of Forfar,
surrounded by woods. There was a fringe of bushes nearly all round
some distance out in the water, and a prickly water-weed was very
abundant all over the loch, floating at times, but dredged also from the
deepest part of the loch. The length is nearly half a mile, and the width
nearly uniform, only about 150 yards, the superficial area being about
21 acres, of which about 70 per cent, is covered by less than 10 feet of
water, while in the eastern part of the loch there is a basin exceeding 1 0
feet in depth, with a maximum depth of 16 feet in its central part. The
volume of water is estimated at 7 million cubic feet, and the mean depth
at 7 ^ feet. The loch was surveyed on June 30, 1903, when the elevation
was 215*5 feet above the sea. The water rises and falls considerably, a
drift-mark being observed about 5 feet above the water, which was high at
the time of the survey, and might fall to the extent of several feet. The
inflow is at the east end on the southern shore, but there is no known
outflow. The temperature of the water was nearly uniform throughout,
the readings at the surface and at 10 feet being 62°*2 Fahr., and at 15
feet 62-1.

Hescobie Loch (see Plate LI.) lies about 3 miles east of Forfar,
surrounded by cultivated fields, with a strip of wood on the north
shore at the east end. The loch is 1| miles in length, by one-third
of a mile in maximum breadth, the mean breadth being one-fifth of a mile.
The superficial area is about 158 acres, or a quarter of a square mile, of
which about 57 per cent, is covered by less than 10 feet of water. The

144 BATHYMETRICAL SURVEY OF

10-feet basin is continuous, and about a mile in length, approaching com-
paratively close to the east end. The maximum depth of 23 feet was
observed immediately to the east of the central constriction, the depth in
the narrows being 14 feet, and in the large western expansion the greatest
depth is 19 feet. The volume of water is estimated at 69 million cubic
feet, and the mean depth at 10 feet. The area draining into the loch is
about 5J square miles. The survey was made on June 29, 1903, when the
elevation was 194-6 feet above the sea ; the Ordnance Survey map gives
196-0 feet, but the date when levelled is not indicated. A drift-mark was
observed 3 feet above the water, which might fall perhaps a foot lower,
giving a range in level of about 4 feet. The water was very dirty and
green in colour, and nearly uniform in temperature, the readings at the
surface and at 10 feet being 61°-9 Fahr., at 15 feet 61°-8, and at 20 feet

Balgavies Loch (see Plate LI.) is situated less than half a mile to the
east of Kescobie Loch, and about 5 miles from Forfar. The length is half
a mile, and the width nearly uniform, 250 to 300 yards, the superficial
area being about 52 acres, of which about 60 per cent, is covered by less
than 10 feet of water. The deepest part lies near the east end, where the
maximum depth of 32 feet was recorded, but there is an isolated basin in
the south-western portion of the loch with a greatest depth of 18 feet.
The volume of water is estimated at 22 million cubic feet, and the mean
depth at 9J feet. Balgavies Loch drains directly an area of two-thirds of
a square mile, but since it receives the overflow from Kescobie Loch, the
total drainage area is about 6 square miles. The loch was surveyed on
June 29, 1903, when the elevation was 194*5 feet above the sea; the
Ordnance Survey map gives 195'1 feet, but the date when levelled is not
indicated. A drift-mark was observed 2 feet above the water, which
might fall a foot lower. Serial temperatures were taken in the deepest
part of the loch, with the following results : —

Surface .................. 62°-5 Fahr.

lOfeet .................. 62°-4 „

20 „ .................. 55°-8 „

30 „ .................. 52°-5 „

There was a range of 10° throughout the body of water, the upper 10
feet being practically uniform, while between 10 and 20 feet there was a
fall of 6°-6, and between 20 and 30 feet a further fall of 3°-3.

THE FRESH- WATER LOCHS OF SCOTLAND.

145

LOCHS OF THE DEE (ABERDEEN) BASIN.

THE drainage basin of the river Dee (Aberdeenshire) is an extensive
one, exceeding 800 square miles, and includes one important loch (Loch
Muick) and several small ones, of which half a dozen were sounded by the
Lake Survey, viz. Lochs Callater, Muick, Davan, Kinord, Aboyne, and
Skene (see Index Map, Fig. 17). Loch Builg might also be included
among the lochs of the Dee basin, since a certain proportion of its over-
flow drains through the moraine matter at its southern end into the river

English Miles

Bartholomew.

0 5 10 20 30

FIG. 17. — INDEX MAP OF THE DEE (ABERDEEN) BASIN.

Gairn, but as its normal outflow is at the northern end into the river Avon,
it will be dealt with among the lochs of the Spey basin. Lochs Muick,
Callater, and Builg were made the subject of a short paper by Drs. Johnston
and Collet.*

Lochs Callater and Muick are situated in the upper reaches of the
river, to the south-west of Bal later, on the flanks of Lochnagar, the highest
peak attaining an altitude of 3786 feet, while the other lochs are connected
with the lower reaches of the river, to the east of Ballater. The fishings

* " On the Formation of Certain Lakes in the Highlands," Proc. Roy. Soc. Edin.,
vol. 26, p. 107 (1906).

L

146 BATHYMETRICAL SURVEY OF

in the lochs are preserved ; in Loch Callater there are a few trout, and
salmon late in the season, with pike and eels, and Lock Muick contains
trout, while Lochs Davan and Kinord contain pike and perch.

The upper lochs are mountain valley-basins, Loch Muick partaking both
of the character of a rock-basin and of a barrier- basin, while Loch Callater
is a true barrier-basin. The other lochs occur in the cup-shaped and
irregular depressions of the so-called morainic country generally found at
the base of a mountain region.

Loch Callater (see Plate LIT.) lies about 5 miles south of Braemar. On
both sides of the loch the hills rise with fairly steep slopes, especially at
the south-east end of the loch. No outcrops could be detected on the
shores, which are stony and composed of moraine matter. The loch trends
in a north-west and south-east direction, and is nearly a mile in length,
with a maximum breadth of one-fifth of a mile, the superficial area being
about 73 acres, and the drainage area nearly 8 square miles. The largest
feeder is the Allt an Loch, entering at the southern end. The maximum
depth of 30 feet was observed near the middle of the loch, but towards the
south-western shore. The volume of water is estimated at 38 million cubic
feot, and the mean depth at 12 feet. The floor of the loch shows one or
two slight irregularities, but on the whole the basin is simple in conforma-
tion; nearly one-half of the lake-floor is covered by less than 10 feet of
water. At the head of the loch is a large alluvial tract, which evidently
at one time formed part of the loch, the outflowing burn having cut its way
through the morainic barrier, and ultimately the lake may be entirely
drained, and converted into an alluvial plain. The loch was surveyed on
July 11, 1905, but the elevation could not be determined from bench-
mark; from spot-levels it was estimated to be about 1625 feet above the
sea. Temperatures taken in the deepest part of the loch showed a range of
10°*2 Fahr. from surface to bottom, the readings being —

Surface 66°-2 Fahr.

20 feet 59°-0 „

29 „ 56°-0 „

Loch Muick (see Plate LIIL), the largest and most picturesque of the
lochs in the Dee basin, lies about 8 miles south-west of Ballater amid wild
and magnificent scenery. On both sides of the loch the mountain-slopes
rise precipitously from the water's edge. The shores are stony, with many
big boulders. The loch trends in a south-west and north-east direction,
the axis being slightly curved, and is 2\ miles in length, half a mile in
maximum breadth, the mean breadth exceeding one-third of a mile. The
superficial area is about 549 acres, or nearly a square mile, while the
drainage area exceeds 14 square miles. The loch is fed by numerous
small streams, the largest feeder being the Allt an Dubh-loch, coming
from the Dubh Loch lying towards the head of the valley at an elevation of
about 2100 feet. The Glas Allt enters on the northern shore near the

THE FRESH-WATER LOCHS OF SCOTLAND. 147

south-west end, and has laid down a large delta, which is covered by
vegetation, thus contrasting with the other lake-shores, which are but
scantily clothed with vegetation. The Black burn, entering near the
middle of the southern shore, has not formed a delta, as it runs down a
rocky steep slope. The maximum depth is 256 feet, while the mean
depth is estimated at over 116 feet, and the volume of water at 2771
millions of cubic feet. The ratio of maximum depth to length is 46, and
of mean depth to length 101 ; these figures show the relatively great
depth of the basin, for in Loch Morar, the deepest of all British lakes
(Hi 1 7 feet), the ratio of maximum depth to length is 61, and of mean
depth to length 217, while the Lake of Geneva is 230 times longer than
deep.

The basin is simple in conformation, the shores sloping on all sides to
the deepest part of the loch, which is centrally placed. At the south-west
end the oO-feet and 100-feet contours are sinuous, due to the deposition of
material brought down by the burns. The mud from the deepest part is
black and peaty. The approximate areas between the contour-lines drawn
in at equal intervals, and the percentages to the total 'area, are as
follows : — ;

Feet. Acres. Per cent.

Oto 50 170 ... 31-1 !

50 „ 100 96 ... 17'5'

100 „ 150 69 ... 12-5

150 „ 200 91 ... 16-5

200 „ 250 113 ... 20-7

Over 250 ... 10 ... 1-7

549 100-0

These figures indicate the flat-bottomed character of the basin, the zone
between 200 and 250 feet being larger than any of the three preceding
shallower zones.

The loch was surveyed on July 8, 1905, but the elevation could not be
determined from bench-mark ; from spot-levels it was estimated to be
about 1308 feet above the sea, and on the Ordnance Survey map the
elevation of 1309*8 feet is given, though the date when levelled is not
indicated. The surface of the water was 1-2 feet below the large stone at
the south-east corner of the pier at His Majesty's boathouse. The water
was then very low— about 2 feet below the ordinary level — and might rise
4 or 5 feet above ordinary level, the range being about 7 feet.

Temperature Observations. — At noon on the date of the survey the
temperature of the surface water was 58°'2, and at 7 p.m. serial tempera-
tures gave the following results : —

Surface 56°-l Fahr.

50 feet 47°-2 „

100 „ 44°-3 „

225 ,. 43°-0

148 BATHYMETRICAL SURVEY OF

The range of temperature throughout the body of water was thus 15°'2,
a fall of 8C<9 being recorded between the surface and a depth of 50 feet,
and a further fall of 2°'9 between 50 and 100 feet.

Loch Davan (see Plate LIV.) lies about 5 miles north-east of Ballater,
and in close proximity to Loch Kinord. These two lakes are situated in
true " morainic country," that is to say, in hollows of the covering of
detritus left on the surface of the country when the ice-sheets retreated.
Loch Davan is three-quarters of a mile in length from east to west, the
greatest breadth from north to south being nearly two-thirds of a mile,
and the mean breadth one-third of a mile. Its waters cover an area of
about 146 acres, or nearly a quarter of a square mile, and the drainage
area extends to 11 J square miles. The maximum depth recorded was
9 feet, three soundings having been taken at this depth towards the south-
eastern shore. The volume of water is estimated at 25 million cubic feet,
and the mean depth at 4 feet. The elevation could not be determined, but
on the date of the survey (July 10, 1905) the surface of the water was 1*7
feet below the platform of the boathouse. The loch is in process of being
choked up by the water-lilies, which have increased since the Ordnance
Survey map was prepared. The 5-feet contour-line approximately indicates
the extension of the lilies, about 67 per cent, of the lake-floor being covered
by less than 5 feet of water. The temperature of the surface water was
66°-4 Fahr.

Loch Kinord (see Plate LIV.). — Loch Kinord (or Ceander) lies
immediately to the south of Loch Davan, though the two lochs are drained
by independent streams. Loch Kinord is a true " lake of the plains/'
lying in a depression between low hills composed of moraine matter, which
has been thrown down very irregularly. The length of the loch from
north-west to south-east exceeds a mile, and the maximum breadth exceeds
two-thirds of a mile, the mean breadth being a quarter of a mile. The
superficial area is about 186 acres, or over a quarter of a square mile, the
catchment area being nearly 3 square miles. The maximum depth of 12
feet was recorded near the eastern shore. The volume of water is
estimated at 41 million cubic feet, and the mean depth at 5 feet. The loch
is irregular both in outline and conformation, and there are many islets
composed of boulders. About 56 per cent, of the lake-floor is covered by
less than 5 feet of water. The elevation above the sea could not be deter-
mined, but at the time of the survey (July 10, 1905) the surface of the
water was 1-5 feet below the platform of the boathouse. The temperature
of the surface water was 65°'9 Fahr.

Loch of Aboyne (see Plate LII.). — The Loch of Aboyne is an artificial
one, the embankment at the boathouse having been made to form the loch,
which encloses one large and one smaller island. The elevation above the
sea could not be determined, but is estimated from spot-levels at about 430

THK FRESH-WATER LOCHS OF SCOTLAND. 149

feet ; on the date of the survey (July 13, 1905) the water was a foot below
the platform of the boathouse. The superficial area is about 38 acres, and
the area draining into it exceeds a square mile. The maximum depth of
1 1 feet was recorded between the large island and the western shore. The
volume of water is estimated at 10 million cubic feet, and the mean depth
at 6 feet. The liasin is of a flat-bottomed character, about 62 per cent, of
the lake-floor being covered by more than 5 feet of water. The surface
temperature was 67 '9 Fahr.

Loch of Skene (see Plate LIT.). — The Loch of Skene is situated about
9 miles to the west of Aberdeen, and is a mile in length by two-thirds of
a mile in maximum breadth. The superficial area is about 294 acres, or
nearly half a square mile, while the drainage area extends to about 17 \
square miles. The volume of water is estimated at 60 million cubic feet.
The elevation could not be determined from bench-mark, but on the date
of the survey (July 17, 1905) the water was 1-5 feet below the platform of
the Dunecht boathouse ; the Ordnance Survey officers found the eleva-
tion to be 274-8 feet above the sea on October 17, 1899. The loch forms
a shallow flat-bottomed basin, the great majority of the soundings being
taken at the maximum depth of 6 feet, the mean depth being nearly 5 feet ;
in fact, about 73 per cent, of the lake-floor is covered by more than 5 feet
of water. The surface temperature was 640<2 Fahr.

150 BATH YM ETHICAL SURVEY OF

LOCHS OF THE SLAINS BASIN.

THE little Sand Loch, lying close to the sea near Kirktown of Slains,
was surveyed along with the other Aberdeenshire lochs.

Sand Loch (see Plate LV.) is a small shallow basin situated amid flat
and uninteresting surroundings close to the seashore between Aberdeen
and Peterhead. It is a quarter of a mile in length, covers an area of about
10 acres, and contains barely a million cubic feet of water. The deepest
water is in the extreme north-eastern portion of the loch, where soundings
in 4 feet were taken, shallowing thence to the southward. The surface
temperature on July 15, 1905, was 67°*1 Fahr.

From the following table it will be seen that in the sixteen lochs
under consideration 879 soundings were taken, and that the aggregate
area of the water-surface is nearly 4\ square miles, so that the average
number of soundings per square mile of surface is 207. The aggregate
volume of water contained in the lochs is estimated at 5762 millions of
cubic feet. The area drained by these lochs is over 121 square miles,
or about 28 \ times the area of the lochs.

THE FRESH-WATER LOCHS OP SCOTLAND.

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152

BATHYMETRICAL SURVEY OF

LOCHS OF THE SPEY BASIN.

THE catchment basin of the river Spey is one of the largest of the
Scottish river-systems, extending to about 1200 square miles (see Index
Map, Fig. 18). The river is about 100 miles in length, rising a com-
paratively short distance to the east of the head of Loch Lochy in the

Bartholomew Ec/m '

0 -5 1O ZO SO

PIG. 18. — INDEX MAP OF THE SPEY BASIN.

Great Glen, on the flanks of Corrieyairack (2922 feet) and Cam Leac
(2889 feet) on the north, and of Creag Meaghaidh (3700 feet) and Cam
Liath (3298 feet) on the south, and flowing in a north-easterly direction
into Spey bay in the Moray firth, and being fed by numerous tributaries.

THE FRESH- WATER LOCHS OF SCOTLAND. 153

Near the source of the river is the little Loch Spey, and another small
hill-loch lies a short distance to the south. Proceeding eastward from
Loch Spey for about 8 miles, the river, having been joined by many
mountain streams, receives the outflow from Loch Crunachan, lying in
Glen Shirra, about 2 miles north of the head of Loch Laggan in the
Lochy basin. About 2 miles farther down, the Markie burn flows in from
the north and the Mashie water from the south ; and another 2 miles
further down, the Allt Breakachy flows in from the south, bearing the
outflow from Loch Gaol na Doire ; while about 4 miles still further down,
the river Truim flows in from the south, carrying the outflow from Loch
na Cuaich. At Newtonmore the river Calder flows in from the north, and
near Kingussie the river Tromie comes in from the south, bearing the
outflow from a connected series of three lochs (Lochs an Duin, Bhradain,
and an t-Seilich). About 4 miles down from Kingussie, Loch Insh lies
in the direct course of the river ; and in the immediate vicinity the river
Feshie flows in from the south. About 3 miles farther down, the river,
now flowing in a northerly direction, receives the overflow from Loch
Alvie, lying immediately to the west, and from Loch Gamhna and Loch
an Eilein, lying immediately to the east. At Aviemore the river Druie
flows in from the east, bearing the outflow from Loch Morlich and Loch
Eunach ; and a short distance further down, Loch Phitiulais lies close to
the river on the east ; while Loch Garten lies to the east near Boat of
Garten. About 4 miles down from Boat of Garten the river Nethy comes
in from the south-east, and about 15 miles farther down, the river Avon,
probably the most important of all the tributaries of the Spey, flows in
from the south-east, carrying the outflow from Loch Avon and Loch Builg.
Thence the river pursues a sinuous course to the sea, the river Fiddich
coming in on the east, about 10 miles down from the entrance of the
river Avon.

Of the numerous small lochs within the basin, thirteen were sounded
by the Lake Survey, viz. Lochs Cruuachan, Gaol na Doire, na Cuaich,
an Duin, Bhradain, an t-Seilich, Insh, Alvie, Gamhna, an Eilein, Morlich,
Phitiulais, and Builg. The most important of the lochs which could not
be sounded are Lochs Eunach and Avon, lying at a high elevation in the
Cairngorm mountains. With one exception, the lochs surveyed exceed
half a mile in length, five of them exceeding a mile in length ; in maximum
depth they vary from 25 to K»2 feet, nine exceeding 50 feet in depth.
Loch Insh contains the largest volume of water, while Loch Morlich covers
the largest area, nearly half a square mile. Loch Builg lies on the border
between the Spey and the Dee basin, to which latter basin it contributes
to some extent, as mentioned when dealing with the lochs of the Dee basin.
Most of the lochs are situated in Inverness-shire, Loch an Duin lying
partly in Perthshire and partly in Inverness-shire, the county boundary
crossing the central part of the loch ; but Loch Builg lies in Banffshire,
just on the border of Aberdeeushiro. The fishings in the lochs are

154 BATHYMETRICAL SURVEY OF

preserved ; they contain trout, with pike in Lochs Alvie and Caol na l)oire,
salmon in Loch an t-Seilich, and char in Loch Builg.

Loch Crunachan (see Plate LVI.) lies about 7 miles to the north-west
of Dalwhinnie on the Highland railway, and 11 miles to the south-west
of Newtonmore, Loch Laggan hotel, at the head of Loch Laggan, being
less than 2 miles to the south, The loch trends in a north-east and south-
west direction, and is two-thirds of a mile in length, with a maximum
breadth of a quarter of a mile, covering an area of about 68 acres, and
draining an area of nearly 4 square miles. The maximum depth of 25 feet
was observed towards the south-west end of the loch. The volume of
water is estimated at 23 million cubic feet, and the mean depth at nearly
8 feet. The loch was surveyed on June 5, 1902, but the elevation could
not be determined; on December 18, 1872, the officers of the Ordnance
Survey found it to.be 878'9 feet above the sea. The loch forms a simple
shallow basin, a considerable area at the northern end being under a foot
in depth, and about 78 per cent, of the lake-floor is covered by less than
10 feet of water. Weeds are abundant, especially at the north-eastern
angle, where the burn flows out.

Temperature Observations. — Temperatures taken in the deepest part of
the loch gave the following results : —

Surface 56°-0 Fahr.

5 feet 54°-0 „

10 „ 48°-2 „

20 ,, 47°'5 „

These observations show a range of 8°-5 from surface to bottom, the
greatest fall being one of 5°-8 between 5 and 10 feet — a fall exceeding
1° per foot of depth.

Loch Caol na Doire (see Plate LVI.). — Loch Caol na Doire (or Coul-
tree) lies about 3 miles from Dalwhinnie, and about 5 miles to the east
of the head of Loch Laggan. In outline it is pear-shaped, trending nearly
east and west, and nearly three-quarters of a mile in length, with a
maximum breadth across the wide western portion of nearly one-third of
a mile. The superficial area is about 77 acres, and the drainage area
nearly lj square miles. The maximum depth of 55 feet was observed
approximately in the centre of the wide western portion of the loch.
The volume of water is estimated at 77 million cubic feet, and the mean
depth at 23 feet. The loch was surveyed on May 14, 1904, but the
elevation could not be determined ; on December 2, 1872, the Ordnance
Survey officers found it to be 1140'7 feet above the sea. The loch is
simple in conformation, and relatively deep, one-half of the lake-floor
being covered by more than 20 feet of water. The surface temperature
was 45°-0 Fahr.

THE FBESH- WATER LOCHS OF SCOTLAND. 155

Loch na Cuaich (see Plate LVII.) lies on the east side of Glen Truim,
about 5 miles north-east from the head of Loch Ericht. Stac Meall na
Cuaich rises to a height of 3000 feet immediately to the east of the loch.
Trending in a north-east and south-west direction, the loch is nearly a
mile in length, with a maximum breadth of a quarter of a mile near the
south-west end, whence it narrows gradually towards the opposite end.
The superficial area is about 116 acres, and the drainage area exceeds
2^ square miles. The maximum depth of 85 feet was observed approxi-
mately near the centre of the loch, but towards the south-west end. The
volume of water is estimated at 214 million cubic feet, and the mean depth
at 42 ^ feet. The loch was surveyed on May 12, 1904, and the elevation
from spot-levels was estimated to be about 1296 feet above the sea. The
loch forms a simple basin, the contour-lines coinciding approximately
with the outline, but approaching closer to the eastern than to the western
shore, indicating a steep slope on the eastern side ; in fact, in one place a
sounding in 50 feet was taken about 50 feet from the eastern shore, equal
to a gradient of 1 in 1. The surface temperature was 41°'8 Fahr.

Loch an Duin (see Plate LVII.) lies about 7 miles to the east of the
head of Loch Ericht, and 5 miles south-east from Loch na Cuaich, at an
elevation of 1600 feet among the mountains, which rise on the west to
2707 feet, and on the east to 2844 feet, above the sea, the lower slopes
forming steep screes of small material. The shores are all stony, and the
outflow to the north is among stones. Loch an Duin drains northward
into Loch Bhradain, and thence into Loch an t-Seilich. It is a long and
narrow loch, trending almost north and south, and over a mile in length,
the maximum breadth being less than one-fifth of a mile. The superficial
area is about 102 acres, and the drainage area exceeds a square mile. The
maximum depth of 102 feet was observed in the middle of the loch. The
volume of water is estimated at 134 million cubic feet, and the mean depth
at over 30 feet. The basin is simple, the deeper water occupying a central
position, where the contour-lines approach close to the shores, showing
that the sides are very steep ; in one place off" the eastern shore a sounding
in 45 feet was taken about 50 feet from shore. The 25-feet basin is rather
more, and the 50-feet basin rather less, than half a mile in length, the two
ends of the loch being comparatively shallow, about two-thirds of the lake-
floor being covered by less than 25 feet of water. The deep, central part
is flat-bottomed, with the U-shaped section characteristic of ice-eroded
basins. The loch was surveyed on October 14, 1904, but the elevation
could not be determined; from spot-levels it was estimated to be about
1 590 feet above the sea. A gravelly beach was seen at places 2 feet above
the water. Temperatures taken in the position of the deepest sounding
showed that the water was practically uniform in temperature throughout,
the reading at the surface being 44°'2 Fahr. ; while at 50 and 100 feet
identical readings of 447<0 were recorded.

156 BATHYMETWCAL SURVEY OF

Locli Bhradain (see Plate LVIII.). — Loch Bhradain (or Vrottcn) lies
midway between Loch an Duin and Loch an t-Seilich, receiving the
outflow from the former and draining into the latter. Trending in a
south-west and north-east direction, it exceeds half a mile in length, with
a maximum breadth of one-fifth of a mile, covering an area of about 53
acres, and draining an area of 7 square miles, including Loch an Duin.
The basin is simple, with a maximum depth of 41 feet, recorded near the
middle of the wide northern part of the loch. The volume of water is
estimated at 34 million cubic feet, and the mean depth at 15 feet. The
loch was surveyed on May 18, 1904, but the elevation could not be deter-
mined; from spot-levels it was estimated to be about 1452 feet above the
sea. The surface temperature was 43°*4 Fahr.

Loch an t-Seilich (see Plate LVIII.) lies, about four miles to the east
of Loch na Cuaich, flanked on the west by Bogha-cloiche (2945 feet) and
on the east.by Mullach Coire nan Dearcag (2846 feet). It is the longest
of the Spey lochs, but is inferior in superficial area to Loch Morlich and
Loch Insh. In outline the lech is sub-rectangular, trending nearly north
and south, and is ]i miles in length, with a maximum breadth of nearly
half a mile at the southern end, whence it narrows slightly towards the
north, the mean breadth being one-third of a mile. The superficial area is
about 249 acres, and the area draining into it is nearly 25 square miles,
including Lochs an Duin and Bhradain. The maximum depth of 98 feet
was observed in two places, separated by shallower water : (1) nearly half
a mile from the northern end towards the eastern shore, and (2) over a
quarter of a mile from the southern end in a central position. The
volume of water is estimated at 448 millions of cubic feet, and the mean
depth at over 41 feet. The floor of the loch is somewhat irregular, show-
ing slight undulations both longitudinally and transversely, and the
coutour-lines are sinuous in places ; the deep water approaches very close
to the southern end, a sounding in 75 feet being recorded less than a
hundred yards from the southern shore. The loch was surveyed on May
17, 1904, but the elevation could not be determined ; from spot-levels it
was estimated to be about 1390 feet above the sea. Temperatures taken
in the southern deep basin showed a range of only 1°'7 Fahr. from surface
to bottom, the readings being —

Surface 44°'0 Fahr.

10 feet 43°-5 •„

20 „ 430>1 „

40 „ 42°-7 „

60 „ 42°-6 „

80 „ 42°-3 „

Loch Insh (see Plate LIX.) is situated about 5 miles to the north-
east of Kingussie, surrounded by woods (see Fig. 33), and may almost be
regarded as a large expansion of the river Spey. Though containing the

THE FRESH- WATER LOCHS OP SCOTLAND. 157

largest volume of \vater of the Spey lochs, it is inferior in superficial area
to Loch Morlich. Of irregular outline, it exceeds a mile in length from
south-west to north-east, — from inflow to outflow, — and from east to west
the diameter is little less than a mile, the mean breadth being nearly half
a mile. The superficial area is about 280 acres, or less than half a square
mile, and the total drainage area exceeds 316 square miles, including the
other lochs lying above it. The maximum depth of 100 feet was observed
towards the south-eastern shore. The volume of water is estimated at 454
million cubic feet, and the mean depth at over 37 feet. When the loch
was surveyed on October 9, 1903, the elevation could not be determined,
but was estimated to be about 4 feet higher than shown on the Ordnance
Survey map, where the elevation is given as 721 '4 feet above the sea,
though the date when levelled is not indicated, the water being rather high,
and flooding the shore in some places. Weeds were abundant at the inlet
and outflow of the river. The floor of the loch is somewhat irregular, as
shown by the sinuosity of the contour-lines, apparently brought about by
the deposition of material by the inflowing river, the contour-lines being
pushed out into the centre of the loch. The deep water lies in the
eastern portion of the loch, sending out a tongue along the western shore
into the south-western portion of the loch. Nearly one-half of the lake-
floor is covered by less than 25 feet of water. The temperature of the
water was practically uniform from surface to bottom, the readings at the
surface and at 50 feet being identical, viz. 45°-3 Fahr., while a reading at
85 feet gave 45°-l.

Loch Alvie (see Plate LIX.) is situated about 2 miles south-west of
Aviemore, and about 8 miles north-east from Kingussie. It is irregular in
outline, consisting of a wide central portion, sending out an arm to the
west and another arm to the north-east. The loch is nearly a mile in
length, with a maximum breadth of almost half a mile, covering an area of
about 139 acres, and draining an area of 11 square miles. The deepest
part lies in the north-eastern portion of the loch, the maximum depth of
70 feet having been observed less than one-third of a mile from the north-
east end. An isolated deep basin was also found in the western part of
the loch, soundings in 50 and 52 feet being recorded less than one-third
of a mile from the west end, while the wide central portion is less than 50
feet in depth. One-half of the lake-floor is covered by less than 25 feet of
water. The volume of water is estimated at 163 million cubic feet, and
the mean depth at 27 feet. The loch was surveyed on October 9, 1903,
but the elevation could not be determined ; from spot-levels the elevation
is apparently about 685 feet above the sea. The surface temperature was
47°-0 Fahr.

Loch Gamhna (see Plate LX.), the smallest of the Spey lochs surveyed,
lies about 2 miles to the south-east of Loch Alvie, on the opposite bank of

158 BATHYMETKICAL SUKVEY OF

the River Spey, and immediately to the south of Loch an Eilein, into
which it drains. Irregular in outline, the loch trends in a south-west and
north-east direction, and is less than half a mile in length by one-fifth of a
mile in maximum breadth, covering an area of about 25 acres. The
maximum depth of 41 feet was recorded in a small basin at the south-west
end of the loch ; there is a second deep basin, having a maximum depth of
29 feet, lying in the wide part of the loch towards the north-east end,
these two basins being separated by a shoaling covered by only 4 feet of
water, where the outline of the loch is constricted. The volume is
estimated at 10 million cubic feet, and the mean depth at 9^ feet, nearly
three quarters of the lake-floor being covered by less than 10 feet of water.
The loch was surveyed on October 14, 1903, when the elevation was found
to be 889*3 feet above the sea, or 6 feet lower than that determined by
the Ordnance Survey officers in September, 1868, viz. 895'2 feet. This
lowering is due to the banks of the stream giving way, and consequent
outflow into Loch an Eilein. The surface temperature was 46°'l Fahr.

Loch an Eilein (see Plate LX.) lies about 3 miles south of Aviemore,
amid picturesque surroundings. At the time of the survey, a couple of
ospreys were nesting in the ruins of the castle on the island (see Fig. 34).
Somewhat crescentic in outline, the loch exceeds a mile in length, along
the axis of maximum depth from south-west to north-east, the maximum
breadth being nearly half a mile. The superficial area is about 1 30 acres,
and the drainage area, including Loch Gamhna, is about 2| square miles.
The maximum depth of 66 feet was recorded towards the south-west end,
and deep water occurs also near the north-east shore, where soundings in
51 and 47 feet were taken, the water shoaling in the central part of the
loch to a depth of 20 feet. The volume of water is estimated at 144 million
cubic feet, and the mean depth at 25J feet, 54 per cent, of the lake-floor
being covered by less than 25 feet of water.

The loch was surveyed on October 14, 1903, when the elevation was
found to be 839*6 feet above the sea, or nearly a foot lower than that
observed by the Ordnance Survey officers oa September 21, 1868, viz.
840*4 feet above sea-level. Temperatures taken in the deepest part of
the loch showed a range from surface to bottom of only J° Fahr. : —

Surface 49°-2 Fahr.

10 feet 49°-0

20 48°-8

30
40
50
60

48°.8
48°-8
48°-7
48°-6

LocJi Morlich (see Plate LXI.), the largest of the Spey lochs in super-
ficial area, lies in Glen More, surrounded by woods, about 4 miles east
of Aviemore. The loch is sub-rectangular in outline, the length from

THE FRESH- WATER LOCHS OF SCOTLAND. 159

east to west exceeding a mile, the maximum breadth being two-thirds of
a mile. The superficial area exceeds 300 acres, or nearly half a square
. mile, and the drainage area is large — exceeding 17 square miles. The
maximum depth of 49 feet was recorded comparatively close to the east
shore, whence the water shoals gradually towards the west, the western
portion of the loch being very shallow ; nearly GO per cent, of the entire
lake-floor is covered by less than 10 feet of water. The volume is estimated
at 192 million cubic feet, and the mean depth at nearly 15 feet. The loch
was surveyed on October 10, 1903, when the elevation was 1045*0 feet above
sea-level, as compared with 1045'8 feet determined by the officers of the
Ordnance Survey on August 16, 1866. The temperature of the surface
water was 49°-l Fahr.

Loch Phitittlais (see Plate LX.), a small but relatively deep loch, lies
less than 2 miles north-east of Aviemore, and about 3 miles north-west
from Loch Morlich. The loch is over half a mile in length from north
to south, and a quarter of a mile in maximum breadth, covering an area
of about 67 acres, and draining an area of about 2J square miles. The
maximum depth of 74 feet was observed approximately near the centre
of the loch, but towards the northern end, the basin being simple in con-
formation. About 69 per cent, of the lake-floor is covered by less than
25 feet of water. The volume is computed at 67 million cubic feet, and
the mean depth at over 23 feet. The loch was surveyed on October 12,
1903, when the elevation was found to be 674*3 feet above the sea; the
Ordnance Survey map gives the elevation as 673*9 feet, but the date when
levelled is not indicated. Temperatures taken in the deepest part of the
loch showed a range from surface to bottom of only J° Fahr. : —

Surface 50°-0 Fahr.

10 feet 49°-8 „

20 „ 49°-8 „

30 „ 49-°6 „

40 „ 49°-6 „

50 „ 49°-4 „

70 „ ... 49°-4 „

Loch Builg (see Plate LXI.) lies nearly 20 miles east of Aviemore,
and about 6 miles north-west from Balmoral castle, in a valley running
north and south between Glen Avon and the head of Glen Gairn. A
small proportion of the overflow finds its way into the river Gairn, and
thence into the river Dee, as already stated ; but the normal outflow is to
the north, by the Builg burn and the river Avon, into the river Spey.
The reader is referred to the paper by Drs. Johnston and Collet, already
cited, for some remarks on the formation of Loch Builg. The loch is less
than a mile in length, by a quarter of a mile in maximum breadth, the
superficial area being about 77 acres. The maximum depth of 86 feet was
observed approximately in the middle of the loch. The volume of water

160 BATHYMETRICAL SURVEY OF

is estimated at 93 million cubic feet, and the mean depth at nearly 28 feet.
The floor of the loch is somewhat irregular, there being three deep basins
separated by two ridges. The largest and deepest basin occupies the
central portion of the loch, while towards the northern end two soundings
in 50 feet were taken, the greatest depth recorded on the intervening ridge
being 34 feet ; near the southern end a depth of 36 feet was found, the
deepest sounding on the ridge separating it from the central deep basin
being 21 feet. About 58 per cent, of the lake-floor is covered by less
than 25 feet of water.

The loch was surveyed on July 12, 1905, when the elevation was found
to be 1585-0 feet above the sea ; the elevation given on the Ordnance Survey
map is 1585'3 feet, but the date when levelled is not indicated. Tempera-
tures taken in the deepest part of the lech showed a range from surface
to bottom of 12° Fahr., the readings being as follows : —

Surface 61°-5 Fahr.

25 feet 56°-5 „

50 „ 52°-4 „

85 „ 49°-5 „

From the opposite table it will be seen that in the thirteen lochs under
consideration, 663 soundings were taken, and that the aggregate area of
the water-surface is over 2J square miles, so that the average number
of soundings per square mile of surface is 252: The aggregate volume of
water contained in the lochs is estimated at 2053 millions of cubic feet.
The area drained by these lochs is 350J square miles, or about 133
times the area of the lochs,

THE FRESH- WATER LOCHS OF SCOTLAND.

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162

BATHYMETRICAL SUKVEY OP

LOCHS OF THE LOSSIE BASIN.

WITHIN this basin (see Index Map, Fig. 19) the only loch surveyed was
the little Loch Spynie, lying between Elgin and Lossiemouth, which drains
into the Moray firth at Lossiemouth, not by the river Lossie, but by the
Spynie canal.

English Miles

Barth olomew.

O 5 IO 15 20

FIG. 19. — INDEX MAP OF THE LOSSIE, FINDHORN, AND NAIRN BASINS.

Loch Spynie (see Plate LV.) is said to have been reclaimed from the sea
in 1860, but it now stands about 5 feet above the sea-level, and the water is

THE FRESH- WATEJR LOCHS OF SCOTLAND. 163

quite fresb. It trends in a south-west and north-east direction, and is two-
thirds of a mile in length, by a quarter of a mile in maximum breadth,
covering an area of about 60 acres. The loch is very shallow, 93 per cent,
of the lake-floor being covered by less than 5 feet of water, and the south-west
end is filled with weeds. The maximum depth of 6 feet was observed in two
places, the mean depth being estimated at 2| feet, and the volume of water
at 7 million cubic feet. The drainage area is about 3 square miles. On
May 25, 19<>4, the surface temperature was 580<0 Fahr.

164 BATHYMETRICAL SURVEY OF

LOCHS OF THE FINDHORN BASIN.

WITHIN the catchment area of the river Findhorn (see Index Map,
Fig. 19) six lochs were surveyed, viz. Loch Moy, Lochindorb, Loch Allan,
Lochan Tiitach, Loch Dallas, and Loch of Blairs, the two first-mentioned
being the most important. Loch Moy is situated in Inverness-shire, while
Lochindorb and Lochan Tiitach lie on the borders of Elginshire and
Nairnshire, the other three being situated in Elginshire. The lochs contain
trout, but the fishings are preserved.

Loch Moy (see Plate LXII.) lies about 9 miles south-east of Inver-
ness, surrounded by woods, the Highland Eailway running along the
western shore. Moy hall, the residence of The Mackintosh, stands on the
northern shore, and on the larger island (Isle of Moy) is a granite monu-
ment, 70 feet high, erected to the memory of Sir zEneas Mackintosh in
1824, and the ruins of an old castle, while the smaller island (Eilean nan
Clach) was formerly used as a temporary prison. The loch trends in a
north-west and south-east direction, and exceeds a mile in length by nearly
half a mile in maximum breadth. Its waters cover an area of about 187
acres, or over a quarter of a square mile, and it drains an area exceeding
15 square miles. The maximum depth of 50 feet was recorded in the
south-eastern part of the loch, midway between the Isle of Moy and the
eastern shore. The volume of water is estimated at 157 million cubic
feet, and the mean depth at over 19 feet.

The soundings show some minor irregularities of the lake-floor, nearly
two-thirds of which is covered by less than 20 feet of water. The contour-
lines circle round the Isle of Moy, deep water being found both to the east
and west of that island ; off the western shore of the loch a sounding in
33 feet was recorded about 50 feet from shore, indicating a steep slope
in that position. The loch was surveyed on October 15, 1903, but the
elevation could not be determined from bench-mark ; judging from spot-
levels, it is about 880 feet above the sea. The temperature of the surface
water was 46°'0 Fahr.

Lochindorb (see Plate LXIIL). — Lochindorb (or Loch an-Dorb) lies
6 miles to the north-west of Grantown-on-Spey, and about 14 miles south
of Forres, draining by the Dorbock burn into the river Findhorn. Near
the eastern shore is a small island, with the ruins of Lochindorb Castle,

THE FRESH- WATER LOCHS OF SCOTLAND. 165

where human remains were found in 1866. The loch is sub-elliptical in
outline, trending in a south-west and north-east direction, and exceeds
2 miles in length. It is widest in the northern portion, where the maximum
breadth is two-thirds of a mile, narrowing towards the southern end, the
mean breadth exceeding one-third of a mile. Its waters cover an area of
about 540 acres, and it receives the drainage from about 12 square miles of
the surrounding country. The maximum depth of 51 feet was observed
over half a mile from the northern end and towards the western shore,
but the mean depth is only about 12 J feet, nearly one-half of the lake-floor
being covered by less than 10 feet of water. The deeper water (over 20
feet in depth) lies in the wide northern portion of the loch, to the north
and west of the island. The volume of water is estimated at 291 million
cubic feet.

The loch was surveyed on May 20, 1904, when the elevation was
found to be 968*6 feet above the sea; the level determined by the
Ordnance Survey officers on April 4, 1866, was 969'4 feet above sea-level.
The temperature of the surface water was 490>6 Fahr.

Loch Allan (see Plate LXII.) lies about 1J miles to the north of
Lochindorb, and is peculiar in outline, consisting of three distinct basins,
separated by two narrows. The southernmost basin is the largest and
deepest, having a maximum depth of 29 feet ; the central basin has a
maximum depth of 7 feet, with a comparatively large island near the
middle ; while the northernmost basin has a maximum depth of 10 feet,
with a small island near the middle. The length of the entire loch is
about half a mile, the southern and central basins trending nearly north
and south, while the northern basin trends nearly east and west, its waters
covering an area of about 22 acres, the volume of water being estimated at
In million cubic feet, and the mean depth at 10^ feet. The loch was sur-
veyed on May 23, 1904, the elevation being estimated at about 900 feet
above the sea. The surface temperature was 52°'0 Fahr.

Lochan Tiitacli (see Plate LXII.) lies about a mile north-west of Loch
Allan, and about 2 miles north of Lochindorb. It is subcircular in out-
line, and about a quarter of a mile in maximum diameter, with a superficial
area of about 19 acres. The volume of water is estimated at 4 million
cubic feet, and the mean depth at nearly 5 feet. The loch forms a simple
basin, the deeper water (exceeding 10 feet) occupying a central position, with
a maximum depth of 1 6 feet. The bottom is covered with peaty mud and
decomposing vegetable matter, from which a strong smell emanates. The
loch was surveyed along with Loch Allan on May 23, 1904, the surface
temperature being 51°'6 Fahr.

Loch Dallas (see Plate LXII.) lies about 8 miles south of Forres, at an
elevation of over 1000 feet above the sea. It is nearly half a mile in
length from north to south, by a quarter of a mile in maximum breadth,

166 BATHYMETRICAL SURVEY OF

covering an area of about 41 acres. It is very shallow, the maximum
depth being 8 feet, and the mean depth 3J feet, the volume of water being
estimated at 6 million cubic feet. The water was very brown and soft at
the time of survey (May 27, 1904), the surface temperature being 68°'0
Fahr.

Loch of Blairs (see Plate LXII.) is a small shallow loch lying 2 miles
to the south of Forres, a short distance to the east of the river Findhorn,
but draining by an independent stream (the Altyre burn) into Findhorn
bay. The length is one-third of a mile, and the superficial area about 28
acres. The maximum depth is 5 feet, and the mean depth 2J feet, the
volume of water being estimated at 3 million cubic feet. On May 26,
1904, the surface temperature was 64°'0 Fahr.

THE FRESH-WATER LOCHS OF SCOTLAND.

LOCHS OF THE NAIRN BASIN.

THE three lochs within the Nairn basin (see Index Map, Fig. 19) that
were sounded by the Lake Survey are situated in Inverness-shire at the
head of the river, over 20 miles to the south-west of the town of Nairn,
and comparatively close to the eastern shore of Loch Ness, being, indeed,
sandwiched between Lochs Ashie and Ruthven of the Ness basin. They
form a connected series, Loch Ceo-Glas flowing into Loch Dun na Seil-
cheig, the most important of the series, and thence into Loch a' Chlachain.
They all contain trout, and Loch Dim na Seilcheig also contains char, but
the fishing in it is preserved.

Loch Ceo-Glas (see Plate LXIV.) lies about 11 miles south of Inver-
ness, and only a mile and a half from the eastern shore of Loch Ness,
opposite Urquhart bay. Elongate in form, it trends in a south-west and
north-east direction, and is nearly a mile in length, though the maximum
breadth is only about one-seventh of a mile, the superficial area being
about 54 acres. The northern portion of the loch is shallow, with the
deeper water in the southern half, the maximum depth of 32 feet having
been recorded little more than a quarter of a mile from the southern end,
and towards the western shore, which is bordered by vertical and over-
hanging cliffs. The volume of water is estimated at 24 million cubic feet,
and the mean depth at a little over 10 feet. Nearly two-thirds of the lake-
floor is covered by less than 1 0 feet of water. The loch was surveyed on
May 1, 1903, when the elevation was found to be 762-9 feet above the sea,
or a foot lower than the level observed by the Ordnance Survey officers on
March 2*, 1S71. Temperatures taken in the deepest part of the loch
showed that the water was nearly uniform in temperature from surface to
bottom, the readings being : — f

Surface 46°'3 Fabr.

10 feet 46°-2 „

20 „ 46°'l „

30 „ ... 46°-0 „

Loch Dun na Seilcheig (see Plate LXIV.). — Loch Dim na Seilcheig
(or Duntelchaig) is a large and deep loch lying about half a mile to
the north-east of Loch Ceo-Glas, the difference in level being about
60 feet, Somewhat irregular in outline and variable in width, the loch
trends in a south-west and north-east direction, and is nearly 3J miles

168 BATHYMETRICAL SURVEY OF

in length, the maximum breadth towards the northern end exceeding
a mile, while the mean breadth exceeds half a mile. Its waters cover
an area of nearly 2 square miles, and the area draining into it, in-
cluding Loch Ceo-Glas, is about 8J square miles. The maximum depth
of 205 feet was observed about a mile from the southern end, but
an isolated sounding in 200 feet was recorded about half a mile farther
north, with shallower water between these two deep soundings. The
volume of water contained in the loch is estimated at 4599 millions
of cubic feet, and the mean depth at 84J feet. The soundings indicate
generally a gentle shore-slope, the steepest gradient being observed off the
south-eastern shore at the widest part near the foot of the loch, where a
sounding in 66 feet was recorded about 120 feet from shore. The floor of
the loch is somewhat irregular, the contour-lines being in places sinuous
in character, and the cross lines of soundings, especially in the northern
half of the loch, show several undulations. Thus the third line of sound-
ings from the northern end, proceeding from the south-eastern shore, shows
a deepening of the water to 65 feet, then a shoaling to 4G feet, then a
deepening to 70 feet, before finally rising towards the opposite shore.
The fourth line of soundings from the northern end, across the widest part
of the loch, proceeding also from south-east to north-west, shows that the
water deepens to 115 feet, then shoals slightly to 112 feet ; deepens again
to 127 feet, shoals again to 96 feet ; deepens slightly to 99 feet, shoals
again to 65 feet ; and then deepens to 76 feet before finally rising on
approaching the shore. The next line of soundings (the fifth from the
northern end) shows a shoaling near the middle covered by 105 feet, the
water deepening on both sides to 122 feet and 140 feet respectively. The
next line of soundings (the sixth from the northern end) shows a shoaling
towards the south-eastern shore covered by 60 feet, the water deepening to
86 feet between it and the shore. The next line of soundings (the seventh
from the northern end) reveals a shoaling towards the middle of the loch,
which is the more conspicuous because it is in close proximity to one of
the deepest soundings in the loch. Proceeding from the south-eastern
shore, the soundings deepen gradually to a depth of 154 feet, then a
slight shoaling to 143 feet was recorded, followed by soundings in 179 feet
and then 200 feet, when the bottom rises towards the north-western shore.
The following table, giving the approximate areas between the contour-
lines and the percentages to the total area, shows a larger area in the zone
between 100 and 150 feet than in the shallower zone between 50 and 100
feet, 40 per cent, of the lake-floor being covered by more than 100 feet of
water : —

Feet. Acres. Per cent.

Oto 50 441 ... 35-3

50 „ 100 310 ... 24-8

100 „ 150 317 ... 25-4

150 „ 200 180 ... 14-4

Over 200 1 ... 0-1

1249 100-0

THE FRESH- WATER LOCHS OF SCOTLAND. 169

The loch was surveyed on April 17 and 18, 1903, when the elevation
was found to be 702 '9 feet above the sea, or a little higher than that
observed by the Ordnance Survey officers on April 8, 1871, viz. 702'3 feet
above sea-level. Temperatures taken on April 18 showed that the water
was practically uniform in temperature throughout, the readings being : —

Surface 390>5 Fahr.

100 feet 39°-4 „

190 „ 39°-2 „

Loch «' Chlachain (see Plate LXIV.) lies immediately to the east of Loch
Dim na Seilcheig, the difference in level being about 20 feet. The western
shore consists of moraine mounds, which, where cut through by the road,
are seen to be composed of yellow gravel, with many immense boulders,
some perched; a very large boulder forms a projecting point near the
northern end of the loch. To the e*ast the whole hillside is strewn with
large boulders, with perched blocks on the higher hills.

The loch is irregular in outline, trending nearly north and south,
and is half a mile in length by one-third of a mile in maximum
breadth, covering an area of about 6< > acres. The drainage area exceeds
10 square miles, including Lochs Ceo-Glas and Dun na Seilcheig. The
loch forms a simple basin with an extensive shallow flat at the southern
end, due, apparently, to the deposition of material by the inflowing stream.
The deeper water lies towards the central part of the eastern shore, off
which two soundings at the maximum depth of 80 feet were recorded. The
volume of water is estimated at 78 million cubic feet, and the mean depth
at 30 feet, nearly one-half of the lake-floor being covered by less than 25
feet of water. The loch was surveyed on April 29, 1903, when the eleva-
tion was found to be 683*7 feet above the sea, or a little higher than that
observed by the Ordnance Survey officers on April 13, 1871, viz. 683'3
feet.

The temperature of the water from surface to bottom varied little, the
reading at the surface being 42' -7 Fahr. ; at 10, 25, and 50 feet, 42°-5 ; and
at 75 feet, 42°'0.

From the following table it will be seen that in the ten lochs under
consideration 655 soundings were taken, and that the aggregate area of the
water-surface is 3J square miles, so that the average number of soundings
per square mile of surface is 187. The aggregate volume of water con-
tained in the lochs is estimated at 5179 millions of cubic feet. The area
drained by these lochs is nearly 42J square miles, or about twelve times
the area of the lochs.

170

BATHYMETKICAL SURVEY OF

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THE FRESH- WATER LOCHS OF SCOTLAND. 171

THE LOCHS OF LISMORE.

THE Island of Lismore (see Index Map, Fig. 5), lying at the junction of the
Firth of Lome with the Sound of Mull and Loch Linnhe, some 5 miles north-
west of Oban, is a long narrow island less than 10 miles in length, trending
from south-west to north-east, and includes three small lochs which were
sounded by the Lake Survey, viz. Lochs Baile a' Ghobhainn, Kilcheran,
and Fiart. These lochs trend generally in the same direction as the
island, Loch Baile a' Ghobhainn lying towards the northern end, while
the other two are situated towards the southern end, Loch Fiart, the
southernmost, less than 2 miles from the southern extremity of the island.
The island is on the whole flat, the highest point, Barr Mor, between
Lochs Fiart and Kilcheran, being only 417 feet above sea-level. The
lochs, though small (one-half to two-thirds of a mile in length), are
relatively deep, all exceeding 50 feet in depth, the deepest, Baile a'
Ghobhainn, having a depth of 88 feet ; they contain trout, but the fishing is
preserved. The water of the lochs is impregnated with lime derived from
the limestone formation of the island, and the plants become thickly
encrusted with it ; sometimes MyriophyUum spicatum becomes so weighted
with lime that the plants are prevented from rising to the surface, and in
consequence do not bear fruit.

Loch Baile cC Ghobhainn (see Plate LXV.). — Loch Baile a' Ghobhainn
(or Balnagowan) is the largest of the three lochs in all respects, but
its drainage area is very small. The loch is widest and deepest in the
southern portion, narrowing and shallowing gradually towards the northern
end. The stones and reeds around the margin are thickly encrusted with
lime. The length is two-thirds of a mile, and the superficial area about
33 acres. The maximum depth is 88 feet, the mean depth nearly 39 feet,
and the volume of water 55 million cubic feet. The soundings show that
Loch Baile a' Ghobhainn forms a simple deep basin with steep shore-
slopes; gradients exceeding 1 in 1 were observed off the western shore
towards the southern end, where soundings in 61 feet and 22 feet were
recorded about 60 feet and 10 feet respectively from the shore, and off the
eastern shore, towards the northern end, where a sounding in 44 feet
was recorded about 30 feet from shore. The two ends of the loch are
comparatively shallow, and hence 41 per cent, of the lake-floor is covered
by less than 25 feet of water, but the deep basin partakes of a flat-bottomed
character, since over 17 per cent, of the lake-floor is covered by more than

172 BATHYMETRICAL SURVEY OF

75 feet of water, while only 15 per cent, is covered by water between 50
and 75 feet in depth.

Serial temperatures taken in the position of the deepest sounding on
August 12, 1904, showed a range from surface to bottom amounting to
15° Fahr., the fall between 25 and 50 feet being equal to about half a degree
per foot of depth, the readings being :—

Surface 620>5 Fahr.

10 feet 62°-4

25 „ 61°-5

35 „ ... 56°-5

50 „ 49°-3

88 „ 47°'5

Kilcheran Loch (see Plate LXV.) is half a mile in length, and covers
an area of 28 acres. At the northern end there is a narrow prolongation,
which could not be sounded because it was found impossible to get a boat
through the reeds at the narrows. The main body of the loch forms a
simple basin, the water deepening gradually on proceeding from the
southern end until the maximum depth of 60 feet is met with about
a quarter of a mile from the two ends. The mean depth is estimated at
21 feet, and the volume of water at 26 million cubic feet. Temperatures
taken on August 13, 1904, gave the following results : —

Surface 59°-4 Fahr.

10 feet 59°-8 „

30 „ 59°-5 „

60 „ 50°-5 „

There was heavy rain at the time, and for 10 hours previously, which
may account for the uniform temperature from the surface to 30 feet ;
between 30 and 60 feet a fall of 9° was recorded.

Loch Fiart (see Plate LXV.) is nearly two-thirds of a mile in length,
and covers an area of about 33 acres. The maximum depth of 58 feet was
recorded less than a quarter of a mile from the southern end. The longitu-
dinal line of soundings shows a slight irregularity of the lake-floor, for,
proceeding from the northern end, the water deepens gradually to 48 feet,
then shoals to 36 feet, whence the water deepens again to the point of
maximum depth. The volume of water is estimated at 34 million cubic
feet, and the mean depth at 23 feet.

THE FRESH-WATER LOCHS OF SCOTLAND.

173

THE LOCHS OF MULL.

THE island of Mull (see Index Map, Fig. 20) was the scene of some of
the preliminary work carried on by Sir John Murray and the late Mr. Fred. P.
Pullar. With the small machine designed by Dr. Ule, they sounded

OF
Ben More

3.85 a

MULL

English Mi/es

FIG. 20. — INDEX MAP OF THE ISLAND OF MULL.

Lochs Frisa, Ba, and Uisg, but, being led to doubt the trustworthiness of
that machine, they never published the results, and Mr. Pullar set to work
designing a new machine, which has since been used in sounding most of
the Scottish lochs. At the time of the visit of the Lake Survey staff only

174 BATHYMETRICAL SURVEY OF

the two largest lochs in the island (Lochs Frisa and Ba) could be sounded.
The first-named lies in the northern portion of the island near Tobermory,
while the other lies near the head of Loch na Keal, an arm of the sea
which nearly cuts the island into two portions, the connecting isthmus
between Loch na Keal and Salen bay being less than 3 miles across. The
scenery around the lochs is very fine, and the fishing, which is preserved,
includes salmon, grilse, Salmo ferox, sea- trout, and brown trout.

Loch Frisa (see Plate LXVII.) is the largest loch in the island, and
is distant about 3 miles from Tobermory. The margin is nearly all stony
and free from weeds, except at the south-east end, where the Ledmore
river flows out through an alluvial flat. The loch is elongate in outline,
and trends north-east and south-west, being 4J miles in length by over
half a mile in maximum breadth, the mean breadth exceeding one-third of
a mile. Its waters cover an area of If square miles, while the drainage
area is small, about 8 square miles. The maximum depth of 205 feet was
recorded near the middle of the loch, where the width is greatest. The
volume of water is estimated at 3603 million cubic feet, and the mean
depth at 76 J feet. The loch was surveyed on August 16 and 17, 1904,
but the elevation could not be determined ; the Ordnance Survey officers
found the elevation on November 22, 1866, to be 245*4 feet above the sea.

The soundings show that the floor of Loch Frisa is irregular. It is true
that the shallower contours are continuous, but they are in places sinuous
in character, while the 150-feet contour encloses no fewer than three
isolated areas. The largest and deepest of these 150-feet areas is centrally
placed, and is separated from the other two — one lying to the north-west,
the other lying1 to the south-east — by ridges covered respectively by 138
feet and 146 feet of water ; the northern area is based on soundings in
163 and 173 feet, while the southern area is based on a sounding in 165
feet. The deepest sounding (205 feet) is the only one recorded in over
200 feet of water. The longitudinal section A-B on the map shows
these three 150-feet basins separated by shallower water, and the cross-
section C-D, at the position of maximum depth, shows a conspicuous rise
of the bottom towards the western .shore. The next line of soundings
farther to the north also shows a conspicuous rise of the bottom in the middle
of the loch, where a sounding in 95 feet was taken between soundings in
128 and 170 feet. The soundings off-shore do not show any steep
gradients exceeding 1 in 1, the steepest shore-slope being observed in the
central part of the loch, opposite Lettermore, where, off the eastern shore,
a sounding was taken in 36 feet at a distance of 40 feet from shore, and off
the western shore soundings in 60 feet and 85 feet were taken at distances
of 80 and 100 feet respectively from shore.

The following table shows the approximate areas between the contour-
lines, and the percentages to the total area of the loch : —

THE FRESH- WATER LOCHS OF SCOTLAND. 175

Feet. Acres. Per cent.

Oto 50 ... 420 ... 38-8

50 „ 100 303 ... 27-9

100 „ 150 272 ... 25-1

150 „ 200 85 ... 7-9

Over 200 3 ... 0-3

1083 100-0

Temperature observations in the deepest part of Loch Frisa on
August 17, 1904, gave the following results : —

Surface 59°-l Fahr.

20 feet 59°-0

50 „ 58°-7

75 „ 58°-7

100 „ 56°-6

175 „ 55°-2

These readings show that the range of temperature from surface to
bottom amounted to only 4°, a fall of 2° being recorded between the depths
of 75 and 100 feet, while the upper layers of water were practically uniform
in temperature.

Loch Ba (see Plate LXVI.) is situated little more than 2 miles to the
south of Salen, and is surrounded by high hills except at the northern end
where the river Ba flows out. The water in the loch was very clear, not
peaty, and no phanerogamic flora was observed around the shores. The
loch trends in a north-west and south-east direction, and is 3 miles in
length, the maximum breadth near the northern end exceeding three
quarters of a mile. The superficial area is nearly l£ square miles, and the
drainage area is relatively large — nearly 20 square miles. The maximum
depth of 144 feet was observed in the wide northern portion of the loch, a
little more than a mile from the lower end. The volume of water is
estimated at 1602 million cubic feet, and the mean depth at 47J feet.
The loch was surveyed on August 15 and 16, 1904, but the elevation could
not be determined by levelling from bench-mark ; in March, 1867, the
Ordnance Survey officers found the elevation to be 40'6 feet above the sea.

The soundings show that the floor of Loch Ba is somewhat irregu-
lar, due principally to the fact that a shallow ridge crosses the loch
at its narrowest part, a little more than a mile from the southern end.
Here the breadth is only a quarter of a mile, and the deepest sounding
recorded on the ridge was 00 feet. The 25-feet and 50-feet areas are thus
continuous, and extend nearly the whole length of the loch, but the 75-feet
area is cut^ into two portions, the smaller portion to the south-east of the
ridge having a maximum depth of 95 feet, while the larger portion to the
north-west of the ridge includes the deepest water in the loch, the 100-feet
basin being nearly a mile in length. The longitudinal section A-B on the
map shows the shallow ridge referred to, while the cross-section C-D, taken
at the position of maximum depth, shows a regular bottom, but one or two

176 BATHYMETRICAL SURVEY OF

of the cross lines of soundings towards both ends of the loch indicate slight
undulations of the lake-floor.

The following table, showing the approximate areas between the
contour-lines, and the percentages to the total area of the loch, indicates a
larger area, and consequently on the average a gentler slope, between 25
and 50 feet than between the shore and the 25-feet contour : —

Feet. Acres. Per cent.

Oto 25 211 ... 27-2

25 „ 50 263 ... 33-9

50 „ 75 156 ... 20-1

75 „ 100 93 ... 12-0

Over 100 52 ... 6-8

775 100-0

Temperature observations in the deepest part of the loch on August 16,
1904, showed a nearly uniform temperature from surface to bottom,
probably brought about by a heavy gale which had been blowing during
the three previous days accompanied by much rain ; the readings indicated
a range of only half a degree Fahr. : —

Surface 60°-0 Fahr.

20 feet 59°-7 „

50 „ S9--7 „

122 , 59°-5

THE FRESH- WATER LOCHS OF SCOTLAND.

177

THE LOCHS OF BENBECULA.

THE island of Benbecula (see Index Map, Fig. 21) is in its physical
features a continuation of the low moorland tract of the south-eastern por-
tion of North Uist, the whole surface forming in like manner a maze of

i (•

\ / Oittr <S

English Miles

Bartholomew

FIG. 21. — INDEX MAP OP THE ISLAND OP BENBECULA.

land and water. There is no part of the island of any extent without
lochs. Most of these lochs are insignificant in size, and, like the lochs of
North Uist, they are of irregular form, contain numerous islands, and many
of them are to an even greater extent dotted over with boulders. A

178 BATHYMETRICAL SURVEY OF

casual inspection satisfies us that they can be of no great depth. The
selection of the lochs to be surveyed was determined by the presence of
boats, which were found only on some half-dozen of the larger lochs.

Loch Heouravay (see Plate LXVIII.). — Loch Heouravay is a loch of
extremely irregular form, lying close to the sea- shore on the east side of
* the island, where Loch Uskavagh cuts so deeply into the interior of the
land. It drains into Heouravay bay, an inlet from Loch Uskavagh, by a
stream a few yards in length. We were told that there was formerly a
mill on this stream and that the surface of the loch was kept at a higher
level by a dam with a sluice. When that was the case Loch Heouravay
might be a single loch ; the removal of the dam has divided it into five
distinct little lochs, differing slightly in level, and connected by very short
streams which fall only a few inches. The surroundings are rough moor-
land, the shores of rock, overlain in places by gravel and boulders. There
is rock close by the outflow.

The length, in a straight line between the most distant points, is lj
miles, following the middle line of the loch If miles. The greatest
breadth is1 a quarter of a mile, the mean breadth one-twelfth of a mile. The
greatest depth in the largest western basin of the loch is 25 feet ; the
maximum for the whole loch is in the smaller second basin, south of the
first, where there is a depth of 41 feet close to the shore; the third basin,
south of the second, has a depth of 1(3 feet; and the fourth and fifth
basins are only 5 and 6 feet deep. The mean depth of the whole loch is
about 7 feet. The superficial area is about 80 acres, and the contents 26
millions of cubic feet. The drainage area is nearly 2 square miles, and
includes many small lochs.

The surface of the lowest basin was 8'3 feet above sea-level, the upper-
most basin 9-6, and the largest fall, between first and second basins, 9
inches. The temperatures in the deepest basin on June 29, 1904, were —

Surface 60°-0 Fahr.

15 feet 59°-0 „

25 „ 56°-6 „

40 „ 55°-6 „

Loch nan Auscot (see Plate LXVIII.). — Loch nan Auscot is a very small,
roughly triangular loch, situated between Loch Heouravay and Loch
Hermidale. Its long axis runs north and south ; it is broadest towards the
south and narrows northwards to a point near Loch Hermidale into which
it drains by a very short stream. The shores are entirely of rock. It is
a quarter of a mile long, one-tenth of a mile in greatest breadth, and one-
twentieth of a mile in mean breadth. Relatively it is the deepest loch
surveyed in Benbecula, the maximum depth being 39 feet, and the mean
depth 17 feet. The area of the surface is only about 8 acres, and it
receives only surface drainage. The surface level was 13'0 feet above the sea.
The basin is quite simple, with deep water (of over 35 feet) in a straight

THE FRESH- WATER LOCHS OF SCOTLAND. 179

line along the centre line to near both ends. The temperature on June 30,
l!">4, had a range of 3r-2, viz.—

Surface 59°-2 Fahr.

20 feet 58-2 „

35 „ 56"-0 „

Loch Htrmidale (see Plate LXVIII.). — Loch Hermidale is the middle
loch of the chain of three lochs which were surveyed in the Haka basin. It
is of irregular form, broadest in the middle and tapering to each end. Its
long axis, somewhat curved, runs nearly north and south. It is surrounded
by low moorland and has rocky shores. It receives the burns coming from
Loch Aiiscot and from many little lochs to east and west, and overflows
into Loch na Deighe fo Dheas. It is fully three-quarters of a mile long,
a quarter of a mile broad, and one-eleventh of a mile in mean breadth.
The broad central part of the loch forms a simple basin, with the
maximum depth of 41 feet; a lesser basin to the north is 16 feet deep in
the centre ; the long narrow part running south towards Loch Auscot is
irregular, with islands and boulders, and has various holes of from 15 to 18
feet deep. The mean depth is 12| feet. The superficial area is 54 acres,
and the volume 29 millions of cubic feet. The drainage area, which
includes Loch Auscot and many smaller lochs, is just about a square mile.
On June 30, 1904, the surface was 8*7 feet above the sea. The tempera-
ture was almost uniform throughout, viz. —

Surface 59°-2 Fahr.

20 feet 59°-0 „

35 „ 58°-8 .„

LocJi na Deirjhe fo Dheas (see Plate LXVIII.) is the northernmost
loch of the Haka basin surveyed, lying close to the base of Rueval, the
highest hill in Benbecula, on its east side. It is of comparatively simple
oblong form, its long axis running north and south. There is a consider-
able inflow from lochs both to north and south. The outflow is by a
stream half a mile long, issuing from the east side into the Oban Haka, a
branch of Loch Uskavagh. The surrounding country is low moorland,
except where Etieval rises to the west, the shores almost entirely rock, here
and there covered by mounds of gravelly debris with boulders. The out-
flowing stream is bounded by rocks on both sides The loch is fully half
a mile long by a quarter of a mile broad, with a mean breadth of one-
eighth of a mile. The basin is a simple one, with the maximum depth of 34
feet near the centre, and the bottom sloping gently to the centre. The
southern bay is nearly flat and about 8 feet deep. The long inlet running
north has a depth of 9 feet at its mouth and 18 feet within. The mean
depth is K»i feet. The area of the surface is 52 acres, and the volume of
water 24 millions of cubic feet. The drainage area is Ij square miles.
On June 30, 1904, the surface was 7'5 feet above the sea. The tempera-
ture varied only 0°*2 of a degree from the surface, which was 59°'7 Fahr.,
to a depth of 30 feet.

180 BATHYMETRICAL SURVEY OF

Loch Olavat (see Plate LXIX.). — Loch Olavat, one of two lochs of the
same name, is situated nearly in the middle of the island, lying part on
each side of the main road, but nearer the south ford than the north one ;
the other Loch Olavat lies close to the north ford and is tidal. It is
extremely irregular in form, but is longest from north-west to south-east,
in which line it measures about If miles. In area it is the largest loch
surveyed in the island, measuring fully 140 acres, but is inferior in
length to both Loch Heonravay and Loch Langavat. Its greatest breadth
is half a mile, and mean breadth one-seventh of a mile. It is the
shallowest of the lochs, being only 12 feet in greatest depth, and 4 feet in
mean depth. The volume, 26 millions of cubic feet, is equal to that of
Loch Heouravay and about half that of Loch Langavat. When surveyed
on July 1, 1904, the height of the surface above sea-level was 16*0 feet.
It is chiefly fed by surface drainage from the boggy moor around, and by
small burns from many adjoining lochs. The outflow is controlled by a
sluice in connection with a corn mill some quarter of a mile to the south.
The area drained is considerable (2| square miles). Bock shows almost
everywhere round the shores, but is in many places covered with great
numbers of angular stones. The bottom of the loch is pretty regular, with
no abrupt deepenings, probably indicating that the silt is spread out and
levelled by the waves around and between the boulders and islands.
The temperature at the surface and at 10 feet was 59°'2 Fahr.

Loch Langavat (see Plate LXVI1L). — Loch Langavat is a long,
straight, and extremely narrow loch, running nearly east and west, close to
the south shore of the island, and east of the road. It is the longest loch
in Benbecula, being 24 miles long, but only a quarter of a mile in maximum
breadth, and less than one-tenth of a mile in mean breadth. The shores
are rock, forming low cliffs in the central and eastern parts. Towards the
west the north shore for nearly a mile is of stones and peat. Several
narrow inlets go off from the south shore, and there are many islands, all
narrow and running east and west. The maximum depth, 34 feet, is equal
to that of Loch na Deighe fo Dheas, and less than that of the other lochs
except Loch Olavat, but the mean depth, 8 feet, slightly exceeds that of
Loch Heouravay. The superficial area, about 124 acres, is only inferior to
that of Loch Olavat, while in volume (44 millions of cubic feet) the loch
is by far the largest in Benbecula. The loch is fed only by small burns
from many little lochs and by local drainage, and has its outflow to the
east into Loch a' Laip, through Oban Uaine. The area drained is only 1
square mile. When surveyed on July 4, 1904, the surface was 15'95 feet
above sea-level. Narrow as it is throughout, Loch Langavat is divided
into two nearly equal parts by a canal-like strait, one-third of a mile long
and only 5 feet deep. West of this it is on the whole very shallow, with
one small depression of 20 feet in the broadest part. East from the strait
it is relatively deep throughout, the deepest part of the main loch (30 feet)

THE FRBSHrWATBB LOCHS OF SCOTLAND.

181

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182 BATHYMETBICAL SURVEY OF

being close to the east end. The maximum depth of 34 feet is in one of
the inlets, just south of Emilia Cam Direach. The temperature at the
surface and 25 feet alike read 58°'0 Fahr., a gale prevailing at the time
accounting for the homogeneity.

From the table on p. 181 it will be seen that in the eleven lochs under
consideration 728 soundings were taken, and that the aggregate area of
the water-surface is 3| square miles, so that the average number of
soundings per square mile of surface is 194. The aggregate volume
of water contained in the lochs is estimated at 5475 millions of cubic
feet. The area drained by these lochs is just over 35J square miles, or
9| times the area of the lochs.

THE FRESH- WATER LOCHS OF SCOTLAND.

183

THE LOCHS OF NORTH UIST.

THE extraordinary maze of land and water, which the map shows to constitute
the greater eastern portion of the island of North Uist (see Index Hap, Fig.
22), cannot be fully appreciated when one is among the lochs. Although
this part of the land is very little above sea-level, the highest loch surveyed

r ^%-KV^

^w^O

PIG. 22. — INDEX MAP OP THE ISLAND OF NOBTH UIST.

standing at an altitude of only 35 feet, the undulatious of the stretch of low
moorland suffice to conceal most of the lochs, and rarely more than one or
two are in sight at one time. An ascent of one of the considerable
precipitous hills which rise close to the eastern shore (South Lee, 920 feet ;

184 BATHYMETEICAL SURVEY OF

Eaval, 1138 feet) gives an impressive bird's-eye view of the curious
conformation of country. In the western part of the island is an extensive
elevated tract, with few lochs, culminating in Marrival, 757 feet in height.
The lower ground towards the shore is, even in the western part of the
island, studded with little lochs. A great many of the lochs are tidal or
brackish, and the shore-line is further broken up by long ramifying arms
of the sea, which penetrate to the very heart of the island. When a
panoramic view is taken from one of the higher hills, it is obvious, from the
complicated shore-line, numerous islands, and absence of broad stretches of
water anywhere, that no great depth is to be expected. The lochs are in
fact shallow, with irregular bottoms, and bear no evidence of being rock-
basins, except in a few instances close to the bases of Lee and Eaval. The
considerable depth of 150 feet (having regard to the conformation of the
land) was observed in Loch Obisary.

The conditions under which the survey had to be made were peculiar.
Though we had the permission of the proprietor, Sir A. J. Campbell-
Orde, Bart., to use the estate boats, we found that very few lochs had
boats on them. The hotel had boats on a few of the best fishing lochs.
The difficulty was overcome through the kindness of the hotel proprietor,
Mr. McFadyean, of Lochmaddy, who allowed us to move his boats from one
loch to another, and provided us with gillies to assist in the transfer.
Most of the lochs are so chained together that the boats had usually to be
taken over very narrow isthmuses, but in some instances they had to be
laboriously hauled over ridges 100 feet or more higher than the lochs,
and for distances of about half a mile. Owing to this mode of survey many
small lochs were sounded, which would not have been regarded as worth
the trouble, because they happened to lie on the chain through which the
boat had to be taken. For the same reason many salt or brackish lochs
were sounded, but in many of these cases we were unaware of their
character till too late. Every gradation as to saltness is found, from lochs
filled at every tide to those which only receive at long intervals an
exceptionally high tide, and which are fresh enough to be drinkable, and to
support the usual freshwater fauna.

In measuring the height of the various lochs above sea-level we had
very few bench-marks to help us. There were no bench-marks except on
a few of the lochs near the road. The great number and close proximity
of the lochs rendered levelling over great distances comparatively easy.
Nearly all the lochs north of Loch Eport could be measured from one or
other of the ramifications of Loch Scadavay. From one bench-mark on the
Garnish road all the lochs to the south of Loch Eport, some of them 7
miles from the bench-mark, had to bo measured.

The lochs of North Uist are on the whole of such a uniform character

that it is considered needless to describe each loch in detail. Loch

Scadavay, besides being by far the largest of the lochs, shows in peculiar

erfection those features which are possessed in some degree by the great

THE FRESH- WATER LOCHS OF SCOTLAND. 185

majority of the lochs. This loch will therefore be described with some
fulness, and those which essentially resemble it, differing mainly in size,
will be included in the summary table giving the principal dimensions. A
few of the other large lochs, and any of rather different structure or
coming nearer true rock-basins, as well as Loch Obisary, on account of its
size and depth, will be described with more detail.

Of the thirty-nine lochs which were surveyed thirty-two are fresh-
water, and the remaining seven are more or less salt. Some of those
regarded as fresh may receive very exceptional tides. Lochs Duin, Strumore,
Oban a' Chlachain, and Leodsay are purely tidal, receiving ordinary tides,
though their level is only moderately affected by the tides. Loch Strnmore
rises and falls about 2 feet, while the whole tide is about 18 feet. Loch
Oban nam Fiadh is of an intermediate character, the flora and fauna
towards the lower end being purely marine, while in the upper part the
fauna is fresh-water. Loch Caravat is so fresh that we only learned its
tidal character from the account of the natives.

There are no important streams in North Uist. In the western part of
the island are some a few miles in length, and large enough to be dignified
by names, but in the part surveyed, where most of the lochs are situated,
they are extremely short, generally only a few yards long. The stream
which drains Loch Scadavay and its connected chain of lochs, though of
fair size, is of inconsiderable length. This stream, with those connecting
all the larger tributary lochs, has a total length of only about a mile, and
the longest portion of it, from Loch Scadavay to Loch Garbh-Abhuinn Ard,
is less than half a mile long.

The thirty-nine lochs surveyed belong to nineteen distinct basins. Most
of these contain only one loch, which usually drains directly to the sea by
a short channel, often no longer than the width of the public road. There
are twelve of these lochs, which are the only lochs in the basins to which
they belong, or the only lochs surveyed. They are Lochs Veiragvat, an
Duin, nan Geireann, Hosta, Oban a' Chlachain, Leodsay, an Tomain, Obisary,
a' Chladaich, Tormasad, a' Bharpa, and Buaille. The only important lochs
among these are Lochs Obisary and nan Geireann.

There are only six of the basins in which more than one loch was
surveyed. These basins cannot be distinguished by the names of the
streams draining them, as these are usually nameless. They are here
distinguished by the name of the most important loch in the basin, or by
that of the lowest, into which the others drain.

The Scadaiay Basin. — This is by far the largest of the basins, and
includes ten lochs which were sounded, besides many smaller ones. The
combined surface areas of all the lochs have a total measurement of nearly
:3f square miles, Loch Scadavay itself contributing nearly half of this. The
combined drainage area extends to 14J square miles, and of this Loch
Scadavay alone, excluding its tributary lochs, drains more than half, or over

186 BATHYMETKICAL SURVEY OF

8 square miles. The lowest loch of the basin is Loch nan Geireann, which
is tidal and communicates with the sea by a mere drain under the road.
Going up stream we come next to Loch Skealtar, then Loch Garbh-
Abhuinn, then Loch Garbh-Abhuinn Ard, and finally to Loch Scadavay.
Above Loch Scadavay there are two separate chains of lochs — on the west
that of Loch nan Eun, which communicates separately with Lochs na
Moracha and Huna ; on the east Loch a' Bhuird, which communicates with
Loch an Tairbeirt Stuadhaich, and that with Loch Deoravat.

Loch Deoravat (see Plate LXX.). — Loch Deoravat is the uppermost of
the chain of lochs running east from Loch Scadavay. It is only an inch
or two higher than Loch an Tairbeirt Stuadhaich, into which it drains ;
level, 21-3 feet above the sea. It is of simple oblong form, two-thirds of
a mile long from east to west, and one-third of a mile in greatest breadth.
Its simple shape does not correspond with a simple basin. The centre of
the loch is filled with large islands, and the contour of the bottom is very
irregular. There are a number of holes of from 23 to 32 feet in depth.
The maximum, 32 feet, lies between two of the islands. The loch is
picturesque, the shores rocky, rising to cliffs at the west end. The islands
are of varied character, some heather-covered and dark, others bare, grassy,
and green. One was blue from the profusion of the wild hyacinth. On
June 2, 1904, the temperature varied from 59°'2 Fahr. at the surface to
54°-5 at 30 feet.

Loch an Tairbeirt Stuadhaich (see Plate LXX.). — An insignificant little
lochan, through which the overflow of Loch Deoravat passes to Loch a'
Bhuird and Loch Scadavay. Though only a quarter of a mile long, and
very narrow, the loch is of some interest. Its outline is cruciform.
The shores are ranges of vertical cliffs, similar to those of the adjacent arm
of Loch Scadavay. The height of the surface above sea-level is 21*15 feet,
or 2J feet higher than Loch a' Bhuird.

Loch a' Bhuird (see Plate LXX.). — This loch is entirely similar to
Loch. Scadavay, from which it is only cut off by a narrow barrier. It is
fully three-quarters of a mile long, by one-third of a mile in greatest
breadth. It consists of two portions, elongate from west to east, connected
by a channel at the west end. The southern portion has an east and
a west expansions connected by a very narrow strait, from 4 to 9 feet deep.
The western expansion is shallow (deepest 18 feet), and filled with stones
and small islands. One of these is of the horseshoe shape, examples of
which are found in Lochs Scadavay and Fada. The eastern expansion is
shallow (9 or 10 feet) in the middle, but depths of 22 to 25 feet are found
close to shore. The northern portion is a narrow triangle of fair depth,
with the maximum of 36 feet about the centre. The shores are rocky.
There was a range of temperature of 8J° from surface to bottom on
May 31, 1904:—

THE FRESH-WATER LOCHS OF SCOTLAND. 187

Surface 61°-0 Fahr.

15 feet 54°-4 „

25 „ 52°-8 „

35 „ 52°-5 „

Loch Huna (see Plate LXXI.). — The uppermost loch of the Scadavay
basin, and the highest, being 21*6 feet above sea-level. In outline it is less
irregular than most Uist lochs, and somewhat resembles Loch Hunder in
form. It is nearly a mile long and half a mile broad. The bottom is very
uneven, and there are many small islands. On one of the largest there is
a Dun, and a long causeway leads to the west shore. The loch is on the
whole very shallow. There is a hole 23 feet deep in the northern part,
and another, with the maximum depth of 25 feet, in the southern part.
Many boulders are scattered around, as well as in, the loch. The shores
are partly of rock, partly of mounds of gravel.

On May 31, 1904, there was a difference of 6^D between the surface and
bottom temperatures : —

Surface 64°-0 Fahr.

5 feet 61°-0 „

10 „ 60°-0 „

20 „ 57°-5 „

Loch na Moracha (see Plate LXXI.). — A loch of somewhat simple
form, draining, through a barrier a few yards wide, into Loch nan Eun.
From the north end three narrow inlets diverge to north and east and
west. In these are some islands. The body of the loch has no islands
except close inshore, and is a simple basin. The 10-feet contour follows
the outline, but is closer to the shore on the north-east, showing that the
slope is steeper there. Within are two depressions: 19 feet near the
north end, and 20 feet near the south-east corner. The greater part of the
shore is of rock. The temperature on May 11, 1904, was nearly uniform
throughout, viz. 49°-2 Fahr. at the surface, and 49°'0 at 15 feet.

Loch nan Eun (see Plate LXXI.). — In length Loch nan Eun is
exceeded only by Loch Obisary and Loch Scadavay. Many lochs exceed
it in area and volume. It is a narrow loch, running from west to east,
and measures 2| miles in length, by half a mile in greatest breadth.
As the centre of the loch at the broadest part is occupied by a large
island, Eilean Buidhe, half a mile long, there is no breadth of open water
anywhere. The mean depth is only 8 feet, and, as in Loch Scadavay, the
deeper soundings, 31 feet, 20 feet, 24 feet, etc., were obtained in isolated
holes. The superficial area is half a square mile, and the volume of water
114 millions of cubic feet. The loch drains an area of 4 square miles,
which includes Lochs Huna and na Moracha. Besides Eilean Buidhe
there are many smaller islands, and innumerable stones obstruct the
channel, especially in the western part and to the south of Eilean Buidhe ,
where it is difficult to get about in a boat.

188 BATHYMETKICAL SURVEY OF

Our gillies said that the overflow of Loch Huna enters near the west
end, but there was no stream when we visited it. A stream, a few yards
in length, comes in on the south from Loch na Moracha. A short stream
flows from the east end into Loch Scadavay. Rock is exposed at frequent
intervals all round the shore, as well as on the larger islands.

The temperature on May 11, 1904, was 51°*U Fahr. both at the surface
and at 15 feet.

Loch Scadavay (see Plate LXX.). — There is probably no other loch in
Britain which approaches Loch Scadavay in irregularity and complexity of
outline. It is an extraordinary labyrinth of narrow channels, bays, pro-
montories, and islands. Though it measures 4*- miles in length, from
north-west to south-east, and about 2 miles in greatest breadth, from
south-west to north-east, there is really no broad open water in the whole
loch, the broadest part being in the westernmost inlet, where there is open
water half a mile broad. The ratio of circumference to length will
illustrate how very irregular is the form — though only a little over 4
miles in length, a rough measurement indicates a shore-line of 50 miles.
Very many islands stud the surface, the largest being nearly a mile in
length. The main road round the island now cuts Loch Scadavay into
two parts, which are connected by such a small channel under the road that
in time of flood the south loch may temporarily rise some feet higher than
the other, though normally they are at the same level. There is nowhere
any considerable depth, the deepest parts occurring as little holes, while
the narrows are usually shallow. A lowering of the surface by no more
than 6 feet would divide the loch into a dozen small lochs, and a host of
little ponds, while a rise of the same amount would vastly increase its
area by including all the higher lochs in the same basin, among them
such large lochs as nan Eun, Huna, a' Bhuird, and Deoravat. The deepest
holes are 50 feet in the south loch, and 37 feet in the north loch.

The small superficial area is in remarkable contrast to the great shore-
line, both portions together measuring only 1| square miles. The mean
depth, also, is very low, being only about 9 feet. The narrow channels
leading into some of the elongate arms are often only from 1 to 2 feet in
depth. Some of the islands have been the sites of Dims, and these have
been connected with the shores by narrow causeways. The volume of
water is only 418 millions of cubic feet. One other loch in North Uist
has a greater volume, though of less superficial area, Loch Obisary having
about twice the volume. In the shallower parts numerous stones and
boulders project above the surface, rendering navigation difficult even in a
small rowing-boat. In several instances we were unable to complete lines
of soundings from this cause. The shores are in parts of peat, in other
parts of stones, or gravel with boulders, but rock appears in many parts.
The easternmost arm of the south loch, one-sixth of a mile in length, has
precipitous rocky cliffs on both sides. This character is continued in the

THE FRESH-WATER LOCHS OP SCOTLAND. 189

little Loch an Tairbeirt Stuadhaich, which is only separated from this
arm of Loch Scadavay by a narrow ridge.

Two very short streams enter Loch Scadavay, conveying the overflow
of Lochs nan Eun and a' Bhuird, with the higher tributary lochs. The
Garbh-Abhuinn, the most considerable stream in this part of the island,
flows eastward from the north portion of the loch to Loch Garbh-
Abhninn, which drains through Lochs Skealtar and nan Geireann into
Loch Maddy.

When surveyed on May 24 to 30, 1904, Loch Scadavay was 16' 15 feet
above sea-level; the Ordnance Survey found it to be 16'8 feet on June 11,
1875.

A series of temperatures taken in the deepest part, May 30, 1904,
showed a total range of 11°. The temperature at 25 feet was only 00>6
higher than at the bottom, while from 25 feet to 10 feet there was a rise of
4°-4, and from 10 feet to the surface of 6°'0 :—

Surface 63°-0 Fahr.

10 feet 57°-0 „

25 „ 52°-6 „

50 „ 52°-0 „

Loch na Garbh-Abhuinn (see Plate LXXII.).— A small loch (locally
known as Upper Skealtar), about one-third of a mile long by a quarter
of a mile broad. It is divided into two nearly equal portions by pro-
montories which nearly meet. The northern half has a depression
towards the east end, with a maximum of 20 feet. The south half is
entirely shallow, the deepest part only 7 feet. The strait between is only
4 feet deep.

Loch na Garbh-Abhuinn Ard (see Plate LXXII.).— In flood this is part
of Loch na Garbh-Abhuinn, but when we visited it there was a strong
current through the narrow part, though we could detect no difference of
level. This loch is so shallow that a boat can with difficulty get about
in it. An island occupies the middle of it. In fact, these two lochs are
only expansions of the river leading from Loch Scadavay to Loch Skealtar.

Loch SJceaUar (see Plate LXXII.). — A fairly large loch, nearly a mile
in length by half a mile in greatest breadth. It is of irregular outline,
and has many islands, but is nevertheless a simple basin. The contours
are affected by the islands, so that they do not follow the shore. The
deepest part, with the maximum of 42 feet, is in the middle of the loch,
between two islands. There is a second little depression of 40 feet a
little further west. The burn from Loch Garbh-Abhuinn, one-sixth of
a mile long, enters on the west. The outflow is by a little loch, which
was not sounded, leading to Loch nan Geireann. Loch Skealtar was
8*75 feet above sea-level on May 9, 1904; the Ordnance Survey found it
to be 8'5 feet on June 12, 1875.

190 BATHYMETRICAL SURVEY OF

When surveyed, the temperature was uniform, 47°-7 Fahr., from
surface to bottom, following on a gale of three or four days' duration.

Loch nan Geireann (see Plate LXXIL). — A little tidal loch near
Lochmaddy, the lowest of the Scadavay basin. It is about two-fifths of
a mile long by one-fifth of a mile broad. In form it is oblong, with an
arm running towards Loch Skealtar. There are some small islands, and
the bottom has many large boulders scattered over it, some of which
project above the surface. It is a simple basin, but the contours are
irregular, and do not closely follow the shore-line. The maximum depth
is 31 feet. The stream entering from Loch Skealtar has no appreciable
length, there being merely a fall of a foot from a little loch intervening
between Lochs nan Geireann and Skealtar. The outflow is a drain under
the road into Loch na Ciste, a sea loch. The fauna was that of fresh water.
Only high tides come in and raise the surface from 1 to 1J feet. The
height above sea-level, on May 9, 1904, was 7'45 feet. The temperature
at the surface was 49°'0 Fahr., and at 25 feet only £° less.

The Strumore Basin. — This comprises a chain of three lochs, of which
Loch an Strumore (tidal) and Loch Fada (fresh) were surveyed, while the
intermediate little Loch Galtarsay was not sounded.

Loch an Strumore (see Plate LXXIL). — Loch an Strumore (or Loch
an Aastrom) is a pretty large tidal loch of oblong form, situated about
a mile north-west from Lochmaddy. It is a little more than a mile long,
and half a mile in greatest breadth. The outline is irregular, with
many little inlets. There are many islands, the largest near the middle,
where the loch is much constricted, and lying close to the north shore.
Rock and stones alternate on the shore. The bottom is almost level,
about 12 feet deep in the central parts, the bays shallower. There is a
deeper hole at the east end, near the outflow, with the maximum depth
of 22 feet. Ordinary tides enter, and the loch is filled throughout with
fucoids, but juncus also grows abundantly. Level on May 10, 1904,
when the tide was out, 3*7 feet above the sea. The temperature at the
surface was 490>2 Fahr., and at 18 feet 47°-2.

Loch Fada (see Plate LXXIL). — Loch Fada consists of two portions
connected by a narrow channel. The north portion is narrow and elon-
gate from west to east. It is studded with islands, on which large numbers
of gulls and other birds nest. The greater part of it is less than 1 0 feet
in depth. The maximum depth of 26 feet is found close to an island at the
east end. There is also a very narrow channel, with depths up to 25 feet,
between the peninsula called Ard Fhada and a chain of small islands.
The southern portion of the loch is triangular. It is one of the largest
bodies of open water on the island, but even here there is a heap of stones
projecting above the surface almost in the centre of the triangle. There

THE FRESH-WATER LOCHS OF SCOTLAND. 191

are two holes 45 feet deep, one to the south-east, the other to the south-
west, of this heap of stones. The shore and the islands are entirely of rock,
except at the east end near the outflow, where there are some mounds of
gravel. The total length of the loch is fully If miles, and the greatest
breadth a little under a mile. The superficial area, two- thirds of a square
mile, is about equal to that of Loch Geireann Mill, and is only exceeded
by Lochs Scadayay and Obisary. The volume of water is 199 millions of
cubic feet. The mean depth is 10 feet.

Loch Fada has a very small drainage area, 3J square miles, and
receives only small local burns. The outflow is by a very short stream
into Loch Galtarsay, whence a river half a mile in length leads into
Loch an Strumore. The height above sea-level on May 21, 1904, was
29-85 feet.

Loch Veiragvat (see Plate LXXIL). — A small loch to the north of
Loch Fada. It measures fully half a mile in length by a quarter of
a mile in greatest breadth. It is of roughly triangular form, broadest
towards the east end. The outline is simple, little indented. There are
several islands, the largest near the centre ; and many boulders appear
above the surface at the west end. The islets at the east end are of rock,
and rock also appears at a few points on the north shore, and at the west
end. The large island is low and grassy, and formed of stones. The
bottom is uneven, the greater part of it covered by less than 10 feet of
water. The maximum depth of 25 feet occurs in a small hole between
the island and the north shore. Loch Veiragvat is the highest loch
surveyed in North Uist. Its height on May 12, 1904, 71-85 feet above
the sea, is twice that of Loch a' Chonnachair, the next in elevation. The
temperature at the surface was 49°-3 Fahr., and at 10 feet 49°-0.

Loch an Duin (see Plate LXXIII.). — A tidal loch of exceedingly
complex form, consisting of five principal expansions, elongated from east
to west, with many lesser inlets and numerous islands. It is nearly a
mile long, and two-thirds of a mile in greatest breadth. Some of the
branches could not be entered. All are shallow, mostly less than 7 feet
deep, except the northern expansion, which is on the whole shallow, but
having a hole where the maximum depth is 35 feet. There are two Duns,
from which the loch takes its name, one in the northern branch, another,
very well preserved, in the southern expansion. The shores are of rock
covered with peat. The two lowest basins communicate separately with
the sea, and are filled with Fucus, Zoster a, etc. The uppermost basin
is very slightly salt, and fresh-water plants (Myriophyllum) grow in it.
The level of the loch on May 20, 1904, was 4'5 feet above the sea, and
there was no difference of level between 10 a.m. and 5 p.m. The tempera-
ture at the surface was 52°'5 Fahr., at 15 feet 52°-0, and at 35 feet
50°-5.

192 BATHYMETRICAL SURVEY OF

Loch nan Geireann (see Plate LXXIV.). — As there are two lochs of
the same name, this, the larger one, is locally distinguished as Geireann
Mill. The stream from the loch formerly supplied a mill, now in ruins.
Though one of the largest lochs on the island (it comes fourth ia point
of length), Loch nan Geireann is so generally similar to Loch Scadavay
that a very short description will suffice. It is 2 miles in length and
three-quarters of a mile in greatest breadth. Unlike Lochs Scadavay and
nan Eun, the bottom is even, and there are no deep holes, though many
small islands and numbers of large stones project above the surface. The
area is two-thirds of a square mile, and the volume 121 millions of cubic
feet. The maximum depth is 18 feet, and the mean depth 6 feet. The
shores are almost everywhere of rock, though there are some stony stretches.
The rock is in places covered with deep peat and heather ; there are many
boulders scattered around, and some perched blocks. There are many
bays with white sand, and a great part of the bottom is sandy. The
distribution of the sand under the influence of wind probably accounts
for the filling up of holes and the general uniformity of the bottom. The
short stream conveying the overflow to the sea has a rocky channel. The
drainage area extends to 6J square miles, and includes some small lochs
which were not surveyed. The principal streams enter on the west.
The loch was surveyed on May 16 to 19, 1904, when the level was found
to be 16-4 feet above the sea; on September 23, 1875, the Ordnance
Survey found it to be 17 '3 feet. The temperature on May 19 was 52°'0 Fahr.
at the surface, and 51°-5 at 10 feet.

Loch Hosta (see Plate LXXIIL). — A small loch in the extreme west
of the island. It is of oblong form, half a mile in length by fully a
quarter of a mile in greatest breadth. It differs from most of the other
lochs in having a simple little-indented outline. The basin is simple,
the sides sloping gently all round, but a little more steeply on the north-
east side, to the maximum of 31 feet nearly in the centre. On June 18,
1904, the surface was 23'5 feet aboye sea-level; on September 11, 1875,
the Ordnance Survey found the level to be 23'0 feet. A small burn, half
a mile long, runs west to the sea at Raikinish.

LocJi Oban aj Chlachain (see Plate LXXV.).— A small tidal loch,
nearly a mile long by a quarter of a mile broad, draining into the Sound
of Monach, opposite the island of Baleshare. It runs from west to east
towards the head of Loch Eport, which it so nearly approaches that the
island is almost cut across, the isthmus being less than a quarter of a mile
across. The loch consists of a narrow western part, filled with seaweeds,
and a triangular eastern part, with an almost level bottom about 14 feet
deep, the maximum of 19 feet being recorded close to the south shore.
The tides affect the level more than in the other tidal lochs sounded.
On June 1, 1904, the level of the surface was 3' 75 feet above the sea, and

THE FRESH-WATER LOCHS OP SCOTLAND. 193

the temperature of the water was found to be uniform, readings *at the
surface and at 15 feet being identical, 61°'0 Fahr.

Loch Leodsay (see Plate LXXV.). — A small tidal loch lying just south
of Loch Oban a' Chlachain. It is nearly two-thirds of a mile long by
a quarter of a mile broad, of very irregular form, with a large western
and smaller eastern expansions. The west portion is very shallow, and the
greatest depth, 17 to 20 feet, is in the narrow channel between the two
expansions.

The Creige Leithe Basin. — This basin includes only two lochs, the
lower one, Loch na Creige Leithe, very small; the upper, Loch nan
Garbh Chlachan, much larger. The basin opens into Loch nan Gealag,
a branch from the strait between Uist and Grimsay.

Loch nan Garbh Chlachan (see Plate LXXV.). — A small rhomboid
loch, from which a number of narrow inlets branch off. It is barely half
a mile long by a quarter of a mile broad. The shores are of rock, and
it is filled with larger and smaller rocky islands and boulders. It is all
shallow, except in the open water east of the principal islands, where there
is a depth of 25 feet. The surface on June 9, 1904, was 15'2 feet above
the sea. The temperature was 61°'0 Fahr. at the surface and at 25 feet.

Loch na Creige Leithe (see Plate LXXV.). — A narrow loch, only a
quarter of a mile long, with rocky shores. It is at the same level as
Loch nan Garbh Chlachan, being only separated by a bar of stones. The
maximum depth is 14 feet.

Loch an Tomain (see Plate LXXVI.).— A typical Uist loch, with its
complexity of form, being almost cut into a number of lochs by narrows
and islands. It is nearly 1J miles in length and one- third of a mile in
extreme breadth. The western of the four chief basins has a maximum
depth of 36 feet, the middle basin 37 feet, the eastern basin 31 feet, and
the north-eastern basin 44 feet, the maximum depth of the loch. . The
loch on June 23, 1904, was 14' 15 feet above the sea. It drains by a
small stream one-third of a mile long into the Little Minch. The shores
are steep and rocky on all sides.

The Crogavat Basin. — There are only two lochs in this basin — the
lower, Loch Crogavat, connected by a short stream with the Little Minch ;
the upper, Loch a' Ghlinne-Dorcha, the second deepest loch on the island.

Loch a' Ghlinne-Dorcha (see Plate LXXVI.).— A dark little loch,
occupying the whole of the east flank of Burrival (461 feet high). It is
half a mile long by one-third of a mile broad, covering an area of 50 acres,
and is divided into two portions by a constriction. The northern part is
occupied by a large island. In this part the deepest sounding is close

194 . BATHYMETRICAL SURVEY OF

under the cliffs on the north, where there is a depth of 36 feet. The
southern half is a simple basin, free from islands, with fairly steep slopes
on all sides, and a maximum depth of 85 feet in the centre. The mean
depth of over 27J feet is the greatest in the Uist lochs. The shore is
entirely steep and rocky, forming cliffs under Burrival, and on the north
a burn a few yards in length leads to Loch Crogavat.

The surface on June 25, 1904, was 23-2 feet above sea-level. There
was a difference of 6° between the temperature at the surface and at the
bottom : —

Surface 55°-0 Fahr.

25 feet 55°-0 „

50 „ 54°-5 „

70 „ 50°-4 „

85 „ 49°-0 „

Loch Crogavat (see Plate LXXVL). — Loch Crogavat lies to the south
of Loch Eport, near its mouth. It approaches at both ends within a few
yards of Loch Eport, but it drains eastward into the Little Minch. It
is over a mile long, by a quarter of a mile broad, and covers an area of
about 84 acres. In general form it is dumb-bell shaped, narrow in the
middle and expanded at each end. In the western half is a large island.
There is deep water on both sides of this island, depths of 40 feet occur-
ring in the narrow channel to the north of it, as well as in the broader
part on the south. The eastern basin is larger, of oblong form, with
many small islands. The maximum depth is 55 feet. The channel
connecting the two basins is also deep, ranging from 37 feet to 45 feet.
The mean depth, 24 J feet, is relatively high, being only exceeded by
Lochs Obisary andfra' Ghlinne-Dorcha. The shores and islands are
entirely of rock. The temperature on June 25, 1904, was uniform
throughout, viz. 55°-2 Fahr. at the surface, and at the depths of 25 and
50 feet. Loch Crogavat is less than a foot lower than Loch a' Ghlinue-
Dorcha, standing 22'45 feet above sea-level.]

Loch Obisary (see Plate LXXVL).— The largest loch in North Uist,
measured by the volume of water, which amounts to 837 millions of cubic
feet, or twice that of Loch Scadavay. It is also by far the deepest loch
on the island, the maximum depth of 151 feet being nearly twice that
of Loch a' Ghlinne-Dorcha, the second deepest. Loch Scadavay, however,
is longer, and has a greater superficial area.

Loch Obisary lies at the foot of Eaval, the highest hill in North Uist
(1138 feet), which it half encircles, its shores following the curve of the
mountain on the north and west. It is roughly crescent-shaped, and
measures 2\ miles in a straight lino between the points of the crescent,
or over 3 miles following the axis of maximum depth. It is broadest
in the northern part, where it measures over one mile across. There are,
however, large islands in this part of the loch, so that the broadest open

THi: FRESH-WATER LOCHS OF SCOTLAND. 195

water is reduced to about half a mile. The outline is extremely irregular,
and there are many islands large and small. The northern part of the
loch is somewhat triangular, but its centre is filled by three large islands,
the largest of which, Eilean Leathann, is fully half a mile long.

As in Loch Scadavay, there are many distinct depressions, separated
by shallows. In each of these there is considerable depth. In the
narrow part, west of Eaval, there are three basins with maxima of
51, 57, and 50 feet respectively. South of Eilean Leathann is a basin
with a depth of 65 feet, and east of the same island one of 58 feet. North
of Eilean Leathann is a depth of 48 feet. Between Eilean Mor and the
stream flowing out to the north into Loch Eport lies the deepest basin
in the loch. It is of very limited extent, measuring only about a quarter
of a mile each way, between the islands and the shore, but has the
remarkable maximum depth of 151 feet. To the west of this is another
very small triangular area, having a depth of 70 feet. The mean depth
of 25f feet is less than that of Loch a' Ghlinne-Dorcha, and a little more
than that of Loch Crogavat, The greater part of the shore is of rock,
forming on the west a range of cliffs, with some small stretches of gravel,
stones, and peat. Immediately under the north slope of Eaval is the
largest stretch of peat-covered gravel, extending about a mile without
any exposed rock. The large islands, and most of the small ones, are
of rock. On Eilean Leathann mounds of stony debris lie over the rock.
The level was ascertained on June 15, 1904, by measuring from Loch na
Ceithir-Eileana to be 8*2 feet above the sea.

Loch Obisary is tidal. Though the surface level is little affected by
the tides, these enter often enough to render the water quite salt, and to
permit numerous marine animals to live in it. Mussels (marine) were
found adhering to the fresh-water weeds, and marine Crustacea abounded
among the weeds. Large beds of a slender grass-like plant, which
appeared to be Juncus sujjinus, but was not in flower, reached the surface
from depths of from 14 to 18 feet. From the deepest part a black gritty
mud was obtained.

A series of temperatures was taken in the deep hole at noon, June 25,
1904. There was a range of 8' '3, and a remarkable inversion was indicated,
the thermometer at 50 feet reading 1" lower than at the bottom. The
readings at 50 feet and 100 feet were repeated, after testing by again
reading the surface temperature, and were consistent with the first
readings : —

Surface (repeated) 55°-5 Fahr.

10 feet 55°-5 „

25 „ 50?-4 „

50 „ (repeated) 47^2 „

100 „ (repeated) 48°-2 „

150 „ 48°-2 „

Loch a1 Chladaich (see Plate LXXV.j. — A very small narrow loch on

196 BATHYMETKICAL SURVEY OF

the south shore of Loch Eport, between the Oban nara Fiadh basin and
Loch Obisary. It is nearly one-third of a mile long and one-eighth of
a mile in greatest breadth. It is one of the highest lochs surveyed, being
27'95 feet above sea-level on June 7, 1904. It is very shallow, the
maximum depth being 9 feet. It drains north into Loch Eport by a
short burn.

The Oban nam Fiadh Basin. — This comprises seven lochs, of which
the lowest, Oban nam Fiadh, is purely tidal; while Loch Caravat, the
largest loch of this basin, is very slightly brackish. Two chains of lochs
connect with Loch Oban nam Fiadh. On the east Loch na Coinnich,
communicating with Loch na Ceithir-Eileana, and on the south Loch
Caravat. West from Loch Caravat lies Loch an lasgaich ; east from it
Loch 'ic Colla, connected with which is Loch an t-Seasgain.

' Loch Oban nam Fiadh (see Plate LXXV.) . — This loch is of unusual form
among the lochs of North Uist. It is elongate and narrow, over a mile
long by a quarter of a mile in greatest breadth, and with a mean breadth
of one-eighth of a mile, covering an area of about 92 acres. It is divided
into three portions by narrows. The main part is of oblong form, its axis,
east and west, two-thirds of a mile long. There are several small islands,
one in the centre of the loch. The bottom is uniform, 5 or 6 feet in depth,
but with two depressions of 10 feet. The middle and upper portions are
small, and 4 to 5 feet in depth. They are separated by a low island, and
the whole channel here is grown up with reeds. The stream from Loch
Caravat enters the upper basin. The shores are of rock.

The loch is interesting from the transition it shows from salt to fresh
water, and the corresponding difference in the fauna and flora of the upper
and lower basins. The lower part is purely tidal. If not filled by all
ordinary tides, it is, at any rate, so frequently filled as to enable sea-weeds
to grow and marine animals to live. Yet fresh- water plants also grow in
this part, and mussels are found adhering to these. The very narrow
channel and the dense growth of Phragmites prevent the tides from having
much effect on the upper portion in summer. Here the water tastes
almost fresh, and such fresh- water Crustacea as Holopedium are found.
Yet high tides must raise this part considerably, as Loch Caravat, at the
time of our visit 2 feet higher, is filled through *it. The temperature at
the surface was 68°'0 Fahr., and at 6 feet 66°'8, on June 7, 1904.

Loch Caravat (see Plate LXXV.). — Loch Caravat is the second deepest
among the larger lochs of the island, though the little Loch a' Ghlinne-
Dorcha is somewhat deeper. In general form it resembles the letter H,
there being two narrow portions running east and west, connected by
a narrow channel running nbrth and south. In these circumstances it is
difficult to define length and breadth ; a line drawn from the west end of

THE FRESH-WATER LOCHS OF SCOTLAND. 197

the northern branch along the connecting Urm, to the east end of the
southern branch, would be about 2 miles in length. The northern branch,
nearly lj miles in length, is divided into three portions. That in the east,
adjoining the outflow, is quadrate, measuring about a quarter of a mile
each way ; it has an even bottom, with a greatest depth of 20 feet. The
middle portion is filled with islands, on one of which, Dim Scor, is a Dun.
Another, Eilean Dubh Dun Scor, is connected with a larger island on the
east by a long causeway. Among these islands the north branch is deeper
than elsewhere, the greatest depth being 30 feet. The west portion of
this branch is three-quarters of a mile long, and very narrow and shallow,
having a greatest depth of only 1 1 feet. It is separated from the central
part by a large island, connected with the north shore by a causeway, and
having the channel on the south full of stones, and from 1 to 3 feet in
depth. The burn from Loch an lasgaich enters the west end of this arm.
The narrow passage connecting the northern and southern branches of the
loch is shallow in the middle and northern portions, but towards the south
it rapidly deepens into one of the basins which form the southern half of
the loch. The southern branch of the loch is shorter than the northern,
measuring little more than one mile in length, but it is much broader and
very much deeper. It contains two distinct basins, the best marked basins
in the island, separated by a strait filled with large islands.

The west basin is triangular, three-quarters of a mile long by one-third
of a mile broad. Though the island, on which is the Dun Ban, lies well
out from the shore, it does not destroy the simplicity of the basin. The
slope of the bottom is steeper on the south side, more gradual on the north.
The deepest sounding in this basin, 50 feet, occurs near a small island at
the east end of the basin. The east basin is smaller but deeper. It is
fully half a mile long l^y a quarter of a mile broad. Its axis runs north
and south. The contours are more indented than the outline, owing to the
presence of a number of submerged promontories. The slopes of the
bottom are about equal on all sides, and the deepest part (maximum
sounding of the whole loch, 74 feet) is about the middle of the basin.
The narrows between the east and west basins is nearly closed by islands,
of which Eilean Dubh, one-sixth of a mile long, is the largest. There are
three narrow channels among these islands with depths of only 5 or 6 feet.
Large portions of the shores are stony, but rock is exposed in many places,
and the principal islands are of rock. The stream flowing out of the
north-east corner into Loch Oban nam Fiadh, is one-eighth of a mile long,
and has a fall of 2 feet. At the south-east corner the burn from Loch 'ic
Colla flows in. The superficial area of Loch Caravat is about 374 acres,
or over half a square mile. The drainage area, which includes Lochs an
lasgaich, 'ic Colla, an t-Seasgain, and some smaller lochs, has an extent of
fully 3 square miles. By volume of water, which amounts to 270 millions
of cubic feet, Loch Caravat is the third largest loch in the island. When
surveyed on June 8, 1904, the height of the surface above sea-level was

198 BATHYMETRICAL SURVEY OF

7'2 feet. If there be no error in this measurement the tide must some-
times enter the loch, and the local gillies stated that this was so. Never-
theless the water is fresh enough to be drunk, and maintains the usual
fresh-water fauna. Through so many narrow and shallow channels it is
probable that the tides can have Jittle effect on the salinity of the more
distant parts of the loch.

On June 11, 1904, there was a difference of 7°-6 between the surface
and the bottom temperatures. The great part of the difference, 40>5,
occurred between 35 and 40 feet, as shown in the following table : —

Surface 58°'8 Fahr.

25 feet 57°'2

35 „ 56c-8

40 „ 52°-3

50 „ 51°-2

72 „ 51°-2

Loch an lasgaich (see Plate LXXV.). — A little loch lying west from
Loch Caravat and draining into it. It is fully half a mile long, by a
quarter of a mile in greatest breadth. It is of the usual irregular outline
and uneven bottom, and is studded with small islands. A great part of it
is less than 8 feet deep, and the maximum of 1 6 feet is quite close inshore
towards the east end of the loch. The surface is 11*2 feet above sea-level.

LocJi 'ic Colla (see Plate LXXV.). — An extremely irregular loch
(locally called Loch McColl), consisting of several narrow arms almost cut
off from one another. It is a mile long, by half a mile in greatest breadth.
The south portion has an uneven bottom, the deepest sounding in the loch
(34 feet) having been taken near the island towards the east end, and
a depth of 26 feet occurs close to the east end* The north portion has
a fairly deep basin at its west end, where the maximum depth is 33 feet.
A lesser basin of 22 feet in depth lies to the east of this. Loch 'ic Colla,
on June 9, 1904, was 16*1 feet above sea-level. Eock is seen at intervals
all round the shore, but the stream, about 75 yards long, flowing into Loch
Caravat, has a stony channel.

In the deep part the range of temperature from surface to bottom was
nearly eight degrees, which occurred between the depths of 25 and 33 feet,
the readings at the surface and at 25 feet being identical —

Surface... .'. 60°-2 Fahr.

25 feet 60°'2 „

33 „ 52°-3 „

Loch an t-Seasgain (see Plate LXXV.). — An insignificant narrow strip
of water, partly choked with weeds, lying south from Loch 'ic Colla.
Though distinguished by a name* of its own, it was at the same level as
Loch 'ic Colla, and really forms part of it. The maximum of 18 feet is
found in a little hole at the east end.

THE FRESH-WATER LOCHS OF SCOTLAND. 199

Loch na Ceithir-Eileana (see Plate LXXV.).— The higher of the two
lochs of this basin which lie between Loch Oban nam Fiadh and Loch
Obisary. It is of somewhat simple outline among the lochs of Uist, and
somewhat rhomboid. It is half a mile long by one-third of a mile broad.
The bottom is uneven, and, as the name implies, four islands rise above
the surface. The two larger islands are on a ridge which runs south-west
and north-east, the depths between them and the shores varying from 7 to
9 feet. In the basin east of them, of triangular form, the maximum depth
of 42 feet occurs quite close to the shore at the east end, and another
sounding of 39 feet is close inshore on the south. West of the larger
islands is a deep furrow, where a depth of 37 feet was found. This is the
highest loch in the Oban nam Fiadh basin, the surface being 16'85 feet
above sea-level on June 7, 1904.

The range of temperature was great, amounting to 12°*6 throughout
the body of water, the greatest fall being observed between 20 and 25 feet,
— a fall of 5", or one degree per foot of depth, as shown in the following
table :—

Surface 64°-6 Fahr.

5 feet 63°-0 „

15 „ 61°-0 „

20 „ 58°-0 „

25 „ 53^-0 „

35 „ 52^-0 „

Loch na Coinmch (see Plate LXXV.). — A little triangular loch, half
a mile long, between Loch na Ceithir-Eileana and Loch Oban nam Fiadh.
The shores are of rock and the bottom stony. The bottom is very uneven,
and the maximum depth of 25 feet is found in the centre of the loch, close
to and between two heaps of stones. The surface on June 7, 1904, was
only 9-9 feet above sea-level. The range of temperature was here also
very high, nearly 16 degrees in the 25 feet of water, the fall between
15 and 20 feet exceeding one degree per foot of depth, as shown in the
accompanying table : —

Surface 68°-0 Fahr.

10 feet 63°-0 „

15 „ 62°-6 „

20 „ 57°'0 „

25 „ 52°-3 „

Loch Tormasad (see Plate LXXI.). — A narrow and shallow loch,
measuring two-thirds of a mile long by one-third in greatest breadth,
which lies just west of the head of Loch Eport, into which it drains by
a burn half a mile in length. The southern part forms an equilateral
triangle, the centre of which is occupied by a low island, joined to the
shore by a causeway. The bottom is nearly level, about 7 feet deep, with
depressions of 9 and 10 feet.

200 BATHYMETRICAL SURVEY OF

Locli a1 Bharpa (see Plate LXXL). — A locb draining into the head
of Loch Eport, between Lochs nan Eun and Tormasad. It is fully a mile
long, by nearly half a mile in greatest breadth. The western half is
narrow and shallow, with several narrow inlets. The eastern half is
expanded and forms a simple basin of some depth. The 10-feet and
20-feet contours follow the shore-line. The area over 30 feet in depth is
narrow, occupies the centre of the loch, and is divided into two parts, with
maxima of 35 and 37 feet.

Loch a' Buaille (see Plate LXX.). — Loch a' Buaille, on the north side
of Loch Eport, between that loch and Loch Scadavay, is half a mile long,
but exceedingly narrow. It is shallow on the whole, but depths occur of 14
feet near the south end, and 23 feet (the maximum) near the north end. It
drains south, through a smaller loch, into Loch Eport. The surface on
June 4, 1904, stood 20-35 feet above the sea. The range of temperature
was unusually high, amounting to 14J° in the 20 feet of water, the fall
between the depths of 15 and 20 feet exceeding 7° — a fall of nearly lj°
per foot of depth, as shown in the following table : —

Surface 67°'0 Fahr.

5 feet 65°-5 „

10 „ 62°-5 „

15 „ 59°-6 „

20 „ ... 52°-5 „

Loch Tarruinn an EitJiir (see Plate LXX.). — A loch of very irregular
form, lying between Loch Eport and the southern extremity of Loch
Scadavay. It is half a mile in length by one-third of a mile in greatest
breadth, and consists of a number of very narrow branches of little depth-
The widest part, in the north, has a heap of stones in the centre. In this
part the maximum depth of 23 feet is found. The principal islands are of
rock, the shores of rock, mounds of gravel, boulders, and peat. The
loch drains directly by a stream some 50 yards long into Oban Sponish,
a branch of Loch Eport. The surface on June 4, 1904, was 16*1 feet
above sea-level. The temperature had the high range of 14J°, as in
Loch a' Buaille, and here also the greatest fall was observed between 15 and
20 feet, viz. 6°, rather less than in Loch a' Buaille, but still exceeding 1°
per foot of depth : —

Surface 66°-7 Fahr.

10 feet 61°-5 „

15 , 58°-2 „

20 „ 52°-3 „

The Hunder Basin. — This also contains only two lochs which were
surveyed, Lochs Hunder and a' Chonnachair. The lower loch is joined to
a branch of Loch Eport on its north side.

Loch a' Chonnachair /see Plate LXXVIL), though draining through
Loch Hunder into Loch Eport, is situated close to Lochmaddy. It is of

THE FEESH- WATER LOCHS OF SCOTLAND. • 201

the usual irregular form, consisting of a number of narrow branches,
separated by conspicuous promontories, and contains several small islands.
It is shallow, with a few deeper holes, with depths of 25 feet in the south
portion, and 27 feet (the maximum) in the north portion. It is fully half
a mile in length. On June 3, 1904, there was a difference of 8°*4 between
the temperature at the surface and that at 25 feet, a fall of no less than
0-4 being observed between 15 and 20 feet : —

Surface 60°-4 Fahr.

15 feet 59°-4 „

20 „ 53°-0 „

25 „ 52°-0 „

Loch Hunder (see Plate LXXVII.). — Loch Hunder lies on the west
flank of the South Lee, as Loch Obisary lies at the foot of Eaval. It is 1 J
miles long by two-thirds of a mile in greatest breadth, and nearly a quarter
of a mile in mean breadth. The outline, though much indented, is simpler
than usual in the lochs of Uist. It is more like a valley loch, but the
presence of many islands indicates that it is not a simple basin. These
islands divide the loch into three distinct basins. The northern basin is
cut off from the middle basin by two large islands, the larger of which is
joined by an artificial causeway to the east shore. It has a maximum
depth of 38 feet. In the passage between the island and the west shore
the minimum depth is 7 feet. The middle basin contains the maximum
depth of the whole loch, 60 feet. It is separated from the southern basin
by a chain of three islands. The middle one, called Dim Ban, is in the
centre of the loch, and has fairly deep water both to the east and west.
The eastern island is connected with the shore by a causeway, and close to
it, on a smaller island, is a large Dim. Between the middle island and the
western one is a depth of 34 feet. The southern basin has a depth of 55
feet, a short distance south of Dun Ban. The volume of water in Loch
Hunder is 146 millions of cubic feet. The superficial area is about 185
acres, or fully a quarter of a square mile. The drainage area of 2^ square
miles includes Loch a' Chonnachair, which is a quarter of a mile distant, the
stream from it passing through a little loch occupying about half that
distance. The burn flowing from Loch Hunder to Loch Eport is only 40
or 50 yards in length. When surveyed on June 2, 1904, the loch was
22'55 feet above sea-level. There was a range of temperature of 7" from
surface to bottom, distributed as shown in the table appended : —

Surface 59°-OFahr.

10 feet 58°-6 „

20 „ ... 57°'3 „

25 „ 53°-6 „

50 , 52°-0

202

BATHYMETRICAL SUKVEY OF

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THE FRESH- WATER LOCHS OF SCOTLAND.

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204 BATHYMETRICAL SURVEY OP

From the table on pages 202 and 203 it will be seen that in the
thirty-nine lochs under consideration 3751 soundings were taken, and that
the aggregate area of the water-surface is 8| square miles, so that the
average number of soundings per square mile of surface is 433. The
aggregate volume of water contained in the lochs is estimated at 3026
millions of cubic feet. The area drained by these lochs is about 45 J
square miles, or about five times the area of the lochs.

THE FRESH-WATEK LOCHS OF SCOTLAND. 205

THE LOCHS OF LEWIS.

THE island of Lewis and Harris is the largest of the lesser British
islands (see Index Map, Fig. 23), only Skye and the Mainland of Shetland
nearly approaching it in size. It measures some 60 miles in length by
30 miles in breadth. Its southern half is mountainous, many peaks
exceeding 2000 feet in height, and a few exceeding 2500 feet. The
northern half is lower.

There are many hundreds of lochs distributed over every part of the
island. In the northern half they are specially numerous, and in the
central part they form a sort of watery maze like that of North Uist.
There are only a few of the narrow, straight, valley lochs, so familiar
on the mainland of Scotland, and those are in the southern mountainous
part of the island ; the majority are small, roundish, or relatively broad,
and the larger ones of extremely irregular form. It was only possible
to survey a small proportion of the numerous lochs, thirty altogether
being sounded.

Five of the lochs exceed 2 miles in length. Loch Langavat is by far
the longest, exceeding 7 miles, and in superficial area is about four times
as great as any other loch. It is, however, exceeded in volume by Loch
Stiainaval, which contains 2843 millions of cubic feet. Loch Suainaval
is also by far the deepest loch, exceeding 200 feet in maximum depth,
while no other loch exceeds 100 feet. Five lochs, Langavat, Scaslavat,
Grunavat, Benisval, and Raonasgail, approach 100 feet in depth. The
mean depth of Loch Suainaval is 108 feet, no other loch exceeding 35
feet. Combining the areas of all the lochs, the extent of fresh water sur-
veyed amounts to nearly 10 square miles, the volume of water to 7400
millions of cubic feet.

The thirty lochs of Lewis surveyed are contained in seventeen distinct
basins, draining independently into the sea. Twelve of these basins
contain only one loch which was surveyed ; three contain two lochs ; the
Thamanabhaidh basin contains four lochs ; the most extensive basin sur-
veyed is the Laxey basin, with its eight lochs. Many extensive basins
were not visited at all.

There follows a table of the seventeen basins and the lochs contained
in them : —

206

BATHYMETRICAL SURVEY OF

Basins.

1 Seaforth

2 Amhuinn Mhor

3 Laxey

4 Creed

5 Bayhead

6 Barvas

7 Ereray

8 Bragor

9 Shawbost

10 Langavat

1 1 Gisla

12 Amhuinn a' Chla-

chain Moire

13 Forsa

14 Caslavat

15 Scaslavat

16 Thamanabhaidh

17 Bodavat

Lochs.
Skebacleit.
Strand avat.
Valtos, nam Faoileag, Trealaval, Fadagoa,

Cuil Airidh a' Flod, Airidh na Ceardaicb, nan

Deaspoirt, Dhombnuill Bbig.
a' Chlacbiin, Vatandip.
Airidb na Lie.
More Barvas.
Urrabag, Bruadale.
an Duna.
Kaoinavat.
Langavat.
Grunavat.
Morsgail.

Stacsavat, Suainaval.

Raonasgail.

Scaslavat.

Dibadale, na Craobhaig, Cro Criosdaig, Benisval.

Bodavat.

Loch Skebacleit (see Plate LXXVIII.) is a very narrow loch, in shape
like the letter T> in the district of Pairc, and a short distance east of the
head of Loch Seaforth. The surrounding land is low, except on the south,
where the hill rises to over 1000 feet. The body of the inverted ± runs
north and south, the cross-stroke east and west. The length, measured in
a straight line, is nearly 1J miles. The portion of the lake running east
and west is 1^ miles long by one-fifth of a mile broad in the centre; the
portion running north and south is 1 mile long and a quarter of a mile
broad near the north end. The southern portion forms a simple basin
with sides sloping gently to a depth of 26 feet opposite the northern
branch. Where this branch goes off is a marked constriction, with a depth
of only 3 feet. For half a mile northwards the bottom is uneven, and the
greatest depth 15 feet. The expanded north end is a small basin of greater
depth, deepest along the west side, where the maximum of 43 feet is found
in a narrow arm running to the north-west. The area is about 194 acres,
the mean depth 15 feet, and the volume 128 millions of cubic feet. The
area draining into the loch measures 7 square miles. Glen Ouirn river
enters the east end of the loch. The Seaforth river issues from the west
end, and, after a winding course of half a mile, enters the head of Loch
Seaforth. The level on the date of the survey (August 12, 1903) was
35'05 feet above sea-level.

The temperature at the surface was 59°'0 Fahr., at 25 feet 59°'0, and
at 40 feet 58'9°.

THE FRESH-WATER LOCHS OF SCOTLAND.

207

Locli Strandarat (see Plate LXXIX.) is a narrow loch, of zigzag out-
line, 1 mile to the west of the head of Loch Erisort, and 1 mile north

Bartholomvir trfm-

FIG, 23. — INDEX MAP OP THE ISLAND OF LEWIS.

of Loch Seaforth. It lies among low moorland, a slightly higher ridge on
the west separating it from Loch Langavat. The length, measured in

208 BATHYMETRICAL SURVEY OP

a straight line from north to south, is lj miles, and the greatest breadth
scarcely half a mile. The loch is shallow throughout, slightly deeper
near the two expanded ends, in the southern of which is a depth of 20 feet,
and in the northern the maximum of 25 feet. The mean depth is nearly
9 feet, the area about 131 acres, and the volume 49 millions of cubic feet.
The drainage area is nearly 4 square miles in extent. Several large burns
come down from the ridge to the west. The discharge is by the Amhuinn
Mhor, a mile long, eastward into the head of Loch Erisort. On the date
of the survey (August 5, 1903) the surface was 47*9 feet above sea-level.

The temperature varied 2° from surface to bottom : surface, 580<0 Fahr. ;
15 feet, 56°-4; and 23 feet, 56°'0.

Loch Valtos (see Plate LXXX.) is a small loch to the west of Laxey,
on the north side of Loch Erisort. The surrounding land is low. In form
it is narrow, with the axis curved and running south-west to north-east,
while a narrow arm runs south-east from the middle of the loch. The
length is two-thirds of a mile, and the greatest breadth, measured into the
south-eastern branch, over a quarter of a mile. There is a constriction
one-fifth of a mile from the west end of the loch, in which is the maximum
depth, 27 feet. East of the constriction it is shallow, the greatest depth
being 13 feet — the little round western basin is slightly deeper, 21 feet close
to the north shore. The mean depth is over 7 feet, the area about 51 acres,
and the volume 16 millions of cubic feet. The drainage area, which
is that of the whole Laxey basin, is 22 square miles. The river Laxey
just touches the northern extremity of the loch, and there are no other
feeders of any size. On the date of the survey (August 15, 1903) the
surface was 24'05 feet above sea-level.

The temperature at the surface was 59°-2 Fahr., at 15 feet 58°-0, and
at 27 feet 57°-6.

LocJi nam Faoileag (see Plate LXXX.) is a small but relatively broad
loch immediately to the east of Loch Trealaval. It lies amid low moor-
land, at the same level as Loch Trealaval, and is commonly regarded as a
portion of that loch. In form it is oblong, with very undulating shores,
and measures two-thirds of a mile from east to west by one-third of a mile
broad. The loch is shallow, in the central part almost flat and about
10 feet deep, the two small depressions of greater depth, 21 and 22 feet
respectively, being close to the shore and at opposite ends of the loch.
The mean depth is about 9 feet, the area about 100 acres, and the volume
38 millions of cubic feet. The drainage area of 17 square miles includes
Loch Trealaval, Loch Fadagoa, and numerous smaller lochs. There is
scarcely any inflow except through Loch Trealaval. The large river
Laxey flows out from the north-east corned.

Loch Trealaval (see Plate LXXX.) is a large loch of very irregular
form, lying about 2 miles north of Balallan on Loch Erisort, The sui>

THE FRESH-WATER LOCHS OF SCOTLAND. 209

rounding moor is low, with slight hills on the west and south-west. It is
a maze of ramifying channels, promontories, and islands, similar to Loch
Scadavay in North Uist, but much less extensive. After Loch Langavat it is
the longest loch in the island, measuring nearly 3 miles, with a maximum
breadth of half a mile. On the whole it is very shallow, having the low
mean depth of 0 feet. There are many little depressions, separated by
shallows, and many large and small islands and boulders further increase
the irregularity of the contours. The two westernmost expansions of the
loch have depths of 26 and 28 feet respectively. The maximum depth of
35 feet is close to the west shore, north-west from Eilean nan Uan. The
superficial area, about 388 acres, is exceeded by only two lochs, Langavat
and Suainaval ; the volume, 156 millions of cubic feet, is equal to that of
Loch Fadagoa, and is exceeded by four lochs, Langavat, Suainaval, Grunavat,
and Benisval. The drainage area, which includes Loch Fadagoa and the
two smaller lochs Airidh, amounts to 16 J square miles. The river Lag na
Linne, which enters at the northern extremity of the loch, conveys the over-
flow of many lochs on the southern slope of the hills Beinn nan Surrag
and Eitshal. A considerable, though very short, stream also enters from
Loch Fadagoa, at the western extremity. The communication with Loch
Faoileag is by a channel nearly 100 yards wide and only 1 foot deep.
Loch Faoileag, from which the river Laxey issues, though here treated as
a separate loch, might be regarded as a part of Loch Trealaval. On the
date when surveyed (August 8, 1903) the surface was 88*5 feet above sea-
level. The temperature at the surface was 57 '3 Fahr., and at 25
feet 57-4.

Loch Fadagoa (see Plate LXXX.) is a fairly large narrow loch
between Lochs Trealaval and Langavat. The surroundings are low moor-
land, except on the south, whe.re there is a hill of moderate elevation.
The outline is extremely irregular, with many constrictions and expansions,
and there are many small islands. The length, from north to south, is a
little over 2 miles ; the breadth, measured into the narrow prolongation
which runs eastward towards Loch Trealaval, is nearly a mile. In corre-
spondence with the irregular outline the bottom is very uneven, and there
are five separate depressions over 20 feet in depth. The largest of
these is in the southern triangular portion of the loch, and includes the
maximum depth of 46 feet. A small hollow in the centre of the loch has
a depth of 3l> feet, and the northernmost depression a depth of 36 feet.
The eastern extension is shallow, the greatest depth being 8 feet. The
mean depth is over 11 feet, the area nearly half a square mile, and the
volume 156 millions of cubic feet, exactly the same as that of Loch
Trealaval. The drainage area exceeds 3 square miles. It includes many
small lochs, the most important being a chain of three, leading westward
to Loch nan Eilean. The outflow is by a stream only about 200 yards
long, with a fall of 6 feet to Loch Trealaval. On the date of the survey

p

210 BATHYMETRICAL SURVEY OF

(August 11, 1903) the surface was 9542 feet above sea-level. The tempera-
ture was uniform at 58°'0»Fahr., identical readings being recorded at the
surface, 20 feet, and 40 feet.

Loch Cuil Airidh a' Flod (see Plate LXXX.) is a small narrow loch of
irregular form, being really an inlet from Loch Trealaval on its south
side. It is nearly a mile in length, and a quarter of a mile in maximum
breadth. It is shallow, with a maximum depth of 9 feet and a mean depth
of 4J feet. The superficial area is about 61 acres, and the volume of
water 12 millions of cubic feet. The drainage area, including Loch
Airidh na Ceardaich, is scarcely 1 square mile. At the north end it joins
Loch Trealaval by a broad channel, and is connected with Loch Airidh na
Ceardaich, which is very slightly higher in level, at the south end.

Loch Airidh na Ceardaich (see Plate LXXX.) is a small loch to the
south of Loch Trealaval, with which it communicates through Loch Cuil
Airidh a' Flod. It is of very irregular shape. The length is scarcely
two-thirds of a mile, and the greatest breadth a quarter of a mile. The
maximum depth is 22 feet, and the mean depth 6 feet. The area is about
36 acres, and the volume 9 millions of cubic feet. The area drained
measures one-fifth of a square mile. When surveyed, the surface was only
an inch higher than Loch Cuil Airidh a' Flod, with which it is connected
at the south-western extremity.

Loch nan Deaspoirt (see Plate LXXX.) is a small triangular loch
between Balallan and Laxey, on the north shore of Loch Erisort. To
north and south many little hills rise from 100 to 200 feet above the
loch. The length from north-west to south-east is three-quarters of a
mile, and the greatest breadth, at the extreme south end, a quarter of
a mile. It is a simple basin, increasing in depth from north-west
to south-east, to the maximum of 56 feet, a quarter of a mile from the
lower end. The depth continues over 40 feet to close to the south end.
The mean depth is 21 feet, the area about 55 acres, and the volume 50
millions of cubic feet. The drainage area, including Loch Dhomhnuill
Bhig, is a little over a square mile. A small burn, a quarter of a mile
long, comes from Loch Dhomhnuill Bhig, and a similar burn goes east
to the head of Loch Valtos. The level was 59-2 feet on August 14, 1 903.
The temperature at the surface was 58°'0 Fahr., at 25 feet 58°-0, and at
48 feet 57°-0.

Loch Dhomhnuill Bhig (see Plate LXXX.) is a small narrowly tri-
angular loch, about 1 mile to the north of Loch Erisort. The low hills
bordering the loch rise to between 200 and 250 feet, or over 150 feet above
the surface. The length from north-west to south-east is a little over half
a mile, the maximum breadth, at the south end, a quarter of a mile. The
loch is shallow, being 4 feet in the middle, and deepening to 8 feet near

THE FRESH- WATER LOCHS OF SCOTLAND. 211

the lower end, and 9 feet near the upper end. The mean depth is nearly
4 feet, the area 43 acres, and the volume, 7 millions of cubic feet, shows
it to be the smallest loch surveyed in Lewis. A small burn flows east
to Loch nan Deaspoirt. The height above sea-level was 82*9 feet on
August 14, 1903.

Loch a' CUachain (see Plate LXXXI.) is a narrow loch about 4 miles
west of Stornoway, the land surface on which it lies rising gradually to
the west. In form it is narrow and oblong, measuring fully half a mile in
length from east to west, and one-fifth of a mile in breadth. It is shallow
and nearly flat-bottomed, with only a very small area near the east end
over 10 feet deep, and the maximum 11 feet. The mean depth is 5J feet,
the area 45 acres, and the volume 1 1 millions of cubic feet. The drainage
area is extensive, including the whole upper waters of the Creed and
several lochs, and measures 12 square miles. The loch is an expansion of
the Creed, which flow in at the west end, and out at the east. The
surface was 211*6 feet above sea-level on July 10, 1903. The temperature
at the surface was 56°*9 Fahr., and at 10 feet 56°*8.

Locli Vatandip (see Plate LXXXI.) is a small narrow loch 4 miles
west of Stornoway. The hills to north and south rise about 100 feet above
the loch. The length from east to west is exactly a mile, and the greatest
breadth one-fifth of a mile. It is a simple, shallow, and even basin, the
10-feet contour closely following the shore, the bottom nearly flat, and
the maximum depth of 17 feet near the east end. Very narrow for
two-thirds of its length, it expands, one-third of a mile from the west end,
into a triangular portion. The mean depth is 10 feet, the area about 64
acres, and the volume 27 millions of cubic feet. The drainage area is less
than half a square mile. From the west end a small burn flows west into
the river Creed. When surveyed on July 11, 1903, the surface was 275*9
feet above sea-level.

Loch Airidh na Lie (see Plate LXXXII.) is a small narrow loch, 1J
miles west of Stornoway. Low hills lie to north and south : on the south
some 100 feet, on the north 15<> feet, above the level of the water. It
measures three-quarters of a mile from east to west, and one-sixth of a
mile in greatest breadth, near the lower end. The bottom is regular and
even, the sides sloping gently to the middle, and the depth gradually
increasing from west to east, with the maximum of 19 feet near the
outflow. The mean depth is 9 feet, the area about 47 acres, and the
volume 19 millions of cubic feet. The area draining into the loch is
nearly 3 square miles, a considerable stream, the Amhuinn a* Ghlinn
Mhoir, flowing in at the west end. The Bayhead river flows out eastward
through the town of Stornoway. The level of the loch on the date of the
survey, July 9, 1903, was 178-7 feet. The surface temperature was 55°*8
Fahr., at 15 feet 55°'7.

212 BATHYMETKICAL SURVEY OF

Loch More Barms (see Plate LXXXII.) is a broad sheet of water,
lying close to the sea-shore, near Barvas on the west coast, in a broad
stretch of low country. It is a mile long from west to east, and half a
mile broad. It is flat-bottomed, and very shallow, with a maximum depth
of 8 feet, and a mean depth of 4^- feet. The superficial area is about 239
acres, and the volume of water 45 millions of cubic feet. It drains an
area of 33 square miles, chiefly by Glen Barvas. It is separated from the
sea by a mere sandbar, and when surveyed on August 22, 1903, was only
9*7 feet above sea-level. The surface temperature was 53°*1 Fahr.

Loch Urrdhag (see Plate LXXXIII.) is a loch of moderate size,
between Barvas and Bragor, a little more than a mile from the shore.
The surrounding land nowhere rises far above the loch. It is roughly
hammer-shaped, with a narrow stem running north and south, and an
expanded northern portion. It is l\ miles long, and fully half a mile
broad near the north end. It is a simple basin, shallow in the south, and
gradually deepening northward to the maximum of 33 feet in the centre
of the expanded portion. The mean depth is 11^ feet, the area about 211
acres, and the volume 105 millions of cubic feet. The drainage from 7J
square miles of country enters the loch chiefly from Glen Bruadale,
through Loch Bruadale, which is only cut off from Loch Urrahag by a
causeway. The outflow is by Glen Ereray, past several mills, into Loch
Ereray.

The surface was 89-3 feet above sea-level on August 20, 1903. The
temperature was 55°'4 Fahr. throughout.

Loch Bruadale (see Plate LXXXIII.) is a small loch close to the south
of Loch Urrahag, amid low country. It is half a mile long, one-third of a
mile broad, flat-bottomed, and shallow — only 6 feet deep over the greater
part of the area. The mean depth is 4^ feet, the area about 66 acres, and
and the volume 13 millions of cubic feet. It receives the drainage of
6 square miles of country, including the large Loch Breivat, chiefly
brought by the Glen Bruadale river.

It is scarcely separated from Loch Urrahag, and the level was only
3 inches higher, or 89'5 feet above sea-level, on August 20, 1903.

Loch an Duna (see Plate LXXXIV.) is a small broad loch in Bragor,
about a mile from the coast. It is roughly rhomboid in shape, with a
narrow arm running westward. It is half a mile long, by one-third of a
mile broad. The basin is simple and deepens towards the east, where the
maximum of 29 feet is found near the east shore. The mean depth is
13 feet, the area about 71 acres, and the volume 41 millions of cubic feet.
The area drained is very limited, less than a square mile. The outflow is
by the Allt na Muilne, flowing north past several mills into Loch Orclais.
The surface was 97-6 feet above sea-level on August 22, 1903.

THE FRESH- WATER LOCHS OF SCOTLAND. 213

Loch Eaoinamt (see Plate LXXXIV.) is a small loch about 3 miles
north-east of Carloway, on the west coast, on a land surface gently rising
towards the south. It is three-quarters of a mile long, from east to west,
and a quarter of a mile broad at the extreme west end. It is narrow at
the east end, and expands and deepens westward. A very small area,
exceeding 50 feet in depth, with the maximum of 01 feet, lies close to the
north shore and near the west end ; the mean depth is 20^ feet, the area
about 73 acres, and the volume 65 millions of cubic feet. The drainage
area is barely half a square mile. The outflow is by a small stream, which,
leaving the east end of the loch, flows north past several mills, into Loch
na Muilne. The surface was 109*5 feet above sea-level on August 22,
1903. The temperature only varied one-fifth of a degree from surface to
bottom— surface, 55°-8 Fahr. ; 54 feet, 55°'6.

Loch Langavat (see Plate LXXXV.). — Loch Langavat, the most
extensive body of fresh water in the island of Lewis, is centrally situated
in the broadest part of the island, between Lochs Seaforth and Erisort on
the east, and Lochs Resort and Little Roag on the west. The upper end
of the loch lies among hills of over 1500 feet in height. The land falls
towards the lower end, which borders on a broad plain, studded with
innumerable lochs, stretching for miles to the north and east. In form it
is very irregular — long and narrow, with undulating shore-line and zigzag
axis — several constrictions and bends dividing it into distinct basins. The
length, in a straight line from south-west to north-east, is 7 J miles ; if the
centre line were followed it would be much greater. The maximum
breadth is three-quarters of a mile. There are three large basins of over
25 feet in depth, besides some smaller depressions. The largest and
deepest basin occupies the southern section of the loch, which is 3^ miles
long, fully half a mile broad in the centre, and is almost straight. The
25-feet contour is parallel with the shore-line, and encloses an area nearly
3 miles long. The area enclosed by the 50-feet contour is fully a mile in
length, and contains two small areas over 75 feet in depth, with maxima
of 97 and 98 feet respectively, separated by an elevation on which the
depth is 72 feet. This large basin is separated from the next by a very
narrow strait where the depth is only 9 feet. The mid basin is deepest
at the south-western end, where the depth of 90 feet occurs, and shallows
and contracts towards the north-east. The next bend to the east leads to
the third section of the loch, which is as long and broad as the first
(85 miles long and three-quarters of a mile broad), but of much more com-
plex form, the axis curving, the shore-line much broken up, the contours
irregular and interrupted by numerous islands. The largest area of over
25 feet is at the south-west end, and has a maximum depth of 40 feet ;
smaller areas of greater depth are found further to the north-east. In the
last large expansion near the lower end of the loch is a depth of 65 feet.
The mean depth is 25 feet, the superficial area 3J square miles, and the

214 BATHYMETRICAL SUKVEY OF

volume of water 2388 millions of cubic feet. It is the only loch in Lewis
the area of which exceeds a square mile. Though four times the area of Loch
Suainaval, the next to it in size, the volume is less by 450 millions of cubic
feet. The drainage area measures nearly 28 square miles. The feeders
are all small local streams, the largest, Glen Langadale, at the upper end
of the loch. From near the northern extremity of the loch two wide
channels lead into Loch Airidh na h'Airde, whence a chain of lochs, with
only very short connecting streams, extends some 4 miles northward to the
head of Loch Koag near Callernish. Loch Coirigerod, 1J miles long,
which stands at a higher level than Loch Langavat, was not surveyed.

The surface at the time of the survey (July 13 to 18, 1903) was
108-0 feet above sea-level.

Temperature Observations. — The following^ serials were taken during
the survey : —

July 16. July 17.

Surface 56°-8 56°-l

20 feet 56°-2 56°-l

50 „ 55°-4 56°-0

87 „ 55°-l

92 „ 55°-0

Loch Grunavat (see Plate LXXXVI.) is a fairly large loch, lying about
2 miles to the west of Little Loch Roag. Though of the narrow form of
valley lochs, it does not occupy a well-marked valley. High land 'occurs at
the ends of the loch, while the sides are comparatively low. The length
is 21 miles, and the greatest breadth, about the middle of the loch> half a
mile. The shore-line is irregular, with several promontories and deep
inlets. A large island occupies almost the exact centre of the loch, South
of the island the loch is almost everywhere shallow ; north of it is a simple
and comparatively deep basin. The 25-feet and 50-feet contours extend a
short distance south of the island, the deep channel passing between the
island and the west shore. Halfway between the island and the north end
is a small area over 75 feet in depth, with the maximum of 90 feet. The
mean depth is 28 feet, the area about 387 acres, and the volume of water 478
millions of cubic feet. The area draining into the loch is 3 square miles ;
there are no inflowing streams of any size. The outflow, near the southern
end of the loch, through the inlet called Loch na Ciste, which could not be
entered, is by the Gisla river, flowing 2 miles eastward into Little Loch
Roag. The surface was 365-4 feet above sea-level on July 28, 1903.

The temperature had a range of 6° Fahr. from surface to bottom, the
readings being : —

Surface 61°'5 Fahr.

15 feet 59°-2 „

25 „ 58°-0 „

50 „ 56°-l „

80 , 55°-6

THE FRESH-WATER LOCHS OF SCOTLAND. '215

Morsyail (see Plate LXXXVII.) is a small broad loch near the
head of Little Loch Roag. The neighbouring hills are somewhat distant,
the immediate surroundings low, except southward, where Scalaval Mula
rises to 850 feet. The outline is roughly rhomboid, the length a little
more than half a mile from south to north, the greatest breadth one-third
of a mile. The basin is simple, of moderate depth, a narrow strip of over
25 feet in depth lying west of the centre, with a maximum depth of
31 feet. The mean depth is 12 feet, the area about 65 acres, and the
volume of water 35 millions of cubic feet. The drainage area is extensive,
extending to 10 square miles. The principal stream entering the loch is
the Amhuinn a' Loin, conveying the drainage of the south side of Beinn
Mheadhonach. The Amhuinn a' Chlachain Mhoire flows out northwards.
The height of the surface above sea-level could not be measured, but is
estimated at about 70 feet.

The temperature at the surface on August 3, 1903, was 60°-1 Fahr., at
15 feet 59°-l, and at 29 feet 58°-9.

Loch Stacsavat (see Plate LXXXVI.) is a small triangular loch
intervening between Loch Suainaval and the sea at Uig. The hills on the
west rise only about luu feet above the loch ; on the east they are higher,
and rise steeply from the shore to 450 feet. It is three-quarters of a mile
long by one-third of a mile in greatest breadth. It is a simple basin, with
the 25-feet contour roughly parallel to the shore, and the maximum depth
of 40 feet about the centre. The mean depth is 17J feet, the area about
87 acres, and the volume 66 millions of cubic feet. The area drained,
including Loch Suainaval, is nearly 11 square miles. On the south the
river Eyscleit enters from Loch Suainaval ; the river Forsa, a quarter of a
mile long, passes northward by a series of small waterfalls into Lon Erista,
the head of Camus Uig. The surface on the date of the survey, July 25,
1903, was 35-9 feet above sea-level.

The temperature varied more than 5° Fahr. from surface to bottom,
thus:—

Surface 61c-8 Fahr.

10 feet 61-4 „

20 „ 59--0 „

30 „ 57°'0 „

37 „ S6--4 „

Considering the water-supply derived from Loch Suainaval, it is
remarkable that the whole series should be so much higher than that taken
in Loch Suainaval on the previous day.

Loch Suainnc'tl (see Plate LXXXVI.), called locally Suainavat, is a
large and somewhat broad loch, situated a mile or two south-east of Uig.
It occupies a narrow steep-sided valley, the hills bounding which are
highest on the west , while a comparatively low ridge separates it on the

216 BATHYMETR1CAL SURVEY OF

east from Loch Grunavat. An isolated hill, Suainaval, 1403 feet in height,
stands at the lower end of the loch on the east side. It is one of the
longest lochs in Lewis, measuring 2f miles in a straight line from north to
south. The greatest breadth towards the north end is a little more than
half a mile.

Loch Suainaval is a simple basin, with the slope of the bottom steepest
from the shore to the depth of 100 feet. The 100-feet contour closely
follows the shore-line except at the ends, and the area enclosed by it is 2^
miles in length. From the 100-feet contour to the centre the slope is more
gradual, and only two small areas exceed 200 feet in depth. The larger of
these areas, in the broadest part of the loch, is one-third of a mile long by
one-fifth of a mile broad, and is flat-bottomed, with a greatest depth of
212 feet. The lesser 200-feet area is a little south of the centre, is very
narrow, and includes the maximum depth of 219 feet. A study of the
contours shows that the loch has the U~snaPe^ cross-section characteristic
of lochs formed in valleys which have been occupied by glaciers.1' The
mean depth, 108J feet, is very great, more than three times that of any
other loch in Lewis.

The superficial area is nearly a square mile, or about one-fourth that
of Loch Langavat. The volume of water, 2843 millions of cubic feet,
shows that Loch Suainaval is the greatest lake in Lewis, being 450
millions of cubic feet more than that of Loch Langavat, six times that of
Loch Grunavat, and eighteen times that of Loch Trealaval or Loch
Fadagoa. The drainage area amounts to nearly 10 square miles. The
outflow northward to Loch Stacsavat is by the short river Eyscleit, with
a fall of about 1^ feet. The surface was 37*4 feet above sea-level on
July 24, 1903, which is about a foot lower than the level found by the
Ordnance Survey on October 2, 1895.

A series of temperatures taken on July 24, 1903, showed, consistently
with the great depth of the loch, a greater range than was observed in any
other loch in Lewis. The range from surface to bottom was 11°'2 Fahr.,
and the distribution as shown in the following table : —

Surface.... 57° '0 Fahr.

25 feet 55°-2

50 „ 53°-0

75 „ 50°-4

100 „ 47°-7

200 „ 45°-8

Loch Raonasyail (see Plate LXXXVIII.) is a small loch among the
high hills which lie between the south end of Loch Suainaval and the west
coast. It occupies a narrow valley between Tahaval, 1688 feet, on the
east, and Mealasval, 1885 feet, on the west, which rise in steep crags
covered with large and small stones on either side. The loch is of oblong

* See Collet and Johnston, " On the Formation of Certain Lakes in the Highands,"
Proc. Boy. Soc. Edin., vol. 26, p. 108 (1906).

THE FRESH- WATER LOCHS OF SCOTLAND. 217

form, two-thirds of a mile long from north to south, and one-fifth of a mile
broad. It is a simple basin, the slope of the bottom steeper on the east
side, so that the narrow area of over 75 feet in depth lies near the east
shore. The maximum depth of 95 feet lies north of the centre. The
mean depth is 32 feet, the area about 66 acres, and the volume 94 millions
of cubic feet. The drainage area measures 2 square miles. The Amhuinn
Ehid enters at the south end, and the Amhuinn Caslavat, issuing from the
north end, flows some 3 miles northward into a branch of Camus Uig
The surface of the loch was 288'0 feet above sea-level on July 29, 1903.
The- temperature had a range of 6° Fahr. from surface to bottom : —

Surface... 59C<0 Fahr.

25 feet 56c-9 „

50 „ 53^-6 „

93 „ 53°-0 „

Loch Scaslacat (see Plate LXXXVIII.) is a small triangular loch close
to the shore of Camis Uig at Carnis, surrounded by low hills, rising 100
to 200 feet above the loch. The length, from south-west to north-east, is
over half a mile, the greatest breadth one -fifth of a mile. The basin is
simple, the bottom sloping gently, except on the north-east side which is
very steep, to the maximum depth of 82 feet, close to the north-east shore.
The mean depth is 34^ feet, the area about 48 acres, and the volume 73
millions of cubic feet. The drainage area is less than half a square mile.
The outflow is by an insignificant stream, which flows for a quarter of a
mile northward into a branch of Camus Uig. The surface was 122'9 feet
above sea-level on July 29, 1903.

Loch Dibadale (see Plate LXXXVII.) is a small narrow loch lying
between Loch Suainaval and Loch Resort. It is situated in a corrie
between the two hills, Mula Chaolartan and Tamanaisval (1530 feet). It
measures two-thirds of a mile from north-west to south-east, and one-sixth
of a mile in greatest breadth. It is a simple basin and relatively deep,
deepest in the southern half, with the maximum, 61 feet, somewhat south
of the centre. The mean depth is 28 feet, the area about 42 acres, and the
volume 51 millions of cubic feet The drainage area is 1^ square miles in
extent. The Amhuinn Ghlascleit flows out from the south end and joins
the Amhuinn Thamanabhaidh. Loch Dibadale lies at. a considerable
elevation, 416'8 feet above sea-level on July 31, 1903.

Temperatures in the deepest part gave : —

Surface 56°-5 Fahr.

25 feet ... 56°-3 „

55 „ 53^O „

Loch na Craobhaiy (see Plate L XXXIX.) is a loch of moderate size,
forming the lowest of the chain of lochs draining into Loch Thamanabhaidh,
to the north of Loch Resort. The hills bounding the valley in which it

218 BATHYMETKICAL SURVEY OF

lies are much higher on the north side. On the flat southward towards
Loch Bodavat are numerous small lochans. The length from west to east is
a mile, the greatest breadth, at the west end, nearly half a mile. The main
part of the loch is a simple basin, with the maximum depth, 50 feet, near
the west shore. A narrow shallow arm, 13 feet deep at the mouth (greatest
depth within 8 feet), runs one-third of a mile eastward and receives the
burn from Loch Cro Criosdaig. The mean depth is nearly 1 7 feet, the area
about 128 acres, and the volume 93 millions of cubic feet. It drains
an area of 6 square miles, including Lochs Cro Criosdaig and Benisval, from
which its water is chiefly derived. It discharges by Amhuinn Thainana-
bhaidh westward into the sea-loch of the same name. The surface was 1 99-4
feet above sea-level on August 4, 1903. The temperature varied nearly
4° Fahr. from surface to bottom : —

Surface 59°-0 Fahr.

25 feet 59°-0

35 „ 58°-6

40 „ 58°-0

45 „ 57°-2

49 „ 55°-2

Loch Cro Criosdaig (see Plate LXXXIX.) is a small loch on the stream
connecting Loch Benisval with Loch na Craobhaig, to the north of Loch
Resort. To the south the hills rise 100 feet above the surface, towards
Loch Benisval, northward they rise more gradually to Beinn Mheadhonach,
1303 feet. In form it is irregular, measuring four-fifths of a mile from
west to east, with a maximum breadth of one- third of a mile. It is a
shallow basin, nearly two-thirds of the area being covered by less than 10
feet of water, and deeper towards the east, where there are two little holes
20 and 21 feet in depth. The mean depth is 9 feet, the area about 80
acres, and the volume 31 millions of cubic feet. It drains an area of 3
square miles, including Loch Benisval, and overflows by the Amhuinn
Uidh Phail, 300 yards long, westward to Loch na Craobhaig. The
surface was 229*8 feet above sea-level on August 1, 1903.

Loch Benisval (see Plate LXXXIX.) is a broad sheet of water about
half a mile north of Loch Resort, near the head of that loch. Low hills
surround the loch, rising from 50 to 300 feet above the surface, the highest
being Benisval, to the south-east, 624 feet in height, or 350 feet above the
loch. The main loclTis of oblong form, with a narrow prolongation to the
south-east. It is three-quarters of a mile long, measured in a straight line
from north to south, and half a mile broad. It is a simple and relatively
deep basin, with sides most steeply sloping along the base of Benisval, and
the maximum depth, 95 feet, near the east shore. The northern end, where
are many small islands, is shallow. Only two lochs, Langavat and
Suainaval, are deeper, and Loch Raonasgail is of the same depth. The mean
depth of nearly 35 feet is exceeded only by Loch Suainaval and equalled

THE FRESH- WATER LOCHS OF SCOTLAND. 219

by Loch Scaslavat. The area 'is about 172 acres, and the volume 260
millions of cubic feet. It receives only local drainage from an area of
scarcely 1 mile square, and discharges northward by the Amhuinn
Benisval, a quarter of a mile long, into Loch Cro Criosdaig. The height
above sea-level was 278'0 feet on August 3, 1903.

A series of temperatures showed a range of 3J° Fahr. from surface to
bottom : —

Surface 58°'2 Fahr.

25 feet 58°-0 „

50 „ 55°-2 „

90 „ ... 54°-8 „

Loch Bodavat (see Plate LXXXIX.) is a small loch to the north of
Loch Resort, into which it drains by a stream about a mile long. The
hills to the north-west rise some 300 feet, those on the south-east 200
feet, above the loch. In form it is narrow, with a sigmoid curvature, and
measures nearly a mile from north-east to south-west in a straight line
between the ends. The greatest breadth near the centre is a quarter of a
mile. The basin is simple, deepest in the middle, with the maximum of
46 feet a little east of the centre. The mean depth is 13 feet, the area
about 91 acres, and the volume 50 millions of cubic feet. It receives the
drainage of an area of 1^ square miles. The outflow is from the south-west
corner of the loch. The surface was 179'6 feet above sea-level on August
1, 1903.

The range of temperature from surface to bottom was 5° Fahr. : —

Surface 60°-0 Fahr.

20 feet 59°-0 „

30 „ 58°-6 „

35 „ 55°-7 „

40 „ 55°-0 „

From the following table it will be seen that in the thirty lochs under
consideration 2896 soundings were taken, and that the aggregate area
of the water-surface is 9| square miles, so that the average number of
soundings per square mile of surface is 300. The aggregate volume of
water contained in the lochs is estimated at 7409 millions of cubic feet.
The area drained by these lochs is 152 square miles, or nearly sixteen
times the area of the lochs.

220

BATHYMETRICAL SURVEY OF

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THE FRESH-WATER LOCHS OF SCOTLAND.

221

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222 BATHYMETRICAL SUKVET OF

THE LOCHS OF OEKNEY.

THE Mainland of Orkney possesses many fine lochs. The land surface
consists of a series of low dark- topped hills, none reaching 1000 feet in
height, between which are broad stretches of level or gently undulating
moorland, now in great part under cultivation. In correspondence with
this conformation of the land, and the absence of narrow valleys, the lochs
occupying the hollows are all relatively broad, and they are without excep-
tion shallow and flat-bottomed. The two very large bodies of water, the
Lochs of Stenness and Harray, which ramify into the very heart of the
island, are subject to the influence of the tides, though their level is but
slightly affected.

In the mountainous islands of Hoy and Rousay there are narrow valley
lochs of greater depth than any on the Mainland. On the other islands of
the group, which are quite low, there are only a few unimportant lochs,
which were not surveyed. In the three islands visited (see Index Map, Fig.
24) fourteen lochs were surveyed. The largest, in every respect, is the Loch
of Harray ; the Loch of Stenness is little inferior in size, but all the others are
much smaller. The deepest loch on the Mainland, the Loch of Stenness,
17 feet in depth, is slightly exceeded in depth by the Muckle Water in
Rousay, but by far the deepest loch surveyed is the little Hoglinns Water
in Hoy, which is 57 feet deep. The combined superficial areas of all the
lochs surveyed amounts to 10 square miles, and the area draining into
these lochs exceeds 90 square miles.

The Island of Hoy is the most mountainous of the Orkneys. With the
exception of the Peninsula of South Walls, joined to the main island
merely by a causeway, the island consists of one mountainous mass, rising
from south to north, where it culminates in three peaks of over 1300 feet
in height, separated by deep glens which cut right across the island. The
central peak, the Ward hill, 1564 feet in height/ is the highest point in
Orkney, and even exceeds the highest hill in Shetland (Ronas hill,
1475 feet) by nearly 100 feet. On the southern slope of the island are
several lochs, which, from their highland situation, might be expected to
be deeper than the lochs in the plains of Pomona. That this is in fact the
case can be definitely stated of one little loch, the Hoglinns Water, the
survey of which, begun by the Lake Survey, was completed by Mr. William
Mar wick, who found a depth of 57 feet. The largest loch in Hoy, the
Heldale Water, about a mile in length, was not suryeyed.

THE FEESH-WATER LOCHS OP SCOTLAND.

223

The only extensive basin in the islands is the Harray basin, which
drains 60 square miles of conntry, and includes five lochs which were
surveyed. Lochs Hundland and Boardhouse are in one basin, the Muckle
and Peerie Waters in Rousay are in another ; all the other lochs drain
independently into the sea. The lochs surveyed thus fall into eight distinct

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basins. The shores of all the lochs slope at a very low angle, and are
paved with flat stones, so that approach to the shore in a boat was usually
difficult, except at spots artificially deepened.

Though some of the lochs were partly overgrown with weeds, very
commonly the bottom was free from weeds, and could be seen in the
deepest parts. The paving of flat stones could be seen to continue all

224 BATHYMETRICAL SURVEY OP

over, and despite the great amount of organic debris resulting from the
myriads of animals and plants living in the water, as well as sediment
brought in by the streams, the stones were clean, or there was only a thin
slimy film due to the growth of diatoms and other algae. How is the
clean paved bottom and the absence of peaty deposit so general at the
bottoms of these lochs to be accounted for ? Is all the sediment derived
from every source carried off by the ordinary slow current of the loch, and
is the paved bottom an original and permanent feature ? It does not accord
with experience of shallow lochs elsewhere to suppose this. Such lochs
commonly silt up, and become overgrown with weeds, and are converted
eventually into marshes. If these lochs of Orkney are silting up in the
usual way, why the clean bottom and freedom from deposit ? An explana-
tion may be found in supposing that the lochs are violently agitated to the
very bottom during gales, the stones re-arranged on the top of the latest
formed mud, and the material in suspension in the water carried off during
spates.

Loch of Stenness (see Plate XC.). — The Loch of Stenness is a large
sheet of salt water, measuring nearly 4 miles long and 1 J miles broad, and
is about 2 miles north-east of the town of Stromness. The surrounding
heather-clad moorland abounds in monuments of ancient peoples. In
places the action of the waves has worn the shores into very low cliffs of
rock or gravel, but in general the slope is gentle to the water's edge. The
axis of the loch runs nortli-west to south-east, with a slight sigmoid
curvature. The greatest breadth is in the centre, where a broad bay run-
ning to the south-west branches into arms running to north-west and
south-east. In the southern bay the tide enters from the Bay of Ireland,
under the Bridge of Waith. Though the channel is broad, and the access
free, the level of the loch is but little affected by the tides, which indicates
that the bar is but little below ordinary high-water level. At the eastern
extremity the loch communicates with the Loch of Harray, under the Bridge
of Brogar. During the whole of our stay in the islands the two lochs never
differed measurably in level, though a current could be seen in one direc-
tion or the other. Marine algae grow throughout the loch, and the fauna is
marine.

The Loch of Stenness is flat-bottomed, and has a mean depth of 10^ feet,
and a maximum depth of 17 feet, near the south-eastern extremity. The
superficial area is 2J square miles, and the volume of water 716 millions of
cubic feet. The drainage area, including the Loch of Harray and many
small lochs, measures 60 square miles. Apart from the inflow at the
Bridge of Brogar, only a few small burns enter the loch. The surface at
the date of the survey (August 19, 1903) was 3'6 feet above sea-level.
Sir Walter Scott refers to both lochs (Stenness and Harray) as the Loch
of Stenness.

The surface temperature on August 19, 1903, was 58°'0 Fahr., and on
August 20, 60°-2.

THE FRESH- WATER LOCHS OF SCOTLAND. 225

Loch of Harray (see Plate XC.). — The Loch of Harray, the largest in
the islands, lies immediately to the north of the Loch of Stenness. The axis
runs nearly north and sonth. The southern portion is elongate, with undu-
lating shore-line ; the northern part bifurcates into two broad inlets, giving
the whole loch the approximate form of the letter Y. The surrounding
land is undulating and everywhere low. The east side is principally farm-
land— there are extensive wet meadows (as at Kirk Ness) — moorland,
and here and there low cliffs of gravel or rock. The Bridge of Brogar is
built on the rocky barrier separating the Loch of Harray from the Loch of
Stenness. The length, measured in a straight line, is 4f miles, and the
greatest breadth 1| miles. The mean breadth is three-quarters of a mile.
There are many islands, extensive shoals, and isolated stones. The bottom
is flat, and the mean depth is about 9 feet. The greatest depth, 14 feet,
occurs nearly in the narrowest part of the loch. The superficial area is 3|
square miles, and the volume of water 951 millions of cubic feet.

The area of country draining into the loch is about 45 square miles.
The largest streams are the Burn of Hourston, draining several small
lochs, and entering the Loch of Harray at the north end, and the Burn of
Netherbrough, flowing in at the east side. The outflow at the Bridge of
Brogar is, in certain states of the tide, converted into an inflow. There
was always a current out or in during the survey, but there was never a
measurable difference of level. The surface was 3*6 feet above sea-level
on August 21, 1903. The temperature was 55°'0 Fahr. both at the surface
and at a depth of 14 feet.

Though there is a free ingress of water from the Loch of Stenness, and
the shores of that loch are overgrown by marine algaB close up to the
Bridge of Brogar, the brackish water entering the Loch of Harray appears
to be insufficient to have much effect on its biology. No sea -weeds were
seen on the east side of the Bridge, the water was fresh to the taste, and
the ordinary fresh-water plankton animals were present.

Loch of Bosquoy (see Plate XC.). — A small loch of rhomboid form
near the north-east corner of the Loch of Harray, into which it drains
by a short mill stream controlled by a sluice. It is surrounded by boggy
meadowland. There are many islets of reeds in the western part of the
loch. The length is two-thirds of a mile, and the breadth nearly one-
third of a mile. The greatest depth is 5 feet near the north shore and
east end. There is a considerable flat-bottomed area 4 feet deep. The
mean depth is 2J feet, the area about 65 acres, and the volume 7 millions
of cubic feet. There is a considerable drainage area (3J miles) chiefly on
the Hill of Milldoe (734 feet) on the east, from which the Corrigal burn
flows. Where it enters the loch the stream is known as the Burn of
Layaw. The level was estimated at 36 feet above sea-level.

Loch of Sabiston (see Plate XCI.).— This small loch in the Harray
basin, also known as the Loch of Housby, lies 1J miles north of the

Q

226 BATHYMETRICAL SURVEY OF

Loch of Harray. It is surrounded by a boggy flat, except on the north,
where the Hill of Greenay rises. Rock is seen at several points on the
north-east shore. The length is fully half a mile, and the breadth fully
a quarter of a mile. The bottom is flat, with a maximum depth of 3 feet,
and a large area of this same depth. The north-west corner is filled with
reeds. The mean depth is 1J feet, the area about 77 acres, and the volume
5 millions of cubic feet. The drainage area measures fully 3 square
miles. The outflow is westward by a small stream, utilized as a mill
stream, into the Burn of Warth. The surface was 51-7 feet above sea-
level on September 6, 1906.

Loch of Isbister (see Plate XCL). — A small loch, square or somewhat
cruciform in shape, near the Church of Twatt, and 1J miles south of the
Loch of Boardhouse. It is surrounded by extensive boggy flats, especially
to the west, so that a rise of even a foot in level would greatly extend
the area of the loch. It is extremely shallow, and much obstructed by
stones. The length from north to south is nearly two-thirds of a mile ;
the breadth from east to west is a little less. The greatest depth, 3 feet,
is at the east end. The mean depth is 1J feet, the area about 80 acres,
and the volume 5 millions of cubic feet. The drainage area is 4J square
miles. A drain with sluice leads to the Loch of Banks. The surface
temperature was 64°- 6 Fahr. on September 1, 1906, the highest observed
in Orkney. The bottom is free from weeds, except in the southern corner,
and covered with grey clayey mud. The level was estimated at about

40 feet above sea-level.

Loch of Kirbister (see Plate XCII.).— The Loch of Kirbister (or Loch
of Orphir) is a loch of moderate size, and somewhat triangular shape,
in the parish of Orphir, 5 miles south-west of Kirkwall. It lies amid
cultivated land in a broad valley between hills of over 700 and 800 feet
respectively. It is l£ miles long, and fully half a mile broad. The
bottom is almost perfectly flat, a great central area being uniformly
5 feet deep. The maximum depth is 6 feet, and the mean depth 4 feet.
The area of the surface is about 227 acres, and the volume of water

41 millions of cubic feet. The drainage area measures 8 square miles.
The largest burns are those entering at the two ends of the loch. The
outflow is near the southern end, by a mill burn, about half a mile long,
with a rocky channel, flowing into Waulkmill bay. The surface was
52-1 feet above sea-level on August 14, 1903. The surface temperature
was 57°'0 Fahr.

Loch of Tankerness (see Plate XCII.) is a triangular loch of moderate
size, near St. Andrew's church, 4 miles east of Kirkwall, surrounded
by pasture and wet meadows. It is nearly a mile long by half a mile
broad. It is shallow and flat-bottomed, very gradually deepening from

THE FRESH-WATER LOCHS OF SCOTLAND. 227

west to east, where the maximum depth of 7 feet is found. The mean
depth is 4£ feet, the area about 149 acres, and the volume 28 millions of
cubic feet. The drainage area is. about a square mile. The outflow is
by Mill burn, a quarter of a mile long, issuing from the south-west corner
of the loch. The surface was 13-9 feet above sea-level on August 17,
1903, and the surface temperature was 58°'5 Fahr.

Loch of Swannay (see Plate XCIIL). — The Loch of Swannay (or
Swona, or S wanna) is a large loch of elliptical form, in the extreme north
of Pomona, at Costa head. It is surrounded by moorland, in part
cultivated. The shores are paved with flat stones. Under Costa hill
are ranges of crags. The Muckle Holm island is stony, and there are
many stony shoals, especially south of the island, and along the west
shore. The length is 2 miles, and the greatest breadth two-thirds of
a mile. Around the Muckle Holm the bottom is irregular and shoaly.
South of the island is a considerable flat of 8 feet deep. North of the
island is a large flat-bottomed basin, gradually deepening from 12 feet
to 16 feet near the north end. The mean depth is 9J feet, the area about
603 acres, or nearly one square mile, and the volume 242 millions of
cubic feet. The drainage area is fully 5 square miles. A small burn
enters at the southern end, and the Swannay. burn flows out at the north-
west corner, over a dam with a sluice, which is now disused. There is
rock in the stream at the outflow. The bottom is visible to a depth of
8 or 10 feet, and is stony, with little or no deposit of mud. The surface
was 134'55 feet above sea-level on August 31,' 1906. The temperature
at the surface was 57°-7 Fahr., at 15 feet 57°'0.

Loch of Boardhouse (see Plate XCIII.). — The Loch of Boardhouse,
which, in accordance with the Orcadian custom of naming a loch in-
differently from any conspicuous feature in its neighbourhood, also receives
the appellations Loch of Birsay, Loch of Twatt, Loch of Kirbuster, Barony
Loch, and perhaps yet others, is a large and broad loch in the parish of
Birsay, about half a mile east of the village of that name. It lies amid
fields gently sloping up from the shore, with patches of moorland. Ravie
hill, on the south-west, and Kirbuster hill on the north-east, are heather-
topped hills of no great elevation. The shores are stony, and so shallow
that they are difficult to approach in a boat — the grass slopes come quite
to the water's edge, with hardly any beach. The only rock seen was at
the original outflow. The length is 2 miles, and the greatest breadth
near the eastern end two-thirds of a mile. The bottom is flat, and
gradually deepens from 5 feet at the north-west end to the maximum
depth of 9 feet close to the east end. The mean depth is 6 feet, the area
nearly a square mile, and the volume 150 millions of cubic feet. The
drainage area is 1 3 \ square miles. The Kirbuster burn, a fair-sized river,
enters at the east end. From the north-west corner the Birsay burn flows

228 BATHYMETRICAL SUEVEY OF

somewhat more than half a mile, westward, and enters the sea at the
village of Birsay. On August 30, 1906, the surface was 50-85 feet above
the sea. The temperature was 57°*3 Fahr. throughout.

Loch of Hundland (see Plate XCIII.) is a triangular loch of moderate
size, lying between the larger Lochs Swannay and Boardhouse. The land
is higher on the east, where Hundland hill rises to 150 feet above the
surface. The west side is low moor. The shores are stony, and there
are many stony islands and shoals. The bottom, paved with flat stones,
is visible at depths of 4 to 5 feet. In the deepest part of the loch are
large beds of Potamogeton, reaching the surface from a depth of 7 feet.
The length from north to south is Ij miles, and the greatest breadth
slightly exceeds half a mile. The bottom is flat, and in the great central
portion varies between 5 and 7 feet in depth. The maximum of 7 feet
occurs in a narrow strip near the eastern shore, in "the widest part of the
loch. The mean depth is about 4 feet, the superficial area nearly half
a square mile, and the volume 51 millions of cubic feet. The drainage
area is large, including the Durka dale, a glen about 5 miles long, and
measures 9^ square miles. The Kirbuster burn flows from the south-east
corner to the Loch of Boardhouse through a grassy flat. Rock is seen
in the bed of the stream at the bridge carrying the public road. On
September 1, 1906, the surface was 89'7 feet above sea-level. The
temperature was 62°-0 Fahr. throughout.

Loch of Skaill (see Plate XCIV.) is a small loch on the west coast of
Pomona, half a mile south-east of the Bay of Skaill. It is of triangular
form, and broadest at the west end. It lies amid stony fields, and a boggy
flat intervenes between the loch and the Bay of Skaill. Through this the
outflow goes by a small burn, utilized as a mill stream. Some rock is seen
on the northern shore and close to the outflow. The island in the centre
is artificial, formed of flat stones, and measures about 20 yards across.
The length is nearly one mile, and the maximum breadth half a mile.
The bottom is flat and covered by a yellowish mud. The western bay is
filled with reeds. The maximum depth is 4 feet, the mean depth 2 feet,
the area a quarter of a square mile, and the volume 14 millions of cubic
feet. The loch drains an area of one square mile.

On August 29, 1906, the surface was 26'9 feet above sea-level, and the
temperature was 58°*6 Fahr.

MuckU Water (see Plate XCI.) is a narrow straight loch, lying at
a considerable elevation (322 feet) among the hills, in the island of
Kousay. The shores are rocky on the western side of the loch. The
south shore in the eastern half is a high bank of peat. There is a broad
stony beach. The length is l\ miles, and the breadth nearly a quarter of
a mile, It is a simple basin, gradually deepening from the west end

THE FRESH-WATER LOCHS OF SCOTLAND. 229

eastwards to the maximum of 20 feet, then shallow at the east end. The
mean depth is 11 feet, the area 119 acres, and the volume 58 millions of
cubic feet. The drainage area, which includes that of the Peerie Water,
measures lj square miles. The outflow is eastward, by the Suso burn,
into the Sound of Rousay.

On September 18, 1906, the surface was 321-5 feet above sea-level. The
temperature at the surface was 54C'6 Fahr., and at 18 feet 54°'0.

Peerie Water (see Plate XCI.) is a very small, narrow, oblong loch,
close to the Muckle Water, in the island of Rousay. On the south rises a
heather-clad hill, on the north a flat rugged moor intervenes between
Peerie Water and Muckle Water. Rock was seen only at the west end.
The bottom is stony and free from mud, moss growing in the deepest
parts. The length is half a mile, and the breadth one-sixth of a mile.
The bottom is nearly flat, the mean depth 6 feet, and the maximum 10 feet.
The area is about 38 acres, and the volume 11 millions of cubic feet. The
drainage area measures one-third of a square mile. The outflow is by
a small burn flowing north into the Muckle Water. The level measured
from Muckle Water was 328'25 feet above sea-level.

The temperature at the surface was 53°'5 Fahr., and at 9 feet half
a degree less.

Hoglinm Water (see Plate XCIV.) is a small loch in the southern part
of the island of Hoy, lying among heather-covered hills of about 600 feet in
height. It is a little more than a third of a mile long, and a fifth of a mile
broad, but is by far the deepest loch in Orkney, having a maximum depth
of 57 feet, somewhat west of the centre. It is a simple basin, deeper
towards the west end, and has a mean depth of 26 feet. The superficial
area is about 39 acres, and the volume of water 44 millions of cubic feet.
The drainage area measures scarcely half a square mile. The outflow is
westward by the Hoglinns burn.

From the following table it will be seen that in the fourteen lochs under
consideration 932 soundings were taken, and that the aggregate area of
the water surface is nearly 10 square miles, so that the average number
of soundings per square mile of surface is 93. The aggregate volume of
water contained in the lochs is estimated at 2321 millions of cubic feet.
The area drained by these lochs is 90J square miles, or about nine times
the area of the lochs.

230

BATHYMETRICAL SURVEY OF

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THE FRESH-WATER LOCHS OF SCOTLAND. 231

THE LOCHS OF SHETLAND.

THE Shetland Islands (see Index Map, Fig. 25) are very different in
their physical features from the neighbouring group of the Orkneys. In
place of the tame undulating surface of Orkney, the Shetlands, though not
higher, are more rugged and more varied. High rocky ridges are separated
by deep valleys, both running north and south. The more varied surface
gives rise to a greater diversity in the lochs. Though many are very
shallow, there is not the unvarying flat-bottomed character of the Orkney
lochs, and some are relatively deep. In some parts of Shetland there are
numerous lochs clustered together, as in North Uist, in other parts there
are few lochs. Of the hundreds of lochs in the islands only thirty-one
were surveyed. Though there are many basins in which there are
numerous lochs, it never happened that we were able to survey more than
two in the same basin, and in so many cases was there only one in the
basin sounded that the thirty-one lochs surveyed occupy twenty-four
separate basins. The area drained by all the lochs surveyed in the islands
is just about 50 square miles, a very small proportion of the whole land
surface. Only eighteen of the lochs have drainage areas of more than a
square mile, eight drain more than 2 square miles, four drain more than
5 square miles, and the Loch of Cliif, with the most extensive drainage
system in Shetland, drains an area of 8J square miles. The combined
superficial areas of all the lochs amount to no more than 4 square miles.
The longest loch in Shetland, measured in a straight line between the
extreme points, is Loch Strom, on the Mainland. Loch Strom has also the
greatest superficial area, a little over half a square mile. The largest body
of water is, however, Loch Girlsta, which, though inferior both in length
and in area to the two lochs, Strom and Cliff, has nearly three times the
volume of water of any other loch in Shetland. The volume of water
contained in all the lochs of Shetland which were surveyed, amounts to
about 1400 millions of cubic feet, which is but little over the volume of
Loch Tummel alone, though that loch is scarcely longer than Loch Strom,
or broader than Loch Spiggie.

The lochs of the Mainland of Shetland number probably some hundreds
of various sizes. The great majority are insignificant in size, and there is
no really large lake in the island. The largest is not 3 miles in length,
the deepest is only 74 feet in maximum depth, and none has a superficial

FI1. 25.— INDEX MAP OF THE SHETLAND ISLANDS.

THE FRESH-WATER LOCHS OF SCOTLAND. 233

area of more than half a square mile. It was only possible to survey
a small proportion of the lochs, as a great many had no boats on them.
Among those surveyed there are some half-dozen somewhat larger lochs
(Lochs Spiggie, Ting wall, Strom, Girlsta, Vaara, and Eela). Lochs in
twenty distinct basins were surveyed, and in six of the basins there were
two lochs surveyed.

The portion of the mainland called North Roe is like North Uist or
Benbecula. The tract containing the lochs is situated to the north of Ronas
hill and towards the west coast. Seen from the top of Black Butten, one
of the summits of Ronas hill, the scene is like that viewed from Lee in
Uist, but of less extent. The lochs are seen thickly studded over a stretch
of rugged, dark moorland some 4 miles long by 3 miles broad. The
moor undulates a good deal between 350 and 500 feet, and most of
the larger lochs are near the latter level. All the lochs in this part
which were surveyed drain independently into the sea, either to north
or west, except Clubbi Shuns and Roer Water, which discharge into Colla
firth on the south-east. The lochs surveyed in this district were Roer
Water, Clubbi Shuns, Flugarth, Muckle Lunga, and Birka.

The two little lochs in the island of Bressay (Brough and Setter) are
the smallest which were surveyed in Shetland. Both lochs are in the same
basin — the Setter basin.

The island of Yell, the second largest island of the archipelago, is
nearly cut in two by the opposite inlets of Whale Firth and Mid Yell
Yoe. There are in the northern half several fairly large lochs, and in the
southern half only a number of smaller lochs. There were no means of
surveying any of these lochs except one very small one, the Loch of
Littlester, at the south end of the island.

The island of Unst is traversed from end to end by a central valley, in
which there are two lochs — the Loch of Watlee (not surveyed), and the
Loch of Cliff, one of the largest lochs in Shetland. There are a good
many smaller lochs, of which one only, the Loch of Snarravoe, was
surveyed.

Sandy Loch (see Plate XCY.) is a small loch on the hill which rises
south-west from Lerwick, and about 2 miles from the town. A steep
heather-clad hill rises on the west ; to the east is a stretch of deep black
peat. Rock was seen on the north and west. The loch is dammed up,
and gives the water-supply to the town of Lerwick. The length is
a little less than half a mile, the breadth a quarter of a mile, the greatest
depth 7 feet. The area is about 46 acres, the drainage area barely one
square mile, and the volume of water 9 millions of cubic feet. The
chief feeder is a burn from the hill of Fitch, and the outflow by a stream
half a mile long into the Yoe of Sound. The level at the date of survey,
August 11, 1903, was 219-85 feet.

The surface temperature was 57 "'9 Fahr.

234 BATHYMETRICAL SURVEY OF

Loch of ClicJchimin (see Plate XCV.) is a very small tidal loch lying
close to the west of the town of Lerwick. The channel to the sea is cut
through a low bar of gravel ; on the west rises a steep hill. The east
and south shores are strewn with boulders, and there are many also in the
loch. A brough or Dim stands on a promontory strewn with stones.

Loch Clickhimin is barely half a mile long, fully a quarter of a mile
wide, and 10 feet in maximum depth, with a mean depth of between 5 and
6 feet. The superficial area is about 46 acres, and the loch drains an area
of half a square mile. The volume is 11 millions of cubic feet. The
bottom is covered with mud, sand, and boulders, and is in parts weedy. It
is said that only high tides enter, and that there are no fish in the loch
except eels.

The surface temperature was 52°'0 Fahr. on July 7, 1903.

Loch of Girlsta (see Plate XCYI.) is a fine large loch of oblong form
situated 6 miles to the north of Lerwick. Its long axis runs north and
south. The shores are desolate heather-covered hills rising on east
and west, higher on the west. There is a broad beach of small grey
stones on east and west, and a sandy beach at the north end. The island
in the loch is low and heather covered. Rock is exposed on the island
and at several spots on the east shore. Near the outflow there is rock in
vertical strata worn to the level of the beach. The outflow, controlled by
a dam and sluice, is through a stony flat southward into Wadbister Voe.

Loch Girlsta is 1^ miles long, and fully one-third of a mile broad in the
middle. Its depth, 74 feet, is the greatest among the lochs surveyed in
Shetland, though it only exceeds Clings Water by one foot. The mean
depth, 31 feet, is the greatest in Shetland. The superficial area, one-third
of a square mile, is exceeded only by Lochs Strom and Cliff, and is about
the same as that of Loch Spiggie. The volume of water, 308 millions of
cubic feet, is nearly three times as great as that of any other loch in
Shetland, the four next largest, Lochs Cliff, Eela, Strom, and Clings Water,
each slightly exceeding 100 millions. Only small burns enter Loch Girlsta,
the largest being the Bretto burn, which drains four small lochs on the
west, and flows into the loch opposite the island. The outflow is on the
south by a mill lead, one-third of a mile long, to the mill of Girlsta. The
area drained is nearly 2 square miles. When surveyed on July 8, 1903,
the loch was 87 -6 feet above sea-level. Except for tfie slight interference
by the shallow water around the island, the basin is very simple, with
approximately parallel contours and even slopes on all sides to the deepest
water in the middle.

The temperature only varied 0*3 degree from surface to bottom ; the
surface temperature being 54°'l Fahr., and at 75 feet 53°*8.

Loch of Burraland (see Plate XCVII.) is situated 4 miles south from
Ollaberry and a little to the east of the main road. There is a farm

.THE FRESH- WATER LOCHS OF SCOTLAND. 235

on the north shore, and all around rough peat, rugged hills to the west,
gently sloping moor to the south, and low land to the east, through
which the Scali burn flows to the Houb, a branch of the Sullom Voe.
The loch measures half a mile in length, from east to west, and is a
fifth of a mile broad. It is very shallow, with a mean depth of
5 feet, and the maximum of 10 feet in the centre. The area is about
53 acres, and the volume of water about 11 millions of cubic feet. The
area drained slightly exceeds a square mile. The level was not ascer-
tained, but is estimated at nearly 100 feet above sea-level. There are
many boulders in the loch, along the east and north shores.
The surface temperature on July 24, 1903, was 55°' 5 Fahr.

Boer Water (see Plate XCVIII.) is the largest of the lochs of North
Eoe. It is nearly in the centre of North Roe, and close to the foot
of Ronas hill on its north-east side. It is of roughly oblong form, and
measures nearly two-thirds of a mile in length, from east to west,
and one- third of a mile in maximum breadth. It is a very shallow
flat basin, with a mean depth of only 10 feet, and all, except two very
small holes, less than 16 feet deep. In one of these holes, towards
the west end, is the maximum depth of 32 feet ; in the more easterly
hollow is a solitary sounding of 27 feet, with shallow water all round.
There is an island near the south-east shore.

Roer Water has a superficial area of about 91 acres, and contains
43 million cubic feet of water. The Burn of Roerwater flows from the
east end of the loch some 2 miles south-eastward into Colla firth. The
drainage area extends to 2^ square miles, and includes many small lochs.
The level at the date of the survey could not be ascertained ; when visited
by the Ordnance Survey on September 28, 1876, the surface was 349 '4
feet above sea-level.

The surface temperature on August 7, 1903, was 54°'8 Fahr.

Clubbi Shuns (see Plate XCVIII.) is a very small loch lying imme-
diately to the west of Roer Water, into which it overflows by a short
stream. It is of irregular form, and measures a little over a quarter
of a mile in length, from east to west, by one-sixth of a mile in greatest
breadth. In area, which is about 16 acres, and in volume, 7 millions
of cubic feet, it is the smallest of the lochs of North Roe. The loch is
very shallow, the greater part of it less than 10 feet deep, only a very
small area, somewhat east of the centre, exceeding 20 feet in depth,
with a maximum of 28 feet. The drainage area, of rather more than
a square mile, includes many very small lochs and the larger Longa
Water, which were not surveyed. The outflow is to the east, the burn
passing through a lower loch of Clubbi Shuns (not surveyed) into Roer
Water. The level could not be ascertained, but would be somewhat over
350 feet.

The surface temperature on August 6, 1903, was 56°'4 Fahr.

236 BATHY METRICAL SURVEY OF

Loch of Flucjarih (see Plate XCIX.) is a small, narrow oblong loch,
running due north and south, and close to the Sand Voe, on the north
coast of the Mainland. It lies amid low country, cultivated to north
and south, at only a few feet above sea-level (determined by the Ord-
nance Survey to be 6'4 feet on October 23, 1876). The axis is slightly
curved. It is half a mile long, by fully one-eighth of a mile in maximum
breadth. The basin is flat-bottomed, with a maximum depth of 8 feet, and
a mean depth of 5 feet. The superficial area is 40 acres, and the volume
of water 8 millions of cubic feet. A considerable stream from the Bergs
of Skelberry (648 feet) enters the south end of the loch, and the outflow,
through Vats meadow, is barely 100 yards long. It drains fully a square
mile of country.

The surface temperature was 58°-0 Fahr. on August 8, 1903.

Muckle Lunga Water (see Plate XCVIII.) is a fairly large loch, of
very irregular form, about a mile to the north of Roer Water, and draining
through a chain of lochs which were not surveyed, into South Wick,
on the west coast of the Mainland. It is longer than Roer Water,
measuring three-quarters of a mile from south to north, but is narrower
(a quarter of a mile in greatest breadth), and of smaller superficial area
(about 58 acres) and volume (17 millions of cubic feet). It is very
shallow, having a mean depth of about 7 feet, and only a very small area
over 10 feet deep, and the maximum of 27 feet, to the east of the centre, in
the broadest part of the loch.

Muckle Lunga is the uppermost of the chain of lochs, and drains a very
small area of only a third of a square mile. The burn flowing out north-
ward to Moosa Water, then westward, changes its name, as is so common
in Shetland, being the Moosawater burn after passing the loch of that
name, and finally the Brettoo burn when tumbling over the cliffs into the
South Wick. The height of the surface above sea-level could not be
measured, but is estimated at somewhere between 450 and 500 feet, being
the most elevated of the lochs surveyed in Shetland.

The surface temperature on August 7, 1903, was 55°*8 Fahr.

Birka Water (see Plate XCVIII.) is a small triangular loch, a short
distance to the north of Ronas hill. It is fully a third of a mile long
from south to north, and a quarter of a mile broad at the extreme
south end. It is a simple basin, the 10-feet contour being close to the
shore except at the angles, the slope of the bottom being gradual to the
20-feet contour, then steeper to the centre, where the maximum depth
of 45 feet occurs. The mean depth is 12 feet, the superficial area about
30 acres, and the volume of water 15 millions of cubic feet. It drains an
area of 3 square miles, receiving most of the water collected on the north
slope of Ronas hill, and the overflow of a large number of lochs. The
burn flows out in the middle of the west side, and, after a course of about

THE FRESH- WATER LOCHS OF SCOTLAND. 237

half a mile, falls over the cliffs into the Lang Clodie Wick. The level
is estimated at just over 400 feet.

The surface temperature on August (3, 1903, was 53°'8 Fahr.

Eela Water (see Plate XCIX. ) is about halfway between Hillswick
and Ollaberry, and close to the main road. It is one of the largest
lochs in Shetland, and nearly square in outline. The loch lies at
a considerable elevation, in the midst of rough moor and low heather-
covered hills, highest to the east. Part of the east shore is rocky, but
the shores are for the most part cumbered with stones and boulders. At
the north-east corner the watershed is close to the loch, and very little
above the level of the water, though the outflow is to the south-west,
by the Eelawater burn, which flows into Hamar Voe on the west coast.
The loch measures three-quarters of a mile diagonally from north-east
to south-west, and is fully half a mile broad at two places — at the extreme
east and a little west of the centre.

Eela Water is a simple basin, the greater part less than 20 feet deep
(mean depth 16 feet), the bottom sloping gently on all sides, the slope
being greatest on the west and south. A limited depression of over
50 feet, with the maximum depth of 54 feet, occurs somewhat north-east of
the centre. The superficial area is not quite a quarter of a square mile, and
the volume of water 103 millions of cubic feet. Only a few very small
burns enter the loch, the area drained extending to scarcely a square mile.
The outflow is through peat, over a channel of boulders, and no rock
was seen near. When surveyed on July 23, 1903, the elevation was
217-9 feet above sea-level ; at that time the water was low, and might rise
3 to 4 feet higher. On October 21, 1876, the Ordnance Survey officers
found the elevation to be 2 18' 7 feet above the sea.

A series of temperatures taken in the deepest part showed a range
of scarcely 1° :— surface, 54°-9 Fahr. ; 25 feet, 54°-6 ; 50 feet, 54°'0.

Funds Water (see Plate XCVII.) is a small loch, lj miles south
of Eela Water, and on the west side of the road. It is surrounded on
all sides by wild heather-covered hills, and peat comes close down to
the stony beach. The islands are low and covered with heather. The
loch is of rhomboid form, half a mile long by a third of a mile broad.
The bottom is very uneven, with several depressions, the deepest of which
lies just north of the largest island, and has a maximum depth of 30 feet.
The mean depth is 10 feet, the superficial area about 40 acres, and the
volume of water 26 millions of cubic feet. It has a small drainage area,
about half a square mile, and receives no considerable stream. The
Pundswater burn flows north-west into Hamar Voe. On July 25, 1903,
the surface was 149-3 feet above sea-level, which is almost identical with
the elevation determined by the Ordnance Survey officers on August 17,

238 BATHYMETRICAL SURVEY OF

1876, viz. 149-4 feet ; the water was low at the time of the survey, and
might rise about 3 feet.

The temperature at the surface was 56°-0 Fahr., and at 25 feet 55°'4.

Loch of Aithness (see Plate C.) is a small loch of triangular form,
draining eastward into Aith Voe. The surrounding land is low, but
on the north the hill rises steeply to 100 feet above the loch. The
loch is half a mile long and a quarter of a mile broad. It forms a
simple basin, with the bottom sloping evenly on all sides to the centre,
and slightly steeper on the north. The maximum depth is 57 feet, and
the mean depth 19 feet. The superficial area is about 58 acres, and
the volume of water 46 millions of cubic feet. The area draining into
the loch is about two-thirds of a square mile. The surface of the water
was 33-7 feet above sea-level on August 29, 1900, when the loch was
visited by the Ordnance Survey; when visited by the Lake Survey on
July 13, 1903, it was fully 2 feet higher, viz. 35*9.

The temperature at the surface was 55°'0 Fahr., at 25 feet 54°-6, at
55 feet 54°-4, a total range of only 0°-6.

Loch of Vaara (see Plate C.) is a fairly large loch in Aithsting, of
oblong form, with its long axis running east and west. The surrounding
moorland rises to no considerable elevation ; hills of a little over 200 feet
lie to the west and south-east. The shores are in part stony, but rock is
exposed at various parts, and at the outflow at the north-west corner,
whence the Vaara burn runs for a quarter of a mile northward into Loch
Clousta. The loch is nearly a mile long and half a mile in greatest
breadth. It forms a shallow basin of flattish bottom, with gently sloping
sides, and the maximum depth of 25 feet almost in the centre. Towards
the shores at various parts many stones and some points of rock show
above the surface. The mean depth is more than half the maximum depth
(or 13J feet). The superficial area is about 128 acres, and the volume of
water 80 millions of cubic feet. The area drained is about 1J square
miles, the chief inflow coming from the south-east by the Mouldry burn.
The surface level on the date of the survey, July 13, 1903, was 25'95 feet,
identical with the level determined by the officers of the Ordnance Survey
on August 22, 1900, viz. 26-0 feet above the sea. The water was low at
the time of the survey, and might rise 3 to 4 feet.

The surface temperature was 54°*4 Fahr.

Loch of Clousta (see Plate C.) is a pretty large loch of rhomboid
form, longest from north to south. The surroundings are moorland —
the shores of the loch chiefly rock. There are many islands of stones
or rock, and many boulders and points of rock, some of them just
submerged. The loch is nearly a mile long, and half a mile broad
at the north end. It is constricted in the middle, where it is only

THE FRESH-WATER LOCHS OF SCOTLAND. 239

one-eighth of a mile wide, and 7 to 9 feet deep. Of the two basins which
lie north and south of the constriction, the northern one is mostly shallow,
with one little hollow of 26 feet deep to the north of the largest island.
The southern basin is triangular in form, and the bottom slopes most
steeply off the promontory on the west, close to which is the maximum
depth of 57 feet. The mean depth is 15 feet.

The area of the loch is about 107 acres, and the volume of water
71 millions of cubic feet, nearly as great as that of Loch Vaara. The
drainage area, which includes Loch Vaara, measures 2| square miles.
Loch Clousta is fed chiefly by the overflow of Loch Vaara. At the
outflow into the North Voe of Clousta is a dam and sluice. On July 11,
1903, the surface was 7'8 feet above sea-level, nearly identical with the
level observed by the Ordnance Survey officers, on September 25, 1877,
viz. 7'9 feet. The range of temperature was less than 1° from surface
to bottom : —

Surface 55°-8 Fahr.

10 feet 55°-8 „

25 „ 55°-5 „

55 „ 55°-0 „

Loch of Hostigates (see Plate C.) is a very small loch in the extreme
north of Aithsting, measuring fully a quarter of a mile long from west
to east, by a fifth of a mile in greatest breadth. Relatively to its small
size it is fairly deep, measuring 41 feet somewhat east of the centre. The
mean depth is 16 feet, the surface area about 19 acres, and it contains
13 millions of cubic feet of water. The drainage area is only one-eighth
of a square mile. A small burn flows out to the north, through another
little loch into Uyea sound. The level could not be determined.

On July 16, 1903, there was a range of temperature of 2°'5 through-
out the body of water, the readings at 20 feet and at 35 feet being
identical : —

Surface 57°-5 Fahr.

10 feet 56°-4 „

20 „ 55°-0 „

35 „ 55°-0 „

Clings Water (see Plate C.) is a loch of moderate size in Aithsting,
draining through the small Loch of Setter (not surveyed) into the Voe
of Clousta. The surrounding moorland rises to heights of from 100 to
fully 150 feet above the loch. In form Clings Water is nearly square,
with a deep bay on the east, and a narrow arm on the west. Though
but a small loch, measuring only two-thirds of a mile long, by fully
one-third broad, it is one of the deepest lochs in Shetland, the maxi-
mum, 73 feet, being only 1 foot less than that of the Loch of Girlsta.
The mean depth is 26 J feet, second only to the Loch of Girlsta. The
superficial area is about 91 acres, and the contents 101 millions of cubic
feet. It receives only surface drainage.

240 BATHYMETKICAL SURVEY OF

On July 14, 1903, the surface-level was 52-9 feet above the sea, almost
identical with the elevation determined by the Ordnance Survey officers on
August 24, 1900, viz. 53'0 feet. The basin is simple, the bottom sloping
on all sides to the deepest water, a little north of the middle line. The
variation of temperature from surface to bottom was only ^° : —

Surface 54°-8 Fahr.

25 feet 54°-6 „

70 .„ 54°-3 „

Grass Water (see Plate CI.) is a narrow loch, to the west of Houllma
Water in Aithsting. It lies amid low moorland, and measures two-thirds
of a mile in length from north to south. The centre line of the loch
is strongly curved. The greatest breadth, one-sixth of a mile, is at
the north end, which is very shallow and obstructed by numerous
boulders. At this end there are several small islands. The narrow
southern portion is slightly deeper, with the maximum depth of 6 feet.
The whole loch is filled with vegetable growth. The superficial area is
34 acres, and the contents 4 millions of cubic feet. The Yoxna burn,
a considerable stream, conveying the overflow of Houllma Water and of
several smaller lochs, enters at the southern extremity, and four or five
smaller burns on the west shore. The outflowing stream passes north-
ward through the little Loch Culeryn into the Vadills, at the head of
Uni firth. The drainage area, including several fairly large lochs
not surveyed, measures 3 square miles. The height of the loch above
sea-level was not ascertained, but it may be estimated from a spot-level
of 11 feet on the shore to be about 10 feet.

The surface temperature on July 15, 1903, was 58°'0 Fahr.

Upper Loch of Brouster (see Plate 01.) is a small loch about 5 miles
south-east from Sandness. It is of oblong form, with the axis running
north and south. It is the lowest of an extensive chain of lochs, stretch-
ing right across the peninsula, from near Sandness to the Browland Voe
near Walls. The chain includes several fairly large lochs, of which only
Burga Water was surveyed, there being no boat on the much larger
Voxterby Loch. The loch is fully one-third of a mile long, one-eighth
of a mile broad, with an uneven bottom, varying from 5 feet to 8 feet in
the centre, and a very small part 11 feet deep near the south end. The
mean depth is 5J feet, the area about 22 acres, and the volume 5 millions
of cubic feet.

The area draining into the loch is 5J square miles. The Brace burn,
from Voxterby Loch, comes in at the north end. A short stream flows
south into the Loch of Brouster, a sea loch, and a branch of the Brow-
land Voe. The level of the loch was not found, but it was stated that the
water might fall a little lower, and might rise 5 to 6 feet higher than on
the date of the survey (July 20, 1903). The surface temperature was
54°-2 Fahr.

THE FRESH- WATER LOCHS OF SCOTLAND. 241

Burga Water (see Plate CI.) lies about 3 miles south-east of Sandness.
It is shaped roughly like the letter T, the stein of the letter running
nearly north -westto south-east, the cross-stroke at right angles to it
at the south end. There are low hills to the north-east, and higher
hills south-westward. Burga Water is one of an extensive chain of
lochs, forming one of the largest lake-systems in Shetland, of which,
however, only two lochs could be surveyed. Its length is fully half a
mile, and the greatest width, across the cross-piece of the T, is very little
less, viz. five-twelfths of a mile. The contours of the bottom are some-
what irregular, the 10-feet contour only nearly following the shore line.
The 2»»-feet contour zigzags from side to side of the loch, unless we
regard the various soundings on which it depends as isolated. Near the
south end is the maximum depth of 31 feet.

The superficial area is 78 acres, the mean depth nearly 13 feet, and the
contents 42 millions of cubic feet. The chief sources of the loch are the
Burn of Cattikismires from the west, and the burn from Mousavord Loch
(not surveyed). Gibbie Laws burn flows from the east corner, lj miles
south-eastward into Voxterby Loch. The area draining into the loch
slightly exceeds 2 square miles. The islands at the south end are all of
rock ; there is rock exposed on the promontory on the west shore, and the
channel leading to the little loch on the east is choked by rock and stones,
so that it could not be entered.

On the date of the survey, July 21, 1903, the surface was 115-65 feet
above sea-level, the water being low at the time, and liable to rise 3 feet
higher, On August 27, 1877, the Ordnance Survey officers found the
elevation to be 116'8 feet above the sea. The range of temperature was
2-4 Fahr.:—

Surface 56°-8 Fahr.

5 feet 56°-l „

10 „ 54°-8 „

15 , 54°-6 „

25 , 54°-4 „

Loch of North-house (see Plate C.) is a loch of moderate size in
Aithsting, about a mile north of Aithsting church. Its general form
is peculiar. There is a main triangular body, with the apex to the
south, from which a narrow arm runs to the north-west. The two
portions are separated by a gravel bar, at the north end of which there is
rock. There is also a bar of rocks near the outflow. The narrow portion
west of the bar has a depth of 7 feet, and is almost flat-bottomed. In the
main loch the maximum depth of 13 feet is at the north end, close to the
gravel bar, and from there it gradually shoals to the south. The total
length is five-sixths of a mile, the greatest breadth one-fifth of a mile.
The mean depth is 6J feet, the area about 58 acres, and the volume 16
millions of cubic feet. The drainage area measures about half a square

B

242 BATHYMETRICAL SURVEY OF

mile ; there are no feeders of any importance, and the Twatt burn conveys
the overflow into Bixter Voe.

On July 17, 1903, the surface was 77'9 feet above sea-level; on
October 24, 1877, the Ordnance Survey officers found it to be 78'7 feet.
The surface temperature was 54°*8 Fahr.

Loch of Collaster (see Plate C.) is a very small triangular loch, lying
1 mile north-west of Aithsting church. It measures fully one-third of a
mile from north to south, by one-fifth of a mile broad at the north end.
It is very shallow, the maximum depth of 10 feet being near the north end.
It receives on the west the Burn of Shunalittle from Loch Shunalittle.
The Twatt burn carries the overflow to Kirkhouse Water (not surveyed),
whence the Burn of Quinigill issues, and, joining the Twatt burn from
the Loch of North-house, enters Bixter Voe. The superficial area is
about 25 acres, the mean depth nearly 6 feet, and the volume of water
7 millions of cubic feet; three soundings in the maximum depth of
10 feet were taken near the northern end. It drains an area of less
than half a square mile. The height of the loch above sea-level could
not be ascertained.

On July 14, 1903, the surface temperatures was 53°'0 Fahr.

Loch of Strom (see Plate OIL) lies 5 miles due north of Scalloway, and
is one of the longest lochs in Shetland, but is very narrow. It is a tidal
loch. Its axis runs nearly due north and south. The valley in which
it lies is here very narrow, and the hills which bound it slope steeply
into the loch. On the east the hills are higher and covered with
heather, and rock shows at many points on. the lake-shore; on the
west the lower hills are rugged and covered with grass ; rock shows
at the promontory called Quoy ness, on the west shore, and at the
extreme south end. South of the Strom bridge the west shore is a terrace
of gravel with boulders. There is rock at the north end of Strom
bridge, and at the sea end of the Strom on the south side. The tide
appears to have little effect on the level of the loch, which was
0'5 foot above sea-level on the date of the survey (August 1, 1903), but it
must renew the water with sufficient frequency to permit of the growth of
fucoids and other marine organisms over the whole of the bottom, even to
the extreme north. The northern part of the loch, rather more than half
the length, is very narrow; south of Quoy ness is a broader portion.
The length is a little over 2J miles, which slightly exceeds that of the
Loch of Cliff, unless the narrow eastern arm is included in the length of
that loch. The greatest breadth, one-third of a mile, is just south of
Quoy ness.

The Loch of Strom is very shallow. East of Quoy ness, on each side
of the narrow island, the depth is only 6 feet, and there is deeper water
both to the north and south. In the northern basin, the central part of

THE FKESH- WATER LOCHS OF SCOTLAND. 243

which is nearly flat-bottomed, but slightly deeper towards the east side, the
greatest depth is 12 feet. In the southern basin the maximum depth of 13
feet is close to Quoy ness, and it gradually shoals to the south end of the
loch. This basin is constricted in the middle by the Castle Holm and a
number of other islands. In superficial area, which is 331 acres, or about
half a square mile, the Loch of Strom is the largest, as it is also the
longest, in Shetland. The low mean depth, 7 feet, gives a relatively small
volume of only 101 millions of cubic feet, which is equalled by one loch
(Clings Water), and exceeded by four lochs (Eela, Cliff, Spiggie, and
Girlsta).

The Loch of Strom has an extensive drainage area, including Sand
Water, and the whole central valley of the Mainland for almost 6 miles
north, or almost as far as Voe. The upper part of this valley, where
the stream flows south from Petta Water, is known as Tetta vale; after
passing through Sand Water it becomes Sandwater burn, and flows into
the north end of the Loch of Strom, under the name of Strom Firth burn.
The drainage area extends to nearly 8 square miles, or about half a square
mile less than that of the Loch of Cliff. The surface temperature varied
from 56°-8 to 57°-2 Fahr. in different parts of the loch.

Loch of Tingwall (see Plate CIII.) is a fairly large loch of oblong
form, 4 miles west of Lerwick, and 2 miles north of Scalloway. It
occupies, with the Loch of Asta, a narrow valley running across the
Mainland, nearly from north to south, between Tax firth and Cliff sound.
The whole west side of the loch is cultivated, with high hills rising
behind; on the east is moorland, with sparse heather. At the north
end is a flat strip of meadow, liable to floods. On the western shore
are a few large boulders and bosses of rock. The island in the centre is
low and covered with heather. The length is just over a mile, and the
greatest breadth nearly a quarter of a mile.

The loch is divided into two nearly equal portions by a constriction,
where it is also very shallow, the depth in the centre of the narrows being
only 9 feet. It is still shallower in the channels on either side of the
island north of the narrows, where the depths are only 2 and 3 feet. The
northern basin is the shallower. It is almost flat-bottomed over the
greater part of the area, with depths of from 7 to 9 feet. In the centre is
a very small and abrupt depression, in which there is a depth of 40 feet.
The southern basin is of a different character ; as shown by the contours,
the sides slope fairly regularly to the centre, where there is the maximum
depth of 60 feet. The mean depth is about 19 feet, the area nearly 107
acres, and the volume of water 87 millions of cubic feet. No large streams
enter the loch ; its outflow is to the south, by a stream about 100 yards
long, into the Loch of Asta. There is rock close to the outflow, on the
west side, and the burn flows among stones, with rock in the channel a
few yards from the loch.

244 BATHYMETRICAL SURVEY OF

On July 2, 1903, the surface was 28'4 feet above sea-level, which is
identical with the level found by the Ordnance Survey officers on July 19,
1876. The temperature varied less than half a degree from surface to
bottom.

Surface. 550>3 Fahr.

10 feet 55°-0 „

25 „ 55°-0 „

55 „ 54°-9 „

Loch of Asia (see Plate CIII.) is a small loch just south of the Loch of
Ting wall, and the surroundings are similar, but the hills are lower, and
there is no marginal flat. There is rock on the west side, towards the
north ; on the east, where there is no beach, and the hill slopes steeply
into the loch, no rock was seen. The burn flows southward about a mile
into Cliff sound, close by Scalloway. There is rock in the stream close
below the loch.

The loch is narrow and elongate from north to south, with a length of
half a mile, and greatest breadth of one-eighth of a mile. It is very
shallow, the greater part less than 6 feet deep, and a single sounding of 13
feet near the north end. The mean depth is 5 feet, the area 32 acres, and
the volume of water 7 millions of cubic feet. The level is barely 2 feet
lower than the Loch of Tingwall, viz. 26*6 feet above sea-level on July 2,
1903, which is nearly identical with that (26'5 feet) determined by the
Ordnance Survey on July 19, 1876. The drainage area, which includes
the Loch of Tingwall, is nearly 2 square miles.

Loch of Brow (see Plate CIV.) is a small triangular loch in Dunrossness,
close to the east end of the Loch of Spiggie. The surrounding country is
low, rising highest on the north. The loch measures half a mile long, by
one-ninth of a mile broad near the east end. It is very shallow and almost
flat-bottomed, with a maximum depth of 6 feet and a mean depth of 2J
feet. It has an area of nearly 45 acres, and contains 5 millions of cubic
feet of water. Two streams enter at the east end, the chief being the Burn
of Hogarth, coming from the north, the area drained being a little over
a square mile. The outflow to the Loch of Spiggie is across a flat boggy
meadow, about one-eighth of a mile across. The level at the date of the
survey (July 3, 1903) was the same as Loch Spiggie, viz. 4-0 feet above
sea-level ; the Ordnance Survey officers found the level on September 1 9,
1876, to be 3'5 feet above the sea.

The surface temperature was 58°'5 Fahr.

Loch of Spiggie (see Plate CIV.) is the only moderately large loch in
the southern part of Mainland. It is approximately oblong in shape, and
its long axis runs nearly north and south. The surrounding land is low,
and there are a number of farms on the shores of the loch. At the north
end are the Sands of Scousburgh. In length it is fourth among the lochs

THE FRESH- WATER LOCHS OF SCOTLAND. 245

of Shetland, measuring 1| miles in a straight line between the extreme
points. The maximum breadth, in the middle, is nearly half a mile.

The loch forms a simple basin, very shallow near the north end. The
bottom slopes very gradually down to 20 feet, after w'uich the slope is
steeper. The area over 30 feet deep is very narrow, and includes a very
small area of over 40 feet founded on a single sounding of 41 feet. The
superficial area is 213 acres, or one- third of a square mile, and the volume
of water, 111 millions of cubic feet, shows the loch to be the third largest
in Shetland. The area drained, including the Loch of Brow, is nearly 6
square miles. The principal streams entering the loch are that from the
Loch of Brow, the Burn of Hillwell near the south end, and the Burn of
Scousburgh in the north. The outflow is though a narrow bar, the Beach
of Spiggie. The surface was only 4*0 feet above the level of the sea on
July 3, 1903, as compared with 3'8 found by the Ordnance Survey on
October 24, 1900.

The temperature was uniform throughout, viz. 56°'8 Fahr.

Loch of Brough (see Plate XCV.) is a very small loch towards the
west side of Bressay. It is the upper loch in the Setter basin, and lies at
an elevation of 75'1 feet between two low hills. This elevation was
determined on June 30, 1903, when the water was very low, and liable to
rise 3 feet higher; when visited by the Ordnance Survey officers on June
14, 1876, the level was 77*6 feet above the sea. It is of oblong form,
measuring nearly one-third of a mile from north to south, by one-eighth of
a mile in greatest breadth, at the north end. It is flat-bottomed, with a
mean depth of 2 feet, and a maximum of 4 feet. The area is 19 acres,
the volume 2 millions of cubic feet, and the drainage area is half a square
mile. A small burn flows a quarter of a^mile north into the Loch of
Setter. There is a deposit of peat and sand on the south-east end of the
loch. The loch was lowered by a drain some years ago, in order to allow
carts to pass along the shore. The surface temperature was 55°'6 Fahr.

Loch of Setter (see Plate XCV.) is a very small loch close to the
shore of the Voe of Cullingsburgh, on the east side of Bressay, at a height
of 43*2 feet above the sea. This elevation was found both- by the Lake
Survey on June 3u, 1903, and by the Ordnance Survey on June 14, 1876 ;
this is practically the lowest level, and the water may rise 3 feet higher.
It is almost circular, measuring one-fifth of a mile in greatest diameter.
It is in all respects by far the smallest loch in Shetland. Its greatest
depth is 2 feet, and its mean depth 1 foot ; the surface area is 14 acres, and
the volume of water, half a million cubic feet, is one-third of that of the
Loch of Brough, the nearest to it in size. The drainage area, which
includes the Loch of Brough, is rather more than a square mile. When
surveyed the loch was much overgrown with weeds. The surface
temperature was 56D>3 Fahr.

246 BATHYMETRICAL SURVEY OF

Loch of Littlester (see Plate CV.) is of somewhat rhomboid form,
longest from west to east, where a shallow arm goes off. It is surrounded
by low heather-covered hills, except at the east end, where a stretch of
flat meadow is covered by crofts. The length is half a mile, by fully
a quarter of a mile broad. The basin is flat-bottomed, with a greatest
depth of 9 feet, and a mean depth of 5 feet. The surface area is about
64 acres, and the volume 13 millions of cubic feet. The drainage area
is barely one-third of a square mile. The burn flows east into the
stream which also drains Loch Kettlester, and enters Burra Voe. The
surface was 34-25 feet above sea-level on August 7, 1903; the Ordnance
Survey determined the elevation on September 28, 1876, as being 34'7 feet
above the sea. On the first-mentioned date the water was low, and might
rise 1J to 2 feet.

The temperature of the surface water was 560<0 Fahr.

Loch of Cliff (see Plate CVI.) is in the northern part of the island of
Unst, and is the most northerly loch in the British Islands. It is a long
and narrow loch, running north and south in the long valley which
occupies the whole central part of Unst from north to south. Near its
northern end a long arm runs to the south-east. The valley in which
the loch lies is at this part very narrow. The hills to the west are high ,
attaining to 558 feet in Libbers hill, heather-clad in the higher parts,
with pasture below. On the east are lower grassy hills; in the bend
formed by the eastern arm and the main loch is a domed heather-covered
hill, the Ness of Queyhouse. The arm is filled with weeds in its eastern
end, and the south end of the loch is also weedy. There is a pile of
stones in the centre of the loch, opposite the opening into the eastern
branch, and another heap, composed of large stones, at the broadest part
of the loch. A bright green flat bars the northern end of the loch, and
through this the Burn of Burrafirth cuts a zigzag course into Burra Firth.
The length of the main loch, measured in a straight line between the
extremities, is 2| miles. This is just a little less than the Loch of Strom.
The eastern arm measures over three-quarters of a mile, following the
centre. The greatest width in the main loch is a little over a quarter of
a mile.

The Loch of Cliff is relatively very shallow ; the maximum depth of
21 feet is in the widest part, and to this the slope is on all sides gradual.
In the narrowest part, towards the north end, the depth in the centre is
only 13 feet, and north of this it deepens slightly to 16 feet. The eastern
arm, except a small portion near the main loch, is less than 10 feet deep.
The mean depth is fully 10 feet, the surface area about 256 acres, and the
volume of water 118 millions of cubic feet, which is only exceeded by that
of the Loch of Girlsta, and is a little greater than that of the Loch of
Spiggie. The drainage area of 8J square miles exceeds that of any other
loch in Shetland and includes the Loch of Watlee, a fairly large loch

THE FRESH-WATER LOCHS OF SCOTLAND. 247

lying 3 miles to the south. The stream which brings the drainage of the
whole central valley of Unst has various names— the Burn of Caldback
where it leaves Loch Watlee, the Burn of Mailand in its middle course,
and the Burn of Baliaster where it enters the loch. On the date of the
survey (August 4, 1903) the surface-level was 5'75 feet above the sea.

The surface temperature in the main loch was 56°'4 Fahr., and in the
eastern branch 56°'3.

Loch of Snarravoe (see Plate CV.) is in the southern part of Unst. It
is a narrowly triangular loch, broadest in the south, its axis running
north-east to south-west. Both shores of the loch are steep grassy slopes,
the west lower and cultivated, the east rising nearly 200 feet above the
loch, and strewn in its lower part with myriads of stones. The largest
burn is that coming in at the north-east end from the Loch of Stourhoull,
half a mile higher up the valley. Some torrents entering on the east
have spread out wide deltas of stones. There is a sparse fringe of reeds
along the west shore. The Burn of Snarravoe flows out at the south-
west corner, and winds through a flat meadow a quarter of a mile north-
westwards into Snarra Voe. There is hardly any beach, and no rock was
seen at the margin of the loch. The upper end is sandy, with some large
boulders. Loch Snarravoe is over half a mile long, and a quarter of a
mile broad at the extreme south. The superficial area is about 53 acres,
the volume of water 27 millions of cubic feet, and the drainage area
three-quarters of a square mile. The basin is simple, the 10-feet contour
closely following the shore. In the centre the depth is only 1 2 feet ;
northwards it deepens slightly to 15 feet; to the south, and close to the
west shore, is a small area over 20 feet in depth, with the maximum
of 29 feet. The surface is very little above sea-level ; on the date of the
survey (August 6, 1903) it was at its lowest, 5*3 feet ; the Ordnance Survey
found the level on November 10, 1876, to be 5'6 feet above the sea.

The temperature of the water was almost uniform throughout —

Surface 55°-2 Fahr.

10 feet 55°-l „

25 „ 55°-l „

From the following table it will be seen that in the thirty-one lochs
under consideration 1707 soundings were taken, and that the aggregate area
of the water surface is nearly 5J square miles, so that the average number
of soundings per square mile of surface is 318. The aggregate volume of
water contained in the lochs is estimated at 1416 millions of cubic feet.
The area drained by these lochs is nearly 52 square miles, or about 9 J times
the area of the lochs.

248

BATHYMETRICAL SURVEY OF

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250

BATHYMETBICAL SURVEY OF

THE RESERVOIRS OF THE FORTH BASIN.

THE principal lochs draining into the Forth were sounded by Sir John
Murray and the late Mr. Fred. P. Pullar, and formed the subject of the
first two papers published in the Geographical Journal in April, 1900, and
March, 1901. The Lake Survey staff subsequently sounded most of the
reservoirs and small lochs around the Firth of Forth, to the number of

to is
). — INDEX MAP OF THE FORTH BASIN.

twenty, of which ten are situated to the south, and ten to the north of the
firth (see Index Map, Fig. 26).

The basins are, for the most part, small and shallow ; only four exceed
a mile in length, and only four exceed 50 feet in depth, while, with one
exception, the superficial area is in each case much less than half a square
mile. The officials of the various waterworks facilitated the work by
providing boats, maps, etc., for the use of the staff, and in this connection
we desire to thank Mr. W. A. Tait, C.E., Engineer of the Edinburgh and
District Water Trust, for many facilities in connection with the Edinburgh

THE FRESH-WATER LOCHS OF SCOTLAND. 251

group of reservoirs, and Mr. Wm. Lockhart, O.E., of the Kirkcaldy and
Dysart Waterworks for tracing of the new reservoir at Holl.

Gladhouse Reservoir (see Plate CVIL), the largest of the Forth
reservoirs, lies at the base of the Moorfoot hills, about 13 miles south of
Edinburgh. It is very irregular in outline, and 1 J miles in length from
south-west to north-east, with a maximum breadth across the middle of
nearly a mile. The superficial area is about 375 acres, or over half a
square mile, and the drainage area about 12 J square miles. The reservoir
is, on the whole, comparatively shallow, 84 per cent, of the floor being
covered by less than 25 feet of water, and only one sounding was taken
in depths exceeding 50 feet, viz. the maximum of 55 feet near the sluice
at the northern end. Here deep water approaches close to the shore in
places, but the bottom is very uneven. The volume of water is estimated
at 269 million cubic feet, and the mean depth at 16J feet.

When surveyed on July 2, 1903, the elevation was 888*6 feet above
sea-level, and temperatures taken in the deepest part gave 60°* 9 Fahr. at
the surface, and identical readings of 58°'0 at depths of 30 and 45 feet.

Eosebery Eeservoir (see Plate CVIII.) lies about a mile to the north
of Gladhouse reservoir, and is extremely irregular in outline. The main
body trends north and south, and is two-thirds of a mile in length ; but
its northern end sends off a branch in a south-easterly direction, so that a
line drawn along the axis of maximum depth from end to end would be
about a mile in length. The maximum breadth is less than a quarter of
a mile, and the superficial area about 52 acres, whilst the area drained,
including Gladhouse reservoir, is about 14 square miles. The maximum
depth of 55 feet was recorded at the junction of the two arms of the
reservoir near the outflow, where there is a small basin exceeding 50 feet
in depth, equal to 11 per cent, of the total area, while 56 per cent, of the
bottom is covered by less than 25 feet of water. The volume of water is
estimated at 58 million cubic feet, and the mean depth at 25*- feet, which
is much greater than the mean depth of Gladhouse reservoir, though the
maximum depth is identical.

When surveyed on June 30, 1903, the elevation was 7 31 '5 feet above
the sea. Temperatures taken in the deepest part showed a range from
surface to bottom of 9°-2 Fahr., and the decrease occurred mostly between
30 and 35 feet, for within this interval of 5 feet of depth a fall of no less
than 7^~ was recorded — equal to a fall of 1^° per foot of depth ; 'while
between 32 J and 35 feet a fall of 4^° was recorded — equal to a fall of
nearly 2° per foot of depth. The readings were as follows : —

Surface 57°'5 Fahr.

30 feet 57°'0 „

32i >? 54o.0

35 „ 49°-5 „

40 „ 48°-5 „

50 , 48°-3

252 BATHYMETRICAL SURVEY OF

Portmore Loch (see Plate CIX.) lies a little more than 2 miles to the
south-west of Gladhouse reservoir, and is two-thirds of a mile in length
from north to south, with a maximum breadth of one-third, and a mean
breadth of a quarter, of a mile. The superficial area is about 105 acres,
and the drainage area exceeds 3 square miles. It is a simple, flat-bottomed
basin, the 10-feet contour closely hugging the shore all round, and the
20-feet contour enclosing an area in the northern harlf equal to one-fourth
of the total area, the maximum depth of 41 feet being recorded about a
quarter of a mile from the north end. The area covered by less than
10 feet of water is one-fifth of the total area, so that about 55 per cent,
of the lake-floor is covered by water between 10 and 20 feet in depth.
The volume of water is estimated at 76 million cubic feet, and the mean
depth at nearly 17 feet. When surveyed on July 4, 1903, the elevation
could not be determined; on December 23, 1892, the Ordnance Survey
officers found it to be 999*0 feet above sea-level. The temperature of the
water was practically uniform throughout, the readings at the surface and
at 20 feet being identical, viz. 57°'5 Fahr., while a reading at 40 feet
gave 57°'l.

Edgelaw Reservoir (see Plate CVIII.) lies about 5 miles to the north-
east of Portmore Loch, and little more than half a mile to the north-west
of Rosebery reservoir. It is elongated and irregular in outline, with
curved axis, trending generally in a west-to-east direction, and is two-thirds
of a mile in length by only one-sixth of a mile in maximum breadth. The
superficial area is only 35 acres, while the drainage area, including Port-
more Loch, exceeds 10 square miles. Though one of the smallest of the
Forth reservoirs, it is the deepest, having a maximum depth near the
outflow of 77 feet, while the mean depth is over 31 feet, the volume of
water being estimated at 47 million cubic feet. The bottom is uneven, a
small 50-feet basin occupying a central position, and being separated by
shallower water from the main 50-feet basin at the east end, where deep
water approaches very close to the shore.

When surveyed on July 7, 1903, the elevation was 650'9 feet above
the sea. Temperatures in the deepest part showed a range of ll°-4 Fahr.
from surface to bottom, but no very rapid fall of temperature is indicated
by the readings : —

Surface 60°-0 Fahr.

15 feet 57°'3 „

30 „ 52°-6 „

70 „ 48°-6 „

Duddingston and St. Margaret's Lochs (see Plate CX.).— These two
small shallow lochs, situated at the base of Arthur's seat in the immediate
neighbourhood of Edinburgh, were sounded. Duddingston covers an area
of about 20 acres and St. Margaret's about 4 acres, the maximum depths

THE FRESH-WATER LOCHS OF SCOTLAND. 253

being respectively 10 and 5 feet, the mean depth in each case being one-
half of the maximum. The volume of water in Duddingston is about
4 million cubic feet, and in St. Margaret's about half a million cubic feet.
They were surveyed on June 27, 1903, when the temperature of the water
in Duddingston was 61°'l Fahr., and in St. Margaret's 60°'7.

Harper rig Reservoir (see Plate CXI.) is situated at the base of the
Pentland hills, about 12 miles south-west of Edinburgh. It exceeds a
mile in length from south-west to north-east, with a maximum breadth
of half a mile, the superficial area being about 226 acres. It is, on the
whole, comparatively shallow and flat-bottomed, with a small area of deep
water near the outflow, the maximum depth of 30 feet being recorded
close to the weir. More than one-half of the bottom is covered by water
between 10 and 20 feet in depth, while only 4 per cent, is covered by
more than 20 feet of water. The volume of water is estimated at
108 million cubic feet, and the mean depth at 11 feet. When surveyed
on July 21, 1903, the elevation was 891-9 feet above sea-level.

ir Reservoir (see Plate CXII.) lies about 4 miles to the
north-east of Harperrig reservoir, and is practically continuous with
Harelaw reservoir, though standing about 25 feet higher. These two
contiguous basins form a perfect contrast in conformation, Threipmuir
covering an area six times greater than that of Harelaw, but being
relatively shallow. Indeed, the south-western portion is merely a swamp.
Threipmuir reservoir is 1J miles in length from south-west to north-east,
excluding a narrow arm branching off to the east ; from the extremity of
this arm to the extremity of the south-western swampy portion is fully
'2 miles. The superficial area is about 192 acres, while the drainage area
exceeds 6 square miles. The maximum depth of 17 feet occurs near the
outflow, whence the water shallows gradually on proceeding to the south-
west or along the narrow arm to the east. The volume of water is esti-
mated at 66 million cubic feet, and the mean depth at 8 feet. When
surveyed on July 1, 1903, the elevation was 831 '5 feet above the sea, and
the temperature of the water was uniform, the reading at the surface being
59-3 Fahr., and at 10 feet 59°-2.

Harelaw Reservoir (see Plate CXII.) is irregular in outline, and exceeds
half a mile in length from south-west to north-east, covering an area of
only 30 acres, and draining an area of 7 square miles, including Threip-
muir. The depth increases gradually on proceeding from the inflow
towards the outflow, where a maximum of 54 feet was recorded. The
volume of water is estimated at 30 million cubic feet (nearly half that
of Threipmuir), and the mean depth at 23 feet (nearly three times that of
Threipmuir). When surveyed on July 1, 1903, the elevation was 806'0
feet above the sea. Temperatures taken in the deepest part gave some

254 BATHYMETEICAL SURVEY OF

interesting results, for from the surface down to 45 feet the temperature was
found to be practically uniform, but between 45 and 47 J feet a fall of
about 5° Fahr. was recorded — equal to 2° per foot of depth — the total
range from surface to bottom being 6°-2. The readings were as follows :—

Surface 58°-5 Fahr.

30 feet 58°-5 „

40 „ 58°-0 „

45 „ 58°-0 „

47* „ ... -. 53°-l „

50 „ 52°-3 „

Linliihgow Loch (see Plate CXIII.) lies close to the town of Linlithgow,
with the ruins of the historic palace standing on its southern shore. It
is nearly a mile in length from north-east to south-west, with a maximum
breadth of a quarter of a mile, the superficial area being about 103 acres.
The promontory on which the palace stands cuts the loch into two halves,
the north-eastern half being flat-bottomed and shallow (maximum 10 feet),
the south-western half deepening from the outflow towards the central
promontory, off which the maximum depth of 29 feet was recorded. The
volume of water is estimated at 34 million cubic feet, and the mean depth
at 7J feet. When surveyed on June 25, 1903, the surface was 149'8 feet
above the sea, practically identical with the elevation (149-9 feet) recorded
by the Ordnance Survey on May 6, 1896. The following temperatures
taken in the deepest part show a range from surface to bottom of 7° Fahr.,
the greatest fall being one of 3° between 10 and 15 feet :—

Surface 62°-2 Fahr.

5 feet 61°-2 „

10 „ 58°-8 „

15 „ 55°-8 „

25 „ 55°-2 „

Gartmorn Dam (see Plate CX1V.) lies less than 2 miles from the
town of Alloa on the northern shore of the Firth of Forth, and is used in
connection with the water-supply to that town. It exceeds a mile in length
from east to west, with a maximum breadth of one-third of a mile, the
superficial area being about 140 acres, and the drainage area nearly 3 square
miles. The water deepens gradually on proceeding from the east end
towards the outflow at the west end, where the maximum depth of 21 feet
was recorded ; nearly half the bottom is covered by less than 10 feet of
water, while nearly 10 per cent, is covered by more than 20 feet of water.
The volume is estimated at 65 million cubic feet, and the mean depth at
lOf feet. When surveyed on May 17, 1905, the elevation could not be
determined from bench-mark, but the scale at the weir showed 17 feet of
water. The following temperatures taken in the deepest part show a range
of 4° Fahr. from surface to bottom, there being a fall of no less than 3°
between the surface and a depth of 5 feet : —

THE FRESH-WATER LOCHS OF SCOTLAND. 255

Surface 60°-0 Fahr.

5 feet 57°-0 „

10 „ 56°-8 „

20 „ 56°-0 „

Peppermill Dam (see Plate CXV.) lies little more than a mile from
Kincardine, on the northern shore of the Firth of Forth, and about 2 miles
from Gartmorn Dam. It is nearly a mile in length from east to west, with
a maximum breadth of a quarter of a mile in the central part, whence it
narrows towards both ends. The superficial area is about 90 acres, and the
drainage area nearly 2 square miles. The eastern portion is shallow, the
water deepening towards the west end, where the maximum of 17 feet was
recorded. The volume of water is estimated at 34 million cubic feet, and
the mean depth at 8J- feet. When surveyed on May 17, 1905, the elevation
was 158-9 feet above the sea, as compared with 160-5 feet found by the
Ordnance Survey officers on September 14, 1894. The following tempera-
tures taken in the deepest part show a range of less than 3° Fahr. from
surface to bottom, a fall of l°-5 Fahr. being recorded between 5 and 10
feet :—

Surface 60°«0 Fahr.

5 feet 59°-5 „

10 „ 58°-0 „

15 „ 57°-3 „

Moor Dam (see Plate CXV.) is a little shallow basin lying between
Peppermill Dam and the town of Kincardine. It is very irregular in out-
line, the maximum diameter from north to south being nearly half a mile,
and the superficial area about 49 acres. Towards the western shore several
soundings in 5 and 6 feet were taken, the northern and eastern parts,
equal to three-fourths of the total area, being less than 5 feet in depth, the
mean depth being estimated at 3j feet, and the volume at 7 million cubic
feet. When surveyed on May 17, 1905, the elevation was 145*4 feet above
the sea, as compared with 146*8 feet determined by the Ordnance Survey
on September 12, 1894. The temperature of the surface water was
60°-5 Fahr.

Burntisland Reservoir (see Plate CXVI.) lies about a mile from Aber-
dour, and less than 3 miles from Burntisland, on the northern shore of the
Firth of Forth. It is most irregular in outline, and about half a mile in
maximum diameter, with a superficial area of about 43 acres. Very deep
water occurs close to the sluice at the southern end, where the maximum
of 39 feet was found, and a small area exceeding 20 feet in depth runs
along the south-eastern shore, but more than half of the bottom is covered
by less than 10 feet of water, the mean depth being estimated at nearly
12 feet, and the volume at 22 million cubic feet. When surveyed on
May 19, 1905, the elevation was 290-0 feet above the sea. The following
temperatures taken in the deepest part show a constant temperature down

256 BATHYMETKICAL SURVEY OF

to 20 feet, and then a fall of no less than 6° Fahr. between 20 and
30 feet :—

Surface 57°'0 Fahr.

10 feet 57°'0 „

20 „ 57°-0 „

30 „ 51°-0 „

Kinghorn Loch (see Plate CXVI.) is a small deep basin about half a
mile from Kinghorn on the northern shore of the Firth of Forth. It
is sub-circular in outline, and about one-third of a mile in maximum
diameter, covering an area of about 30 acres. The basin is simple, with
the maximum depth of 38 feet centrally placed, but towards the southern
shore. The volume of water is estimated at 20 million cubic feet, and the
mean depth at over 15 feet. When surveyed on May 19, 1905, the eleva-
tion was 203*4 feet above the sea, as compared with 205*2 feet found by the
Ordnance Survey on May 4, 1893. The following temperatures taken in
the deepest part show a constant temperature from the surface down to
20 feet, and then a fall of 4° Fahr. between 20 and 30 feet :—

Surface 55°-0 Fahr.

10 feet 55°-0 „

20 „ ... 55°-0 „

30 „ ... 51°-0 „

Loch Fitly (see Plate CXVI.) lies about 3 miles north of the town of
Dumfermline in Fife, and 5 miles south of Loch Leven. It trends nearly
east and west, and is nearly a mile in length, and practically uniform in
width, the maximum breadth being about one-third, and the mean breadth a
quarter, of a mile. The superficial area is about 143 acres, and the drainage
area about 9 square miles. The loch forms a simple basin, with the deeper
water lying along the southern shore, where an artificial bank has been
built across, off which the maximum depth of 16 feet was found ; the small
part of the loch cut off by the embankment has a maximum depth of
12 feet. The volume of water is estimated at 46 million cubic feet, and
the mean depth at 7J feet, fully two- thirds of the bottom being covered by
less than 10 feet of water. The loch was surveyed on May 12, 1905, when
the elevation was 412'8 feet above the sea, as compared with 413'0 feet
determined by the Ordnance Survey officers on March 22, 1894. The
temperature at the surface was 53°*0 Fahr., and at a depth of 15 feet 52°-0.

Loch Gelly (see Plate CXVI.) lies about 4 miles to the east of Loch
Fitty and about the same distance south-east of Loch Leven. It is a broad,
shallow, flat-bottomed basin, three-quarters of a mile in length from east to
west, by nearly half a mile in maximum breadth. The superficial area is
about 148 acres, and the drainage area about 2J square miles. The
maximum depth is 9 feet, and the mean depth 5 feet, the volume of water
being estimated at 32 million cubic feet. When surveyed on May 11,
1905, the elevation was 351*2 feet above the sea, almost identical with

THE FRESH-VVATER LOCHS OP SCOTLAND. 257

that determined by the Ordnance Survey on July 8, 1893, viz. 351*1 feet.
The temperature at the surface was 51°'0 Fahr., and at 8 feet 50°'5.

Harperleas Reservoir (see Plate CXVI.) lies about 3 miles north-east- of
Loch Leven, on the boundary between Fifeshire and Kinross-shire, and is
used by the Kirkcaldy and Dysart Waterworks. It is a small artificial basin
covering an area of about 40 acres, but relatively very deep, the maximum
depth of 4 1 feet being found close to the eastern shore, while one-third of
the bottom is covered by more than 25 feet of water. The mean depth is
estimated at IS.feet, and the volume of water at 31 million cubic feet.
When surveyed on May 10, 1905, the elevation was 848'35 feet above the
sea. The temperature of the water varied little, the following readings
being recorded : —

Surface 51°-0 Fahr.

10 feet 50°-0 „

20 49°-0 „

36 „ 48°-7 „

Holl Reservoir (see Plate CXVII.) lies about a mile to the south-east
of Harperleas, and has been recently made for the further supply of water
to Kirkcaldy. Ballo reservoir lying between them had been emptied for
repairs in February, 1905, and had very little water in it when visited in
May, 1905. Holl reservoir covers an area of about 45 acres and is
relatively deep, the maximum being 38 feet and the mean 17 feet, while
nearly one-half of the bottom is covered by more than 20 feet of water.
On May 16, 1905, the following temperatures were taken, showing a range
throughout the body of water of 4° Fahr. : —

Surface 530tO Fahr.

lOfeet 52°-2 „

20 „ 49°-5 „

30 „ 49°-0 „

Kilronquhar Loch (see Plate CXVIII.) lies close to the town of Kilcon-
quhar. and about a mile north of Elie on the northern shore of the Firth
of Forth. It is sub-circular in outline, and over half a mile in maximum
diameter, covering an area of about 95 acres. It is a shallow flat-
bottomed basin, the maximum depth being 6 feet and the mean depth

4 feet, the volume of water being estimated at 16 million cubic feet.
When surveyed on May 18, 1905, the elevation was 48 '6 feet above the
sea, as compared with 49'4 feet determined by the Ordnance Survey on
March 19, 1894. The temperature at the surface was 61 °- 5 Fahr., and at

5 feet 61°-0.

258

BATHYMETRICAL SURVEY OF

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THE FRESH-WATER LOCHS OP SCOTLAND. 259

From the table on page 258 it will be seen that in the twenty reservoirs
under consideration 1065 soundings were taken, and that the aggregate area
of the water-surface is about 3 square miles, so that the average number of
soundings per square mile of surface is 355. The aggregate volume
of water contained in the reservoirs is estimated at about 998^ millions
of cubic feet. The area drained by these reservoirs is 43§ square miles,
or about 14 times the area of the lochs.

260 BATHYMETRICAL SURVEY OF

LOCHS OF THE T AY 'BASIN.

THE lochs of the Tay basin were dealt with in papers published in the
Geographical Journal in March, 1901, September and November, 1903, and
January, 1904. Subsequently the Loch of Lindores was sounded.

Loch of Lindores (see Plate CXIX.). — The Loch of Lindores lies 2 miles
south of the Firth of Tay at Newburgh, and is nearly a mile in length
from south-east to north-west, with a maximum breadth of nearly half
a mile. The superficial area is about 110 acres, and the drainage area
over 2 square miles. It is a shallow loch with a maximum depth of only
10 feet, observed in two places, a mean depth of 5 feet, the volume of water
being estimated at 24 million cubic feet. The loch was surveyed on April
15, 1904, when the elevation was 221*09 feet above sea-level, as compared
with 223*8 feet recorded by the Ordnance Survey officers on April 18,
1893.

THE FRESH-WATER LOCHS OF SCOTLAND. 261

LOCHS OF THE LINNHE BASIN.

IN the paper dealing with the lochs of the Lochy basin published in
the Geographical Journal in December, 1906, two lochs on the shores of
Loch Linnhe, Loch Lun da Bhra and Loch nan Gabhar, were included.
When sounding Loch nan Gabhar the surveyor was enabled to sound two
little lochans lying about 2 miles to the east, near the Corran narrows at
Ardgour, which proved to be relatively very deep.

Lochan na h-Eaglais (see Plate CXX.). — Lochan na h-Eaglais (or Church
Loch) is the smaller and shallower of the two, and sub-circular in outline,
about one-sixth of a mile in maximum diameter, and covering an area
of about 10 acres. It forms a simple deep basin, with a maximum depth
of 43 feet, the mean depth being estimated at 23 feet, or more than half
the maximum depth, and the volume of water at 10 million cubic feet.
The loch was surveyed on May 12, 1903, but the elevation could not be
determined. The following temperatures taken in the deepest part show
a range of only 2^o Fahr. : —

Surface 50° -0 Fahr.

10 feet ; 48°-5 „

20 „ 47°-8 „

40 „ 47°-5 „

Lochan Eton Mhic Alastair (see Plate CXX.) is also sub-circular in out-
line, and a quarter of a mile in maximum diameter. There is a deep central
basin with a maximum depth of 74 feet near the south-eastern end, where
the slope is steep. The volume of water is estimated at 45 million cubic
feet, and the mean depth at nearly 40 feet, or more than half the maximum.
Considering its small area the loch is very deep, about 57 per cent, of the
lake-floor being covered by more than 40 feet of water. The loch was
surveyed on May 12, 1903, but the elevation could not be determined.
The floods of the previous February had left a drift-mark 5J feet above
the level at the time of the survey, when the water was near its lowest
level. The following temperatures taken in the deepest part of the loch
show a range from surface to bottom of 3°'5 Fahr. : —

Surface 47C'0 Fahr.

10 feet ... 46°-8 „

25 „ 46°-3 „

50 45°-0 „

65 „ 43--5 „

It is said to freeze over very seldom, aud then only in extremely frosty
weather.

262 BATHYMETRICAL SURVEY OF

LOCHS OF THE CLYDE BASIN.

WITHIN this basin (see Index Map, Fig. 27) seven lochs were sounded
by the Lake Survey staff, including one of the largest and most important
of Scottish fresh-water lochs (Loch Lomond), which is interesting as being
one of the two Scottish inland bodies of water surveyed " in the interests of
navigation" by officers of the British navy so long ago as 1861. The other
loch surveyed at that time was Loch Awe in the Etive basin, to be dealt
with later. With the object of determining what changes in conformation,
if any, had taken place in the interval of over forty years, Loch Lomond
and Loch Awe were sounded in 1903, and the results were carefully com-
pared with those obtained in 1861, as shown in the Admiralty charts
published in 1862 and 1863 respectively. Generally speaking, the depths
recorded by the two surveys, both in Loch Lomond and in Loch Awe,
agree very closely, and it was at first considered that it would be
unnecessary to publish the soundings in these lochs, but ultimately the
Directors decided, in order to render the account of the work of the Lake
Survey complete, to issue the maps of these lochs in the same form as the
other maps accompanying this volume.

To the north of the Firth of Clyde, besides Loch Lomond, two neigh-
bouring small lochs (Geal and Sloy) were sounded, and to the south of the
Firth of Clyde, four lochs were sounded, viz. Kilbirnie Loch, Castle
Semple Loch, Loch Thorn, and Gryfe reservoir, the two last mentioned
being artificial, and connected with the supply of water to the town of
Greenock.

Loch Lomond (see Plates CXXIV. and CXXV.).— Loch Lomond is so
well known that there is no necessity to enter here into a detailed topo-
graphic description ; the beauty of its surroundings, which is enhanced by
the many large islands occupying the wide southern portion, has been
referred to by many writers, and has earned for it the title of " Queen of
Scottish lakes " (see Fig. 35). Briefly, it may be stated that the loch
trends nearly north and south, and in a straight line is about 21 miles in
length, but following the sinuous axis of maximum depth, the length is
nearly 23 miles, Loch Lomond being exceeded in this respect only by
Loch Awe and Loch Ness. The upper northern portion for a distance of
12 or 13 miles from the head of the loch is narrow, mostly less than a
mile across, but to the south of ROBS point the loch opens out, and attains

THE FRESH-WATER LOCHS OF SCOTLAND.

263

a maximum breadth of 5 miles about 3 miles above the exit of the river
Leven at Balloch ; the mean breadth of the entire loch is about 1^ miles.
In superficial area Loch Lomond is the largest of all the Scottish fresh-

5 10 IS 20

FIG. 27. — INDEX MAP OF THE CLYDE BASIN.

water lochs, being estimated to cover 27j square miles; its nearest rival
in this respect is Loch Ness, with 21 J square miles, followed by Loch
Awe with less than 15 square miles. The area draining into the loch

264 BATHYMETKICAL SURVEY OF

is about 270 square miles, or ten times the area of the loch. The maximum
depth recorded by the Lake Survey was 623 feet, while on the Admiralty
chart of Lach Lomond a maximum of 105 fathoms, equal to 630 feet, is
shown, but there is no indication of the level of the water at the time of
the Admiralty survey. The volume of water contained in the loch is
estimated at 92,805 millions of cubic feet, or over one half of a cubic
mile ; in this respect Loch Lomond ranks second among the Scottish
lakes, being exceeded only by Loch Ness, the capacity of which is about
three times greater. The mean depth of the entire loch is estimated at
only 121 £ feet, less than 20 per cent, of the maximum depth, which indicates
that a large proportion of the lake-floor is covered by shallow water. As
a matter of fact, more than two-thirds of the lake-floor is covered by
less than 100 feet of water, as shown in the following table, giving the
approximate areas between the consecutive contour-lines drawn in at equal
intervals of 100 feet, and the percentages to the total area : —

Feet. Acres. Per cent.

0 to 100 11,881 ... 67-6

100 „ 200 2,880 ... 16-4

200 „ 300 974 ... 5-5

300 „ 400 528 ... 3-0

400 „ 500 450 ... 2-6

500 „ 600 767 ... 4-4

Over 600 85 ... 0-5

17,565 100-0

This table shows a gradually decreasing area with increasing depth
down to the 500-feet contour, but then a striking increase in the area is
indicated for the zone between 500 and 600 feet, compared with the two
shallower zones, denoting that the deepest part of the loch partakes of
a flat-bottomed character.

The bathymetrical conditions in Loch Lomond having been so long
known, may be here referred to briefly. The conformation of the entire
loch is complex, but especially so in the wide southern portion, where the
contour lines of depth are sinuous in the extreme, but even the narrow
northern portion, which might be looked upon as a characteristic elongated
Highland loch, is to a certain extent irregular. There are three distinct
50-feet basins, separated by shallow water (1) at the entrance of the
Douglas water, and (2) at the chain of islands consisting of Inchtavanach,
Inchconnachan, Inchmoir, Inchcruim, Inchfad, and Inchcailloch, to the
south of which chain the water is all less than 100 feet in depth. There
are two 100-feet basins, one lying between the chain of islands mentioned
and the entrance of the Douglas water, the other extending northwards
uninterruptedly from the Douglas water delta to near the head of the loch.
There are three 200-feet basins : a small one about a mile from the head
of the loch having a maximum depth of 206 feet, a larger one south of
the entrance of the Douglas water, circling round Koss point, having a

THE FRESH-WATER LOCHS OF SCOTLAND.

265

maximum depth of 217 feet, and the largest one extending from north
of the Douglas water delta as far as Ardvorlich, about 2 miles from the
head of the loch, enclosing all the deeper basins. The 300-feet and
400-feet contours are continuous, and enclose areas respectively over 8
and nearly 7 miles in length, lying to the north of the Douglas water
delta. The 500-feet basin is cut in two portions by a ridge, on which the
greatest depth is 483 feet, crossing the loch just south of Tarbet, the
smaller southern portion being over a mile in length, and having a
maximum depth of 564 feet, while the northern portion exceeds 3 miles
in length and encloses the maximum depth of the loch. The 600-feet
basin is a mile in length, and lies to the north of Tarbet, the maximum
depth of «323 feet having been recorded little more than half a mile to the
north-east of Tarbet island.

The survey of Loch Lomond occupied from May 30 to June 19, 1903.
On commencing work the elevation of the surface of the water was
determined by levelling from two bench-marks as being 23*9 feet above
mean sea-level, and during the progress of the survey the water slowly fell
to the extent of more than a foot, but all the soundings were reduced to
that datum level ; the elevation determined by the officers of the Ordnance
Survey on October 12, 1896, was 26*9 feet above the sea, or 3 feet higher
than on May 30, 1903. A drift-mark measured on June 9, 1903, was
found to be 7J feet above the water surface, so that the range in level is
considerable.

Temperature Observations. — The temperature conditions in Loch Lomond
have been studied by Mr. J. Y. Buchanan and others, and for purposes
of comparison half a dozen serial observations taken during the survey
are given here, arranged geographically from north to south.

SERIAL TBMPEBATUBES IN LOCH LOMOND.

Depth
in feet.

, June 2. Off
Ardvotlich.

June 11. OS
Culness.

June 18. Between
the islands of
Torrinch and

June 16. Be-
tween Creinch
island and

June 19. Off
eastern side of

June 13. Southern
end. Nearly a

Depth 205 feet.

Depth 622 feet.

Inchmoan.

Inchmurrin.

Inchmurrin.

Inchmurrin.

Depth 72 feet.

Depth 60 feet.

p

Depth 62 feet.

0 Fahr.

0 Fahr.

0 Fahr.

0 Fahr.

0 Fahr.

°Fahr.

0

46-0

58-1

57-4

56-6

57-2

59'5

10

45-8

56-6

15

56-6

58-3

20

45-2

57-8

57-2

25

45-2

55-3

30

52-7

56-0

57-0

56-8

35

52-0

40

46-3

__

53-5

52-9

50

44-5

45-8

50-5

51-2

60

—

—

—

55-8

—

49-6

70

—

—

49-4

—

100

44-0

43-8

200

42-8

42-7

300

42-2

400

42-2

500

42-2

600

42-2

—

266 BATHYMETRICAL SURVEY OF

Geal Loch (see Plate OXXIV.) is a small simple basin lying at the head
of Loch Lomond, into which it drains. It is one-third of a mile in length
in a north and south direction, and covers an area of about 28 acres. The
maximum depth of 23 feet was recorded towards the northern end, the
mean depth being estimated at nearly 10^ feet, and the volume of water at
12 million cubic feet.

Loch Sloy (see Plate CXXIV.) is situated about 3 miles south-west from
Ardlui, and about 2 miles to the west of the upper part of Loch Lomond,
the mighty Ben Vorlich rising between them ; while to the west of Loch
Sloy rises Beinn Dubh, and to the south-west Ben Voine and other lofty
peaks. The floor of the loch is rocky, and the hollow in which it rests has
probably been filled up to a large extent by boulders fallen from the steep
slopes of Ben Vorlich and Beinn Dubh ; the outflowing stream flows over
solid rock, and the bed of the loch is undoubtedly a rock basin. The loch
trends from north-west to south-east, and is extremely elongate in outline,
being over a mile in length, but only one-eighth of a mile in maximum
breadth. The superficial area is about 65 acres, of which about 73 per
cent, is covered by less than 10 feet of water, and the drainage area is
extensive, exceeding 6 square miles. The maximum depth of 31 feet was
recorded near the southern end, the mean depth being estimated at over
8 feet, and the volume at 23 million cubic feet. The floor of the loch is
irregular, there being two 10-feet basins, the larger, over half a mile in
length, occupying the southern portion of the loch, separated from the
smaller, a quarter of a mile in length, by a ridge covered by 1 and 2 feet
of water. The loch was surveyed on June 11, 1903, but the elevation
above the sea could not be determined ; judging from spot-levels it
appears to be about 810 feet above sea-level.

Kilbirnie Loch (see Plate OXXXII.) is a broad oblong sheet of water in
the county of Ayr, between the villages of Kilbirnie and Beith, 16 miles
from Glasgow. It lies entirely in cultivated land, the G. and S.W. Eailway
skirts its eastern shore, and the southern end is occupied by ironworks
and chemical works, the debris from which encroaches upon the loch. The
length is over l£ miles, and the greatest breadth is fully one-third of a mile.
The loch is shallow, more than half the area being covered by less than
10 feet of water, and the mean depth is 9J feet. The west side is shallow,
a depression running parallel to the east shore, in which there are two
holes of 24 feet and 30 feet respectively. The area is about 247 acres, or
nearly two-fifths of a square mile, and the volume of water 105 millions of
cubic feet. The drainage area extends to about 2 square miles. The Maich
burn is the chief feeder, entering at the north end. The outflow is by the
Dubb's burn, which flows from the north-east corner of the loch northward
by the bed of the Barr Loch (now drained) into Castle Semple Loch.

On the date of the survey (July 26, 1906) the surface was 100'3 feet
above sea-level.

THE FBESH-WATER LOCHS OF SCOTLAND. 267

Castle Semple Locli (see Plate CXXXIII.) is a fairly large loch, in the
county of Renfrew, about 15 miles west of the city of Glasgow. The
north shore is wooded, and there is a sparse strip of trees on the south
shore also, between the loch and the railway. The loch is of narrowly
triangular form, broadest near the west end, and measures If miles in
length, and a little more than one-third of a mile in breadth. It is
extremely shallow and flat-bottomed, 5 feet in maximum depth, and
2J feet in mean depth. The area is about 203 acres, or one-third of
a square mile, and the volume 22 millions of cubic feet. Castle Semple
Loch receives the drainage of an extensive area (nearly 36 square miles),
chiefly brought from the hills to the west by the river Calder, which
enters the west end of the loch. The Black Cart water issues from
the east end of the loch, and, after flowing 10 miles to the north-east,
enters the Clyde 3 miles north of Paisley.

The level of the surface on May 7, 1896, was found by the Ordnance
Survey to be 89-6 feet above the sea. The temperature was 6u°'0 Fahr.
throughout on July 21, 1906.

Upper Gryfe Reservoir (see Plate CXXXIV.).— The Gryfe reservoir,
which lies 3 miles south of Greenock, and immediately to the east of Loch
Thorn, has been formed by draining the upper portion of the valley of the
Gryfe, and is a part of the Greenock Waterworks. The surroundings are
moorland and pasture. The north shore rises more steeply from the loch.
When full the length is 1| miles, but on the date of the survey (October 8,
1906) the loch was very low, and was only about a mile long. The greatest
breadth at the east end was fully one-third of a mile. The maximum
depth close to the dam was 34 feet, and the mean depth over 17 feet. The
superficial area was about 115 acres, and the volume 87 millions of cubic
feet. The drainage area is 2J square miles. The river Gryfe flows east-
ward about 12 miles, and joins the Black Cart near Paisley. The
elevation was 598*2 feet above sea-level.

LocJi Thorn (see Plate CXXXIV.) is a large artificial loch, the principal
reservoir of the Greenock Waterworks, lying at an elevation of 632-4 feet
above the sea among the hills some 3 miles south of Greenock. It is
surrounded by moorland, and there are one or two farms on the shores.

The loch was very low at the time of the survey (Augnst 16, 1906), and
the large island near the east dam was joined to the shore. The length,
measured in a straight line from north to south, is 1J miles. The axis
of the loch is strongly curved. The greatest breadth, about the middle of
the loch, is half a mile. The depth is greatest in the northern part, and
the maximum depth of 42 feet is near the northern end of the loch. The
mean depth is 19J feet, the area about 331 acres, or half a square mile, and
the volume 277 millions of cubic feet. The drainage area is about oj
square miles.

The temperature was identical (60°'0 Fahr.) at the surface and at 35 feet.

268

BATHYMETBICAL SURVEY OF

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THE FRESH-WATER LOCHS OF SCOTLAND. 269

From the table on page 268 it will be seen that in the ten lochs under
consideration 2593 soundings were taken, and that the aggregate area
of the water-surface is 29^ square miles, so that the average number of
soundings per square mile of surface is 88. The aggregate volume of
water contained in the lochs is estimated at 93,41 o millions of cubic feet.
The area drained by these lochs is 318 square miles, or eleven times the
area of the lochs.

270 BATHYMETRICAL SURVEY OF

LOCHS OF THE ETIVE BASIN.

WITHIN the area draining into Loch Etive (see Index Map, Fig. 28) the
staff of the Lake Survey sounded some twenty lochs, including Loch Awe,
one of the most important of the Scottish fresh-water lochs, which was
surveyed by naval officers in 1861, as already mentioned when speaking
of Loch Lomond, in the Clyde basin, the only other loch in Scotland
surveyed by the Government. Loch Awe has the distinction of being the
longest lake in Scotland, and in comparison with it the other lochs in the
basin are dwarfed into insignificance ; still, Lochs Avich and Tulla are
good- sized basins, exceeding each a square mile in superficial area, but
the remaining lochs are mostly very small. Dubh Lochan, near Kings-
house, drains by the river Etive into the head of Loch Etive ; Loch
Dochard drains into Loch Tulla, and thence by the river Orchy into Loch
Awe ; Lochan na Bi, near Tyndrum, drains by the river Lochy, which
joins the river Orchy just before entering Loch Awe at Dalmally ; Loch
Ederline, near the head of Loch Awe, Loch Avich, to the west of the
central part of Loch Awe, Lochs an Leoid, an Droighinn, and na Gealaich,
to the west of the lower part of Loch Awe, and the four little hill lochs
near Portsonachan (Lochs Rainbow, Choire na Cloich, Dhu, and Allt na
Mult) all drain into Loch Awe by longer or shorter streams ; Loch Sior
drains into Loch Nant, and thence by the river Nant into Loch Etive at
Taynuilt; the Black Lochs drain by the Lusragan burn into Loch Etive
at Connel ferry, while Lochans nan Rath and na Beithe lie on the north
side of Loch Etive, opposite Connel ferry. The scenery of the district
is very fine, and the fishing in most of the lochs good. Loch Awe
contains salmon and Salmo ferox, as well as trout.

Loch Awe (see Plates CXXII. and CXXITI.).— Loch Awe being so
well known, and the depth conditions having been known since the pub-
lication of the Admiralty chart in 1863, no lengthy description is called
for here. It is extremely elongate, but sinuous, in outline, and is peculiar
in that a long narrow arm branches off at right angles to the main axis,
and leads through the Pass of Brander to the outflow (see Fig. 36). As
already indicated, Loch Awe exceeds in length all other Scottish fresh-water
lochs, for measured along the central axis from the head of the loch to the
exit of the river Awe, in the Pass of Brander, it is almost 25 J miles in length.
Even excluding the narrow arm, and measuring from the head of the loch

THE FRESH-WATER LOCHS OF SCOTLAND.

271

to the entrance of the river Orchy, the length exceeds 24 miles, and is
nearly equal to the length of Loch Ness (including Loch Dochfour),
which most nearly approaches it in this respect. The loch is, on the
whole, very narrow — less than a mile across, except at the junction of the
narrow arm with the main body, where, measured in certain directions,

English Mile*

FIG. 28.— INDEX MAP OF THE ETIVE BASIN.

the width may be said to exceed 2 miles ; bnt at other places the width
diminishes, and at one point is barely a quarter of a mile. The mean
breadth of the entire loch is about half a mile, or only 2'3 per cent, of
the length — the smallest percentage observed in any of the lochs sounded
by the Lake Survey, recorded also for East Loch Scadavay in North Uist,
followed by 2-5 per cent, for Loch Shiel, and 3 per cent, for Loch Shin.

272 BATHYMETRICAL SURVEY OF

The superficial area is nearly 15 square miles, which places Loch Awe
third in this respect among the Scottish lakes, being exceeded only by
Loch Lomond with 27 J square miles, and Loch Ness with 21^ square
railes.

Loch Awe was surveyed on May 9 to 22, 1903, and during this time
the level of the water varied to the extent of about 2 feet, the highest
level, as measured from bench-mark, being 117'9 feet above the sea,
and to this level all the soundings on the map have been reduced. It
is interesting to note that this elevation is identical with that determined
by the naval officers during their survey in 1861, so that the depths
shown on the Admiralty chart are strictly comparable with those shown
on the Lake Survey map now published. Thus the maximum depth
given on the Admiralty chart is 51 fathoms, or 306 feet, four soundings
at this depth being indicated between 4 and 5 miles from the head
of the loch, while the maximum depth recorded by the Lake Survey is
307 feet, two soundings being taken at this depth in a similar position.
As regards maximum depth, Loch Awe is exceeded by fourteen Scottish
lakes, and as regards mean depth, which is estimated at 105 feet, Loch
Awe is exceeded by nineteen Scottish lakes. The volume of water in
Loch Awe is estimated at 43,451 millions of cubic feet, which is exceeded
by only four Scottish lakes (Lochs Ness, Lomond, Morar, and Tay).

The floor of Loch Awe is uneven, as will be seen from the longitudinal
section along the axis of maximum depth placed at the foot of the map.
Some of the cross-lines of soundings also show irregularities of the bottom.
The 50-feet contour-line is continuous, and coincides, on the whole, with
the outline of the loch, extending nearly from end to end. The 100-feet
contour encloses three separate areas — (1) the largest extending from
little more than a mile from the head of the loch to near the islands at
the junction of the arm at the Pass of Brander, a distance of about 18
miles ; (2) frhe second, extending from about half a mile from the entrance
of the river Orchy into the arm at the Pass of Brander, is over 4 miles
in length ; and (3) the smallest, based on soundings in 125 and 128 feet,
in the Pass of Brander, separated from the second area by a depth of
86 feet. The 200-feet contour encloses no fewer than five separate
areas : (1) a very small area based on an isolated sounding in 200 feet
about 2 miles from the head* of the loch, separated from the second area
by a depth of 195 feet; (2) the principal area, including the deepest
water in the loch, about 5^ miles in length, extending from the entrance
of the Kames river to little more than 2 miles from the head of the loch ;

(3) an area about 1 J miles in length at the junction of the main loch with
the arm at the Pass of Brander, having a maximum depth of 249 feet ;

(4) a small area, based on soundings in 207, 217, and 230 feet, lying
between the islands of Innis Chonain and Eilean Beith ; and (5) a small
area with a maximum depth of 234 feet, off Rudha Dubhairt, about 1 \ miles
from the entrance of the river Orchy. It is to be noted that the middle

THE FRESH-WATER LOCHS OF SCOTLAND. 273

portion of the loch between Port-in-Sherrich and Inistrynich — a stretch
of over 12 miles in length — is less than 20o feet in depth, the deepest
sounding recorded between these two places being 196 feet. The 300-
feet contour encloses an area about 1J miles in length, less than 5 miles
from the head of the loch, two soundings at the maximum depth of 307
feet being recorded about half a mile apart.

The following table, giving the approximate areas between the contour-
lines drawn in at intervals of 100 feet, and the percentages to the total
area of the loch, shows that considerably more than one-half of the lake-
floor is covered by less than 100 feet of water : —

Feet. Acres. Per cent.

0 to 100 5474 ... 57-6

100 „ 200 2900 ... 30-5

200 „ 300 1017 ... 10-7

Over 300 114 ... 1-2

9505 100-0

Temperature Observations. — During the progress of the survey four
series of temperatures were taken, which showed a total range throughout
the whole body of water of only 3J° Fahr., as given in the following
table :—

SERIAL TEMPEBATUBEB IN LOCH AWE.

Depth
in feet.

May 11, north-east of
Budba Gainmheine,
in 160 feet.

May -21, between Port- ; Ara_ Q _«,._„,.
sonachan and Tay- ! $** VSaS
chreggan, in 158 feet. ara' m eet'

May 20, between Badan
Tomain and Innis Cho-
nain, in 163 feet.

0 Fahr.

0 Fahr.

0 Fahr.

0 Fahr.

0

45-2

46-1

45-2

47-1

5

45-0

10

46-0

44-4

15

44-1

25

45-8 44-1

46-8

50

43-8

45-6

44-1

45-1

100

43-8

45-2

43-9

44-8

150

43-6

—

43-8

155

44-9

160

—

—

—

44-4

DM Lochan (see Plate CXXVI.).— The name Dubh Lochau is applied
to four little lochs lying about a mile south-east of Kingshouse. They
are all weedy, and only the one lying farthest to the south-east was
surveyed. It takes the form of a V with one limb pointing to the north,
the other to the north-west. The length is a little over a quarter of a
mile, and the superficial area about 17 acres. The maximum depth of
10 feet was found abont 150 yards from the end of the north limb. The
volume of water is estimated at 2 million cubic feet, and the mean depth
at nearly 3 feet. Dubh Lochan was surveyed on May 21, 1903, but the
level could not be determined ; the elevation given on the Ordnance Survey

T

274 BATHYMETEICAL SURVEY OF

map is 1001 [feet above the" sea, though the date is not mentioned. The
temperature of the surface water was 49°- 5 Fahr.

Loch DocJiard (see Plate OXXVII.) lies about 3 miles to the west of Loch
Tulla, into which it drains. There are some huge boulders on the shore,
and the river both on entering and leaving the loch has considerable
volume, silting up having taken place at the inflow, while at the outflow
rock is exposed on both sides. The loch is somewhat irregular in^ outline,
trending east and west, and is about two-thirds of a mile in length. The
superficial area is about 86 acres, and the drainage area nearly 8 square
miles. The maximum depth of 42 feet was recorded near the centre of the
wide part of the loch. The volume of water is estimated at 44 million
cubic feet, and the mean depth at 1 2 feet. The loch was surveyed on May
18, 1903, but the level could not be ascertained, though it was estimated
from spot-levels to be about 735 feet above the sea. The loch is fairly
simple in conformation, the deep water occupying a central position, but a
sounding in 15 feet was taken towards the northern shore, surrounded
by depths exceeding 25 feet. A spit of sand and boulders projects into the
loch from the southern shore, and from its extremity a shoal or causeway,
covered by 2 or 3 feet of water, extends to the western shore ; in close
proximity to this shoal soundings in 17 and 18 feet were recorded.

The surface temperature over the deep part of the loch was 48°'0 Fahr.,
whereas in the shallow bay at the east end the temperature of the surface
water was no less than 0° higher, viz. o40<0.

LocJi Tulla (see Plate CXXVIII.) lies about 8 miles north-west of Tyii-
druni, and only 2 miles to the south of Lochan na h-Achlaise, in the Tay
basin. It trends in a north-east and south-west direction, and is 2^ miles
in length, and nearly a mile in maximum breadth, the mean breadth being
nearly half a mile. The superficial area is about 703 acres, or over a
square mile, and the drainage area about 57 square miles, including Loch
Dochard. The maximum depth of 84 feet was recorded in two places near
the centre of the loch, about a quarter of a mile to the north-east of the
central island. The volume of water is estimated at 1167 millions of. cubic
feet, and the mean depth at 38 feet. The loch was surveyed on April 16,
1903, the elevation above the sea being determined by levelling from bench-
mark as 542'3 feet. According to the hotel-keeper, the water was low at
the time, the range in level being about 6 feet.

The loch is complex in conformation, due largely to the presence of a
small island (Eilean an Stalcair) near the middle of the loch, opposite the
exit of the river Orchy, in the vicinity of which the bottom is irregular,
and the contour-lines sinuous in character. The main body of water lies
to the north-east of the island, where there is a 50 -feet basin nearly 1J
miles in length, enclosing a 75-feet basin over three-quarters of a mile in
length. To the south-west of the island there is a small subsidiary 50 -feet

THE FRESH- WATER LOCHS OF SCOTLAND. 275

basin opposite the entrance of the Allt Bhreacnais, hased on half a dozen
soundings, the deepest in 58 feet. Silting up has taken place at the
embouchures of the inflowing streams, notably at the two ends of the loch ;
to this is evidently due the curious loop in the 25-feet contour at the
western end. In the south-western angle of the loch, where the Allt
Grain enters, lies a little basin with a maximum depth of 24 feet, cut off
from the main loch by the narrows between Eilean Mhic na h-Ainnis and
the western shore, in which the depth is only a foot. The areas between
the contour-lines, and the percentages to the total area, are as follows : —

Feet Acres. Per cent.

0 to 25 263 ... 37-4

25 „ 50 ... 214 ... 30-5

50 „ 75 148 ... 21-1

Over 75 78 ... ll'O

703 100-0

A series of temperatures taken in the deepest part of the loch at
6-10 p.m. indicated a uniform temperature of 41°'0 Fahr. from surface to
bottom. Two surface readings near shore earlier in the day gave 43 "-9
and 44 -1.

Lochan na B\ (see Plate CXXVI.) lies in Argyllshire near the boun-
dary of Perthshire, 10 miles from Dalmally and a mile from Tyndrum, the
road and railway between these places passing along the northern shore.
It is a shallow loch, trending almost east and west, surrounded by swampy
ground covered in places with small trees. It is about three-quarters of a
mile in length, with a maximum breadth of about one-eighth of a mile, and
covers an area of about 39 acres. The maximum depth of 6 feet was
observed near the centre of the loch. The volume of water is estimated at
6 million cubic feet, and the mean depth at over 3 feet. The loch was
surveyed on May 21, 1903, when the elevation was 823'25 feet above sea-
level ; the elevation is given on the Ordnance Survey map as 822 feet, but
the date is not mentioned.

Loclt EdrrJinc (see Plate CXXII.) is situated near the head of Loch
Awe, and is irregular in outline, trending almost north and south. The
loch is nearly two-thirds of a mile in length, with a maximum breadth of
over one-third of a mile, covering an area of about 70 acres, and draining
an area of over 12 square miles. The basin is simple, though the contour-
lines are sinuous in character, the maximum depth of 58 feet being
observed towards the south end. The volume is estimated at 70 million
cubic feet, and the mean depth at 23 feet.

It was surveyed on May 22, 1903, when the elevation was found to be
r_'2'4 feet above sea-level; on June 25, 1864, the Ordnance Survey officers
determined the elevation as 122'0 feet. The temperature of the surface
water was 51°'<> Fahr.

276 BATHYMETRICAL SURVEY OF

Loch Avich (see Plate CXXII.) lies little more than a mile to the west
of the central part of Loch Awe, into which it drains by the river Avich.
It is the largest loch after Loch Awe in the Etive basin, and trends east-
north-east and west-south-west ; it is narrowly triangular in outline, the
east end forming the base and the west end the apex. The length is 3J
miles, and the greatest breadth nearly half a mile. The superficial area is
about 776 acres, or nearly lj square miles, and the drainage area over 11
square miles. The maximum depth of 188 feet was recorded in two places
towards the eastern end. The volume of water is estimated at 3327
millions of cubic feet, and the mean depth at 98 J feet, or more than half
the maximum.

Loch Avich was surveyed on May 26 and 27, 1903, the elevation being
31O85 feet above sea-level, which is identical with the level observed by
the Ordnance Survey on March 3, 1865. The conformation of the loch is
simple, the contour-lines coinciding approximately with the outline. The
50-feet basin is about 3 miles, the 100-feet basin about 2J miles, and the
150-feet basin nearly 2 miles, in length, in each case approaching closer to the
east than to the west end. One of the soundings at the maximum depth
(188 feet) was taken a little more than half a mile, and the other about a
mile, from the promontory called Rudha Barr na h-Earba, at the east end
of the loch. The off-shore slope is in places very steep ; for instance, off
the northern shore, about three-quarters of a mile from the east end,
soundings in 60 and 82 feet were taken close in-shore, the latter only 80
feet off, giving a gradient exceeding 1 in 1 ; and off the south shore, where
the Abhainn Mhor enters, a sounding in 100 feet was recorded about 120
feet off-shore, indicating a gradient of nearly 1 in 1 ; and at the extreme
east end a sounding in 102 feet was taken comparatively close in.

The approximate areas between the contour-lines drawn in at equal
intervals, and the percentages to the total area, are as follows : —

Feet. Acres. Per cent.

Oto 50 230 ... 29-6

50 „ 100 144 ... 18-6

100 „ 150 185 ... 23-8

Over 150 217 ... 28-0

776 100-0

The flat-bottomed nature of the basin, giving the well-marked U-section
characteristic of glacier-eroded rock-basins, is strikingly shown by the
large areas of the deep-water zones, especially of the deepest zone of all,
which is nearly equal to the shore zone, although the interval between the
150-feet contour and the greatest depth is only 38 feet as compared with
50 feet for the other zones.

Temperature Observations. — During the two days devoted to the survey
the surface temperature varied from 50°-8 to 60°'l Fahr. The following
temperatures were taken in the deepest part of the loch at 6 p.m. on
May 27, 1903 :—

THE FRESH- WATER LOCHS OF SCOTLAND. 277

Surface 55-9 Fahr.

5 feet 55°-0

10 „ 50°-5

15 „ 49°-5

25 „ 47°-0

50 „ 45°-l

75 „ 45°-0

100 „ 44°-8

180 „ 44°-l

The range from surface to bottom was 11°'8, the greatest fall being one
of 4-5 between 5 feet and 10 feet, or nearly 1° per foot of depth.

Loch an Leoid (see Plate CXXIII.) lies about 2 miles north-west of Loch
Awe at Kilchrenan, and drains into the neighbouring Loch an Droighinn,
and thence into Loch Awe by the Kilchrenan burn. It is separated from
Loch Nant, distant about half a mile to the west, by a very low-lying
divide, little more than 100 feet above the lochs at its highest part. Loch
an Leoid is almost rectangular in outline, and trends in a north-east and
Bouth-wesfc direction, the length being half a mile, the maximum breadth a
quarter of a mile, and the superficial area about 73 acres. The greatest
depth of 84 feet was recorded near the southern end. The volume of
water is estimated at 114 million cubic feet, and the mean depth at nearly
36 feet. The loch was surveyed on May 22, 1903, the elevation on that
date being 602-2 feet above sea-level, nearly identical with that observed
by the Ordnance Snrvey officers on August 27, 1864, viz. 6U2'1 feet. The
basin is rather irregular ; across the centre of the loch there is a slight
shallowing, with deeper water both to the north and south, a sounding in
79 feet being recorded about 300 yards from the northern shore, and the
deepest sounding in 84 feet about 200 yards from the southern shore.

Temperatures taken in the deepest part show a range of 2°'2 Fahr. from
surface to bottom, the greatest fall being observed between 50 and
75 feet :—

Surface 48°'5 Fahr.

25 feet 48°-2 „

50 „ 47°'6 „

75 „ 46°-3 „

Loch an Droighinn (see Plate CXXIII.). — Loch an Droighinn (or Loch
Wren) lies immediately to the east of, and runs parallel with, its neigh-
bour, Loch an Leoid. It is over half a mile in length, and covers an
area of about 50 acres. The maximum depth of 48 feet is centrally
placed, but rather nearer to the north end. The volume of water is esti-
mated at 32 million cubic feet, and the mean depth at nearly 15 feet.
The loch was surveyed on May 25, 1903, when the elevation was 601*65
feet above sea-level ; when determined by the Ordnance Survey officers
on August 27, 1864, the elevation was 601-0 feet above the sea. There
are two 20-feet basins, the one to the south of the central island having

278 B ATM Y METRICAL SURVEY OF

a maximum depth of 29 feet, the other to the north of the island including
the deepest water in the loch.

The following temperatures taken in the deepest part show a range of
00<9 Fahr., a fall of 4°;8 being recorded between 25 and 45 feet :—

Surface 56°-0 Fahr.

25 feet 53°-9 „

45 „ 49°-l „

Lochan na Gealaicli (see Plate CXXIII.). — This small loch is situated
about a mile to the north-west of Loch Awe, into which it drains at Tay-
chreggan, and is sub-circular in outline, with a maximum diameter of about
one-fifth of a mile, and covering an area of about 1(> acres. Two soundings
were taken at the maximum depth of 25 feet near the middle of the loch.
The volume is estimated at 7 million cubic feet, and the mean depth at
10 feet. It was surveyed on May 25, 1903, but the level could not be
determined. The surface temperature was 59°*0 Fahr.

Portsonaclian Hill Lochs (see Plate CXXIII.).— Four little lochs at an
elevation of 1300 feet and over on the hill to ^the south of Portsonachan
were sounded by members of the Lake Survey staff, while engaged on the
survey of Loch Awe, on May 28, 1903. The most northerly one, called
Rainbow Loch, has a maximum depth of 26 feet ; the neighbouring one, to
the south-west, called Loch Choire na Cloich, has a maximum depth of
20 feet ; the next one, to the south, called Lochan Dhu, has a maximum
depth of 12 feet ; while the most southerly one, called Lochan Allt na
Mult, is the smallest and shallowest of the group, not exceeding 3 feet in
depth.

Sior Loch (see Plate CXXIX.). — The name Sior Loch is applied to
three shallow little lochs about 1J miles to the south-west of Loch
Nant, into which they drain by the Abhainn Cam Linne. They are rapidly
becoming bog — very reedy, with the bottom covered by a thick mass of
vegetation. The middle loch was the only one sounded on June 4, 1903,
as the boat could not be transported to the other basins ; the maximum
depth of 4 feet was observed in several places towards the east end. The
elevation given on the Ordnance Survey map is 733 feet above the sea,
though the date is not mentioned.

Loch Nant (see Plate CXXIII.) lies little more than 2 miles north-west
of Loch Awe at Kilchrenan, but drains northward into Loch Etive. It is
irregular in outline, trending in a north and south direction, and is nearly
a mile in length, with a maximum breadth of one-third of a mile. Its
waters cover an area of about ] 40 acres, and it drains an area exceeding
9 square miles, including Sior Loch. The maximum depth of 92 feet was
recorded in the southern portion of the loch. The volume of water
is estimated at 148 million cubic feet, and the mean depth at over 24

THE FRESH-WAITER LOCHS OF SCOTLAND. 279

feet. The loch was surveyed on May 23, 1903, but the level could
not be determined ; from spot-levels the elevation is apparently about
feet above the sea. There are two deep basins in the loch, the
northern one having a maximum depth of 59 feet, while the southern
one includes the deepest water in the loch. It is curious to note near
the middle of the southern basin a shoal sounding in 22 feet surrounded
by much deeper water, and a short distance to the south an isolated deep
sounding in 70 feet.

The following temperatures taken in the deepest part of the loch show
a range of less than 3° Fahr. from surface to bottom : —

Surface 49°'8 Fahr.

25 feet 49°'3 „

50 „ 48°-9 „

60 „ 47°-9 „

70 ., 47°-0 „

85 „ ... 46°-9 „

Black Lochs (see Plate CXXX.).— The Black Lochs may be looked
npon as three expansions of the Lusragan burn (or rather four, since the
upper loch is cut into two basins), stretching for a distance of about 2 miles
in a north-east and south-west direction. The upper or northern extremity
is about a mile to the south-east of Connel ferry. The basins decrease in
depth on proceeding from north to south, the maximum depth of 36 feet
having been observed close to the north end, while the maximum depth in
the lower half of the upper loch is 32 feet, in the middle loch 27 feet, and
in the southernmost basin 22 feet. The lowest part is blocked for a con-
siderable distance by reeds, which are found also at various places along
both shores up to the head. They were surveyed on May 25, 1903, the
approximate elevation, judging from spot-levels, being about 80 feet above
the sea. The temperature of the surface water was 58°-3 Fahr.

LocJian nan Rath and Lochan na Beithe (see Plate CXXXI.) lie close
to the northern shore of Loch Etive, opposite Connel ferry. They seem to
have been formed by landslips. Lochan nan Rath covers an area of about
14 acres, and is cut into two basins by a ridge across the narrow central
part, on which there is only 2 feet of water. To the south-west of the
ridge a depth of 19 feet was recorded, while the maximum depth of 32 feet
was found to the north-east of the ridge. The temperature of the surface
water on May 26, 1903, was 62°-2 Fahr.

Lochan na Beithe forms a comparatively simple deep basin, covering an
area of about li'» acres. The deepest part lies towards the western shore,
where four soundings exceeding 50 feet (maximum 58 feet) were taken.
The volume of water is estimated at 23 million cubic feet, and the mean
depth at 28 feet, or nearly one-half of the maximum. There is a slight
constriction near the middle, accompanied by a -slight shoaling of the
water. The surface temperature on May 26, 1903, was 58°-4 Fahr.

280

BATHYMETRICAL SURVEY OF

B

H -i

ii

ng

SUMMARY

ls co the

l

--- - -- - - - 9 9 T^ T <f> ^ 9 •* 'P <r

05 6 00 rH 6 rH 05 TH 6 6 CO 6 CO CO CO CM rH t- TH CO Cq
rH CN 1C »O CM rH rHCq rHrHCq t- TH CO 1C CM

Total in
square
miles.

GOCqCOTHCOCOCOOOCQrH CO O 1O b- O 00 O5 XO CM t- OC

rHcpcpgscqcqcpTHcpTH p TH p p co cp op op CM p p

cqrH
rHrH

O O O O

•2 * 00

Jjl?

XOCOCOOCOrHrHi-HCOCq rHrHOO
00 O rH rH O rH CM rH O O OOOO
THOOrHOOrHOOO OOOO OOOOOO

OOiOrH OOOOOOO

cq cq 6 6 <N -'-

Ratio of depth
to length.

rH t- fc- TH TH CM t- CM t- TH >O
00 t- t- TH CM CO t- t- rH rH CO
CMCOCqCOrHrHrH CMrH

co o

O 00
-^ rH

I

OOCjO

CM CO CM CO O 05 TH 10 00 00 rH CM t- O O TH CM b- TH fc- CO

"CMcqoo5 xbt-T— 16 ocbt^rHcoxot-
io TH co co xo TH TH xo xo cq co TH co cq TH

111

**'

CO CO 9 CO TH O Cq Op 10 CM CO t- rH CO
(fqTHlOb-CqOrHlhrHO COOOCOO5
CM CO rH T-I CO rH

I

0>«

43 J3

H4*

eithe, and the Black
ncludes that of Loc

of Lochs Dubh, Sior, Nant, nan Rath,
h an LeSid ; that of Loch Choire na C
d Mid Black Lochs.

10 TH cq rH

6666

cqTHOcocqt-THcoooo5 OOCOTH

CqrHCpOprHCpTHCMrHrH OOO

cq 6 6 6 6 6 6 6 6 6 666

H

I

rH OOCMCM cq o cq co co co »o

CM rHCMrHr-l Cpq5CO»plOCMCM

ib66ci66cb666 6666

COrHCOOOCqiOCiiOrHTH
a5rHr^^HCOXO»OCOXOrH
TH CO rH

rH 05 CO TH 10 rH CO rH rH O5
rH Tfl t> f CO-00 CM •* r-\

cq

eight
above sea.
t.

TH

O

1C

H
ove
Fee

rH OXOOO-rHCO

co co co co co o co

,_| ,H rH rH t- CO _^

I •£ -g-g-g -g-g g

OOOO O O S

,0,0,0,0 ^2^5 '%

hose
Loc

des that o
the East

in this
hinn in
s those

ther
an

* The drainage area of Loch Awe includes that of all th
area of Loch Tulla includes that of Loch Dochard; that of L
Nant includes that of Sior Loch ; and that of the West Black

THE FRESH-WATER LOCHS OF SCOTLAND. 281

From the table on p. 280 it will be seen that in the twenty-one lochs
under consideration 2619 soundings were taken, and that the aggregate
area of the water surface is about 184 square miles, so that the average
number of soundings per square mile of surface is 144. The aggregate
volume of water contained in the lochs is estimated at about 48,451 millions
of cubic feet. The area drained by these lochs is about 307J square
miles, or nearly seventeen times the area of the lochs.

,A LIBRARY