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Digitized by tine Internet Archive
in 2009 with funding from
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http://www.archive.org/details/lakebonneville01gilb
DEPARTMENT OF THE INTERIOR
MONOGRAPHS
United States Geological Survey
VOLUME I
WASHINGTON
GOVERNMENT PRINTING OFFICE
1890
U. 8. GFOLOGICAL SURVEY
SHORE-LINES ON THE NORTH i' °^ ^^^ OQUIRRH RANGE, UTAH.
. H. Holmes.
VoV
w
UNITED STATES GEOLOGICAL SURVEY
J. W. POWELL, DIRECTOR
LAKE BONNEVILLE
BT
GROVE K^RL GILBERT
WASHINGTON
GOVERNMENT PRINTING OFFICE
1890
CONTENTS
Fage.
Letter op Transmittal , xv
Preface xvii
Abstract of Volume xix
C'liAi'TER I. — Introduction 1
Interior Basins 2
The Great Basin 5
History of Investigation.. 12
Tlie Bonneville Basin 2U
Cbronologic Nomenchitnro 22
Chapter II.— The ToPOGRArnic Features of Lake Shores 23
Wave Work 2'J
Littoral Krosion 29
The Sea Cliff 34
The Wave-cut Terrace 35
Littoral Transportat ion 37
The Beach , 39
The Barrier 40
The Subaqueous Kidgo 43
Littoral Deposition 4t)
Eiu bankments 46
The Spit 47
The Bar 48
The Hook 52
The Loop 55
The Wave-built Terrace 55
The V-Torracoand V-Bar .. 57
Drifting Sand ; Dunes 59
The Distribution of Wave-wrought Shore Features 60
Stream Work; the Delta 65
Ice Work ; the Rampart 71
Submergence and Emergence 72
The Discrimination of Sliore Features 74
Cliffs 75
The Cliff of Differential Degradation 75
The Stream Cliff 75
The Coulde Edge 76
The P^ault Scarp 76
The Land-slip Cliff 77
Comparison 77
Terraces 78
The Terrace by Differential Degradation 78
The Stream Terrace 79
The Moraine Terrace 81
VI CONTENTS.
Page.
Chapter II— The Topographic Features op Lake Shores— Continued.
The Fault Terrace 83
The Laud-slip Terrace 83
Comparison S4
Ridges 86
The Moraine 86
The Osar or Kame 87
Comparison 87
The Recognition of Ancient Shores 88
Chapter III. — Shores of Lake Bonneville 90
The Bonneville Shore-line 93
The Question of a Higher Shore- line 94
More Ancient Lakes 98
Outline of the Lake 101
Extent of the Lake 105
Shore Details 106
Embankment Series Ill
Determination of Still- water Level 122
Depth 125
The Map 125
TheProvo Shore-line 126
Outline and Extent 127
Shore Characters 128
Deltas 129
The Underscore 130
Embankment Series 131
The Map 134
The Stansbury Shore-line 134
The Intermediate Shore-lines 135
Description of Embankments 135
Grantsville 135
Preuas Valley 136
The Snow-plow 137
Stockton and Wellsville 137
Dove Creek 137
Comparison of Embankments - 137
Hypothesis of Differential Displacement 140
Hypothesis of Oscillating Water Surface 141
Superposition of Embankments 147
The Snow-plow 147
Reservoir Butte 148
Stockton , 149
Blacksmith's Fork 151
Dove Creek 151
Double Series in Preuss Valley 152
Deltas 153
American Fork Delta 155
Logan Delta 159
Summary - ICG
Tufa 167
R4sum6 161)
Chapter IV.— The Outlet 171
Red Rock Pass 173
Mar.sh Valley 176
The River 176
CONTENTS. VII
Page.
Chaptkr IV.— The Outlet — Continued.
The Gate of Bear Kiver 178
The Question of an Earlier Discharge 180
The Old River Bed 181
Other Ancient Rivers 184
Outlets and Shore-lines 186
Chapter V. — The Bonneville Beds 188
Lower River Bed Section 189
Lemington Section - 192
Upper River Bed Section 194
Yellow Clay 194
First Gravel '- 194
White Marl 195
Lower Sand 195
Second Gravel 195
Upper Sand 196
Upper Gravel 196
Oscillations of Water Level — 196
Height of the First Maximum 199
The Whiteness of the White Marl 200
Source of Material 203
Composition of Lake Water 204
Experiments 205
Deposition by Desiccation 208
Organic Remains 209
Joint Structure 211
Chapter VI.— The History of the Bonneville Basin 214
The Pre-Bonneville History 214
Alluvial Cones and Aridity 220
The Post-Bonne ville History 222
Subdivision of the Basin 222
Snake Valley Salt Marsh , 223
Sevier Lake 224
Salt Bed 225
Rush Lake 228
Great Salt Lake 230
Surveys 230
Depth 230
Gauging 230
Oscillations since 1875 233
Oscillations prior to 1875 239
Changes in area 243
Causes of Change 244
Future Changes 250
Saline Contents 251
Sources of Saline Matter 254
Rate and Period of Salt Accumulation 255
Fauna 258
The General History of the Bonneville Oscillations 259
The Topographic Interpretation of Lake Oscillations 262
Hydrographic Hypothesis 263
Orogenic Hypothesis 263
Epeirogenic Hypothesis 264
The Climatic Interpretation of Lake Oscillations . 265
Opinions on Correlation with Glaciation 265
VIII CONTENTS.
Page.
Chapter VI. — The History of the Bonneville Basin— Coiitintiod.
The Argument from Aualogy 2C9
Recency i!69
Episodal Character 269
Bi partition 270
Genetic Correlation , 275
The EtFect of a Change in Solar Energy 283
The Evidence from Molluscan Life 297
Depauperation and Cold :{00
Depauperation and Salinity 'Ml
The Evidence from Vertebrate Life :50:{
The Evidence from Encroaching Moraines ;;()5
Wasatch-Bouueville Moraines 30G
Siena-Mono Moraines 311
Summary of Chapter 310
Chapter VII. — Lake Bonneville and Volcanic Eruption 319
Ice Spring Craters and Lava Field 320
Pavaut Butte 325
Tabernacle Crater and Lava Field 329
Pleistocene Winds • 332
Funiarolo Butte and Lava Field 332
Other Localities of Basalt 335
Pleistocene Eruptions Elsewhere 3.36
Rhyolite 337
Summary and Conclusions 33s
Chapter VIII. — Lake Bonneville and Diastrophism 340
Evidence from Faulting; Fault Scarps 340
General Features of Fault Scarps 354
Local Displacements versus Local Loading and Unloading 357
Monutaiu Growth 359
Earthquakes 360
Evidence from Shore-lines 362
Measurements 362
Deformation of the Bonneville Shore-liue 365
Deformation of the Provo Shore-line 371
Deformation during the Provo Epoch 372
Postulate as to the Cause of Deformation - 373
Hypothesis of Gcoidal Dcformatiou 376
Hypothesis of Expansion froui Warming 377
Hypothesis of Terrestrial Deformation by Loading and Unloading 379
Evidence from the Position of Great Salt Lake 384
The Strength of the Earth 387
Chapter IX.— The Age of the Equus Fauna 393
The Fauna and its Physical Relations 393
The Paleontologic Evidence 397
Appendix A.— Altitudes and their Determination. By Albert L. Webster 405
Scheme of Tables 405
Trigonometric Data 406
Barometric Data 406
Lake Records 409
Railroad Records 411
Special Spirit-level Determinations 411
Combination of Data 413
Altitudes of Shorelines and their Differences 416
CONTENTS. IX
Page.
Appendix B. — On the Deformation of the Geoid by the Removal, through Evapo-
ration, OF THE Water of Lake Honnevili.e. By R. S. Woodward 4^)1
Appendix C— On the Elevation of the Surface of the Bonnkvillb Basin by Ex-
pansion DUB TO change OF CLIMATE. By R. S. Woodward 42.')
Index 407
TABLES.
Table I. Dimensions of Lakes 106
II. Enibaukinent Series of the Bonueviilo Shore- line 119
III. Analyses of Bouiievillo Sediments 201
IV. Con<len6ed Results of Analyses in Table III 202
V. Mineral Contents of Fresh Waters in the Salt Lake Basin 207
VI. Analysis of Sevier Lake Desiccation-products and Brine 227
VII. Datum Points Connected with the Gau};ing of Great Salt Lake 2;i:(
VIII. Record of the Oscillations of Great Salt Lake 2:{:i
IX. Analyses of Water of Great Salt Lake 203
X. Accumulation Periods for Substances Contained in the Briue of Great Salt Lake 255
XI. Fresh-water SliellH in the Bonueville-Lahontan Area 298
XII. Measurements ci( Fliiminicola fiisea .'502
XIII. Height of tbe Bonneville Shore line at various points 306
XIV. Height of the Provo Shore-line at various points 370
XV. Diftereuce in Altitude of the Bonneville and Provo Shore-lines at various points 372
XVI. Comparison of post-Boinioville, post-Provo, and Provo Deformations 374
XVII. Summary of Paleontolngic Data for the Determination of the Age of the Equus
Fauna 400
XVIII. Differences of Altitude determined by Trigonometric Observations 406
XIX. Ditt'erenoes of Altitude determined by Barometric Observations 408
XX. Reduction of various Lake Gauge Zeros to the Lake Shore Datum' 410
XXI. Gauge Records showing tbe Height of the Water Surface of Great Salt Lake .
at various dates 411
XXII. Differences of Altitude derived from Railroad Survey Records 411
XXIII. Difierences of Altitude by Special Spirit-level Determinations 412
XXIV. Reduction of results to a Comiuon Datum 413
XXV. Comparative Schedule of Altitudes of the Bonneville Shore-line 417
XXVI. Comparative Schedule of Altitudes of the Provo Shore-line 418
XXVII. Comparative Schedule of Altitudes of the Stansbury Shore line 418
XX \' I II. Ditlercuces in Altitude of the Bonneville and Provo Shore-lines 419
XXIX. Difierences in Altitude of the Provo and Stansbury Shore-lines 419
XXX. Values showing relative positions of Level Surface.s in a Lake Basin 425
ILLUSTRATIONS.
Map of Lake Bonneville Folded in back of cover
Page.
Plate I. Shore-liues on the north end of the Oquirrh Range, Utah (frontispiece).
II. The Great Basin and its Lakes — 6
III. Routes of Travel 18
IV. Bar on the shore of Lake Michigan 48
V. A Hook. Dutch Point, Grand Traverse Bay, Lake Michigan 52
VI. Cup Butte, a feature of the Bonneville Shore-line 54
VII. Plats of Looped and V-shaped Embankments 58
VIII. Map of the East .Side of Preu.ss Valley 92
IX. The Pass between Tooele and Rush Valleys, Utah 96
X. Maji of Bay Bars of the Bouueville Shore-line in Snake Valley, Utah 112
XI. Profiles of Bay Bars of the Bonneville Shore-line 116
XII. Map show-in}; the Preseat Hydrographic Divisions of the Bonneville Basin.. 122
XIII. Map of Lake Bonneville, showing its extent at the date of the Prove Shore-
line 128
XIV. Profilesof the Provo Shore-line 132
XV. Map of the Shore Emltanknients near Grautsville, Utah. 134
XVI. Map of the North Group of Shore Embankments in Preuss Valley 136
XVII. Map of the Middle Group of Shore Embankments in Preuss Valley 136
XVIII. Map of the South Group of Shore Embankments in Preuss Valley 136
XIX. Map of the Snow-plow 138
XX. Map of the Pass between Rush and Tooele Valleys, Utah 138
XXI. Map of Shore Bars and Terraces, Welisville, Utah ..: 138
XXII. Map of the Shore Terraces near Dove Creek, Utah 138
XXIII. Comparative Profiles of the Intermediate Shore-lines 138
XXIV. Reservoir Butte from the cast, showing Bonneville Embankments and Ter-
races ---
XXV. Plat of Reservoir Butte 148
XXVI. Map of the Deltas formed in Lake Bonneville by the Logan River 160
XXVII. The Ancient Deltas of Logau River as seen from the Temple 162
XXVIII. Map of the Outlet of Lake Bonneville at Red Rock Pass, Idaho 174
XXIX. Red Rock Pass, the Outlet of Lake Bonneville, as seen from the north 176
XXX. The Gate of Bear River, from the east 178
XXXI. Map of the Old River Bed 182
XXXII. Geological map of a portion of the Old River Bed 194
XXXIII. Comparative map of Great Salt Lake, compiled to show its increase of Area. 244
XXXIV. Climate Curves 246
XXXV. Map of a Volcanic District near Fillmore, Utah 320
XXXVI. View on Great Salt Lake Desert, showing mountains half buried by lake
sediments — 320
XXXVII. Ice Spring Craters ; Bird's-eye View from the west 322
XI
148
XII ILLUSTRATIONS.
P»ge.
Plate XXXVIII. Ice Spring Craters; the Crescent as seen from the Miter 322
XXXIX. The Taliornaclc Crater ami Lava Hed.s, from the north 328
XL. Pavant Uutte from llio south 320
XLI. Map showing the Distrihutiou of Basalt 334
XLII. Map of the Mouths of Little and Dry Cottonwood Canyons, showing Glacial
Moraines anil Taults 'MC
XLIII. Trough produced by Faulting near the month of Little Cottonwood Canyon. 34G
XLIV. Fault Scarp crossing Alluvial Cone, near Salt Lake City 348
XLV. Map showing Lines of recent Faulting 352
XLVI. Deformation of the Honneville Shore-line 3(i8
XLVII. Deformation of the Provo Sliore-line 372
XLVIII. Vertical Interval between the Bonneville and Provo Shore-lines 372
XLIX. Map showing tho Glaciated Districts of the Binini-vilie Basin 374
L. Theoretic Curves of Post-Bon neville Deformation 374
LI. Map of Black Rock and vicinity, Utah, showing the position of the Black
Rock Bench 300
Fig. 1. Sheep Rock, a Sea Clifi' 35
2. Section of a Sea Clitf and Cut-Terrace in Incoherent Material 'Mi
3. Section of a Sea Cliff and Cut-Terrace in Hard Material 3tl
4. Section of a Beach 39
5. Section of a Ciit-and-Bnilt Terrace 40
6. Section of a Barrier 40
7. Section of a Linear Embanlvuieut 49
8. Map of Braddock's Bay and vicinity, New York, showing Headlands conijccted by Bars. 50
y. Map of tlie head of Lake Superior, showing Bay Bars 51
10. Diagram of Lake Ontario, to show the Fitcli of Waves reaching Toronto from different
directions - 53
11. Map of tho Harbor and Peninsula (Hook) at Toronto 54
12. Section of a Linear Embaukmcut retreating Landward 56
13. Section of a Wavobuilt Terrace 56
14. Section of a Delta 68
15. Vertical Section in a Delta, showing the typical Succession of Strata 70
16. Section of a Rampart 71
17. Ideal Section, illustrating the formation of a Moraine Terrace at the side of a Glacier. 82
18. Ideal Section, showing the internal strnctur(M)f grouped Lateral Moraine Terraces 82
19. Ideal Section of Alluvial Killing against Front Edge of Glacier 82
20. Section of resulting Frontal Mcnaine 'I'errace '83
21. Bonneville and Internuiliate Kmliankments near Wellsville, Utah, showing contrast
between Littoral and Subaerial Topography 98
22. Butte near Kelton, Utah 108
23. Bars near George's Ranch, Utah 114
24. Limestone flutte near Redding Spring ; an Island at tho Provo Stage 129
25. Compound Hook of an Intermediate Shore-lino m!;ir Willow Spring, Great Salt Lake
Desert 145
26. General izeil Section of Deltas at the Month of American Fork Canyon 156
27. Partial Section of Deltas .at Logan, Utah 162
28. Section showing succ(!ssion of l.„acustrine and Alluvial Deposits at Lemingtou, Ut.ali. 192
29. The Upper River Bed Section 191
30. Diagram of Lake Oscillations, inferred from Deposits and Erosions 198
31. Sevier Lake in 1S72 227
32. Annual Rise and Fall of tho Water Surface of Groat Salt Lake 239
33. Non-periodic Rise .and Fall of Great Salt l<ako 243
34. Rise and Fall of Water in the Bonneville Basin 262
3.5. First Diagram of Glaciation Theory 289
ILLUSTRATIONS. XIII
Page.
Fig. 36. Second Diiisiaiu of Glacial ion Theory 29'.i
37. Diagram to illustrate the Alternation of Voloimic Eruptiou and Littoral Erosion on
Pavant liiitte 327
38. Section of -I'avant Butte 327
39. Section at Ha.se of I'avant Unite, showing remnant of earlier Tuff Cone 328
40. Theoretic St^ction of Knmarole Bntte 333
41. Uiinderbero; Butte 335
42. Protilesof the Rock Canyon Delta 344
43. Son til Half of Rock Canyon Delta, showing Fault Scarp.s 345
44. Profile of the South Moraine at tln^ Mouth of Little Cottonwood Canyon, .showing the
effect of Faulting 347
45. Profile of Fault Scarps near Big Cottonwood Canyon 347
46. Shored ines and Fault Scarp near Farmington, Utah 350
47. Profile of Fanlt Scarps near Ogileu Canyon, Utah 350
48. Diagram to illustrate theory of Grouped Fault Scarps in Alluvium 355
49. Generalized cross-jirofile of mountains and valleys, illustrating Post-Bon ueville Dias-
tropliic Changes 367
50. Diagram of Post-Bon neville Diastrophic Changes 367
51. Cross-.sectiou of Ideal Lenticular Lake Basins 423
KRRATUM TO PLATE.
Plate XLII. For " Big Cottonwood Cr." read Dry Cottonwood Cr 346
LETTER OF TRANSMITTAL.
United States Geological Survey,
Division of the Great Basin,
Washington, D. C, June 29, 1889.
Sir: I have the honor to transmit herewith the manuscript of a final
report on Lake Bonneville.
To yourself, and to the Hon. Clarence King, under whose direction a
large part of the investigation was conducted, I am indebted not only for
the facilities which have rendered the research possible, but also for never-
failing kindness and encouragement, that have added zest and pleasure to
the work.
Very respectfully, your obedient servant,
G. K. Gilbert,
Geologist in Charge.
Hon. J. W. Powell,
Director U. S. Geological Survey, Washington, D. C.
PREFACE.
When tlie Geological Survey was created, in 1879, it had for its field
of operations the country west of the Great Plains. In its original organi-
zation, under the directorship of Clarence King, the Division of the Great
Basin was established, with headquarters at Salt Lake City, and the Divis-
ion undertook as its first large work the investigation of the Pleistocene
lakes.
Afterward the field of operations of the Survey was extended over the
entire United States, and as the ajjpropriations of funds were not corre-
spondingly increased, a re-organization became necessary. One factor of
that re-organization was the abolition of the Great Basin Division. Its last
field examinations were made in 1883, and the publication of the present
volmne closes its work.
The preparation of the volume was begun before the re-organization,
and many of the plates for its illustration were then engraved. It was
planned to be chiefly descriptive and to be restricted to the single lake
whose name it bears. All general discussions were to be deferred until
many lakes had been studied. But when it became necessary to bring the
work to a close, the plan of publication was changed, and it was determined
to include in this volume such generalizations as were permitted by the
material gathered.
This change of plan is in part responsible for the great delay in the com-
pletion of the manusci-ipt, but the chief cause of delay has been the assump-
tion by myself of new duties before old ones were fully discharged.
Portions of the material of the volume have already received publica-
tion in various ways. An outline of the history of Lake Bonneville appeared
XVII
MON I 11
XVIII PKEFACE.
in the Second Annual Report of the Sm-Ney. A ])ai-tial discussion of the
deformation of the plane of tlic Bonneville shore-line was ])resented to tlie
American Society of Naturalists at its IJoston meeting, ISS"). The Fifth
Annual Report contained a paper on the topographic features of lake shores.
Tlie subjects of the first and second of these publications are here greatly
amplified. The text of the third is in large part repeated in the .second
chapter of this volume; but the sj)ecialist will find new matter on pages
25-26, 30-31, 3:i, 42-4"), nS-fib, 03-65, 71, <S()-,S3. He will also note that
the discussion of rhythmic embankments takes a new form in another
chapter.
To those assistants, colleagues, and fellow students who have contrib-
uted to my store of material I have endeavored to give credit in the pages
of the text, but it has been impossible there to acknowdedge my multifarious
obligations for friendly aid, advice, and criticism. To numerous citizens of
Utah and Nevada I am indebted for substantial favors, and some parts of
the w'ork would have been very difficult ^^'ithout the special facilities afiVirded
by the railways of Utah.
G. K. G.
ABSTRACT OF VOLUME
Chapter I: Introduction. — Diastropliic processes tend to the formation of closed liasins; atmos-
pheric, to tlieir dostriictiou. In arid reijions formative processes jireyai] ; in buiiiid, destruc-
tive.— The Great Basin is tlie chief North American rlistrict of interior drainage, l)nt is inferior
to those of other continents. Its dry climate is caused by certain relations of winds and ocean
cnrrents. — The Pleistocene lakes of the Great Basin have been previously studied liy Stansbnry,
Beckwith, Blake, Simjison, En';e!niann, Whitney, King, HaKUe, Emmons, Maydcn, Bradley,
Poole, Howell, and Pcale. — The Bonneville Basin is the northeastern part of the Great Basin,
and includes one-fourth its area. — The term Pleistocene is preferred to Quaternary, as being less
counotive.
Chapter II: Topographic Keaturks ov Lake Shores. — The waves and shore cnrrents of lakes are
produced by the same winds. They work together in littoral transportation. Where a shore
current is accelerated, littoral erosion occurs ; where it is retarded, littoral deposition. Where
the current departs from the shore a spit is built. — The delta formation has three parts. The
upper and middle parts are coarser than the lower; the bedding of the middle is more highly
inclined than that of the upper and lower. — An adolescent coast is marked by narrow terraces
and absence of shore drift and embankments; numerous embankments mark the mature coast. —
Wave work renders coast lines less tortuous.— Clift's, terraces, and ridges, due to shore processes,
may be distinguished from si miliar features produced otherwise by the study of their forms,
structures, and relations.
Chapter III: Shores of Lake Bonneville. — The Bonneville shore-line is about 1,000 feet above
Great Salt Lake, and compasses an area of 19,7f)0 S(inare miles. The Provo shore-lino contours
the basin 'MH feet lower, and is the strongest marked of all the shore-lines. Between the Bonne-
ville and the Provo are the Intermediate shore-lines. — The synchronism of the entire Bonneville
shore-line is shown by its scries of embankments. — The Intermediate embanknuiuts are ryhthmic
products of the irregular oscillations of the water surface. — Deltas belong chielly to the Provo
shore-line. — Tufas were deposited just below the water surface. — The chronologic order of the
shore-lines is (1) Intermediate, ('-i) Bonneville. (I!) Provo.
Chapter IV : Outlet. — At the level of the Bonneville shore-line the lak(^ overllowed, sending a stream
from the north end of Cache Valley northward to tlieSn;ike River. The sill of the outlet was of
alluvium, but with a limestone ledge beneath. The alluvium w:is easily washed away, and a
prism of water about 37.') feet deep went out by a debacle, lowering the lake to the level of the
limestone ledge. This level coincides with the Provo shore-line.
Chapter V: Bonneville Beds. — Within the circle of the Bonneville shore-line are lake sediments of
the same date. The White Marl, relatively thin and calcareous, lies above the Yellow Clay, rela-
tively thick and aluminous. — They are separated by a plane of erosion, testifying to a dry epoch
between two humid epochs. The calcareous character of the upper member is theoretically con-
nected with the burial of salts during the dry epoch. — The strata contain fresh-water shells of
living species. — They are divided by a system of parallel joints, ascribed to earthquake shocks.
XIX
XX ABSTRACT OF VOLUME.
Chapter VI : History of Bonnkvii.i.f. Basin. — Previous to fho Bonneville history the basin was
.arid. Tlie lirst rise of tlio lake was without overllow, aurl was long maintained ; the Yellow Clay
was then depo.sited. The Becond rise went ilO feet higher, eansing overllow, lint was of shorter
dnration ; tire White Marl was then deposited. The final drjinK divided the basin into a dozen
indi^pendent basins, the largest of which contains Great Salt Lake. Since 1H4.'> that lake has
repeatedly risen .and fallen throngh a range of 10 feet.— The history of Lake Bonneville is par-
alleled by that of Lake Lahontan, and each is connected willi a history of glaeiation in adjacent
iniinntains. This connection, the deiianperatiou of the fossil shells, and an analysis of the climatic
conditions of glaeiation, lead to the conclusion that the lacustrine ejiochs were epochs of relative
cold.
Chaptkr VII: Lakr Boxnkvillkand Volcanic Eruption. —The group of small craters and basaltic
lava fields near Fillmore, Utah, are closely related to the lake history. Somi; eruptions took place
beneath the water of the lake, others since its disappearance, and others again during the inter-
lacustrine epoch. — Numerous basaltic ernptions occurred in the lake area before the lake period,
and at still earlier dates rhyolite was extra va.sated.
Cii.M'Tku VIII: Lakk Bonnevii.lk and Diastropiiism. — Orogenic change during a period subseijueut
to the lake is shown by fault scarps. The formation of fault scarps is accompanicil by earlh-
i|uakes. — Epeirogeuic change during a period snbse<iuent to the lake i.s shown by the deformatiiui
of the planes of {he shore-lines. Under the postulate that the doming of the planes is due to the
drying away of the lake, it is concluded that the strains induced by the unloacling of the areas
exceeded the elastic limit of the material and caused viscous distortion of the earth's crust.
This result, taken in connection with the phenomena of mountain uplift, leads to an estimatB of
the strength of the crust.
Chapter IX: Aok of the Equus Fauxa. — The Equus fauna at its type locality is contained in lake
lieds correlated by physical relations with the up|)erinost of the Lahontan and Bonneville beds,
The fauna, previously called later Pliocene, is thus shown to have lived in late Pleistocene time.
LAKE BONNEVILLE,
BY G. K. GILBERT.
CHAPTER I.
INTRODUCTION.
This volume is a contribution to the hiter physical history of the Great
Basin. As a geographic province the Great Basin is characterized by a dry
climate, by interior drainage, and by a peculiar mountain system. Its later
history includes changes of climate, changes of drainage, volcanic eruption,
and crustal displacement. Lake Bonneville, the special theme of the vol-
ume, was a phenomenon of climate and drainage, but its complete history
includes an account of contemporaneous eruption and displacement.
When the work of the geologist is finished and his final comprehensive
report A\ritten, the longest and most important chapter will be ujion the
latest and shortest of the geologic periods. The chapter will be longest
because the exceptional fullness of the record of the latest period will enable
him to set forth most completely its complex history. The changes of each
period — its erosion, its sedimentation, and its metamorphism — obliterate
part of the records of its predecessor and of all earlier periods, so that the
order of our knowledge of them must continue to be, as it now is, the
inverse order of their antiquity.
The great importance of the chapter on the latest period lies in the
fact that it will contain the key for the decipherment of the records of the
earlier. The records of those periods consist of the products of various
MON I 1 1
2 LAKE BONNEVILLE.
processes of change, and these products are to be intei-preted only through
a knowledge of the processes themselves. Many of the j)rocesses can l)e
directly observed at the pi-eseiit time, and it is by such observation, com-
bined with the study of freshly formed and perfectly pi-eserved pnnhicts,
that the relation of product to process is learned. It is through the study
of the phenomena <^if the latest period that the connection between present
processes of change and the products of ])ast changes is established.
In view of these considerations the lionneville study has been con-
ducted with a double object, the discovery of the local Pleistocene history
and the discovery of the processes by which the changes constituting this
history were wrought.
INTERIOR BASINS.
In physical geography the terms "basin" and "drainage district" are
synonymous, and are used to indicate any area which is a unit as to drain-
age. The basin of a stream is the tract of C(iuntr\- it drains, whether the
stream is a great river or the most insignificant triljutary to a river. We
thus speak of the basin of the Ohio and of the Ijasin of the Mississippi, and
say that the latter includes the former. And it may be said in general that
the basin of any branching stream includes the basins of all its tributaries.
The l)asin of a lake is the tract of country of which it receives the
drainage, and it includes not only the basins of all affluent streams ])ut the
area of the lake itself The term "lake basin" is also aj)plied to the depres-
sion occupied by the water of a lake and limited l)y its .shores, and where
confusion might arise from the double use, the wider sens-i is usually indi-
cated by the adjective "hydrographic" or its equivalent. If the lake has
an outlet its basin is a part of the basin of the effluent stream, but if it has
no outlet its basin is complete in itself, and is Avholly encu'cled by a line of
water-parting. In such case it is called a co>ifi)i(')/f(il, or i)!f('rio>; or eJoscfl,
or shut, or drainless basin.
If an interior basin exists in a climate so arid that the superficial ffow
of water, which constitutes drainage, is only potential and not actual, or
else is occasional only and not continuous, it contains no })erennial lak-'^
and is called a dry basin.
INTERIOR BASINS. 3
The boundaries separating basins are water-partings or divides, and
these are of all characters, from the acute crests of mountain ranges to low
rolls of the plain scarcely discernible by the eye. Interior basins are com-
])letelY encncled by lines of water-parting.
The existence of interior Ijasins depends on two conditions: a suitable
topographic configuration and a suitable climate. The ordinar}^ process of
land sculpture by running water does not produce cup-like basins, but tends
on the contrary to abolish them. Wherever a topographic cup exists the
streams flowing toward it deposit within it their loads of detritus, and if
they are antagonized by no other agent eventually till it. If the cup con-
tains a lake with outlet the outflowing stream erodes the rim of the basin,
and eventually the lake is completely drained.
The work of streams occasionally produces topographic cups by the
rapid formation of alluvial deposits where two streams meet. If the power
of one stream to deposit is greatly increased, or if the power of the other
stream to erode is greatly diminished, the one may build a dam athwart the
course of the other and thus produce a lake basin.
The great agent in the production of lake basins, or the agent which
has produced most of the large basins, is diastrophism,^ and in a majority
of the cases in which basins are partitioned off by the alluvial process just
described, the change in the relative power of the streams is brought about
by diastrophism.
Other basin-forming agencies are volcanic eruption, limestone sinks,
wind waves, dunes, land slides and glaciers. By far the greatest number
of topographic cups are due to glaciers; but with these we are not now
concerned.
The basins of ordinary lakes are distinguished from interior basins by
overflow, and that depends on climate. The rainfall of each basin is or
may be disposed of by three processes: first, evaporation from tlie soil and
'I finil it advantageous to follow J. W. Powell in the use of diastrophism as a general term for
the process or processes of deformation of the earth's crust. The products of diastrophism are conti-
nents, plateaus and mountains, ocean beds and valleys, faults and folds. Diastrophism is coordinate
with voleanism, and is the synonym of displacement and dislocation in the more general of the two
geologic meanings accjuired by each of those words. Its adjective is diastropldc.
It is convenient also to divide diastrophism into orogeny (monntaiu-making) .and epeirogeny
(continent -making). The words epeirogeny and epeirogenic are defined iu the opening paragraph of
chapter VIII.
4 LAKE BONNEVILLE.
from the vegetation supported by it; second, evaporation from a lake sur-
face; third, outflow. If the rainfall is sufficiently small, it is all retiu'ned
to the air l)y evaporation from the s<iil and vegetation, and the Itasin is dry.
If it is somewhat larger, the portion not directly evaporated Jiccumidiitcs in
the lowest depression, forming a lake, from the surface of which evaporation
is more rapid. The area of the lake surface is determined by the area of
the basin, the rainfall and the local rates of evaporation. The basin is
closed so long as a lake sufficient for the purpose of evaporation does not
require such an extent as to cause it to discharge at the lowest point of the
rim. The area enclosed by a contour passing through the lowest point
of the rim, the total area of the basin, and the local climate are tlie tln-ee
factors which determine whether a given topogra})hic cu]) sliall constitute
an interior basin. If the ai-ea of a topographic cup and the area of the
maximum lake it can contain are nearly identical, it may constitute an in-
terior basin in a region of humid climate. If the contom- through the lowest
point of the rim encloses an area very small in comparison with the entire
basin, the maintenance of an outlet is not inconsistent with an arid climate.
If there were no erosion and sedimentation, unchecked upheaval and
subsidence w^ould greatly multiply the number of basins, (^n the contrary,
if all displacement should cease, and the foundations of the earth become
stable, erosion and sedimentation would merge all Ijasins into one. The
actual state of the earth's surface is therefore at once the result and the
index of the continuous conflict Itetween subterranean forces on the one
hand and atmospheric on the othei". The two processes which destroy ba-
sins are conditioned by climate. In an arid basin the in washing of detritus
is slow and there is no outflow to corrade the rim; but with abundant rain-
fall the accumulation of detritus is rapid and corrasion cons])ires Avith it to
diminish the inequality between center and rim. In arid regions, tlierefore,
the formative subterranean forces are usually victorious in their conflict with
the destructive atmos})heric forces, and as a result closed basins abound;
in humid regions the destructive agencies prevail and lake basins are rare.
In the present geologic age it is necessarv to restrict this generalization to
lands in the lower latitudes, because the glaciation of the last geologic period
created an immense number of lake basins in humid regions of high latitude,
and running water has as yet made little pn)gress in their destruction.
TOPOGRAPHY OF THE GREAT BASIN. 5
THE GREAT BASIN.
The major part of the North Amei'ican continent is drained by streams
flowing- to the ocean, but there are a few restricted areas having no out-
ward drainage. The hxrgest of the.se was called by Fremont, who first
achieved an adequate conception of its character and extent, the "Great
Basin," and is still universally known by that name. It Is not, as tlu; title
might suggest, a single cup-shaped depression gathering its waters at a com-
mon center, but a broad area of varied surface, naturally divided into a
large numljer of independent drainage districts. It lies near the Avestern
margin of the continent and is embraced l)y rivers trll^utary to the Pacific
Ocean. On the north it Is Ijounded by the drainage basin of the Columbia,
on the east by that of the Colorado of the West, and on the west by the
basins of the San Joaquin, the Sacramento, and numerous minor streams.
The central portion of the western water-parting is the crest of the Sierra
Nevada, one of the greatest mountain masses of the United States, and far-
ther south high moimtains constitute much of the boundary. The northern
half of the eastern boundary is likewise high, winding through the region
of the High Plateaus. The remainder of the boundary does not follow any
continuous Hue of upland, but crosses mountain ranges and the intervening
valleys without being itself marked by any conspicuous elevations. It is
defined onlv through a study of the drainage. The general form of the
area, as exhibited on Plate II, is rudely triangular, with the most acute angle
southward. The extreme length in a direction somewhat west of north and
east of south is about 880 miles, the extreme breadth from east to west, in
latitude 40° 30', is 572 miles, and the total area is approximately 210,000
square miles. Of political divisions it includes nearly the whole of Nevada,
the western half of Utah, a strip along the eastern border of California and
a large area in the southern part of the State, another large area in south-
eastern Oregon, and smaller portions of southeastern Idaho and soiithwest-
ern Wyoming. The southern apex extends into the territory of Mexico at
the head of the peninsula of Lower California.
The region is occupied by a number of mountain ridges which betray
system by their parallelism and by their agreement in a peculiar structure.
6 LAKE BONNEVILLE.
Their general trend is northerly, inclining eastwiird in the northern p;irt of
the basin and westward at the south. The individual ridges are usually
not of great length, and tliey are so disposed en eclielon that the traveler
winding among them may traverse the Ijasin troni cjist to west without
crossing a mountain pass. The type of structure is tliat (if the faulted mono-
cline, in which the mountain ridge is produced l)y the uptilting of an oro-
genic block from one side of a line of fracture, and it has been named (from
the region) the Basin Range ty})e. Its distribution, however, does not coin-
cide perfectly with the district of interior drainage. On the one hand the
Great Basin includes along its eastern margin a portion of the Plateau
province, with its peculiar structural type, and on the other the Basin Range
province extends southward through Arizona to New Mexico and Mexico.
Between the ranges are smooth valleys, whose alluvial slopes and floors
are built of the debris washed through many ages from the mountains. In
general they are trough-like, but in places they coalesce and assume the
character of plains. The plains occupy in general the less elevated regions,
where an exceptional amount of detritus has been accmnulated. In the local
terminology they are called deserts. The largest are the Great Salt Lake
and Carson deserts at the north and the Mojave and Colorado deserts at the
south. The Escalante, the Sevier, the Amargosa, and the Ralston are of
subordinate importance.
Where the basin is broadest, the general elevation of its lowlands is
about 5,000 feet, but they are somewhat higher midway between the eastern
and western margins, so as to separate two areas of relative depression, the
eastern marked by the Great Salt Lake and Se\'ier deserts, and the Avestern
by the Carson desert. Southward there is a gradual and irregular descent
to about sea-level, and limited areas in Death Valley and Coahuila Vallev lie
lower than the surface of the ocean.
The aridity of the region is shown instrumentally l»y tlie records of
rainfjill and atmospheric humidity. On the broad plain bounded east and
west by the Appalachian Mountains and the Mississi}}pi River, 43 inches of
of rain falls in a year. On the lowlands of the Great Basin there falls Init 7
inches. In the fonner region the average moisture content of the air is 69
per cent of that necessary for saturation; in the lowlands of the Great
U S.GFOLOGICAL SURVBr
LAKJS BONNEVILLE PL. K
Julius Bicn it Co. lith
THE GREAT BASIN .\ND ITS LAKES
CLIMATE OF THE GREAT BASIN. 7
Basin it is 45 per ceiit.^ From the surface of Lake Micliigan evaporation re-
moves each year a layer of water 22 inches deep.^ The writer lias estimated
that 80 inches are yearly thus removed from Great Salt Lake,^ and Mr.
Thomas Russell has computed from annual means of temperature, vapor
tension, and wind velocity that in the lowhuids of the Great Basin the an-
nual rate of evaporation from water surfaces ranges from GO inches at the
north to 150 inches at the south.^
The variation with latitude exhibited by the evaporation is found also,
inversely, in the rainfall, but is not clearly apparent in the humidity. In
the southern third of the Basin the lo'\\land rainfall ranges from 2 to 5 inches.
On the line of the Central Pacific Railroad, between the 40th and 42d par-
allels, it averages 7 inches; in the Oregonian arm at the north, 15 inches.
The average lowland precipitation for the whole area is between 6 and 7
inches. With the relative humidity approximately constant, the evapora-
tion rate varies directly and the rainfall inversely with the temperature, and
both latitude and altitude here make the lowland temperature fall toward
the north. The sympathy of rainfall with temperature is likewise shown in
the greater precipitation of the mountains as compai-ed with adjacent valleys.
Mountain stations proper are wanting, but rain-gauge records on the flanks
and in the passes of mountains shoAV a marked ad^s-antage over those in
neighboring lowlands. An estimate based on these, on the records at high
points in the Sierra Nevada, and on approximate knowledge of the heights
and areas of the mountains and plateaus of the Great Basin, places the
average precipitation for the whole district at 10 inches.
The story of climate is more eloquently told by the hydrography and
the vegetation. In the valleys of the northwestern ann of the basin there
are numerous lakes, drainless and of varying extent, but fed by streams
from mountain ranges of moderate size. In the middle region the only per-
ennial lakes are associated with mountain masses of the first rank. The
'Those figures aud those in the preceding sentences are based ou data compiled hy the U. S. Sig-
nal Service. TInongh the courtesy of Gen. A. W. Greely, Chief Signal Officer, the writer has had
access to manuscript data as well as printed.
■=D. Fiirrand Henry, in a report ou the meteorology of the Laurentiau lakes. Kept, of Chief of
Engineers for the year 18G8. Washington, 1800, p. 980.
'Report on the lands of the Arid Regiou . . . , J. W. Powell, 2d ed., Washington, 1879, p. 73.
*MS. report to the Chief Sigual Officer.
8 LAKE BONNEVILLE.
great Sierra forming the western wall of the basin receives each winter a
heavy coating of snow — the greater ])art on the side of the great Califoniian
valley, but enough east of the water-parting to maintain a line of lakes in
the marginal valleys of the Great Basin. The Wasatch range and its asso-
ciated plateaus, overlooking the Basin from the east, are less favored than
the Sierra, but still receive an important precipitation, and by gathering the
drainage from a lai'ge area, support Great Salt Lake, the largest of the Ba-
sin's water .sheets. The East Humboldt Range, standing raidwav, and one
of the largest mountain masses within the basin area, catches enough moist-
ure to feed at one base two small lakes and at the other the Hundjoldt
River. The neighboring and smaller mountains are whitened every winter
by snow, a large share of which either evaporates ^\itliout melting or, if
melted, is al)sorbed by the soil, to be returned to the thirsty air without
gathering in drainage ways. Many of them are Avithout perennial streams;
some even lack springs; and of the mountain creeks, few are strong enough
to reach the valleys before succumbing to the ravenous desert air. The
Hmnboldt itself, though fairly entitled to the name of river, dwindles as it
goes, so that its remnant after a course of two hunch'ed miles is able to sus-
tain an evaporation lake barely twenty-five square miles in extent. Most
of the small closed basins are without ])ermaneut creek or lake, containing
at the lowest point a playa or "alkali flat" — a bare, level floor of fine saline
earth, or perhaps of salt, over which a few inches of water gather in time
of storm.
In the southern half of the Basin there are no lakes dependent for their
water on the interior ranges. At the east the most southerly lake is Sevier,
in latitude 3!)°; the last of the lakes sustained by the Sierra is Owens, be-
tween the Sfitli and 37th parallels. Then for three hundred miles evapora-
tion is supreme. Playas abound, streams are almost unknown, and springs
are rare. Death Vallev, with its floor of salt spread lower than the surtace
of the ocean, is overlooked on either side by mountains from .5, 000 to 10,000
feet high, but they yield it no flowing .stream, and more than one traveler
has perished from thirst while endeavoring to pass from spring to spring.
The Mohave "river" is a hundred miles long, but it preserves its life oidy
by concealment, creeping through the gravel of the desert and betraying
CLOUD-BURST CHANNELS. 9
its existence only where ledj^-es of rock athwart its conrse force it to tlie
surface.
As in other desert regions, precipitation here resuhs only from cyclonic
disturbance, either broad or local, is extremely irregular, and is often vio-
lent. Sooner or later the "cloud-burst" visits eveiy tract, and when it comes
the local drainage-way discharges in a few hours more water than is yielded
to it by the ordinary precipitation of many years. The deluge scours out
a channel which is far too deep and l)road for ordinary needs and which
centuries may not suffice to efface. The al)undance of these trenches, in
various stages of obliteration, but all manifestly nnsuited to the every-day
conditions of the country, has naturally led many to believe that an age of
excessive rainfall has but just ceased — an opinion not rarely advanced by
travelers in other arid regions. So far as may be judged from the size of
the channels draining small catchment basins, the rare, brief, paroxysmal
precipitation of the desert is at least equal while it lasts to the rainfall of the
fertile plain.
A line of cottonwoods marks the course of each living stream, but
otherwise the lowlands are treeless. So are most of the alluvial foot-slopes
and some of the smaller mountains, especially at the south. Except on the
high plateaus in central Utah, there is little that may be called forest. The
greater mountains have much timber in their recesses, but are not clothed
with trees. The growth is so irregular and interrupted that the idea of a
tree limit could not have originated here, but it may be said tli:it only tlie
straggling l)ush-like cedar passes below 6,000 feet at the noi'th or 7,000 feet
at the south. Only conifers are of such size and abundance as to have
economic importance. Oak and maple grow commonly as bushes, forming-
low thickets, but occasionally rank as small trees, along with the rarer box-
elder, ash, locust, and hackberry. The characteristic covering of the low-
lands is a sparse growth of low bushes, between which the earth is bare,
excepting scattered tufts of grass. Toward the north, and especially on the
higher plains, the grass is naturally more abundant and the bushes occupy
less space, but the introduction of domestic herds favors the ascendency of
the bushes. At the south the bushes are partly of different species, and they
are partially replaced by cactuses and other thorny plants. The })layas are
10 LAKE BONNEVILLE.
bare of all vegetation and are usually luai'giued by a gi-owtli of salt-loving
shrubs and grasses. A single southern bush bears leaves of deep green, but
with this exception the desert plants are grey, like the desert soil. These,
and the persistent haze whose grey veil deadens all the landscape, weary
the eye with their monotony, so that the vivid green marking the distant
spring is welcome for its own sake as well as for the promise of refreshment
to the thirsty traveler.
-The causes of this arid climate lie in the general cii'culntion of the
atmosphere, in the currents of the Pacific Ocean, and in tlie contiguration
of the land. There is a slow aerial di-ift from west to east, so that the air
coming to the Basin has previously traversed a portion of the Pacific, to
which its temperature and humidity have become iidjusted. Off the west
coast of the United States there is a southward current, believed to be the
chief branch of the Kuro Siwa. Prof. George Davidson' estimates its width
at about 300 miles, and finds that its temperature rises with southward
advance only one degree Fahrenheit for each degree of latitude. Being
derived from a north-moving current, it reaches our coast with a tempera-
ture higher than that normal to the latitude, while at the south its tempera-
ture is below the normal. As pointed out by Button,^ the air passing from
it to the land at the north is cooled by the land and precijiitates moisture,
while the similar air-current at the south is warmed by the land and con-
verted to a drying wind. The Great Basin fulls within the influence of the
drying wind, its southern ])nrt being more affected than its northern. At the
extreme south and the extreme north the moinitains between the ocean and
the Basin do not greatly interfere with the eastward flow of air, but between
latitudes 35° and 41° the Sierra Nevada forms a continuous wall, rarely less
than ten thousand feet high. In rising to pass this obstriu-tion the air loses
much of its stored moisture, especially in winter, and it descends to the Basin
with diminished humidity. The Basin is further influenced by deviations of
the air-currents from the eastward direction, and its southern ])art falls in
summer within the zone of calms theoretically due to a descending current
at the margin of the northern trade-wind; l)ut observational data are too
meager for the discussion of these factors.
1 Letter to the writer.
'Cause of the Arid Climate of the western portion of the U. S., C.apt. C. E. Diitton : Am. Jonr.
Sci., 3(1 sor., vol. 2», p. 2-19.
OTHER INTERIOR BASINS. , 11
The soutliem portions of Arizouu and New Mexico and the western part
of Texas resemble the Great Basin in climate, and they contain a number
of small interior basins. These are not so fully determined in extent as the
Great Basin, but several of tlit^ni ma}- be approximately indicated. One of
the largest lies between the Rio Grande and its eastern branch, the Pecos,
extending- from latitude 35° in central New Mexico to latitude 31° in west-
ern Texas. In its broadest part it is bounded on the west by the San An-
dreas and Orgaii Mountains, and on the east by the Sacramento and Guada-
loupe. Its area, of which two-thirds lies in New Mexico, is about 12,600
square miles. Southwest of the Rio Grande, in Mexico, there is a lai-ger
tract of interior drainage, containing a number of saline lakes, and to one
of these. Lake Guzman, the valley of the Mimbres River of New Mexico
descends. Other basins adjacent on either side to that of the Mimbres are
believed to bear the same relati( m to Lake Guzman, sloping gently toward
it, but contributing no Avater unless during periods of rare and exceptional
storm. Yet other basins without exterior drainage are contiguous to these,
and unite to form in soutluA'cstern New Mexico an arm of the Mexican
district of interior drainage, the area within New Mexico probably falling
between 7,000 and 7,500 square miles. North of this, and intersected cen-
trally by the 103d meridian and the 34th parallel, lies a smaller basin, includ-
ing the plain of San Augustin. Its area is about 1,800 square miles. In
southeastern Arizona a slightly smaller basin lies between the Caliyuro and
Dragoon Mountains on the west and the Pinaleflo and Chiricahua Mount-
ains on the east, including the Playa de los Pimas. Another and still smaller
basin is known to exist in tlie Hualapi Valley of northwestern Arizona, anc
it is probable that others occur in the western part of the Territory, both
north and south of the Gila River. When all have been deteriuined and
measured, it is estimated that the total area of the interior basins of the United
States, additional to the Great Basin, will be found equal to 25,000 square
miles, making the grand total for the United States about 232,000 square
miles — the thirteenth part of our territory. Mexico contains other inland
districts besides the one mentioned above, and the total area in that country
may be one-third as great as ours. It is probable that the remainder of the
continent di-ains to the ocean.
12 LAKE BONNEVILLE.
Large as are these districts, it is nevertheless true that North America,
as compared Avith otlier continents, is not characterized by interior (h-ainage.
According to data compiled by Murra}-, the closed basins in Australia aggre-
gate 52 per cent of its area, those of Africa 31 per cent, of Eurasia 28 per
cent, of South America 7.2 percent, of North America 3.2 per cent.' The
Great Basin is great oidv in comparison with siiuil;n- districts of our own
continent. The interior district of the Argentine Repul)lic and Bolivia is
half as larffe asrain, and thiit of central Australia exceeds the Great Basin
seven times; Sahara exceeds it sixteen tunes, and the interior district of Asia
twenty-three times.
HISTORY OF INVESTIGATION.
The history of the early geographic exploration of the Great Basin has
been carefully detailed by Simpson in the introduction to the report of his
own expedition. In 177C it was penetrated by Padi'e Escalante from the
southeast, and about the same time its southern rim was crossed by Path'e
Graces, but it does not appear that they discoA-ered the peculiarity of its
di-ainage. From about 1820 to 1835 the northern and l)roader portion of
the basin was gradually explored by Indian-traders, who learned of the
existence of undi-ained lakes and passed the account from mouth to mouth,
but made no maps and published no accounts of their discoveries. Cajit.
Bonneville, an army officer on leave, traveling in the interest of the fur
trade but with the spirit of exploration, took notes of geographic value
(1833), which were put in shape and published after a lapse of some years
by Washington Irving, and his map is probably the first Avhich represents
interior drainage. While Irving's account was in press, Fremont was en-
gaged in his justly celelmited exploration which afforded to t\\v world the
first clear conception of the hydrography of the region." Since that time
numerous cxjjeditions, public and private, have contributed details, so that
now the external boundary of the Great Basin is well known except at the
extreme south, and its internal configuration has been described and mapped
throughout four-fifths of its extent.
' The total annual rainfall of the laiiil of the globe, and the relation of rainfall to the annnal dis-
charge of rivers. By John Mnrr.ay. Scottish Geog. Mag. vol H, pp. (i.VTT.
-Report of the Exploring Expedition to the Rocky Mountains in the year 1H42 and to Oregon and
North California in the years lS4;i-'44. by Brovot-Capt. J. C. Fremont. Washington, 1S45.
STANSBURY ON ANCIENT SHORES. 13
Our knowledge of that lacustrine history to which the present volume
is a contribution begins ^^•ith 8tansbury. Fremont, finding a line of drift-
wood a few feet above the water of Great Salt Lake, inferred a small varia-
tion of its level, but appears to have overlooked the ancient shore-lines ter-
racing the mountains round about. lie described the coating of tufa on the
valley sides near Pyramid Lake, and the thought that it might be a lacust-
rine deposit occurred to liini, but was deemed inadmissible on account of the
thickness of the formation.
Stansbury in 1849 and 1850 made an elaborate survey of Great Salt
Lake and its vicinity, meandering its shore, determining its depth by a series
of soundings, and controlling his work by a system of triangulation. Li
his itinerary, while describing the plain Avliere now stands Lakeside station
of the Central Pacific railway, he says:
Tbis extensive flat api)ears to liave formed, at one time, the nortliern portion of
the lake, for it is now but slightly above its present level. Upon the slope of a ridge
connected with this plain, thirteen distinct successive benches, or water-marks, were
counted, which had evidently, at one time, been washed bj the lake, and must have
been the result of its action continued for some time at each level. The highest of
these is now about two hundred feet above the valley, which has itself been left by
the lake, owing probably to gradual elevation occasioned by subterraneous causes. If
this supposition be correct, and all api)earances conspire to support it, there must have
been here at some former period a vast inland sea, extending for hundreds of miles;
and the isolated mountains which now tower from the flats, forming its western and
southwestern shores, were doubtless huge islands similar to those which now rise
from the diminished waters of the lake.'
One of his sketches of Fremont Island, reproduced in a lithograph
facing page 102 of his report, exhibits terraces of the same sort, and he says
in another place that the island, which is "at least 800 or 900 feet high,"
presented "the appearance of regular beaches, bounded by what seemed
to have been well-defined and perfectly horizontal water-lines, at ditferent
heights above each other, as if the water had settled at intervals to a lower
level, leaving the marks of its former elevation distinctly traced upon the
hillside. This continued nearly to the summit, and was most apparent on
the northeastern side of the island."^
'Exploration and Survey of the Valley of the Great Salt Lake of Utah, .... by Howard Stans-
bury, Capt. Top. Eng., Philadelphia, 1852, p. 105.
?Ibid. p. 160.
14 LAKE BONNEVILLE.
Beckwith, who led a geographic expedition across the Great Basin in
1854, makes the next advance in the description of tlie hicustrine phenom-
ena, and liis contribution is so important that I quote it (entire:
Tlie olil .shore lines existing in the vicinity of tlie Great Salt Lake present an
interesting study. Some of them are elevated but a few feet (from five to twenty)
above the present level of the lake, and are as distinct and as well defined and pre-
served as its present beaches; and Stansbury speaks, in the Report of his exploration,
pages 158-160, of driftwood still existing upon those having an elevation of live feet
above the lake, which unmistakably indicates the remarkably recent recession of the
waters which formed them, whilst their magnitude and smoothly-worn forms as unmis-
takably indicate the levels which the waters maintained, at their respective forma-
tions, for very considerable periods.
Ill the Tuilla Valley, at the south end of the lake, they are so remarkably distinct
and peculiar in form and position that one of them, on which we traveled in crossing
that valley on the 7th of May, attracted the observation of the least informed team-
sters of our party — to whom it appeared artificial. Its elevation we judged to be twenty
feet above the present level of the lake. It is also twelve or fifteen feet above the
plain to the south of it, and is several miles long; but it is narrow, only affording a
tine roadway, and is crescent-formed, and terminates to the west as though it had once
formed a cape, projecting into the lake from the mountains on the east — in miniature,
perhaps, not unlike the strip of laud dividing the sea of Azoff from the Putrid sea.
From this beach the Tuilla Valley ascends gradually towards the south, and in a few
miles becomes partly blocked up by a cross-range of mountains, with passages at either
end, however, leading over quite as remarkable beaches into what is known, to the
Mormons, as Rush Valley, in which there are still small lakes or ponds, once, doubt-
less, forming part of the Great Salt Lake.
The recessions of the waters of the lake from the beaches at these comparatively
slight elevations, took place, beyond all doubt, within a very modern geological period;
and the volume of the water of the lake at each subsidence — by whatever cause pro-
duced, and whether by gradual or spasmodic action — seems as plainly to have been
diminished; for its present volume is not sufficient to form a lake of even two or three
feet in depth, over the area indicated by these shores, and, if existing, would be annu-
ally dried up during the summer.
These banks — wiiich so clearly seem to have been formed and left dry within a
period so recent that it would seem impossible for the waters which formed them to
have escaped into the sea, either by great convulsions, opening passages for them, or
bj' the gradual breaking of the distant shore (rim of the Basin) and draining them ofi",
without having left abundant records of the escaping waters, as legible at least as the
old shores they formed — are not i)eculiar to the vicinity of this lake of the Basin,
but were observed near the lakes in Franklin Valley, and will probably be found
near other lakes, and in the numerous small basins which, united, form the Great
Basin.
But high above these diminutive banks of rei-cnt date, on the mountains to the
east, south and west, and on the islands of the (iieat Salt Lake, formations are seen,
preserving, apparently, a uniform elevation as far as the eye can extend — formations
BECK WITH ON ANCIENT SHORES. 15
on a magnificent scale, wliicli, hastily examined, seem no less unmistakably tlian tbe
former to indicate tbeir sUore origin. Tliey are elevated from two or three hundred to
six or eight hundred feet above the i)resent lake; and if upon a thorough examination
they prove to be ancient shores, I hey will perhaps afford (lieing easily traced on the
numerous mountains of the Basin) the means of determining the character of the sea
by which tbey were formed, whether an internal one, subsequently drained off by the
breaking or wearing away of the rim of the Basin — of the existence of wliicli at any
time, in the form of continuous elevated mountain chains, there seems at prestiit but
little ground for believing — or an arm of the main sea, which, with the continent, has
been elevated to its present position, and drained by the successive stages indicated
by these shores.'
A year earlier Blake explored the Colorado desert between San Diego
and Fort Yiima, finding unmistakable evidence of its former occupation by
a lake. He observed a shore line, tufa dejiosits, and lacustrine clays, and
in the clays and tufa, as well as scattered over the sitrface of the desert, he
found fresh-water shells, and a single brackish shell, Gnathodoii. His de-
scription and disctission are full and eminently satisfactory, Init his expla-
nation takes the lake he describes out of the field of present interest, for he
shows that only its disappearance and not its origin is ■ to be ascribed to
climate. The lake basin was created by the growth of the delta of the Col-
orado River, which was built across the Gulf of California, separating a
portion of its upper end. When the river, shifting on its delta, is turned to
the right, a lake is maintained behind the barrier, a lake with outlet to the
Gulf, and therefore fresh. When the river turns to the left, it flows directly
to the Gulf, and the lake is dried away. The latter is the present and his-
toric condition, but occasionally at extreme flood a portion of the river's
water has been known to flow for many miles toward the desiccated basiu.^
Simpson, exploring for wagon routes in the broadest part of the Great
Basin, in 1859,^ observed in Cedar and Rush valleys the same water lines
that had been seen by Stansbury farther north; and Henry Engelniann,
the geologist of his party, noted not only shore terraces but lacustrine silt
and tufa and fresh-water shells. He points out that the saltness of the
'Explorations . . . from the month of the Kansas River, Mo., to the Sevier Lake, in the Great
Basin. By Lieut. E. G. Becliwith. Foot note to p. 97. In Pacifip, Railroatl reports, vol. 2, Washing-
ton, 185.5.
» Geological Report, by William P. Blake. In Pacific Railway Reports, vol. 5, 18.56, pp. 97-99,
236-239.
'Explorations across the Great Basin of the Territory of Utah for a direct wagon-route from
Camp Floyd to Genoa, in Carson Valley, in 1859, by Captain J. H. Simpson. Washington, 1876.
16 LAKE BONNEA^LLE.
Basin lakes is inconsistent witli the prevalent impression that they ])Ossess
subterranean outlets, and comparing their former with their present extent,
refers the difference to climate. lie arj^ues that tlu; ])reseut geographic con-
ditions tend to the diminution of rainfall, and that under them the basin has
become progressively more and more arid. But there is nothing in his dis-
cussion serving to explain the greater humidity of the preceding age.
The reports of Simpson and Engelmann, though prepared in manu-
script immediately after the completion of their exploration, were not printed
until 1S78, and in the mean time many observers saw the lake vestiges ami
wrote u})on them. Whitney, visiting Mono Lake in lS(i3, and noticing old
shore-lines rising in a series to the height of (JOG feet above the water, raised
the question — for many years unanswered — whether the old lake was con-
fined to the j\Iono Valley or communicated with lakes in other valleys of the
Great Basin, and pointed out that whatever conditions produced the ancient
glaciers of the adjacent Sierra were competent to expand the lake.^ If<»y-
den in 1870 examined the old shore-lines in the immediate \ncinity of Great
Salt Lake, coiTCctly correlated them with lacustrine deposits at various
points, sliowed their recency as compared to the later Tertiary beds of the
vicinity, and referred them to the Quaternary. He also found shells in the
de])osits, and from their character recognized the freshness of the old lake.^
Bradley, two years later, recognized the broad terraces flanking (^gden
River and other streams of the vicinity as deltas built by the same streams
in the ancient lake, observed that the Ogden delta deposits extended into
the mountain canyon of the river, and drcAv the important conclusion that
before the age of the high terraces Great Salt Lake was not far, if at all,
above its present level.' About the same time Poole made additional oljscr-
vations on the shore-lines of the same basin and tracud thnn as far westward
as the Deep Creek Mountains.*
The observations of Hay den, Bradley, and Poole were independent
and original, and by reason of priority of publication they belong to the
'Geol. Surv. of California, Geology, vol. 1, l)y J. D. Wbituey. Pliilailclpliia ISfi'i, pi>. 4ril-J,'i2.
2U. S. Geol. Surv. of Wyomiuj,'. . . 1870, by F. V. Hayilen. Wa.sliiut;ti)ii, 187'2, pp. 161), 170,
172, 175.
^ Report- of Frauk H. Bradley, in U. S. Geol. Surv. of the Territories, Ropt. for 1S72. Washing-
ton, 187:!, pp. 192, 11)6.
■•The Great American Desert, by Henry S. Poolo ; Proc. Nova Scotia Inst. Nat. Sci., vol. 3, pp.
208-220.
WHITNEY, KING, HAYDEN. 17
history of the subject, but, as ah-ead}- mentioned, they were partially an-
ticipated by those of Simpson and Engelmann, and wholly anticipated by
those of King, Hague and Emmons, the geologists of the Fortieth Parallel
Exploration. The work of tliis corps covered a belt one hundred miles
broad, spanning the Great Basin in its broadest part, and within this belt
the Pleistocene lakes were studied and for the first time approximately
mapped. It was shown that the corrugated surface of the Great Basin in
this latitude is higher in the middle than at the east and west margins, war-
ranting a general subdivision into the Utah Basin, the Nevada Plateau and
the Nevada Basin; that the Utah Basin formerly contained a large lake,
Bonneville, extending b(jtli north and south beyond the belt of survey; that
the Nevada Basin contained a similar lake, Lahontan, likewise exceed-
ing the limits of the belt; and that the valleys of the central plateau held
within the belt no less than eight small Pleistocene lakes. The mechanical
sediments and chemical deposits of the lakes were studied, and were ascer-
tained to overlie subaerial gravels, thus proving that a dry climate had pre-
ceded the humid climate of the lake epoch; and it was inferred from the
chemical deposits of Lake Lahontan that the lake had been twice formed
and twice dried away.^
The field work that afforded this important body of information was
performed chiefly in the years 1867-70, but publication was delayed till
1877-78. In 1872 Howell and the writer, traveling Avith topographic par-
ties of the Wheeler Survey, traversed the Utah Basin on many lines, and
our reports, printed in 1874 and 1875, contained an account of Lake Bon-
neville, the extent of Avhicli we were able to indicate with inconsiderable
error, and to which the writer gave a name.^ Thus, by an accident of pub-
lication. King and his colleagues lost that literary priority in regard to Lake
Bonneville to which they were fairly entitled by priority of investigation.
'Geol. Expl. of the 40th Parallel. Vol. 1, Systematic Geology, by Clarence King. Washington,
1878; vol. 2, Descriptive Geology, by Arnold Hague and S. F. Emmons. Wasliington, 1877.
* Prelim. Geol. Rept. by G. K. Gilbert; Appendix D to Progress Rept. Expl. and Sur. W. of
the 100th Mer. in 1872. Washington, 1874, pp. 49-50.
Explorations* and Surveys west of the 100th Meridian, vol. 3, Geology. Washington, 1H75. Part
1, by G. K. Gilbert, treats of Lake Bonneville on pp. 88-104. Part 3, by Edwin E. Howell, treats of
Lake Bonneville on pp. 249-251.
MON I 2
18 LAKE BONNEVILLE.
In 1877 Pealc observed shore terraces in various parts of (Jaolie valley.'
From 1875 to 1878 I spent each summer in Utah as a mem1)er of the
Powell survey, and found many ()i)it(trtunities in connection with other work
to continue the study of Lake Bonue\'ille. This \vas especiall}' the case in
1877, when the duty of gathering inforaialion as to the irrigable land of the
basin of Great Salt Lake led me all about the margin of the Salt Lake desert.
When the corps for western surveys were reorganized in 1879, 1 was placed
in charge of the Division of the Great Basin, with tlie understanding that the
Pleistocene lakes, previously investigated only in an incidental way, should
fonn a principal subject of study. Late in the season some months were
spent in the field, with Mr. W. D. Johnson as assistant; and a corps was
oi'ganized the following year. Of this coi'ps, Mr. Israel C. Russell was \)vin-
cipal assistant, and he remained with the work from first to last, l^eing
assigned independent investigations after the first season, ilessrs. H. A.
Wheeler, W. J. McGee, and Geo. M. Wright took pai-t in the geologic work
for shorter periods. Messrs. Gilbert Thompson, Alljcrt L. Webster, Willard
D. Johnson, and Eugene Ricksecker, associated with the work at various
times as topographers, and Messrs. Fred. D. Owen, J. B. Bernadou, and E.
R. Trowbridg-e, temporarily attached to field jjarties as general assistants,
all contril^uted to the mapping and illustration of the lake jjhenomena.
The field work of the year 1880 was in the Bonneville Basin, and little
was afterAvard done in that area. In 1881 Mr. Russell made a ])relinnnary
e.\annnation of the vestiges of Lake Lahoiitau in the Nevada IJasin and of
the Mono Basin, aiid in the following spring extended his reconnaissance
to the lake basins of southeastern Oregon. I was called to Washington in
the spring of 1881 on duty supposed to be temporai-y, but remained there
until the following year, w hen the work of the Surve}, pre\iously restricted
to the western l\'rritories, was extended l)y C<->ngress to the eastern States
also. As the enlargement of field and function was not accompanied l)yan
equivalent increase of funds, it became necessary to curtail the western
work of the Survey, and it was decided to stop the investigation of the
Pleistocene lakes as soon as this could lie done witliout •'•reat sacrifice of
' Keport, of A. C. Peale, in U. S. GeqJ. Surv. of tho Territories for 1877, Washiugtou, 1879, pp.
603-606.
U S. GEOLOGICAL SURVKY
LAKE BONNE^/ILLE PL m
113°
112°
111°
42«^
41'
39"
38'
MAP OF
'L/\KE BONNEMLLE
showing
ROUTES OF THA\^EL
Routes by G. K-Gilbert ^^ "*
JVdditional routes by Assistants
Julius Bien A Iji.lith
Drown by C TfaompBon
RUSSELL, DANA, GALL. 19
material already acquired. Mr. Russell completed the study of the Lalion-
tau and Mono Basins by the close of the season of 1883 and then returned
east. I made a single excursion in the summer of 1883, devoting a few
weeks to supplementary observations in the Bonneville, Lahontan, and Mono
Basins, and visiting Owens Valley to examine the geologic features of the
Inyo earthquake. The examination of the more southerly valleys of the
Great Basin, the study of the brines and saline deposits, and the elaborate
measurement of post-Pleistocene displacements, are indefinitely deferred.
The results of the investigation have been communicated in a series of
reports, essays, and memoirs. An outline of the Bonneville history was
published by me in 1882,' and an essay on shore topography in 1885.^
Russell's results have appeared in a preliminary report on Lake Lahontan,^
reports on the Oregon basins'* and the Mono Basin, ^ and a monograph on
Lake Lahontan.^ An essay on the Pleistocene fresh-water shells ^vas pre-
pared and published by Call,' and one on the pseudomorph thinolite by
Dana.* The present publication completes the series.
'Coutributions to the history of Lake Bonneville: Second Ann. Kept. U. S. Geol. Survey. Wash-
ington, 1882, pp. 169-200.
= The topographic features of lake shores: Fifth Ann. Kept. U. S. Geol. Survey. Washington,
1885, pp. 7.5-123.
Adiscnssion of post-Bonneville displacement appeared in an address "The luculcation of Scien-
tific Method by Example," read to the American Society of Naturalists Dec. 27, 1885, and printed
in the Am. Jour. Sci., vol. 31, pp. 284-291). A description of the jointed structure of the Bonneville
beds was printed in the Am. Jour. Sci., 3d Series, Vol. 23, 1882, pp. 25-27.
'Sketch of the Geological History of Lake Lahontan : Third Ann. Kept. U. S. Geol. Survey. Wash-
ington, 1883, pp. 189-235.
^A geological reconnaissance in Southern Oregon: Fourth Ann. Rept. U. S. Geol. Survey. Wash-
ington, 1885, pp. 431-164.
•'* Quaternary history of Mono Valley, California : Eighth Ann. Rept. U. S. Geol. Survey. Washing-
ton, 1880, pp. 261-394.
15 Geological History of Lake Lahontan : Mon. U. S. Geol. Survey, No 11, Washington, 1885, pp. 302.
Other publications by Mr. Kussell containing portions of the same material are —
Lakes of the Great Basin: Science, vol. 3, 1884, pp 322-323.
Dejiosits of Volcanic Dust in the Great Basin : Bull. Phil. Soc, Washington, vol. 7, 1885, pp. 18-20.
Notes on the Faults of the Great Basin, . . . : Bull. Phil. Soc. Washington, vol. 9, 1887, pp. 5-8.
The Great Basin. In Overland Monthly, 2d Series, vol. 11, 1888, pp. 420-426.
'On the Quaternary and Recent MoUnscaof the Great Basin, with descriptions of new forms. By
E. Ellsworth Call. Introduced by a Sketch of the Quaternary Lakes of the Great Basin, by G. K.
Gilbert. Bull. U. S. Geol. Survey No. 11, 1884, 56 pp.
"A Crystallographic Study of the Thinolite of Lake Lahontan. By Edward S. Dana. Bull. U. S.
Geol. Survey No. 12, 1884. 29 pp.
20 LAKE BONNEVILLE.
THE BONNEVILLE BASIN.
The Great Basin comprises a large number of sul^sidiary closed basins,
each draining to a lake or ])laya. Aliout sixty ot" these could be enuiiicnited
from present knoAvledge, and the fvdl nuiiil)er may be as high as one luni-
dred. In the last geologic epoch a more humid climate (■(inverted iii;iiiy,
or perhaps all, of these playas into lakes, and enlarged all the lakes. Some
lakes overflowed the rims of their basins, becoming tributary to others; and
the lakes of adjacent basins in many instances expanded until they l)ecaine
continent. A few of the overflowing lakes discharged across the rim of the
Great Basin, thus becoming tributary to the ocean, and subtracting their
catchment basins from the district of interior drainage. In the remaining
portion of the district the nmnber of independent drainage areas A\'as reduced
by coalescence.
The laro-est of the confluent lakes Avere formed at the eastern and
western raai-gins of the Great Basin, being separated by the plateau of
eastern Nevada. Lake Lahontan at the west was fed chiellA- In' the snows
of the Sierra Nevada, Lake Bonneville at the east by those of the Wasatch
and Uinta mountains.
The catchment basin of Lake Bonneville comprises that part of the
Great Basin lying east of the Gosiute, Snake, and Piiion mountains of east-
ern Nevada — an oblong ai-ea embracing about five degrees of latitude and
three of longitude, and containing about 54,000 squai-e miles, or the fourth
part of the area of the Great Basin. Its western two-thirds may be described
as a plain ranging in altitude from 4,200 to 5,500 feet above tide, and more
or less interrupted by short moiuitain ranges trending north and south. At
the north, where the mountains are comparatively few and small, the barren
plain is called the Great Salt Lake Desert, and similar open stretches at the
south are named the Sevier Desert and the Escalante Desert. The eastern
third is much higher, including the lofty Wasatch Range and its dependen-
cies, the western end of the still loftier Uinta Range, and the western jjart
of the district of the High Plateaus. Several peaks of the Wasatch and
Uinta Mountains rise above the level of lL*,000 feet, and the High Plateaus
culminate near Beaver in the Tusliar ridge with peaks of similar altitude.
THE BONNEVILLE BASIN. 2l
The eastern uplands are the only important condensers of moisture,
and from them flow a sj'stem of rivers whose Avaters are eva])orated in the
salt lakes of the lowlands. The Bear, the Weber, and the Provo-Jordan
have their principal sources in the Uinta Mountains, and break through the
Wasatch Range on their way to Great Salt Lake. One of the upper val-
leys traversed by the Bear River contains Bear Lake, a body of fresh water;
and Utah Lake, likewise fresh, receives the Provo and discharges the Jor-
dan. The Sevier River, after flowing 1,50 miles nortlnvard among the
plateaus, receives the San Pete from the nortli and then turns westward
to Sevier Lake, the saline of the Sevier Desert.
The eastern uplands are better timbered than any other part of the Great
Basin. The upland valleys are fertile, but having a climate too cool for
agriculture are devoted to grazing and maintain only a scant population.
The western plain is infertile by reason of aridity, and is almost without
inhabitants. The lower valleys of the rivers, where they issue from the
uplands upon the plain, have a climate suited for agriculture, are rendered
fertile by irrigation, and constitute a habitable zone, over which the Mor-
mon community has spread.
To understand fully the topographic relations described above, the
reader should examine the large map of Lake Bonneville (in a pocket
attached to the cover of this volume), where the reliefs are expressed by
contour lines at each 1,000 feet; and also Plate XII, whereon are marked
the boundary of the Bonneville Basin and tlie boundaries of the equivalent
group of smaller basins as they exist at the present time. He will find also
that the plate supplements the expression of the distribution of the uplands,
by contrasting the area above 7,000 feet with the area below; and he can
learn from it more readily than through words the relation of the basin to
the political diA-isions of the country. By turning again to Plate II he will
see that the Bonneville basin adjoins interior drainage only on the west;
its northern rim parts it from the basin of Snake River, a branch of the
Columbia, its eastern and southern from the basin of the Colorado of the
West. The more important streams heading near the northern rim and
flowing to the Snake are the Salt, Blackfoot, Portneuf, Bannack, and Raft.
In the eastern rim rise Black's Fork, the Uinta, and the Price, all tributary
22 LAKE BONNEVILLE.
to the Green before it joins the Colorado, tind the San Rafael, Fremont, and
Escalante, immediate tributaries of the Colorado. The Paria, Kanab, and
Virffen flow to the Colorado from the southern rim.
CHRONOLOGIC NOMENCLATURE.
The geologic period to which the Bonneville history has been referred
has three names in good standing, Quaternary, Pleistocene, and Glacial.
Each name varies more or less in scope as used by different authors, but as
ordinarily understood the three are strictly synonymous. In earlier Avrit-
ings I have preferred Quaternary, in the present I prefer Pleistocene.
No vital principle is involved in either preference, and indeed I am not
of those who clamor for the rights of words. In my judgment words have
no rights which the users of words are bound to respect. The claim of a
word for preference rests only on its utility — its convenience for the com-
munication of thought.
Glacial connotes glaciers, and was a convenient name while it was sup-
posed that a cold climate marked the whole period. But now that interrup-
tions of that climate are recognized, it is more convenient to speak of glacial
epochs and interglacial epochs of the Quaternary or Pleistocene })eriod.
Quaternary connotes a fouribld classification, and is coordinate \vith
Tertiary. Pleistocene suggests by its termination coordination with the
subdivisions of the Tertiary. Using the scale of time-nouns adopted by the
International Congress of Geologists, the Quaternary is an era, having the
classificatory rank of the Tertiary era, and the Pleistocene is a period, rank-
ing with the Eocene period. It is generally believed that the Pleistocene is
comparable in ])oint of diiration with one of the periods of the Tertiar}* era,
being less rather than greater, and those who advocate the emplopnent of
the name Quaternary recognize the Quaternary era as one containing but a
single period. The time division with which we have to deal is, then, from
eveiy point of view, a "period," and it is believed that the use of the name
Pleistocene Period involves a minimum amount of implication as to higher
classification, a subject whose discussion is not here contemplated.
CHAPTER II.
THE TOPOGRAPHIC FEATURES OF LAKE SHORES.
It has been assumed in the i)veceding- pag-es that valleys trom which
lakes have recently disappeared are characterized l)y certain features
wherebv that lact can he recognized. Perhaps no one observant of natural
phenomena will disjjute this. But there is, nevertheless, some diversity of
opinion as to what are the peculiar characters to which lakes give rise; and
especially has the true interpretation of certain local topographic features
been mooted, some geologists ascribing them to waves, and others to dif-
ferent agencies.
In the investigation of our ancient lake, it has been found necessary
not only to discriminate from all other topographic elements the features
created by its waves, but also to ascertain the manner in which each was
produced, so as to be able to give it the proper interpretation in the recon-
struction of the history of the lake. It is proposed in this chapter to pre-
sent the more general results of this study, describing in detail the various
elements which constitute shore topography, explaining their origin, so far
as possible, and finally contrasting them with topographic features of other
origin which so far simulate them as to occasion confusion.
The play of meteoric ag-ents on the surface of the land is unremitting,
so that there is a constant tendency to the production of the forms charac-
teristic of their action. All other forms are of the nature of exceptions,
and attract the attention of the observer as requiring explanation. The
shapes wrought by atmospheric erosion are simple and symmetric and need
but to be enumerated to be recognized as normal elements of the sculpture
23
24 LAKE BONNEVILLE.
of the land. Along each di-aiuage line there is a gradual and gradually
increasing ascent from mouth to source; and this law of increasing acclivity
applies to all branches as well as to the mnin stem. Between each ))!iir of
adjacent drainage lines is a ridge or hill, standing midway and roundcMl at
the top. Wherever two ridges join there is a sunnnit higher than the adja-
cent portion of either ridge; and the highest summits of all arc those which,
measuring along lines of drainage, are most remote from the ocean. The
crests of the ridges are not horizontal but undulate from summit to summit.
There are no sharp contrasts of slope; the concave profiles of the drainage
lines change their inclination little by little and merge by a gradual transi-
tion in the convex profiles of the crests and sununits.
The factor Avhich most frequently, and in fact almost universally, inter-
rupts these simple curves is heterogeneity of terrane. Under the infiuence
of this factor, just as in the case of a homogeneous terrane, the declivities
adjust themselves in such way as to oppose a maxinmm resistance to erosion;
and with diversit}' of rock texture this adjustment involves diversity of form.
Hard rocks survive, while the soft ai"e eaten away. Peaks and clifts are
})ro<luced. The apices are often angular instead of roUnded. Profiles
exhil)it abrupt changes of slope. Flat-topped ridges appear, and the dis-
tribution of maximum sununits becomes in a measure independent of the
leno'th of drainao^e lines.
A second factor interrupting the continuity of erosion profiles is up-
heaval; and this produces its effects in two distinct ways. First, the general
uprising of a broad tract of land affects the relation of the drainage to its
point of discharge or to its base level, causing corrasion liy streams to be
more rapid than the general Avaste of the surface and producing i-anyons
and terraces. Second, a local uprising by means of a fault produces a clifi"
at the margin of the uplifted tract; and above this cliff there is sometimes
a terrace.
A third disturbing factor is glaciation, the cirques and moraines of
which are distinct from anything wrought liy pluA-ial erosion; ;nid a fourth
is found in eruption.
The products of all these agencies except the last have been occasionally
confused with the phenomena of shores. The beach-lines of Glen Roy have
SCULPTURE OF THE LAND. 25
been called river terraces and moraine terraces. The cliffs of the Downs of
Eno-land have been ascribed to shore waves. Grlacial moraines in New
Zealand have been interpreted as shore terraces. Beach ridges in t)ur own
conntry have been described as glacial moraines, and fault terraces as well
as river terraces have been mistaken for shore-marks.
In the planning of engineering works for the im})rov('iuent and protec-
tion of harbors, it is of })riine importance to understand the natural pntcesses
by which coast features are produced and modified, iuid this necessity has
led t( » the production by engineers of a large though widely scattered litera-
ture on coast-forming agencies. Geologists also require for the interpre-
tation of strata originating as coast deposits an understanding of the metliods
of coastal degradation and coastal deposition, and from their point t)f view
there has arisen an independent literature on the subject. The physical
theory of water waves required alike by engineers and geologists has been
developed by physicists, and has its own literature. The three groups of
writers have so thoroughly traversed the subject of shore })rocesses that the
present chapter would have need to demonstrate its raison d'etre were it not
that the general subject has as yet received no compendious and systematic
treatment in the English language.
It happens, moreover, that the present treatment of the subject has its
own peculiar point of view, and is in large part independent. During the
progress of the field investigation I was unaware of the greater part of the
literature mentioned above, having indeed met with but one important
pa})er, that in which Andrews describes the formation of beaches at the head
of Lake Michigan, and I was induced by the requirements of my work to
develop the philosophy of the subject ab initio. The theories here presented
had therefore received approximately their present form and arrangement
before they were compared with those of earlier writers. They are thus
original without being- novel, and their independence gives them confirma-
tory value so far as they agree with the conclusions of others.
The peculiarity of the point of view lies in the fact that the phenomena
chiefly studied are fossil shore-lines instead of modern. The bodies of water
to which they pertain having disappeared, the configuration of the sub-
merged portion is directly seen instead of being interpreted from laborious
26 LAKE BONNEVILLE.
soundiiifjs. There are, moreover, natural sections of the deposits, exposed
by subsequent erosion, and these reveal features of internal structure or
anatomy quite as important to the geologist as the features of morphology.
The literature of shore-lines is so feebl}- connected by cross reference, and
portions of it have been discovered in places .so unexpected, that the writer
fears many important c.ontril)utions have escaped his attention. Within the
range of his reading, the earliest discussions of value are by Beaumont^ and
De la Beche,'- and it must be admitted that the writers of gef)logic manuals
now in use have improved very little upon their presentation. Fleming, in
an essay on the origin and preservation of the harbor of Toronto,^ set forth
the process of littoral transportation witli admirable clearness; and Andrews,
who appears to have reached his conclusions by independent observation,
added to the theory of littoral transportation an important factor in the
theory of littoral deposition.'' Mitchell, in an essay on tidal marshes,'^ inci-
dentally describes the growth of the protecting barrier. A general treatise
by Cialdi" gives a systematic discussion of coast processes from the engi-
neer's point of view, and reviews the Italian literature of the subject; and
a shorter paper by Keller^ has a similar scope. Richthofen, in liis manual
of instruction to scientific travelers, treats analytically and at length of the
work of waves in conjunction with tides, and discusses a subsiding conti-
nent.* The theory of waves has been developed experimentally by a com-
mittee of the British Association, with J. Scott Russell as reporter;® and it
is analytically treated by Airy'" and Rankine."
' Legons de geologic pratiiiiie. Par Elie de Beaumont. Vol. 1, pp. 221-253, Paris, ISJ.^.
= A Geological Manual. By Henry T. De la Becbe. 3d edition, enlarged, London, 1833, pp. (17-91.
The Geological Observer. By tbe same. London, 18.'>1, pp. 49-117.
'Toronto Harbor — its fonnation and preservation. By Sandford Fleming, C. E. : Canadian
Journal, vol. 2, ls54, pp. 103-107, 223-230. Reprinted witb additions as Report on Preservation and
Improvement of Toronto Harbor. In Supplen^ent to Canadian Journal, 1854, pp. 15-29.
■"Tbe North American Lakes considered as cbronometers of post-Glacial time. By Dr. Edmund
Audrows. Trans Chicago Acad. Sci., Vol. 2, pp. 1-23.
i^On the reclamation of tide-lands and its relation to navigation. By Henry Mitchell. Appen-
dix No. 5, to Rept. U. S. Coast .Survey for l-^GO. Washington, 1872, pp. 75-104.
«Snl moto ondoso del mare e sn le correnti di esso specialmente sii (juello littorali. Alessandio
Cialdi, Rom.n, 18G6.
'Studien nberdie Gestaltung dcr Sandku.sten, etc., 11. Keller, Berlin, 18S1.
'Fiihrer fiir Forscbuugsrciscnde, vou Ferdinand Freiherr von Richthofen. Berlin, 1880, pp.
336-365.
9 Report of the Committee on Waves, by Sir John Robinson, and John Scott Russell, Reporter:
Rept. British Ass. Adv. Sci., 7th meeting, 1837, pp. 417-496.
'"G. B. Airy, Vol. V, Ency. Metrop.
"W. J. McQ. Rankine, Philos. Trans. Royal Soc. London, vol. 153, 1863, pp. 127-13-'.
LAND SHAPING AND SHORE MAKING. 27
In the following' treatment, of the subject the descri])tion and analysis
of the elements of shore topography will be followed by a comparison of
certain of these elements with sinuilating features of ditferent origin. First,
however, a few words will be devoted to the consideration of shore shaping
as a di\'ision of the more general process of earth shaping.
The earth owes its spheroidal form to gravity and rotation. It owes
its o-reat features of continent and ocean bed to the mieciual distribution of
the heterogeneous material of which it is composed. Many of its minor
inequalities can be referred to the same cause, but its details of siu'face are
chiefly molded by the circulation of the fluids which envelope it. This
shaping or molding of the surface may be divided into three parts — sul)-
aerial shaping (land sculpture), subaqueous shaping, and littoral shaping.
In each case the process is threefold, comprising erosion, transportation, and
deposition.
In subaerial or land shaping the agents of erosion are meteoric — rain,
acting both mechanically and chemically, streams, and frost. The agent of
transportation is running water. The condition of deposition is diminishing
velocity.
In subaqueous shaping, or the molding of surface which takes })lace
beneath lakes and oceans, currents constitute the agent of erosion. They
constitute also the agent of transportation; and the condition of deposition
is, as before, dimiiaishing velocity.
In littoral shapings or the modeling- of shore features, waves constitute
the agent of erosion. Transportation is performed by waves and cuiTents
acting conjointly, and the condition of deposition is increasing depth.
On the land the amount of erosion vastly exceeds the amount of dep-
osition. Under standing water erosion is either nil or incomj)arably inferior
in amoiint to deposition. And these two facts are correlatives, since the
product of land erosion is chiefly deposited in lakes and oceans, and the
sediments of lakes and oceans are derived chiefly from land erosion. The
products of littoral erosion undergo division, going partly to littoral dep-
osition and partly to subaqueous deposition. The material for littoral
deposition is derived partly from littoral erosion and partly from land
erosion.
28 LAKE BONNEVILLE.
That is to say, the detritus worn from the land by meteoric agents is
transported outward by streams. Normally it is all carried to the coast, but
owing to the almost universal complication of erosion with local uplift, there
is a certain share of detritus dep<isited upon the basins jind lower slopes of
the land. At the shore a second <li\isi()n takes place, the smaller portion
being arrested and l)uilt into various shore structures, while the larger por-
tion continues outwnrd and is deposited in tlic sen or lake. The product of
shore erosion is similarly divided. A part remains upon the slntre, wliere it
is combined wilh material derived from the hnid, and the remainder goes to
swell the volume of subac^ueous deposition.
The forms of the land are given chiefly by erosion. Since the wear
by streams keeps necessarily in advance of the waste of the intervening
surfaces, and since, also, there is inequality of erosion dependent on diver-
sity of texture, land forms are characterized by their variety.
The forms of sea beds and lake beds are given by deposition. The
great currents by which subaqueous sediments are distributed swee^) over
the ridges and other prominences of the surface and leave the intervening de-
pressions comparatively currentless. Deposition, depending on retardation
of current, takes place chiefly in the depressions, so that they are eventually
filled and a monotonous uniformity is the result.
The forms of the shore are intermediate in point of variety between
those of the land and those of the sea bed; and since they alone claim
parentage in waves, they are sui generis.
Ocean shores are genetically distinguished from lake .shores by the
cooperation of tides, which modify the work accomjilLshed by waves and
wind currents.
The phenomena of ocean shores are therefore more complicated than
those of lake shores, and an exhaustive treatment of the subject would
include the discussion of their distinjiuishino- characteristics, l^hev fall,
however, without the limits of the present investigation, and in the analysis
which follows, the influence of tides is not considered. It is perhaps to be
regretted that the systematic treatment here jiroposed could not be so
extended as to include all shores, but there; is a cei'tain compensation in the
fact that the results reached in reference to lake shores have an important
SEA SHORES AND LAKE SHORES. 29
neo-ative becaring on tidal discussions. It was long ago pointed out by
Beaumont^ and Desor^ that many of the more important features ascribed
by hydraulic engineers to tidal action, are produced on the shores of inland
seas liy waves alone; and the demonstration of wave work pure and simple
should be serviceable to the maritime engineer by pointing out those results
in explanation of which it is unnecessary to appeal to the agency of tides.
The order of treatment is based on the three-fold division of the proc-
ess of shore shaping. Littoral erosion and the origin of the sea-cliff and
wave-cut terrace will be first explained, then the process of littoral trans-
portation with its dependent features, the beach and the barrier, and finally
the process of littoral deposition, resulting in the embankment, with all its
varied phases, and the delta.
WAVE WORK.
LITTORAL EROSION.
In shore sculpture the agent of erosion is the wave. All varieties of
wave motion which aff'ect standing water are susceptible of producing ero-
sive eff"ect on the shore, but only those set in motion by wind need be con-
sidered here. They are of two kinds: the wind wave proper, which exists
only during the continuance of the wind; and the swell, which continues
after the wind has ceased. It is unnecessary to discriminate the effects of
these upon the shore further than to say that the wind wave is the more
efficient and therefore the better deserving of special consideration. In the
wind wave two things move forward, the undulation and the water. The
velocity of the undulation is relatively rapid; that of the water is slow and
rhythmic. A particle of water at or near the surface, as each undulation
passes, describes an orbit in a vertical })lane, but does not return to the
starting point. While on the crest of the wave it moves forward, and while
in the trough it moves less rapidly backward, so that there is a residual
advance.'
' Lefons ile gdologie pratique, vol. 1, p. 232.
"^ E. Uesor, Geology of Lake Superior Land District by Foster & Whitney, Washington, 1851,
vol. 2, pp. 2fi2, 266.
^The theory of wave motion involved in this and the following paragraphs is based partly on
observation but chiefly on the discussions of J. S. Russell, Airy, Cialdi, and Rankine.
30 LAKE BONNEVILLE.
This residual advance is the initiatory element of current. By virtue
of it the upper layer of water is carried forward with i-eference to the layer
below, being given a differential movement in the direction towards which
the wind blows. This movement is gi'adually propagated to lo^ver aqueous
strata, and ultimately produces movement of the whole body, or a wind-
wrought current. So long as the velocity of the wind remains constant, the
velocity of the current is less than that of the wind; and there is always a
differential movement of the water, each layer moving faster than the one
beneath. The friction is thus distril)uted through the whole vertical column,
and is even borne in part liy the lake bottom. The greater the depth the
smaller the share of friction a})portioiied to each layer of water and the
greater the velocity of current which can be communicated Ijy a given wind.*
The height of waves is likewise conditioned by depth of water, deep water
permitting the formation of those that are relatively large.
When the wave approaches a shelving shore its habit is changed. The
velocity of the undulation is diminished, while the velocity of the advancing
particles of Avater in the crest is increased; the wavelength, measured from
trough to trough, is diminished, and the wave height is increased; the crest
becomes acute, with the front steeper than the back; and these changes
culminate in the breaking of the crest, when the undulation proper ceases.
The return of the water thrown forward in the crest is accomplished by a
current along the bottom called the undertow. The momentum of the
advancing water contained in the wave crest gives to it its power of erosion.
The undertow is efficient in i-emoving the products of erosion.
The retardation of the undulation by diminishing de])t]i < if water I'lianges
the direction of its axis or crest line — excepting when the axis is parallel to
the contours of the shoaling bottom — and the phenomena are analogous to
those of the refraction of light and sound. As a, wave passes obliquely
from deej) water to a broad shoal of iniiform depth, the end first entering
shoal water is first retarded and the crest line is for the moment bent. When
the entire crest has reached shoal water it is once more straight, but with a
new trend, a trend making a narrower angle with the line of sejiaration
' This is a matter of observation rather than theory. It implies that the friction between con-
tiguous films of water increases iu more than simple ratio with the differential velocity of the films.
REFRACTION OF WIND WAVES. 31
between deep and shallow water. The wave has been i-efracted. When a
wave passes obliquely from deep water to shoal water whose bottom grad-
ually rises to a shore, the end nearer the shore is the more retarded at all
stages of progress and the crest line is continuously curved. When the
wave breaks and the inidulation ceases, the crest line is nearly parallel to
the shore. It results that for a wide range of wind direction there is but
small rauffe in the direction of wave trend at the shore. It results also, as
has been often noted, that Avhen the wind blows ncirmally into a circling
bay, the waves it brings are diversely turned, so as to beat against both
sides as well as the head of the bay.
When the land at the margin of the water consists of unconsolidated
material or of fragmental matter lightly cemented, the simple impact of the
water is sufficient to displace or erode it. The same force is competent also
to disintegrate and remove firmer rock that has been superficially weakened
by frost or is partially divided by cracks, but it may be doubted whether it
has any power to wear rock that is thoroughly coherent. The impact of
large waves has great force, and its statement in tons to the square foot is
most impressive; but, so far as our observation has extended, the erosive
action of waves of clear water beating upon firm rock without seams is prac-
tically nil. On the shores of Lake Bonneville, not only was there no erosion
on the faces of cliffs at points where the waves carried no detrital fragments,
but there was actually deposition of calcareous tufa; and this deposition was
most rapid at points specially exposed to the violence of the waves.
The case is very different when the rock is divided by seams, for then
the principle of the hydrostatic press finds ap])lication. Through the water
forced into the seams, and sometimes through air imprisoned and compressed
by the water, the blow stru(;k liy the wave is applied not merely to large
surfaces but in directions favorable to the reiidino- and dislocation of rock
masses.
It rarely happens, however, that the impact of waves is not reinforced
by the impact of mineral matter borne by them. The detritus worn from
the shore is always at hand to be used by the waves in continuance of the
attack; and to this is added other detritus carried along the shore by a pro-
cess presently to be described.
32 LAKE BONNEVILLE.
The rock frari^-ments which constitute the tool of erosion are themselves
worn and comminuted by use until they become so fine tliat they no longer
lie in the zone of breakers but are carried away by the undertow.
The direct work of wave erosion is restricted to a horizontal zone de-
pendent on tlie heiylit of the waves. There is no impact of breakers at levels
lower than i\w troughs of the waves; and the most efficient impact is limited
upward l)y the level of the wave crests, although the dashing of the water
produces feebler blows at higher levels. Tlie indirect work has no suj)erior
limit, for as the excavation of the zone is carried landward, masses higher
up on the slope are sapped so as to break away and fall b}' mere gravity.
Being thus brought within reach of the waves, they are then broken up by
them, retarding the zonal excavation for a time but eventually adding to the
tool of erosion in a way that partially compensates.
Let us now consider what goes on beneath the surface of the water.
Tlie agitation of which waves are the superficial manifestation is not re-
stricted to their horizon, but is propagated indefinitely downward. Near
the surface the amount of motion diminishes rapidly downward, but the rate
of diminution itself diminishes, and there seems no theoretic reason for as-
signing any limit to the propagation of the oscillation. Indeed, the agitation
must be carried to the bottom in all cases where the depth operates as a
condition in determining the magnitude of waves, for that determination
can be assigned only to a resistance opposed by the bottom to the undula-
tion of the water.
During the passage of a wave each particle of water affected by it rises
and falls, and moves forward and backward, describing an orbit. If the
passing wave is a swell, the orbit of the ])article is closed,^ and is either a
circle or an elli[)se; but in the case of a wind wave the orbit is not closed.
The relative amounts of horizontal and vertical motion depend on the depth
of the particle beneath the surface, and <in the relation of the total de})th of
the water to the size of the wave. If the water is deep as comj)ared to the
wave-length, the horizontal and vertical movements are sensibly equal, and
their amount diminishes rapidly from the surface downward. If the depth
'This is strictly true only while the swell tr.averses deep water. It is pointed out by Cialdi that
in passiiij; to shoal water the swell is converted into a wave of translation, and the particles no longer
return to their points of starting.
PULSATION OF THE UNDIilHTOW. 33
is small, the liorizontal motion is greater than the vertical, but diminishes
less rapidly with dei)tli. Near the line of breakers, the vertical motion close
to the bottom becomes inap})reciable, while the horizontal oscillation is
nearly as great as at the surface. This horizontal motion, affecting water
which is at the same time under the influence of the undertow, gives to that
current a pulsating character, and thus endows it with a higher transporting
power than would pertain to its mean velocity. Near the breaker line, the
oscillation communicated by the wave may even overcome and momentarily
reverse the movement of the undertow. Inside the breg-ker line no oscilla-
tion proper is communicated. The broken Avave crest, dashiilg forward,
overcomes the undertow and throws it back; but the water returns without
acceleration as a simple current descending a slo})e.
It should be explained that the increment given by pulsation to the
transporting power of the undei'tow depends upon the general law that the
transporting power of a current is an increasing geometric function of its
velocity. Doubling the velocity of a current more than doubles the amount
it can carry, and more than doubles the size of the particles it is able to
move.
The transporting power of the undertow diminishes rapidly from the
breaker line outward. That part of its power which depends on its mean
velocity diminishes as the prism of the undertow increases; that j)art which
depends on the rhythmic accelerations of velocity diminishes as the depth of
water increases.
The pulsating current of the undertow has an erosive as well as a
transporting function. It carries to and fro the detritus of the shore, and,
dragging it over the bottom, continues downward the erosion initiated by
the breakers. This downward erosion is the necessary concomitant of the
shoreward progress of wave erosion; for if the land were merely planed
away to the level of the wave troughs, the incoming waves would break
where shoal water was first reached and become ineffective at the water
margin. In feet, this spending of the force of the waves where the water is
so shallow as to induce them to break, increases at that point the erosive
power by pulsation, and thus brings about an interdependence of parts.
What may be called a normal profile of the submerged terrace is produced,
MON — VOL I 3
34 LAKE BONNEVILLE.
the parts of which are adjusted to a harmonious interrelation. If some
exceptional temporary condition ])roduces abnormal wearing of the outer
margin of the terrace, the greater deptli of water at that point jjermits the
incoming waves to pass with little impediment and perfonn their work of
erosion upon jjortions nearer the shore, thus restoring the equilibrium. If
exceptional resistance is opposed by the material at the water margin, ero-
sion is there retarded until the submerged terrace has been so reduced as to
permit the incoming waves to attack the land with a greater share of unex-
pended energy. Conversely, if there is a diminution of resistance at the
water margin, so as to pennit a rapid erosion, the landward recession of that
margin causes it to be the less exposed to wave action. Thus the landward
wear at the water margin and the downward wear in the several parts of
the submerged plateau are adjusted to an interdependent relation.
The Sea-Cliff— Wave crosiou, acting along a definite zone, may be rudely
compared to the operation of a horizontal saw; but the upper wall of the
saw cut, being without support, is broken away by its own weight and falls
in fragments, leaving a cliff at the shoreward margin of the cut. This wave-
wrought cliff requires a distinctive name to avoid confusion with cliffs of
other origin, and might with propriety in this discussion be called a lake-cliff;
but the term sea-cliff is so well established that it appears best to retain it.
One of the most noteworthy and constant characters of the sea-cliff is
the horizontality of its base. Being determined by wave erosion the base
must always stand at about the level of the lake on which the waves are
fonned. The material of the cliff is the material of the land from Avhich it
is carved. Its declivity depends partly on the nature of that material and
partly on the rate of erosion. If the material is unconsolidated, the inclina-
tion cannot exceed the normal earth slope; if it is thoroughly indurated, the
cliff may be vertical or may even overhang. If the rate of wave erosion is
exceedingly rapid, the cliff is as steep as the material will permit; if the rate
is slow, the inclination is diminished by the atmospheric waste of the cliff
face.
Figure 1 represents a cliff' on the shore of Great Salt Lake. The
material in this case is arenaceous limestone. At the base of the cliff may
be seen a portion of the accompanying wave-cut teiTace, and the fore-
SEA-GLIFFS.
35
gi-ound exhibits a portion of the associated beach. The hirge bowlders
of tlie foreground have an independent origin, but the shingle and otlier
material of the beach were derived from the erosion of the cliff and trans-
ported to their present position by the waves. Sheep Rock is overlooked
by the northern face of the Oquirrh mountain range, on which the Bonne-
ville shores are traced, and the partial view of the mountain face given in
the frontispiece shows a line of ancient sea-cliffs, originally as precipitous
as Sheep Rock but now shattered by frost and partially drajijcd by talus.
Fig. 1.— Sheep Bock, a SeaClilf on the shore of Great Salt Lake. From a photograph by C. K. Savage.
It will appear in the sequel that the distribution of sea-cliffs is some-
what peculiar, but this cannot be described until the process of littoral trans-
portation has been explained.
Tht Wave-Cut Terrace.-The submcrgcd plateau whose area records the land-
ward progi-ess of littDral erosion, becomes a terrace after the formative lake
36
LAKE BONNEVILLE.
has disappeared, and, as such, requires a distinctive name. It -will be called
the wave-cut terrace.
Its prime characteristics are, first, that it is associated witli a cliti";
second, that its upper margin, where it joins the clifF, is horizontal; and,
third, that its surface has a gentle inclination away from the cliff. There is
an exceptional case in which an island or a hill ot" the mainland has been
completely pared away by wave action, so that no cliff remains as a compan-
ion for the wave-cut terrace; but this exception does not invalidate the nile.
The lake ward inclination is somewhat variable, depending on the nature of
the mateiial and on the pristine acclivity of the land. It is greater where
the material is loose than where it is coherent; and greater where the ratio
of terrace width to cliff height is small. It is probal^ly conditi(jned also by
the tlirection of the current associated with the wind efficient in its production;
but this has not been definitely ascertained.
The width of the ten-ace depends on the extent of the littoral erosion,
and is not assignable. Its relative width in different parts of a given con-
tinuous coast depends entirely on the conditions determining the rapidity of
erosion, and the discussion of these at this point would be premature.
Sometimes a portion of the eroded material gathers at the outer edge
of the terrace, extending its profile as indicated in Figure 4.^
Figi;res 2 and 3 show ideal sections of cliffs and terraces, carved in one
case from soft material, in the other from hard. The station of the artist
Fig. 2.— Section of a Sea Clifl and Cut-Turracn in
Incoherent Material.
Fig. 3.— Section of a Sea ClitT and Cut-Terrace in Hard
Mnt«rial.
in sketching the view represented in the frontispiece was on a cut-terrace,
and a portion of it appears in the foreground.
' I C. Russell. Geological History of Lake Lahoutau, p. S9.
COOPEliATIOJT OF WAVES AND CURRENTS. 37
LITTORAL TRANSPORTATION.
Littoral transportation is performed by the joint action of waves and
currents. Usually, and especially when the wind blows, the water adja-
cent to the shore is stuTed by a gentle current flowing parallel to the water
margin. This carries along the particles of detritus agitated by the waves.
The waves and undertow move the shallow water near the shore rapidly to
and fro, and in so doing momentarily lift some particles, and roll others
forward and back. The particles thus wholly or partially sustained by the
water are at the same moment carried in a direction parallel to the shore by
the shore current. The shore current is nearly always gentle and has of
itself no power to move detritus.
When the play of the waves ceases, all shore action is arrested. When
the play of the waves is unaccompanied by a current, shore action is nearly
arrested, Ijut not absolutely. If the incoming waves move in a direction
normal to the shore, the advance and recoil of the water move particles
toward and from the shore, and effect no transfer in the direction of the
shore; but if the incoming waves move in an oblique direction the forward
transfer of particles is in the direction of the waves, while the backward
transfer, by means of the undertow, is sensibly normal to the shore, and
there is thus a slow transportation along the shore. If there were no cur-
rents a great amount of transportation would undoubtedly be performed in
this way, but it would be carried on at a slow rate. The transporting effect
of waves alone is so slight that only a gentle current in the opposite direc-
tion is necessary to counteract it. The concuiTence of waves and currents
is so general a phenomenon, and the ability of waves alone is so small, that
the latter may be disregarded. The practical work of transportation is
perfoi-med by the conjoint action of waves and shore currents.
In the ocean the causes of cuiTcnts are various. Besides wind currents
there are daily currents caused by tides upon all coasts, and it is maintained
by some physicists that the great currents are wholly or partly due to the
unequal heating of the water in different regions. But in lakes there are
no appreciable tides, and currents due to unequal heating have never been
discriminated. The motions of the water are controlled by the wind.
38 LAKE BONNEVILLE.
A long-contimied wind in <ine direction produces a set of currents har-
moniously adjusted to it. A change in the wind produces a change in the
currents, hut this adjustment is not instantaneous, and for a time there is
lack of harmony. The strong winds, however, bring about an adjustment
more rapidly than the gentle, and since it is to these that all important
littoral work is ascribed, the waves and cun-ents concerned in littoral trans-
portation may be here regarded as depending on one and the same wind.
A wind blowing directly toward a shore may be conceived of as jjiling
the superficial water against the shore, to be returned only by the undertow,
but, in fact, so simple a result is rarely observed. Usually there is some
obliquity of direction, in ^•irtue of which the shoreward current is partially
deflected, so as to produce as one of its effects a flow parallel to the shore,
or a littoral current. The littoral current thus tends in a direction hanno-
nious with the movement of the waves, passing to the right if the waves
tend in that direction, to the left if the waves tend thither.
To this rule there is a noteworthy exception. The undertow is not the
only return current. It frequently occurs that part of the water di-iven
forward by the wind returns as a superficial current somewhat opposed in
direction to tlie wind. If this cm-rent follows a shore it constitutes a littoral
current whose tendency is opposed to that of the waves. Thus the littoral
current may move to the right while the waves tend tt > the left, and vice versa.
In every such case the direction of transportation is the direction of the
littoral current.
The waves and undertow accomplisli a sorting of the detritus. The
finer portion, being lifted up by the agitation of the waves, is held in sus-
pension until carried outward to deep water by the undertow. The coarser
portion, sinking to the bottom more rapidly, can not be earned beyond the
zone of agitation, and remains as a ])art (tf the shore. Only the latter is
the subject of littoral transportation. It is called tihore drift.
With the shifting of the wind the direction of the littoral cun'ent on
any lake shore is occasionall}-, or it niay be frequently, reversed, and the
shore drift under its influence travels sometimes in one direction and some-
times in the other. In most localities it has a ])revailing direction, not nec-
essarily determined l)y the prevailing direction of the shore current, but
THE HIGHWAY OF THE SHORE DRIFT. 39
rather by the direction of that shore current which accompanies the greatest
waves. This is frequently but not always the direction also of the shore
current accomjianing the most violent storms.
The source of shore drift is two-fold. A large part is derived from the
excavation of sea-cliffs, and is thus the product of littoral erosion. From
every sea-cliff a stream of shore drift may be seen to follow the coast in one
direction or the other.
Another part is contributed by streams depositing at their mouths the
heavy part of their detritus, and is more remotely derived from the erosion
of the land. The smallest streams merely reinforce the trains of shore drift
flowing from sea-cliffs, and their tribute usually cannot be discriminated.
Larger streams furnish bodies of shore drift easily referred to their sources.
Streams of the first magnitude, as will be explained farther on, overwhelm
the shore drift and produce structures of an entirely different nature, known
as deltas.
The Beach—The zoue occupied by the shore di-ift in transit is called the
heach. Its lower margin is beneath the water, a little beyond the line where
the great storm waves break. Its upper margin is usually a few feet above
the level of still water. Its profile is
steeper upon some shores than others, but
has a general facies consonant with its
wave-wrought origin. At each point in
the i^rofile the sloije represents an equilib-
^ ^ ^ 1 Fig. 4.— Section of a Beach.
rium in transjjorting power between the
inrushing breaker and the outflowing undertow. Where the undertow is
relatively potent its efficiency is diminished by a low declivity. • Where
the inward dash is relatively potent the undertow is favored by a high de-
clivity. The result is a sigmoid profile of gentle flexure, upwardly convex
for a short space near its landward end, and concave beyond.
In horizontal contour the beach follows the original boundary between
land and lake, but does not conform to its irregularities. Small indentations
are filled with shore di'ift, small projections are cut away, and smooth, sweep-
ing curves are given to the water margin and to the submerged contours
within reach of the breakers.
40
LAKE BONNEVILLE.
The lieach graduates insensibly into the wave-cut terrace. A cut-terrace
lying in the route of shore drift is alternately Imried ^)y drift and swept
bare, as the conditions ot wind and breaker vary. Tlie cut-and-built ter-
race (Figure .'')), which owes its detrital extension to the agencies detennin-
ing the beach profile, may be regarded
as a forai intermediate between the
beach and the ciit terrace.
The Barrier. -Where the sublittoral
bottom of the lake has an exceedingly
gentle inclination the waves break at a
considerable distance from the water
Fig. 5.— Section of a Cntand Built Terrace.
margin. The most violent agitation of
Fig. 6. — Section of a Barrier.
the water is along the line of breakers; and the shore di-ift, depending upon
agitation for its transportation, follows the line of the breakers instead of
the water margin. It is thus built into a continuous outlying ridge at some
distance from the water's edge. It will be convenient to speak of this ridge
as a harrier
The barrier is the functional equiva-
lent of the beach. It is the road along
which shore drift travels, and it is itself
composed of shore drift. Its lakeward
face has the typical beach profile, and its crest lies a few feet above the
normal level of the Avater.
Between the barrier and the land a strip of water is inclosed, consti-
tuting a lagoon. This is frequently converted into a marsh by the accumu-
lation of silt and vegetable matter, and eventually becomes completely filled,
so as to bridge over the interval between land and barrier and convert the
latter into a normal beach.
The beach and the barrier are absolutely dependent on shore drift for
their existence. If the essential contiinious supply of moving detritus is cut
off, not only is the structure demolished l)y the waves which formed it, but
the work of excavation is carried landward, creating a wave-cut teiTace and
a cliff.
The principal elements of the theory of shore-drift deposits here set
GEOMETRIC RATIO OP EFFECT TO CAUSE, 41
forth are tacitly postulated by many writers on the construction of harbor
and coast defenses. According to Cialdi' the potency of currents in con-
nection with waves was first announced by Montanari; it has been concisely
and, so fixr as appears, independently elucidated by Andrews.^
Still water level is the datum with which all vertical elements of the
profile of the beach and barrier are necessarily compared; and, referred to
this standard, not only does the maximum height of the beach or barrier
vary in thflferent parts of the same shore, liut the profile as a whole stands
at different heights.
The explanation of these inequalities dej)ends in part on a principle of
wide application, which is on the one hand so important and on the other so
frecpiently ignored that a paragraph may properly be devoted to it, by way
of digression. There are numerous geologic processes in which quantitative
variations of a causative factor work immensely greater quantitative varia-
tions of the effect. It is somewhat as though the effect was proportioned to
an algebraic power of the cause, but the relation is never so simple. Take,
for example, the transportation of detritus by a stream. The variable cause
is the volume of water; the variable effect is the amount of geologic work
done — the quantity of detritus transported. The effect is related to the
cause in three different ways: First, increase of water volume augments the
velocity of flow, and with increase of velocity the size of the maximmn parti-
cle which can be moved increases rapidly. According to Hopkins, the size
of the maximum fragment which can be moved varies as the sixth power of
the velocity, or (roughly) as the f power of the volume of water. Second,
the increase of velocity enlarges the capacity of the water to transport detritus
of a given character; that is, the per cent of load to the unit of water is in-
creased. Third, increase in the niunber of unit volumes of water increases
the load pro rata. The suimnation of these three tendencies gives to the
flooded stream a transporting power scarcely to be compared with that of
the same stream at its low stage, and it gives to the exceptional flood a
' Loc. cit., p. 394, et seq. Cialdi himself maintains at great length that the work is performed by
waves, and that the so-called shore current, a feeble peripheral circulation observed in the Mediter-
ranean, is (jualitatively and quantitatively incompetent to jiroduce the observed results. Whether he
would deny the efflciency of currents excited by the same winds which produce the waves is not clearly
apparent
*■ Trans. Chicago. Acad. Sci., vol. a, p. 9.
42 LAKE BONNEVILLE.
power greatly in excess of the nomaal or annual flood. Not only is it time
that the work accomplished in a few days during' the height of the chief flood
of the year is greater than all that is accomplished during the remainder of
the year, but it may even be true that the eflect of the maximum flood of
the decade ftr generation or century surpasses the combined efl"ects of all
mmor floods. It follows that the dimensions of the channel are established
by the great flood and adjusted to its needs.
In littoral transportation the great storm bears the same relation to the
minor storm and to the fair-weather breeze. The waves created by the
great storm not only lift more detritus from each unit of the littoral zone,
but they act upon a broader zone, and they are competent to move larger
masses. The currents which accompany them are correspondingly rapid,
and carrv forward the augmented shore di'ift at an accelerated rate. It fol-
lows that the habit of the shore, including not only the maximum height of
the beach line and the height of its profile, but the dimensions of the wave-
cut terrace and of various other wave products presently to be described, is
determined by and adjusted to the great storm.
It should be said by way of qualification that the low-tide stream and
the breeze-lifted wave have a definite though subordinate influence on the
topographic configuration. After the great flood has passed by, the shrunken
stream works over the finer debris in the bed of the great channel, and by
removing at one place and adding at another shapes a small channel adjusted
to its volume. After the great storm has passed from the lake and the storm
s^vell has subsided, the smaller waves of fair weather construct a miniature
beach profile adapted to their size, superposing it on the greater profile.
This is done by excavating shore drift along a narrow zone under water and
throwing it up in a narrow ridge above the still water level. Thus, as early
perceived by De la Beche^ and, Beaumont,^ it is only for a short time innne-
diately after the passage of the great storm that the beach profile is a simple
curve; it comes afterward to be inteiTupted by a series of superposed
ridges produced by storms of difl"erent magnitude.
Reverting now to the special conditions controlling tlu; profiles of beach
or barrier at an individual locality, it is evident that the chief of these is the
' Mauu.al of Geology, Pbiladelpliia, 1832, p. 72. « Lefoiis, p. 22(5 ami plato IV.
THE FETCH OF WAVES, 43
magnitude of the largest waves breaking there. The size of the waves at
each locahty depends on the force of the wind and on its direction. A wind
bkiwing from the shore lakeward produces no waves on that shore. One
from the opposite shore produces waves whose height is approximately pro-
portional to the square root of the distance through which they are propa-
gated, provided there are no shoals to check their ^augmentation. For a
given force of wind, the greatest waves are produced when the direction is
such as to command the broadest sweep of water before their incidence at
the particular spot, or in the technical phrase, when the fetch is greatest.
A second factor is found in the configuration of the bottom. Where
the off-shore depth is great the imdertow rapidly returns the water driven
forward by the wind, and there is little accumulation against the shore; but
where the off-shore depth is small the wind piles the water against the shore,
and produces all shore features at a relatively high level.
The Subaqueous Ridge.-Various writers liave mentioned low ridges of sand or
gravel running parallel to the shore and entirely submerged. As the origin
of such ridges is not understood, they have no fixed position in the pres-
ent classification, and they are placed next to the barrier only because of
similarity of form. The following description was published by Desor in 1 851 :
An example of tbis character occurs on the northern shore of Lake Michigan, not
far from the fish station of Bark Point (Pointe aux J5corces), under the lee of a prom-
ontory, designated on the map as Point Patterson. Here, the shore, after running due
east and west for some distance, bends abruptly to the northeast. The voyageur com-
ing from the west, after having passed Point Patterson, is struck by the appearance of
several bands of shallow water, indicated by a yellowish tint. These bands, which
appear to start from the extremity of the point, are caused by subaqueous ridges,
which spread, fan-like, to the distance of nearly half a mile to the east, being from
three to ten yards wide, and from five to ten feet above the general bed of the lake, at
this point. They are not composed, like the flats, of fine sand, but of white limestone
pebbles, derived from the adjacent ledges, with an admixture of granitic pebbles, some
of which are a foot in diameter. It is difficult to conceive of currents suificiently
Ijowerful to transport and arrange such heavy materials, and yet we know of no other
means by which this aggregation could have been accomplished.
These subaqueous ridges afford, on a small scale, an interesting illustration of the
formation of similar ridges now above water. If the north coast of Lake Michigan
were to be raised only twenty feet, such a rise would lay dry a wide belt of almost
level ground, on which these ridges would appear conspicuously, not unlike those
which occur on the south shores of lakes Erie and Ontario, and thus confirm the
views of Mr, Whittlesey, that most of these ridges are not ancient beaches, but have
been formed under water, by the action of currents,'
' Foster aud Whitney's " Geology of f he Lake Superior Land District." Part 2, p. 258.
44 LAKE BONNEVILLE.
Wliittlesey describes no examples on existing coasts, but refers to them
as familiar features and relegates to their category numerous inland ridges
associated with earlier water surfaces in the basins of Lakes Erie, (Jntario,
and Michigan. He says that "their composition is luiiversally coarse water-
washed sand and fine gravel", while beaches consist of "clean beach sand
and shingle"; and alsoJ:hat beaches are distinguished from subaqueous ridges
by the fiict "that the foiTner are narrow and are steepest on the lake side,
resembling miniature terraces."'
Having personally observed many of the inland ridges described by
Wliittlesey and recognized them as barriers, having failed or neglected to
observe ridges of this subaqueous type in the Bonneville Basin, and having
independent reason to believe that the waters of Lakes Michigan, Erie, and
Ontario have recently advanced on their coasts, I leaped to the conclusion
that the ridges seen by Desor beneath the water of Lake Michigan, as well
as the subaqueous ridges mentioned without enumeration by Whittlesey,
were formed as barriers or spits at the water surface and were subsequently
submerged by a rise of the water.^ In so doing- I ignored an im[)ortant
observation by Andrews, who, writing of the beach at the head of Lake
Michigan, describes "a peculiarity in the contour of the deposit, which is
uniform in all the sand shores of this part of the coast. As you go out into
the lake, the bottom gradually descends from the water line to the depth of
about five feet, when it rises again as you recede from the shore, and then
descends toward deep water, forming a siibaqueous ridge or 'bar' jiarallel
to the beach and some ten or twenty rods from the shore." ^ It is impossible
to regard this sand ridge as a beach or barrier sulimerged by the rise of the
lake, for it stands within the zone of action of storm waves, and no mole
of loose debris can be assumed to successfully oppose their attack. It is to
be viewed rather as a product of wave action, or of wave and cuiTent action,
under existing relations of land and lake.
The subject is advanced by Russell, who visited the eastern shore of
Lake Michigan in 1884. He says:
Bars of anotber character are also formed along lake margins, at some distance
from the land, which agree in many ways with true barrier bars, but differ in being
' Fresh-water Glaci.il Drift of the Northwestern States. By Charles Whittlesey. Sniithsoniao
ContribntioM No. 197. W-aHhington, 1S66, pp. 17, lit.
'Fifth Ann. Rcpt. U. S. Gool. Survey, p. 111. 'Traus. Chicago Acad. Sci., vol. ", p. 14.
SUBAQUEOUS RIDGES. 45
composed of homogeneous, fine material, usually saud, and in not reaching the lake
surface.
The character of structures of this uature may be studied about the shores of
Lake Michigan, where they can be traced continuously for hundreds of miles. There
arc usually two, but occasionally three, distinct sand ridges; the first being about 200
feet from the land, the second 75 or 100 feet beyond the first, and the third, when
present, about as far from the second as the second is from the first. Soundings on
these ridges show that the first has about 8 feet of water over it, and the second usually
about I'i; between, the depth is from 10 to 14 feet. From many commanding points,
as the summit of Sleeping Bear Bluff, for example, these submerged ridges may be
traced distinctly for many miles. They follow all the main curves of the shore, with-
out changing their character or having their continuity broken. They occur in bays
as well as about the bases of promontories, and are always composed of clean, homo-
geneous sand, although the adjacent beach may be composed of gravel and boulders.
They are not shore ridges submerged by a rise of the lake, for the reason that they
are in harmony with existing conditions, and are not being eroded or becoming cov-
ered with lacustral sediments.
In bars of this character the fine debris arising from the comminution of shore
drift appears to be accumulated in ridges along the line where the undertow loses its
force; the distance of these lines from the land being determined by the force of the
storms that carried the waters shoreward. This is only a suggested explanation,
however, as the complete history of these structures has not been determined.'
In the survey of these lakes by the U. S. Engineers, numerous inshore
soundings were made, and while these do not fall near enough together to
determine the configuration of subaqueous ridges, they serve to show whetlier
the profile of the bottom descends continuously from the beach lakeward.
A study of the original manuscrij)t sheets, which give fuller data than the
published charts, discovers that bars sunilar to those described by Russell
occur along the eastern coast of Lake Michigan wherever the bottom is sandy,
being most frequently detectible at a depth of 13 feet, but ranging upward
to 3 feet and downward to 18 feet. At the south end of the lake they are
not restricted to the 5-foot zone indicated by Andi-ews, but range to 13 feet.
A single locality of occurrence was found on the shore of Lake Erie, but
none on Lake Ontario.
These ridges constitute an exception to the. beach profile, and show that
the theory of that profile given above is incomplete. Under conditions not
yet apparent, and in a manner equally obscure, there is a rhytlunic action
along a certain zone of the bottom. That zone lies lower than the troudi
between the greatest storm waves, but the water upon it is violently oscil-
'Geol. Hist, of Lake Lahontan. pp. 92-93.
46 LAKE BONNEVILLE.
lated by the jjassing waves. The same water is translated hikeward })y tlie
undertow, and the surface water above it is transhxted kindward by the wind,
while both move with the shore current parallel to the beach. The rhythm
may be assumed to arise from the interaction of the oscillation, the land-
ward current, and the undertow.
LITTORAL DEPOSITION.
The material deposited by shore processes is, first, shore tb-ift; second,
stream drift, or the detritus delivered at the shore by tributary streams
Increasing depth of water is in each case the condition of littoral deposi-
tion. The structures produced by the deposit of shore drift, although some-
what varied, have certain conmion features. They will be treated under
the generic title of embankments. The sti-uctures produced by the dejjosit
of stream drift are deltas.
EMBANKMENTS.
The current occupying the zone of the shore drift and acting as the
coagent of littoral transportation has been described as slow, but it is insepa-
rably connected with a movement that is relatively rapid. This latter, which
may be called the off-shore current, occupies deeper water and is less impeded
by friction. It may in some sense be said to drag the littoral current along
with it. The momentum of the off-shore current does not permit it to fol-
low the sinuosities of the water margin, and it sweeps from point to point,
carrying the littoral current with it. There is even a tendency to generate
eddies or return currents in embayments of the coast. The off-shore cur-
rent is moreover controlled in part by the configuration of the bottom and
by the necessity of a return current. The littoral current, being controlled
in large part by the movements of the off-shore current, separates from the
water margin in three ways: first, it continues its direction unchanged at
points where the shore-line turns landward, as at the entrances of Ijays; sec-
ond, it sometimes turns from the land as a surface current; third, it some-
times descends and leaves the water margin as a bottom cun-ent.
In each of these three cases deposition of shore di-ift takes place by
reason of the divorce of shore cuirents and wave action. The depth to
THE GENESIS OF SPITS. 47
which wave agitation sufficient for the transportation of shore di-ift extends
is small, and when the littoral current by leaving the shore passes into
deeper waters the shore di-ift, unable to follow, is thrown down.
When the current holds its direction and the shore-line diverges, the
embankment takes the form of a S2nt, a Jiook, a hat; or a loop. When the
shore-line holds its course and the current diverges, whether superficially
or by descent, the embankment usually takes the form of a terrace.
The spit.-When a coast line followed by a littoral current turns abruptly
landward, as at the entrance of a bay, the current does not turn with it, but
holds its course and passes from shallow to deeper water. The water be-
tween the diverging current and coast is relatively still, although there is
communicated to the portion adjacent to the current a slow motion in the
same direction. The waves are propagated indifferently through the flow-
ing and the standing water, and reach the coast at all points. The shore
drift can not follow the deflected coast line, because the waves that beat
against it av^ unaccompanied by a littoral current. It can not follow the
littoral current into dee^) water, because at the bottom of the deep water
there is not sufficient agitation to luove it. It therefore stops. But the
supply of shore di-ift brought to tliis point by the littoral current does not
cease, and the necessary result is accumulation. The particles are carried
forward to the edge of the deep water and there let fall.
In this way an embankment is constructed, and so far as it is built it
serves as a road for the transportation of more shore di'ift. The direction
in which it is built is that of the littoral current. It takes the form of a
ridge following the boundary between the current and the still water. Its
initial height brings it just near enough to the surface of the water to enable
the wave agitation to move the particles of which it is constructed; and it
is naiTOw. But these characters are not long maintained. The causes
which lead to the consti'uction of the beach and the barrier are here equally
efficient, and cause the embankment to grow in breadth and in height until
the cross-profile of its upper surface is identical with that of the beach.
The history of its growth is readily deduced from the configuration of
its terminus, for the process of growth is there in progress. If the material
is coarse the distal portion is very slightly submerged, and is terminated in
48 LAKE BONNEVILLE.
the direction of o^rowtli by a steep slope, the suliaqueous "earth-sh)pe" of the
particular material. If the material is fine the distal ])ortioii is more deeply
submerg-ed, and is not so abru])tly tenuinated. The portion above water
is usually narrow throughout, and terminates without reaching the extrem-
ity of the embankment. It is flanked on the lakeward side by a submerged
plateau, at the outer edge of which the descent is somewhat steep. The
profile of the plateau is that normal to the beach, and its contours are con-
fluent with those of the beach or barrier on the main shore. Toward the
end of the embankment its width diminishes, its outer and limiting contour
turning toward the crest line of the spit and finally joining it at the sub-
merged extremity.
The process of construction is similar to that of a railroad embankment
the material for which is derived from an adjacent cutting, carted forward
along the crest of the embanlcment and dumped off at the end; and the sym-
metry of form is often more perfect than the railway engineer ever accom-
plishes. The resemblance to railway structures is very striking in the case
of the shores of extinct lakes.
As the embankment is carried forward and completed, contact between
the current and the inshore water is at first obstructed and finally cut off",
so that there is practically no communication of movement from one to the
other at the extremity of the spit. At the point of construction the mo^^ng
and the standing water are sharply differentiated, and there is hence no
uncertainty as to the direction of construction. The spit not only follows
the line between the current and still water, but aids in giving definition
to that line, and eventually walls in the current by contours adjusted to its
natui'al flow.
The Bar._If flic curreut determining the foraiation of a spit again touches
the shore, the construction of the embankment is continued imtil it spans
the entire interval. So long as one end remains free the vernacular of the
coast calls it a spit; but when it is completed it becomes a lar. Figure 7
gives an ideal cross-section of a completed embankment.
The bar has all the characters of the spit except those of the tenninal
end. Its cross-profile shows a })lateau bounded on either hand by a steep
slope. The surface of the plateau is not level, but has the beach profile, is
BAKS AT THE MOUTHS OF KIVEES. 49
slightly submerged on the windward side and rises somewhat above the
ordinary water level at the leeward margin. At each end it is continuous
with a beach or bairier. It receives
shore drift at one end and delivers it at
the other.
The bar may connect an island with
the shore or with another island, or it Fig. 7.-Section of a Lluear Kmbanknaut.
may connect two portions of the same
shore. In the last case it crosses the mouth either of a bay or of a river.
If maintained entire across the entrance to a bay it converts the water be-
tween it and the shore into a lagoon. At the mouth of a river its mainte-
nance is antagonized by the outflowing current, and if its integrity is estab-
lished at all it is only on rare occasions and for a short time. That is to
say, its full height is not maintained; there is no continuous exposed ridge.
The shore di'ift is, however, thrown into the river cuiTent, and unless that
current is sufficient to sweep it into deep water a submerged bar is tlu'own
across it, and maintains itself as a partial obstruction to the flow. The site
of this submerged bar is usually also the point at which the current of the
stream, meeting the standing water of the lake, loses its velocity and depos-
its the coarser paii; of its load of detritus. If the contribution of river drift
greatly exceeds that of shore di'ift, a delta is fomied at the river mouth, and
this, by changing the configuration of the coast, modifies the littoral current
and usually detennines the shore drift to some other course. If the contri-
bution of river drift is comparatively small it becomes a simple addition to
the shore drift, and does not interrupt the continuity of its transportation.
The bars at the mouths of small streams are constituted chiefly of shore drift,
and all their characters are determined by their origin. The bars at the
mouths of large streams are constituted chiefly of stream di-ift, and belong
to the phenomena of deltas.
On a preceding page the fact was noted that the horizontal contoiu's of
a beach are more regular than those of the original surface against which
it rests, small depressions being filled. It is now evident that the process of
filling these is identical with that of bar construction. There is no trenchant
line of demarkation between the beach and the bar. Each is a carrier of
MON I 4
50
LAKE BONNEVILLE.
shore drift, and each employs its first load in the construction of a suitable
road.
Plate IV represents a part of the east shore of Lake ]\Iichigan seen
from the hill back of Empire liluflfs. In the extreme distance at the left
stand the Sleeping Bear Blutl's, and somewhat nearer on the shore is a tim-
bered hill, the lakeward face of which is likewise a sea-cliff. A bar coimects
the latter with the land in the foreground and divides the lagoon at the right
from the lake at the left. The symmetry of the bar is marred l)y tlie for-
mation of dunes, the li<^ter portion of the shore-drift being taken ui) by
the wind and carried toward the right so as to initiate the filling of the
lagoon.
Figure 8 is copied from the U . S. Engineer map of a portion of the south
shore of Lake Ontario west of the mouth of the Genesee River. The orig-
FiG. 8. — Map of Braddook'B Bay and vicinity, N. T., showing headlands conneoted by Bars.
inal contour of the shore was there irregular, consisting of a series of salient
and reentrant angles. The waves have truncated some of the salients and
have united them all by a continuous bar, behind which several bays or
/
BARS ACROSS BATS.
51
ponds are inclosed. The movement of the shore drift is in this case from
northwest to southeast, and the principal source of the material is a point of
land at the extreme west, where a low cliff shows that the land is being
eaten by the Avaves.
The map in Figure d is also copied from one of the sheets published
by the U. 8. Engineers, and represents the bars at the head of 'Lake Supe-
rior. These illustrate several
elements of the preceding dis-
cussion. In the first place they
are not formed by the predomi-
nant winds, bufby those which
brinff the greatest waves. The
predominant winds are west-
erly, and produce no waves on
tin scoast. The shore cWft is de-
rived from the south coast, and
its motion is first westerly and
then northerly. Two bars are
exhibited, the western of which
is now protected from the lake
waves, and must have been com-
pleted before the eastern was
begun. The place of deposition of shore drift was probably shifted from
the western to the eastern by reason of the shoaling of the head of the lake.
The converging shores should theoretically produce during easterly storms
a powerful undertow, by which a large share of the shore drift A\'ould be
carried lakeward and distributed over the bottom. The manner in which
the bars terminate against the northern shore without inflection is explica-
ble lilvewise by the theory of a strong undertow. If the return current
* were superficial the bars would be curved at then- junctions with both
shores.
An instructive view of an ancient bar will be found in PL IX, repre-
senting a portion of the Bonneville shore line. The town of Stockton, Utah,
appears at the right. The plain at the left was the bed of the lake- The
-■--■ -r-
Fig. 9.— Map of the head of Lake Superior, eLowins Baj Bars.
52 LAKE BONNEVILLE.
storm waves, moving from left to riglit, carved the sea-cliflP which appears
at the base of the mountain at the k^ft, and di'ifting the material toward the
right built it into a great spit and a greater bar. The end of the s\nt is
close to the town. The bar, which lies slightly lower, having been fonned
by the lake at a lower stage of its water, sweeps in a broad curve across
the valley to the rocky hill on the opposite side, where the artist stood in
making the sketch.
The Hook.-Tlie line of direction followed by the spit is usually straight, or
has a slight concavity toward the lake. This form is a function of the lit-
toral current, to which it owes origin. But that current is not perpetual; it
exists only during the continuance of certain determining winds. Other
winds, though feebler or accompanied by smaller waves, nevertheless have
systems of currents, and these latter currents sometimes modify the form of
the spit. Winds which .simply reverse the du-ection of the littoral current
retard the construction of the embankment without otherwise affecting it;
but a cuirent is sometimes made to flow past the end of the spit in a direction
making a high angle with its axis, and such a current modifies its foim. It
cuts away a portion of the extremity and rebuilds the material in a smaller
spit joining the main one at an angle. If this smaller spit extends lake ward
it is demolished by the next stonn; but if it extends landward its position is
sheltered, and it remains a permanent feature. It not infi-equently happens
that such accessory si)its are formed at intervals during the construction of
a long embankment, and are preserved as a series of short branches on the
lee side.
It may occur also that a spit at a certain stage of its growth becomes
especially subject to some conflicting current, so that its noimal gi-owth
ceases, and all the shore drift transported along it goes to the construction
of the branch. The bent embankment thus produced is called a hook.
The currents efficient in the formation of a hook do not cooi)erate
simultaneously, but exercise their functions in alternation. The one, during
the prevalence of certain winds, brings the shore drift to the angle and
accumulates it there; the other, during the prevalence of other winds, de-
molishes the new structure and redeposits the material upon the other limb
of the hook.
HOOKS. 53
In case the land on which it is based is a slender peninsula or a small
island, past which the currents incited by various winds sweep with little
modification of direction by the local configuration, the hook no longer has
the sharp angle due to the action of two currents only, but receives a curved
form.
Hooks are of comparatively rare occurrence on lake shores, but abound
at the mouths of marine estuaries, where littoral and tidal currents conflict.
Plate V represents a recurved spit on the shore of Lake Michigan, seen
from a neighboring bluff. The general direction of its construction is from
left to right, but storms from the right have from time to time tiu-ned its end
toward the land and the successive recurvements are clearly discernible near
the apex.
The mole enclosing Toronto harbor on the shore of Lake Ontario is a
hook of unusual complexity, and the fact that its growth threatens to close
the entrance to the harbor has led to its thorough study by engineers.
Especially has its history been developed by Fleming in a classic essay to
Avhich reference has already been made. A hill of drift projects as a cape
from the north shore of the lake. The greatest waves reaching it, those
having the greatest fetch, are from the east (see Fig. 10), and the cooper-
ating current flows from east to west. As
the hill gradually yields to the waves, its
coarser material trails westward, building a
spit. The waves and currents set in mo-
ti( >n by southwesterly winds carry the spit
end northward, producing a hook. In the ric lo. -Diagram of Lake Ontario, to sbow tho
1 -1 J 1 1 ,1 Futch of Waves reaching Torouto fiom (liH'erent
past the westward movement has been the directions.
more powerful and the spit has continued to grow in that direction, its north-
ern edge being fringed Avith the sand ridges due to successive recurvements,
but the shape of the bottom has introduced a change of conditions. The water
at the west end of the spit is now deep, and the extension of the embank-
ment is correspondingly slow. The northward drift, being no longer sub-
ject to frequent shifting of position, has cumulative effect on the terminal
hook and gives it a greater length than the others. In the chart of the har-
bor (Fig. 11) the composite character of the mole is readily traced. It may
54
LAKE BO]S NEVILLE.
also be seen that the ends of the successive hooks are connected by a beach,
the work of waves generated within the harbor by northerly winds.^ It will
be observed furthermore that while the west end of the spit is continuously
fringed by recurved ridges its eastern part is (juite free from them. This
does not indicate that the spit was simple and unhooked in the early stages
of growth, but that its initial ridge has disappeared. As the cliflf is eroded.
Fig. 11. — Map of the harbor and peninsula (Ilook) at Toronto. From charts published by U. T. Hind, in 1854.*
its position constantly shifts landward, the shore current follows, and the
lakeward face of the spit is carried away so that the waves break over it,
and then a new crest is built by the waves just back of the line of the old
one.^ By this process of partial destruction and renewal the spit retreats,
keeping pace with the retreating clilf. At an earlier stage of the process
the spit may have had the position and form indicated by the dotted out-
line, but whatever hooks ft-iuged its inner margin have disappeared in the
process of retreat.
'The marsh occnpying part of the space between the spit and the inaiuland (Fig. It) is only
incidentally connected with the feature under discussion. A small stream, the Don, reaches the shore
of the lake within the tract protected from waves by the hook and is thus enabled to construct a delta
with its sediment.
-Report on the preservation and improvement of Toronto Harbor. In Supplement to Canadian
Journal, 1854.
'At the present time the spit is divided near the niiudle, a natural breach having been artificially
prevented from healing. The portion of the peninsula fringed by successive hooks stands as au island.
LOOPED BARS. 55
The landward shifting illustrated by the Toronto hook affects many
embaidvments, but- not all. It ordinarily occurs when the embankment is
built in deep water and the source of its material is close at hand. Wherever
it is known that an embankment has at some time been breached by the
waves, it may be assumed with confidence that retreat is in progress.
As retreat progresses the layers constituting- the embankment are trun-
cated at top, and new layers are added on the landward side. In the result-
ing structure the prevailing di}) is landward (Fig. 12), and it is thereby
distinguished from all other forms of lacustrine deposition. This structure
was first described and explained by Fleming, who observed it in a railway
cutting through an ancient spit.^
The Loop.- Just as the spit, by advancing until it rejoins the shore, becomes
a, bar, so the completed hook may with propriety be called a looj) or a looped
bar. There is, however, a somewhat different feature to which the name is
more strikingly applicable. A small island standing near the main-land is
usually furnished on each side with a spit streaming toward the land. These
spits are composed of detritus eroded from the lakeward face of the island,
against which beat the waves generated through the l)road expanse. The
currents accompanj-ing the waves are not unifoi-m in direction, but vary
witli the wind tlu'ough a wide angle; and the spits, in sympathy with the
varying direction of currents, are curved inward toward the island. If their
extremities coalesce, they constitute together a perfect loop, resembling,
when mapped, a festoon pendent from the sides of the island.
Such a loop in the fossil condition, that is, when preserved as a vestige
of the shore of an extinct lake, has the form of a crater rim, the basin of
the original lagoon remaining as an undfained hollow. The accompanying
illustration (PI. VI) represents an island of Lake Bonneville standing on the
-desert near what is known as the "Old River Bed." The nucleus of solid
rock was in this instance nearly demolished before the work of the waves
was arrested by the lowering of the water.
The Wave-built Terrace.-It has already bccu pointed out that when a separa-
tion of the littoral current from the coast line is lirought about bv a diverg-
ence of the current rather than of the coast line, there are two cases, in the
'Notes on the Daveuport gravel diift. Canaili.ui Joarnal, New Series, vol. 6, 1861, pp. 247-253.
56
LAKE BONNEVILLE.
first of which the current continues at the surface, while in the second it
dives beneath the surface. It is now necessary to make a further distinc-
tion. The cun-ent departing from the sliore, but remaining at tlie surface,
may continue with its original velocity or it may assume a greater cross-
section and a diminished velocity. In the first case the shore drift is built
into a spit or other linear embankment. In the second case it is built into
a terrace. The quantity of shore diift moved depends on the magnitude of
the waves; but the speed of transit depends on the velocity of the current,
and wherever that velocity diminishes, the accession of shore di-ift must
exceed the transmission, causing accumulation to take place. This accumu-
lation occurs, not at the end of the beach, but on its face, carrpng its entire
profile lakeward and producing by the expansion of its crest a tract of new-
made land. If afterward the water disappears, as in the case of an extinct
lake, the new-made land has the character of a terrace. A cun-ent which
leaves the shore by descending, practically produces at the shore a diminu-
tion of flow, and the resulting embankment is nearly identical with that of
a slackening superficial current.
The wave-built terrace is distinct from the wave-cut terrace in that it
is a work of construction, being composed entirely of shore drift, while the
wave-cut terrace is the result of excavation, and consists of the pre-existent
terrane of the locality. The wave-built terrace is an advancing embank-
ment, and its internal structure is characterized by a lakeward dip (Fig. 13).
It is thus contrasted with the retreating embaidiment (Fig. 12).
Fig. 12.— Section of a Linear Embaukmcnt retreating landward. Tliedolti-d line .sliiiws llie oiiyiu^il posili(in of tbe crest
i^^^^^i^^iiiiil^^^sl^Mlii^MSsJMi^^Si^^;.
Fig. 13.— Section of a Wave-built Terrace.
The surface of the wave-built terrace, considered as a whole, is level,
but in detail it is uneven, consisting of parallel ridges, usually curved. Each
WAVE-BUILT TERRACES. 57
of these is referable to some exceptional siorm, the waves of which threw
the shore ch-ift to an unusual height.
Wliere the shore drift consists wholly or in large part of sand, and the
prevailing winds are toward the shore, the wave-built terrace gives origin to
dunes, which are apt to mask its normal ribbed structure.
The locality most favorable for the formation of a wave-built terrace
is the head of a triangular bay, up which the waves from a large body of
water are rolled without obstruction. The wind sweeping up such a bay
carries the surface of the water before it, and the only return current is an
undertow originating near the head of the bay. The superficial advance of
the water constitutes on each shore a littoral current conveying shore drift
toward the head of the bay, and as these littoral currents are diminished
and finally entirely dissipated by absorption in the undertow, the shore di'ift
taken up along the sides of the bay is deposited. If the head of the bay is
acute, the first embankment built is a curved bar tangent to the sides and con-
cave toward the open water. To the face of this successive additions are
made, and a terrace is gradually produced, the component ridges of which
are approximately parallel. The sharpest curvature is usually at the ex-
treme head of the bay.
The converging currents of such a bay give rise to an undertow which
is of exceptional velocity, so that it transports with it not only the finest
detritus but also coarser mattei', such as elsewhere is usvially retained in the
zone of wave action. In effect there is a resorting of the material. The
shore drift that has traveled along the sides of the bay toward its head, is
divided into two portions, the finer of which passes out with the reinforced
undertow, while the coarser only is built into the terrace.
The v-Terrace and v-Bar.-It rcmalus to dcscribc a type of terrace for which no
satisfactory explanation has been reached. The shores of the ancient Pleis-
tocene lakes afford numerous examples, Ijut those of recent lakes are nearly
devoid of them, and the writer has never had opportunity to examine one
in process of formation. They are triangular in ground plan, and would
claim the title of delta were it not appropriated, for they simulate the Greek
letter more strikingly than do the river-mouth structures. They are built
against coasts of even outline, and usually, but not always, upon slight
58 LAKE BONNEVILLE.
salients, and they occur most freqiientl}' in the long, narrow arms of old
lakes. \
One side of the triangle rests against the land and the opposite angle
points toward the open water. The free sides meet the land with short
curves of adjustment, and appear otherwise to he normally straight, although
they exhibit convex, concave, and sigmoid flexures. The growth is by ad-
ditions to one or both of the free sides; and the nucleus appears always to
have been a miniature triangular terrace, closely resembling the final struct-
ure in shape. In the Bonneville examples the lake ward slope of the teiTace
is usually very steej) down to the line where it joins the preexistent slope
of the bottom.
There seems no reason to doubt that these embankments, like the
others, were built by currents and waves, and such being the case the for-
mative currents must have divercced from the shore at one or both the land-
ward angles of the terrace, but the condition detennining this divergence
does not appear.
In some cases the two margins appear to have been deteimined by cur-
rents ajiproaching the terrace (doubtless at different times) from oj^posite
directions; and then the terrace margins are concave outward, and their
confluence is prolonged in a more or less irregular point. In most cases,
however, the shore drift appears to have been carried by one cm'rent from
the mainland along one margin of the teiTace to the apex, and by another
current along- the remaining side of the terrace back to the mainland. The
contours are then either straight or convex.
In Lake Bonnevnlle it happened that after the best defined of these ter-
races had attained nearly their final width the lake increased in size, so that-
they Avere immersed beneath a few feet f)f water. Wliile the lake stood at
the higher level, additions were made to the terraces by the building of lin-
ear embankments at their outer margins. These were carried to the water
surface, and a triangular lagoon was imprisoned at eacli l(>ialit\-. The sites
of these lagoons are now represented by flat triangular basins, i-ach walled
in by a bar bent in the fonn of a V. These Ijars were at first observed
without a clear conception of the terrace on which they were founded, and
the name W-bar was applied. The V-bar, while a conspicuous feature of
a S. GEOLOGICAL SUPVEY
LAKE BONNEVILLE PLVH
I'LATS Ol' LOOl'Kl) AM) V-SllArKT) KM15AN K'MKNTS,
OBSERVED ON
TBK SHORES OF LAKE I{0.\NEVlEEi:.
o I 8 3 ■tOOO_ _
SCALt: t
arrows sfitiw
on 171 w/t/r/f
x liri/'f/d
1, Siill Mnixli , .■>■„, lit' I'.illii
•-', II. A'„.v/ B.i.-.; ,ir IJra\,r Crrrl. Uaii,/,
h'<.s;-ni'ir lUillr ,01,1 Hivrr Ui-il .
1.. SlIiWIllKW
■'>. Fri'tt o/' the Mouriliiui
6. Haxl Biixf , Drrp I'r JtU:
7 , U sill,- nl did Hirer Bed
\\,S\X\ U'f.y/ NtiAf o/' Fn.-irn Mnnritfiin,.
10,12 Prmxs I'liUev. rinir Wa-iia .s/nuu/
\'i , .Vf rt r StttrkLcn
.luliu.t Klcn \ L'o.liUi
DiMwn t>v C; Tlioiul<sou
TRIANGULAR TERRACES. 59
the Bonne'salle shores, is not believed to be a normal feature of lakes main-
taining a constant level.
DRIFTING SAND; DUNES.
The dune is not an essential shore feature, but is an accessory of fre-
quent occurrence.
Dunes are formed wherever the wind drifts sand across the land. The
conditions essential to their production are wind, a supply of sand, and
sterility or the absence of a protective vegetal growth. In arid regions
sterility is afforded by the climatic conditions, and the sand furnished by
river bars laid bare at low water, and by the disintegration of sand rocks,
is taken up 1)y the wind and built into dunes; but where rain is abundant,
accumulations of such sort are protected by vegetation, and the only sources
of sujjply are shores, either modern or ancient.
Shore drift nearly always contains some sand, and is frequently com-
posed exclusively thereof The undertow carries off the clay, which might
otherwise hold the sand particles together and prevent their removal by the
wind; and pebbles and bowlders, which, by their superior weight oppose
wind action, are less able to withstand the attrition of littoral transj)ortation,
and disappear by disintegration from any train of shore drift which travels
a considerable distance. Embankments are therefore apt to be composed
largely of sand; and the crests of embankments, being exposed to the air
during the intervals between great storms, yield dry sand to the gentler
winds.
The sand drifted from the crests of free embankments, such as barriers,
spits, and bars, quickly reaches the water on one side or the other. What
is blown to the lakeward side falls within the zone of wave action, and is
again worked Over as shore drift. What is blown to the landward side ex-
tends the area of the embankment, correspondingly encroaching on the
lagoon or bay.
Sand blown from the crests of embankments resting against the land,
such as beaches and terraces, will spread over the land if the prevailing
wind is favorabje. In cases where the prevailing Avind is toward the lake
the general movement of sand is, of course, in that direction, and it is merely
60 LAKE BONNEVILLE.
returned to the zone of the waves and readded to the shore drift; but where
the prevailing winds are toward the land, dunes are foiTned and slowly rolled
forward by the wind. The supply of diy sand afforded by beaches is com-
paratively small, and dunes of magnitude are not often formed from it. The
great sand magazines are wave-built terraces, and it is from these that the
trains of sand so formidable to agriculture have originated.
The sands accumulated on the shores of lakes and oceans now extinct
are sometimes so clean that vegetation acquires no foothold, and the wind
still holds dominion. The "oak openings" of Western States are usually
of this nature; and in the Great Basin there are numerous trains of dunes
conveying merely the sand accumulated on the shores of the Pleistocene
lakes.
One product of littoral deposition — the delta — remains undescribed;
but this is so distinct from the embankment, not only in form but in process
of construction, that its consideration will be deferred until the interrelations
of the three processes already described have been discussed.
THE DISTRIBUTIOlSr OF WAVE-WROUGHT SHORE FEATURES.
Upon every coast there are certain tracts undergoing erosion; certain
others receive the products of erosion, and the intervals are occupied by the
structures peculiar to transportation. Let us now inquire what are the con-
ditions determining these three phases of shore shaping.
It will be convenient to consider first the conditions of transportation.
In oi'der that a particular portion of shore shall be the scene of littoral trans-
portation, it is essential, first, that there be a supply of shore di-ift; second,
that there be shore action by waves and currents; and in order that the
local process be transportation simply, and involve neither erosion nor depo-
sition, a certain equilibrium must exist between the quantity of the shore
drift on the one hand and the power of the waves and cui-ri'uts on the other.
On the whole this equilibrium is a delicate one, but within certain narrow
limits it is stable. That is to say, there are certain slight varisUions of the
individual conditions of equilibrium, which distm-b the equilibrium only in
a manner tending to its immediate readjustment. For example, if the shore
DISTKIBUTIOJ!^ OF EUOSION AND DEPOSITION. 61
drift receives locally a small increment from stream drift, this increment, by
adding to the shore contour, encroaches on the margin of the littoral ciuTcnt
and produces a local acceleration, which acceleration leads to the removal
of the obstruction. Similarly, if from some temporary cause there is a local
defect of shore drift, the resulting indentation of the shore contour slackens
the littoral current and causes deposition, whereby the equilibrium is restored.
Or if the force of the waves is broken at some point by a temporary obstruc-
tion outside the line of breakers, as for example by a wreck, the local dimi-
nution of wave agitation produces an accumulation of shore drift whereby
the littoral cxirreut is narrowed and thus accelerated until an adjustment is
reached.
Outside the limits thus indicated everything which disturbs the adjust-
ment between quantity of shore drift and capacity of shore agents leads either
to progressive local erosion or else to progressive local deposition. The
stretches of coast which either lose or gain ground are decidedly in excess of
those which merely hold their own.
An excessive stipply of shore ch'ift over and above what the associated
curi'ent and Avaves are competent to transport leads to deposition. This
occurs where a stream of some magnitude adds its quota of debris. A mod-
erate excess of this nature is disposed of by the formation of a wave-built
terrace on the lee side of the mouth of the stream, that is, on the side toward
which flows the littoral current accompanying the greatest weaves. A great
excess leads to the formation of a delta, in which the stream itself is the con-
structing agent and the influence of waves is subordinate.
On the other hand, there is a constant loss of shore drift by attrition,
the particles in transit being gradually reduced in size until they are removed
from the littoral zone by the undertow. As a result of the defect thus occa-
sioned, a part of the energy of the waves is expended on the subjacent
terrane, and the work of transportation is locally accompanied by a sufficient
amount of erosion to replenish the wasting shore drift. For tlie maintenance
of a continuous beach in a permanent position, it appears to be necessary
that small streams shall contribute enough debris to compensate for the
waste by attrition.
62 LAKE BONNEVILLK.
Theoretically, transportation must be exchanged for erosion wherever
there is a local increase iu the magnitude of waves, and for deposition where
there is a local decrease of waves ; but practically the proportions of waves
are so closely associated with the velocities of the accompanying cuiTents
that their effects have not been distinguished.
The factor which most frequently, by its variation, disturbs the equi-
librium of shore action is the littoral current. It has already been pointed
out that wherever it leaves the shore, shore di-ift is deposited; and it is
equally true that wherever it comes into existence by the impinging of an
open-water current on the shore, shore diift is taken up and the terrane is
eroded. It has been shown also that the retardation of the littoral cm-rent
produces deposition, and it is equally true that its acceleration causes ero-
sion. Every variation, therefore, in the direction or velocity of the cmrent
at the shore has a definite effect in the determination of the local shore
process.
Reentrant angles of the coast are always, and reentrant cm'ves are
usually, places of deposition. The reason for this is twofold: first, currents
which follow the shore move with diminished velocity in passing reentrants;
second, cun-ents directed toward the shore escape from reentrants only by
undertow, and, as heretofore explained, build terraces at the heads of the
embayments.
Salient angles are usually eroded, and salient curves nearly always,
the reasons being, first, that a current following the shore is relatively swift
opposite a salient, and, second, that a current directed toward the shore is
apt to be divided by a salient, its halves being converted into littoral cur-
rents transporting shore drift in opposite directions aivaij from the salient.
Some salient angles, on the contrary, grow by deposition. Tliis occurs
where the most important current approaches by following the shore and is
thi-own off to deep water by a salient. The most notable instances ai-c found
on the sides of narrow lakes or arms of lakes, iu which case currents approach-
ing from the direction of the length are accompanied by greater waves than
those blown from the direction of the opposite shore, and therefore dominate
in the detei-mination of the local action.
SIMPLIFICATION OF COAST LINES. 63
It thus appears that there is a general tendency to the erosion of salients
and the filling of embayments, or to tlie simplification of coast outlines. This
tendency is illustrated not only by the shores of all lakes, but by the coasts of
all oceans. In the latter case it is slightly diminished by the action of tides,
which occasion currents tending to keep open the mouths of estuaries, but
it is nevertheless the prevailing tendency. The idea which sometimes ap-
pears in popular writings that embayments of the coast are eaten oiit by
the ocean is a survival of the antiquated theory that the sculpture of the
land is a result of "marine denudation." It is now understood that the diver-
sifies of land topography are wrought by stream erosion.
Figure 8, representing about seven miles of the shore of Lake Ontario,
illustrates the tendency toward simplification. Each bluff of the shore marks
the truncation by the waves of a cape that was originally more salient. Each
beach records the partial filling of an original bay. Each bar is a wave-
built structure partitioning a deep reentrant from the open lake. The la-
goons receive the detritus from the streams of the land and are filling; partly
for this reason there is a local defect of shore drift, and tlie coast is receding
by erosion; and by this double process the original reentrants are suffering
complete effacement. For the original coast line — a sinuous contour on a
surface modeled by glacial and fluvial agencies — will be substituted a rela-
tively short line of simple curvature.
The simplification of a coast line is a work involving time, and the
amount of work accomplished on a particular coast aflbrds a relative meas-
ure of the time consumed. There are many modif}'ing conditions — the
fetch of waves, the off-shore depth, the material of the land, the original
configuration, etc. — and these leave no hope of an absolute measure; but
it is possible to distinguish the young coast from the mature. When a
water level is newly established against land with sinuous contour, the first
work of the waves is the production of the beach profile. On the gentlest
slopes they do this by excavating the terrane at the point where they first
break and throwing the material shoreward so as to build a barrier. On all
other slopes they establish the profile by carving a terrace with its correla-
tive clifi". The coarser products of terrace-cutting gather at the outer edge
64 LAKE BONNEVILLE.
of the terrace, helping to increase its breadth ; the finer fall in deeper water
and help to equalize the off-shore depth. Tlie terrace gradually increases
by the double process of cutting and iiUing until it has attained a certain
minimum width essential to the transportation of shore (L-ift. This A\idth is
for each locality a function of the. size of the greatest waves. Before it is
reached, the fragments detached from the cliff linger but a short time on the
face of the ten-ace; after a few excursions uj) and down the slope they come
to rest at the edge of the deeper water. When it is reached — wlien the
beach profile is complete — the excavated fragments torn from the cliff no
longer escape from the zone of wave action, but are rolled to and fro l)y the
waves of every storm, lose their angles by attrition, and are drifted along
by the shore cun-ent. It may happen that the material of the cliff is a
gravel, already rounded by some earlier and independent process, but Avhen
this is not tlie case, the cut-terraces of adolescent and mature coasts are
distinguished by the angular fomis on the one hand and the rounded forms
on the other of the associated detritus. When the formation of shore drift
has once been begun, its further development and the development of effi-
cient shore currents are gradual and by reciprocation. The spanning of
minor recesses of the coast-line by its beach helps to smooth the way for
the shore current, and the current promotes the beach. Embankments come
later, when ways have been straightened for the current and shore drift,
and those first constructed usually attempt the partition of only small em-
bayments. The more extended and powerful shore currents, competent to
span the bays between the greater headlands, become possible only after
minor rugosities of coast and bottom have disappeared.
LoAV but nearly continuous sea-cliffs mark the adolescent coast; simple
contours and a cordon of sand, interspersed with high cliff's, mark the matui*e
coast. As a result of the inconstancy of the relations of land and water, it
is probable that all coasts fall under these heads, but Richthofen lias sketched
the features of the theoretic senile coast.^ As sea-cliffs retreat and terraces
grow broader the energy of the waves is distributed over a wider zone and
its erosive work is diminished. The resulting defect of shore drift permits
' Fuhrer fur Forscbungsreisende, p. 338.
ADOLESCENT, MATURE AND SENILE COASTS. 65
the erosion of embankments, and tlie withdrawal of their protection extends
the line of cliff; but eventually the whole line is driven Ijack to its limit
and erosion ceases. The cliffs, no longer sapped by the waves, yield to
atmospheric agencies and blend with the general topography of the land.
Shore drift is still supplied by the streams and is spread over the broad lit-
toral shoal, ^\■here it lies until so comminuted by the waves that it can float
away.
The length of the period of adolescence varies with local conditions.
Where the waves are powerful, maturity comes sooner than where they are
weak. It comes sooner, too, where the material to be moved by the waves
is soft or incoherent than where it is hard and tirm; and it comes early
where the submerged contours and the contour at the water's edge have
few irregularities. Different parts of the same coast accordingly illustrate
different stages of development. The shores of Lake Bonneville are in
general matui'e, but in small sheltered bays they are adolescent. The
shore of Lake Ontario is in general mature, being traced on a surface of
glacial drift, but near the outlet is a region of bare, hard rock disposed in
promontories and islands, and there much of the coast is adolescent.
The classic "parallel roads" of Glen Roy in Scotland illustrate the ado-
lescent type, and this although the local conditions favor rapid development.
The smooth contoiu's of the valley gave no obstruction to shore currents,
depth and length of lake permitted the raising of large waves, and a mantle
of glacial drift afforded material for shore drift; but the beach profile was
not completed, the bowlders of the narrow terraces are still subangular,
and there are no eml)ankments. It is fairly inferred that the time repre-
sented by each shore-line was short.
STREAM WORK; THE DELTA.
The detritus brought to lakes by small streams is overwhelmed by shore
drift and merges with it. The tribute of large streams, on the contrary,
overwhelms the shore drift and accumulates in deltas. In the formation of
a normal delta the stream is the active agent, the lake is the passive recipient,
and waves play no essential part.
MON I 5
66 LAKE liONNEVILLE.
Tlie process of delta formation depends almost wholly on the following
law: The ((qxidtij and compdence of a stream for the transporlatiou of detritus
are increased and diminished hij the increase and diminution of the velocity. 1 lie
capacity of a stream is measured by the total load of deljris of a given fine-
ness which it can cany. Its competence is measured by the maximiun size
of tlie jiartioles it can move. A swift current is able to transport both more
matter and coarser matter than a slow current. The competence depends
on tlie velocity of the water at the bottom of the chamiel, for tlie Lu-gest
particles the stream can move are merely rolled along tlie bottom. Finer
particles are lifted from the bottom by threads of current tending more <ir
less upward, and l)efore they sink again are carried forward by the general
tlow. Their suspension is initiated by the bottom current, but the length
and speed of their excursi(m depend on the general velocity of the current.
Capacity is therefore a function of the velocity of the more superticial threads
of current as well as of those which follow the bottom.
Suppose tliat a river freighted with the waste of the Jand is newly made
tributary to a lake. Its water flows to the shore, and shoots out thence
o^'er' the relatively still lake water until its momentum has been communi-
cated by friction to so large a body of water as to practically dissipate its
velocity. From the shore outward the velocity at the bottom is the velocity
of the lake water and not that of the river water, and is inconsiderable. The
entire load conse(][uently sinks to a final resting place and becomes a deposit.
The coarse particles go down in iimnediate contiguity to the shore. Tlie
finest are carried far out before they escape from the su})eiiicial stratum of
river water.
The sinking of thc! coarse material at the shore has tlie effect of 1)uild-
ing out a platform at the level of the bottom of the river cluumel. Po.stulate
the construction of this ])latform for some distance from the sliore without
any modification of the longitudinal profile of the river, the river surface
descending to the shore and then becoming horizontal. Evidently, the hor-
izontal })ortion has no energy of descent to propel it, and yet is opposed by
friction; its velocity is, therefore, retarded, its capacity and competence are
I It m said tbat some glacier-feil streams ou entering lakes pass iiuJer instead of over the lake
water and tbac i)eculiar delta features result, but tbese are uot fully described.
DELTA BUILDING. 67
consequently diminished, and it tb-ops some of its load, llie fall of detritus
builds u]) the bottom at the point where it takes place, and causes a check-
ing of the current immediately above (up stream). This in turn causes a
depo;;it; an<l a reciprocation of retardation ;uid deposition continues until
the profile of the stream has acquired a continuous grade from its mf>uth at
the extremity nf the new platform backward to some steeper part of its
channel — a continuous grade sufficient to give it a velocity adequate to its
load. Tlie postulate is, of course, ideal. The river does not in fact build
a level bed and afterward change it to a slope, but carries forward the whole
work at once, maintaining continuously an adjustment between its grade
and its work. Moreover, since the deposition begins at some distance from
the mouth, the lessening load does not require a uniform grade and does
not produce it. The grade diminishes gradually lakeward to the foot of the
deposit slope, so that the longitudinal profile is slightly concave upward.
At the head of the deposit slope there is often an abrupt change of grade.
At its foot, where the maximum deposit is made, there is an abrupt change
of a double character; the incline of the river surface is exchanged for the
horizontal plane of the lake surface; the incline of the river bottom is ex-
changed for the steeper incline of the delta front.
The river current is swifter in the middle than at the sides, and on a
deposit slope, where velocity is nicely adjusted to load, the slight retarda-
tion at the sides leads to deposition of suspended matter. A bank is thus
produced at either hand, so that the water flows down an elevated sluice of
its own construction. The sides are built up pari passu with the bottom,
but inasmuch as they can be increased only by overflow, they never quite
reach the flood level of the water surface. A river thus contained, and a
river channel thus constructed, constitute an unstable combination. So loner
as the bank approximates closely to the level of the surface at flood stage,
the current across the bank is slovyer than the current of the stream, and
deposits silt instead of excavating; but whenever an accidental cause so
far lowers the bank at some point that the current across it during flood
no longer makes a deposit, there begins an erosion of the bank which
increases rapidly as the volume of escaping water is augmented. A
side channel is thus produced, which eventually becomes deeper than the
68 LAKE BONNEVlLLli;.
main or oriq'inal cliannel and draws in the greater part or perlia]is all of the
water. The ability of" the new channel to drain the old one depends on two
things: first, the outer slope of the bank, from the circumstances of its con-
struction, is steeper than the descent of the bottom of the channel; second,
the first-made channel, although originally following the shortest route to
the lake, has so far increased its length by the extension of its mouth that
the water escaping over its bank may find a shorter route. The river
channel is thus shifted, and its mouth is transferred to a new point on the
lake shore.
Repetition of this process transfers the work of alluAnal deposition from
place to place, and causes the river to build a sloping plain instead of a
simple dike. The lower edge of the plain is everywhere equidistant from
the head of the deposit slope, and has therefore the fonu of a circular arc.
The inclination is in all directions the same, varying only with the dimin-
ishing grade of the deposit slope, and the fomi of the plain is thus approxi-
mately conic. It is, in fact, identical with the product of land-shaping known
as the alluvial cone or alluvial fan. The symmetry of the ideal form is
never attained in fact, because the process of shifting implies inequality of
surface, but the approximation is close in cases where the grade of the
deposit slope is high, or where the area of the delta is large as compared
with the size of the channel.
m
''&^////«ilyX^^Mi, .
Fin. 14.— Section of a Delta.
At the lake shore the manner of deposition is ditVcrcnt. The heavier
and coarser part of the river's detrital load, that which it j)ushes and rolls
along the bottom instead of earring by suspension, is emptied into the lake
and slides down the face of the delta with no impulse but that given by its
own weight. The slojje of the delta face is the angle of repose of this coarse
material, subject to such modification as may result from agitation by waves.
DELTA STRUCTURE. 69
The finer part of the detritus, that which is transported by sns]:)ension, is
carried beyond the delta face, and sinks more or less slowly to the bottom.
Its disti'ibution depends on its relative fineness, the extremely fine material
being widely diffused, and the coarser falling near the foot of the delta face.
The depth of the deposit formed from suspended material is greatest near
the delta and diminishes gradually outward, so that tlie sloj)e of the delta
face merges by a curve with the slope of the bottom beyond.
As the delta is built lakeward, the steeply inclined layers of the delta
face are superjiosed over the more level strata of the lake bottom, and in
turn come to support the gently inclined layers of the delta plain, so that
any vertical section of a normal delta exhibits at the top a zone of coarse
material, bedded with a gentle lakeward inclination, then a 7.one of similar
coarse material, the laminations of which incline at a high angle, and at
bottom a zone of fine material, the laminations of Avhich are gently inclined
and unite by curves with those of the middle zone.
The characters of the fossil delta, or the delta as it exists after the des-
iccation of the lake concerned in its formation, are as follows: The upper
surface is a terrace with the form of an alluvial fan. The lower slo})e or
face is steep, ranging from 10° to 25°; it joins the upper slope by an angle
and the plain below by a curve. The line separating the upper surface from
the outer slope or face is horizontal, and, in common with all other horizon-
tal contours of the structure, is approximately a circular arc. The upper
or landward limit of the upper surface is a line horizontally uneven, depend-
ing on the contours of the antecedent topography. The lower limit of the
face is a vertically uneven line, depending on the antecedent topography as
modified by lake sediments. The material is detrital and well rounded; it
exhibits well-marked lines of deposition, rarely taking the character of bed-
ding. The structure as seen in section is tripartite (Fig. 15). In the upper
division the lines of deposition are parallel to the upper surface of the delta;
in the middle division they are parallel to the steep outer face, and in the
lower division they are gently inclined. The separation of the middle divis-
ion from the lower is obscure. Its separation from the upper is definite and
constitutes a horizontal plane. The fossil delta is invariably divided into
two parts by a channel running from its apex to some part of its periphery
70
LAKE BONNEVILLE.
and occupied l)y a stream, the agent of its construction Ijccoming, under
changed conditions of base level, the agent of demolition.
The ftm-like outline of the normal delta is iiioditicd wlierever wave :ic-
tion lias an importance comparable with that of stream fiction. Among tlie
great variety of fonns resulting from the combination of tlic two agencies,
there is one wliidi repeats itself with suf-
ficient frequency to deserve special men-
tion. It occin-s where the force of the
)unt
tlie
delta is inconsiderable. In such case
the shore current from either direction
is deflected by the mass of the delta, and
wave action adjusts the contour of the
delta to conformitv with the deflected
shore current. If the ANave influences
from oj)posite directions are equal, the
delta takes the form of a symmetric tri-
aiiffle similar to that of tlu' V-terrace.
Numerous illustrations are to be seen
on the shores of Seneca and CaAiiga
Lakes, where the conditions are peculiarly favorable. The lake is long
and narrow, so that nil the efficient wave action is associated with strong
shore currents, and these alternate in dii'ection. The predominant rock of
the sides is a soft slude, so easilv triturated l)v tlie waves tliat the entire
product of its erosion escapes with the undertow, and no shore drift remains.
The sides are straight, and each tributary stream l)uilds out ii little proinon-
torv ;it its month, to wliicli the waves ffive form. Some of these triauii'ular
deltas (miiIxmIv perfectlv tlu' Greek letter, Init tliev turn tlu* aj)ex toward tla*
wati'i- instead of towanl tlw* laud.
Fig. 15. — Verlitul section in :i Delta, .sliowiuj; the i\,p\
cal siiccessiou of strata.
THE WALLING IN OF "WALLED" LAKES. 71
ICE WORK ; THE RAMPART.
This feature does not belong to lakes in general, but is of locjil and
exceptional occurrence. It was named the "Lake Rampart" by Hitchcock,
who gave the first satisfactory accoinit of its origin.' Earlier observations,
containing the germ of the exjjlanation of the phenomenon, wci-e made by
Lee^ and Adams.' A later and indepen-
dent explanation was given by White.*
Tn ignorance of ITitchcock's description,
I yave credit in the Fifth Amuial Keijort of
^ ' Fig. 16.— Section ol a r.nTiipni I.
the U. S. Geological Survey to White, and
myself proposed the name "Shore Wall." I now substitute Hitclicock's
name, "Rampart", being moved thereto not only by the priority and the
eminent fitness of the name, bnt by the consideration that "Shore Wall" is
liable to be confounded with "Sea Wall", a term applied on some marine
coasts to steep-faced endiankments of shingle.
The ice on the surface of a lake expands while forming, so as to crowd
its edge against the shore. A further lowering of tem})erature produces
contraction, and this ordinarily results in the opening of vertical fissures.
These admit the water from below, and by the freezing of that water they
are filled, so that when expansion follows a subsequent rise of temperature
the ice cannot assume its original position. It consequently increases its t( >t;d
area and exerts a second thrust upon the shore. Where the shorts is iil)rnpt,
the ice itself yields, either bv crushing at the margin or by tlm formation
of anticlinals elsewhere; but if the shore is generally shelving, the margin
of the ice is forced up the acclivity, and carries with it any 1)owlders or other
loose material about which it may have frozen. A second lowering of tem-
perature does not withdraw the protruded ice margin, but initiates other
cracks and leads to a repetition of the shoreward thrust. The process is
repeated from time to time during the winter, but ceases with the melting of
'Lake Ramparts in Vermont. By Clias. H. Hitchcock. In Proe. Am. Ass. Adv. Sci., vol. 1.3,
1860, p. 335.
^C. A. Lee. Am. Jour. Sci., vol. 5, 1822, pp. 34-37, and vol. 9, 1825, pp. 2.39-241.
'J. Adams. Am. Jour. Sci., vol. 9, 1825, p)(. 13(>-144.
*C. A. White. Am. Naturalist, vol. 2, IHi/.i, pp. 14G-149.
72 LAKE BONNEVILLE.
the ice in the spring. The ice formed the ensuing winter extends only to
the water margin, and hy the winter's oscilhitions of temperature can be
thrust Landward only to a certain distance, determined by the size of the
lake and the local climate. There is thus for each locality a definite limit,
beyond whicli the ])rojection of bowlders cannot l)e earned, so tliat all are
deposited along a common line, where they constitute a wall oi' ramjinrt.
The base of a, rampart stands somewhat above and beyond the ordinary
mai'gin of tlie water. It is parallel to the water margin, following its inflec-
tions. Its size is ])robably determined in fact by the supply of matenal, but
there must also be a limit dependent on the strength of the ice formed in the
given locality. Its material is usually coarse, containing bowlders such as
the waves generated on the same lake would be unable to move. These
iw.vy be either smooth or angular, heavy or light, the process of accunuda-
tion involvino- no discrimination.
Ramparts are not found on the margins of large lakes, for whatever
record the ice of winter may make is obliterated by the storm waves of sum-
mer. Neither do they occur on the shores of very deep lakes, for such do
not admit of a heavy coating of ice; and for the same reason they are not
found in wann climates. So far as the Avrit. is aware, they have never
been found in the fossil condition, except that in a single instance a series
of them serves to record very recent changes of level.
SUBMERGENCK AND EMERGENCE.
In tlie preceding discussion the general relation of the water surface to
the land has been assumed to be constant. In ])oint of fact it is subject to
almost continuous change, and its mutations motlify the products of littoral
shaping.
Lakes with outlet lower their water surfaces by con-ading the channel
of outflow. Lakes without outlet continually oscillate up and down with
changes of climate; Jind finally, all large lakes, as well as the ocejin, are
aftected by differential movements of the land. The series of displacements
which in the geologic past has so many times revolutionized the distribution
of laud and water, has not ceased; and earth movements are so nearly uni-
versal at the present time that there are few coasts which betray no sjTnntoms
THE COASTS OF RISING AND SINKING LANDS. 73
of recent elevation or subsidence. In this place it is unnecessary t(j consider
whetlier the relation of water snrftxce to land is affected by mutations of the
one or of tlie otlu-i'; and the terms emergence and submergence will be used
with the understanding tliat they apply to clianges in the relation without
reference to causes of change.
Tlie general effect of submergence or emergence is to change the
horizon at which shore ])rocesses ai'e carried on; and if a considerable
change of level is effected abruptly, the nature of the ])rocesses and the
character of their ])roducts are not materially modified. A submerged shore-
line retains its configuration until it is gradually buried by sediments. An
emerged shore-line is subjected to slow destruction by atmospheric agen-
cies. Only the delta is rapidly attacked, and that is merely divided into
two parts l)y the stream which formed it. In the case of submergence the
new shore constructed at a hi^'her horizon is essentially similar to the one
submerged. In the case of emergence the new shore constructed at a lower
horizon rests upon the smooth contours wrought by lacustrine sedimenta-
tion, and, finding in the configuration little that is incongruous witli its shore
currents, carves few cliffs and builds few embankments. The barrier is
usually one of its characteristic elements.
A slow and gradual submergence modifies the products of littoral action.
The erosion of sea-cliffs is exceptionally rapid, because the gradually deep-
ening water upon the wave-cut terraces relieves the waves from the task of
carving the terraces and enables them to spend their full force against the
cliffs. The cliffs are thus beaten back before the advancing tide, and their
precipitous character is maintained with constant change of position.
A rhythm is introduced in the construction of embankments. For each
level of the water surface there is a set of positions appropriate to the initia-
tion of embankments, and Avith an advancing tide these positions are suc-
cessively nearer and nearer the land ; but with the gradual advance of water
the position of embankments is not correspondingly shifted. The embank-
ment constructed at a low stage controls the local direction of the shore
current, even when its crest is somewhat submerged, and by this control it
determines the shore di-ift to follow its original course. It is only when the
submergence is sufficiently rapid to produce a considerable depth of water
74 LAKE BONNEVILLE.
over the crest of the embankment that a new embankment is initiated behind
it. The new embankment in turn controls tlie shore current, and by a rep-
etition of the process a series of embankments is produced whose crests
differ in height by considerable intervals.
A slow and gradual emergence causes the waves, at points of excava-
tion, to expend their energies upttn the terraces rather than the cliffs. No
great cliffs ui-e produced, but a wave-cut terrace is carried downward with
the receding tide. Then; is now no rliytlmi in the construction of embank-
ments. At each successive lower level the shore drift takes a course a little
farther lakeward, and is built into a lower embankment resting against the
outer face of the one just formed.
The delta is very sensitive to emergence. As soon as the lake water
falls from its edge, the formative stream, having now a lower point of dis-
charge, ceases to throw down detritus and begins the corrasion of its chan-
nel. It ceases at the same time to shift its course over the surface of the
original delta, l)ut retains whatever position it happened to hold when tlie
emergence was initiated. Coincidently it begins the constraction of a new
or secondary delta, the ajiex of wliicli is at the o^^ter margin of the original
structure. With continuous emei'gence a series of new deltas are initiated
at points successively farther lakeward, and there is pi-oduced a continuous
descending ridge divided by the chaimel of the stream.
THE DISCRIMINATION OF SHORE FEATURES,
A .shore is the common margin of dry land and a body of water. The
elements of its peculiar topography are little liable to confusion so long as
they are actually associated with land on one side and water on the other;
but after the water has been withdrawn, their recognition is less easy. They
consist merely of certain cliffs, terraces, and ridges; and cliffs, terraces,
and ridges abound in the topography of land surfaces. In the following
pages the topographic features characteristic of ancient shores will be com-
pared and contrasted with other topographic elements likely to create con-
fusion.
Such a discrimination as this lias not before been attempted, although
the principal distinctions upon wliich it is based have been the common
DISCRIMINATION OF SHORE FEATURKS. 75
property of geologists for many years. The contrast of stream terraces with
shore terraces was clearly set forth by Dana in the American Journal of
Science in 1849, and has been restated by Geikie in his Text-Book of Ge-
ology. It was less clearly enunciated by the elder Hitchcock in his Illus-
trations of Surface Geology.
CLIFFS.
A clitf is a tojwgraphic facet, in itself steep, and at the same time sur-
rounded by facets of less inclination. The only variety belonging to the
phenomena of shores is that to which the name "sea-cliflf " has been ap})lied.
It will be compared with the cliff of differential degradation, the stream cliff,
the coulee edge, the fault scarp, and the land-slip cliff.
The Cliff of Differential Degradation.-It is a familiar fjxct that cortaiu rocks, maiuly
soft, yield more rajjidly to the agents of ei-osion than certain other rocks,
mainly hard. It results from this, that in the progressive degradation of a
country by subaerial erosion the minor reliefs are generally occupied by
hard rocks while the minor depressions mark the positions of soft rocks.
Where a hard rock overlies one much softer, the erosion of the latter pro-
ceeds so rapidly that the former is sapjjed, and being deprived of its support
falls away in Ijlocks, and is thus wrought at its margin into a cliff. In re-
gions undergoing rajiid degradation such cliffs are exceedingly abundant.
It is the invariable mark of a cliff" oi differential degradation that the
rock of the lower part of its face is so constituted as to yield more rapidly
to erosion than the rock of the upper part of its face. It is strictly dependent
on th(! constitution and structure of the terrane. It may have any form, l)ut
since the majority of rocks are stratified in Ijroad, even sheets, and since tlie
most abrupt alternations of texture occur in connection with such stratifica-
tion, a majority of cliffs of differential degradation exhibit a certain uniformity
and parallelisin of parts. The crest of such a cliff is a line parallel to the
base, and other associated cliffs run in lines approximately parallel. The
most conspicuous of the cliffs of stratified rocks occur where the strata are
approximately horizontal; and these more often than any others have been
mistaken for sea-cliffs.
The Stream Cliff. -The most powerful agent of land erosion is the running
stream, and, in regions undergoing rapid degradation, corrasion by streams
76 LAKE BONNEVILLE.
so far exceeds the general waste of the surface that their channels are cut
down vertically, forming cliffs on either hand. Tliese cliffs are afterward
maintained hy lateral corrasion, which opens out the valley of the stream
after the establishment of a base level has checked the vertical corrasion.
Such cliffs are in a measure independent of the nature of the rock, and are
closely associated with the stream. They stand as a rule in pairs facing
each other and separated only by the stream and its flood plain. The base of
each is a line inclined in the direction of the stream channel and in the same
degree. The crest is not parallel thereto, l)ut is an uneven line conforming
to no simple law.
The Coulee Edge.-The viscosity of a lava stream is so great, and this i-is-
cosity is so augmented as its motion is checked l)y gradual cooling, that its
margin after congelation is usually marked by a cliff of some height. The
distinguishing characters of such a cliff are that the rock is volcanic, ^\•ith
the supei-ficial features of a subaerial flow. It has probably never been mis-
taken for a sea-cliff, and receives mention here only for the sake of giving
generality to the classification of cliffs.
The Fault Scarii.-Tlie faultiug of rocks consists in the relative displacement
of two masses separated by a fissure. The plane of the fissure is usually
more or less vertical, and by virtue of the displacement one mass is made
to project someA^'hat above the other. The portion of the fissure wall thus
brought to view constitutes a variety of cliff or escarpment, and has been
called a fault scarp. In the Great Basin such scai-jis are associated with a
great number of mountain ranges, appearing generally at their bases, just
where the solid rock of the mountain mass is adjoined by the detrital foot
slojie. They occasionally encroach upon the latter, and it is in siu-h case
that they are most conspicuous as well as most likel}- to ])e mistaken for
sea-cliffs. Although in following the mountain bases tliev do not varv
greatly in altitude, yet they never describe exact contours, Ijut ascend and
descend the slopes of the foot hills. Tlie crest of such a cliff is usually
closely parallel to the base for long distances, but this jtarallclism is not
aljsolute. The two lines gradually converge at either end of the displace-
ment. In exceptional instances they converge rapidly, giving the cliff a
somewhat abrupt termination, and in such case anew clifi'ai)pears en dchelon,
COMPARISON OF CLIFFS. 77
continuing the displacement with a slight ofiFset. In Chapter VIII these
cliffs are described at length and illustrated by views and diagrams.
The Land-Slip Cliff. -Tlic laud-slip dltfcrs from the fault chiefly in the fact
that it is a purely superficial phenomenon, having its Avhole history upon a
visible external slope. It occurs usually in unconsolidated material, masses
of which break loose and move downward short distances. The cliffs pro-
duced by their separation from the general or parent mass, are never of great
horizontal extent, and have no common element of form except that they
are concave outward. They frequently occur in groups, and are apt to con-
tain at their bases little basins due to the backward canting which forms
part of the motion of the sliding mass.
Comparison. -The sca-clift" differs from all others, first, in that its base is
horizontal, and, second, in that there is associated with it at one end or other
a beach, a barrier, or an embankment. A third valuable -diagnostic feature
is its uniform association with the terrace at its base; but in this respect it
is not unique, for the cliff of differential degradation often springs from a
terrace. Often, too, the latter is nearly horizontal at base, and in such case
the readiest comparative test is found in the fact that the sea-cliff is inde-
pendent of the texture and structure of the rocks from Avhich it is carved,
while the other is closely dependent thereon.
The sea-cliff is distinguished from the stream-cliff by the fact that it
faces an open valley broad enough and deep enough to permit the genera-
tion of efficient waves if occupied b}- a lake. It is distinguished from the
coulee edge by its independence of rock structure and by its associated ter-
race. It differs from the fault scai-p in all those peculiarities which result
from the attitude of its antecedent; the water surface concerned in the for-
mation of the sea-cliff is a horizontal plane; the fissure concerned in the
formation of the favilt scarp is a less regular but essentially vertical ])lane.
The former crosses the inequalities of the preexistent topography as a con-
tour, the latter as a traverse line.
The land-slip cliff is distinguished by the marked concavity of its face
in horizontal contour. The sea-cliff is usually couA-ex, or, if concave, its
contours are long and sweeping. The former is distinguished also by its
discontinuity.
78 LAKE BONNEVILLE.
TERRACES.
A terrace is a horizontal or nearly horizontal topographic facet inter-
rupting a steeper slope. It is a limited plain, from one edge of which the
ground rises more or less steeply, while from tlie opjjosite edge it descends
more or less stee})ly. It is the "tread"' of a topographic step.
Among the features peculiar to shores are three terraces : the wave-cut,
the Avave-built, and the delta. These will be compai-ed with tlie terrace by
differential degradation, the stream terrace, the moraine terrace, the fault
terrace, and the land-slip terrace.
The Terrace by Differential Degradation.-The SaUlO gCUCral cirCUmStaUCCS of Hlck
texture- which nnder erosion give rise to cliffs j^roduce also terraces, but the
terraces are of less frequent occurrence. The only case in which they are
at all abundant, and the only case in which they need be discriminated from
littoral terraces, is that in which a system of strata, heterogeneous in texture
and lying nearly horizontal, is truncated, either by a fault or by some erosive
action, and is afterwards subjected on the truncated section to atraosphei'ic
waste. The alternation of hard and soft strata gives rise under such cir-
cumstances to a series of alternating cliffs and terraces, the outcrop of each
hard stratum appearing in a more or less vertical cliff", and the outcrop of
each soft stratum being represented l)y a gently sloping terrace, united to
the cliff above by a curve, and, in typical exam})les, separated from the cliff
below by an angle.
The length of such terraces in the direction of the strike is nsuallv great
as compared with their w^idth from cliff' to cliff. They are never level in cross
profile, but (1) rise with gradually increasing slo])efrom the crest of one cliff
to the base of the next, or (2) descend from the crest of one cliff' to a medial
depression, and thence rise with gradually increasing slope to the base of the
next. The first case arises where the terrace is narrow or the dip of the
strata is toward the lower cliff, the second case where the teiTace is broad and
the (lip of the rocks is toward the up})er cliff. In the first case the drainage
is outward to the edge of the lower cliff; in the second it is toward the medial
depression, whence it escapes by Jie narrow channels carved througli tlic
rock of the lower cliff.
DEGRADATION TERRACES. 79
The Stream Terrace.-Tlic' coiiditioii of rapid crosiou ill ally region is u})lift. In
a tract which has recently been elevated, the rate of" degradation is iine({ual,
the waste of the water channels being more rapid than that of the surface in
general, so that they are deeply incised. Eventually, however, the corrasion
of the water channels so reduces their declivities that the velocities of current
suffice merely for the transportation outward of the detritus disengaged by
the general waste of surface. In other words, a base level is reached. Then
the process of lateral corrasion, always carried on to a certain extent, as-
sumes jirominence, and its results are rendered conspicuous. Each stream
wears its banks, swinging from side to side in its valley, always cutting at
one side, and at the other building a shallow deposit of alluvium, which con-
stitutes its flood plain. The valley, having before consisted of the river
channel margined on either side by a clift, now consists' of a plain bounded
at the sides by cliffs and traversed by the river channel.
If now the corrasion of the stream bed is accelerated by a new uplift
or other cause, a smaller valley is excavated within the first and at a lower
level. So much of the original flood plain as remains constitutes terraces
flanking the sides of the new valley. Outwardly one of these terraces is
bounded by the base of the old line of cliffs, which may by decay have lost
their vertical habit. Inwardly it is bounded by the crest of the new line of
cliHs i>roduced by lateral corrasion.
Acceleration of downward corrasion is Ijrought about in many ways.
As already mentioned, it may be produced by a new uplift, and this stimu-
lus is perhaps the most potent of all. It is sometimes produced by the
downtlirow of the tract to which the streams discharge, or, \\\\;\t is nearly
the same thing, by the degradation of stream channels in that tract. It is
also brought about, within a certain range of conditions, by increase of
rainfall; and finally, it always ensues sooner or later from the defect of
transported material. The general waste of the originally uplifted tract
undergoes, after a long period, a diminution in rapidity. The streams have
therefore less detritus to transport. Their channels are less clogged, and
they are enabled to lower them by corrasion. Perhaps it would be better
to say that after the immediate consequences of uplift have so far passed
away that an equilibrium of erosive action is established, the degradation of
80 LAKE BONNEVILLE.
the entire tract proceeds at a slow continuous rate, the sliglit variations of
whic'h are in a sense accidental. Lateral corrasion under such circumstances
coexists in all stream channels with downward corrasion, and is the more
important process; but the horizon of its action is continuously lowered by
the downward corrasion. The terraces which result represent onl}- the
stages of a continuous process.
In a great number of stream valleys, not one but many ancient flood
plains find record in terraces, so that the stream terrace is a familiar topo-
graphic feature.
When a stream meandering in a flood plain encroaches on a wall of
the valley and corrades laterally, it carries its work of excavation down to
the level of the bottom of its channel; and afterward, when its course is
shifted to some other part of the valley, it leaves a deposit of allu\'ium, the
upper surface of which is barely submerged at the flood stage of the stream.
The depth of alluvium on the flood plain is therefore measured by the ex-
treme depth of the current at high water It constitutes a practically even
sheet, resting on the undisturbed terrane beneath. When the stream finally
abandons it, and by carving a deeper channel, converts it into a terrace, the
terrace is necessarily bipartite. Above, it consists of an even layer of allu-
vial material, fine at top and coarse at bottom; below, it consists of the
preexistent formation, whatever that may be. Where the lower portion is
so constituted as to resist erosion, it loses after a long period its alluvial
blanket, and then the terrace consists simply of the floor of hard rock as
pared away by the meandering stream. The coarse basal portion of the
alluvium is tlie last to disappear; and if it contains Inird bowlders some of
these will sui'vive as long as the form of the terrace is recognizable.
The elder Hitchcock enumerated and described four types of stream
terrace: the lateral terrace, the delta teiTace (groui)ed by the writer with
shoi-e terraces), the gorge terrace, and the glacis terrace;' and Miller, whose
clear anal}'sis of stream terracing is tlie most recent contribution to the sub-
ject,^ adds the ampliitheater terrace, the junction terrace, and the fan ter-
race. Such detail is not required in this connection, but it is proper to dis-
' Illustrations of Surface Geology. By Edward Hitchcock, p. .5.
'River-Terracing: its Methods and their results. Bj Hugh Miller. In Proc. R<iyal Physical Soc,
vol. 7, 1«83, pp. 263-306.
STREAM TERRACES. 81
tiiio-uish the fan terrace from the lateral terrace, to which the phraseology
of the preceding jjaragraphs more particularly applies.
The fan terrace of Miller, as developed in a mountain country, has been
admirably described and figured by Drew, who speaks of it as an "alluvial
fan cut by a river", but gives no shorter title;' in the nomenclature of the
present chapter it is an alluvial-cone terrace.
Where a large stream flowing through an alluvial plain receives a small
tributary from an upland bordering the plain, the tributary often builds
an alluvial cone upon the margin of the plain. If afterward the large stream,
shifting its course over the plain, encroaches on the alluvial cone, it con-
verts it into a teiTace. The small stream acquires in this manner a lower
point of discharge and is induced to corrade a channel through its own
alluvial cone, dividing it into two parts. With reference to the valley of
the small stream, these parts are lateral terraces. With reference to the
valley of the large stream, they constitute together an alluvial-cone terrace.
The alluvial-cone terrace differs from the lateral terrace in that its surface
does not incline uniformly in the direction of the current of the stream it
overlooks, but inclines radially in all directions from a point at the side of
the valley.
The Moraine Terrace.- Wlieu au alluvlal plain OY alluvial couc Is built agaliist
the side or front of a glacier and the glacier is afterward melted away, the
alluvial surface becomes a terrace overlooking the valley that contained
the ice. The constructing stream may flow from the ice and gather its allu-
vium from the glacial debris, but it usually flows from the land. The slope
of the alluvial plain is detennined by the direction and other accidents of
the stream. Where the plain adjoins the glacier, it receives whatever debris
falls from the ice, and it may be said to coalesce initially with a morainic
ridge. Its internal constitution is partly alluvial and partly morainic. If
the morainic ridge is large, the plain does not become a moraine terrace.
If it is small, it falls away when the removal of the ice permits the margi
of the plain to assume the "angle of repose."
' AUnvial and lacustrine deposits and glacial records of the Upper-Indus Basin. By Fr(
Drew. Quart. Jour. Geol. Soc. London, vol. 29, 1873, pp. 441-471,
^Theallitvialfan o( Drew is the alluvial cone of American geologists, and there would beUbme
reasons for preferring fan to cone if it were necessary to employ a single term only. It is conveknent
to use them as synonyms, employing cone when the angle of slope is high, and fan when it is low
MON I 6
82
LAKE BONNEVILLE.
2-
Moraine teiTacos may be classified, after tlic uianiicr of moraines, as
lateral and troutal. The history of the lateral type is illustrated l)y V'v^.
1 7, representing in cross section the side of a glacier in an open valley. The
alluvium, rt, is built up syn-
chronously with the glacial
debris, f7, and the two interbed
and mingle at their junction.
When the ice melts, the face
of the deposit assumes under
gravity the ])rofile indicated
by the dotted line.
If the glacier diminishes
Fig. 17. -Ideal section, illustratiDg the formation of a Moraine Terrace (rradually, SUCCeSsive teiTaCCS
at the Siilo of a GLacier. *
are formed, and these fre-
quently overlap. In P'ig. 18 it is assumed that the ice profile had succes-
sively the positions of the dotted lines x and y. When it retreated to y, the ac-
cumulated deposit assumed the
profile ahc, and a new deposit
besran between the ice and the
face ftc. By subsequent ice
retreat the second deposit as-
sumed the profile def. As a
result of this process the ma-
terial of the terrace de overlies
unconfonnably the material of the terrace db.
An alluvial plain bordering the front of a glacier is apt to overlap the
ice and to include near its outer
margin not only morainic debris
but blocks of ice. "When the
Fig. 18. -Ideal section, showing the internal structure of gnmpcil
Lateral Moraine Terraces.
-|— ice melts, the overlapping de-
posit cannot assume the simple
earth-slope or angle of repose,
F,G. 19 _I,l..als.ction„f.Uuvialfin„,ga,..,inst Front Edge of GLuier. ^^^ i-gceiveS a huimilOcky, UIO-
rainic surface (Fig. 20).
MORAINE TERRACES,
83
So closely does the moraine terrace simulate the stream terrace tliat it
is usually undistiug-uislied.' The lateral tyi)e is identical in cross-profile
and in longitudinal profile, and,
unless portions of the morainic
ridge remain, has but one for-
mal difference: the contours of
its outer face, being determined
by the side of an ice stream,
are smootli curves of gentle flexure.
The Fault Terrace.-It somctunes occurs that two or more fault scarps with
throw in the same direction, run parallel with each other on the same slope,
thus dividing the surface into zones or tracts at various heights. Each of
these tracts contained between two scarps is a terrace. It is a dissevered
section of the once continuous general surface, divided by one fault from that
which lies above on the slope and by another from that which lies below. It
is the top of a diastrophic block, and its inclination depends upon the attitude
of that block. Usually the block is tilted in a direction opposite at once to
that of the throw of the limiting faults and to that of the general slope of the
country. This has the effect of giving to the terrace an inclination less steep
than that of neighboring plains, or (exceptionally) of inclining it in the oppo-
site direction.
In the direction of its length, which always coincides with the strike of
the faults, the terrace is not horizontal, but undulates in sympathy with the
general sui-face from which it has been cut.
The Land-Slip Terrace.-Tliis is closcly related in cross-profile to the fault ter_
race, but is less regular and is of less longitudinal extent. Its length is fre-
quently no greater than its width. The surface on which motion takes place
has a cross section outwardly concave, so that the sliding mass moves on an
arc, and its upper surface, constituting the terrace, has a less inclination
than in its original position. Frequently this effect is carried so far as to
incline the terrace toward the cliff which overlooks it, and occasionally the
' Its recognition was probably late. W. S. Green describes it in "The Higli Alps of New Zealand"
(London, 1883), and Chambeilln describes and names it in the Third Annual Report of the U. S. Geo-
logical Survey, p. 304. The name " moraine terrace " was provisionally attached by E. Hitchcock (Sur-
face Geology, pp. 6, 61) to a phenomenou not now regarded as a terrace.
84 LAKE BONNEVILLE.
edg'e of the terrace is connected with the cKflf in such way as to form a small
lake basin.
An even terrace of such origin is rarely observed. The surface is usually
luunmocky, and where slides occur in groups, as is their habit, the hillside
is thrown into a billowy condition suggestive of the surface of a terminal
moraine.
comparison.-The ouly fcaturc by which shore ten'aces are distinguished
from all terraces of other origin, is the element of horizontality. The wave-
cut terrace is hounded by a liorizontal line at its uj)per edge; the delta is
bounded l)y a horizontal line about its lower edge; and the wave-built ter-
race is a, horizontal plain. But the application of this criterion is rendered
diflRcult 1)\- th(^ fact tliat the terrace of differential degi'adatiou is not infre-
quently margined l)v liorizontal lines; while the inclinations of the stream
terrace and the moraine terrace, though universal and essential characters,
are often so small in amount as to be dithcult of recognition. The fault
terrace and land-slip terrace are normally so uneven that this character suf-
ficiently contrasts them with all shore features.
The Avave-cvit terrace agrees A\ith all the non-shore terraces in that it
is overlooked by a cliff rising from its upper margin, and usuallv differs in
that it merges at one end or l)oth with a beach, barrier, or embankment. It
is further distin^'uished from the terrace of differential deo-radation l)v the
fact that its contiguration is independent of the structure of the rocks from
which it is carved, while the latter is closely dependent thereon. In freshlv
formed examples, a further distinction mav be recognized in the mode of
junction of terrace and cliff. As viewed in protile, the wave-cut terrace
joins the associated sea-cliff by an angle, while in the profile wi-ought by dif-
ferential degradation, the terrace curves upward to meet the overlooking cliff.
The wave-cut terrace is distinguished from the stream terrace by tlu'
fact that it appears only on the margin of an oi)eu bnsiu broad enough for
the propagation of efficient waves, whereas the latter usually margins a nar-
row or restricted basin. In the case of broad terraces a further thstinction
is found in the fact that the shore terrace descends gently from its cliff to its
outer margin, whereas the stream terrace is normally level in cross section.
In fresh examples the alluvial capping of the stream terrace affords addi-
tional means of discrimination.
COMPARISON OF TERRACES, 85
The wave-cut terrace is distiuguislied from the moraine terrace by the
fact that its floor consists of the preexistent terrane in situ, the moraine ter-
race being a work of construction. The wave-cut terrace occurs most fre-
quently on saHents of the topography; its inner margin is a simpler curve
than its outer. The moraine terrace is found most frequently in reentrants;
its outer margin is a simpler curve than its inner.
There are certain cases in which the wave-formed and stream terraces
merge with each other and are difficult of separation. These occur in the
estuaries of ancient lakes, where the terraces referable to wave action are
confluent with those produced contemporaneously by the lateral corrasion
of streams. The stream being then tributary to the lake, it could not carry
its erosion to a lower level, and its zone of lateral corrasion was at its mouth
continous with the zone of wave erosion in the lake.
The wave-built terrace may be distinguished from all others Ijy the
character of its surface, which is corrugated with ])arallel, curved ribs. It
differs from all except stream and moraine terraces in its material, which is
wave-rolled and wave-sorted. It diff'ers from the stream terrace in that it
stands on a slope facing an open basin suitable for the generation of
waves.
The delta differs from all except the stream terrace and the moraine
terrace in its material and in its constant relation to a water way. Its mate-
rial is that known as stream drift. Its mass is alwa}'s divided by a stream
channel so as to lie partly on each bank ; its terminal contour is a convex
arc centering on some point of the channel ; and it is usuall}' confluent in
the ascending direction with the normal stream terrace. Indeed, when con-
sidered with reference to the dividing channel, it is a stream terrace ; and it
is only with reference to the lakeward margin that it is a shore terrace. It
is distinguished from the normal stream terrace by its internal structure.
The high inclination of the lamination of its middle member — formed by the
discharge of coarse detritus into standing water — is not shared by the stream
terrace, while its horizontal alluvium does not, as in the case of the stream
terrace, rest on the preexistent terrane. It is distinguished from simulating
phases of the moraine terrace by its outer contour, which is outwardly con-
vex and more or less in-egular, while that of the moraine terrace is straight
86 LAKE BONNEVILLE.
or simply curved. The frontal moraine terrace often affords a further dis-
tinction by the hummocky character of its outer face.
As the formation of the delta is independent of wave action, it may
and does take place in sheltered estuaries and in small basins. A small
lake interrupting the course of the stream may be completely filled by the
extension of the delta built at its upper extremity ; and when this has
occurred, there is nothing in the superficial phenomena to distinguish the
foi'mation from the normal flood plain.
The terrace of diff'erential degradation is further distinguished from all
shore teri'aces by the fact that, without great variations in width, it follows
the turnings of the associated cliff, conforming to it in all its salients and
reentrants. Where the shore follows an irregular contour, wave-cut ter-
races appear only on the salients, and in the reentrants only wave-built
terraces and deltas.
RIDGES.
Ridges are linear topographic reliefs. They may be broadly classed
into (1) those produced by the erosion or dislocation of the earth's surface,
and (2) those built uj)()n it Ijy superficial transfer of matter. In the first
class, the substance of the ridge is continuous with that of the adjacent plain
or valley ; in the second, it is not ; and this difference is so obvious that shore
ridges, which fall within the second class, are not in the least lialjle to be
confused with ridges of the first class. They will therefore be compared in
this place only with other imposed ridges. Of shore phenomena, the bar-
rier, the embankment, and the rampart are ridges. They will be contrasted
with the moraine and the osar.
The Moraine— The dctritus dcposited by glaciers at their lateral and termi-
nal margins is usualh' l)uilt into ridyes. Tlu^ material of these is fraff-
mental, heterogeneous, nnd unconsolidated. It includes large blocks, often
many tons in weight, and these are angular or subangular in form. Some-
times their surfaces are striated. The crest of the moraine is not liorizontal,
but descends with the general descent of the land on wliich it rests.
Moraines are found associated with mountain valleys, and also upon
open plains. In the first case their ci'ests are narrow, and their contours
are in general reorular. The lateral moraines follow the sides of the val-
COMPARISON OF RIDGES. 87
leys, often standing at a considerable height above their bottoms, and are
united by the frontals or terminals, which cross from side to side witli
curved courses whose convexities are directed down stream. The moraines
of plains have bi'oad, billowy crests abounding in conical hills and in small
basins.
The osar or Kame.-Tliese uaines are applied to an indirect product of glacial
action. It is multifarious in form, being sometimes a hill, sometimes a ridge,
and often of more complicated form. It doubtless embraces types that need
to be separated; but it is here sufficient to consider only the linear form.
As a ridge, its trend is usually in the direction of glacial motion. Its ma-
terial is water-worn gravel, sand and silt, with occasional bowlders. Its
contours are characteristically, but not invariably, irregular. Its crest is
usually, but not invariably, uneven; when even, it is parallel to the base or
to that upon which the base rests. In other words, the ridge tends to
equality of height rather than to horizontality.
Comparison. -The sliorc ridges are primarily distinguished from the glacial
ridges l)y the element of horizontality. The barrier and the emljankment
are level-topped, while the rampart has a level base and is so low tliat the
inequality of its crest is inconsiderable. It is only in exceptional cases and
for short distances that moraines and osars exhibit horizontality. Shore
ridges are further distinguished by their regularity. Barriers and embank-
ments are especially characterized by their smoothness, while smooth osars
are rare, and tlie only moraine with even contours is the lateral moraine •
associated with a narrow valley.
Other means of discrimination are afforded by the component materials,
and tlie moraine is thus clearly differentiated. The barrier and the embank-
ment consist usually of sand or iine gravel, from which both clay and larger
boAvlders have been eliminated. Except in immediate proximity to the sea-
cliff whose erosion affords the detritus, the pebbles and bowlders are well
I'ounded. The material of the rampart has no special qualities, but is of
local derivation, the ridge being formed simply by the scraping together of
superficial debris. The moraine contains heterogeneous material ranging
from fine clay to very large, angular blocks. The materials of the osar are
normally less rounded than those of normal shore ridges.
88 LAKE BONNEVILLE.
Certain osars of great length, even figure, and uniform lieight are dis-
tinguished from barriers by the greater declivaty of their flanks, and by the
fact that they do not describe contoiu's on the margins of Ijasins.
THE RECOGNITION OF ANCIENT SHORES.
The facility and certainty with which tlie vestiges of ancient water
margins are recognized and traced depend on local conditions. The small
waves engendered in ponds and in sheltered estuaries are far less efficient
in the carving of cliifs and the construction of embankments than are the
great waves of larger water bodies ; and the faint outlines they produce are
afterward more difficult to trace than those strongly drawn.
The element of time, too, is an important factor, and this in a double
sense. A water surface long maintained scores its shore mark more deeply
than one of brief duration, and its history is by so much the more easily
read. On the other hand, a system of shore topography from which the
parent lake has receded, is immediately exposed to the obliterating influence
of land erosion, and gradually, though very slowly, loses its character and
definition. The strength of the record is directly proportioned to the dura-
tion of the lake and inversely to its antiquity.
It will be recalled that in the preceding description the character of
horizontality has been ascribed to every shore feature. The base of the
sea-clitf and the coincident margin of the wave-cut terrace are hoi'izontal;
and so is the crest of each beach, barrier, embankment, and wave-built
terrace; and the}' not merely agree in the fact of horizontality, but fall
essentially into a common plane — a plane intimately related to the horizon
of the maximum force of breakers during storms. The outer margin of the
delta is likewise horizontal, but at a slightly lower level — the level of the
lake surface in repose. This diff"erence is so small that for the purpose of
identification it does not affect the practical coincidence of all the horizontal
lines of the shore in a single contour. In a region where forests aft'ord no
obstruction, the observer has merely to bring his eye into the plane once oc-
cupied by the water surface, and all the horizontal elements of shore topog-
raphy are projected in a single line. This line is exhibited to him, not
merely by the distinctions of light and shade, but by distinctions of color,
VALUE OF THE DISTANT VIEW. 89
due to the fact that the changes of inclination and of soil at the line influence
the distribution of many kinds of vegetation. In this manner it is often
possible to obtain from the general view evidence of the existence of a faint
shore tracing, which could be satisfactorily determined in no otlier way.
The ensemble of a faintly scored shore mark is usually easier to recognize
than any of its details.
It is proper to add that this consistent horizontality, wliich appeals so
forcibly and effectually to the eye, can not usually be verified by instru-
mental test. The surface of the "solid earth" is in a state of change,
whereby the vertical relations of all its parts are continually modified.
Wherever the surveyor's level has been applied to a fossil shore, it has been
found that the "horizon" of the latter departs notably from horizontality,
being warped in company with the general surface on whicli it rests. The
level, therefore, is of little service in the correlation of shore lines seen at
different places and not continuously traced; but when an ancient shore-line
has been faithfully traced through a basin, the determination by level of its
variations in height discovers the nature of displacements occurring since
its formation. It might appear that the value of horiz(intality as an aid to
the recognition of shores is consequently vitiated, but such is not the case.
It is, indeed, true that the accumulated warping and faiilting of a long
period of time will so incline and disjoint a system of shore features that
they can no longer be traced; but it is also true that the processes of land
erosion will in the same time obliterate the shore features tlieniselves. The
minute elements of orographic dis{)lacement are often paroxysmal, but so
far as observation informs us, the genei'al progress of such changes is slow
and gradual, so that, during the period for which shore tracings can with-
stand atmospheric and pluvial waste, their deformation is not sufficient to
interfere materially with their recognition.
CHAPTER III.
SHORES OF LAKE BONNEVILLE.
In the preceding chapter the features of a single desiccated shore-line are
described; a shore-hne, that is, with nothing above it on the shaping side of
its basin except the varied topography characteristic of dry hind, and noth-
ing below it but the smooth monotony of a lake bottom. Proceeding now
to the consideration of the Bonneville shores, we pass from the simple to the
complex, for the Bonneville Basin is girt by many shore-lines, which form a
continuous series. Only the highest of these is contiguous to land topog-
raphy, and only the lowest encircles an area covered exclusively by lake
sediments. The water has undergone changes of volume wliicli have car-
ried its surface and waves to every part of the basin from the bottom to an
altitude of 1,000 feet. So much of the basin as lies below the highest shore-
line has received lake sediments; and the geologic data comprised in these
sediments are combined with the phenomena of the lower beaches in a man-
ner that is at once instructive and complicated. The superpositions of shore-
line upon lake sediment and lake sediment u])on shore-line record a history
of contracting and expanding lake area, the deciphering of which constitutes
one of the chief subjects of our study. These will be discussed at length in
the sequel. Here it is desired merely to state the foct that for a vertical
space of 1,000 feet on the sides of the liasin, the evidences of lacustrine
waves and lacustrine sedimentation have been iraposeil oii tlic preexistent
cimfiguration of tlie countrv.
Lake Bonneville lay in the district of the Basin Ranges, and the whole
configuration of tlie land al)ove the shore-lines is of the Basin Range \\\>e.
Asdescrilx'd in tlie introductory chapter, that district is studded with a -great
EARLIER SCULPTURE SUBAEKIAL. 91
number of small mountain ranges, standing in irregular order, but with a
nearly constant north-south trend. BetAveen them are narrow valleys Hoored
by detritus worn from their summits during the uncounted ages of their
existence. At the foot of each range, and piled high against its sides, are
great conical heaps of alluvium, each with its apex at a mountain gorge.
At top these alluvial cones are separate, but lower down they adjoin, and
their bases coalesce into a continuous scolloped slope, the visible footstool
of the mountain. The cones, like the valley floors, are composed of detritus
eroded from the mountains, but their material is coarser. At the margins
of the undrained valleys the cones merge by gentle curvature with the
valley floors. In the higher valleys, which drain to the closed basins,
cones from the two sides meet along the medial line, giving to the cross
profile the form of an obtuse \y- Above the alluvial cones all is of solid
rock, and the topographic forms are hard and angular. Every water-pai-ting
is a sharp ridge, and every water-way is an acutely V-shaped gorge.
The ridge and the gorge are characteristic features of land sculpture,
being carved only where rain and running water serve for erosive tools.
The alluvial cone is an equally characteristic land feature, being formed
only where running water throws down detritus, without itself stopping.
They are all the distinctive and exclusive products of land shaping, and
could never originate beneath a lake or ocean.
These are the features exhibited by the Bonneville Basin above the
highest shore-line; and the same features can be traced continuously down-
ward past the shore-line and to the bottoms of the once submerged valleys.
If one stands at a distance and views the side of a valley, lie will see that
each of the great alluvial cones is traceable within the zone of submergence
almost as distinctly and quite as surely as above it. Its curving contour
formed a part of every individual shore of the series. So, too, of the moimt-
ain gorges and ridges; wherever they extend below the ancient water limit
the shore-line can be seen to follow their contours in a manner demonstrat-
ing that they were already in existence when the lines were drawn.
The preexistent topography of the Bonneville Basin was therefore of
terrestrial type and of subaerial origin. The sea-cliff's and embankments
and sediments of the lake were carved from and built on and spread o^•er a
92 LAKE BONNEVILLE.
system of reliefs which originated at a time anterior to the hike, when the
(h-ainao-e of the mountains descended without obstruction to the bottoms
of the valleys. In this respect, and in other respects to be developed further
on, the pi-e-Bonneville conditions were identical with the post-Bonneville.
Illustrations of this general fact could be adduced almost witliout limit,
for they are aifoi'ded by all the slopes of the basin, but a few will suffice.
In Plate VIII there appears at the right a jiortion of the western front
of the Frisco Range. The crowded and uneven contour lines mark the posi-
tion of steep-faced rock undergoing erosion. At the foot of the range is a
system of alluvial cones, represented by contours with smooth curves and
regular spaces. Still lower are the contours produced by wave action, and
lowest of all is the outline of a playa. A moment's attention will show that
the great alluvial cone at a, which, like a trunk glacier, is compounded at
its head of a number of single cones, is represented at the base of the
slope by the convexity at c. The cone h appears, though less plainly, at f;
and the cone d appears at /(. The cone c is greatly disguised at g, being
loaded with a group of embankments; Ijut it is jjrobable that it has liad
something to do with the deflection of shore-currents whereby those em-
bankments were originated. Conversely, the indentation at j represents tlie
uiibroken rock-face at i, where for a space of half a mile no debris-convey-
ing srorffe issues from the mountain; and the dearth of detritus in the remon
A- is represented by the indentation at /. The maj) also suggests, what a
study of the ground demonstrates, that the material built into embankments
was derived by the paring away of the coast to the north f)f each locality of
deposit. Considered by themselves, the monuments of the waves' activity
are by no means inconsiderable; each grou]) of embankments contains
some hundi'eds of millions of cubic yards of gravel; but they sink into insig-
nificance when compared with the stupendous monuments of alluvial activ-
ity on which they rest. They are mere appendages, and the erosion of
their material from the adjacent slopes has by no means oljliterated, though
it lias somewhat defaced, the alluvial forms.
Granite Rock, an isolated mountain of the Salt Lake Desert, has at its
north end a gorge dividing the extremity into two narrow spurs. About
these spurs the Bonneville waters rose to a height several hundred feet
U.S. GEOLOGICAL SUPVET
LAKE BONNEVILLE PL Vm
.luhus BuMi AC..,hil,
Drown bv (• Tb'impttnD
LAND SHAPING BEFORE SHOKE SHAPING. 93
above any alluvial accumulation. All about the .spurs there is a distinct
terrace cut in the granite at the highest water level, and the same can be
traced, less continuously but still unmistakably, along the sides of the
gorge to its head. This relation could not subsist had not the gorge and the
sj)urs been carved out in substantially their pi-esent form before the Avaves
attacked them.
Bradley, speaking of the canyon of Ogden River, says :
It is evident that, when this canyou was originally excavated, the Great Salt Lake
was not far, if at all, above its present level ; so that the rushing torrent which wore out
this old rounded bottom met no check until it had passed entirely beyond the mouth of
thecanyon. There followed a time when the lake tilled nearly or quite to its highest ter-
race; and, meanwhile, the Ogtleii River continued to bring down the sand and pebbles
which it had before been accustomed to sweep out upon the lower terrace, but now,
checke<l by the rising lake, deposited them in the lower parts of its old channel, until
they accumulated to a very high level, not yet accurately located. Again, the lake
retired, and the stream again cut down its channel, sometimes reaching its old level
and sometimes not.'
In each of these localities the subaerial work antecedent to the lake
epoch has greatly exceeded in amount the lacustrine work ; and the last
has in like manner exceeded the subaerial work subsequent to the lake
epoch. Disregarding the rate at which the several processes are carried on,
it is evident that the construction of the alluvial cones of Frisco Mountain
is a greater work than the building of the embankments that ornament their
flanks ; while the preservation of the embankments shows that little alluvial
accumulation has since been made. The carving of the spurs and gorge at
Granite Rock implies the decay and removal of cubic miles of granite, while
the production of the shore terrace involved the excavation of only a few
thousand yards of the same rock.
THE BONNEVIIiLiE SHOKE-IilNE.
The shore-lines of the series in the Bonneville Basin are not of uniform
magnitude. The water rose and fell step by step, but not with equal pace,
and at a few stages it lingered much longer than at others, giving its waves
time to elaborate records of exceptional prominence. One of the excep-
tional records is that which holds the highest position on the slopes ; and to
' U. S. Geol. Surv. of Terr., Ann. Kept, for 1872, p. 196.
94 LAKE BONNEVILLE.
tliis one, par excellenro, tlie name Bonneville has been applied. It marks
tlie greatest, expanse of the ancient lake, and tonus the boundary of the
area of lacnstrine phenomena. .
Above the Bonneville shore-line the whole aspect is that of the dry
land — here, an alternation of acutely cut water partings and water ways;
there, huge, rounded piles of alluvium; the first stream-carved, the last
stream-built; and each presenting to the eye a system of inclined prf)files.
Below the shore-line, the same oblique lines are to be found, but with them
are an abundance of horizontal lines, wrought by the waves at lower levels —
the terraces, beaches, barriers, and embankments of lower shore-lines.
Except in sheltered bays, where the waves had little force, and except
on smooth, mural clifts of rock, where a beach could not cling and where
the waves were impotent for lack of erosive tools, the contrast between wave
work and stream work is strong, and the line separating the two types of
earth-shaping is easily traced. If the Bonneville shore-line were far less
deeply engraved than it is, it would still be conspicuous by reason of its
position. As it is, no geologic insight is necessary to discover it, for it is
one of the pronounced features of the country. It confronts all beholders
and insists on recognition. The tourist who visits Ogden and Salt Lake
City by rail sees it on the Wasatch and on the islands of Great Salt Lake,
and makes note of it as he rides. The farmer who tills the valley below is
familiar with it and knows it A^as made by water; and even the coAV-boy,
finding an easy trail along its terrace as he "rides the range", relieves the
monotony of his existence by hazarding a guess as to its origin.
The altitude of the Bonneville shore-line is about 1,000 feet above Great
Salt Lake and al)Oiit 5,200 feet above the ocean. In defining it as the
highest shore of the basin, I have assumed the correctness of the more
prevalent view of a mooted question ; but before proceeding farther the op-
posing view shovild be considered.
THE QUESTION OF A HIGHER SHORE-LINE.
It has been announced by Peale^ that there is evidence of a Pleistocene
lake in the BonneAalle Basin with a water level from 300 to 600 feet above
the Bonneville shore-line, or from ,''),r)00 to 5,800 feet above the sea. "On
> The AnciuDt Outlet of Great Salt Lake. By A. C. Peale, Am. Jour. Sci., 3d series, vol. 15, 1878,
pp. 439-444.
A DISCREPANCY OF OBSERVATION. 95
both sides of the Portneuf where it comes into Marsh Creek Valley an
upper terrace is seen, and in 1872 Prof. ¥. 11. Bradley also readily identi-
fied an upper terrace in the Marsh Creek Valley at the level of about 1,000
feet above the stream. In Gentile Valley and in Cache Valley also, traces
of this upper terrace exist." In the })assage referred to,^ Bradley mentions
this terrace in connection with stream terraces, but does not speak definitely
of its origin. Its interpretation as a shore feature therefore rests with Peale,
who regards it as identical with the one observed by him "on both sides of
the Pt»rtneuf " It has not been seen by me, but I am by no means sure
that in seeking it I succeeded in following Bradley's route. With more con-
fidence it may be asserted that Marsh Valley is not contoured by any well-
marked shore-line. I was careful to study its slopes from stations at various
levels and under favorable atmospheric conditions, and I failed to discover
even the faintest trace of wave work. The same careful search was made
for high-level shore traces in Cache Valley and Gentile Valley, but none
were found. There are indeed terraces in Gentile Valley, and these are
elsewhere mentioned by Peale, who found their altitudes 5,526, 5,242 and
5,186 feet;^ but they are stream terraces, not shore terraces.
It is with reluctance that I record not only my inability to rediscover
phenomena which another has reported, but also my opinion that his reported
discovery was based on an error of observation ; but the question here in-
volved is of such importance in its relation to the Bonneville history that it
can not well be ignored.
As set forth in the second chapter, there are various other types of ter-
races liable to be mistaken for shore terraces ; and the ranging of shore ter-
races and other wave-wrought features in the same horizontal line, or })lane,
is a characteristic of great imjjortance in their discrimination. To the ob-
server who places himself in that plane and views the distant hillside at his
own level, certain elements of the various shore features appear united in a
horizontal line. If he selects for his observation an hour when the distribu-
tion of lights and shadows gives strong expression to the details of the con-
figuration, he is able to detect a shore record so fjiint that he might cross
and recross it repeatedly without suspecting its existence. Having searched
' Rept. U. S. Geol. Survey Terr, for l>-82, pp. 20a-'203.
^Eept. U. S. Geol. Survey Terr, for 1877, Washington, 1879, p. 001.
96 LAKE BONNEVILLE.
with distant view and selected light for the reported high-level shore traces
in Marsh and ( "ache Valleys, and having failed to discover them, I am satis-
fied that Peale misinterpreted terraces formed in some other Avay.
The matter is not fnlly set forth l)y the recital of the conflicting obser-
vations. T\w Valley of Marsh Creek falls outside not only the Bi)uneville
Hasin l)ut tlic (Jreat Basin. It is di'ained to the great plain of the Snake
River by a deep and rather broad canyon which bears the marks of antitj-
uity. The sides of this canyon, though of crystalline and schistose rf)cks,
are not steep, and at the most constricted point there is a flood-plain a tliou-
sand feet broad. If there was, as Peale supposes, a barrier at this point
containing the ancient lake, then its cutting must have consumed a long
period; and it is incredible that shore terraces have survived the contem-
])oraneous general waste of the surface. If there was no barrier at this point,
then the supposed lake was a great inland sea, flooding the plain of the Snake
River, and its shore tracings on the margins of that plain should have been
much more conspicuous (by reason of the greater magnitude of its waves)
than any drawn in Marsh Valley, — but they have not been discovered.
Moreover, a body of Avater capable of fomaing the supposed shore ter-
races in Marsh Valley would have extended not only to Cache and Gentile
Valleys 1)ut to the Great Salt Lake Desert, and the work of its waves should
be visible, if anywhere, (m the face of the Wasatch Range. In tliat region,
the conditions for the generation of large waves are far more favorable than
in the relatively narroAv valley of Marsh Creek. Nevertheless, a higher line
has not been observed on the margin of the greater basin. Not only has
Peale failed to record it there, but Bradley, Howell, Emmons, Hague, and
King have expressly noted the BonncAnlle as the highest shore-line.^
It may be objected that the failure of these numerous observers to de-
tect an upper shore-line is negative evidence merely, and should be given
little weight in comparison Avith a single positi\'e obser\-ation. But the fail-
ure to detect is in this case something more than a negation. Subaerial land
sculpture is as positive a fact as AvaA-e-Avrought shore sculpture; and the as-
' F. H. Bradle.y, U. S. Geol. Surv. of Terr. Ann. Rept. 1872, p. 192 E. E. Howell, U. S. Geol. Snrv.
West of the 100th Meridian, vol. 3, Geology, p. 2r)0. S. F. Emmons, U. S. Geol. Esplor. -lOth Parallel,
vol. 2, Descriptive Geology, p. 441. Arnold Hague, Idem. pp. 421, 428. Clarence King, U. S. Geol.
Explor. 40th Parallel, vol. 1. Systematic Geology, p. 491.
U. S. GEOLOGICAL SURVEY
LAKE BOXNEJVILLE PLATE IX.
THE GREAT BAR AT
STOCKTON. UTAH.
NEGATIVE EVIDENCE. 97
sertion that the Bonneville is the highest shore-line implies the assertion that
above it the topography is of the ordinary dry land type. Every recogni-
tion of an ancient shore is based, consciously or unconsciously, on an ac-
quaintance with the ordinary cliaracteristics of the features of the land as
well as with the peculiarities of shores; and ability to discriminate the pres-
ence of wave sculpture implies in the same degree ability to note its absence
and its limits. The supremacy of the Bonneville shore has been recognized
not only by many observers Init in a great number of localities, and an induc-
tion resting on so broad a basis may justly demand of a conflicting obser-
vation the most rigorous verification.
K the reader will turn to Plate IX he will be able to realize the weight
of this evidence. The view presents the Bonneville shore at the pass be-
tween Tooele and Rush Valleys. The observer stands on the west side of
the pass and looks eastward toward the Oquirrh Mountains. At the left
lies Tooele Valley, open to the main body of the old lake. At the right is
Rush Valley, which held a sheltered bay. The greatest waves came from
the north, and, beating on the southeast shore of Tooele Bay, carved out a
long line of sea-clififs. The debris was at the same time drifted southward
part of it being built into a free spit 7,000 feet long and 150 feet high at the
extremity, and another part being accumulated during lower stages of the
lake in an immense bay-bar, obstructing the pass. The spit appears in the
picture at the right, following the base of the mountain. The bay-bar
extends from the center of the view to the foreground. It will be observed
that the line of sea-cliff at its most distant point impinges on a spur of the
mountain; and at its southern end, near the middle of the picture, it touches
another spur, while in the interval it crosses only the alluvial slope. There
could scarcely be a greater contrast than between the sculi)turing of the
mountain-spurs above the line of sea-cliffs and the smooth contours of the
slopes below that level. The cliffs are here of rather unusual height, and
the shore emliankments are of exceptional magnitude, so that the separation
between subaqueous and subaerial topography is more than ordinarily dis-
tinct. This fact does not weaken the evidence that the Bonneville shore-line
is the highest, but gives it greater strength. For, if the water had occupied
a higher level in Pleistocene time, the waves would have been able to record
MON I 7
98
LAKE BONNEVILLE.
it at tliis jxtiut l)y a shore-line of unmistakable definition. If shore traces of
a greater lake are anywhere preserved they should lie found at such a point
as this, where the conditions for wave beating are exceptionally favorable.
The same lesson maybe learned fnmi Fiiiun' 21, mikI fnuii tlu* views on
I'lu. "Jl— BuiiiiL'Ville and Intermediate ( nibunknieuts near W, Ilsville, Utah. siinwiUji contrast betueeu Lilturul .iiid
Subaerial Topo*:rapliy.
Plates XXI and XXII, representing the shore topography and mountain
topography at Wellsville and Dove Creek.
MORE ANCIENT LAKES.
Although Peale's supposed discovery is unverified, and though it is
believed that an exhaustive investigation would prove it to be illusory, it is
nevertheless true that some or all of the mountains of the Bonne^^lle Basin
were girt by shore-lines long before the Bonneville epoch, and that if these
shore-lines wei'e extant they would, in some places at least, lie higher than
the Bonneville. The mountains against which Lake BouncA'ille washed are
relatively very old, so old that they were greatly eroded before Tertiary
tiiiie. Ever since their first u})lifting they have been wasted by erosion,
and during at least a portion of the tune the detritus worn from them has
TERTIAKY LAKES OF TDE BONNEVILLE BASIN. 99
been received by the interjacent valleys. The degradation of tlieir crests
and the burial of their bases would long ago have obliterated them had they
not been preserved by a series of supplementary upliftings, which, like the
original, were ditferential, not being shared by the intervening valleys. In
the region of the Great Salt Lake Desert, where a plain has been formed
by the coalescence of many valleys and the local burial of the ranges, the
depth of detritus must be several miles. Of the constitution of this depos-
ited mass nothing is known by direct observation. It is smoothly covered
by the sediments of Lake Bomieville, and no section is exposed. But indi-
rectly we are shown that some ])art of the debris was spread under water,
for the uprising mountain ranges have carried with them here and there,
clinging to their flanks, small patches of lacustrine strata. It is believed
that four separate groups of lake beds have been thus distinguished. The
first of these occurs in the southeastern part of the basin, and probably
touches the shore of the ancient lake only in the estuary of the Sevier
River. No fossils have been found at that point, but there is little reason
to doubt that the strata were once continuous with the Pink Cliff formation,
which covers large areas farther east, and has been classed as early Eocene.
The principal locality of the second is the eastern base of the Ombe Range,
where an isolated outcrop of barren strata resting against the mountain
dips abruptly beneath the later sediments of the desert. These strata have
been correlated on lithologic grounds Avith fossiliferous beds farther west,
and are regarded by the geologists of the Fortieth Parallel Survey as of
Middle Eocene age. The third group, though yielding no fossils, is believed
to be Neocene. It was first noted by Emmons in Rush Valley south of the
Great Salt Lake Desert, and has since been found at the narrows of the
Jordan River, at Salt Lake City, at the north edge of the desert near Matlin,
and at the extreme northwest cornei' of the basin in Cache Valley, whence
it extends across the rim of the basin into Marsh Creek Valley. The strata
of the fourth group, known chiefly from the investigations of King and Hay-
den and their assistants, occur at a number of points along the northern
margin of the plain, and are believed to appear also north of -the divide in
districts now draining to the Snake River. From Morgan Valley to Cache
Valley they occupy a trough between two divisions of the Wasatch Range.
100 LAKE BONNEVILLE.
On the low northward continuation of the main Wasatch ridge, where it
separates Cache and Malade Valleys, they are seen to be wrapped around a
series of low crags of Paleozoic rocks ; and it is evident tliat they liave
been raised to their present prominent position by tlie reliftiug of an ancient
crest. On the east side of it they have been upturned by the displacement
so as to dip at a high angle beneath the Bonneville lacustrine beds of Cache
Valley. On the west they are separated from theii- original continuation
beneath Malade Valley by a fault, the tlirow of which is probably more than
1,000 feet. Their relation to tlie third group has not been established,
and it is possible that they constitute a part of the same series. The local-
ity of the fifth group is just north of Salt Lake City, wliere an epaulette of
Tertiary gravel and sand rests on a jutting shoulder of the Wasatch Range.
This fragment is completely surrounded by faults, its eastern continuation
having been lifted high in air and obliterated by erosion, and its prolonga-
tion in every other direction having been dropped so lo\\- that it is at once
preserved and concealed by the deposits of the plain. This, too, is unfos-
siliferous ; and it is here assigned to the upper Neocene merely on the
strength of its structural relations. It is needless to enter upon these at
this place ; l)ut it should be remarked that the same relations, considered
from another point of view, led King to sunnise its Eocene age.
Each of these lakes made its contribution to the filling of the basin,
receiving, sorting, and spreading the debris from the wasting mountains;
but neither can in strictness be called the predecessor of Lake Bonneville,
for neither was confined to the area of the Pleistocene basin. So far as in-
dicated by observed outcrops, the oldest Eocene lake lay almost entirely
outside the Bonneville area; and it may have existed at a time when the
greater part of that area was dry land. The second stretched westward far
beyond the present drainage of the Salt Lake Desert, and may have over-
lapped the Bonneville Basin but slightly. The third and fourth encroached
northward on the drainage of the Columliia River. Too little is kuowu of
the fifth to indicate its relation to the Bonneville Basin.
Their record is exceedingly fragmentary, but if it were full it would
still give an hnperfect history of the basin in Tertiary time, for there is no
reason to believe that they represent more than a small imrt of that time
NO TERTIARY SHORE-LINES. 101
They tell iis, however, that the physical mutations of the period included
numerous local elevations and depressions, whereby the di'ainage of the
country was repeatedly revolutionized; it was dry land at one time and
and lake basin at another. It is quite possible that the lakes were excep-
tional phenomena, and that the prevailing condition was one in which the
whole area drained to the ocean. It is equally possible that the Bonneville
Basin continuously held a lake which, as the land rose and fell unequally,
was expanded and contracted, now in one direction, now in another.
The character of the lake beds and their relations to the mountains,
show in numerous localities that the ranges were not submerged. Waves
must therefore have beaten on their flanks, and tlie cliffs, terraces, and em-
bankments peculiar to shores must have been wrouglit, but of these there
is no known vestige. When the structure of the mountains has been elabo-
rately studied, so that those elements of their configuration which depend
on the distribution of strata and on faults can be definitely indicated, it may
be possible to point out dissected terraces and ruined sea-clifts as remnants
of Neocene shores; but for the present such vestiges are beyond recognition.
A shore is of the most perishable of geologic phenomena. It is little more
than a congeries of forms ; and whether worn away by atmospheric agencies
or buried by sedimentation, it ceases to lie available as evidence of a water
margin.
OUTLINE OF THE LAKE.
The outline of Lake Bomieville at its highest stage was intrioate. Its
shores presented a succession of promontories and deep bays, and it was
beset with islands. Its longer diameter lay north and south, parallel to the
trend of the mountain ranges of the district and to nearly all the lines of
geologic structure. Its general outline was rudely pear-shaped, with the
stem ])ointing southward. A straggling series of promontories and islands
crossed it near the middle, dividing it into two principal bodies, of which
the northern and Inrger covered the Great Salt Lake Desert, and the south-
ern the Sevier Desert. The long southward bay representing the stem of
the pear, occupied the Escalante Desert. The main body was joined to
the Sevier body by three straits, of which the deepest and broadest lay be-
102 LAKE BONNEVILLE.
tween Simpson Mountain at the east and Mt-Dowell Mountain at the west,
in the r('(i;i()n now known as the Old River Bed. The EscaUinte Bay was
connected with the Sevier body ))y a long strait, most constricted at Tlier-
mos S])ving.
The following details are of local rather than general interest, l)ut are
essential to a full description of the lake. They will be more readily fol-
lowed by the aid of the large map accompanying the volume.
The trend of the ranges gave character to all the major details of the
coast, and the axes of the larger islands, ])eninsulas, and bays lay approxi-
mately north and south. Beginning at the north to describe them, we have
first Cache Valley bay, an oblong sheet of Avater, tangent at one side to the
main l)ody and there joined to it by a broad strait interrupted by several
islands. Inside the bay were three islands, whose positions are now marked
by Franklin, Cache, and Battle Creek buttes. The butte near Smithfield
was likewise an island at first, though finally connected with the land by a bar.
The canyons of Bear, Cub, Logan, and Blacksmith rivers were occupied by
inlets, and the Bear River inlet may have reached at first to Gentile vallcA'.
These were all gradually diminished by the deposits from the sti-eams, and
eventually the Bear River inlet was approximately, and the Logan com-
pletely, filled.
Malade Valley held a long liay running northward from the main bod}',
and having an expansion where the towns of Malade and Samaria now
stand. Parallel but smaller bays occupied the Pocatello and Blue Spring
valleys and the valleys containing Hanzel Spring and the town of Snows-
ville. Park Valley was filled by a bay, exceptional in its east and west
trend, and separated from the main body by a group of islands. The Prom-
ontory range was divided by a strait at the point where it is crossed by the
Central Pacific Railroad, the north j)art being a peninsula and the south a
narrow, rocky island.
Little Mountain, near the town of Corinne, Avas a small island, and the
mountain from which Hanzel Spring issues made a group of islands. There
were three small islands near the site of Kelton, and one just south of Ter-
race. The Ombe range, including Pilot Peak, was an island, sheltering
behind it a bay or sound from wliich a narrow arm ran northward to
DETAILS OF ANCIENT GEOGRAPHY. 103
Thousand Spring Valley, the extreme limit of the water in a northwest
direction.
Of the existing islands of Great Salt Lake, Stansbury and Antelope
were islands then, and Fremont barely showed its apex above water. Of
the "lost mountains" of Great Salt Lake Desert, nearly all overtopped the
flood. Silver Islet, Newfoundland, Terrace Mountain, Lakeside Mountain,
Granite Rock, and a half-dozen nameless buttes, were circled by rocky
and inhospitable coasts, but the Cedar Range west of Skull Valley made a
broad and low island, which, bleak and barren as it now is, we may picture
as then mantled with verdure.
The eastern shore of the main body followed the steep base of the
Wasatch Mountains, and had a simple outline except at three points, Avhere
it was diversified by the estuaries of Box Elder Creek, Ogden River, and
Weber River. The Box Elder estuary extended nearly or quite to the little
mountain valley where the Danish settlement of Mantua lies. Ogden
Canyon was occupied by a long and narrow strait, conuuunicating with a
bay several miles broad, hemmed in by mountains. Through the canyon
of the Weber a similar strait connected the main Ijody of the lake with a
small bay in Morgan valley, — a bay on which the Weber delta gradually
encroached, but wliich was not completely obliterated before the final
subsidence of the water.
The western shore of the main body followed the eastern base of the
Gosiute range, and was characterized by an abundance of small islands. Its
only estuary ran southward a short distance into Deep Creek Valley, stop-
ping several miles north of the settlement.
Southward from the main body ran four long bays, two associated with
the east shore and two with the west. The first of these, counting from the
east, was divided by a close stricture into an outer bay and an inner, the
outer covering the valley of the Jordan River and the inner spreading over
Cedar, Utah, and Goshen valleys and a part of Juab Valley. In the inner
bay the Goshen Hills made two islands, and the Pelican Hills constituted
one large and several small islands. Small estuaries occiipied Emigration
and Little Cottonwood canyons, connecting with the outer bay, and the
inner bay sent an estuary into Provo Canyon. The shalloAV arm in Juab
104 LAKE BONNEVILLE.
Valley was nearl}' closed by one of the Goshen islands. It connected by
the canyon of Salt Creek with the division of the bay in Cjoslien \'al]('y,
and by the j)ass followed by the Utah Southern Eailroad with the l)ay
in Utah Valley.
The second of the southward stretchin<i- liays was similarly constricted,
its outer and ojx'ii jiortion covering Tooele Valley, and its inner, Rush Val-
ley. The two were nearly dissevered by the formation of a wave-liuilt Ijar
at Stockton.
The third bay occiipied White Valley, a barren plain between the Con-
fusion Range and the liigh part of the House Range. Its entrance was ob-
structed by a rocky island consisting of the northern part of the House
Range, and a long, crooked arm extending southward lacked little of com-
municating with a southerly division of the lake and converting the main
part of the House Range into an island.
The fourth bay occupied Snake Valley and was long and shallow, turn-
ing eastward at its southern extremity.
The Confusion Range east of Snake Valley, and the House Range east
of White Valley, were massive peninsulas, joined at their southern extrem-
ities to the western shore of the lake. A corresponding great peninsula on
the east side was constituted by the Oquirrh, Aqui, Simpson, Cherry ("reek,
and Tintic mountains and their dependencies, and had a greater area than
the State of Delaware. These peninsulas, together with the grou]i of islands
lying between them, separated the main body of the lake from tlie SeA'ier
body. The group of islands comprised two of large size and about twenty
of small size. The largest island was ccmstituted by the Dugway Range
and its southward prolongation. Drum Mountain; the second, l)y the
McDowell Mountains.
With the Sevier body were connected two long bays nmning south-
ward and a number of sinaller ones indenting the eastei'u and northeast
ern coast. Of the northern bays, one received the water of Judd Creek
and another that of Cherry Creek. A third, occupying Tintic valley, was
more constricted at the mouth and contained islands. A land-locked bay
received the water of the Sevier RiA'er and was partially tilled by delta
deposits. It was connected with the open lake by a narrow passage through
SIZE OF THE LAKE. 105
the Canyon Range, comparable with the passage of the Hudson through the
Higlilands.
Of the soiTthern bays, the shorter and more open occupied Sevier I^ake
Valley and Preiiss Valley. The longer was narrow and irregular, filling
the valley of Beaver Creek from George's ranch to Minersville, and extend-
ing thence southwestward into the Escalante Desert, where it was shallow.
Its total length was about one hundred miles.
The largest island of the Sevier body was constituted Ijy the Beaver
Range, or Beaver Creek Range, which was separated by a narrow and tor-
tuous strait frc>m a peninsular tract bearing the Frisco and Picacho Mountains.
There were two low islands a few miles broad close to the western shore,
near Antelope Spring. The apex of Fumarole Butte was slightly emergent,
and so was tlie highest point of the contiguous lava naesa. Small islands
marked the sites of Pavant and Kanosh buttes, and there were four rocky
islands near the mouth of Escalante Bay, one of which is now represented
by the more northerly of the Twin Buttes. In Escalante Bay there were five
or six islands.
EXTENT OF THE LAKE,
The area of the Bonneville water surface was 19,750 square miles, a
magnitude ranking it with the Laurentian lakes. A fifth part of this belonged
to the Sevier body with its dependencies, and the remainder to the main
body. Its length, measured in a direct line from Cache Bay to the south end
of Escalante Bay, was 346 miles, and its extreme width, from the mouth of
Spanish Fork Canyon to a point on the Shoshone Range near Dondon Pass,
was 145 miles. If its water surface were given a circular shape, its circum-
ference would be 500 miles, but the actual length of coast, exclusive of isl-
ands, was 2,550 miles. Its maximum depth was about 1,050 feet. The fol-
lowing table will enable the reader to compare these dimensions with the
corresponding dimensions of Great Salt Lake and the Laurentian lakes.'
' The area of Lake Bonneville wa.s me.asured by I. C. Russell ; the areas, lengths, and widths of
the Laurentian lakes, by A. C. Lane. The length of a lake wa.s, for this purpose, defined to be the
length of the longest straight line terminated by two points of the lake shore; its width, the greatest
distance between shores iu a direction at right auglo to the hue of the leugth.
106
LAKE BONNEVILLE.
Tablk I. Dimensions of Lakes.
Bonneville.
Great Salt.
Superior.
Haron.
23, 800
247
215
702
Michigan.
Erie. Ontario.
Area in aqnare milea
19, 750
346
145
1,050
•2. 170
83
51
f49
31.. 500
377
170
1,008
22, 300
330
106
870
9,900
246
58
210
7,250
197
67
738
Width in miles
Extreme depth in feet
* In 1869 ; near high stage. t At high stage.
The greater part of the desiccated bed is an irreclaimaljle desert, liut
its eastern edge is the granary of the Great Basin. The Bear, the Weber,
the Jordan, the Sevier, and other tributaries, fed by the snow-banks of a
score of mountain ranges and plateaus at the east, carry their hfe-giving
moisture to the genial climate of the lowlands, and a belt of oases is the
result. If the water were to rise again to its old mark, more than one hun-
dred towns and villages would be submerged and 120,000 persons would be
di'iven from their homes. The Mormon temple at Salt Lake City would
stand in 850 feet of water, and the temple at Logan, the metropolis of
Cache Valley, would stand in 500 feet of water. Fort Douglas would be
covered to a depth of 150 feet, Ogden 850, Provo 650, Kelton 1,000.
Seven hundi-ed miles of railroad would be immersed, and trans-conti-
nental passengers would be transferred by boat either from Morgan City or
from Spanish Fork to some point near Toano, Nevada, — a voyage of 145
miles for the northern route or 185 miles for the southern. The town of
Fillmore would be half covered, the State House barely remaining on di-y
land, and Mantua, Paradise, Morgan, and Minersville would be lake ports.
Heramon, Bingham, Opliir, Vernon, and Frisco would be peninsular towns ;
and the mining settlements of Drum and Buell would be stranded on islands.
SHORE DETAILS.
The sinuosity of the coast and its diversity of slope and material give
to the shore phenomena the utmost variety. Every typical feature of non-
tidal shores is well illustrated, and some of the combinations are perhaps
unique.
The abundance of salients and reentrants, of promontories and inlets,
has occasioned a large number of spits and bay bars, while long beaches
and liarricrs are rare.
SEA-CLIFFS OF BONNEVILLE SHORE. 107
At an early stage of the investigation, the writer thought that the
coasts facing in certain directions gave evidence of exceptional amounts of
wave work, and imagined that he had discovered therein the record of prev-
alent westerly winds or westerly storms in ancient times. This belief was
dissipated by further study ; and he discovered, as students of modern
shores long ago discovered, that there is a close sympathy between the
magnitude of the shore features and the "fetch" of the efficient waves.
The greater the distance through which waves travel to reach a given coast,
the greater the work accomplished by them. The highest cliffs, the broad-
est terraces, and the largest embankments are those wrought by the unob-
structed waves of the main body ; and opposite coasts appear to have been
equally affected.
The most interesting details of the upper shore-line are found at locali-
ties where similar details affect the lower shore-lines, and it will be conven-
ient to describe them in discussing the order of succession of the shores ;
but certain features should be mentioned here. The greatest sea-cliffs are
as a rule carved from headlands and from the islands of the main body, but
the highest of all occurs in the Jordan Bay at a locality known as the Point
of the Mountain. For a distance of half a mile the cliff there has an aver-
age height of one thousand feet, the eroded material having been swept
to the southwestward and built into a magnificent spit, around the extrem-
ity of which the Utah Southern Railroad winds in passing from Draper to
Lehi. Another notable cliff occurs on the south face of a butte east of Dove
Creek, and is visible from the Central Pacific Railroad between Ombe and
Matlin. The eroded material was in this case swept eastward and north-
ward, being carried about the angle of the butte, then an island, and dis-
tributed in embankments on its eastern face.
The cut-terraces of the Bonneville shore are narrow as compared with
those of one of the lower shore-lines. They rarely exceed a few rods in
width. A good example can be found on the flank of the Wasatch Range
just north of Big Cottonwood Canyon and others on the north end of the
Oquirrh Range near Black Rock. These are mentioned as being easy of
access, but they are less striking than some that are carved on islands at
various points nenr the margin of the Great Salt Lake Desert.
108
LAKE BONXEVJLLE.
Spits are exceedingly nnmermis, being attached to nearly ;ill (if the
ancient islands and to many of tln^ salients of the main coast. < )f tliose
having some magnitude, the most accessible are at Stockton (1*1. IX), near
Grantsville, Tooele Valley (PI. XV), at the Point of the Mountain between
Draper and Lehi, on Kelton Butte near Ombe station, and on the extremi-
ties of the Terrace Mountains.
Fig. 22.— Butt* near Kelton, Utali.
Embankments connecting islands with each other (u- with the main-
land are to be seen at the west end of Park Valley, at Smithfield in
Cache Valley, on Antelope Island in Great Salt Lake, a few miles east of
George's Ranch south oi Deseret, and at the eastern base of the Gosiute
Range.
V-shaped embankments are most numerous in Snake Vallo}-, where no
less than ten occur. Four are attached to tlie Simpson Mountains opposite
to the Old River Bed and others were seen in Preuss Valley and in Beaver
Creek Valley.
THE CUP UF CUP BUTTE. 109
Typical deltas are rare. Certain parts of the valleys of all the }}riiici-
pal streams were occupied by inlets or estuaries, and the heads of these
inlets received alluvial deposits of the nature of deltas; but the process of
accumulation appears usually to have been arrested before the deposit had
extended to the open lake ; and afterward, when the lake receded and the
streams resumed their work of excavation, all but scattered patches of the
alluvium was removed. American Fork, Spanish Fork, and Rock Creek
built free deltas in the Utah Bay, and Spring Creek furnished one to the
shore of Cedar Bay, but these v^ere exceptional and small. At lower levels
great deltas were constructed by many streams, and the deltas of the Bonne-
ville shore ai'e described in connection with these in one of the later sections
of this chapter
Plate VI exhibits a peculiar circular bar observed in a single locality
only. The sketch is in part ideal, for there was no commanding point from
which to obtain the bird's-eye view necessary for the best presentation of the
subject. Near the Old River Bed there is a group of quartzite buttes which
were surrounded by deep water and formed a cluster of rocky islands. To
the north and northwest the deep lake stretched unbroken for more than
one hundred miles, but in all other directions land was near at hand. Each
island butte shows a weather side facing the open water and a lee side fac-
ing land. Each weather side is marked by a sea-cliff, which looks down on
a broad terrace carved from the solid rock. The lee sides have no cliffs,
but are embellished by embankments of various forms, built of the debris
from the weather sides. In the case of the butte figured, the excavation of
the platform was carried so far that only a small remnant of the original
island survived, and a comparatively small additional amount of wave work
would have sufficed to reduce it to a reef. From each margin of the sur-
viving crest, an embankment streams to the leeward, and the two embank-
ments, curving toward each other, unite so as to form a complete oval. At
their point of junction they are a few feet lower than where they leave the
butte. Their material is coarse, ranging up to a diameter of two feet, and
is conspicuously angular, exhibiting none of the rounding characteristic of
detritus that has been rolled long distances upon a beach. Within the oval
rim is a cup 38 feet deep, its sides and lip consisting, on the north, of the
no LAKE BONNEVILLE.
rocky slope of the butte, and elsewhere of the wall of loosely heaped blocks
of quartzite. If the material were volcanic, instead of sedimentary, it would
be easy to imagine the cavity an extinct crater.
Reservoir Butte, another island of the cluster, is figured in PI. XXIV,
and further represented in PI. XXV and in Fig. 3 of PI. VII. It derives
its name from a series of natural cups analogous to the one just described.
These are attached to its steep slopes at various levels, the process of con-
struction having been repeated at as many epochs in the history of the oscil-
lating lake. In this connection, only the cups associated with the highest
shore-line will be described. The longer diameter of the butte trends north
and south. At its northern extremity and along its northwestern face it
displays a bold sea-cliff, from 50 to 100 feet high, springing from a terrace
at the Bonneville level several hundred feet broad. On the eastern side the
cliff and terrace give place near the north end to a massive embankment,
which first swings free from the side of the butte and then curves inward
toward it, meeting it somewhat south of the middle. From the middle of
the western side there starts a similar embankment, which, curving through
an oval arc of 150°, joins the butte at its southern extremity. The interval
between the tei'mini of the two embankments, a space of 1,000 feet along
the southeastern face of the butte, was almost unaffected by the waves,
being neither abraded nor covered by debris. The material contained in
the embankments was derived exclusively from the weather side of the
butte, and though each looped embankment joined the shore at two points,
the conveyance of shore-drift along its crest appears to have been in one
direction only. It is difficult clearly to realize the process of this con-
veyance, but there is no question as to the fact. In one case it left the
shore at a small salient, its course being there tangent to the contour, and,
curving through an arc of 90°, finally assumed a course directly toward the
coast, there almost precipitous. In the other case it left the shore at an
obtuse salient, and before returning swung through so great an arc as nearly
to reverse its direction.
The cups witliin these loops have been somewhat silted u]i in modern
times, but still, except for their diyness, they deserve the name of reser-
voirs. The eastern was found to be 38 feet deep. The embankments were
THE GUPS OF RESEKVOIR BUTTE. HI
built in deep water and upon a foundation inclining steeply from the shore.
Their forms are independent of the configuration of their foundation. They
were not accumulated from the bottom upward, but were constructed by
successive additions at the end, the boulders being rolled along the crest of
the embankment by the breakers and then dropped in deep water at its
extremity. The outer face of the eastern bar has a height above its base of
four hundred feet
EMBANKMENT SERIES.
It might be inferred from the preceding description that the Bonneville
shore-line was the product and is the index of a single uniform and continu-
ous water stage. Indeed, it has been so regarded by every observer who
has published an account of it, and the impression is readily and properly
derived from its ordinary phase. There are, however, a few localities
where the shore mark is distinctly resolvable, and shown to be compounded
of several similar elements at slightly different heights superposed on one
another. One of the most striking localities, and at the same time the one
which first demonstrated the compound nature of the phenomenon, is repre-
resented in PI. X. A rocky cape projecting from the east shore of Snake
Valley sheltered on one side a small bay opening to the south. Across
this bay the waves built a series of bars, as represented in the map. The
outermost of the series, that is, the one farthest from the land, is connected
at its eastern end with a shore cliff labeled on the map " Bonneville Sea-
cliff"; and this cliff runs for some miles southward along the slope of the
valley.
A study of the locality demonstrated beyond question that the excava-
tion occasioning the cliff and its terrace, furnished the material for the bar,
and furthermore, that the same cliff line had previously been connected
with each bar of the series.
It will be readily understood that the inner bar was the first one to be
built, and that the order of position is also the order of age. They stand so
nearly at the same level that no one of them could have been formed in the
rear of another. Their differences of level therefore record changes in the
relation of the water to the land during the period of their formation. If
112 LAKE nONNEVILLE.
we call the inner bar No. 1 and its altitude 11 feet, the series will be repre-
sented by the following list :
Feet.
No. 1 11
No. 2 12
No. 3 13
No. 4 4^
No. 5 4i
Feet.
No. 6 ^
No. 7 8
No. 8 0
No. •) 0
No. 10 18
No importance is to be attached to the individuality of the bars. There
is a rhythm of action in the process of their formation which would prevent
the construction of a continuous and even-topped terrace under the most
uniform conditions. If the bay had been so shallow that the same accu-
mulation of shore drift would have abridged it twice as much, there might
have been twenty bars instead of ten. The first tlu-ee bars signify but a
single epoch, during which the water stood at one level, or perhaps rose
slowly. The next thi-ee, which in point of fact are but obscurely indi\id-
ualized, represent a succeeding water stage eight feet lower and ])ossibl\' of
somewhat greater dm-ation. The seventh bar shows that the next move-
ment consisted of a deepening of the water and was not long sustained.
The eighth and ninth record the lowest stage of all, and the tenth the highest.
The tenth contains so much more material than either of the others, being
founded in deeper water and carried higher, that it must be considered as
representing a longer time, and may be coordinated with either of the ante-
cedent groups.
Outside the tenth bar the plain slopes gently lakeward, being inter-
rupted within the area of the map oidy by a low bar, indicated in the pro-
file. This bar lies so far below the others that, if older, it might not have
interfered with the wave action necessary to their formation. Its relati\e age
therefore does not appear.
The process of construction is clearly demonstrated by the local details.
The sea-cliff was excavated from the alluvial foot slope of a mountain range.
The derived material consisted primarily of boulders, large and small, sand,
and a certain portion of clay. The finer part was immediately washed
lakeward by the undertow. That of middle grade was carried along the
shore to the bay, and the larger boulders remained in situ until sufficiently
U S. GEOLOGICAL SURVEY
LAKE BOHNE'vTLLE PL.X
MAP OF
BAY BARS OF THE BON.XEVILLE SHORE
Near \lw Salt Marsh, in Snake Vallev, Ttah
Bv ^^' D Johnson
JO-ff'€t Contours
Y\% Profile. Vfjiical Sralf t/uef times the Hofizontal .
Julius Bipti 4 Co.Iith
DraifH bu'G Thoinpst
SNAKE VALLEY BAY BARS. 113
reduced by attrition to be transported. In the bay tlie surface currents
^^ere concentrated by converging shores, and a powerful undertow was pro-
duced, whereby a further separation was effected, the shore drift being de-
prived of a coarser grade of debris than that previously eliminated, so that
tlie matter actxially deposited consisted of particles ranging from a lialf inch
to turn- inches in diameter, — a clean shingle without admixture of sand.
The sand and fine gravel thus eliminated by the undertow were deposited
in h)rge part near the liead of the bay, causing the water to shoal rapidly,
and uhimately determining the breaker line to a new position outside the
first, and tlius initiating the construction of a new bar. In this way the
depth and length of the bay were at the same time progressively diminished.
For purposes of comparison the profile of the Snake Valley bars has
been repeated in PI. XI, where a series of .similar phenomena are also drawn
to the same scale. A brief description will be given of each locality.
At the head of Skull Vallev, a few miles north of Government Creek,
there is a low albnial A\'ater-})arting se})arating the valley from the open
desert at the west. At the time of the Bonneville water stage this pass was
reduced to an istlunus only a few rods in width, and the Avater was shallow
on each side. On the Skull Valley side there were formed a series of bay
bars, represented in profile in the plate. The winds under the influence of
which they were formed, covdd have blown only from the northward.
The third profile represents in similar manner a group of bay bars ob-
served a few miles east of Sevier Lake. The general trend of the old shore-
line is there north and south, but at this particular spot there was a small
cove lying on the north side of a rocky promontory. The bars were formed
by northwesterly winds.
The fourth locality is a few miles east of the third, l)eing on the oppo-
site side of the Beaver Creek mountain range near George's Ranch. A
small rocky hill was insulated at high-water stage by a narrow and shallow
strait, and across this strait embankments were eventually built l)y the north-
easterly winds. The first of the embankments, however, did not completely
close the passage, and remains as a spit, while the others are completed
bars. The topographic relations are shown by Fig. 23.
MON I 8
114
LAKE BONNEVILLE.
The locality of tlie fiftli profile is the southwestern an<rle of Tooele Val-
ley, the constructive winds hlmvin^- in this case also fnun the northeast.
.'5\v\
.■^.
?3k
§!, "isi^-^^
Fig. 23. — Bars near George's Ranch, Utah.
The Dove Creek locality is far to the uortli of the others, being on one
of the ancient islands south of Park Valley. Trains of the Central Pacific
Railway pass it midway between Ombe and Matlin; and it falls within the
area represented by PI. XXII. If the reader will turn to that plate, he will
see that the Bonneville shore is represented on the southeastern face of the
island by a sea-cliif and terrace, and on the northeastern by an embankment.
The material for the embankment was derived from the sea-cliff and carried
around the angle by shore action, doubtless by the alternating agency of
winds from diffei'ent directions. Below the Bonneville embankment there is
a fine series of other embankments, which will be described in a later section
of this chapter.
The surface of the island was eroded before the lake epoch, so that its
slopes consist of a series of ridges radiating in all directions. ( )n the south-
east face these were pared away at the Bonneville level, reducing the shore
to a straight cliff; but on tlie northeast face, where the action of the waves
was constructive instead of destructive, the ridges retaiiied their form, and
the embankment was built across from one to another, enclosing a series of
small basins occupied by lagoons. The first and second of these basins are
now about twenty feet deep, ;iud are undrained. The enclosing parapet is
OTHER EMBANKMENT SERIES. 115
a simple bar not susceptible of subdivision, the formative currents appear-
ing to have held a uniform course during its construction. Tlie third basin
is shallower, and a recently-formed drain reveals a section of its parapet,
sliowing it to consist of the three bars indicated in the lowest profile of PI.
XL The current at tliis point nuist have been tln-o\\n fartlier and farther
from tlie land as accumulation'proceeded. The fourth basin is similar to tlie
third, but the fifth lias no inner bar. The low-lying inner liars are obvi-
ously elder than the higli outer l:)ar, and all the minor features of the locality
tend to the conclusion that, during the period of their formation, the train of
shore drift did not extend to the fifth basin. It is inferred by analogy that
there was an antecedent time, within the epoch of the Bonneville shore,
when the shore drift failed to reach the thii'd basin, so that the series of bars
there exhibted is incomplete.
Let us now consider the question why the successively formed bars in
these several localities differ in height. At least three general answers are
possible. The embankments were l)uilt upon the land by means of the
water of the lake, thro-^^'n into motion by the wind, and their variations in
height may have resulted from variations of the wind or of the water or of
the land. It is conceivable that the highest bars were produced by storms
of exceptional force, and the lower by less violent storms. It is conceivable
that the water of the lake rose and fell from time to time, and that the bars
marked successive stages. It is conceivable that the land rose and sank, so
as to bring different horizons successively within reach of the waves; and
finally, it is conceivable that two or more of these causes conspired to pro-
duce the phenomena.
A movement of the land might have been general, involving the entire
basin, or there might have been differential movements, changing the rela-
tive height at various points. In the first case the lake would be carried
up and down with its basin, and there would be no change in the relation
of shore and water. The oidy land movement therefore which could pro-
duce the phenomena, is one of a differential nature, and this would of neces-
sity give rise to dissimilar results at widely separated places. If the sev-
eral bar series are harmonious in their vertical relations, it is safe to say
that they do not indicate oscillations of land.
116 LAKE BONNKVILLB.
A movement of the water surface would evidently produce clian<i-cs of
the same vertical amount at every point, so that the hypothesis of lake os-
cillation would be negatived if the several systems of ditterentiated bars
were found to be inharmonious.
The remaining hypothesis of imequal storm force may take two foi-ms.
In the first place, it might be imagined that each indi\ndual embankment of
exceptional height was the creature of a single storm, or of a limited series
of storms ; or, in the second place, it is conceivable that the general char-
acter of the weather underwent secular variations ; so that from century t(j
century there were notable changes in the maximum force of storm winds.
Under the first view, Ave should anticipate that localities dominated by
Avinds from different directions Avould not accord in the character of their
bar systems; the approximate coincidence of exceptional storms from oppo-
site directions, being only adA^entitious, could not be expected to recin- with
uniformity. Under the second A-icAv, on the contrary, there Avould be uni-
foiTtiitA' of result, — a general change of climate affecting all localities alike.
The eolian hypothesis Avould therefore be disproved neither liy the har-
mony nor by the lack of harmony of the obserA'ed results. It admits,
hoAvever, of an independent test of crucial vahie. Great AvaA-es are unques-
tionably able to transfer coarser shore drift than small Avaves, so that Avhere
the supply of debris is heterogeneous, the character of that selected for the
construction of embankments is an index of the poAver of the AvaA^es. If,
therefore, in localities Avhere the shore drift is derived from the luisorted
allnvium, it be found that the higher bars contain coarser fragments than the
lower, it is i)roper to infer that they oAve their superior height to superiority
of Avave force; l)iit if it be found that all the bars of a series are uniform in
composition, their inequalities of size cannot be referred to variations of
storm force, either local or general.
As a matter of fact, there is no correlation of coarse material Avitli high
bars. The Snake Valley series Avas scrutinized Avitli reference to this point
and found to be uniform in conq)osition. We may then cease to consider
the Avind, at least so far as the more iinjiortaht A-ariations are concerned, and
limit attention to the hypotheses ot land nioxcmcnt and lake iiio\ cineiit.
The theory of laud moA-ement Avould be sustaineil 1>\' a discordanci' among
I :, s, (;i':iii.oi:li..\l. suiA'KY
REPOHT Oyr LAKE BONNEVlLIjE. J 'J, ATE XI
HYPOTHESES AND TESTS. 1 1 7
the systems of bars. The theory of lake movement would be sustained by
an accordance. An imperfect accordance miglit indicate a combination of
the land and lake changes.
The facts are assembled in PI. XI, to which the reader is again referred.
Each of the profiles represents a section at right angles to the system of
bars it illustrates, and all are dra\\u to the same scale, the vertical element
being exaggerated three-fold. They are grouped on the page in such man-
ner that the outer embankments of the several series appear at the right and
fall in the same vertical column.
The first consideration affecting the comparison is that each series pre-
sumably represents the same period of time, so that, if a correlation is pos-
sible, the embankment drawn at the right in one series should correspond
to that at the right in the others. That at the extreme left in one should
correspond to that at the extreme left in tne others, and the intermediate
portions should be comparable. The only exception to that rule is in the
case of the Dove Creek series, which, as already explained, may represent
only the later portion of the time consumed in the formation of the others.
Restricting attention to the first five groups of bars, we note first that
the right-hand member of each is higher than any other. The second con-
spicuous fact is that the member second in size stands at the extreme left.
To this there is a single unimportant exception, which vanishes if we con-
sider the three bars at the left of the upper profile to constitute a single
member comparable with the individual bars of the other series. It is by
no means improbable that a more careful stud}' of the Skull Valley locality
would resolve the left-hand maximum into such a series as was found in
Snake Valley.
The most extended series exhibits a third maximum, lower than either
of the others, but intermediate in position and standing somewhat to the
right of the middle of the profile. No other profile shows a third maximum,
but three of them exhibit bars of approximately the same height, which may
be conceived to represent it, if the bars of the second minimum are assumed
to have been covered and concealed by the great outer bar. It is easy to
understand that a condensed or foreshortened series would exhibit super-
ficially only the maxima of a fully extended series. It therefore seems
118 LAKE BONNEVILLE.
proper to correlate the intermediate maximum of the upper profile with the
bar appearing at the inner base of the outer niaxiiiuiin in tlie second, tliinl,
and foui'th profiles. In the fiftli profile, bars representing tlie fii-st mi id third
maxima stand in juxtaposition; and it is necessary to assume tluit tlic inter-
vening maximum, as well as the two minima, is covered and concealed.
It thus appears that, in their most general features, the groups of bars
are in accordance, with no greater variation than might readily be ascriljed
to local disparity of condition.
The difference between the altitude of the outer bar and that of the
intermediate maximum was measured in tour localities. In Snake Valley
it is 10 feet, in Skull Valley 12 feet, in Sevier Lake Valley 15.3 feet, and
at George's Ranch 15 feet. The range of these measurements is 5 feet, and
this must be regarded as a real discrej^ancy, though not a gi-eat one.
The altitude of the outer bar above the inner maximum was measured
at five points and found to be 5 feet, 10 feet, 10 feet, 7 feet, 8 feet, — the
enumeration following the order of the diagrams. Here again the range
is 5 feet.
If the inner bar be compared with the intermediate maximum instead
of with the outer bar, the diff"erences are found to be 5 ft, 2.7 ft., 5.3 ft., and
8 ft., showing again a range of 5 feet.
Finally, the low bars observed between the inner and intermediate
maxima have approximately the same relation in tlie tln-ee localities where
they were observed. Compared witli the intermediate maximum, their
measured difi"erences ai'e 3.5 ft, 2.3 ft. and 4.7 ft., tlie nuige being 2^ ft.
These com])arisons exhaust the data, and they appear to establish the
systematic hannony of the phenomena. It is inconceivable that such ac-
cord shoidd be fortuitous. The most complete record (that in which the
bar system was spread out most broadly, so as to resolve it most completely
into its elements) exhibits three maxima with intermediiitc miiiim;i. Tlie
record second in extent shows the three maxima and one miniiiimii, — the
other minimum being overplaced and concciilcd. Tlie Sevier Lake ri'cord
shows the same four elements, but more compactly arranged. At George's
Ranch the three maxima are so closely crowded that l)oth minima are con-
cealed. At the head of Tooele Vallev, the outer and inner maxima are in
ADJUSTMENT BY LEAST SQUARES. 119
juxtaposition and all the intermediate elements ot" the series are buried.
The ordinary bay bar, in which all the elements are welded together and
covered by the last and highest deposit, is logically the final term of the
series of facts.
The hypothesis of water movement is therefore sustained. The chang-
ing relations of land and water during the formation of that complex record
to which we have applied the title of the Bonneville shore-line, were brought
about by the alternate rising and falling of the water surface. While the
higher bars were being formed, there was more water in the basin; while the
lower, less.
Having thus established the correlation of the series of profiles by a
comparison of the unmodified facts of observation, it is now proper to adjust
them to one another for the purpose of ascertaining the mean (juantitative
value of changes of water level. Applying the method of least squares, we
obtain for the most probable values of the water stages, referred to the low-
est of the series as zero and arranged in the order of time:*
feet.
First maximum 12.3 ± .2
First minimuin 3.0 ± .2
Second m.axiinum 7,3 i .2
Second minininm 0.0
Third maximum 20.1 ± .2
Adjusted to the same zero, the observations at the several localities ex-
hibit the following relations:
Table II. Embankment Series of the Boiinei^Ule Shore-line.
Locality.
Allilnile in feet.
Variation fioDi ailjusfoil mean.
1st
Max.
1st
Miu.
2.1
Max.
2a
Min.
3ll
Mas.
lat
Max
Iflt
Min
2il
Max
2.1
Mm
ad
Max
Snake V.illey
Skull Valley
Sevier Lake Valley.
George's Ranch
Tooele Valley
in.o
10. .■!
12 2
13.0
12.2
4.5
5.3
2. 2
8 0
7.6
C.9
5.fi
0.0
18.0
20.3
22. 2
20.6
20.2
+ .7
—2.0
— .1
+ 1.3
— .1
+ .6
+ 1.4
-1.7
+ .7
+ .3
— .4
-1.7
—2.1
+ .2
+ 2.1
+ .5
+ •1
1
' The computation incliuled data from the Dove Creek protile aud from tho PruiiiiB Valley bars.
It was performed by Mr. A. L. Webster.
120 LAKE BONNEVILLE.
The residual discordance, as shown by the cohimns at the nght, is not
large, thougli it is somewhat greater than the range ot" variation found in the
longitudinal profile of the crest of a single har. A part of it is i)n)b;il)lv due
to inaccuracies of measurement; no instrinnents of j)recision were emj)loyed,
and the methods at more than one locality were improvised and crude. There
will be no impro})riety in referring the remainhig part to exceptional storms
combined with local conditions.
Reverting now to the Dove Creek series, wliicli the field observations
gave reason to suspect of incomj)leteness, we find by inspection that its two
levels can readily be correlated with the second and third maxima of the gen-
eralized profile. It is highly probable, therefore, that the earlier water
stages, including the first maximum and the first minimum, failed to make
an independent record at that ])lace.
To convert the data fully into terms of lake history it is necessary to
comjiare the epochs of formation of the several l:)ars in the matter of
duration as well as in that of water stage. The amount of shore di'ift
accumulated in the several bars has to be considered, and likewise the
manner in which the varying water stage affected the rate of accunudation.
A determination of absolute duration is manifestly out of the (piestion,
and any estimate of relative duration is largely a matter of indi\ddual judg-
ment.
An attempt has been made in Fig. G of PI. XI to represent the oscilla-
tions and their periods in a quantitative way, so far as they are dediu-ible
from the plienomena. If the facts permitted xis to draw the full curve of
oscillation with all its details it would unquestionably be far less simple.
The number of minima concealed by the bars of even the most extended
series may be very great; and it is even possible that these bars do not re})-
resent a continuous history. If, after the series had been ])artly formed, the
lake shrank to nuich smaller dimensions, returning to the region of the Bon-
neville shore only after a long interval, there seems no wav to determine
this fact by the phenomena of tlie shore. Probablv tlie only conclusions
deducible from the profiles are; first, that, when the lake basin was full, the
position of the water level was unstable; and, second, that of a series of
high-water stages, the latest was the highest of all.
INTERPRETATION OP V-HARS. 121
It will perhaps occur to the reader that the enumeration and discussion
of these facts have been needlessly prolix; and this I am not prepared to
deny. But it may be said in extenuation that the phenomena belong;- to a
novel tvpe, and that the method of investigation Avas so far new that the
simple conclusions finally reached required for their establishment a full
presentation of the alternative hyj^otheses eliminated by the investigation.
In the sequel it will appear that even these simple conclusions afford a key
to the understanding of some of the most important elements in the history
of the lake, and through that history are brought into relation to the prob-
lem oi' the physical condition of the earth's interior.
One result of tlie discovery and interpretation of the groups of bay
bars of the Bonneville shore-line was the explanation of certain features of
the V-embankments which had previously been problematic. V-embank-
ments have already been described as triangular terraces built against mount-
ain slopes at the shore level, and margined toward the lake by even-topped
parapets. In the light of the conclusions thus detailed it becomes evident
that this conformation was occasioned by oscillations of the lake during the
period of the formation of the terrace. The space within the parapet is
usually occupied by a playa, the surface of which is from five to eight feet
below the enclosing rim. This represents a certain amount of silting up of
the basin. If there were no filling, it cannot be doubted that the interior
of each enclosure would exhibit a series of bars parallel to one or both arms
of the jiarapet, and corresponding in height and arrangement to the bay bars.
In fact, this very phenomenon was finally observed at several localities.
The most interesting are in Preuss Valley along the western base of the
Frisco Mountains. In that valle}' the shore features of many different hor-
izons afforded an instructive study, and were carefully mapped. PI. VIII
gives a general view of the phenomena on the east side of the valley, and
it will be noted that the Bonneville shore-line includes three of these tri-
angular terraces. The same appear on a somewhat larger scale in Pis.
XVI, XVII, and XVIII. The parapet associated with the middle group of
embankments (PI. XVII) offers an exception to the general rule, in that it
is broken through by the drainage, so that the interior contains no playa.
It contains instead the eroded remnants of a system of bars parallel to the
122 LAKE BONNEVILLE.
southern pai-apet. In this system it is easy to recognize the equivalents of
first and second maxima of the Snake Valley bars, holding their j^roper re-
lation to the para])et, which corresponds to the third or outer maximum.
The V-enibankment of the south group, PI. XVIII, is undi-ained, but its
filling has not progressed so far as to obliterate the inner maximum. Two
elements of the bay-bar series are therefore represented ; and the same were
found in the north group of embankments.
In the case of the middle and southern of these Preuss Valley embank-
ments, and in two f)r three other instances, the interior embankments are
parallel to one parapet only, so as to constitute with that a series of parallel
ridges connecting the remaining parapet with the shore. It seems evident
that in these cases the growth of the triangular terrace was chiefly or en-
tirely by additions to a single face; and it may not be improper to define
the aggregate structure as a spit gradually projected into the lake by recur-
rent storms from a certain direction and buttressed by successively formed
bay bars connecting its extremity at various stages with other points of the
shore, the bay bars being the work of a series of storms from a diff'erenr
direction.
The variety of contour assumed by the parapets of the V-erabank-
ments, and by the crests of the hooks and loops with which they are more
or less affiliated, is illustrated by PI. VII.
DETERMINATION OF STILL WATER LEVEL.
One of the collateral results of the composite nature of the Bonne-
ville shore-line is a discrepancy in the evidence aft'orded by different parts
of the shore phenomena as to tlie altitude of the ancient water level. Tliose
parts of the coast which were given their character by excavation indicate
the water level by a line forming the angle between a cliff above and a ter-
race below, and this line often represents the lowest of the series of water
levels recorded by the bay bars. Tlie im])ression made by the waves at the
last and highest level is usually, thougli not always, so faint that it has been
obliterated by the falling down of the cliff. On the other hand, those parts
of the shore formed by the accunuilation of detritus appear as a rule at the
highest water stage only. The localities in which embankments represent-
U S.GEOLOGIC^AL S'JRlrEy
JjAI-'vE BOiJN'B'.lr.bE PL. xn
42°'-
41'
40'
39°
38°
US'
!uliu9 Bien * Co, lilK
MAP OF
E BONNEVILLE
I'lIKSKNT UYliRdllRAFMIC DIVISIONS
OF THE
BONXE\TLLE BASIN
n red )
and
The areas with alUUide
ijreater than 7000 feet.
cin "blice ;
\'n[c The dotted lines indicate dottbi
42
41°
SCA LE : t
Dt;i«Ti tfv C Thuiopsi
FINDING TUE STILL WATER LEVEL. 123
ing progressive action are differentiated, are exceptional ; and in ordinary-
cases the latest additional material covers all the preceding. For an accu-
rate determination of the height of the niaxiinnni water level, it is therefore
necessary to consider the character of the record to which measurement is
aj)plied. The base of a sea-cliff is apt to give too low an indication, while
the crest line of an embankment is not.
If this element were the only one to 'be taken into accoimt, it would be
a simple matter to ascertain in every region, by using emljankments only,
the precise height of the old water level; but there is unfortunately a com-
plication. The crest of a completed embankment always stands somewhat
higher than the still water level of the lake to which it pertains ; and the
amount of the difference depends on conditions which are not entirely sim-
ple. They include some elements of the configuration of the bottom, and
especially the magnitude of the largest incident waves. The same elements
of configuration affect also the record embodied in the base line of a cliff,
but the magnitude of the waves does not. On a coast foeing deep water
the base of the sea-cliffs coincides very closely with the still water level.
If, therefore, the surface of Lake Bonneville had not fluctuated while near
its highest stage, the sea-clifis would aft'ord a more intelligible record of its
precise horizon than the embankments.
As the case stands, the best indications are sometimes afforded by one
class of facts and sometimes by the other. Wherever it is evident that the
sea-cliffs associated \\ ith the maxinuun water stage survive, their base is
assumed to give the most authentic record. Where these cannot be dis-
criminated, embankments have been em])loyed, an allowance being made
for their height above the water line. This allowance is a matter of judg-
ment in each individual case.
It will be instructive to illustrate the difficulties of the subject by a few
examples.
If the reader will refer to the general map of the lake, he will see that
the Jordan valley was occupied ]>y a large bay receiving waves from the
open lake, while the Utah Lake valley was occupied by a land-locked bay
affected by no waves but those generated within its own borders. These
two bays were joined by a narrow strait at the locality now known as the
124 LAKE BONNEVILLE.
Point of the Mountain, and from the coast east of tliis strait tliere was con-
structed an iniiiiense triaiij^'uhir terrace, receiving upon one side the (h'tritus
rolled by the great waves of the Jordan Bay, and on the other the slioic drift
moved by the snitdler waves of the inner bay.
The parapets on the two margins of the V-shaped embankment give
clear expression to this disparity of conditions. Tliat facing Jordan Bay is
the more massive and tlie longer, and the other is Iniilt against it as a sort
of appendage. The general altitude of the larger bar is six feet greater than
that of the less; and since the latter has all the features of a completed endjank-
raent rising above the water level, it follows that the northern or higher eni-
bankiuent was built more tlian six feet above the still water level of the lake.
Kelton Butte (Fig. 22) projected its apex as a small island above the
water level and was surrounded by deep water. From one direction it re-
ceived waves propagated through a distance of thirty miles, and by these a
cliff and terrace were carved out and an embankment was constructed. The
terrace is itself tei-raced in such way as to encoiu-age the belief that the base
of the cliff corresponds Avith the highest water stage; but this base is 7i feet
lower than the contiguous embankment.
At a locality in Preuss Valley, where the conditions did not admit of
the generation of waves of great size, an embankment has lieen connected
by leveling with a sea-cliff and terrace, and found to be 5 feet higher than
the terrace. In this case part of the discrepancy is doubtless referable to
the failure of the waves at the highest stage to score a durable record on
the face of the sea-cliff" carved at a lower level.
A similar measurement was made at Wellsville in Cache Valley, where
also the waves were not of the greatest magnitude, and gave a difference of
19 feet. At the opposite end of Cache Valley, near the town of Franklin,
tliere is a small indentation in the shore in which an isolated embankment
has been preserved with a crest 12 feet above the base of the adjacent sea-
cliff; and in a sheltered spot north of the town of Tecoma, in the northwest-
ern portion of the Ijasin, the measurement of similar details showed a differ-
ence of 20 feet.
The state of preservation of the embankments is all that could be de-
sired for purposes of measurement. The innjority of them are composed of
DEPTH OF THE OLD LAKE. 125
gravel, and are exempted by their ridge-like form from the destructive action
of cross-flowing drainage. A few inches at most would express the loss their
crests have sustained from the wash of the rain. With tlie sea-cliffs and
wave-cut terraces it is different. The decay of a cliff' throws (lo\\n a con-
stantly increasing amount of del)ris, which falls to the base ;ui(l foi-ins a
talus; and every little drainage channel by which a cliff' is divided spreads-a
heap of alluvium upon the terrace below. The base of the cliff, therefore —
the element of the jirofile which for purposes of measurement it is most
desiral:)le to recognize — has been almost universally covered by the rising
alluvium, so that its precise position is a matter of estimation or indirect
observation.
The discovery that the old Avater line is no longer of uniform height,
and the tact that its variations of altitude afford a means of measuring the
recent differential movements of the earth's crust within the basin, give occa-
sion for great regret that the exact identification of the highest water stage
is so difficult a matter. In a majority of instances the range of uncertainty,
after all allowances have been made, amounts to five or six feet.
DEPTH.
The greatest depth of the lake was about 1,050 feet; and this depth
obtained over all the western ])art of the present site of Great Salt Lake.
The })oint west of Antelope Island, where the deepest water in Great Salt
Lake is now found, did not sustain the same relation to Lake Bonneville,
))ut was rivaled and perhaps sur})assed l)y jioints between Promontory
and the Terrace mountains. The Great Salt Lake Desert has now a re-
markably flat floor, and the ancient de])th of water above it did not vary
greatly in diflerent parts. The mean de])th of the main body of L'lke Bon-
neville was in the neighborhood of 800 feet. The Sevier body had a max-
imum depth of G50 feet, and Esciilante bay of about UO feet.
THE MAP.
The mapping of the Bonneville shore received careful attention; audit
is pro])alde that the extent and fonn of no modern lake in an unsettled
country is more accurately known. The determination of certain questions
126 LAKE BONNEVILLK.
with reference to overflow necessituted tlie inspection (if a lariic part of the
periphery; and the knowledge thus obtained ol' tlic position of tlic coast was
afterwards systematically supplemented until a complete ma]) Wecame possi-
ble. T\u' insulai- mountains standing- on Oreat Salt Lake Desert were not
visited, and the coast lines about their sides were for the most part deduced
from the contours of the published maps of the Survey of the Fortieth
Parallel; but with this exception all of the coast was seen by some member
of the corps and sketched from actual observation. A large pai-t of it was
examined by more than one individual. The map is indebted to Mr. C4il-
bert Thompson for tlu^ details of the west coast between Deep ('reek and
Montello, and for the bays at the north ends of Pocatello and Malade \'al-
leys. He delineated also the details west of Sevier Lake and in the southern
extension of White Valley. The map is indebted to j\Ir. Thompson and Mr.
Albert L. Webster for the outlines of the Escalante Bay. Mr. Willard I).
Johnson delineated the shores of the White Valley Bay and the coasts on
the Dugway, MacDowell, and Simpson Mountains. The outline in Tintic
Valley was furnished by Mr. H. A. Wheeler. Mr. Israel C. Russell map])ed
the bay east of the Canyon Range, and is responsible for most of the coast
between Fillmore and George's Ranch. He contributed also numerous de-
tails in all parts of the basin. The remaining portions of the shore were
mapped by me. Some idea of the distribution of responsibility for the maj),
as well as of the thoroughness of the exploration, may be derived from an
examination of PI. Ill, where the routes of travel are exhibited.
THE PROA^O SIIORE-I^INE.
Below the Bonneville shore-line are numerous other shore-lines, amting
which one is cons})icuous. The name Provo was given to it on account of
a great delta, which is at once a notable feature of the shore-line and a prom-
inent element of the topograj)hy of Utah N'alley in the vicinity of the town
of Provo. The shore mark so far surpasses in strength all others of the
series that this character serves for its identification; and it has been recog-
nized in all parts of the basin without the necessity either of tracing its
meander or of measuring its altitude. It has indeed been recognized with
confidence des})ite conflicting determinations of altitude, for it is neither
THE PROVO SHORE-LINE. 127
uniform in height nor uniform in its vertical relation to the Bonneville shore-
line. In a general way it is 375 feet lower than the Bonneville shore and
625 feet higher tlian the water of Great Salt Lake.
The Provo record is more recent than the Bonneville. "^I'liis a])pears,
first, from its state of preservation; tlie Provo cliffs are the steeper and
sharper and the smaller talus lies at their base. It appears, second, from
the absence of lake sediments on the surfaces of the Provo terraces. Dur-
ing the formation of the Bonneville shore, the horizon of tlie Provo was
sufficiently submerged to receive a layer of fine sediment; and a lake de-
posit commensurate in amount with the shore drift accumulated in the Bon-
neville embankments would not escape detection if it had rested on the
terraces of the Provo shore. The relative age is shown also Ijy the relation
of the shores to the outlet of the lake, as will be explained in another
chapter.
The duration of the water stage recorded by the Provo shore was
greater than that of the Bonneville water stage. Although tlie Bonneville
is the most conspicuous of all the shore-lines, it does not exhibit the greatest
monuments of wave work, but owes its prominence largely to its position
at the top of the series, where it is contrasted with topographic features of
another type. There are several other shore-lines which rival it, and, al-
though it probably outranks in magnitude all except the Provo, its discrim-
ination would be a difficult matter were it an intermediate member of the
series. The Provo, on the contrary, is rendered conspicuous chiefly by the
magnitude of its phenomena. Its embankments are the most massive, and
its wave-cut terraces are the broadest. Moreover, the Provo Lake was in
every way inferior to the Bonneville as a field for the generation of jiowerful
waves. It was narrower and shallower and obstructed by larger islands.
To have constructed shores eciual to those of the Bomieville, it must needs
have existed a longer time; and still longer to have built its greater struct-
urcis.
OUTLINE AND EXTENT.
The outline of the lower shore was the less tortuous. The sinuosity of
the Bonneville shore is due to the fact tliat the water flooded a large num-
ber of the narrow trouglis of the Great Basin and was partially divided by
128 LAKE BONNEVILLE.
the mountain ridges. When the Avater retreated to tlic I'rovo level, it ;il);iii-
doned a considerable number of the valleys and retired on in;iii\ jiarts of
the coast from the uneven mountain faces to the smooth contours of the
alluvial slopes. Two of the largest bays, the Escalante and the Snake Val-
ley, were completely desiccated, and so was a third part of the Sevier Des-
ert. The water was withdrawn from Thousand Spring and Buell Valleys,
from Gi'ouse Valley and Park Valley, from Ogden Valley and Morgan
Valley, from Cedar Valley, Rush Valley, and Tintic Valley, and from both
ends of Juab Valley. Of the three straits joining the Sevier Ixtdy with tlie
main body of the lake, only the eastern remained. The closhig of the cen-
tral and western straits joined to the western peninsula the islands Avhicli ha<l
been constituted by the MacDowell and Dugway Mountains. The islands
formed Ijy the Promontory, the Cedar, and the Beaver Creek Ranges, were
converted into peninsulas, and so was Pilot Peak. The grouj) of islands
south of Park Valley and the group south of Cuidew were joined to the niiiin-
land; and it is possible that the islands constituted by the Lakeside Mountains
were united to the Cedar Mountain peninsula. Doubtless many other hills
that had previously been submerged now a})peared as islands ; but none of
these were of great extent, and the total numljer of islands must have been
greatly diminished. Ann)ng the emergent islands were some of the volcanic
buttes west of the town of I^illmore and a basaltic mesa southwest of
the town of Deseret. The passage from Cache Valley to the main body
was reduced to a narrow strait only a few hundred feet in width, and the
entrances to the Utah Lake bay and the White Valley bay were greatly
restricted.
SHORE CHARACTERS.
Li several respects the newer shore-line has a different facies tVoni tiie
older. It has already been remarked that it is more freshly cut. It is char
acterized also by its l)i-oader terraces, by its deltas, \)y its tufas, and liy a
peculiar duplication in its ])rofile.
While the Provo cut-terraces are far broader than the Bonneville, the
associated sea-cliffs are not so high, the difference being occasioned, in part
at least, by the relations of the two water surfaces to the general slojjc. If a
•J S. GEOLOGICAL SURVEY
LAKE BONNEVILLE, PL-Xffl.
42
^^L.
39'
38'
113°
112'
nx°
-■i 4a'
H41=
112 "
MAT OF
nONXKN'lLLi;
XTRNT AT rili; UATK
oJ'the
'ROVO SHOP.EI.INK
IVovo vs'alor :vrea iii blue
I I I I Miles.
HI'
38°
JuUiw Uipii Atu.Iilh
Diaira byti Thompsc
TIIK PliOVO TERRACES.
129
profile \k' drawn across any of the valleys occupied by the lake, it will be
found to be broadly U-shaped. "^I'he Hoor of each valley is nearly flat ; and
the alluvial slopes at tlie sides, rising- very gently at first, gradually in-
crease their inclination until they join tlie acclivities of the mountains. The
Bonneville and Provo shores are so related to the valleys that their differ-
ence of a few hundred feet of altitude corresponds to a general and notable
difference in the slopes of the land at their margins. The Provo waves,
attacking comparatively gentle slopes, produced terraces of great width,
as the companions of cliffs with but moderate height. Floors 200 to 400
feet broad are of frequent occurrence ; and in one place a cliff 75 feet high
overlooks a terrace 750 feet wide.
FiG. 24. — Limt'stoui} buttu uear lie ddiny; Spriug, Giv.at Salt Lake Desert ; au island at the Provo stage.
Deitas.-The abundance of deltas on the Provo coast requires for its ex-
planation a considerable chapter of the history of the lake. It has already
been remarked that the principal streams tributary to the basin rise at
the east. In flowing westward each of them encounters one or more
mountain ranges, across which it passes in a deep and narrow defile or can-
yon. The drainage system is older than the lake; and this series of canyons
was completed Ijy the streams before the Bonneville epoch, so as to form
MON I ^9
130 LAKE BONNEVILLK.
]);irt of tlie system of valleys flooded ])y tin; lake. When the water first
rose to the Bonneville level, it set back a number of miles into each of the
canyons; and in some instances extended beyond the first mountiuu i-inge,
forming small bays on the eastern side. During the period represented by
the Bonneville shore-line, the detritus brought by the rivers Avas tlu-ovvn into
these bays and inlets and gradually reduced their dimensions. A few of
the smaller inlets were completely filled; and in three or four instances
small deltas were projected into the lake; but the remainder of the canyons
retained the character of inlets until the water fell. At the beginning of the
Provo epoch it is probable that nearly all of the larger canyons admitted
short estuaries, but of this there is no definite record. If such existed, they
were quickly filled by alluvium, — the preexisting accumulations at the heads
of the canyons aff'ording an abundant supply ready at hand. The fomia-
tion of a delta in the open lake must have begun at the mouth of each can-
yon soon after the establislmient of the water stage; and it was continued
until the close of the Provo epoch. The water surface then fell once more,
and the lowering of the mouths of the streams caused them to begin the
erosion of the deltas ; but the broad terraces built on the open plain were
not so easily effaced as the alluvial dejjosits within the narrow canyons, and
the destiiictive activity of the streams has accomplished oid}- the opening
of teiTaced channels through them.
The channeling of the deltas was accompanied by the construction of
other deltas at lower levels, so that each river course is margined by a series
of deltas embodying a portion of the history of the progressive changes of
the lake. In the discussion of these series in a later section, the several
deltas of the Provo shore will receive separate mention and description.
Calcareous tufa has been found in association with many of the shore-
lines and was }jrobably deposited in some amount at all stages of the lake.
It is exceptionally abundant at the Provo level, but it will be more con-
venient to describe its occurrence in a special section devoted to the subject
of tufa.
The Underscore.- Where tlic Provo watcr mark is a work of excavation, its
characteristic profile includes two sea-cliffs and two terraces. The upper
cliff is the greater of the two, and the terrace at its foot is the broader ter-
THE UNDEKSCORK. 131
race. The lower terrace is rarely more than a twentieth part as great as
the upper, and in many places it could not be detected. The vertical space
between the two shelves is estimated to range from five to twenty feet; at
the sole point of measurement it is six feet. The main terrace is conspicu-
ously distinguished by its flatness. At no other stage of the lake have the
waves carved out so level a platform. In its broader examples the lake-
ward slope is barely perceptible to the eye; and at no i)oint does the total
descent from the foot of the upper cliff to the crest of the lower exceed five
feet. The lower terrace has no idiosyncrasies aside from its association with
the upper, but that peculiai'ity has caused it to be styled in the field note-
books "the underscore," and it will be convenient to retain the designation.
Though not iiniversally discernible, yet it is so persistent a feature as to be
found serviceable in the identification of the Provo shore at doubtful points.
EMBANKMENT SERIES.
Wliere the water mark consists of works of construction its characters
are less constant. As a rule, the bays of the Provo coast are spanned by
single bars; and its spits, like those of the Bonneville shore, are apparently
simple in structure; but in a few instances the accumulations in bays are
observed to consist of two bars with the outer lower than the inner. The
difference of height was never subjected to measurement; but was estimated
to be about fifteen feet. At Dove Creek (see PI. XXII) the shore exhibits
two wave-built terraces, of which the outer and later formed is 14 feet lower
than the inner.
On Terrace Mountain, a few miles south of Ombe station, the Provo em-
bankments in a small bay are separated after the manner of the Bonneville
embankments in Snake Valley, and include six distinct bars with a faint
suggestion of four others. A profile of these is given in Fig. 3 of PI. XIV.
Fig. 1 of the same plate exhibits the cut terrace with the underscore; Fig. 2,
the double bay bar.
In Tooele Valley the Provo presents the most remarkable expansion
of a shore record that has anywhere been preserved. During that epoch the
valley contained an open bay receiving storm waves from the broadest por-
tion of the lake. The principal excavation was from the alluvial slopes of
132 LAKE BONNEVILLE.
the western base of the 0<iuirrli mtmntaiiis, ;nul tlic material was swept
soutliward to th(! shaUow head of the bay, where it was built into a series of
bars stretcliiny from sliore to shore witli sweeping curves. In this series 65
inihvichial bars have been counted and their aggi-egate width is more than a
mile. Their order of position is necessarily the order of their formation;
and their i)rofile (PI. XIV, Fig. 4) exhibits in consecutive order the local
variations of the relation of water to land during- the Provo epoch.
The double terraces, the double bay bars, the bar series of Terrace
Mountain, and the bar series of Tooele Valley, constitute the ^\'liole of our
information with regard to the oscillations of the lake during the Provo epoch ;
and all effort to coi-relate them and deduce a consistent history has failed,
lu the discussion of the Bonneville })rofiles, it was found that the more
extended series was represented in the less extended only by its highest
members, the minima of the profiles disappearing as they were condensed.
If the same relation subsists between the Provo profiles, then each member
of the Terrace Mountain series should be foiuid to coi-respond to some max-
imum of the Tooele Valley series. The comparison is necessarily begini Ijy
equating the highest member of one locality Avitli the highest member of the
other: — that is, by saying that the Terrace Mountain r and d are equivalent
to the Tooele Valley C and D. Tlien a and h of the Terrace profile should be
represented by maxima to the left of C in the Tooele ])rofile; but the only
maximum of this kind is at A, and is too low by nearly 30 feet. The ter-
race from E to F may be compared without gi-eat incongruity with the bar
e; but the maximum at H is 20 feet too high to be represented by the bar
/ Similar difficulties prevent the correlation of the Ten-ace profile with the
double bar, Fig. 2; but they do not arise when the latter is compared with
the Tooele profile. The higher bar of the pair may fairly be taken as the
equivalent of the Tooele group from A to F, and the lower bar may represent
the emljankments from G to I.
The wave-cut terrace and underscore (Fig. 1) have no sj-mpathy with
any bar gronj) except the simple pair. It is ]n-obable that the greater and
higher bar K was in whole or part the contemporary of the terrace M ; and
it is possi])le that the minor bar L was the contemporary of the underscore.
Though the wave-cut terraces and the Tooele Valley bar series sever-
PROBLEMS OF CORRELATION. 133
ally accord with the double bars, tliey do not harmonize with each other.
Upon the assumption that each records the oscillations of the water-surface,
the deduced histories are different. The exceptional flatness and extreme
breadth of the upper terrace seem to show that the waves were for a long
time at a unifomi horizon, or else that the latest work of excavation was at
so low a level that all terraces of anterior production were undercut and
obliterated ; the underscore appears to re})resent a brief lingering after the
main terrace had been finally dried. The Tooele Valley profile, on the
other hand, indicates a gradual rise of 40 feet from the base of the bar A to
the upper teiTace B, followed, first, by a tolerably uniform high stage BF,
and, second, by a stage GI ten or fifteen feet lower. If the breadth of the
bars be taken as a time scale, the liigher stage had twice the duration of the
lower, but occupied somewhat less time than the gradual rise preceding it.
If the production of an individual bar be taken as the unit for time-scale,
the higlier stage had two and one-half times the duration of the succeeding
low stage and tlu-ee times the duration of the antecedent rise. If, now, we
correlate the central group of Tooele bars with the main wave-cut terrace,
and correlate the outer group of bars with the underscore, we find two diffi-
culties. In the first place, the underscore represents but a small fraction of
the period of wave action under consideration, while the outer series of
Tooele bars, upon any plausible basis of estimate, represents a relatively large
fraction. In the second place, the progressive rise implied by the Tooele
profile has no expression in the wave-cut terraces, where its effect would be
to impair the definition of the outer edge of the main terrace and contra-
vene its characteristic flatness. There appears then no way in which to
reconcile the various analytic naanifestations of the Provo shore on the hy-
pothesis that the recorded oscillations are purely those of the water surface.
The presumption is therefore in favor of the alternative hypothesis that
there were differential movements of the earth's crust witliin the basin dui'-
ing this epoch. Unfortunately, the data are too meager for the discussion
of this hypothesis.
134 Lake bonne villb.
THE MAP.
During the prosecution of the field work, no attempt was made to ob-
tain the data necessary for mapping the Provo shore-Hne ; hut the note-
books contain so many incidental references to its position that it has been
found possible to construct a map not grossly eiToneous. The reader is
warned that the outline delineated in PI. XIII is approximate only. A
similar qualification applies to estimates of area. The water surface at the
Provo stage had an approximate extent of 13,000 square miles, 11,500 be-
longing to the main body and 1,500 to the Sevier body.
THE STANSBURY SHORE-LINE.
From the Provo water line to the margin of Great Salt Lake, the de-
scent is more than 600 feet. From the same line to the Bonneville shore
the ascent is less than 400 feet. In the upper space all the conspicuous
lacustrine features are referable to shore action, but there are subordinate
evidences of sedimentation. In the lower space lake sediments predominate,
giving their peculiar smoothness to the surface, and the shore tracings are
relatively unimportant. Upon any jjrofile a considerable number of shores
can be recognized below the Px'ovo; and it is probable that a system of
levelings would enable these to be correlated in a consistent system. This
has not been done, and only a single one has been widely recognized. That
one is distinguished merely by the greater magnitude of its cliffs and em-
bankments, but is not sufficiently accented to be everywhere identified. It
is called the Stansbury shore-line. Its strongest delineation is upon Stans-
bury Island, where owing to local conditions it rivals the Provo shore in
definition and surpasses the Bonneville. In abundance of tufaceous deposit
it probably ranks next to the Provo,
Its height was measured at two points only. On the west side of the
Terrace Range it lies 310 feet below the Provo shore; and at the north end
of the Aqui Range 346 feet. At the latter locality it was found to be 330 feet
above the level of Great Salt Lake. It is thus seen to divide about equally
the interspace betwen the Provo shore and the shore of Great Salt Lake.
At the time of its formation the maximum depth of the lake was only
about half as great as at the Provo date ; and the water surface was corre-
Li S. GEOLOGICAL SUF.VEY
Ii/vI<E BONNEVILLE PL. X'/
MAP OF
SHORE KMljANKMKNTS,
Near Gi-aiilsvilli- . llali
Hv II A WhiMli
Fig. Pruiilc, .-1 A' B
A
BoTin^yiiLe.
.;}^^-T^^
?
mm
^
I^
ip^^i^
3v^-o
-^^liiA^
S
-^
Veriical Scale tivice the MoTizontcil
Julius Bi<;n ^Co.lilK
Drawn by G Thumpei,
STANSBUEY SHOEE-LINB. 135
spondingly diminished. The constructive waves were therefore less power-
ful and the time necessary for the performance of an equal work was longer.
There is good evidence, however, that the period of time represented by this
shore is shorter than that represented by the Provo. The body of water
covering the Se^-ier Desert during the Provo epoch was smaller than the
body occupying the Great Salt Lake Desert at the Stansbury epoch ; and
yet the shore phenomena by which it is outlined are upon a far larger scale
than any exhibited l)y the Stansbury.
The water was at this time withdrawn from the Sevier Desert, but cov-
ered the main portion of the Great Salt Lake Desert. It washed the foot
of the Wasatch and extended within a few miles of the western line of the
Bonneville shore, but was excluded from most of the bays at the north and
south. Its total area was in the neighborhood of 7,000 square miles.
THE INTERMEDIATE SHORE-IjINES.
In every locality where the Bonneville and Provo shores are marked
by considerable accumulations of shore drift, the whole of the intermediate
slope is similarly characterized. In every locality where the Bonneville
and Provo shores give evidence of excavation, the intervening space is com-
pletely occu})ied by similar evidence, but the phenomena are in this case
less conspicuous.
DESCRIPTION OF EMBANKMENTS.
Grantsviiie.-If the reader will turn to PI. XV, which represents a tract of
country a few miles south of the town of Grantsville, he will see that an
angle of the valley, containing a bay of the ancient lake, occasioned the
local accumulation of large embankments. By studying the contours of
the map, or by referring to the accompanying profile, he will see that these
embankments have their crests at various levels, the order of height being
also the order of horizontal position. The Provo embankment was can-ied
entirely across the bay, so as to complete a bar; and the same is true of the
one next to it in the series. The development of the other embankments
was arrested while they were yet spits. Box Elder Creek, which was tribu-
136 LAKE liONNEVILLE.
tary to the bay, has its modern course deflected by the spits, and has opened
a passage through the bay bars. Each of these enibankuients is tlie product
of essentially the same comV)ination of local conthtions. At each of the
represented stages the shore drift derived from a long alluvial slope at the
north, beyond the field of the map, was carried southward toward the edge
of the bay and there accumulated in a long embanlcment, built in the deep
water of the bay on a line tangent to the shore at the north. Between the
Bonneville and the Provo there are four principal embankments; and it was
a natural assumption, made at an early stage of the investigation, tliat each
of these embankments recorded the work accomplished by the waves at a
stage represented by the height of its ci'est. This assumption was for a
time unquestioned, but later developments led to doubt of its validity; and,
in order to test it, a systematic collection of shore data was undertaken.
Localities were sought where the configuration of the lake bottom favored
the construction of shore embankments at all levels from the Bonneville to
the Provo, and at such localities contour maps Avere made and profiles were
measured with the spirit-level. By means of these maps and profiles, taken
in connection with the details of structure observed at the same locality, the
general history of the Intermediate shore-lines was developed, but the orig-
inal assumption was overthrown.
In order to present this liistory to the reader, with the evidence upon
which it rests, it will be necessary to make him acquainted with a selected
series of the maps, which series has been reproduced in the accompanying
plates.
preuss vaiiey.-Pl. VIII rcpreseuts eight miles of the eastern side of Preuss
Valley. At the right stand the rocky spurs of the Frisco Mountains, and
against their base the stream drift from the canyons is piled in great alluvial
cones. While the lake occupied the valley, the fi)rm of its shore was given
by the contours of the alluvium, each great cone occasioning a rovmded
cape, and each interval between the cones, a bay. From tlnee of the capes
the currents were deflected in such way as to accunudate the shore drift in
a system of embankments, — and this at all levels from the Bonneville to the
Provo. Pis. XVI, XVII and XVIII show the details of the thi-ee localities
of accumulation.
U S. GEOLOGICAL SURVEY
LAKE BONNEVILLE PLXVI
MAP OF THE
NORTH GROUP
OF
SHORE emuankment;
IN
PREUSS VALLEY, UTAH.
By C;. K. Uilberl.
1000 2000
10- feet 0?Titours -
;^_::.^.i^'^:?^*^
VIEW AS SEEN FROM THE SOUTH
.Jul.ua Bii-i. Jt ti.liOi
Drawn bv C Thoropsi
U S. GEOLOGICAL SURVEY
uAflE BONNEVILLE PL X\'n
MAP OF THE
MIDDLK ('MOW
SlIORK EMIJAXKMKXTS.
PHKl'SS VAr.LKV. r'L\JI
Bv (J K (iillxTt
iOOO
SCALE bB=
10 CO
I
FEET
lO/Wl liinU'UiK
BonneMllr
hill 1 rrofiLc u.s seen from t hi: South
rerllitil \til/r id'llhir Ihf Hi'ii/.oil In I
Ulujs IJi(Mi ftCo.hUi
Di :(wu W li Tliuuiliinn
U S. GEOLOGICAL SURVEY
LAKE BONNE'-ILLE PLJ^'in
MAP OF THE
sorrii (iRoiip
OF
S II 0 K K E MBAXKM EN T S ,
PREUSS VALLEY, UTAH,
Bv (; K Gilbert
iOOO o
SCALE f ^ ^ ^ -^ ^
1000 £000
— ! FEET
JO - /ef/ (o n / o u rs-
Pi'oiile as seen ti-oni (he .Kouth
Tertnuil Saxl^ <loubh the Bonxonttd ,
.luliua Rien & l.o.hOi
Drawn bvG Tlioinps
Embankments of the intermediate shore-lines. 137
The snowpiow.-A siiTiilar compound embankment, but on a grander scale,
was formed at the southern opening of the strait joining the two principal
bodies of the lake. Its general relations appear on 1*1. XXXI and its de-
tails on PI. XIX. The shore drift in this case came from the east, being
derived from a great alluvial slope formed by the coalescence of many-
cones from the Simpson Mountains. The embankments into which it was
built are characterized by the V-form, and are so jjiled one upon another as
to have suggested the name Snowplow, by which the group was distin-
guished in the field notes.
Stockton and Weiisviiie.-The embankmeuts at Stockton (PI. XX) are of a dif-
ferent type, having lieen tlu'own across a strait and not merely projected
from a shore. That of the Bonneville stage is, however, exceptional, run-
ning athwart the others in the form of a broad spit ; and those of the Prove
stage, which fall without the field of the map on the south side, are typical
bay bars. A perspective view of the field of this map is given in PI. IX,
and a profile of the contiguous Provo bay bars in PI. XIV. The embank-
ments at Wells^^lle in Cache Valley (PI. XXI) are of the same type as those
near Grantsville, but are less perfectly preserved. A mountain stream flow-
ing across them has opened a wide channel ; and the exti'emities of two em-
baidiments have been truncated by land slides.
Dove creek.-A group of cmbaukinents near Dove Creek, represented in
PI. XXII, is somewhat similar to the Snowplow, but the material was in
large part torn by the waves from solid rock, and not merely dug from
alluvium. It first traveled northward along the coast from which it was
cut ; and then turning abruptly to the northwest, was built into terraces
upon another face of the same island.
COMPARISON OF EMBANKMENTS.
For the purpose of comparison, the vertical elements of all these local-
ities have been assembled on a single page in PI. XXIII. The data are so
diverse in character that they are not easily comjjared by means of profiles
on a natural scale, and an attempt has therefore been made to eliminate all
accessory features and represent merely altitudes and quantities of wave
work. In each of the profiles of the plate, a sti'aight line inclined at 45° is
138 LAKE BONNEVILLE.
made to stand for the original surface upon which the embankments were
built. The horizontal distance of each point of eacli profile from this base
represents the total quantity of material added to the shore at that locality
and level. In the case of the Stockton diagram, Fig. 6, it was impossil^le to
represent comparative quantities of material, and only altitudes are ex-
pressed. At the north end of Preuss Valley the lower members were not
mapped, because they lay at an inconvenient distance from the upper ; and
the profile, Fig. 3, is thei-efore incomplete. The profile is additionally ex-
ceptional in that it is doubled, to represent two series of embaiLkments dif-
fering in date of fonnation. The earlier series is (h-awn at the left, and the
later, which in part overlies it, at the right. Fig. 5 represents a profile
measured at Cup Butte, five miles northwest of the Snowplow. In this case
the vertical element only is valuable for comparison, because the upper and
lower portions of the slope were not similarly disposed with reference to the
waves. The lower received no deposit, but exhibits the rock of the butte
carved in terraces and cliffs. Fig. 10 represents the gi-eat embankment at
the Point of the Mountain south of Salt Lake City.
The vertical measurements for the profile in Fig. 7 were made by means
of two mercurial barometers, one of which was read at shoi*t intervals at a
station near by, while the other was carried from point to point. At Cup
Butte, Fig. .5, the measurement was by means of a hand-level attached to a
Jacob's staff", the unit of the instrument having been detennined experiment-
ally by comparison with the surveyor's level. The remaining profiles were
measured with a s})irit-level.
The profiles are an-anged upon the page in the order of geographic
position. The three groups in Preuss Valley fall within a radius of tlu-ee
miles. The Snowplow and Cup Butte groups are 100 miles farther north
but are separated from each other by five miles only. The Grantsville
and Stockton groups are 10 miles apart and are 45 miles north of the
Snowplow. The Wellsville and Dove Creek groups are isolated. They
are 80 miles apart and each is 90 miles distant from Grantsville, the nearest
of the other localities. The Point of the Mountain is separated from the
Stockton group by an interval of more than 20 miles, including a mountain
range.
U S. GEOLOGICAL SURVEY
U\KE BONNEVlLLi; FL.XK
W \\\, v,\\\„\\
MAP OF
[1-: SNOWPLOW,
A
1M)1' SlIOHK THUIUCKS
near tliP
KD.l'TAH.
SCALE t
lO-fefi Contours
VIEW FROM THE NORTHWEST.
luliiis ilu-ii \ i'o.lllll
Dr.n*i, bv li Th"iup>nn
U S. GEOLOGICAL SURVEY
LAKE BONNEVILLE PZyj^
MAP OF THE PASS
bPiwHon
RUSH AND TOOELE VALLEYS. ULUl.
ShoM-ind the
NViVVE HUILT B.UJRIER
Rv H A VVhoelei-
aOOO Q 100 0 2O00
SCALE III I I CCCT
l/6> -fegl. Contott.rs .
\>Ttiral Spctio n from O" to H u s li L n Ke
VeftfitiL Scale tionbJe (fie //orixontul
* ISicn S.Co,lia,
Qrowu by GTIiompHOn
S.GEOLGOICAL oLIRVr-'i
LAI-LE BoMNE-.OLLE PL 773
VIEW FROM THE EAST
^^^^te.^
-lulius Ripn A Cu.i.tJ,
wn by C.Tli..inpson and W H.Holtn
U S-GEOLOOrcAL SUPirEY
LAKE BONNEVILLE PLXSH
MAP OF
SHORE TERRACES
NeaT Dove Ci'cpk, Ulnh
Bv Gilbert Thoinpsim
SCALE °
1000
I —
2U00
'•^'••■■^'^\
/O/eel t'imlniirs
Boitri^, , II f
'■ N\\\SvVVAvy-
VIEW FFfOM Th'e" s'ouf H EAS'f'" " ■
- , , ^ ^> \\^\>.v\%<-
liliurt tlii-n A Co. Ml,
Drawn bv li Tli.>iri
ATTEMPTS AT CORRELATION. 139
Having thus assembled the data, let us now endeavor to obtain a clear
conception of the questions to be answered by their comparison. At the
Grantsville locality the shore di-ift is built into a small number of large,
definite, individual embankments, differing in height. The analogy of the
Bonneville and Provo shores suggests the hypothesis that each of these em-
bankments was produced by, and therefore represents, a prolonged mainte-
nance of the water surface at a corresponding height. Under this hypothesis
there should have been accmuulated at each of the other localities during
this time a corresponding embankment; and if all the embankments remain
undisturbed in their original position, a complete correlation should readily
be made out. For each of the principal embankments at Grantsville there
should be found a representative at the same height in each of the other
localities. If such correspondence is not found, it is necessary either to
abandon the hypothesis, or else to supplement it by the assumption that the
relations of the embankments were deranged by differential movements of
the earth's crust occurring during the general period of their formation.
Examining now another locality, as, for example, the Wellsville, Fig. 8,
we find that, although it exhibits a small number of large individual em-
bankments, the altitudes of these do not correspond each to each with the
altitudes of the Grantsville embankments. However the comparison is made
this disparity appears. In the plate the Bonneville horizon is assumed as the
common zero for the vertical elements of the profiles. This assumption is
purely arbitrary, and Avas not adhered to in making the comparisons. In
order to test the matter fully, each group of embankments was represented
on a sheet of transparent paper by a system of parallel lines whose intervals
were drawn to a scale, so as to agree with the vertical intervals of the em-
bankments. These transparent sheets were then superposed in pairs and
other combinations, and were tentatively adjusted in numerous ways, in the
hope of discovering occult correspondences.
Only one element of order was discovered. A horizon from 15 to 25
feet below the Bonneville (marked a on the plate) is discernible in eight of
the ten localities. With this single exception, there are no correspondences
which can not be referred to fortuitous coincidence. Not only is the series
of altitudes different at each locality, but the number of embankments varies
140 LAKE BONNEVILLE.
from place to place. It is evident, therefore, that the hypothesis of persistent
water stages is tenable only with the addition of a h}"]iothesis of contempf)-
raneoxis dis})lacement; and the question arises whether we have any means
of subjecting- this phase of it to test.
HYPOTHESIS OF DIFFERENTIAL DISPLACEMENT.
The supplementary hypothesis is not a priori a violent one. As will be
set forth in a following chapter, our investigation has fully demonstrated tlmt
the Bonneville shore-line is no longer of equal altitude at all points, but varies
within the region comprising these localities through a range of more than
100 feet. The same has been shown with reference to the Provo shore-line;
and it has also been shown that a part of the Bonneville derangement oc-
curred before the Provo epoch. In the series of localities represented by
the profiles, the interval between the Bonneville and Provo shore-lines ranges
from 345 feet to 400 feet, exhibiting a difference of 55 feet. It is therefore
easy to believe that the localities may have undergone relative displacement
after the construction of certain of the Intennediate embankments and prior
to the construction of others, or even that local changes of water level may
have been thus occasioned at one locality while the process of shore forma-
tion was continuous at another. The possibility of confusion thus intro-
duced seems at first unlimited, and a rigorous test of the hjqiothesis would
be difficult were it not for a fortunate circumstance. The .surveyed locali-
ties include several pairs, the members of which are so closely associated
geographically that there is a strong presumption against their ha\'ing been
affected discordantly by contemporaneous earth movements. The middle
and southern localities of Preuss Valley, Figs. 1 and 2, are but two miles
apart, and bear the same relation to the adjacent mountain rnnge. Tlie
localities of the Old River Bed, Figs. 4 and 5, are five miles apart, and those
of Tooele Valley, Figs. 6 and 7, about ten miles apart.
The principal recent displacements of the basin have been of the nature
of broad, gentle undidations, not aft'ecting the horizontality of the shore-lines,
so far as that is distinguishable by the eye. The region including each
gi'ou]) of localities may properly be assumed to have risen or fallen in con-
sequence of such earth movements without important internal change;
ATTEMPTS TO EXPLAIN DISCOKDANCB. 141
and this circumstance leads us to anticipate that the members of each of
these groups of embankment localities will be found to correspond with each
other better than with the members of other groups or with isolated locali-
ties.
This expectation is realized in the relation of the Bonneville and Provo
sliores. In each of the two Preuss Valley localities tlie Bonneville-Provo
interval is 345 feet. At the two localities of the Ohl River Bed it is 400
feet and 398 feet. At the two localities of Tooele Valley it is 375 feet and
378 feet. At the Point of the mountain, 20 miles east of Tooele Valley, it
is 375 feet. When, however, the Intermediate shores are considered, no cor-
relation is found.
The harmonious relations exhibited by the Bonneville and Provo shore-
lines at contiguous localities confirm the postulate that a general correlation
should be possible in these localities, desjiite the influence of contempora-
neous displacement, and compels us to reject displacement as a sufficient
explanation of the discordance of the Intermediate shore-lines.
By these considerations, and by others which it is unnecessary to de-
tail, the writer was led to abandon the hypothesis of persistent water stages,
even though a better was not immediately suggested. Eventually another
was found, and this is believed to give a satisfactory explanation of the phe-
nomena. It may be called the hypothesis of an oscillating water surface.
HYPOTHESIS OF OSCILLATING WATER SURFACE.
In order to set foi-th this hypothesis, it will be necessary to recur to
the general theory of the construction of shore emljankments, page 46,
and imagine how the process would be modified by the contemporane-
ous oscillation of the water surface. Let us select some point of the coast
where the local conditions determine the deposition of shore drift, and
assume that a spit has been formed, its crest being slightly higher than the
surface of the water when still. Suppose now that the height of the water
surface is gradually increased. A portion or the whole of the shore drift
contriljuted by the next stonn is deposited upon the top of the embankment,
tending to restore the profile to its normal relation with the still-water level.
During this restoration the growth of the end of the spit is retarded, or per-
142 LAKE BONNEVILLE.
lia])s altogether checked. If the general rise of the water is very slow, the
construction of the embankment keeps pace with it, and the crest maintains
its nonnal height, but if the rise of water is more rapid, the spit is sooner or
later submerged, so that the stonn waves sweep over it. Witli a slight sub-
mergence, the course of the shore cuiTent is unchanged, and the waves still
break as they reach the line of the spit, so that the conditions of littoral
transportation are not there abrogated. A portion of the force of the waves
is expended on the land inside the spit, but the shore di-ift is not diverted or
divided so long as the position of the shore current remains luichanged.
The growth of the spit therefore continues in its submerged condition, and
if the water level ceases to rise, the crest of the spit eventually emerges and
acquires its normal height.
Assume now that the rise of the lake surface, being more rapid than
the growth of the spit, does not cease, but continues indefinitely. A time
must sooner or later be reached when the depth of water on the submerged
spit permits the waves to pass over it ahnost unimpeded, and at the same
time penults the shore cm-rent to be deflected inward. The formation of a
new spit then begins in a position higher on the sloping side of the basin.
Now let the tendency of the water level be reversed, so that it gradu-
ally falls. Additions will continue to be made to the new spit by the ac-
cumulation of shore di-ift on its weather face and at its end ; but sooner
or later the water will reach a stage at which the shore current will be de-
flected by the lower-lying spit, and at Avhicli the waves in sweeping over
that spit will be broken and diminished in force. Additions to the upper
spit will then cease, and the growth of the lower spit will be renewed.
If this theory is well founded, there should be produced at the margin
of an oscillating lake a series of embankments separated by vertical inter-
vals bearing some relation to the magnitude of the waves, and each of these
should grow in height every time the oscillating water surface passes its
horizon, either in ascending or in descending. The rate of growth would
naturally be diff'erent at different points on the margin of the lake ; and the
interval between embankments, being a function of wave magnitude, should
vary in different regions, being greatest where cu'cumstances are most favor-
able for the development of waves.
THEORY OF OSCILLATING WATER SURFACE. 143
This relation between the embankment interval and the local conditions
affecting wave" magnitude is so evident a consequence of the theory that it
may be used to test its applicability to the problem in question, and this
may be further tested by considering the phenomena of littoral excavation
in connection with those of littoral construction. The conditions which
theoretically produce a rhythm in the process of littoral deposition have
no similar effect upon the concomitant erosion. In the regions of littoral
erosion, the shore currents are not deflected by circumstances associated
with the rise and fall of the water level, and the zone subjected to the
beating of the waves bears always the same relation to the still water level.
An equable rise of the water should therefore pare away the coast in an
equable manner; and upon the theory of rhythmic deposition, the Inter-
mediate embankments should not be associated with sea-cliff's and cut-
ten-aces of comparable magnitude.
Proceeding now to the application of the hypothesis to the problem in
question, we may premise that the water level has twice risen above the
Provo horizon and afterward descended, one rise extending to the Bonne-
ville shore-line and the other being nearly as great. The space occupied by
the Intermediate embankments has thus been subjected to wave action at
least fom- times. These oscillations have been demonstrated by independ-
ent evidence; and it is pi'obable that there were also numerous minor oscil-
lations. The conditions were therefore favorable for the production of the
rhj'tluuic result.
The vertical interspaces between the Intermediate embankments yield
evidence confirmatory of the hypothesis. Six of the localities represented
in the profiles and maps are suitable for comparison. Among these the local
conditions indicate the greatest waves at Grantsville and Dove Creek, and at
these points the average interspaces between the principal embankments
are 72 feet and 75 feet. The conditions are less favorable at Wellsville and
the Snowplow, but it is doubtful which of these two localities should rank
next At Wells\alle the average interspace is 60 feet. At the Snowplow it
is either 71 feet or 61 feet, according as an embankment of doubtful rank is
included or excluded. In Preuss Valley, where there was comparatively
small scope for the formation of waves, the average interspace is 53 feet.
144 LAKE BONNEVILLE.
Eqiuvlly liariiionious i« tlio evidence from the iilieiioniena of littoral
excavation. Take, for example, the Siiowplow. The material there aggre-
gated was derived from a broad alluvial slope, partly represented in the
northern portion of tlie map (PI. XIX). In this region there is a nearly
continuous slope from the Provo terrace to the Bonneville terrace; and
above the Boinieville cliff there is a continuous slope of undisturbed allu-
vium. This latter originally extended over the entire slope, including and
beyond the Provo horizon, and it can be restored in imagination so as to
realize the magnitude of the excavation. From ten to thirty feet ai)}Xiar to
have been removed from the general surface, and this so evenly that there
are only one or two points where the presence of sea-cliffs can be indicated;
and even these -can not readily be traced to corresponding embankments.
The same is true in i\ general way of all localities. Not oidy are the In-
termediate embankments nowhere connected \vith a s)'stem c)f differentiated
cliffs and ten-aces, but it lias been found impossible, (wherever the attemjjt
has lieen made,) to trace their horizons fairly into the region of excavation.
At the Snowplow locality, the excavated alluvium is of such nature as to be
easily modified by the rain and it does not preserve the minor details of the
configixration im])ressed on it by the waves; but elsewhere, on alluvial
slopes of coarser material, the inters])ace between the Bonneville and Provo
cut-terraces has been observed to be occupied by a continuous s}'stem of
naiTow terraces and cliffs, constituting a sort of horizontal striation of the
surface. At one point, near Pilot Peak, thirty-three separate teiTaces were
counted, the average interspace being less than ten feet.
The liy})othesis receives additional support from the structui-e of the
individual embankments. The spit built by the waves of a lake with a con-
stant level should normally have a certain simplicity of structm'e, the prin-
cipal additions to its mass being made at the distal end, and the deposits
near the crest having no irregularity, except that referable to the disjjarity,
in force and dij'ection, of the constructive storms. A spit consti'ucted by
the waves of an oscillating water surface should theoretically be begun at
a relatively low level and receive additions in the form of superposed
spits of various altitudes and lengths, some extending to the end of the mole
and others sto2)ping short. The compound structure is characteristic of the
ACCESSORY EVIDENCE.
145
Intermediate embankments. Sectional exposures are indeed rarely to be
seen; but from many of the embankments there project, either at the distal
extremity or on the shoreward side, shelves or spurs indicating the horizons
of the lower wave work and testif}'ing to the composite structure of the mass.
Fig. 25 gives an illustration of this, observed near Willow S2)ring, west
of the Great Salt Lake Desert. A broad spit is characterized by a hook at
its extremity. A study of its details shows that the shore di-ift, under the
\WM
Fig. 25. — CompouDd Hook of an lutermediate Shore-line near Willow Spring, Great Salt Lake Desert.
influence of the dominant waves, here from the north and northeast, traveled
from a to h. By less powerful waves from the east and south it was then
carried about the end of the embankment to the recurved point c, a point
with a peculiar and notable outline. On the lee side of the spit, at a point
where the Avaves could have no force after its construction, there are tliree
projecting tongues d, e, f, built of beach-rolled gravel and closely resembling
the extremity of the point c. The highest is twenty feet below the spit; the
others thirty and forty feet. They are evidently more ancient hooks, the
MON I 10
146 LAKE BONNEVILLE.
appendages of similar but shorter and lower spits, which may fitly be re-
garded as progi'essive stages of the huge table ultimately constructed.
Finally, the single element of order detected in the accumulated pro-
files is by this hypothesis shown to be consistent with the general want of
order. The terrace (a, PI. XXIII) lying from 15 to 25 feet below the high-
est Bomieville embankment, was preserved because it was the penultimate
deposit of the ascending series, and because the ultimate deposit was too
meager to mask it. The differentiated series of Bonneville bars described
in a preceding section shows that the penultimate water stage was about 20
feet below the ultimate. Wlierever the penultimate contribution to an em-
bankment w^as made upon its lakeward face, it escaped concealment by the
final contribution, which was small in amount and was perched u2)on the
top of the same embankment.
The second hypothesis is thus sustained at all points. The Intermedi-
ate embankments record the wave action of an oscillating water surface.
Within this zone the water level did not long linger at any one horizon, or
if it did, the record of that lingering was effaced by later action.
It follows as a corollary from this discussion that cut-ten-aces with
their associated sea-cliffs afford a more trustworthy record of persistent
water stages than do embankments. It is an additional mark of persistent
stages that they afford coordinated terraces and embankments.
It is impoi'tant to note, however, that neither the sea-cliff nor the cut
terrace, if observed alone, affords satisfactory evidence of persistent wave
action at one horizon. They must be found together. A slowly rising
tide continually abandons the freshly cut teiTace and attacks with its waves
the freshly cut cliff above it. In this way a cliff is carried before the ad-
vancing water of an oscillating lake ; and when the ma.ximum is reached
and recession follows, the cliff is stranded, so to speak, at the upper limit,
even though the water margin was retained there a short time only. Sim-
ilarly, it is conceivable that a falling lake sm-face may carry before it a cut
terrace without leaving at any horizon a sea-cliff of comparable magnitude.
The first of these conclusions has an application in the case of the Bonne-
ville shore-line, which, as already remarked, is characterized by the great
height of its sea-cliffs, but is inferior to the Provo shore-line in the widtli
CIIARACTBRS GIVEN BY STABLE WATER LEVEL. 147
of its cut terraces. The considerations here adduced serve to complement
the ])artial explanation of this contrast advanced on page 129.
As already intimated, the compilation of the Intermediate embankments
was the result of a series of oscillations of the ancient lake, whereby a zone
of wave action was carried alternately upward and downward over the
slojie. The basis for this statement does not lie in the embankments them-
selves so much as in the associated lacustrine and alluvial deposits. It is
imquestionably true that the entire history of oscillation is embodied in the
internal structures of the embankments, but these are not exjjosed for exam-
ination, and the external forms afford information for the most part only of
the Litest additions.
It is a curious fact that these forms of embankments appear to have
been moulded by a gradually rising rather than by a falling tide. The last
general movement of the water was of course a recession, for the slopes are
now dry, but that recession has left so little trace above the Provo horizon
that we are led to believe it was far more rapid than the preceding advance.
This conclusion is as interesting as it was unexpected ; and it is proper
that the evidence on which it rests be presented somewhat fully, especially
as it has been assumed by several investigators, including myself, that
the several shore marks of the series represent lingerings of the ancient lake
during a gradual recession.
SUPERPOSITION OF EMBANKMENTS.
The snowpiow.- Ill tlio first placc, there are many superficial indications of
the overlapping of low embankments by high ones. If the reader will turn
to the map of the Snowplow (PI. XIX), he will see that the table lettered a
is not entirely supported by the table b, but projects a little on the south
side so as to rest partly upon the general slope which is the common founda-
tion of both. (It is necessary to restore in imagination the contours inter-
rupted by the (h-ainage line southeast of the letter a and dividing the
embankment it indicates.) As has already been explained, the material of
the Snowplow Avas derived from the region fff, and was di-ifted along the
shore from southeast to northwest. That which composes the upper surface
of each embankment must have been carried along the southern edge of the
148 LAKE BONNEVILLE.
Snowplow by beach action, so that each embankment was, at the time of its
completion, connected by a continuous beach with the source of supply. The
embajikment h is not so connected, for the evident reason that its southern
edge has been overlapped b}' the latest addition to embankment a. If the
waves during the recession of the water had made a contribution to the lower
embankment, they must either have excavated the side of the upper embank-
ment or else have built a platform around it, and in either case the slope from
the crest of the upper to the foundation plain would not have the observed
uniformity and steepness. A similar relation of parts shows that the em-
bankment 1) was completed after the embankment c, so that at least three of
the members of the series received their final moulding in ascending order.
Reservoir Butte.-At Rcscrvoir Butto Substantially the same story is told, but
in different language. The face of the butte turned toward the open lake
was rugged in the extreme, and the configuration of the neighboring bot-
tom was irregular, so that, as the depth of the water changed, the conditions
determining the transfer of shore drift and the construction of em];)ankments
were continually modified. The resulting embankments were not built into
a synnnetric system but Avere thrown together in an irregular and unique
group. By referring to Pis. XXIV and XXV, where they are represented
by vertical and horizontal sketches,^ it will ,be seen that, of those above the
Provo, the highest is tlic last formed, overlapping all the others. Number 2
(tli^y are numbered in the order of height) has no visible connection by
beach with the north or weather face of the butte, whence its material was
derived; and its form and relations show that it could not have been con-
structed after the completion of Number 1. The third and part of the fourth
are in a similar manner overplaced by the second, and were evidently earlier
fomied. The fourth is however separable into two parts, which may have
been formed at different times; and the outer, marked 4« in the diagram, is
not so related to No. 2 as to demonstrate the order of sequence. It is hoAvever
overplaced by No. 1. The relative age of the third and fourth is not appar-
ent; but tho fifth, which lies; in a bay completely sheltered by the fourth, is
evidently of greater age. The sixth and eighth have no detenniued relation
' Tho plat of tlicso eraljankiucnts Riven in PI. XXV cinnot claim the accuracy of other maps of
embankments. It was sketched in the field without the aid of instruments, and may be very inaccu-
rate in matters unessential to the discussion above.
SUPERPOSITION OF EMBANKMENTS. 149
to any other except the first, which they underlie; and the seventh, which
projects from beneath the fourth, shows no direct relation with any other.
The ninth is the Provo, and this proclaims its recency l)y its relation to the
first. Its table extends to the north face of the butte, and not merely passes
the face of the first or Bonneville emljankment but is in part carved from it.
The Provo waves encroached also upon the eighth embankment. These
relations may be tabulated in the following form, in which the word "ante"
should be construed to mean completed at an earlier date than.
^ \ ante 2
5 ante 4 \
- > ante 4a
• ante 1 ante 9
stockton.-Another unique aggregate of embankments is equally instruct-
ive. Previous to the rise of the lake, the drainage of Rush Valley was tribu-
tary to that of Tooele Valley, the connecting parts having a continuous
descent from south to north, and an ample channel, of which a portion is yet
clearly to be seen. At the point of greatest constriction between the two
valleys, where the Bonneville strait had a width of only 8,000 feet, the bot-
tom of the channel ran about 350 feet below the level afterward marked by
the Bonneville shore. At all high stages of the lake the strait received a large
quantity of shore diift from the northeast, and a series of curved bars were
thrown across it. These bars have a total width of 5,000 feet, and partially
overlap each other, so as to constitute a single earthwork of colossal propor-
tions. Whenever the water surface fell below the highest completed bar, the
Rush Valley bay was completely severed from the main body, and became
a lake by itself This lake was so small that its waves were comparatively
powerless; and, although traces of their work can be discovered, they did
not materially influence the configuration of the earthwork. The locality is
exhibited in the foreground of the view in PI. IX and in the map and 2;)ro-
file of PI. XX. If the reader will refer to the latter plate and give attention
to the profile in connection with the map, he will see that the bars rise in
consecutive order from a to g, and that each has a curved axis with concavity
toward the north. This curvature, which is characteristic of bay bars in gen-
150 LAKE BONNEVILLE.
eral, shows that the waves concerned in their production came from the north.
It is evident that after the bar b was constructed, the bar a was protected
from all further wave action, a was therefore completed before b was built;
and in general the order of construction could not have been other than the
order of the letters, — the lowest bar a being the first, and the highest bar g,
the last. The order of construction was therefore from low to high. It is
to be noted that this order is demonstrated only for the visible or superficial
portions of the earthwork. There may be beneath the bar ff, for example,
a deeply buried series of bars lower than a, and either younger or older; and
so of any other of the higher bars. We have no reason to believe that the
whole history is embodied in the visible phenomena.
The bar g diff"ers from the others in that it is not unifoiTQ in height
thi'oughout its length. The lowest point of its crest is approximately in the
position occupied by the letter; and from this there is an ascent of about 30
feet toward either shore. At the Bonneville stage the strait was not closed
by a bar, but the shore drift was built into spits. That at the west is short
and has the fonn of a hook. It is crested from end to end by a slender ridge,
built at the cuhninating water stage. The eastern is straight and broad and
6,000 feet in length. Its proximal end bears two small spits, referable to the
cuhninating stage of the water; and its distal end evidently overlajis the
lower members of the compound earthwork. So far as outward api)earance
goes, this is purely the product of shore action at the Bonneville stage ; but
it is possible that similar spits were formed at lower stages, so as to consti-
tute a foundation for the Bonneville spit.
One of the most striking features of the series of bars is the paucity of
wave marks upon the northern face. There is a diminutive bar, character-
ized by an abundance of tufa, imposed on the face of the gi-eat bar g four
feet below its crest ; and twelve feet lower a wave-cut terrace is barely per-
ceptible. These may record an oscillation of the water after the comple-
tion of the great bar and before it rose to the Bonneville shore ; or they
may have been produced by the receding water after the highest level had
been touched. In any event, the final recession must have brought every
foot of the northern slope of the earthwork within reach of the waves, and
SEQUENCE OF BARS AT STOCKTON. 151
the surviving continuity of the slojie testifies to the rapidity of the reces-
sion. The conditions for wave work were unchanged. The alluvial slopes
which had furnished the gravel for the several embankments, still offered an
inexhaustible supply, and the same currents and waves must have been set
in motion by the storm winds ; but the lake seems not to have tarried long
enough at any one level to add a terrace to the structure.
Another evidence of the rapidity of the final descent of the waters is
found in the fixilure of the waves at any of the Intermediate horizons to un-
dercut the embankments constructed at the higher stages. If the water
tan-ies long at one level, the changes it effects in the form of the shore
finally modify the currents so as to shift slowly the districts of erosion and
of construction. Spots that were at first excavated are afterward made to
receive deposits, and portions of the original deposit are afterward removed.
Instances are known in which the Provo waves have pushed their excava-
tion to the heart of the Intermediate embankments, so as to undercut even
the highest members ; and there are few localities of great wave action
which do not exhibit more or less encroachment ; but there is no evidence
that the waves of any Intermediate stage have seriously impaired any higher
embanlanent. There is a narrow wave-cut terrace on the north face of the
Stockton earthwork ; two lines are engraved on the points of Intermediate
terraces in the Snowplow; and there is possibly a similar occurrence in
Preuss Valley ; but no locality gives evidence of long-continued action.
Blacksmith Fork.-Thc uudercuttiug of the Provo shore has in two places
exposed instructive sections of the Intermediate embankments. At the
south end of Cache Valley, close to the point where Blacksmith Fork
issues from the mountain, there is a section, nearly 300 feet in height, show-
ing a face of clean gravel, which has slidden down so as to cover the entire
surface — if, indeed, it does not constitute the entire mass. At four horizons
this is barred across by level lines of cemented gravel marking successive
positions of the upper surface of the mass as it was piled.
Dove Creek.- A siuiilar cscarpment of gravel is exposed on the soiith face
of the Dove Creek group of embankments (see profile diagram on PI.
XXII.), and a similar series of parallel lines can be traced across it. They
are best seen from a distance, and on close examination prove to consist
152 LAKE BONNEVILLE.
merely of a scattering growth of bushes. There is no visible variation in
the character of the gravel, but the position of tlie bushes is doubtless di.'-
termined by the existence beneath the surface of relatively impervious strata.
Whatever the nature of these strata, they are elements of structnr(i iind
demonstrate the growth of the series of embankments from the base iipward.
The featm-e especially interesting is the relation of the section to the unim-
paired eastern face of the embankment group. Each line ttf division is the
continuation of the iipper plane of a terrace, so that the terraces are shown
to be units of stratiiication. The evidence from external foiTu is thus con-
nected with that from internal structure ; and the general conclusion in
regard to the succession of the Intermediate terraces is strengthened.
Here, as in the other localities mentioned, it is necessary to guard
against the impression that the entire history of the lake during the forma-
tion of the Intermediate shore-lines is revealed l)y what can be seen of the
embankments. These structure lines do not extend through the entire mass,
and no other lines replace them. Those portions of the general mass of
detritus which lie next to the original hill slope may have been accumulated
by rising or falling waters, or, for aught we know, by a surface subjected
to many oscillations. In the case of the Snowplow, all that we can predi-
cate is that the latest additions to the mass were made in ascending order.
With reference to the Stockton eartliAvork, we know only that, of a certain
series of visible bar crests, the order of height is also the order of date. It
is not only possible but even probable that the series is discontinuous, hav-
ing been interrupted by epochs when the water was too low to add to the
accumulations at this point.
Double Series in Preuss Valley.-But, Avllilc it WOuld liave bcCU iuipOSsiblc tO gaiu
a knowledge of the repetitive movements of the lake surface from shore
phenomena alone, they nevertheless serve to supplement the information
afforded by the lake sediments. Having learned from the sediments, as
will be explained in anotlier place, that the wati'r rose at least Uvice from
the lower to the higher parts of the basin, besides undergoing many, minor
oscillations, it was not difficult to see that certain of the shore embankments
were referable to an earlier flood than certain others. The most important
locality is illustrated by the map and sketch of PI. XVI, and shows a series
DOUBLE RECORD IN PREUSS VALLEY. 153
of curved bars (h hh hj, overlapped by a series of spit-like embankments
massed together into a few sloping terraces (t t t). The source of the shore
drift was at the north, and the beaches which conveyed it to tlio curved
bars are hidden b)' the later erabaidcments. It would be impossible for the
bars to originate under the lee of the spits. Moreover, the spits everywhere
exhibit their gravelly constitution, but the curved bars are half buried by
lake deposits.
DELTAS.
The earliest allusion to the deltas of the ancient lake is by Bradley,
who remarks tliat the lake terraces " are much more numerous near tlie
mouths of the streams, where the stream-currents have distril)uted their
sediment, when the lake waters were at these higher levels";^ but the
first clear discrimination of the deltas from other terraces was by Howell,
whose observations were made only a few months later. Speaking of the
horizon of the Provo shoi'e-line, he says : — "When the old lake stood at this
level, the detritus brought down liy the Provo River formed a delta, cov-
ering at least twenty thousand acres. Another delta was formed at this time
at the mouth of Spanish Fork Canyon, in the same valley, which covered
an area of eight thousand or ten thousand acres.""
It was the magnitude of the former of these deltas that led Plowell to
suggest the application of the local name Provo to the shore-line at that level.
It is now known not only that all of the more notable deltas of the basin
appertain to the same shore-line, but that the delta built by each stream at
that level equals or exceeds in mass the aggregate of its deltas at all other
levels. At higher levels such accumulations are exceedingly rare ; and at
lower they appear to have derived their material largely from the partial
destruction of the Provo deltas.
In attempting to translate these facts into terms of geologic history, the
first impression is that the lake surface was held at the Provo level during
more than half the period of its existence, but a fuller consideration shows
that this conclusion is not warranted. The degradation of the uplands and
the offscouring of the rivers are doubtless sufficiently uniform in rate to
'Frank H. Bradley: Geol. Surv. of Terr., Ann. Rept. 1872, p. 192.
2 Edwin E. Howell : Geol. Surv. West of 100th Meridian, vol. 3, p. 250.
154 LAKE BONNEVILLE.
afford the basis for a time scale, but there are important modifying condi-
tions given by tlie relations of the oscillating lake surface to the configura-
tion of the stream valleys.
In the discussion of shore processes, it was pointed out that the detritus
brought to a lake by a small stream is absorbed by the shore drift, while
that brought by a large one overwhehns the shore di-ift and records its acces-
sion by a delta. The codeterminauts are, on the one hand, the magnitude
of the lake and the consequent force of the waves, and on the other, the
volume of the stream's load of detritus. In the case of Lake Bonneville,
the number of streams competent to project deltas from the shores of the
open lake or of the larger bays, was small; and it is believed that all of
their ancient mouths have been examined. With very few exceptions, they
enter the lake basin through mountain gorges so deeply eroded before the
lake epoch that the rising water set back into them, forming naiTOw estua-
ries. Knowing as we do from the study of the Intermediate shore embank-
ments that the water rose slowly as it apjijroached the highest level, we can
not doubt tliat the stream di-ift was contemporaneously accumulated into a
series of deltas within the mountain gorges. Afterward, when the water
fell rapidly to the Provo level and there rested, the streams attacked the
deltas in the defiles and carried their substance farther lakeward to form
new structiires. These new structures began for the most part within the
walls of the defiles, and were progressively built outward until they pro-
truded into the open lake, where space permitted them to develop into typ-
ical fan-shaped deltas. 'The material furnished by the older deltas in the
defiles was close at hand, and in a condition peculiarly favorable for
removal. Not only was it uncemented, but it was confined to the very
courses of the streams, so that it could not escape their action. It must have
been rolled to its new position hi an exceedingly short time ; and we need
not be surprised that the traces of its original forms are nearl}- ol)literated.
The rapidity with wliich delta alluvia are torn up and carried away bv run-
ning water finds al)undant illustration at the present time in the irrigation
districts of Utah. Wherever the water of a canal breaks through its bank,
or is neglected and suifered to discharge unguided down a delta slope, it
quickly erodes a canada of formidable proportions.
DELTAS OF LAKE BONNEVILLE. 155
Deltas associated with the Provo shore are thus composed not merely
of tlie contemporaneous outscour of the catcliment basins of their several
streams, but of the detritus antecedently accumulated in the estuaries dur-
ing the higher water stages ; and, so far as they afford a time ratio, they
represent the entire period during which the water stood at and above the
Provo horizon. There are, however, a few exceptional localities where the
Bonneville estuaries were so small and shallow that the stream drift not
merely filled them but threw out semicircular capes into the Bonneville
lake ; and in such cases it is possible to make a comparison between the
magnitude of the structures pertaining severally to the Bonneville and
Provo epochs.
American Fork Deita.-Tlie best locaHty for such obscrvation is on a tributary
of Utah Lake known as the American Fork, and this was carefully exam-
ined for me by Mr. Russell. The Bonneville delta there displayed has a
radius of nearly 5,000 feet, and a height at its outer margin of 120 feet. It
is bisected by the creek, and is thus cut nearly or quite to its base. The
walls of the channel exhibit a section of the deposit, showing it to consist
chiefly of rounded gravel, with some intermingled sand. The gravel, being
uncemented, will not hold an escarpment, but flows down in the fonn of a
talus wherever it is excavated by the stream, thus masking the greater part
of the stiixcture. There is, however, some indication of horizontal bedding.
The outer margin of the terrace is fortunately more communicative. Around
three-fourths of its periphery there runs a narrow shelf half-way down the
steep face ; and the details of this shelf show that it is the protruding edge
of an older and lower delta terrace, furnishing the foundation for the
upper. At some points lake beds were found intercalated with the alluvial
gravels, but they appear to be local deposits and not continuous sheets
traversing the whole body. The most complete local section has been intro-
duced into the accompanying diagram, and presents the following sequence :
6. Well rounded gravel, forming the top of the upper terrace; 20 feet.
5. Lake beds; laminated clays with .dmnicoJa; 30 feet.
4. Well rounded gravel ; 15 feet.
3. Well rounded gravel cemented at the top by calcareous tufa ; constituting a bench on the
face of the terrace ; 20 feet.
2. Well rounded gravel ; constituting locally a distinct bench ; 25 feet.
1. Lake beds, to foot of slope, 10 feet.
156
LAKE BONNEVILLE.
The continuity of the gravels 3 and G throughout the whole mass is
shown by their relations to tlie topography. Each marks a water stage
during which a broad delta was built in the lake. The beds numbered 2
and 4 are identical in charactcu-, and may be salients of similar deltas, here
locally brought to light and elsewliere comjdetely buried; or they may be
merely local masses of alluvium, marking the i)Ositions held ]jy the creek
during temporary fluctuations of the lake level.
At another point of the profile, a less complete section was observed,
exhibiting a rapid alternation of gravels and clays in the lower part of the
mass, and at a few other points short tongues of gravel were seen to project
from the table at various levels.
Flu. :i*i.— Ucuoralizud soctiou or Deltas at the mouth of American Fork Canyon, Utah. By I. C. Russell. Uonzontal
scale, 4,500 feet = 1 inch. Vertical scale, 300 feet = 1 inch.
These indications of complexity of structure accord well with such con-
ceptions of the oscillation of the lake at these stages as we have derived from
the phenomena of the Intermediate embankments. If its surface was incon-
stant, rising and falling, like the surface of Great Salt Lake, with an irregu-
lar rhythm, all processes of deposition at the mouth of a stream would be
successively interrapted, and any detailed section should show e^adence of
alternation. A rising tide would induce the formation of a delta far up the
slope and give opportunity for the accumulation of lake beds farther do\\n.
A falling tide would cause the stream to deepen its channel by the partial
erosion of the incipient delta, and perhaps of lake beds also,' and would
cause a local deposit of gravel at some lower level. A reascent would re-
OLD DELTAS OF AMERICAN FORK. 157
pair the breach in tlie delta, and a redescent might conduct the stream drift
in some new direction. The same oscillations would carry the waves to all
parts of the surface and enable them to work over the detritus, adding their
tribute to the general confusion.
Assuming that the water did actually oscillate to and fro during the
compilation of the delta, it is manifestly impossible to trace in detail and in
true sequence the processes which make up its history. The most that can
be affirmed is that a definite stage is marked at the liorizon of Bed No. 3,
where the water stood long enough to complete a well developed delta ter-
race, and that a similar definite stage is marked by Bed No. 6, which is a
continuous delta sheet almost coincident in area with the one below. The
lake level rejiresented by this higl ;st delta falls within the range to which
the Bonneville shore-line pertains, but was not the absolute maximum. It
is probable that the latter is represented by a shoal-water bar which crosses
the south part of the delta with a crest about 20 feet higher than the delta
margin.
The locality thus exhibits at least three ancient deltas, of which the
order of position is : —
Bonneville delta; capped by Bed No. 6.
Intel-mediate delta; capped by Bed No. 3.
Provo delta.
In the order of time the Intermediate comes first and the Provo last.
The Intei-mediate was built; the Bonneville was spread over its back, but
failed to cover it coniijletely; the lake fell, and the two were eroded by the
creek, the Provo being formed at the same time. Finally tlie Provo shore
also Avas abandoned by the lake water, which receded to its i)resent position
in Utah Lake. The creek has opened a broad passage through the Provo
delta, cutting it at the outer margin to its base, and is engaged in building
a modern delta in the modern lake. The apex of this delta lies within the
channel through the Provo delta, and is continuous with the flood plain of
the upper course of the stx-eam.
The modern stream Ijed has a more rapid fall than the ancient, as will
be seen by comparing the profiles of the modern flood plain and the Provo
delta, as exhibited in the diagram. This is due chiefly to the lowering of
158 LAKE BONNEVILLE.
the stream's mouth; but it is also due in part to the elevation of its point of
issue from the mountain. A recent fault has lifted the movmtaiii witli refer-
ence to the valley through a space of 70 feet.
Tliere is perhaps no locality more favorable than this for the estima-
tion of the time ratios of the higher lake levels, but even here it is f;n- from
satisfactory. The Provo delta of American Fork coalesces with the con-
temporaneous delta formed by the next creek to the north in such way that
it is impracticable to di-aw a line of separation; and there is no record of
the tribute made by American Fork during the rising of the lake until
it reached a level barely 100 feet below the Boimeville. Nevertheless, it is
instructive to make such comparisons as the circumstances })ermit, and Mr.
Russell's field notes have enabled him to compute approximately the vol-
umes of alluviiun accumulated at the different levels.
MillioDH of
cubic yards
Voluiuo of Bonneville aud Intermediate deltas before erosion by the creek 330
Volume of alluvium conteniporaueously deposited in mouth of bed-rock canyon 5
Total volume of gravel furnished by American Fork while the lake leA-el was within
100 feet of the highest stage 335
Volume of Provo delta of American Fork (the separation from delta of Dry Creek being arbi-
trarily made) - 400
Deduct gravel derived from Bonneville and Intermediate deltas 28
Deduct gravel derived from mouth of bed-rock canyon 5
Total volume of gravel furnished by American Fork while the lake stood at the Provo
level »67
If these quantities were well ascertained, instead of being rudely esti-
mated, they would show the gravel tribute of the stream to have been sliglith-
greater during the Provo epoch than during the last 100 feet of the antece-
dent rising, and would warrant the inference that the time during which the
lake level lingered within 100 feet of its highest mark was slighth- exceeded
l)y the duration of the Provo stage; and, after all allowance has been made
for imj)ei'fection of data, there remains a presumption that the Provo epocli
is comparable in dui-ation with the epoch or epochs recorded by the upper
deltas.
Mr. Russell has computed also the volume of gravel furnislied Ijy the
creek after the completion of the Intermediate delta, finding it to be 153
■ TIME RATIOS. 159
million yards. This represents the tribute of the creek for all lake changes
within 50 feet of the maximum, and includes the Bonneville tribute. Its
ratio to the estimated Provo tribute is as 5 to 12. It is perhaps fair to as-
sume that one-half of this mass pertains to the Bonneville shore proper;
and on that assumption the indicated ratio of the epochs of the Bonneville
and Provo shores is as 1 to 5. Quantitatively, this estimate has not a high
value, but qualitatively it serves to confirm the impression derived from
the wave work of the Bonneville and Provo shores.
It is worthy of note that the only halt of the lake surface which here
finds record between the Provo and Bonneville horizons, was a halt of the
advance and not of the retreat. The Intermediate delta is unmistakably
older than the Bonneville; and there is none younger except the Provo.
There was of course no cessation of stream action while the water of the
lake was falling from tlie high mark to the low. The creek must have be-
gun the erosion of the Bonneville delta as soon as its point of discharge
was at all lowered by the recession of the lake; and the product of that
erosion must have been deposited at the mouth of the creek in the form of
a delta or group of deltas, but the eroded channel was so narrow and the
resulting deposits were of so small bulk that later action destroyed them.
Wliile the Provo delta was being built the channel through the Bonneville
was enlarged nearly to its present dimensions, and no stream terrace sur-
vives to mark the earlier stages of its excavation. In the same period the
creek tore down and removed whatever deltas it may have built at the shore
of the receding lake. If the lake had halted and lingered by the way, the
creek would have been able to carve a broad flood plain and spread a broad
delta, some vestiges of which would survive ; and we can legitimately infer
from their absence that the recession of the lake was rapid and without in-
terruption until the Provo level was reached.
When the lake afterward shrank away from the Provo delta, its move-
ment was less precipitate. The channel then opened by the creek has a
maximum depth of only 70 feet, but five separate stream terraces, cut from
its right wall, record the hesitation of the water as it fell.
Logan Delta.- One of tlio most beautiful and symmetrical of all the deltas
is that constructed by Logan River at the Provo stage of the lake. The
160 LAKE BONNEVILLE.
river enters Cache Valley from the east, debouching from a bold mountain
front through which it has eroded a narrow V-form canyon. At the mouth
of the canyon the Bonneville shore-line is engraved on the rock nearly five
hundi-ed feet above the river, and the grade of the river bed indicates that
when the line was cut the lake water set l)ack into the nan-ow way a dis-
tance of about four miles. There are are some slight traces of gravel ac-
cumulations within the canyon, but it probably was only partially filled,
and certainly no delta was foi-med in the lake at the Bonneville level. If
any estuary existed at the Provo stage it was small and quickly filled with
alluvium. The apex of the Provo delta is at the mouth of the canyon, and
about this point as a center the margin describes an arc of about 130 degi'ees
with a radius of 8,000 feet (see map and profile of PI. XXVI). Tlie upper
surface is visibly and distinctly conical, having a radial slope in all direc-
tions from the apex of 55 feet to the mile, or three-fifths of a degree from
the horizontal. At the margin this gentle inclination is abruptly exchanged
for a declivity of about 20 degrees. At the north the terrace joins and coa-
lesces with a similar and contemporaneous but smaller terrace pertaining to
what is now a small creek. The marginal height of tlie terrace is about 125
feet. During its construction the river occupied every part of its surface in
turn, and when the construction work was brought to an end l)v the lower-
ing of the lake, and the excavation of a channel was begun liy the ri\er,
the position of that channel was determined by the chance position (tf the
shifting stream. It is not medial, but bears so far to the south tliat the
northern remnant of the delta is two or three times greater than the southern.
As soon as the erosion of the Provo delta conunenced, the 1)uilding of
a new delta Avas begun at a lower level, and the apex of the new delta was
at the mouth of the channel through the Provo. With the progressiA'e low-
ering of the lake, yet other and lower deltas were built, the construction of
each being accompanied by the partial or complete' destruction (»!' tliose
above it ; and this continued luitil the desiccation of the valley. For two
miles below the Provo delta, each Ijiiiik of tlie modern river is lined by the
remnants of these old deposits, four or five lying on each side. One of the
most conspicuous has been selected as the site of the Logan Temple, and
two lower benches are occupied by the town of Logan. A glance at the
I- S. GEOLOGICAL SURVEY
LAKE BONNEVILLE FLXXVI
MAP OF THE
D 1", I.T A S
1.11 mc-a 111
AKE nONNKVIlJ.I':
bv llii-
LOC.AN KIVEK
Rv ^V'^ D Joliiisoii .
''WiJii'flfP"'''"''
Pro 111 e
Vertit'ol Sivii- ilouOlc the Borixonin.1
ZS- feet Cyntmu's .
Temple
Jul,i,« Hicn .vi'o.l.th
Dravni by (* Tliompiji
OLD DELTAS OF LOGAN RIVER. 161
map will show their arrangement l)etter than any description. The river has
developed so broad a flood plain that half their mass has disappearetl, and
the dissevered remnants are too fragmentary to be readily correlated across
the interval. No attempt has been made to restore their forms and com-
pute their volumes, l)ut it is evident by inspection that they included no
ri^•al of the great delta above. Their renmants do not exceed in total bulk
the mass the river has dug from the upper terrace. They can have no
value as a basis for time ratios, because it is impossible to tell how nnich
they owe to the reworking of the material of the higher delta and how
much to the annual tribute of gravel brought by the river from the mount-
ains ; Init they serve to show, first, that the lake lingered by the way as it
receded from the Provo shore, and second, that its lingerings were not long.
The same lingei'ings have left record within the Provo delta in the
form of stream terraces, which abound near the mouth of the canyon. Mr.
Russell has recognized ten independent benches on the north side of the
stream and three on the south.
The view in PI. XX^^1I was sketched from the wall of the Mormon
temple standing on one of the lower terraces. It exhibits the Provo delta,
divided by the alluvial valley and overlooked by the Bonneville shore
mark, which happens to Ik; strengthened immediately above the delta by
an accumulation of shore drift.
The main delta, and probably all lielow it, rest upon a sloping floor of
lacustrine sand and clay. The modern bed of the river runs below the
bases of the deltas and within the zone of these sediments, Ijut exposures
are rare, l)y reason of tlie tendency of the uncemented delta gravel to slide
down and overplace it. The best exhibition at the time of our examination
was afforded by a fresh excavation for an irrigation canal along tlie bluff
north of the river, and was sketched by Mr. Russell. The strata show
many undulations beneath the Provo delta, but are relatively smooth be-
yond its margin. Mr. Russell suggests that the disturbance of the strata
may have been an incident of the building of the delta. At every stage of
the work there was a diftei-ence between the weights borne 1j}' the lake
beds beneath the delta and by those beyond it, and the line of sej^aratiou
was sharply drawn at the edge of the deposit. The conditions were there-
MON I 11
](J2 LAKE BONNEVILLE.
fore favorable for the deformation of the freshly deposited sediments by
differential jjressnre, some of the softer layers being made to flow out from
beneath the gravel. The difference in weight between the water on one
side and the saturated gravel on the other amounted to seventy-five pounds
to the square inch. As the delta was progi-essively increased by additions
at the outer margin, the zone of unecjual pressure; was correspomlingly ad-
vanced, until the whole substructure of the delta hail been subjected to the
action and deformed as far as its constitution permitted.
fnmo Vrlta,
Temple Delta
FLond. PtaOv
yv E.
Fig. 27. — Partial soctinii of Dolta.s at Lo^^aii, Utah, liy I. C. KuasoU. Vi-rtical scalo greatfr than hdrizunlal.
Wherever the body of the Provo delta is freshly exposed, it displays
an oblique lamination inclining in the direction of the lakeward margin-
The dip near the top of the deposit is 15 or 20 degrees, and diminishes
downward, the layers being disposed in sweeping, parallel curves. Only
a single locality exhibited (1880) the nearly horizontal beds which in a
normal delta overlie the inclined — a point half a mile below the canyon's
mouth, where the south bluff of the river had freshly fallen down, exposing
ninety feet at the top of the face. The series consists of:
r>. Fine sand, 5 feet.
4. Gravel, horizontally laminated, 10 feet.
3. Fine sand, 'i.') feet. /
2. A line of small boulders, unconformable to No. 1.
1. Gravel, coarse and fine intermingled; dipping 15° toward the SW. Exposed 50 feet.
Other Deitas.-Of tlic otlicr sti'eams of Cache Valley, as many as eight built
Provo deltas, and one. Spring Creek, probably formed also a small Bonne-
ville delta. The Cub Creek and High Creek deltas are small, and lie within
the flaring mouths of the canyons. Smithfield and Bell ville Creeks heaped
their tribute just outside the canyons. Blacksmith and Muddy Forks de-
bouched close together and built a confluent delta, larger perhaps than that
of the Logan, but less symmetric. The original or ante-Bonneville canyon
of Blacksmith Fork was so deeply cut that tlie modem .stream lias not yet
removed all the debris gathered during the lake period. The mass of allu-
L' S. 0EOL(iGlCAI. Srn\ KY
1„\KK BlIN.VEVlLLK PI, XV\ I
THE ANCIENT DELTAS OF LOGAN RH'ER, AS SEEN FROM THE TEMPLE.
INTERNAL STRUCTURE OF LOGAN DELTAS. 16;3
viiun stored in it at the Provo epoch was great, and contributed to the
t'orniation at lower levels ot" a fine series of deltas, on which stands the village
of Hyruni. Spring Creek issued from a canyon which was never cut down
to the Provo level, and the apex of its Provo delta was (piite outside the can-
\(tn. The modern stream is a mere rivulet that one may leap across; but
its delta liad a radius of two-thirds of a mile, "^llie history of the Bear River
deposits was not a\ ell made out. At the canyon mouth the river now Hows
at a level a few feet higher than before the lake })eriod, and tliat level is four
Imndred feet below the highest lake shore; but the modern river outside the
canyon is walled in by a great deposit, chiefly of sand, through which it has
opened a passage. There was clearly no Bonneville delta at this point.
The upper surface f)f the sand is a sloping plain, joining the mountain near
the canyon only fifty feet below the Bonneville shore. Unfortunately the
examination was made while snow lay on the ground, and the structure of
the deposit could not be seen. If it is a delta it is probably of the Provo
date, and its outer margin must be in the vicinity of Battle Creek Butte, ten
miles away. Otherwise it must be regarded as a lake sediment, which owes
its exceptionally great volume to the proximity of a silt-bearing river. In
either case its source of material is the river drift; and in either case its ac-
cumulation was probably contemporaneous with that of the deposits which
filled Gentile Valley, a small opening among the mountains at the head of
the canyon.
Outside of Cache Valley all the notable deltas except that of the Sevier
River lie at the western base of the Wasatch Range. The most northerly
is near Brigham City, on Box Elder Creek, ^ a stream rising in a small valley
just east of the main axis of the range, and cutting across it. In the upper
valley there are remains of a detrital filling-, which was probably coe\al
with Lake Bonneville, although not in visible contiimity with delta forma-
tions. The canyon through the mountain has been swept clean of debris,
except at the bottom ; and at its mouth there is a small composite delta, of
which the highest element has the Provo height.
The history of Ogden River is nearly the same, but its features are on
a larger scale. The upper valley contained so large a bay that a discernible
shore-line was carved therein ; and it is probable that some of its sloping ter-
' Not to be confounded with the Box Elder Creek of Tooele Valley, mentioned in connection with
the Grantsville embankments.
164 LAKE BONNEVILLE.
races are remnants of Bonneville deltas. The fall of the lake drained the
upper valley and led to the building of a broad delta just outside the mouth
of the canyon; but this delta is exce})tional to the general rule in that it is
somewhat below the Provo horizon. On the plain beyond it a series of ter-
races were afterwards formed similar to those at Logan. The city of Ogden
stands at the end of the series, and its suburbs encroach on some of the
lower benches.
Close to the Ogden deltas lie those of the Weber, less synunetric l)ut
far more massive. They extend from four to six miles in nil diroctions from
the mouth of the canyon. The channel cut through them by the modern
river is several hundred feet deep, and is exceptionally indirect, curving
through the fourth part of a circle. The broad flood plain within it supports
three agricultural hamlets, and is traversed by the Union Pacific liaihvay.
The westward-bound passenger issuing from the rock-bound defile of the
Wasatch at Uinta Station finds himself enclosed by walls of delta sand, and
does not fully emerge from the lowest terraces until he reaches Ogdt'U (Sta-
tion, a ride of eight miles. The greater portion of the stnicture lies on the
left or south bank of the river and is locally known as the Sand Ridge. It
is the largest of all the deltas of the ancient lake biiilt upon an open ])lain,
but, owing to the lightness of its material, the details of its form are imper-
fectly preserved. Portions of the interior of the mass ap])oar to be gravelK',
but the upper parts are chiefly composed of sand, so fine as to be moved
by the wind. The ])rincipal terrace is at the Provo level, and upon this
there stands a liill more than 200 feet high, which niav p(issi])lv l)e the
remnant of a more ancient and more lofty delta, but is probably a dune
accumulated during the Provo epoch. The lower terraces, marking the I'e-
cession of the water, were built on the north side. The south fai'e of tlie
Provo delta has been supei-ficially modified by subsequent wave action.
City Creek, the stream supplying Salt Lake City with water, rises in
the Wasatch Range and flows through a long canyon before emerging on
the plain. This canyon was capable of storing a large amount *)f alluvium;
and it is probably due to this fact that the Provo delta is smaller than tliose
at lower levels. The group of deltas constitute "the bench" on both sides
of the creek, and are composed of coarse, \\ell rounded gravel. While they
OTHER DELTAS. 165
were forming, a large amount of sliore drift soems to liave readied tlie lo-
cality from the southeast, and this modified the resulting topograjihic. iorms.
The configiu'ation of the bench owes nearly as nuich to the action of waves
as to the depositiini of stream drift.
The deltas formed by Little Cottonwood and Big Cottonwood Creeks
coalesced with each other, and probably with one from the Dry Cotton-
wood; but their outlines are greatly obscured by subsequent stream erosion,
and they have been further modified by a system of faidts.
P^ollowing the l)ase of the Wasatch southward, the next delta i-eached
is that of American Fork, already described. Beyond it, is the delta of the
Provo River, a broad low terrace of gravel spreading fan- wise from the
mouth of the Provo canyon. The radius of the fun is about 4^ miles, and
the terrace has a marginal height of 70 feet. It is skii'ted rather th;ni di-
vided by the modern river, which turns abruptly southward from the mouth
of its canyon. Lower deltas were only obscui'ely differentiated, but the
form of the lake shore indicates that the river is now constructing one.
The wagon road from Provo to Pleasant Grove crosses the mniii delta; the
railroads pass around it.
Near Provo City a small stream named Rock Creek issues from a short,
steep canyon in tlie mountain. It built a small delta, during the Pxnuieville
epoch, and another during the Provo; and these would afford an instructive
study in chronology Avere it not for the injury they have suffered from the
recent faulting. Hobl)le Creek, which irrigates the farms of Springville,
built a, well-marked delta at the Provo level, and proliably a small one at
the Bonneville. The subaei-ial alluvium here rests so high against the
mountain that it constituted the coast at the Provo stage, and the Provo
delta rests against it. Five miles southward Spanish Fork issues from the
range, with a northwesterly course. In the Boimeville lake it built a delta
with a radius of 4,000 feet, and in the Provo lake a larger delta coalescing
with that of Hobble Creek. At Payson a small creek formed a delta at the
Provo level. Salt Creek, the next stream issuing from the range, reached
the ancient lake only after flowing for some distance across the j^lain. Its
highest delta appears to be one at the Provo horizon, and lies at the south
end of Goshen Valley.
166 LAKE BONNEVILLE.
Apart from the di-ainage system of the Wasatch, only three deltas ^A-ere
observed. A small one lies in an open canyon back of the town of Port-
age, in Malade Valley. A larger was pro])ably foi-nied by Beaver Creek
at the Provo level near George's Ranch; but it is difficult in this case to
distinguish stream drift from shore drift.
The deltas of the Sevier River are more important. At the Bonneville
epoch alluvial terraces were built where the river enters Juab Valle}-, but
the topography did not |)ermit the formation of a broad fan. At the ProA^o
epoch a broad, low delta fan was built by the river on the i^lain between
Lemington and Deseret.
summary.-The contributious made by the phenomena of the deltas to the
history of the oscillations of the lake may be summarized as follows:
First, the Bonneville shore-line antedates the Provo.
Second, the Provo epoch was several times longer than the Bonneville.
Third, in falling from the Bonneville shore to the Provo the water lin-
gered very little, if at all.
Fourth, in falling from the Provo level to the bottom of the basin the
water occasionally lingered, but its lingerings were brief as compared to
the halt at the Provo level.
Fifth, the water lingered during its advance antecedent to the Bonne-
ville epoch, not standing long at one level, but oscillating up and
down.
A cei'tain significance attaches likewise to the absence of deltas from
the greater portion of the coast of the old lake. All of the olil deltas are
associated with modern streams; and all the modern streams of iiuportance
built deltas. It would appear, then, that the ancient climate did not create
important strc^^ams in regions where the outflow is now small. In the west-
ern portion of the basin, there are catchment districts of considerable extent
which furnish little or no water to the lowlands by reason of the scantiness
of rainfall. If the rainfall in Bonneville times Avas very great, as compared
to the modern, these catchment districts should liavc furnislicd tributarv
streams; and such streams, flowing over tracts of alluviuni, the accunndation
of ages, should have transported large quantities of it ti) the margin of the
lake and constructed deltas of it. We seem thus to have an intimation that
THE HISTORY TOLD BY DELTAS. 167
the climatic change, whatever its nature, did not affect the rainfall in a de-
firree commensurate with the difference in area of lake surface.
TUFA.
Calcai-eous tufa was deposited by many and perhaps all of the Pleis-
tocene lakes. In Lake Lahontan and the other lakes of the western portion
of the Great Basin, great masses were accumulated, and their study has
resulted in an important contribution to the Pleistocene history. In Lake
Bonneville very little tufa was foiTned, and its bearing upon the history of
the lake seems to be unimportant. It is associated exclusively with the
shores; and its amount upon individual shore-lines is in a general way pro-
portional to the magnitude of the other shore features. At least this rule
applies to the Bonneville, Intermediate, and Provo shoi'e-lines. The Provo
carries most of all; the Bonneville and Intermediate have an equable dis-
tribution.
Next to tlie Provo the Stansbury is most generously supjdied; Init this
shore is not characterized by endiankments and cliffs of great magnitude.
The extent of the lake was so greatly reduced at this stage that the i)ower
of the Avaves was materially lessened; and it is ])erhaj)s legitimate to infer
that the tufa records a })rotracted lingering of the falling water which does
not find adequate expression in other shore features.
In embankments the ])osition oecnpicd liy the tufa is on the Aveather
face a few feet lower than the crest. It lies just beneath the surface, and
has the function of a cement, binding the gravel together into a conglomerate.
Tlie association is far from being invariable; and indeed the majority of the
emT)ankments are uncemented. In regions of excavation the tufa occurs
just outside the edge of the cut-terrace, coating the lower slope for a space
of 20 or 30 feet. Its zone of maximum deposition was probably from 10
to 20 feet beneath the water surface.
Where the deposit is thin, it consists merely of a uniform film, but
wherever it acquires a thickness of an inch or more, there is manifested a
tendency to assume dendroid forms. These are not uniform in character,
but generally consist of branching stems, an eighth or a fourth of an inch
168
LAKE BONNEVILLE.
in diameter, frequently dividing and again joining, so as to constitute a
reticulated mass in which the interspaces are not large.
The composition is shown ])y the following analysis, copied from the
report of the Fortieth Parallel Survey, Vol. 1, page 502:
Analysis of Tufa\froin Maiv Terrace, liedding SpriiKj, 'Suit Jake Desert, by li. JV. Wooduard.
[Specific gravity, 2.4, 2.3, 2.4.]
Silicic acid (cbiefly iucluiled sand)
Alumina
Sfsquiosidu of iron
Lime
Ma<;ne8ia
Soda
Potassa
Litbia ...
Phosphoric acid
AV ater
Carbonic arid
Total
Percentages.
First,
sample.
Second
sample.
8.40
B.22
1.31
'.20
Tr.
Tr.
40.38
i. 50
3.54
3. .52
0.48
0.22
0.54
0.22
Tl.
Tr
Tr.
Tr.
1.71
38.20
1.62
38.33
100.24
100. 14
On p.iges 495 and 496 of the same volume, the microscopic cliaracters
of tlio tufa are described by King.
The distribution of the tufa along each shore is independent of the
nature of the subjacent terrane. The heaviest observed deposits are upon
quartzite and granite at a considerable distance from calcareous rocks. The
most conspicuous accumulations are upon rock in place, but this difference
probably depends u])on the fact that deposits upon unconsolidated material
are largely interstitial. A more important peculiarity of the distribution is
its relation to wave action. No deposit is found in sheltered bays; and on
the open coast those points least protected from the fury of the Avaves seem
to have received the most generous coating. These characters indicate, first,
that the material did not have a local origin at the shore but was derived
from the normal lake-water; second, that the surf afforded a determining
condition of deposition. It will appear in a later chajiter that calcareous
'The analysis is headed "Thiuolite (pseudo Gay-Lussite) " — prohably thnmjih inadvertence, for
the reference to the analy.sis in the text (p. 4%) iise.s the dpsit;nation tufa only ; and the iheory in res-ird
to the origin of the Lahontan tnfa which is cnihodicd in llic term "psendo Gay-Lussite," appears from
the context not to have been applied to the Bonneville basin.
TUFA. 169
matter constitutes an important part of the fine sediment of the hike bottom,
and that this was chiefly or wholly precipitated from solution. It is not
easy to see why this deposition should consist of discrete particles in the
open lake and be welded into a continuous mass upon the shore; but a par-
tial explanation a})pears to be afforded by the hypothesis that the separation
was promoted by the aeration of the water. All precipitation being initiated
at the surface during storms, coalescence at the shore niay ha\'e resulted
from contact at the instant of separation. The suggestion finds a certain
amount of support in the part played by nuclei as determinants of precipi-
tation.
The thickest deposit anywhere observed is on the outer verge of the
Provo terrace at the north end of Reservoir Butte, where there is a, maxi-
mum of four feet. The tufa, there coats a knob of solid quartzite so situated
that while it was fully exposed to the surf, whatever the direction of the
wind, it was exempt from attack by shore drift. The locality is exceptional;
in most places where the tufa is so abundant as readily to attract attention,
its depth is measured by inches.
An allied deposit may be mentioned in this connection, namely, oolitic
sand. This was fiist observed on the Bonneville shores by Miss Susan
Coolidge, of Grantsville, Utah, and was afterward found by Messrs. W. J.
McGee and George M. Wright on several shore terraces at the north end of
the Oquirrh Range. It is now forming in Great Salt Lake along the coast
between the delta of the Jordan and Black Rock, where it constitutes the
material of a beach, and is drifted shorcAvard in dunes. Like the tufa, it is
exclusively a shore formation, but the circumstances connected with its
occurrence on the modern shores of Gi'eat Salt Lake and Pyramid Lake
warrant the suspicif)n that it is not e(iually independent of local sources of
supply. The locality mentioned on the shore of Great Salt Lake is near
the mouth of a stream whose annual tribute of carbonate of lime can not
be small, and the only known locality on Pyramid Lake is associated with
hot calcareous springs.
RE8UMfi.
The highest of the shore-lines jireserved on the slopes of the basin,
namely, the Bonneville shore-line, has an altitude of 1,000 feet above Great
170 LAKE BONNEVILLE.
Salt Lake. By reason of its position at the top of the series, it is the most
conspicuous of all; but the one most deeply carved is the Provo, 375 feet
lower. Between the Bonneville and Provo are the Intermediate shore-
lines, characterized by embankments of great size, but without" correspoiid-
ingly great sea-clifFs and terraces. Below the Provo tlie .slopes exliiljjt lake
sediments, with occasional shore-lines superposed. Of these latter the Staus-
bury is the most prominent.
The area of the lake at the Bonneville stage was 19,750 square miles;
at the Provo stage, about 13,000 square miles; at the Stansbury stage, about
7,000 square miles.
The order of sequence of the shores to which names have been given
is: first. Intermediate; second, Bonneville; third, Provo; fourth, Stansbury.
During the period of the formation of the Intennediate embankments, tliere
were no persistent water stages; but the water surface oscillated uj) and
down. The last additions to the embankments were made during a gen-
eral advance of the water. The oscillation of the water surface continued
through the Bonneville epoch, the Bonneville shore representing the cnm-
bined results of wave action at a series of water levels having a vertical
range of 20 feet. The last stage of this series was the liigliest, and imme-
diately afterward the surface fell ra})i(lly to the Provo horizon, where it
remained a long time. The water margin afterward receded from the
Provo shore to its present position, halting occasionally by the way, and
longest at the Stansbury sliore.
CHAPTER IV.
THE OUTLET.
Tliirteen years ago I had the temerity to predict,^ first, that the position
of the Bonneville shore-line would eventually be shown to have been deter-
mined by an overflow of the lake, and second, that the Provo shore-line
would be found to have been similarly determined. The first of these pre-
dictions has been verified in its letter, but not in its spirit; the second has
proved to have full warrant. My anticipation was based on the following
consideration: A lake without overflow has its extent determined by the
ratio of precipitation to evaporation within its basin; and since this ratio is
inconstant, fluctuating from year to year and from decade to decade, it is
highly improbable that the water level will remain constant long enough to
permit its waves to carve a deep record. I failed to take account of the
fact that the highest shore-mark of the series is conspicuous by reason of
the contrast there exhibited between land sculptni-e and littoral sculpture.
We now know that the height of the Bonneville shore-line was determined
in a certain sense by overflow, since a discharge limited the rise of the
water; but the carving of the shore was essentially completed before the
discharge; and as soon as that began, the water level fell. At the Provo
horizon, on the contrary, a constant or nearly constant water-level was
maintained by discharge for a very long time.
The outlet of a lake is necessarily across the lowest point of the rim of
its basin; and it is essential that this point be somewhat lower than the
water level of the lake. The search for an outlet to Lake Bonneville was
therefore a search for a pass in the rim of the basin lower than the neigh-
' Expl. West of the 100th Mer., vol. 3, pp. 90, 91.
171
172 LAKE BONNEVILLE.
boring shore-lines. It is e(|ually necessary tluit tli(! liasin on the opposite
side of tlie ])ass he connj)etent to receive the discharged water. It nnist
either drain to tlic ocean or else be snfficiently large and suflicicntl\' arid to
dispose of tlie afflncnt water ])y evaporation. TIh^ conditions of outlet
having been satisticd, and a discharge having been produced, it is ('(|ual]y
evident that the process of that discharge would modify the topographv in
a peculiar manner. A channel would be produced at the pass, and this
would descend in one direction only, its sides and bottom merging at the
pass into other topographic features. The site of the ancient outlet of Lake
Bonneville should therefore exhibit a channel, the bed f)f which is lower
than the contiguous shore-line, and the de.scent of which is toward some
basin competent to receive and dispose of the water.
It is quite C(mceivable that a basin like tlie l)onneville, known to ])e
subject to deformation through hypogene agencies, should discharge its
surplus water at one time over one pass and afterward over another; and
this possibility was one of the considerations leading to an examination i>f
its entire coast line. By that examination it was ascertained that all the
lower passes of tlie basin's rim are at the north, se})arating the basin from the
drainage system of the Columbia River. These passes were systematically
visited by competent observers; and it was ascertained that the Bonneville
waters discharged at one point only.
The trend of the mountain ranges in that region is generally north and
south and the passes are siinjdy culminating points in the intervening valleys.
As a rule they are not rocky, but con.sist of alluvium, the profiles of which
rise gently toward the mountains on either side. South of each sm/h pass
the minor drainage lines from each mountain unite and produce a main
drainafje channel descendino: toward the basin of Great Salt Lake. At tlie
north a similar confluence produces a drainage channel descending toward
the tributaries of the Columbia. On the pass the alluvial profiles from the
mountains unite with gentle curvature; and there is no channel of drainage.
It is a curious fact that in a region characterized by great reliefs of sui--
face, a munber of passes were so nearlv at the same level that a difierence
of only a few feet determined the actual point of discharge. The water of
the lake rose within 75 feet of the pass north of Kelton, where the Boisd
SEARCH FOR THE OUTLET. 173
stage-road crosses from the Salt Lake basin to the head-waters of Raft River;
and it rose Avitliin 100 feet and 200 feet, respectively, of the passes north of
Snowsville and Curlew.
Red Rock pass.-Tlie actual point of discharge was at the north end of Cache
Valley, at a point known as Red Rock Pass; the outflowing river entered
Marsh Creek valley, and being there joined by the Portneuf, flowed through
Portneuf Pass to the valley of the Snake River. The first suggestion of
its position was by Bradle}', who crossed the old channel some miles l)elow
the ])ass in 1872; and it was independently demonstrated l)y Mr. Gilbert
Thompson and by the writer, wlio separately visited the localit-s^ some years
later.^
The ascent to Red Rock l*ass from Cache Valley is so gentle as to be
scarcely noticeable, and the descent on the opposite side, while ]ijerceptible
to the eye, affords an easy grade to the Utah and Northern Railroad. A
few miles west of the pass, there rises a lofty mountain ridge separating
Cache Valley and Marsh Valley from Malade Valley. On the east are
lower mountains, separating Cache Valley and Marsh Valley from Gentile
Valley and Basalt Valley. From the base of the range on either side, an
alluvial slope descends to the pass, but this is not continuous. Knobs of
indurated rock, similar to those constituting the mountain, project through
it, testif}'ing to the existence a short distance beneath the alluvium of a rocky
sj)ur comiecting the two ranges. At a few points there are exposui-es of
less indurated rocks, supposed to be of Tertiary age, but these form no hills
by themselves, being buried under the alluvium except where laid bare by
recent erosion. The alluvium is further interrupted by the clianncl of the
ancient outlet, which is one of the most notable features of the landscape.
It has been excavated to a depth of several hundred feet, and has a general
I It was iiiiiintained by I'eale tliat tlie orii;inal point of discharge was at Portneuf Pass instead of
Red Rock Pass; and the discussion of tliis view gave to the subject of the onth-t and its discovery a,
more voluniiuous literature than perhaps it deserved. The writer's diss nt from Pcale's determination
has already been recorded in discussing the supremacy of the Bonneville shoreline (p. 94). Readers
who care to pursue the subject further will fiud the following references useful :— G. K. Gilber*, in Sur-
veys Wist of the 100th Meridian, vol. 3, Geology, p. 91 : E. E. Howell, idem, p. 'Jr.l ; F. H. Bradley,
Oeol. Survey of Terr., Ann Rept. for 1872, pp. 'JO'^, 20:i ; Gilbert, Bull. Phil. Soc, Washington, vol. 2,
p. 103: A. C. Peale, Geol. Survey of Terrs., Ann. Rept. for 1^~7, pp. 565, 642; Am. Jour. Sci., 3d series,
vol. 15, 1H7H, p. C5; Gilbert, idem, M Series, vol. 15, 1878, p. 256; Peale, idem, vol. 15, 1878, p. 439;
Gilliert, idem, vol. 19, 1880, p. 342; Lieut. Willard Young, Surveys West 100th Meridian, Ann. Rept.
for 1878, n. 121.
174 LAKE BONNEVILLE.
width of about one-third of a mile. Five small streams flow from the
mountains to the ancient channel, and each of these has carved a deep
trench in the alluvium, casting the eroded mateinal into the channel. The
gi-eatest of the streams is Marsh Creek, debouching at Hunt's Ranch; and its
freshly formed deposit occupies the old channel for a distance of nearly three
miles. Three or four miles farther south Five Acre Creek makes a similar
tribute, filling the old channel with alluvium for the space of a mile; and
the same thing is repeated on a smaller scale by Stockton Creek, two miles
farther south. The alluvial fan built by Marsh Creek is a few feet higher
than the others, so that the actiial water parting is at Hunt's Ranch.
Between the Marsh Creek and Five-Acre Creek alluvia, the old chan-
nel is occupied by a marsh three miles in length with an average width of
twelve hundred feet; and Avithin this there is a small pond. Between the
alluvia of Five-Acre Creek and Stockton Creek there is a larger pond, known
as Swan Lake. These marshes and ponds, whenever they accumulate \\ater
enough to overflow, drain sovithward to Cache Valley; and all the streams
of the pass except Marsh Creek are tributary to them. ]\Iarsh Creek turns
abruptly north on entering the channel and flows toward Marsh Valley. Its
volume is so small that during the dry season it does not maintain a super-
ficial flow through the valley, but repeatedly sinks beneath the smface and
reappears below in springs.
The knobs of indurated rock, which in the immediate vicinit}' of the
pass consist of arenaceous limestone, both adjoin and interrupt the chan-
nel. Near Hunt's Ranch there are two buttes, each several hundi-ed feet in
height, overlooking the channel from opposite sides, and between them are
a nmnber of low reefs projecting throvigh the flood-])lain of ]\Iarsli Creek
Constricted by these reefs, the channel has a mininnnn superficial widtli of
only GOO feet.
The relations of these various features will be better imderstood by
reference to the map in PI. XXVKI.
The Bonneville shore-line is traceable continuously about Cache Valley
to the vicinity of the pass. On the east side its most noi'therly vestige is
upon a butte a mile south of Hunt's Ranch. On the west side it is lost on
the alluvial slope two miles from Hunt's Ranch. Its height above the marsh
U S. GEOLOGICAL SURVEY
liAKE BOMNE'/ILLZ, PL Xr^lir
MAP OF THE
OUTLET OF l^VIvE BONNEVILLE
R E D R 0 C Iv P ASS.
Oneida Co Idalio
Toj)Oqraph\ hv h^ J) . John son .
Ofoloqy b\ GK Gilberi
Soiitieiille .S'htwehne
o Vi 1
SCALE I I =4 WILE
3.^'0 iet't (hntoars
ji^^'- ^Oiierrt ^lltwuil Deposits .
.luHus Iticn A t'o.lilli
Di ovm In- G TliompM
RED ItOCK PASS. 175
betAveen Marsh and Five-Acre creeks is 340 feet. The nearest, point at
which the Provo shore-line was observed is about eight niih's farther south,
in the vicinity of the town of Oxfoi'd.
Marsh Creek issues from its canyon in the mountains aljout two and
one-half miles east of the old channel. The intervening' sjjfice is occupied
by a sloping alluvial plain terminating in a bluff. It is evident that this is
an alluvial fan or alluvial cone constructed by the creek before the exca-
vation of the Bonneville outlet. It was afterward partially eroded by the
outflowing river, and also by Marsh Creek, which has excavated a passage
several hundred feet in depth.
Where this old alluvial plain approaches nearest to the Bonneville
channel, its edge is fifty feet higher than the nearest terrace of the Bonne-
ville shore, and a restoration of its profile indicates that it coalesced with
slopes from the opposite mountain range at about the level of the Bonne-
ville shore. A careful study of the ground has satisfied the writer that the
base or outer margin of the alluvial cone was part of the ancient water-
parting, and was the point at which the outflow was initiated.
The fact that the Bonneville water discharged at first over a barrier of
alluvium instead of solid rock had much to do with the subsequent history
of the lake. Uncemented alluvium is easily and rapidly torn up and re-
moved, and as soon as a current began to flow across the divide, it must
have commenced the excavation of a channel. As the channel increased,
the vokime of the escaping water became greater, and this increase of vol-
ume reacted on the power of erosion. In a short time a mighty river was
formed, and the lowering of the lake surface resulted. For a time the out-
pouring was a veritable debacle, and it could not have assumed the phase
of an ordinary river commensurate with the inflow of the lake until the allu-
vial barrier was completely demolished and the resistance of the limestone
reef was called into play. When the corrasion of the channel had proceeded
so far as to give the river a bed of limestone, the process of excavation was
changed from the mere transportation of loose detritus to the corrasion of
solid rock, and the rate of excavation was greatly diminished. We have
here the ex2)lanation of the rajiidity of the final recession of the lake from
the Bonneville level to the Provo.
176 LAKE r.ONNEVlLLE.
Marsh Valley—Marsh Vulk'}', like Cache Valle}', is ench).sed Ijetween mount-
ain ranges, and has a north and south trend. Its length is aljout thirty-five
miles, and its greatest width is eight or ten miles. Twenty miles from Red
Rock Pass, the Portneuf River breaks through the eastern mountain chain
and enters the valley, turning northward and running parallel ^\itli Mai-sh
Creek to the end of the valley. There it receives the creek and then tiii-ns
abruptly westward and escapes from the valley through a deep liut ojx-n
canyon. The upper canyon of the Portneuf has at some time admitted hna
as Avell as water. A succession of basaltic coulees have poured thi-ough it
into Marsh Valley and have followed the slope of the valley to the lower
canyon. The Portneuf River follows the western mai-gin of the lava beds,
and i\Iarsh Creek the eastern, each occu])ying a narrow valley sunk from 'M)
to 100 feet below the level of the lava table. A comparison of these val-
leys illustrates the disparity between Marsh Creek and its channel. I'urt-
neuf River is several times larger than Marsh Creek; l)ut the inuncdiatc
valley liy which it is contained is smaller. Indeed, there is every evidence
that the valley of Marsh Creek, having been formed by the ancient Bonne-
ville river, is now in process of filling. It abounds in meadows and marshes,
and at one point contains a lakelet.
The River.-It a})pears, however, that the Bonneville river was nut citn-
tained during its entire existence in the channel now ((ccuj)ied by Mar.-li
Creek. The whole upper surface of the lava tongue, where it has a width
of more than a mile, is fluted and polished, and pitted with pdt-holes after
the manner nf a river bed; and there seems no escape from the condusidn
that it was swept l)y a broad and rapid current. The trenches at the side
of the lava may or may not then have existed; l)ut even if they did not,
we have to contemplate, as the agent of corrasion, a river comparable with
Niagara. Indeed it is even possibles that Niagara might suifer by com-
parison.
Let us assume that at the time the Bonneville river travtu'sed the la\a-
bed the lower channel at the side had not been eroded; and let us furtlu-r
assume that its width was somewhat less than that of thi' lava, — sa\' one
mile. When the river came into being, the total descent of its bed, from
one end of Marsh Valley to the other, was at the rate of 13 feet to the mile.
THE DEBACLE. 177
In the last stages of its existence its average grade in the same space was 7
feet to the mile. At all stages the declivity was greater near the pass than
in the lower end of Marsh Valley. Let us assume that the slope of the
water surface in flowing over the lava was 2^ feet to tlie mile, or one foot
in 2,000. If now we assume in addition that the discharge equaled that of
the Niagara Rivei', we have all the data necessary for computing the mean
depth; and A\e obtain ftir that depth 9 feet. To one who stands upon the
lava bed and notes the scale of the carvings which ornament its surface,
this determination appears for too small. Twenty feet would better accord
whh the phenomena, and twenty feet woidd discharge the flood volume of
the Missouri.
Another evidence of the magnitude of the outflow is found at the pass.
West of the swamp there is an irregular terrace, extending from Swan Lake
to Red Rock, the upper surface of which is corrugated with parallel furrows
and I'idges trending in the general direction of the current. These consist
partly of limestone crags and partly of alluvium. Comparing them with
similar flutings in other stream beds, they ap^iear to be explicable only as
details of channel-bottom wrought by a torrent of great volume.
How long the discharging river maintained its colossal dimensions can
not be learned, but the period certainly w^as not great. The entire prism of
water between tlie Bonneville and Provo planes would be discharged by
the Niagara channel in less than 25 years; and if the Bonneville river
reached a greater size, it could liave maintained it only for a shorter time.
It is evident that the channel at the pass has been partly filled since
the desiccation of its river; but the precise amount of filling is not so evi-
dent. A crude estimate was based U2)on the configuration of certain small
drainage lines tributary to it. Before the filling began, these drainage lines
(as, for example, that of Gooseberry Creek; see PI. XXVIII) found their
base of erosion in the main channel, and adjusted their profiles thereto.
As the filling of the channel progressed they were likewise partially filled
near their mouths; and a study of their configuration yields a crude esti-
mate of the amomit of deposition. It is judged to be about thirty feet;
and if this estimate is con-ect, the bottom of the channel is 370 feet lower
than the Bonneville shore. This is approximately equal to the difference in
MON I 12
178 LAKE BONNEVILLE.
level of the Bonneville and Provo sliores and it serves to connect the testi-
mony of the outlet with that of the shore-lines.
It is not easy to estimate the cross section of tlic channel of outflow at
any stage of its existence. Undouhtedly it was broader and deeper while
its walls and bed consisted of alluvium than afterward when solid rock was
reached. The trough now occupied by the marshes and Swan Lake i)roba-
bly represents its width after rapid corrasion had ceased ;nid before tJH^ tiiial
desiccation of tlic lake was begun; but this is a mere surmise. We ncc<l not
doubt that it had a greater width at an earlier stage and a less width at a
later.
As the degradation of tiie channel proceeded, the position of its iiead
was continually transferred southward. The discharge was initiated on tlie
Marsh Creek alluvial fan two miles north of Hunt's lianch; but during its
final stages the oiitflowing river headed seven miles farther south, between
Swan Lake ami the Round Valley marsh. When the outflow ceased, the
water parting between the Bonneville and Snake River })asins was r.t tliis
latter })oint, Gooseberry and Five Acre creeks being tributary to the Snake
River. Li the course of time, however, the alluvium de])osited by Marsh
Creek effectually dammed their channel and tui-ned their di'ainage south-
ward. Mar.sh Creek itself must normally alternate in its affiliation. As its
alluvial fan has gradually increased, its debouchure must have been shifted
from Marsh Valley to Cache Valley and vice versa many times. Even now,
in the irrigati(Mi of farming land at Hunt's Ranch, a j)ortion of its water is
sometimes artificially turned toward the Great Basin.
The Gate of Bear River. -Cache Vallcy is Separated from the open l»asin of
Great Salt Lake by a mountain range wliicli at one place is low. Tlirougli
this the Bear River escai)es from the valley by a narrow passage between
precipitous walls of Ihnestone. During the Boimeville epocli the dividing
ridge was submerged at several places, so that the waters of tiie Cache
Valley bay conmuxnicated freely with those of the open lake. During the
Provo epoch the connection was restricted to the ^jassage now occu])ied by
the river, a strait only a f(!W hundred feet broad and a mile and a lialf in
length. One-half of the present water suppl\- of (ireat Salt Lake is derived
from Bear River, and tliat river during the Provo epoch was a tribut^iry of
liii ft
CACHE VALLEY A DISTRIBUTING EESEKVOIK. 179
Cache Bay. Cache Bay therefore presumably received half of the inflow of
tlic Provo lake; aiul it is from Cache Bay that the outflow discharged. If
tlic \()luiue of outflow was greater than the tribute brought by Bear River,
I he difference was supplied by a current from the main lake through the
narrow strait into Cache Bay. If the volume of Bear River was greater than
the outflow, then the excess was discharged througli the strait into the lake.
Doubtless in either case the; flow through the strait was regularly reversed
by reason of the annual inequnlity of the Bear River tribute, and still more
frequently by the eff"ect of storm winds, but if the volume of Bear River
greatly exceeded that of the outflow, it is conceivalile that the fact of out-
fio.v did not imply the perfect freshness of the lake.
This speculation was suggested by a curious piece of negative evidence.
The calcareous tufa which abounds upon the Provo shore has not been found
associated with it in Cache Valley. If it be really absent, and not merely
undetected, its distribution would seem to indicate that, during at least a
large portion of the Provo epoch, the outflow was less than, or did not
greatly exceed, the Bear River inflow. Under such circumstances the main
body may have accumulated carbonate of lime to the point of saturation,
while Cache Bay did not.
The lowering of the lake level by the wear of the outlet diminished the
area of the lake surface about one-third, and it must have diminished the
annual evaporation from the lake surface by about the same amount. Up
to the moment of outflow the entire tribute of the lake was disposed of by
evaporation ; and if the change of climate which brought about the outflow
went no farther, the amount of the discharge during the Provo e})och should
have been one-third of the inflow. It is thus seen to be quite within the range
of possibility that Cache Bay, receiving one-half the total inflow, was a
fresher body of water than the main lake through the entire Provo epoch.
It is certainly most ren:iarkable that a concurrence of geographic and climatic
conditions should enable a lake to maintain a higher degree of salinity than
the water of the outlet limiting its size.
On the other hand, it is not supposable that the main body of Lake
Bonneville was saline, or even brackish, as those terms are ordinarily used,
during the maintenance of the Provo level by outflow. The strait at the
180 LAKE BONNEVILLE.
entrance of Cache Bay was several hundred feet deep, and any sensible
difference in density between the bay and the open lake would luive pro-
duced an interchange of gi-avity currents, the light water flowing from the
bay at the surface, and the dense water entering beneath. Adding to this
regulative action tlie interchange of currents to and fro during storms and
(luring floods, it is evident that only a small difference in the average (con-
stitution of the bay water and the lake water could be maintained. The
very minute difference competent to produce the preci])itation of carbonate
of lime in the open lake would not affect the practical freshness of the water.
It may be remarked in passing that the deposition of tufa during the
Frovo epoch is not inconsistent with a contemporaneous discharge by the lake,
even though Cache Valley did not operate as a distributing reservoir for the
Avater of Bear River. In a broad way, it is true that salt lakes have no dis-
charge, Avhile fresh lakes have, and that lakes are freshened by discharge;
but so long as the volume of outflow is less than the inflow, the freshening
is a matter of degree. The inflowing streams bring a certain amount of
mineral matter; the outlet carries away a certain amount; and as soon as
equilibrium of action is established, these two quantities are equal. If the
volume of the outflow is only a small fraction of the inflow, its salinity must
be greater in inverse ratio: and, since the salinity of the discharge is nor-
mally identical with that of the lake, the latter can not be so pm-e as its
affluents. Carbonate of lime is peculiarly sensitive to the effect of such
conditions. On the one hand, it is dissolved from the rocks by rain and
stream in greater quantity than most other minerals, and on tlie other, its
point of saturation is quickly reached. It might be precipitated in a lake
even while there was free discharge of a third part of the inflowing water.
The Question of an Earlier Discharge.-It liaS beCll SUggCStcd by Davls^ that aUtCrior
to the Bonneville epoch, the altitude of the rim of the basin may have been
such that its drainage was discharged to the ocean without the formation of
a lake, or at least without the formation of a large lake. The more general
problem on which his suggestion bears will be deferred to another chapter;
but it is proper to inquire here whether there is any indication in the rim of the
basin of a pre-Bonneville outflow. The possibility of such an outflow was
_ ' Lake Bonneville [a review], by W. M. Davis: Science, vol. 1, 1883, p. 570.
WAS THERE AN EARLIER OUTLET? 181
fully recognized by the writer during his investigations in the field; and
several of the lower passes were visited with special reference to this ques-
tion. It was not considered important to examine the higher passes, because
displacement of the earth's crust, while paroxysmal in detail, appears in a
broad way to be slowly progressive, so that the time presumably necessary
for lifting a barrier to a considerable height — say one thousand feet — would
suffice for the obliteration by the processes of land sculpture of all traces of
a preexistent channel. The results of the search were purely negative, no
evidence of a pre-Bonneville channel being found. The only poiut where
the indication is not so clear as could be desired is Red Rock Pass. A pre-
Bonneville outlet, occupying" the same position as the Bonneville outlet,
would be very difficult to discover, especially if the intervening period were
sufficient for the accumulation of large bodies of alluvium. Suppose, for
illustration, that Red Rock Pass were to remain subject to the existing con-
ditions until Marsh Creek was enabled to restore the original contours of its
alluvial cone. While the Bonneville channel would be locally filled and
concealed, other portions of it would be likely to remain visilile ; and its
presence would be betrayed by some such phenomenon as Swan Lake.
But if the valley were reflooded and another river traversed the pass, the
washing out of the alluvium would leave a channel practically identical
with the present, and the earlier history would he masked.
If, however, the interval between two discharges sufficed only for the
partial restoration of the alluvial contours, the duplication of the history of
outfiow would be recorded by terraces, and its decipherment would not be
hopeless.^ No such terraces were observed at Red Rock Pass.
These observations manifestly do not warrant the conclusion that tlie
Bonneville basin never had free drainage. They indicate merely that the
last epoch of outflow antecedent to the Bonneville was separated from tlie
latter by so long an interval that the channel of discharge can not now be
discovered.
THE OLD RIVER BED.
The overland stage road which, before the day of Pacific railroads,
carried the mail across the Great Basin, skirted the southern margin of the
Great Salt Lake Desert. From Salt Lake City to Canyon Station, at the
182 LAKE BONNEVILLE.
eastern base of the Deep Creek Mountains, its route lay almost entirely
upon the bed of Lake Bonneville. Midway it crossed a broad channel,
which every one recognized as an ancient river bed. Here a stage station
was established and a change of horses was kept. The horses were not
watered l)y the river, nor even l)y a diminutive modern representative of it,
but by means of a well sunk to a depth of 100 feet. Now that the road
has fallen into disuse and earth has clogged tlie neglected well, the chance
traveller finds nothing to quench his thirst from Simpson spring to Fish
Spring, a distance of 40 miles. One wlio stands here in the midst of a
desert, where the oidy vegetation is a^.scattenng gi-owth of low bushes, and
looks on an ancient river course 2,000 feet broad and more than 100 feet
deep, can not fail to be deeply impressed.
Naturally this old water trace was associated in the minds of observers
with the shore traces on the flanks of the mountains; and it is not surpris-
ing that popular theory located here the outlet of the lake.^ Nevertheless,
the Bonneville shore-line, which is visible upon the adjacent mountains and
buttes, is 700 feet higher than the highest part of the old channel; and our
exploration demonstrated that the entire site of the channel was submerged
during both Bonneville and Provo epochs.
Neither end of the channel is visible from the crossing of the stage
road, but both are commanded by neighboring peaks. It is about 45 miles
in length, and holds a direct course from the heart of the Sevier Desert to
the edge of the Great Salt Lake Desert, passing between the McDowell and
Sunpson Ranges. Throughout its extent it is cut from tlie clays deposited
by the ancient lake. Near the extremities these only are exliibited in its
banks ; but in the middle course, where it follows the base of the McDowell
Mountains and associated buttes, it lays bare the older rocks at several
points. Its general width is about half a mile, lint it expands in places to
nearly a mile, and is elsewhere constricted to about 1,000 feet. At the
south its depth is small, and its southern end is ill defined, the cliannel
features gradually losing themselves in the jdain of tlie Sevier Desert.
Its northern end is more definite, being bordered by low bluffs; and thence
'Seo A. S. Packard in Bull. U. S. Geol. Suiv. Trrr., 2iul 8«ri.w, vol, 1, p. 413 (No. .''>); an.l G. K.
Gilbert, Amer. Jour. Sci., 3(1 nor., vol. 10, 187C, p. 228.
'J S. GEOLOGICAL SUP,VEY
LAKE BOMKE^TLLE. PL.XXXI
Juliua BirnAOu.UUi
DroHTi bv (• Thompsoi
THE OLD RIVER BED. 183
to the River Bed Station its depth increases to 130 feet. In the pass be-
tween the mountains its Ijanks coalesce with the steep faces of huttes; and
its general depth may he several hundred feet.
This description applies merely to its present condition. There is good
reason to holieve that, at the time of its desiccation, it was deeper, especially
in the southern part. Everywhere it is margined by easily eroded lake
sediments; and near the mountains the surfoce of these lies at such an angle
that every rain washes down an abundance of mud into th(^ old channel.
On the Salt Lake Desert the ])lain is so nearly level that superficial waters
have little power of erosion, and the silting of the channel has been less.
In the vicinity of the pass the recent deposit lias a probable depth of 100
to 200 feet.
The general descent of the channel is from south to north, but this
is interrupted at one point in the pass by an alluvial dam, over which the
water seems to find its way rarely. The direction of the original descent, or
the direction of drainage through the channel, is not demonstrated by the
existing levels; but fortunately there is other evidence in the shape of a
terrace, marking a flood-plain of the ancient stream when its channel was
half excavated. This appears on the banks of the channel north of the
River Bed Station, and is capped by a deposit of fine gravel, the pebbles of
which are evidently derived from the McDowell and Simpson Mountains.
From the head of the chamiel the plain of the Sevier Desert descends
southward for many miles; and it is evident that, when the channel was
occupied by a river, the desert was covered by a lake. In a word, the
channel was opened at a time, during the final desiccation of the lake,
when the level of tlie water in the main body fell below the l)ottom of the
strait. The inflow of the Sevier body was for a time greater than its re-
stricted lake surface could discharge by evaporation, and the surplus flowed
over the pass to the main body, opening a channel as it flowed. The upper
lake thus preserved on the Sevier Desert Avas both small and shallow, and
its shore marks have not been identified. The lower lake was large, and
may have left a well marked shore record; but this has not been discrimi-
nated from others on the margin of the desert. A rough estimate, based on
a general knowledge of the contours of the country, indicates that the up-
184 LAKE BONNEVILLE.
per lake had one-eleventli the area of the lower. The lake system had also
another member, for the Bonneville shore had then receded from Utah Val-
ley, and the outlet of Utah Lake was, as now, an affluent of the Great Salt
Lake basin. The continuance of the climatic decadence finally lowered
SeAaer Lake below the level of outflow and dried tlie liver bed.
It has already been remarked that even in the i)ass between the mount-
ains the river bed was carved from the lacustrine strata deposited by Lake
Bonneville. The Bonneville strata there rest against steep faces of the
rocky buttes; and the relation of these faces to each other, and to the gen-
eral course of the channel, indicates that they are the walls of an older
channel whose course the post-Bonneville river followed. The history of
this older channel is unknown ; and its discovery only tells us that, at some
unknoAvn period before the lake, there was free da-ainage from one desert to
the other. Tliere seems no waj^ to determine in which direction this drain-
age led, nor whether either plain was covered by a lake.
OTHER ANCIENT RIVERS. '
•
Three other long abandoned stream courses have been observed within
the basin. One of these has already been mentioned. The pass between
Rush and Tooele valleys is now dammed across by a great system of wave-
built bars, which prevent the drainage of Rush Valley from passing through
Tooele Valley to Great Salt Lake. Against this dam the water of Rush
Valley sometimes accumulates in a lakelet known as Rush Lake, and tliis
lakelet occupies a portion of the ancient drainage channel. It has a width
of 1,000 feet, and is shallow. Doubtless the depth of the channel has been
considerably diminished by recent deposits; and if these were cleared aAvay
the width of its bed would be found smaller than the indication given by
the lake.
This channel is interpreted as showing, not that there was anciently in
Rush Valley a water supply com])etent to override and remove such a liar-
rier as noAV restrains it, but merely that, before the creation of the Bonne-
ville lake, the valley had free drninage northward.
A larger channel, whose habit indicates a stream comparable with the
smaller rivers of the basin, enters Snake Valley from the south at a point
OTHER OLD RIVERS. 185
just east of Wlieeler Peak known as the Snake Valley Settlement. The
channel ends at the margin of the old lake, and appears to have contained
a stream triljutary to the lake, which disappeared at the same time. It is
now occupied near the settlement by a streamlet from the adjacent mount-
ain known as Lake Creek, but this enters the channel at its side, and played
no important jiart in its formation. Above its confluence the channel has
essentially the same dimensions, and these continue as far as it was traced,
about twenty miles from its mouth. Circumstances did not permit its far-
ther exploration.
Near its mouth the ancient stream cut across the base of an immense
alluvial fan, poured out from Wheeler Peak, opening a channel 1,000 feet
broad, which retains a depth of 50 feet. A secondary alluvial fan, formed
by the same mountain stream, and from the material amassed in the first,
was afterwards thrown across the channel, damming it and causing a small
lake. Still more recently this dam was broken through and a smaller chan-
nel Avas opened, whereby the lake was nearly drained, and Lake Creek
escaped to Snake Valley. The closing chapter of the history has been con-
tributed by man. The denizens of the little hamlet have built another dam
within the small channel (a puny and insignificant affair compared with
those of Nature's construction), whereby they have created a pond for the
storage of water for iri'igation.
A third stream course of some magnitude enters the basin in Idaho at
the north end of Snowsville Valley, dc'bouching, fi'om a mountain at the west,
almost precisely at the divide between the drainage of the Basin and that
of the Snake River. It was not traced toward its source, l)ut the grade of
its bed indicates that it drains a valley of some size within the mountains.
Its flood-plain has a breadth, just before it reaches the Bonneville horizon,
of 2,000 feet, and below that liorizon is covered by the lake sediments.
Within the lake area it can be traced for several miles, although lined
throughout by the lacustrine deposits. Through this channel water rarely
finds its way at the present time. The flood-plain is covered by soil and
vegetation, which give no evidence of recent disturbance except along a
narrow meandering- trench that one may leap across. There is here no
delta associated with the Bonneville shore, and the implication seems to be
186 LAKE BONNEVILLE.
that the locality was characterized at tsome very ancient date by a climate
more liumid than either the lionneville or the present.
With tliese exceptions the water courses of the drier coasts are not
known to give evidence of modification. All of them are larger than the
ordinary streams within them require; but the extraordinary requirements
in an arid region are so great that the channels do not seem abiKjnnal.
OUTLETS AND SHORE-LINES.
The harmony between the conclusions based on the phenomena of the
shore-lines and those derived from the features associated with tlie outlet
lias a double bearing. On the one hand, it serves to establish the elements
of the lake's history thus far set forth; and on the other it defines tlu^ in-
fluence of outflow on shore topogra2)hy. Without outflow the level of a
lake is inconstant and oscillatory, and unless the water stands long at the
same level the waves will not excavate cliffs and ten-aces comparable in
magnitude with the embankments constructed.
It follows that the Stansbury shore, which gives e\'idence t)f a perma-
nent water stage, not merely by its cliffs and terraces but by its accumula-
tion of tufa, was determined by an outflow or its equivalent. At one time
I supposed that the problem f»f its existence would be solved by the Old
River Bed — that its level would be found to have been determined by a
discharge from the main Ijody to the Sevier body; but this hypothesis was
was overthrown by the study of the river bed, which showed the discharge
to have been northward instead of southward. The precise relation of the
Stansbury shore to the river bed has not been ascertained, for the shon^ has
not been recognized in that -sdcinity, but they do not differ greatly in alti-
tude. It is probable that during the Stansbury epoch the main lake did
not extend to the Sevier Desert. There is one other valley Avhich might
have served as a reservoir for surplus water at the Stansbury stag(>, Init tlie
connecting strait has not been critically examined. White Valley contained
a large bay during both the Bonneville and Provo epochs, and was deej)
enough to have received a considerable discharge at the Stansl>ury stage, if
the strait was adjusted to its delivery. Its area is indeed small as compared
to the main lake at that level, but it might none the less have served as a
THE STANSBUKY PROBLEM. 187
regulator, causing the oscillating lake to linger at a particular level each
time it rose.
The nature of the problem embodied in the Stansbury shore was not
realized until the field examinations were so nearly complete that the op-
portunity had passed for visiting the localities important for its discussion.
It therefore remains as one of the unanswered questions developed by the
investigation.
CHAPTER V.
THE BONNEVILLE BEDS.
A certain series of lacustrine strata have been designated tlie Bonne-
ville beds. Tlieir relation to the old shore-lines was first pointed out by
Hayden/ and afterward by the geologists of the Fortieth Parallel Siu'vey
and the Wheeler Survey. The grounds for the correlation have not been
distinctly enunciated, probably because they are so patent to each obsers^er
that their statement seems surperfluous. In the present work, however, it
is proposed to combine the history derived from the sediments with the
history derived from the shore record; and there is a logical necessity for
establishing the general synchronism of the two.
A brief account has already been given of the Tertiary lacustrine strata
observed in the Bonneville basin. While these exhibit considerable variety
in texture, they are in general so distinct lithologically from the Bonne^■ille
beds that their discrimination has been easy and uuemban-assed by doubt.
The Bonneville lieds occupy the lowlands, constituting nearly the entire
surface, and retain the attitude of deposition, Ijnng flat on the open plain or
gently inclining at the bases of the mountains. Wherever the outcrops of
the Tertiaiy beds are associated with these, they exhiliit dips referable to
displacement, and they are overlain tuiconformably by the Bonneville. Tlie
Bonneville beds are thus seen to be the latest lacustrine deposit of the basin,
and this fact indicates tlieir synchronism with the latest littoral evidence of
a lacustrine condition.
Again, the distribution of the Bonneville beds is strictly limited l)y the
Bonneville shore-line; and none of the other groups are so limited. The
latter are thus shown to be older than the shore-lines. The Bonne%nlle
' Snn-pictures of Rocky Mountain Scenery, by F. V. Haydeu, New York, 1B70, p. 1S2; Auu.
Kept. Geol. Survey Terr, for 1870, p. 170.
188
COEEELATION OP SEDIMENTS AND SUOKE-LINES. 189
beds are not traceable outward from the center of the basin to all parts of
the Bonneville shore-lines, or at least they do not to that limit hold their
familiar characters; but they bear to the shore-line certain definite relations,
\\liich may be stated. Where the margin of the basin is steep and the
shore-line is high, the lake beds reach to the foot of the slope; where the
basin margin is gently inclined, as in the shallow bays, they extend nearly
to the outer limit of wave work.
Finally, as has been fully set forth by King,' the Bonneville beds are
in places interstratified with alluvial deposits; they rest upon the principal
mass of alluvium from the mountains and support alluvium of recent trans-
portation. Tins relation is strictly paralleled by the shore-lines, which rest
upon the alluvial cones of the mountain bases and are themselves overplaced
by recent alluvium.
Adding to these facts the a priori consideration that the deltas contain
only the coarser material brought by streams, the finer having been car-
ried in suspension to the lake, and that the shore embankments represent
only the coarser part of the product of littoral erosion, the finer having been
carried lakeward by the undertow, so that there must have been fine lake
sediments contemporaneous with the deltas and embankments of the shore,
the general correspondence of the Bonneville beds with the Bonneville
shore-lines is clearly established.
It is only in regard to details that the correlation is less clear than
could be desired. One result of the deposition of the sediments was the
raising of the base level of ex'osion of all streams tributary to the basin, so
as to make them agents of deposition along their lower courses in post-
Bonneville time. The localities are therefore exceedingly rare where even
partial sections of the Bonneville beds can be observed; and it is only at
their extreme outer limits, where they rise toward the shore, that their base
is ever seen.
LOWER RIVER BED SECTION.
The deepest section of the lake beds, or more strictly the section repre-
senting the largest fraction of the Bonneville Period, is exposed in the walls
of the Old River Bed near the point where it is crossed by the Overland
' Geol. 40th Par., vol. 1, p. 493.
190 LAKE BJNNEVILLE.
Stafi;'e-r()ad. It lias some title to be reg'arded as the typical section, and
exhibits tlio following' iriendjers:
1. (At base.) The Yellow Clay, a fine argillaceous deposit, laminated
throughout, olive gray on its fresh exposure, but weathering to a pale yellow.
In this are occasional passages of sand, but these are local and discontin-
uous. Nodules of selenite, consisting of grouped arrow-head crystals, are
abundant; and jointage cracks sometimes contain rosettes of recrystallized
gypsum. Bivalve shells of several species are included. The base is not
seen; a thickness of 90 feet is exposed.
2. The White Marl, a fine calcareous clay or argillaceous marl, light
gray or cream-colored on fresh exposure, nearly white on weathered sur-
face. Contains some gypsum, but less than No. 1. Overlies No. 1 with
unconformity by erosion, and is at its- base crowded with shells represent-
ing nearly the same fauna. Thickness, 10 feet.
3. The marl passes upward into a fine sand, the transition being grad-
ual and the continuity perfect. The sand contains also the same species of
shells. Thickness, about 10 feet, the upper limit being obsciu'ed by a recent
eolian deposit of similar texture.
The distribution of the Yellow Clay and White Marl is universal through-
out the lower parts of the basin, and they ascend in the shallower bays
toward the upper shore-lines. At low levels their physical charactcu-s undergo
little change, and they are readily discriminated by their diff"erence in color.
At very low levels a yellow clay appears over the White Marl, blending
with it as though continuously deposited. This may be the equivalent of
the sandy member in the typi(;al section, which is not everywhere foinid.
The unconformity between the Clay and the Marl does not include any
observed diff"erence in inclination, and is not always detectable, but it was
observed at localities so widely distrilmted as to indicate that it is not a
mere local phenomenon. Against the steeper coasts the beds appear to
terminate somewhat abruptly at low levels; but on gentle slojies they con-
tinue with a change of character, acquiring sand both by admixture and by
intercalation. By these changes their distinctive chai-acters are lost, and at
high levels their separation is for the most part impossible.
THE TYPE SECTION. 191
The exposures of the Yellow Clay are so rare and so small that its
special mutations can not be characterized, but abundant opportiniity is
atlbrded for observation of the White Marl. As the shore is approached, the
arenaceous capping increases in relative thickness, encroaching on the marl
below. The base is the last to change, holding its white color on many
l)arts of the coast to levels above the Provo shore.
At numerous points between the Bomieville and Provo liorizons, sedi-
mentary deposits are seen to alternate with littoral, the former consisting of
marls, clays, and sands, and the latter of shore drift in the form of spits and
bars. We have not succeeded in correlating these sublittoral deposits either
with each other or with the lacustrine sediments of the center of the basin;
and the phenomena, although numerous, are so fragmentary that there seems
no advantage in placing their details on record. Their only contribution to
the deduced history of the lake is the confirmation they afford of the con-
clusion indepeiidently reached that the surface of the lake, when not limited
by outflow, was subject to many minor oscillations.
At a few localities there was observed an abnormal development of the
lacustrine section, a result of what may be called redeposition. A single
illustration will suffice. Snowsville Valley contained at the Bonneville stage
a bay eight miles broad and rumiing twenty miles inland. At the Provo
stage its linear dimensions were reduced one-half, and it became shallow.
At a later and lower stage, possibly the Stansbury, the water barely reached
to the entrance of the bay; and at this time the freshly deposited muds of
the bay appear to have been washed lakeward in great volume, accumulat-
ing at the mouth of the bay in a series of sheets inclined at an angle of 3 or
4 degrees toward the lake. This may perhaps be called a delta deposit, but
it differs from typical deltas in the fineness of its material and the conse-
quent low angle of crosS lamination. The last addition to the deposit con-
stitutes the face of a percejjtible terrace, ascended by the road from Curlew
to Snowsville. Through this terrace Deep Creek or Deseret Creek, the drain
of the valley, has excavated a channel from twenty to thirty feet in depth,
exposing the structure of the mass. The deposit has a general resemblance
to the normal lake beds, but exhibits four or five alternations of the typical
yellow and white colors.
192
LAKE 130NNEV1LLE.
LEMINGTON SECTION.
The uiicniif'orinity of tlio White Marl upon the Yellow Clay iiidieates
(liscoutiimity of lacustrine eouditious; and at two localities this evidence is
supplemented by the occurrence of subaifrial d(;posits at the horizon of un-
conformity. ( )ue of these hjcalities is at Lemin«.^-ton, where the .Sevier River,
issuing from its narrow valley iu the Canyon Range, enters the Sevier
Desert. During the highest water stages, no delta was foi-med at this
point, because the land-locked bay on the east side of th(^ range received
and i-etained all the coarser alluvium; but a great amount of tine matter was
washed into the lake, and this was deposited with exceptional rapidity ;d)(Kit
the mouth of the estuary. The total local deposit must have amounted to
several hundred feet, and recent erosion by the river has exposed 150 feet
of this to view. The point of sj^ecial interest is just outside the canyon
mouth, where the lacustrine strata are seen to abut against the steep face of
Fig. 2h, — Section .showing; snccessiou nf Lacnstriiit* iind Alluvial Ut-posits at Leniini:t«ii. Ut'li.
1. Piilt'ozoic sandstoiKV 2. Tlit! Yellow ('lay (Lower Homieville). 'i. \VtHlj;e of alluvial ;irav«l.
4. The White Marl (Upper IJuuneville). 5. Keceut alluvial j;tavel. G. liuiiiieville shore uutcli, with
recent talus. ,
quartzite constituting the mountain front. The material of the lake beds is
here coarser than in the typical section, and the contrast in color between
the upper and lower series is barely discernible. The Yellow Clay incdudes
through nearly its whole depth a considerable percentage of fine sand, and
the White Marl has a fine texture only at its base, consisting above of coarse
and fine sands.
SECTION ON THE SEVIER RIVER. 193
Associated with the lake beds are two wedges of alluvium, the tliicker
ends of which abut ag,ainst the quartzite of the mountain. The upper of
these is a modern deposit, receiving- additions at every storm; the loAver,
which otherwise is similar in all its characters, is inserted between the White
Marl and the Yellow Clay.
The Marl and its associated sand have here a joint thickness of 50 feet,
and the Yellow Clay a visible thickness of 100 feet, the base being con-
cealed. Tlie Bonneville shore-line, here taking tlie form of a terrace and
clitf, runs 50 feet above the upper limit of the White Marl and 120 feet
above the upper limit of the Yellow Clay.
The series of events by which these relations were produced can not be
mistaken. While the lake stood at a liigli level the Yellow Clay was de-
posited against the base of the mountain; and as the de])osit extends to
within 120 feet of the Bonneville .shore, the lake level must have a])proaclied
this maxiiuimi very nearly. Then the water receded so for as to l)ring sub-
aerial agencies locally into jjlay. The waste from the mountain face was
washed by the rain into the margin of the lacustrine deposit, and accumu-
lated there in a talus or alluvial slope of low inclination. Afterward the
water returned, and remained at a high level during the deposition of the
White Marl; and at the sanae time the Bonneville shore terrace was cut by
the waves.
The locality was carefully studied for the purpose of discovering other
intercalary alluvial wedges, but none were found; and the exposures were
sufficiently complete to warrant the confident assertion that none exist
within the range of the section. Their a])sence indicates that during the
deposition of the visible portion of the lower sedimentary formation the
water did not fall more than 200 feet below the Bonneville horizon, and that
during the period represented by the upper deposit the water did not fall
more than 150 feet below the Bonneville horizon; that is to say, the locality
records twf) high stages of the lake separated by an epoch of lower water,
and [)recludes the hypothesis of a larger number of great oscillations of
water surface within t!ie limits indicated by the local deposits.
MON I 13
194 LAKE BOXNEVILLE.
UPPER RIVER BED SECTION.
The second locality ;it which the clay and marl are separated by sub-
aerial deposits is at the Old River Bed, about five miles south of the point
at which the typical section of the lake deposits was observed. The sedi-
ments here lie about seventy feet higher, rising gradually toward the
mountains and buttes between which the River Bed passes. The numljer
of distinct members in the series is greater than in the northern part of the
River Bed, and the relations are complicated by at lea.st one other uncom-
formity. They are exhibited in the map on PI. XXXII and in the sectional
diagram. Fig. 21). The letters designating formations are made to correspond
in the two illustrations.
Fio. 29.— Tbo Upper Eivir Bod Section; running from AA to Ulf on Pl.ite XXXH.
f7. — Upper Sand. .S"G — .Second Gravel, /y = Lower Sand. If = White Marl. FG ^ First Gravel. 0= Yelliiw
Clay. Vertical .scale greater than horizontal.
On the left or southwest bank of the River Bed, the paleozoic terrane is
largely exposed, consisting of limestones and sandstones or quartzites, be-
lieved to be of Silurian age, though not yielding fossils at this precise point.
The structure of the mass is not essential to the Pleistocene history. On
the opposite side of the River Bed are five small buttes of trachyte and
l)itchstone, nearly buried by the later deposits. These are so ancient and
worn that their forms convey no information as to the original extent of the
masses from wliich they have been carved.
Yellow ciay.-The lowest member of the later series of formations is a fine
laminated clay, which rests-against the Silurian wall on the side of the River
Bed, and presumably surrounds the bases of the buttes, although its contact
is not seen. Tliis is olive on fracture and yellow on weathered surfaces,
and is visil)ly continuous witli tlio Yellow (*hn' of tlic tv])e .sectiim.
First Gravel.- Resting on the clav, with a sliglit uncont'oniiity by erosion,
are several masses of gravel. The largest runs southward from the more
southerly buttes, and has protected the underlying clay from erosion. It is
U S.JEOLCOICAL SUF'/EY
hAl<£ B'jHHE\aLLE PL. XX>II
I c I )?//,.» riav
0 LI) inVER BE D, U TAH
Topo^rn-phy hv W D Johns*
!()- t'i't't CoiKoiLlS
.Iiil.u.H Hicn ^Vo.Uih
Ur.iiwu hv li.TbtimpKf
UPPER RIVER BED SECTION. 195
lenticuliir in cross-section, and has a niaxinmni tliickness of fifty feet. Its
pjbbles are well rounded, and are relatively small at bottom, but at top
include boulders six inches in diameter. Near the surface there is in places
a calcareous cement, binding the pebbles together; and there are also rosettes
or mushroom-like masses of calcareous tufa. The majority of the pebbles
are of pitchstone and trachyte, similar to the material of the adjacent buttes,
but there are also examples of other volcanic nicks not known to occur in
situ within several miles, and also, limestone and ([uartzite, such as constitute
the mountain ranges on both sides and are distributed through all the large
alluvial cones of the neighborhood. At the west margin the mass can be
seen to terminate in a wedge separating the Yellow Cla}' from the next
member of the series, and beyond the limit of the mass there is a ribbon of
sand, witli occasional pebbles, marking its horizon. Half a mile farther west
this ribbon expands into a l)ed of cciarse sand and gravel, four or five feet in
thickness, and half a mile north there is an independent outcrop of similar
material at the same horizon. These masses are not of subaqueous deposi-
tion. The form of the one first described, the associated tufa, and the pre-
ponderance of boulders of local derivation, indicate shore action, but it is
possible that an interlacustrine river was the agent of transportation. What-
ever their origin, the gravels mark a period when the lake level \\as much
lovv-er than during the deposition either of the Yellow Clay or of the suc-
ceeding deposit.
White Marl—Next lu ordcr is a bed of Avhite marl, eight feet in thickness,
deposited uniformly over the undulating surface of the gravel and clay This
is in visible continuity with the White Marl of the type section
Lower sand-Tlic uiarl graduatcs upward into a bed of sand, fine below
and coarse above, with a total de})th of 45 feet. The sand and marl are
conformable throughout, but were both eroded before the deposition of the
next bed.
Second Gravel.- Above tlic saud is a second gravel, which rests unconforma-
bly on the marl as well as the sand, and probably on the first gravel, from
which it could not be separated at the point of contact Its pebbles are
small and are mingled with a coarse sand, the whole having a thickness of
about two feet.
196 LAKE BONNEVILLE.
Upper sand.-Above the secoud jiravel is an up|)t'r bed of sand, conic )rinal)lo
with it so far as conld be ascertained, but exhibitinjj;- little structure. This
has an observed thickness of 32 feet, l)ut may have jj^ained or lost by the
action of the wind, wliich throws its surface into waves, and has ciiused it
to bury at the north the exposure of tlic lower formations.
Upper Gravei.-Finally, tlierc appears about the bases of the more northerly
buttes a fine gravel of alluvial habit. It rests on the second gravel; l)ut its
relation to the upper sand Avas not seen.
On the opposite side of the River Bed there are a few remnants of the
White Marl capping the Yellow Clay; and at one point a small tract of
sand appears, which may belong either to the lower or upper series.
In terms of lake oscillation, this section bears the following interpreta-
tion; first, an epoch of deep submergence, during which the Yellow Clay
was deposited; second, an epoch of emergence, during which the surface of
the Yellow Clay was slightly eroded and the first gravel was deposited,
either by Avave action or by running water; third, a second epoch of deep
submergence, during which the White Marl was thrown down; fourth, a
continuance of submergence, but with a less depth, during the deposition of
the lower sand; fifth, a second epoch of emei'gence, during AA'hich the lower
sand and White Marl were eroded and the second gravel was deposited;
sixth, a third submergence, permitting the accumulation of the upper sand
as a shallow-water deposit; seventh, the final emergence and tlie erosion of
the River Bed. The locality has thus been three times submerged and as
many times laid bare and subjected to atmospheric erosion.
It will be convenient to refer to this locality as the Upper River Bed.
It is coimected by continuous outcrop with th(> Lower River Bed, where
the type section of thc^ lake sediments is exhibited; but there is no such
connection with Lemington, forty miles away. It is al)out sevent}' feet
higher than the Lower River Bed, and about 4r)() feet lower than Lemington.
OSCILIjATIONS of AVATEIl LKTEL,.
At the Lower River Bed locality two emergences are recorded; at
the Upper River Bed, three; at Lemington, two; ;uid it is imjiortant to the
determination of the history of the oscillation that the relations of these
several emergences be ascertained.
COMBINING THE RECORDS. 197
There can l)e no error in referrin<>' tlie latest of tlio indicated emer-
gences at each of the three locaHties to tlie final subsidence of tlie lake a,nd
desiccation of the basin. There were, of course, intervals between the
appearances of the several localities, tlie hig'hest being first exposed by the
receding water, but the existence of these intervals does not contravene the
general fact. We may therefore restrict our attention to the temporary
emergences, of which the Upper River Bed witnessed two and the other
localities one each. Continuity of outcrop demonstrates the identity of the
first emergence at the Upper River Bed with the emergence recorded at the
Lower River Bed; and there is stratigraphic evidence of a cumulative na-
ture in favor of correlating the Lemington emergence with these two. 8ince
this is not direct and positive, it is necessary to state it somewhat fully, in
order to exhibit the weakness of the argument as well as its strength.
The temporary emergence is recorded at the Lower River Bed by an
unconformity — by the erosion of the surface of the Yellow Clay before the
deposition of the White Marl. The section includes in descending order:
(1.) White Marl, crowded with shells at the base; (2.) Unconformity;
(3.) Yellow Clay. All the elements of this section are traceable continu-
ously to the Upper River Bed locality, and they are repeated at several
other localities low down in the basin. A few of these are higher on the
slopes of the basin than the Upper River Bed, and one attains an altitude
of 250 feet above the latter locality, falling only 200 feet short of the Le-
mington locality. The unconformity may therefore be said to have been
traced by a harmonious series of observations within 200 feet of the level
of the Lemington locality. At Lemington the stratigraphic series is com-
parable, but not identical. It contains all the enumerated elements except
the White Marl, and this is replaced by a white clay. On the other hand,
the second emergence recorded at the Upper River Bed has not been recog-
nized elsewhere, so that there is some warrant for the belief that the oscil-
lation of lake surface causing it had not a great amplitude. Finally, the
sediment recording the latest submergence at the Upper River Bed is a sand
merely, indicating that the depth of the water was not great; and if this
submergence did not include the Lemington locality, the preceding emerg-
ence, as recorded at the River Bed, could in no manner be separated, at
Lemington, from the final emergence.
198
LAKE BONNEVILLE.
The accompanying' diagram, Fig. 30, expresses graphically the con-
clusions reached from the joint consideration of tlui threes localities. The
vertical scale represents heiglit of water surface, ranging from tlic level
of Great Salt Lake to that of the Bonneville shore. The horizontal scale
represents (from left to right) the oi-der of sequence, but witlioiit any
attempt to exjjress the relative duration of the several elements of the
UPP£RRIV£RBU
LOWtlililVtnBEl)
Fig. 30. — Diagram ut' Lake Of^cillatiuas uil'enud fium Deposits aod Erosion)'.
history. The curve exhibits the progressive rise and fall of the lake.
Beginning at the left, we have high water represented by the Yellow (Jlay
at all three localities, then an ei)oc]i of low water represented by the allu-
vium at Lemington, by the first gravel at the Upper River Bed, and l)y
unconformity at the Lower River Bed. llow low the water fell, does not
appear. 8o far as this evidence goes, it niay have fallen only to the bottom
of the Old River Bed, or it niay have descended to the level of Great Salt
Lake, or even lower. Then came a second and shorter epoch of deep water,
represented at Lemington by white chu- and sand, nt tlie Tpper River Bed
locality by the White Marl and the lower sand, and at the Lowei- River Bed
by the White Marl. The final emergence is recorded at Lemington by the
superficial alluvium and by the erosion of the modem cliannel of the Sevier
River. Tt is recorded at the Lower River Bed by the erosion of the River
Bed and l)v its ])artial filling with alluvimn. .Vt the Upper River Bed the
THE TWO FLOODS COMPARED. 199
second and third gravels, witli the intervening sand, record a general de-
scent of the water, interrupted by i'n n})ward movement of small extent.
It is not to be understood that this curve exhibits any more of the
historj^ of oscillation than is derivable from the deposits and unconformities
at these three localities. The additional elements derived from the study of
the shore-lines are purposely ignored, and innumerable minor oscillations
are perforce omitted. If sections of all the alluvial, littoral, and lacustrine
deposits of the basin were accessible; and if these were elaborately studied,
it can not ]k' doubted that the simi>le curves here drawn to represent the
two great submergences of the basin would have to be replaced by lines
with innumerable small inflecti(ms, similar to that deduced from the upper
deposits at the Upper River Bed. In the sequel the data embodied in this
curve will be combined with other data in our possession, including that
from the shore-lines and outlet, and a more accurate curve will be drawn.
HEIGHT OF THE FIRST MAXIMUM.
If the first submergence had been carried so far as to produce outflow,
the corrasion of the channel of outflow would have made it impossible for
the second submergence to extend higher than the Provo level. Knowing,
as we do from tlie phenomena of the shores and the features of Red Rock
Pass, that the second submergence was characterized by outflow, we are
warranted in concluding that the first rise was somewhat less tluni tlie sec-
oiul. The amount of tlu* difference appears to be indicated by the embank-
ments of Preuss \alle}', to which allusion has aln^ady been made. At the
north group of embankments, figured in PI. XVI, there is an older series
j)artly buried l)v a newer; and the hig'hest mend^er of this lies 90 feet below
tlie Boimeville horizon. It is probable that this represents the extreme
advance of the earlier flood.
At the Leming-ton locality the Bonneville shore-line is the only one
represented by a sea-clifl" and ten-ace; but at lower levels there are lines
of tufa adhering to tlie (juartzite and apparently marking temporary positions
of the water level. Probably the relation of the waves to the contiguous
slopes enabled them to employ shore drift in attacking the mountain face at
the Bonneville horizon, l)ut did not afford them that aid at lower levels.
200 LAKE BONNEVILLE.
Tlie unarmed waves not only were unable to tear down the cliff, l)ut were
compelled by their peculiar chemical constitution to add a iiiiiici-al cdatino-
to its face. These lines of tufa are all covered l»y tli(! lacustrine deposits
except where exposed by recent denudation; and it is assumed that certain
of them now buried by the White Marl l)eds were formed durin<>- tin- d('])o-
sition of some portion of the Yellow Clay. The ]iiji,liest of tliesc; is se])arated
from the Bonneville shore-line by an interspace of 90 feet (aneroid mea-
surement).
THE WHITENESS OF THE WHITE MARL.
As soon as the wide distribution of the White Marl and the Yellow Clay
and the constancy of their contrast came to be appreciated, attention was
directed to the determination of the cause of their difference. It is easy to
luiderstand a gradation in texture and composition of strata as one passes
from the margin of a, l)asin toward its center, or from the vicinity of sea-
clitfs and river mouths, where the supply of detritus is great, to quieter and
remoter places, reached only by sediment long held in suspension; but it is
not so easy to understand why there should be an abrupt change in the
sedimentary sequence throughout an entire basin. If the true explanation
of the difference between these strata can be reached, it should contribute
something to the history of the lake. For the purpose of seeking such an
explanation, the character of the two deposits has been examined Ixith chem-
icallv and microscopically. Two samples each of the White ]\Iarl and Yel-
low Clay were analyzed by Prof. 0. D. Allen of New Haven, with the
results exhibited in Table III.
CHEMICAL COMPOSITION OF THE CLAY AND THE MARL. 201
Table III. — Jnali/ses of Bonneville Setii,
inents.
I. White Marl from the Ohl River Beii.
n. White M.-111 IVo.u ne.ir Willow SpriuR, .it the eastern h.i30 of the Deep Creek Mouutiins.
III. Upper part of Yellow Clay, Old Kiver Bed.
IV. Lower part of Yellow Clay. Ohl River lied.
lusoluble; percentage
Soluble; percentage
100 parts of the Insoluble portion coutain-
Silica
Aluiuiua
Ferric o.xide
Potaaaa
Soda
Lime
Magnesia
Carbon dioxide
Water .
100 parts of the determined; Soluble constitueut.s eoutaiu-
Sulphiiric oxide
Lime ■
Magnesium
Potash
Soda
Sodium oxide**
Chlorine
Nitric acid**
Boric acid-
Carbonic acid
Lithium
4.5. 03
8.03
2.«5
1.70
.68
19.08
2.71
16.25
2.33
Oxygen equivalent to chlorine.
90.32
23. 539
.916
1 U«
.534
47. 039
96.84
3.16
23. 05
3.20
1.10
.70
.54
3 i. 08
2.87
31.49
1.23
33. 857
tr'ace
trace
trace
20. 204
8.9i;6
.721
1.363
39. 295
Probable couibination of soluble ciuiaJiruents-
Calcium snlphato
Magnesium sulphate
Pota-siuni sulphate
Sodium sulphate
Calcium chloride
Magnesium chloride
Potassium chloride
Sodium chloride
Sodium oxide**
107. 633
7.633
100. 000
2.225
3.444
.987
36. 079
38. 029
trace
III.
0.71
43.84
13.85
4.04
2.40
.44
12.43
4.54
11.88
2.84*
4.111
lY.
100.43
8.806
2.341
5.980
1.792
50. 742
95. 57
4.43
41.74
13.00
3.61
1.87
.70
16.01
4.96
15.78
3.78
100.45
39. 169
present
2.045
4.322
1.897
.370
50. 637
52. 594
Iiresent
108.578 1
8. .578 I
108. 836
8.836
100. 000 I 100. 000
56. 789
1.476
100. 000
21. 775
2.163
2.521
8. .51 1
5.685
8.193
62. 659
2.371
111.865
11.865
100. 000
7.729
2.835
52. 830
22. 728
100. UOO
5.727
3.759
.586
76. 336
10.115
100. 000
* Water lost at 100° C.
t Water lost liy ignition
J The total wei-bt
chloride would be th
tions of the solution.
stitueuts were delerm
por-
con-
♦.„ "The sodium oxide reported among the constituents" is not ass'imed to be free, but to exist as sodium oitrntp
*:i^Ll ",' yi':?."j'_.'T:'» f^^'V" e.'ol' '"Stance; and in the c;,se of the thir.l and fourth' santnles it"anto,,nt' L' c ' »; t^'f:
^^ii^^Ss^^kfsr- '^-'^ --'^^^ '*-«^^- ^^^>^^^^^:^\:'iS'o} ^^:^
202
LAKE BONNEVILLE.
The soluble constituents need not concta-n us at present, for they do
not materially affect the color of the beds. Indeed the characteristic colors
are everywhere recognized by the weathered- surfaces, from which the solu-
ble materials are nearly or completely leached. Tlie carbonic acid in each
of the samples is nearly sufficient to sati.sfy the lime and magnesia; and it
maybe assumed to have been all combined with tliose bases. The alumina,
iron, soda, and the remaining lime and magnesia, undoubtedly exist in the
form of silicates, while the unsatisfied silica is free. The microscopic
characters indicate that the silicates are chiefly feldspars; and if we assume
orthoclase to be predominate, the bases are barely satisfied in the case of
one sample and there i^ an excess of silica in each of the others. It is prob-
able that the following table represents the constitution of the earths nearly
enough for the purposes of the present discussion.
Table IV.— Condensed Results of Analyses in Table III.
Sample
Sample
II.
Sample
III.
Sample
White
Marl:
Mean uf
1 and II.
Yellow
Clay:
Mean of
III and IV.
Carbonates of lime and magnesia- -
Silicates
Per cent.
36
54
10
Per cent.
70
18
12
Per cent.
26
74
0
Percent.
34
62
* 1
Per cent.
53
36
n
Per cent.
30
68
2
Free Silica ,
Totals
100
100
100
100
100
iOO
Under the microscope the White Marl is seen to contain, first, numerous
minute crystals exhibiting double refraction; second, minute particles, ap-
parently clastic, likewise doubly refracting; third, siliceous organisms. The
crystals are too snuill for meiisureinent. They appear in gencrMl to be
taj)ering pyramids whose longer diameters are three or four times their
shorter. They undoubtedly represent the carbonates. The clastic matter
is conceived to represent, in like manner, the silicates, and possil)h- ;i portion
of the free silica. The remainder of the silica, or })ossil)ly th(^ whole of it,
is contained in tlie microscopic organisms. These are ])artly diatoinaceous,
but include also numerous slender tubes witli punctate or jJiipilkite walls
which may be spiculae of sponges.
Unfortunately, a majority of the samples of Yellow Clay which should
have been examined for comparative purposes, were lost in transportation
CARBONATES VERSUS SILICATES. 203
before tlio microscope was applied to them The only two })reserved are
from a subhttoral deposit at Lemingtou and from the type section in the
Old River Bed. These exhibit only rounded grains of crystalline matter,
for the most part clear, uncolored, and doubly refracting-. Neither diatoms
nor cr}'stals were discovered.
In brief, the White Marl and Yellow Clay resemble each other in com-
position, but the former is characterized by a relatively great amount of
earthy carbonates and by free silica, while in the latter the argillaceous
element predominates. In the former the carbonates were largely thrown
down as a chemical precipitate, and St least a portion of the silica is an
organic precipitate. The whiteness of the marl appears to be largely due
to its precipitated elements.
These differences in the characters of the two deposits were unques-
tionably determined by some event in the history of the lake; during the
intervening epoch of low water the conditions of sedimentation underwent
some change. A double interest attaches to the determination f)f the nature
of this change; on the one hand its discovery would add an element to the
history of the lake; and on the other it might lead to the establishment of
some law of sedimentation hitherto unrecognized. Much thought has there-
fore been given to the subject, hypotheses have been framed and many
experiments have been made, but the results of the experiments are unfor-
tunately negative, and the j)i'o]>lem can not be regarded as solvcil. It is
necessary, however, to give some consideration in this place to certain of
the hypotheses for the ])urpose of showing the grounds ujjon which one of
them was so seriously entertained as to receive a provisional jiublication.
SOURCE OF MATERIAL.
The simplest explanation of the change in sedimentation is that the
nature of the material supplied to the lake by tributary streams was for some
reason different. In the interval of time between the two epochs of deposi-
tion, the deformation of the earth's cnist may have wrought changes in the
area of the basin, either cutting off some important element of the detritid
contribution or making some equally inqiortant addition. The prime diffi-
204 LAKE BONNEVILLE.
culty with tliis hypothesis is that the configuration of the region offers no
way of rendering it h)cal and concrete. The calcareous tribute of the basin
must flow chiefly from the limestones of the Wasatch and associated ranges,
and the drainage system by which it is conveyed seems to have been estab-
lished before the Pleistocene. The possibility of an ancient modification in
the drainage system of the Bear River will be discussed in the next chapter;
but such modification, if it occurred, can not have had so late a date as the
epoch of the White Marl.
COMPOSITION OF LAKE WATER.
A second explanation is that the conditions of sedimentation and pre-
cipitation in the basin were ixiodified after the epoch of the Yellow Clay by
a change in the mineral contents of the water of the lake. It is well known
that the precipitation of certain substances from solution is favored by the
presence of certain other substances, and by yet others is retarded. It is
equally well known that the fall of minute suspended particles is similarly
accelerated by the presence of various substances; and their fall is probably
retarded by other substances. Is there any ground for postulating a change
in the mineral contents of the lake which would account for the observed
change in the natui'e of the deposit?
There are three different changes of this sort readily conceived. First,
the water having been relatively pure during the deposition of the Yellow
Clay, it may have acquired, during the interval of recession, a large amount
of mineral matter, so as to be a brine at the time of its second flooding.
Second, the water of tlie first great lake, having been a feeble brine, may
have become so concentrated during the epoch of low water as to precipi-
tate its less hygroscopic minerals, with the result that, when the second fiood
came, a mother liquor was diluted instead of the normal brine. Third, tlie
water of the first great lake, having been a feeble brine, may have been in
the interval not merely concentrated but completely evaporated, the desic-
cation product being mingled with and buried by mechanical sediments, so
as not to be redissolved at the time of the second flood. On the first sup-
position, the White Marl epoch was characterized by a stronger brine than
the Yellow Clay epoch. On the second, it was characterized by the min-
DID THE WATER CnANGE IN COMPOSITION? 205
erals pecular to mother liquors. On the third, it was characterized by purer
water.
Each of these postulated changes may be supposed to have acted in
either of two ways; first, the })eculiar })roperties of the menstruum of the
second flood may have caused the precipitation of an exceptionally large
proportion of the calcareous matter in the center of the basin, and may
have determined the assumption of the crystalline form; second, its prop-
erties may have determined the precipitation of argillaceous sediment near
the shore, thereby diminishing its importance in the center of the basin
and thus increasing the relative percentage of calcareous matter. No at-
tempt has been made to test the first of these assumptions experimentally,
for the reason tliat the natural reactions could not be fairly represented by
the necessarily rapid processes of the laboratory. It may be said, also, that
the assumption is less accordant with what is known of the distribution of
calcareous matter in the basin. From the second point of view a series of
experiments was instituted, the investigation being conducted by my assist-
ant, Mr. I. C. Russell.
Experiments.-In tlic couduct of thcsc experiments no attempt was made to
discuss the general problem of the properties of dissolved substances as the
precipitants of sediments, but attention was confined, to the specific problem
presented by the lake sediments. With the excej)tion of distilled water, the
only materials used were those which occur in the basin and are concerned
with the practical problem. The brine of Great Salt Lake in various stages
of dilution was assumed to represent the water of Lake Bonneville, the
diluent being in each case the approximately fresh water of some stream
now tril)utary to Great Salt Lake and anciently tributary to Lake Bonneville.
The fine sediment employed was a sample of the Yellow Clay. The water
of the selected stream was mixed in various proportions with the Ijrine, and
ecpial quantities of the mixtures were arranged in a series of similar vessels,
tlie pure stream water and pure brine constituting the first and last terms
of the series. Equal portions of the finely divided clay were then added to
each vessel and mingled with the water by shaking or stirring, after which
the vessels were allowed to stand for several days and notes were made of
the relative rates of precipitation.
206 LAKE BONNEVILLE.
The first, streuin water einj)l()yetl was that of City Creek, the sample'
being' <i;'athei-ed at Salt Lake City. The stream is luit lar<;-e, l)ut its sources
lie ainoiii^' rocks typical of the region from which tlie water suj)[)l\' ni' the
basin is derived. ^I'he results were pronounced ;iud apparently unecjuivocal.
Tlie clay fell riipidly in tlie watci- of the creek ;iih1 its dcpositiuii was
indefinitely delayed' in the l)rine, and the vai-ious mixtures <j;;\\v. a graded
series of rates of sedimentation. It seemed evident that a relatively fresh
condition of the ancient lake would favor the rapid precipitation of mechan-
ical sediment, would thus accumulate it close to the shore, and would leave
the calcareous or chemical ]n'ecipitates in relative preponderance near the
center of the Ijasin. Tiie provisional conclusion followed that the cixkIi of
the White Marl was characterized l)y relatively fresh water, and this was
published in a, })reliminary presentation of the investigation.^
It was afterwards learned that the experiments of Ramsey, Brewer, and
others had demonstrated the potency of minute traces of certain suhstnuces
as precipitants of sediment; and it became evident that in order to \-erify
the results of the e.x})eriments with the water of City Creek, it would be
necessary to employ waters representative of a larger share of the su])ply
of the liasin. Samples were accoixlingly obtained from Utah Lake, the ijrin-
ci])al source of the Jordan River, and from the Bear River at Evanston.
Each of these sam[)les represents about one-third of tlie snpplv of (ireat
Salt Lake; and they may fairly l)e assumed to tyi)ifS' tlu^ fVesh-\\ atei- streams
of the basin. Each was subjected to a series of experiments similar tn those
arranged for City Creek water. The sample from ITtah Lake yielded
identical results. With the sample from Bear River the results were dif-
ferent; it was found that the clay was precipitated with espial rapidit\- from
Bear River water, from the brine of Great Salt Lake, and from all luixtiires
of the two. It is evident, therefore, that City Creek watei- is not in this
respect a true representative of the entire fresh-water tribute of the basin;
' It is not to be supposed that the sodium chloride and other mineral constituents of the Salt Lake
hrlae retard the precipitation of sediments. The experiments show merely that they promote it less
than the miner.il constituents of the City Creek water. That tliey actually imimole it, was demon-
strated by coni|>arative experiments witli distilled water. Salt Lake brine and distilled water ai;ree in
retaininrj a residuary milkiuess for an indefinite period, but the approximate clearing of the brine is by
far the more rapid.
'Second Ann. Kept. U. S. Geol. Survey, pp. 177-180
EXPERIMENTS IN SEDIMENTATION.
207
and while the experiments with Bear River water do not negative the theory
broached in the i)reliniinary pubUcation, they serionwly weaken its snpport.
It is a cnrions fact that the City Creek and Utah Lake waters, having
simihxr jn'operties as precipitants, yet diflfer widely in their mineral constit-
uents ; and that the water of Bear River, while behaving very difterently as
a precipitant, yet closely resembles in constitution that of City Creek. The
accompanying table of analyses (Table V.) shows that the water of Utah
Lake is characterized by the sulphate of lime, while the waters of City Creek
and Bear River are characterized by the carbonate.
Table V. Mineral Contents of Fresh Waters in the Salt Lake Basin.
I. Water of City Creek, taken at head of Main .Street, Salt Lake City, December 3(1, 1883.
II. Water of Bear Hirer, taken at Evan.ston, Wyoming.
III. Water of Utah Lake, taken Deeember, 1883.
[t. analyzeil -jy T. M. Chatardi 11 anil III, by F. VV. Clarke.]
Grams to tbe litre.
Per cent, of total solids.
I.
n.
III.
I.
II.
III.
Calcium
.0589
.0174
.0091
. 1280
.0070
.0131
.0010
.0090
. 0432
. 0125
. 0082
. 0982*
.0105
.0049
. 0.-.58
.OIKC
.0178
. 0008*
. 1300
.0124
24.19
7.15
3.74
52. 57
2.87
5.38
0.41
3.69
23.41
6.78
4.44
53.24*
5.09
2.65
18.24
6.08
5.81
19. 88*
42.68
4.04
Snlplmric Acid
Silica
.0070
.0100
3.79
3.27
.2435
.1845
.3060
100. 00
100. 00
100.00
PEOBABLE COMBINATION.
Calcium Carbonate
Magnesium Carbonate
Sodium Carbonate
. 1400
.0606
.0014
.0099
.1080
.0438
.0038
.0644
.0204
.1849
.0204
.0100
57.49
24.88
0.57
4.07
8.87
0.42
3.70
59.20
24.01
1.25
21.19
6.71
60.84
6.71
.0135
.0081
.0070
8.48
4.49
Sodium Chloride
.0216
.0010
.0090
Silica
3.82
3.30
.2435
. 1824 . 3039
100. 00
100. Oil
100.00
"Estimated by difference.
The postulate that the second flood diluted a brine which by fractional
preci})itation had accjuired the character of a* mother liquor, was tested in
the following manner: Samples of the brine of Great Salt Lake were evap-
orated until various portions of the saline contents had been precipitated,
208 LIKE BONNEVILLE.
and tlic residuiu-)- licjuurs were tlien diluted with distilled water and coni-
pared with similar dilutions of the Salt Lake l)riiie. It was found tluit sedi-
ment sejjarated with eijual rapidity from the lirine juid the motlicr liiiuors;
and parallel results were obtained tVom their corresponding derivatives.
The only one, then, of the alternative hyj)otheses suggested above
which tinds any support in the experimental results is the one of wliich pub-
lication has l)een already made, and the support accorded it is insutticient
to inspire confidence. If the water of Bear River instead of City Creek had
l)een first subjected to experiment, the theory would have been at once
abandoned. Nevertheless, since it is not controverted by the experiments,
and since it has practically no competitor, it is proper that its relation to
the general question of lake history be fully set forth.
DEPOSITION BY DESICCATION.
Fully stated, it takes the following form. During the first rise of the
lake, or at least during that part of it represented by the visible portion of
the Yellow Clay, the saline matter was held in solution in such })roportioii
that tlie precipitation of mechanical sediment was slow. The clay intro-
duced by the streams and by the undertow remained in suspension a long
time, and was therefore widely distributed, covering the whole Ixtttom of
the liasin. At tlie close of the Yellow Clay epoch the liasin was completely
desiccated, the saline matter l)eing gathered in the lowest depression and
there precipitated. The raiiifiill of the basin, however, <lid not iliniiiiisii to
absolute zero, and occasional Hoods washed detritus into the (le])ression
containing the salt, until the lattei- was either covered or intermingle(l with
mechanical sediment, and in either case effectually buried. It w;is never
redissolved, and when the increase of the streams caused the basin to be
refiooded, the water of the new lake was almost as fresh as tlie stre;nus. It
had the property of throwing down suspended clay with great i-apidity, so
that tlu^ greater part of the nuid brought to it by the .streams was de|)osited
near th(^ shore, and chemical and organic precij)itates ac(piired relative im-
portance in the center of the l)asin.
It is j)roper to add tliat tiie process of burial by <lesiccation, here
invoked to account for the disappearance of saline matter, is not liv])othetic,
WATER FRESHENED BY DESICCATION. 209
except as regards tlie particular application. It has been full}- demonstrated,
especially by the investigations of Russell/ <^hat it is an actual process, all
stages of which are exhibited in the modern history of the small basins of
Utali nud Nevada. Not only are soluble salts found mingled with the earths
of tlic plavas in all proportions, but crystalline lavers have been discovered
bcncatli eart]i\- })la\a dei)osits; and there are numerous modern lakes of
feeble salinitv occupying closed basins whose upper slopes are covered by
saliferous lacustrine deposits of earlier origin, and whose salts have never
been discharged by means of a lake outlet.
It is an essential part of the hvpothesis that the lake was evaporated
to (Irvness after the deposition of the Yellow Clay; and the establishment
of tlie hvi)0thesis would demonstrate an element of the curve of oscillation
for which there is no other evidence.
ORGANIC REMAINS.
The fossil remains yielded most alntndantly by the Bonneville beds are
tests of fresh-water univalve mollnsks. These are found at all horizons in
the lacustrine deposits, and are likewise imbedded in the tufa, l^hey are
best preserved in the White Marl, and are especially abundant at the base
and the summit of that member. The specimens preserved in the Yellow
Clay are fragile, usually crumbling on exposure to the air, and only in rare
instances washing out so as to be found entire on the siirface. Those at the
base of the White Marl are firm, but of light weight and lusterless, as though
completely despoiled of their organic matter. Those at the top of the Marl,
lying free upon the surface of the desert, are still dense and brilliant, though
completely bleached. They evidently belong to the epoch in which the
lake was finally shrinking.
The first armouncement of these mollusca was by Hayden, who made
a small collection in 1870, publishing an account of it in his annual report
for that year.^ An earlier observation was made by Engelmann in 1859,
but his report remained unpublished luitil 1876.'
' Geological History of Lake Lahontan, pp. 81-86, 224-230.
2U. S. Geol. Survey of Wyoiiiiug, 1870, p. 170.
'Exploratious across the Great Basin of Utah in 1659. Appendix I: Geological Report by
Henry Engelmann, p. 313.
MON I 14
210
LAKE BONNEVILLE.
The list- of species wns soiiifwlint iiicrcMscd liy tlic (■<i]lect,ions Jifterwanl
made by Howell and the writer, and still I'urther additions have been made
by the present Geological Survey. The last and largc^st collection has l)een
studied by Call.' The following list is liascd chieHy oii his dctcnniuations.
List of MoUiisttDi Fo^iftih.
(.'oncIuiV^rs :
Anixlonta iiiif talliana, Lea.
SiiliM^riuiii (lontatuni, Hald.
Aiiuatic gasteropods.
Hi'lisoina trivolvis, Say.
GyrauliiH parvus, Say.
Liiunopbysa paluslris, Miill.
KUMiassi, Bairil.
boiiiievilk'iisis, Call.
desidiosa, Say.
Liinna'a 8tagnalis,Linn.
Physa gyrina, Say.
Aquatic gaHt('r<)|»ods — Conthnifit.
Physa lietci<istr<i|ilia, Say.
lonli, ISainl.
Aniuicola porata, Maid.
cinciniiati'iisiH, Anth.
Fliiiuiiiicola fusca, Hald
Valvata vircns, Tryoii.
sincera, var. iitahensiH, Call.
I'oiiiatiopsis lustiica, Say.
Terrestrial gastcmpoil.
Succinoa liueata, W. G. B.
This list includes but one extinct form, AmuicoJd honneviUensl<t. The
genus Anodonta is represented only by flaky fragments, but the abundance
of A. nuttaUiana in the existing waters of the Great Basin, and its occurrence
in Pleistocene strata in other parts of the Great Basin, render the specific
reference highly probable. Sphcerimn^ Gyraulus, Limncea, Physa, Valvata,
and Succinea were found only on the surface of the desert, but their distri-
bution connects them unmistakably with the ancient lake. The Ostracoda
are represented by a species of Ci/pris, which has been found at A-arions
horizons in the White Marl and Yellow Clay. Its occiuTence is sporadic,
l)ut in a few localities its valves are so abundant as to constitute the entire
mass of certain thin layei's. Diatoms abound in certain portions of the
White Marl, but have not been found in the Yellow Clay. Only a single
occurrence of vegetal matter has been noted; at Lemington, close to the
ancient shore, a stratum of the Yellow Clay contains numerous steins and
roots of a rush, identified by Dr. George Vasey as belonging to the genus
Scirpus.
No mammalian remains of any sort have been obtained from the lake
beds proper, but the alhi\ium of tlu^ deltas has yielded hones at several
I On tliii Quaternary and K.-cmit MoUusca of tlio Great Hasin, I.y 1{. Ellsw.irtli Call: Bull. W S.
Geol. Survey No. II. 1884.
FOSSIL SHELLS. 211
points. Such as have faUen iiii(h'i' tlie writer's oliservatioii nre so poorly
preserved and so t'nvf^mentary as to convey no infornuitiou with rci;;inl to
the species or even ^-I'nera rcjirescnteil. A skull suppos('(l to lia\c been
olitiiincil from ISonncNJllc i;r;i\cls at Salt Lake City, A\'iis idcntH'HMJ hy
1*. A. ( 'hadliourne as helonniuf;' to the Musk ox;' l»ut tlic writer liiis l)een
unahle to satisfy himself as to the precise localit\', ;uid the close juxtapo-
sition of Tertiarv, Pleistocene, and recent strata makes the reference to the
Pleistocene doubtful. Kiny reports the discoverv in ])()st-15onne^'ine gravels
of Bisdi/ latifroHS and hones of reindeer (?);" and elephantine l)ones and
ivory were taken from a post-Bonueville marsh at Springville, near the
eastern shore of Utah Lake.
The meajferness of this record is somewhat remarkable \\h('u we
consider that the lionneville beds constitute the surface of the country
throuyhout nearly the extent of the old lake l)ottoni, and that tlie\' have
been traversed in all directions l)y j^ersons interested in the discoA'cry of
fossils and accustomed to searchin<^ for them. It is evident that the condi-
tions under which the lake beds proper were de])osited were not favorable
for the ])reservation of vertebrates or plants or naiads. We can not believe
that such organisms failed to be received by the lake. The animals which
deposited their bones in the deltas must occasionally have been washed into
deeper water. Driftwood nuist have found its way to the lake bottom, and
fishes and Anodons, AA'liich abound in all the rivers and larger creeks of the
basin, must have inhabited the old lake while it Avas fresh. The fact that
they are not preserved illustrates the fallibility of negative evidence in
paleontology.
JOINT STRUCTURE.
The lower course of the Old River Bed is trenched through beds of
White Marl and Yellow Clay, descending northward with the gentle slope of
their deposition. A few rods back from its edge lies the unfurrowed plain,
but the immediate wall is scul})tured by short gullies alternating with crested
ridges of "bad-land" ty])e. From a commanding peak it was observed that
the trends of the gullies and their branches exhibit parallelism, and the
I Am. Naturalist, vol. 5, p. 315. (Cited from Salt Lake Tribune, May 16, 1871.)
= Geol. Expl. Fortieth Parallel, vol. 1, p. 494.
212 LAKE BONNEVILLE.
cause of this was sought and found by Mr. Russell. They are controlled
by a compound and extensive system of joints.
The principal series trend almost precisely north and soutli, and a sidj-
ordinate series east and west. They all are vertical and strai<j;-lit, and
(within each series) closely parallel. They are readily traced from top to
bottom of the walls of the lateral ravines, and not infrequently a wall
exhibits a broad, flat, sheer face, caused by the removal of the clay from
one side of a plane of jointing. Elsewhere the faces of the bluffs are but-
tressed by square pilasters, or ornamented by outstanding rectangular col-
umns, the forms of which have been determined by the two systems of joints.
The main arroyos leading up from the river bed are controlled by the main
system of joints, but at a short distance back from the bluff there is a trib-
utary drainage at right angles to the primary, and controlled by the cross
joints. The edge of the desert plain is thus marked out in a series of rudely
rectangular blocks, which may be regarded as the incipient stages of the
pilasters of the bluff.
The lamination of the clays and marls in which the joints occur is trace-
able across them, showhig that there have been no faults upon their planes;
and the absence of faults is also attested by the perfect continuity of the
even surface of the plain at a little distance from the river bed.
Mr. Russell's observations showed that the joints are not restricted to
the spot Avhere they Avere first detected, but are discernible generally along
the margin of the river bed. It is impossible to trace them u})on the adj;i-
cent plain, but there can be little doubt that they extend beneath it. The
surface is converted by every shower into a plastic mud, and in that condi-
tion is welded into continuity, obliterating- all trace of structure. For aught
that is known to the contrary, they may exist in the lake beds beneath the
surfnce of the entire desert.
Through the pages of the American Journal of Science,' I called the
attention of geologists to these joints, pointing out that they were not expli-
cable on any existing theory for the origin of such structures. They are not
faults. Their parallelism shows thev are not shrinkage cracks. Travers-
in"- Pleistocene beds that lie unindurated and undisturbed in the attitiule of
I Am. Joiir. Sci., 3(1 series, vol. 23, 1882, pp. 25-27; vol. 24, 1882, pp. r)0-r>3.
POST-BOi^NEVlLLE JOINTS. 213
deposition, they can not have resulted from horizontal pressure and com-
pression. I had no explanation to offer, but my inquiry led to the ]jidjlica-
tion of one so accordant with the phenomena that it at once takes rank as
the working hypothesis for the origin of all ])arallel jointing except slaty
cleavage. It was offered independently by Crosby^ and Walling,^ and the
force appealed to is the earthquake. During the passage of an earthquake
wave the earth material traversed is subjected to momentary strains of com-
pression and tension in the direction of wave transmission, and to shearing
strains, instantly reversed, in a direction normal to that of wave transmission.
At each instant the similar elements of the wave constitute a surface approx-
imately spherical or ellipsoidal, with the locus of wave origin at its center,
and at any locality remote from the locus of origin such surface is sensibly
a vertical plane. Assuming the competence of the strains to create a rock
structure, their directions and arrangement show that the structure should
ordinarily exhibit vertical parallel planes.
Under this theory the two series of joints at the Old River Bed indicate
two earthquake directions and at least two efficient earthquakes. As the
joints extend as simple regular planes to the very margin of the old channel,
and as they determine the directions of arroyos initiated immediately after
the excavation of tlie channel, it is probable that they were formed while
the lake sediments were yet continuous and unchanneled. We are thus told
of eartliquakes occurring just before the retreat of the lake laid bai'e the
White Marl.
That the Bonneville Basin was subject in Bonneville and post-Bonne-
ville time to numerous earthquakes of the type of the great Californiau
earthqiiake of 1872, is abundantly shown by the phenomena of fault scarps
described in Chapter VIII; and the distribution of the fault scarps, so far
a.s it is known, accords well with the strike of the principal system of joints.
' On the classification and origin of joint-structure. By W. O. Crosby. Proc. Boston Soc. Nat.
Hist. vol. 22, 1882, pp. 72-85.
*0n the origin of joint cracks. By H. F. Walling. Am. Ass. Adv. Sci. vol. 31, Montreal meeting,
1882, p. 417.
CHAPTER VI.
THE HISTORY OF THE BONNEVILLE BASIN.
THE PRE-BONNEVIIiliE HISTORY.
The latest Tertiary series outcr()})ping within the Bonneville basin has
a distribution quite independent of the basin. Not only do its strata occiir
in the mountains above the shore-lines, but they override some of the passes
on the rim of the hydi'Ographic basin .and extend continuously to the di'ain-
age of the Snake River, and possibly to that of the Humboldt. On the
other hand, the Neocene strata have not been found in the southern third
of the Bonneville area. It is probable, therefore, that the hydrography of
the Neocene and that of the Pleistocene corresponded to configurations of
the surface essentially different. The Bonneville Basin was not m existence
during the period when the Neocene sediments were deposited; its history
began at some later date, after the deformation of the earth's crust which
elevated the Neocene strata uj)on the mountain flanks had wrought im-
portant changes in the face of the land.
The area formerly covered by the main body of Lake Bonneville is
now a plain, conspicuous for its flatness. Great Salt Lake, i-esting on its
surface, has a mean depth of but fifteen feet; and a rise of a few feet only,
as pointed out by Stansbury, would extend it westward over the greater
portion of what is known as the Great Salt Lake Desert. The (K^currcnce
of such a plain at an elevation of 4000 feet above the sea, and in the midst
of a region characterized by mountains, admits of but one explanation,
namely, lacustrine sedimentation. Th(^ narrow ridges tliat in places inter-
rupt tlie continuity of tlie plain sliow tliat tlie district did not escape the
general process of erogenic corrugation to wliich tlie (Jreat Basin was sub-
214
THE FLATNESS OF THE DESERT. 215
jected, and there seems no reason to believe that the disphiceraents were
here less profound than elsewhere. Certainly the degradation of the sum-
mits has been sufficient to lay bare in places Cambrian and even Archean
i-ocks. Moreover, the habit of these ridges is peculiar, and itself indicates
burial. The normal mountain ridge of the Great Basin is acutely serrate
along its crest, and disjjlays naked rock, deeply carved into gorges and
amphitheaters down to a certain line. Below that line the slopes are
gentler, the contours are smooth, and the material is alluvial, the waste from
the sculpture above. The gorges above and the alluvial cones below
are to a certain extent correlative, but the mass of the latter is derived from
the general degradation of the mountain summit as well as the excavation
of the canyons. The mountains and buttes of the Salt Lake Desert conform
to the Great Basin type in the characters of their summits, but are almost
devoid of alluvial cones. They spring from the plain so abruptly that the
frontiersman as well as the geologist has I'ecognized them as incomplete, or
rather, as partially submerged, and has named them accordingly. One of
them is known as Newfoundland, another as Silver Islet, a third, which
towers 3,000 feet above its base, as Granite Rock; and geuerically they are
spoken of as "lost mountains". How deep beneath the lacustrine ))lain
their bases lie, it is impossible to say, but 2,000 feet is certainly a moderate
estimate.
Not all of this lacustrine filling can be ascribed to the Pleistocene, and
not all of it belongs to tlie history of the Bonneville Basin as such. The
Neocene lake, and possildy earlier lakes, have contributed a sliai-e, and this
before the hydrographic basin of Lake Bonneville was established. Since
the establishment of the basin, sedimentation has been practically continuous
in its lowest depression. If we conceive the local climate to have under-
gone a rliythmic series of clianges, the area of lacustrine sedimentation lias
alternately expanded and coiitracted, and lias always iiududed tlie lowest
depression; and even witli a climate so dry as to maintain no })ereimial
lake, the temporary floods occasioned by exceptional storms must still have
continued the process of accumulation. The situation of the lowest dei)res-
sion may have varied from time to time, as local displacements of the earth's
crust modified the configuration, but wherever it was, it was the scene of
216 LAKE BONNEVILLE.
sedimentation, and the constant tendency of tlie lacustrine process was to
fill the minor depressions and reduce the floor of the basin to a level surface.
The evenness of the desert plain testifies to its lacustrine origin.
Tlic process of filling' might have been modified, but would not have
been interru})ted, by an overflow of the water of the liasin such as occui-red
in the Bonneville epoch. As long as the basin was not drained to its lowest
depths, those depths would continue to receive detrital deposits, and the out-
flowing water would carry with it only the soluble products of the degra-
dation of the surface of the basin. Whether such an overflow ever took
place is not apparent; but if it did, we may l)e sure that its date was remote
as compared to the Bonneville epoch. The lower passes of tlu^ l>asin's rim
show no traces of an ancient channel, and the time necessary for the efface-
ment of such traces must be reckoned as long in comparison to the antiquity
of the Bonneville shore-lines. Upon most of the passes the process would
include the growth of great alluvial fans; and at Red Rock Pass, where the
Bonneville discharge took place, the record of an earlier discharge could
ha^•e been obliterated only by the restoration of the Marsh Creek alluvial
fan, and its extension so as to fill the channel of outflow for many miles in
Marsh Creek Valley. When we consider that no stream so small as Marsh
Creek is known to have built a delta on either the Bonneville or the Provo
shore, it becomes evident that such obliteration implies a period vastly longer
tlian that consumed by the Bonneville oscillations. As far back, then, as we
may hope to obtain a consecutive view of the history of the basin, its waters
had no period < )f discharge save that of the Bonneville epoch. It was a closed
basin, and the area of its lake surface was determined by the relation be-
tween its water supjjly and the rate of evaporation. Tlie lake area was,
therefore, a function of climate, provided the extent of the hydrogra])hic
basin remained unchanged. To avoid any possible misinterpretation of
the climatic historj' it is important that the possibility of variation in the
hydrographic basin receive full attention.
The general altitude of the country to the east of the basin is several
thousand feet greater than that to the west, north and south, and at least 95
per cent, of all the water flowing into the modern lakes is furnished by the
eastern highlands. These include the Wasatch Mountains, a portion of the
ANTIQUITY OF THE BONNEVILLE BASIN. 217
High Plateaus lying to the south, a portion of the Uinta Mountains lying
to the east, and a mountainous tract lying to tlie northeast in western Wyom-
ing and southeastern Idaho. Tlie low country to the west of the basin is
di\idcd l)y mountain ranges into numerous independent drainage districts,
and these have not been so thoroughly studied as to determine what would
be their hydrographic combinations in the event of a more generous rainfall.
We know, however, that they contribute nothing now to the water sup[)ly
of the basin, and that in Bonneville times their tribute was small; and we
are thus assured that in pre-Bonneville times the supply from that side was
not less than at present. It will be shown hereafter that the possibility of a
greater contrilnition from this region does not materially affect the conclu-
sions in regard to climate. The same remarks apply to the region south of
the Escalante Desert. North of the Bonneville Basin the conligurntion of
the country about the water parting does not suggest any possible change
in its position during the period under consideration.
The water supply from the east reaches the lower portions of the basin
by four rivers: the Sevier, the Jordan, the Weber, and the Bear; and its
drainage system is correspondingly divided into four j)arts. The Sevier River
rises in what Button has called the High Plateaus, and is separated by high
divides from the drainage tif the Fremont, tlu- Escalante, the Paria, and the
Virgen, branches of the Colorado of the West. The Paunsagunt and tlie
^larkagunt })lateaus, which constitute the most southerly elements of its
drainage, are slowly diminishing in area through the sapping and recession
of cliffs, and the hydrograjjhic basins of the Paria and Virgen are thus grow-
ing at the expense of the Sevier. A less considerable change of the opposite
tendency is in ])rogress at the head of Moraine Valley, where a plateau
draining to the Fremont River is encroached on by the recession of cliffs
draining to the Sevier. The effect of these slow changes upon the water
sujiply of the Bonneville Basin can not have been important, and there is no
evidence that any considerable tracts have bodily transferred their allegiance.
The Jordan includes among its branches the American Fork, the Provo,
the Spanish Fork, and Salt Creek.
It is quite possible that Salt Creek has changed its course within the
basin, and that it was at one time connected with the Sevier and not per-
218 LAKE BONNEVILLE.
manentlv with tlie Jordiin, ])ut ^uch ;i cliaiige is of no nioiiR'nt in this con-
nection. American Fork and Sjnini.sli Fork head a<^ainst liigh divides, who.se
po.sition must liave l)een permanent for a hmg period. Tlie same remark
ai)pHes to thc^ I'rovo River, but there is one point in its course where its
chainiel is not contained by soHd rock and its water could easily be diverted.
Kamas Prairie is a .small valley lying- athwart the western end of the Finta
Rauffe. The Provo River crosses the southern end of the vallev, enterinjj
by one canyon and leaving by another; and the Weber Riv6r in like manner
crosses its northern end. The configuration of the plain .shows that the
streams have not always been separate; at one time the Provo turned
northward in the valley and was tributary to the Weber. Here, however,
as in the case of Halt Creek, the modifications of the drainage do not affect
tlio water supply of the Bonneville Basin.
The drainage district of the Weber is so nearly embraced at the east
by the basins of the Bear and the Jordan, that the only portion of its
boundary coincident with that of the Bonneville drainage district is a high
crest in the Uinta ^fountains two or three miles in length. Variations in its
course and drainage area are therefore unimportant to the present discus-
sion; and the same remai-k applies to the American Fork and to the series
of creeks issuing from the west face of the Wasatch ]\Ioinitains.
The Bear is the most important of all the rivers, and has many tribu-
taries. Its main brandi lieads in the Uinta Mountains, and, .so far as may
l)e judged from tlu^ maj)s of th(^ Fortieth Parallel Survey, is surrounded by
high divides, affonling little opportunity for tran.snmtations of drainage.
Smith F(jrk and Tliomas Fork, which join it in midcourse, occupy ])asins
contiguous to those of Salt River and John Day River, tributaries to the
Snake. These basins have been mapped by the Geological Survey of the
Territories, and the testimony of the contours is sustained by that of Mr.
Henry Gaimett, who perfonned the topographic work and who states that
the conformation indicates permanence of drahiage. In its lower course
(in ( "aclie Valley) the river receives a large innnl)cr of tributaries, l)ut mtne
of their drainage districts extend to the rim of the Bonneville Basin. The
sources of the river appear thus to offer no suggestion of an ancient variation
of the drainage area; but there is one point in its course of which the same
POSSIBLE CHANGES OF CATCHMENT AREA. 219
can not be said. After receiving the waters of Smith Fork and Thomas
Fork, and before entering Cache Valley, the river swings far to the north,
apiiroaching very near to the rim of the Bonneville Basin. At Soda Springs
it is separated from tlie sonth fork of the lilackfoot River, a l)ninc]i of the
Snake, hy a divide rising fonr or five hnndred feet above the Bear, bnt only
slightly elevated above the Blackfoot. A few miles lower down it crosses
the sonthern end of a broad open valley (IJ5asalt Valley), the northern end
of wliieli is traversed by the Portnenf River, likewise a branch of the Snake.
The Portnenf is here the lower stream, and the water parting between the
two rivers runs close to the course of tlie Bear. It is probably not more
than one or two liundred feet above the bed of the Bear. In the Soda
Springs pass, the sumniit is ftirmcd liy ])asalt, l}ing in horizontal sheets and
associated with cinder cones and other evidence of recent eruption. The
princii)al masses are jjrobably more ancient tliiiu tlie Bonneville epoch, l)ut
they have not suffered those dislocations which are apt to be observed in
this region in the case of rocks dating far back in the Tertiary. It is believed
by Mr. Gannett and by ^\r. Gilbert Thomj)son that their eruption has
affected the drainage system of the region in ways that are yet discernible,
and it is possible that they have wrought a separation of the Blackfoot and
the Bear. If the two streams were anciently united, it is most probable
that the Blackfoot was tril)utary to the Bear; but the reverse is possible.
At the Basalt Valley i)ass the phenomena are essentially the same.
The broad valley extending from the chaimcl oi' tlic Bear to that of the
Portnenf is covered throughout by basaltic la\a, and portions of this lava
are so recent that associated scoriaceous craters are still preserved. Befoi-e
the epoch of eruption, the Bear and Portnenf Rivers may have been joined,
and their united water may have flowed either to the Snake River or to the
Bonneville Basin.
If the south fork of the Blackfoot were uo\\ to be diverted to the valley
of the Bear River, as, according to Mr. Thompson, it readily might be, the
Salt Lake drainage basin would be increased by 350 square miles of upland.
If the canyon of the Portnenf below Basalt Valley were dammed, so as to
turn its water toward Bear River, 500 square miles would be added to the
basin. If another eriq)tion were to dam Bear River aljove Gentile Valley
220 LAKE BONNEVILLE.
and divert it to tlie v;vlloy of the Portnenf, the Bonneville Basin would lose
about one-fourth of its water supply. All speculation in rejj^ard to the pre-
Bonneville climate of the l)asin is therefore subject to the possi])ility that
the catchment basin niay on the one hand have been sliyhtly greater or
may on the other have been very materially less.
ALLUVIAL CONES AND ARIDITY.
The principnl evidence bearing on the pre-Bonneville history of the
l)asin is embodied in the alluvial cones. These extend nearly to the l^ottom
of the basin, and since they could not have been shaped in the pi*esence of
a large lake, it is concluded that the epoch of their formation was an epocii
of low water. The dependent conclusion that the pre-Bonneville ei)ocli
was characterized by aridity is of such importance that a little space Avill
be de^•oted to the amplification of these propositions.
'V\n' drainage of a mountain mass, starting in innumerable rills, gathers
into a smaller number of rivulets, and is finally aggregated into a verv few
main streams before issuing from its self-carved gorges. The outward borne
detritus is therefore delivered to the adjacent valley at a limited number of
points separated by interspaces. Each point of issue becomes the apex of
a sloping mass of alluvium whose surface inclines equably in all directions.
A series of such alluvial cones is usually to be found along the base of
each mountain range, constituting a foot slope, the contours of which are
scalloped. The topographic configuration which thus arises is peculiar and
not liable to be confounded with any other.
It has already been stated that the alluvial bases of the insular mount-
ains of the Bonneville Basin are buried by lacustrine sediments. Those of
the peripheral mountains are not so buried, or at least are not so dee})ly
buried, and the forms of their cones can at many localities be traced down-
ward to the lower levels of the basin. The shore-lines are locall\- mai-kcd
upon the cones, cliffs and terraces being excavated from them and ciuhaiik-
ments built against them; but where the cones are large, these modifica-
tions are relativelv small ;ind do not materialh- impair the general con-
figuration. Good illustrations are to be found in i'reuss Valley, in White
Valley, at the eastern base o( the Deep Creek and Gosiute Mountains, and
DRY CLIMATE BEFORE LAKE EPOCH. 221
on 1 )()th sides of Pilot Creek. There are fine examples also in Tooele Valley,
Skull Valley and Blue Creek Valley.
The phenomena of the Bonneville shores illustrate the fact that the
buildinji- of alluvial cones is arrested by lacustrine conditions. p]ither the
stream constructs a delta, which is an alluvial fan above the water but ter-
minates in a submerged cliff at the water edye; or else, the stream being
small, its load of detritus is absorbed by the shore drift. In the latter case,
some point of the alluvial cone is usually trenched on by the waves, a cliff
and terrace being jjroduced; and whenever the stream, which had ])reviously
shifted its course over the whole surfiice of the cone, assumes a direction
leading to this cliff, it is enabled })y the lowering of its l^ase level to exca-
vate a more permanent channel, from which it does not quickly escape.
It is therefore leg-itimate to reg'ard the formation of alluvial cones as a
stiictly subaerial process, and to conclude that the Bonne\ille Basin con-
tained no large lake during the pre-Bonneville period when its alluvial cones
were formed.
I do not overlook the possibility that traces of an epoch Avlien the
waves held sway may have been obliterated by the alluviation of a later
epoch, but in my judgment such considerations do not impair the general
conclusion. Within the masses of the alluvial cones there niay be liuried
shore cliffs, shore embankments, and lacustrine sediments, but the time
necessary for the oliliteration in this nuiuner of a record similar to that of
the Bonneville lake is as long as tlie time necessary for the obliteration of
a channel of outflow, and is certainly very long as compared to the dura-
tion of the Bonneville epoch.
Let us call this relatively long epoch antecedent to the Bonneville, the
pre-Bonneville epoch. We have found reason to believe, first, that the
basin had then no outlet, and, second, that the basin did not then contain
a large lake. The size of an inclosed lake being determined l)y the ratio of
water supply to rate of evaporation, it follows that that ratio was small. If
the hydrographic area remained unchanged, the water supply as well as tlie
rate of evaporation depended upon climate, and tlie climate must have been
arid. If the main branch of Bear River was then tributary to the Portneuf
Basin instead of the Bonneville, a greater climatic change would have been
222 LAKE BONNEVILLE.
necessary to flood the basin, and the hidicated aridity of climate is corre-
spondingly less.
THE POST-BONNEVILLB HISTORY.
l^lie closiu'i' event of the Hoiiiicn illc liist(ii'\' \v;is the (Icsiccatioii uf the
basin. \ ft'W stii<i'{'s in tlm retiiX'inciit ut the water are rcc()r(ic(l \)\ tiie
Stansl)ury and lower shore-lines, bnt xi-vy little information is dbtainable in
regard to the oscillations which may have interru})ted the retirement, for
the reason that no natui-al sections of the deposits exist. If oscillations took
place they nuist have wrought the superposition of littoral and subacpieous
dejjosits, but the record of such superposition can be read only when new
general conditions shall have exposed thi' lower reaches of the l)asiu to
stream erosion.
SUBDIVISION OF THE BASIN.
One effect of the desiccation was the subdivision of the Bonneville
Basin. Not merely was the Sevier Desert set off from the basin of (Jreat
Salt Lake, but a numbcn- of smaller basins became equally distinct, 'i'he list
of independent drainage districts includes at the present time the Escalante
Desert, the Sevier Desert, Preuss Valley, White Valley, Snake Valley from
the Salt Marsh southward. Rush Valley, Cedar Valley, the u))per portion of
Pocatello Valley, the Pilot Peak basin, and the basin of Great Salt Lake.
It is possible that Snake Valley contains two drainage basins instead of one,
and there is some reason also to suppose that the broad expanse of the Great
Salt Lake Desert west of the Cedar Range is a distinct basin. The mutual
relations and the relative size of these basins are shown in PI. XII.
Three of them contain, (.)r are known to have contained, perennial lakes;
the others have playas in their lowest depressions, where water gathers
after every storm but does not persist throughout the year. On the Great
Salt Lake Desert the earth constituting the playa is exceedingly fine and
affords in dry weather a hard sui-fiice of a pale yellow color. In ))laces, and
especially toward the margins of the area, it is less compact, and is super-
ficially covered witli saline efflorescence. A little i-ain renders the surface
soft and adhesive, and the depth to which tliis change may extend seems
limited only by the supply of moisture. The same description ajiplies to
Preuss Valley, White Valley, and the Escalante Desert, except that the
DUNES OF GYPSUM. 223
playas of tlio Inst two are less compart. The Pilot Peak l);isiii lies south-
east of that mountain, and is separated trom tlie Great Salt Lake Desert by
the rang-e kn()\\'n as tlie Desert Hills. The surface of its playa was found
by 8t;uisbury to be covered by one or two inches of salt. In the south-
eastern ani^'le of the Sevier Desert there is a tract jiartially partiti(tned fi-om
the pft'iieral plain by a series of coulees of ))asaltic lava, extravasated during-
the Bonneville epoch. This contains several playas, marking localities where
the drainage is checked but not completely imprisoned. The highest and
most southerly of these differs from all the others in that its material is gyp-
sum. It is probable that the deposit is independent of any special chemical
reaction, and is due simply to the discharge by evaporation of a mineral
dissolved from the rocks. The streams whose waters occasionally flood the
playa rise among strata of Jurassic and Triassic age, and such strata in a
neighboring mountain range are kno^vn to be highly gypsiferous. The
heads of the streams were not examined. It was ascertained by digging in
the playa that a portion of the deposit is amorphous and another portion
crystalline. One phase of the precipitation results in the formation of small
free crystals, which the wind sweeps from the surface of the playa and
gathers in dunes. The dunes do not travel to a great distance, but are
an-ested by a low rhyolitic butte near by, to which they have given the
name of White Mountain. Perhaps no gypsum deposit in the world is so
easily exploited as this; it needs merely to be shoveled into wagons and
hauled away. Mr. Russell estimates that the dunes contain about 450,000
tons, and a much larger amount can be obtained from the playa The
depth of the playa deposit was not ascertained, but its area is indicated on
PI. XXXV.
SNAKE VALLEY SALT MARSH.
The lowest depression in the Snake Valley Basin contains what is
locall}' known as a salt marsh; but the term as here used denotes something
very different from the salt marsh of the seashore. There is no vegetation,
but simply a shallow lake, which nearl)- or quite disappears in summer. In
winter it has a depth of about two feet, being then limpid and resting on a
bed of soft mud. Near the lake are perennial fresh springs which replenish
the water lost by evaporation. In winter, when evaporation is slow, the
224 LAKE BONNEVILLE.
volume of the lake increases, and salts ])reviously precipitated are redis-
sdlvcd. in siiiiuHer a more rapid evaporation diminishes the volume, pre-
(■ipitatin<i' sodium chloride and sodium sulphate and rcduciiiii' the brine to a
mother litpior. The precipitate has a depth of ahout \ h im-lies, and a por-
tion of it is each yaw removed, to he employed as ii reji^'eiit in tlie reihic-
tion of silver ore. 1'liis i-emoval has not been found to aft'ect juateriallv tlie
strennth of the brine, which is in some Avay resu])plied with salt.' It is
believed by Mr. W. (J. Barry, one of the owners of the marsh, that the
suppl}' is brought by percolating water from the saliferous mud beneath the
lake, and this tlieory of its origin tinds support in the phenomena of a series
f salt marshes in Nevada examined by Mr. Russell.
o
a
SEVIER LAKE.
The lowest depression of the Sevier Desert has probably been occu-
pied l)y a lake from the date of the earliest exploration nearly to the present
time, but i)recise information in regard to it dates from 1872. Escalante in
177n crossed the Sevier river sixty or seventy miles from the lake, and
leai-ned by report of its existence. Fremont did the same in liS4r). In
1853 Gunnison was killed by Indians within a few miles of the lake while
on his way to explore it.^ lieckwith and Simpson, who conducted explo-
rations in contiguous portions of the Great liasin in IS'),'! and IS.")!), were
aware of its existence, but saw it onh from a distance.^ In 18()9 Wheeler,
jiproachingfrom the west, visited the south end of the lake and determined
its true position, lie was unaware of its identity, however, and, following
an error prevalent at that time, called it Preuss Lake.* It was reserved foi
' The stateiiioiits regarding this iiiarNli arc cliieHy based on observations made in tin' winter of
187y-'80.
-Report by Lient. 10. O. Heeknitb, n|>on the route near Uie :?Stli and li'.Uli parallels, explored by
Capt. J. W. Gnnnison : I'acilie lvailroa<l Explorations, vol. 2, pp. 72-74.
■■Capt. J. H. Simpson, Exidorations aiToss the Great Ba.sin. etc., p. I'i't; Licnt. E. G. Reckwitb,
Ibid., pp. 72, 76.
■•See pages 3 and 4 of the Preliminary Report of the General Features of the Military Reeon-
naisance throngh Southern Nevada [18(19] under Lient. George M. Wheeler. 8". [No imprint nor
date, bnt probably San Francisco, 1870.] This report was reprinted in (jnarto form with some changes
in 187.'). The map prepared to accompany it marks " Prenss Lake '" in the geograjjhic position of Seviir
Lake. The edition of the U. S. Engineer map of the Western Territorit^s <latoil 18li8 gives Sevier and
Preuss as separate lakes, and most privately piiblisUed ma |)s follow it, lint a map cd' Coltoli's dated
1864 gives Sevier Lake only, ruuniug into it the river with which imagination had furuished Preuss
Lake.
EXl'LOiiATlON OF SEVIER LAKE. 225
Lieut. R. L. Hoxie, linving charge in 1872 of one of tlie field parties of tlie
Wheeler Survey, to demonstrate the full hydrography of the lake, determin-
ing its form and extent and its relation to the tributary stream. The map
prepar<'<l l)y his topogra])]ier, Mr. Louis Nell, is copied in all modern com-
])ilatious. The writer had the jjleasure to accompany Lieut. Hoxie, and
has since revisited the locality. Li 1872 the lake was about 28 miles in
length and had a water sui"f;ice of 188 square miles. It has since been
ascertained that its maxiiiiuin (lei)tli was about 15 feet, the northern portion
being deeper than the southern. Its <»nly affluent was tlie Sevier River,
which entered at the north. Its l)rine contained <S.(!4 per cent of saline
matter, consisting chiefly of sodium chloride and sodiiun sulphate.
Salt Bed-In January, 1880, the bed of the lake was nearly dry, and was
explored by Mr. Willard I). Johnson, who was able to travel on foot across
a bed of salt where the water had before been deepest. In places this bed
was covered by a thin sheet of bitter water, but elsewhere its surface was
dry. It was rej)orted by persons resident in the vicinity that in the fall of
the year the entire area had been dry, and that this condition had been
attained by the lake basin during one or two })receding seasons. On the
2()th of August, the same year, Mr. Russell and I visited the locality, but
the condition of tlie crust of salt did not permit us to cross it. It had prob-
ably, in the interval, ])eeu partially or wholly redissolved and redeposited;
and its new state of aggregation was less compact.
Mr. Johnson cut through the salt layer at several points, finding a
general thickness of four or five inches; and he collected samples near the
center of the area. Another series of samples was collected by Mr. Russell
at the margin of the area; and at each point the underlying sediments were
explored to a depth of a few feet. The following are the recorded sections:
Section at center of Sevier Lake salt bat, January, 1880.
1. (Top). Sodiiiiii sulphate, 2 inches.
2. Sodiuiii sulphate with some sodium chloride ; coherent to No. 1 : 1 inch.
15. Sodium sulphate, tinged with pink, 2 inches.
4. Gray clay containing woody fil>re, 2 inches.
5. Fine sand containing fresh water shells, 6 inches.
6. Gray clay.
MON I 15
226
LAKE BONNEVILLE.
Section at margin of Sevier Lake salt bed, Anguat 20, 1880.
1. (Top). Sixliiim chloriilo, foriiiiiij; a colicroiit crust : i inoli.
'.;. Soiliiiin chloride, with Hodiiim 8uli)hato and magnesium sulpbato; free crystals luiugled with
water: li iuclies.
:!. Sodium siilph.ate, witli sodium chloride ; a crust of coherent crystals: i inch.
4. Sodium chloride, with magnesium sulphate; incoherent crystals mingled with water: IJ
inches.
C>. Sodium chloride, with sodium sulphate, cliemii-ally identical with No. 2 hut (ine-Kraim-d and
with the consistence of an ooze; color white above with occasional passages of pink, green heueath:
i inch.
(). Dark gray mud : 2 feet.
Tlie sulijoined table of" analyses exlii1)its in detail the constitution of
the saline de})osits in each section, and the composition of the original brine
is added for comparison. The con-
spicuous fact is that the sodium sul-
pliate is concentrated in the middle
(if the basin, while the sodium chlo-
ride is chiefly deposited at the mar-
gin. The sulphates of magnesium
and potassium likewise occur exclu-
sively at the margin. It is note-
\\(»rthy also that magnesium is re-
ported in larger proportion in the
Ijrine of the lake than in any layer
of the desiccation products at either
point of determination. The mag-
nesium chloride reported in the brine
implies three per cent, of magnesium.
The magnesium sulphate in the
richest layer of the desiccation prod-
FlG. 31.— Sevi.r L,iko in 1873 (Nell). The white areas uct impHeS Oldy 1.7 per Ceut. of
with dotted biniuduriu.s show ealt bods in 1880 (JoIidbou).
magnesium.
The brine of the lake was analyzed by Dr. Oscar Loew; the desicca-
tion products from the center of the area by Prof S. A. Lattimore; those
fit mi tlie margin by Prof O. D. Allen. The brine contained 8.G4 per cent,
of saline matter; the constituents are here reported in percentages of total
solid matter. The constituents of the desiccation products are likewise
DRYING OF SEVIEK LAKE.
227
reported in percentages. The figures for tlu^ total deposit are obtained by
combining tliose of tlie separate layers, making allowani'e for n^lative
thickness.
A few weeks after our oljservation of tlie salt bed, Mr. Uusscll and I
separately visited the southern portion <if tlie lake bottom, where the water
had been comparatively shallow. Near the old shore, and especially at the
extreme southern end, the b<»tt(»m had the ordinary [)laya character, a fine
earth, highly charged with salt, for the most part firmly compacted, but in
places softened l)y efflorescence. Farther from shore a thin crust of salt
rested on a saline nnul, and at the outermost point reached by Mr. Russell
the superficial salt deposit had a thickness of 1-^ inches, consisting chiefly of
a moist, incoherent aggregation of crystals. Beneath this were greenish
mud and sand.
Table VI. Analyses of Sevier Lake DesiccaHon Products and Brine.
CoDstitiients.
Desiccation Products at Center.
Desiccatiou Products at
Margin.
Solid
contents
of Brine.
Upper
lajer.
Second
layei .
Third
layer.
Total.
Upper
la> er.
Second
layer.
Third
layer.
Fourth
layer.
Fifth
layer.
Total.
Sodinm Sulphate
Sodium Carbonate
Sodinm Chloride
Calcium Sulphate
Ma^nesiun) Sulphate ..
Ma^ueBium Clilorido ..
87.65
1.08
2.34
trace
trace
71.23
89.10
84.6
.4
7.0
4.78
5.51
83.79
2.71
5.04
14.3
15.5
23.86
trace
trace
2.65
91.39
trace
1.83
79.86
7.83
13.84
trace
1.33
88.49
5.29
80.62
.39-
8.32
75.8
5.5
72.1
.5
11.9
Potassium Sulphate . . .
trace
.34
.26
.11
4.03
trace
trace
.92
.68
.7
Boric Acid
Water
8.90
trace
4.90
trace
8.20
trace
8.0
2.00
6.46
.78
3.40
3.6
.1
Total ...
99.97
99.08
99.95
100.0
100, 00
100.00
100. 00
100.00
100. 00
100. 00
100. 00
The desiccation of this lake is to be ascribed to human agency. The
water of its sole tributary flows for nearly 200 miles through valleys con-
taining more or less arable land, and has gradually been monopolized by
the agriculturist for the purpose of irrigation. The supply is however not
completely cut off. It is reported that during the spring freshets, caused by
the melting of the snow on the plateaus and mountains, the lake bottom
receives considerable inflow, and that the desiccated condition obtains dur-
ing only a portion of the year.
The principal salt deposit was estimated to extend eight miles north
and south and to have an extreme width of about five miles. The accom-
228 LAKE BONNEVILLE.
panying sketch shows the form and area of the lake iu 1872 and the
approximate extent and position of the salt beds iu 1880.
RUSH LAKE.
The lowest depression of Rush Valley contains a pond or lakelet which
has been observed to undergo considerable fluctuation. It will be recalled
that Rush Valley in pre-Bonneville time drained freely to Tooele Valley
and that this drainage was cut off by an embankment built by the Bonne-
ville waves. The lake occupies a portion of the old drainage channel close
to the embankment. It is partially delineated in the map on PI. XX. The
earliest record of it appears on Stansbury's map (1850)/ but it is not men-
tioned in his text. It is there assigned a length of about 1^ miles, but there
is circumstantial evidence that no measurement was made. In 1 855 it was
included in a military reservation laid out by Lieut. Col. E. J. Steptoe for
the purpose of securing to the military post at Camp Floyd the meadow and
pasturage about the lake shore. The map made for the purpose of defining
the reservation, assigned to the lake a length of 2| miles, and indicated that
the water was shallow and marshy. The land surveys in the valley in
1856 did not include the military reservation, but showed the existence upon
it of a lake. According to Gen. P. E. Connor, who succeeded Col. Steptoe
in 18G2, there was then only a small pond, the remainder of the lake bed
being occupied by meadow land. In 18G5 the water began to increase, the
greatest height being attained in 187G or 1877, since which time it has sub-
sided. The rise of the water submerged the meadow land and rendered
the reservation useless for its original purpose. It was therefore ofticially
relinf[uished by the War Department in 1869.
In 1872, the water being near its highest stage, the lake was surveyed
in connection with the surrounding country by one of the parties of the
Wheeler Survey, and the length was determined to be 4^ miles.
In 1880, Avhen the lake was visited by the writer, it was said l)y residents
to have shrunken to half its ninximuni size. The position of the highest
' Expl. ami Siirv. V;i]lc<y of the Groat Sail Lake of Utah. By Howard Stausbury, Capt. Corns
Topof,'. ling., U. S. A. I'hilaclclphia, 1852.
FRESBNESS OF RUSH LAKE. 229
shore-line was not pointed out, but it is believed to be represented at the
north end by a fresh looking beach, not yet covered by vegetation. Tliis
beach had a lieight above the water surface of 10 feet. The greatest depth
of the water was ascertained to be 5^ feet.
At no time does the lake appear to have been strongly saline. Diu-ing
its highest stage it was so fresh as to serve not only for the watering of
stock but for domestic use; and in 1880 it was far from being undrinkable,
though too brackish to be palatable. Its mineral contents, judged by the
taste, did not exceed one-half of one per cent. This freshness stands in
strong contrast to the salinity of the Snake Valley salt marsh and Sevier
Lake, yet the conditions are in most respects nearly identical. Each of the
three lakes is the evaporating pan for a closed basin; and each basin in-
cludes a valley plain sheeted with Bonneville sediments, everywhere more
or less saliferous. The salinity of Sevier Lake and the salt marsh is thus
easily accounted for, and only the freshness of Rush Lake is problematic. I
conceive that the true explanation lies in the hypothesis of burial by desic-
cation, already advanced to account for an element of the Bonneville history.
At some period, or at several different periods, the lake has evaporated to
dryness; and its saline matter being thus precipitated has become buried
beneath mechanical sediment. The last period of this kind was so recent
that the subsequent accumulation of saline matter has not given a briny
character to the water.
If this hypothesis is true, then Sevier Lake, having by the settlement
of the Sevier Valley been changed from a perennial lake to an occasional
lake or playa lake, should in the course of time lose its saline character.
Every freshet of the Sevier River which carries niechanical sediment to the
lake but does not pour into it a sufficient body of water to redissolve the
precipitated salt, must mingle -with that salt a certain amount of silt, and
the continuance of the process will have the effect of obstructing and finally
of preventing the access of the water to the salt. The lake liottom will then
be reduced to the condition of an ordinary playa, and should some political
or industrial revolution afterward stop the work of irrigation in the ■salley
of the Sevier and permit the lake to be restored, the water of the lake will
at first be fresh.
230 LAKE BONNEVILLE.
GREAT SALT LAKE.
The present investigation has added Httle to our knowledge of Great
Salt Lake. It Avas part of the original plan to give to it a somewhat elal)-
orate study, ascertaining the distribution of high and low salinity within its
area, the nature of the deposits formed in various parts of its bed, and the
economic properties of its brine. It was proposed also to make a thorough
survey of its bottom, so as to ascertain the presence or absence of sul)merged
shore-lines and jjlayas. These inquiries, having been deferred until the end
of the Bonneville investigation proper, were necessarily abandoned when it
was decided to bring that work to an immediate close. Fortunately, the
lake received careful attention at the hands of earlier expeditions and sur-
veys, and its history is already as well known as that of auy other inland
lake, with the possible exception of the Dead Sea and the Caspian.
surveys.-It wMs survcyod and mapped by Stansbury in the years 1849
and IS."")!). It was again map})ed by the Fortieth Parallel Survey in ISCS,
and the data for a third map have since been gathered by the Survey West
of the lOOtli Mendian. In connection with the first and second of these
surveys analyses were made of the brine, and the first and third ran nu-
merous lines of sounding. Additional data of value were gathered by Fre-
mont in 1843 and by various parties of the Wheeler, Ilayden, and Powell
surveys. As a member of the PoAvell Survey, the wnter made a study of
the recent oscillations of the lake; and a system of records by means of
gauges, instituted at that time, h;is ])een continued by the U. S. Geological
Survey.
Depth. Tluf most striking feature of the hydrography of the lake is its
shallowness. The soimdings taken by Stansl)ury indicate a mean deptli, in
18.0(), of nbout thirteen feet; and although the height of the wnter .surfnce
afterward rose fully ten feet, the rise was accompanied by the additimi of
such large ;ireas of slinllow water that the mean depth was increased less
than .''» feet. Tlie iiiaxiiiuiiii (lej)th reported by Stansbury is 3(5 feet, and at
the highest stage, 49 feet of water was found near tlie same place.
Gauging.-In 1875 the first definite determination of the lake level was
made, and since that time a nearly continuous record of its oscillations has
DEPTH OF GEEAT SALT LAKE. 231
been kejit. A less accurate knowledge of the change of level, Ijased in
part on tradition, extends back to 1845. In the following account of tlu;
oscillations, the direct observations will be first described, and afterward the
indirect determinations.
In the year 1875, Dr. John R. Park, of Salt Lake City, at the sugges-
tion of Prof. Joseph Henry of the Smithsonian Institution and with the co-
operation of other citizens, instituted a series of observations. There was
erected at the water's edge at Black Rock a granite Idock cut in the form of
an obelisk and engraved on one side with a scale of feet and inches; and
Mr. John T. Mitchell was engaged to observe the water-height at intervals
of a few days. In 1877 Mr. Jacob Miller of Farmington, at the instance
of the writer, erected near that place, in a slough connnunicating with the
lake, a post of wood graduated to inches. Upon this gauge a record was
begun in November, 1877. In the course of time the lake fell so low that
its water-level could not he. determined by either of these gauges, and in
1879 a third was set up by Mr. E. Garn at the bathing resort known as
Lake Shore. The Lake Shore gauge consisted of a wooden pile driven into
the clay bed of the lake and engraved with a scale of feet and inches. The
continued recession of the water rendering it apparent that this gauge also
would eventually become useless, the U. S. Geological Survey in 1881 es-
tablished a fourth gauge at Garfield Landing, a short distance west of Black
Rock. It consisted of a red-wood jdank, with a scale of feet engraved
and painted, spiked to a ]»ile of the steamboat wharf at thnt point. The
Survey also ascertained th relative height of the zeros of all the gauges;
and as none of them were of a permanent nature, it connected them by
leveling with a durable l)ench-mark set out of the reach of the waves of
the lake.
The Black Rock bench, as it will be convenient to call it, consists of a
granite post about three feet in length, sunk in the earth all )>ut a few inches,
on the northern slop<^ of a, small limestone knoll just south of the railroad
track at Black Rock. Its top is dressed square, al)out 10 by 10 inches, and
is marked with a -f . A sketch-map (PI. LI) was made of the locality in
1877, at the time of the establishment of the bench, and it is hoped that
this will serve for its identification at any future time.
232 LAKE BONNEVILLE.
Observations of lake level were made on tlie IJlack Rock gauge troiu Sep-
tember, 1875, to October, 1876, and single observations were made in July
and October, 1877. The P'armington gauge was used from November, 1877,
t(i November, 1879; the Lake Shore gauge fmiii November, 1879, to Sep-
tember, 1881 ; the Garfield Landing gauge from Api-il, iSSl, to June, iSSd.
The Garfield Landing gauge was inspected l)y mcml)ers of tlic corps
from time to time until 1884, when Salt Lake City ceased to ))e a base for
field operations. In 1886 Prof. Marcus E. Jones of that city ascertained
and reported that the gauge had suffered accidents wlierel>y its zero liad
been raised three tir four inches, but the dates of change were not learned.
In June of the same year it was destroyed by a storm. Prof. Jones then
began observations of the water height, and eventually prepared and in-
stalled a new gauge, placing it near the position of the old one at Garfield
Landing, and fixing its zero at the same height. This gauge, which will 1 le
called the New Garfield, is still in use.
All of the gauges except the New Garfield have by various accidents
become displaced, so that the authenticity and coherence of the i-ecords
depend wholly on the leveling and other observations conducted tt) deter-
mine the relative heights of the gauge zeros. Connection between the
Farmington and Lake Shore gauges was established by the writer by spirit-
level at the time of the institution of the latter gauge. The Lake Shore
and Garfield Landing gauges, which are separated by a space of more than
20 miles, were observed simultaneou.sly for a period of five days in March,
1881, the lake being at the time little disturbed by wind. In 1877 the late
Mr. Jesse W. Fox and the writer ran levels from the Black Rock "■iiuffe to
tlie Hlack Rock bench; and in 1881 Mr. Russell, by the aid of the .s])irit-
level and the level aff"orded by the calm lake surface, connected the Garfield
gauge in like manner with the Black Rock bench.
These various determinations, together with others, have been compiled
and reduced to a system by Mr. Wel)ster, Avhose report on the hypsometric
work performed in connection with the Boimeville investigation will be
found in Appendix A. He has selected the zero of the Lake Shore gauge
as the datum or reference point for all heights within the basin. I insert a
table of gauge heights based on liis compilation.
GAUGING GREAT SALT LAKE.
233
Tablk VII. Datum PoUtts coiincvttd with iht gaiiyitnj of Great Salt Lake,
lilack Rock Bencli
Kiirminston Beuch
lihick Itock Gau{:;e Zt^ro. .
Farniiugton Gauj;o Zero . ,
Lake Shore Gaiifje Zero .
Garticld Gauge Zero
New Garfield Gauge Zero
Feet.
+41.8
+ 1G. 7
+ 5.3
+ 3.K
0.0
- 4.0
- 4.6
Oscillations since i875.-Tlie followiug' ta])le sliows iill tlie trustwoi'tliy obsei'va-
tions recorded by the observers at these several stations. It does not cover
the entire i)eriod from 1875, but the breaks are unimjxirtant.
Table VIII. Record of Oscillations of Great Salt iMke.
Referred
Gauge.
Observer.
Year.
Day.
Keatling.
to Lake
Shore
Zero.
Ft. In.
Feet.
lilack Eock
J.T. Mitcliell...
1875
Sept. 14
0 0
5.8
22
0 5i
5.7
25
0 5
5.7
Oct. 0
0 4i
5.0
12
0 4
5.0
18
0 :ii
5.0
20
0 3
5.5
Xov. 9
0 2
5.4
10
0 n
5.4
23
0 4
5.6
29
0 .-.i
5.7
Dec. 7
0 5
5.7
14
0 51
5.7
21
0 6
6.8
1870
.Ian. 5
0 8
5.9
11
0 K*
0.0
29
0 9
6.0
Feb. 1
0 9
0.0
15
0 95
6.1
22
0 9i
6.1
Miir. 15
0 11
0.2
22
1 0
6.3
28
1 04
0.3
Apl. 17
1 2
6.4
25
1 3
6.5
May 2
1 4
6.6
22
1 9
7.0
J"une 2
1 11
7.2
8
2 0
7.3
13
2 2
7.4
-
23
2 4
7.6
234
LAKE BONNEVILLE.
Table VIII. Record of Oacillationa of Great Sail Zaic— Continued.
Ileforred
(r.anKo.
Observer.
Year.
Day.
Reading
to Lako
Shftre
Zero.
Fl. In.
Feet.
m.vk Kork
J.T. Mitchell .
1876
Juno 30
2 6
7.8
July 18
2 3
7.5
25
2 4
7.0
Auk. 1
2 3
7.5
10
2 2
7.4
22
1 9
7.0
20
1 8
0.9
30
1 8
B. 9
.Sept. 14
1 7
6.9
10
1 6i
0.8
2G
1 6
6.8
Oct. 0
1 51
6.7
G. K. Gilbert ..
1877
July 12
2 0
7.3
Oct. 19
0 10
6.1
Nov. 24
2 1
5.8
Farmington
.T Mlllor
1878
Jan. 21
2 li
2 2i
5.9
Mcli. 28
6.0
May
2 5
0.2
June .10
2 C
6.3
July 18
2 3J
6.1
Nov. 1
1 0
4.8
Doc. 11
0 11
4.7
1870
May 2
1 4
5.0
Lake ehoro
E. Gam
Nov. 19
Doc. 2
2 6
2 C
2.5
2.5
10
2 7J
2.B
31
2 9
2.7
1880
Jan. 14
2 9J
2.8
29
2 7J
2.6
Fob. 23
2 7J
2.6
Mar. 10
2 9i
2.8
30
2 10
2.8
Apr. 15
2 lO.i
2.9
28
2 Il.i
3.0
May 12
3 1
3. 1
2fi
3 3.5
3.3
Juno 10
3 4
3.3
28
3 4i
3.4
July 13
3 3«
3.3
30
3 1
3.1
Aug. U
2 11
2.9
29
2 8
2.7
Sept. 14
2 5
2.4
20
2 2
2. 2
Oct. 15
1 ll.i
2.0
29
1 lOJ
1.9
Nov. 12
1 9
1.7
29
1 8i
1.7
Doc. 11
1 8J
1.7
14
1 9
1.7
RISE AND FALL OF GREAT SALT LAKE.
235
Table VIII. Record of Oscillations of Oreat Salt Lake — Continued.
Referred
Gauge.
Observer.
Tear.
Day.
Reading.
to Lake
Shore
Zero.
Ft. In.
Feet.
Lake ^horo
E. Garn
1«80
. 1S81
27
Jan. U
1 10
I 10
1.8
1.8
28
2 2
2.2
Fob. 14
2 0
2.5
28
2 6i
2,5
Mar. 14
2 7J
2.0
Garfield Landing . . .
T. Douris
Apr. 1
7 3
2.6
16
7 4J
2.7
May 1
7 8
3.0
16
7 11
3.3
Juno 1
8 0
3.4
10
8 OJ
3.4
July 1
7 lOJ
3.2
16
7 10
3.2
23
7 9
3.1
Aug. 2
7 6
2.9
19
7 4
2.7
Sopt. 8
7 0
2.4
10
0 n
2.3
Oit. 2
0 9
2. 1
10
6 9
2.1
Nov. 2
0 8
2.0
10
6 8
2.0
Die. 1
0 8
2.0
15
6 !l
2.1
lKS-2
Jan. 2
6 0
2.1
'
16
0 10
2.2
Fob. 2
6 inj
2.2
10
6 11
2.3
M;ir 2
0 IIJ
2.3
21
7 OJ
2.4
A pi. 1
7 n
2.0
IB
7 ;i
2.0
May 2
7 5
2.8
16
7 0
2.9
June 2
7 OJ
2.9
10
7 0
2.9
July 2
7 4
2.7
17
7 24
2.0
Aug. 2
7 0
2.4
15
6 10
2 2
Sei>t. 2
0 5
1.8
10
6 3
1.0
Oot,. 2
6 IJ
1.5
l.'i
6 0
1. 4
IVc. l.--.
0 0
1 4
30
0 0
1.4
18K3
Jan. 15
6 0
1.4
1
30
0 0
1.4
236
LAKE BONNEVILLE.
Taiilk VIII. Record of Oscillationn of Great Salt Lake — Continued.
Koferroil
Gauge.
Obsi-rvi-r.
Tear.
Day.
Heading.
to Lak.
Sliun-
Zero.
Ft. In.
Feet.
(lai'tii^lil Landing ..
T. Oiiuris
IKHI
Feb. ir,
G 1
1.5
.-SO
0 H
1.5
Mar. 15
G 2
1.5
A pr. 2
G 4
1.7
Si-]it, :i
0 0
1.9
10
0 2
1.5
Oi:t. 3
5 8
1.0
IS
5 5
O.R
Nov. 1
5 3
O.G
15
5 0
0.4
Doe. 2
5 0
0.4
15
5 0
0.4
I8K4
Jan. 2
5 0
0.4
15
5 Oi
0.4
Feb. 2
8 OJ
0.4
15
5 IJ
0.5
Mar. 1
5 2J
0.6
15
5 6
0.9
Apr. 1
5 8
1.0
15
5 11
1.3
May 2
G 2
1.6
15
0 5
1.9
June 1
7 0
2.4
15
7 3
2.6
July 1
7 5J
2.8
15
7 5J
2.8
Aug. 2
7 2J
2.6
15
7 OJ
2.4
Sept. 1
7 0
2.4
15
7 0
2.4
Oct. 2
7 0
2.4
15
G 11
2.3
Nov. 1
6 11
2.3
15
6 10
2.2
Doc. 2
0 1(1
2.2
15
0 11
2.3
1885
Jan. 2
7 1
2.5
15
7 2*
2.6
Feb. 2
7 3i
2.7
IG
7 5
2.8
Mar. 2
7 6
2.9
16
7 8J
3.1
Apr. 3
7 10
3.2
10
7 U
3.3
May 2
8 1
3.5
15
8 3
3.0
June 1
8 G
3.9
IG
8 9
4.1
July 2
8 10
4.2
15
8 n
4.2
lilSE AND FALL OF GliEAT SALT LAKE.
Tablk VIII. Itecord of OscillaHoiis of Great Salt toAe— Continued.
237
Gauge.
Observer.
Year.
Day.
Reading
Referred
to Lake
Shore
Zero.
<larfielil Lauding
T. Duuri.s
1885
Aug. 2
15
Si-iit. 2
15
Oct. 2
15
Nov. 1
15
Die. 2
15
Ft. In.
8 8
8 7
8 3
8 0
8 0
7 llj
7 11
7 9
7 9
7 11
Feet.
4.0
4.0
3.0
3.4
3.1
3.3
3.3
3.1
3.1
3.3
IKfG
Jan. 2
15
Feb. 2
15
Mar. 2
15
Apr. 1
15
May 2
15
8 0
8 1
8 35
8 5
8 7
8 9
8 10
8 11
9 0*
a I
3.4
3.5
3.7
3.8
4.0
4 1
4.2
4.3
4.4
4.5
New Garfield ....
M. E. JoHOs
June 2
July 20
9 2.i
8 lOJ
4.6
4.2
Oct. 2
8 2
3.6
Nov. C
8 0
3.4
Dec. 28
8 2J
3.6
1887
Feb. 5
Mar. 5
19
Apr. 2
10
May 7
22
30
8 H
8 4
8 5J
6 n
8 6J
8 5i
8 Kj
8 8i
3.5
3.7
3.8
3.8
3.9
3.8
4.1
4.1
June 10
June 22
July 4
14
Aug, 0
.Scjil. 5
20
O.t. 4
25
Nov. 11
8 8i
8 7J
8 f.J
8 55
8 IJ
7 Si
7 41
7 3i
7 IJ
7 1
4.1
4.0
3.9
3.8
3.5
3.1
2.7
2.7
2.5
2.5
1888
Jati. I
10
Feb. 1
24
Mar. 3
23
Apr 6
7 1
7 2J
7 3
7 4
7 4
7 (ij
7 7
3.5
2.6
2.6
2.7
2.7
2.9
3.0
238
LAKE BONNE VI LLK.
Tablk VIII. Jiccurd of Oacillalioiu of Great Salt Lake — Coutiuiioci.
Rtf.rroil
Gauge.
ObsHiver.
Y.-ivi.
Day.
Ueailiii;;.
til I.akii
SImre
Zfle.
/•Vrf.
Ft. In.
New Gartield
M. E. Jonea
IMS
May 8
7 5
2.8
30
7 53
2.9
.lurni 22
7 34
2.7
July 3
7 U
2.5
23
.6 9
2.2
An;;. 1
0 8
2.1
16
0 G
1.9
Si.pt. 1
6 4
1.7
15
« u
l-.l
Oct. 1
5 11
1.3
Nov. 1
5 5
0.8
10
5 7
1.0
~-
Dec. 10
5 7
1.0
1889
Jan. 1
5 7
1.0
16
5 7
1.0
Feb. 1
5 8
1.1
15
5 9
1.2
Mar. 1
6 0
1.4
25
6 1
1.6
Apr. 15
5 9
1.2
May 1
5 n
1.3
20
5 9
1.2
June 1
5 8
1.1
25
5 5
0.8
July 12
4 11
0.3
Aug. 10
4 0
-0.1
30
4 IJ
-0.5
Sept. 23
3 7
—1.0
Oct. 12
3 71
-1.0
Dec. 14
3 8
—0.9
1890
Jan. 4
3 9
—0.8
An examination of tliese observations, or of the curve plotted frftm
tlieni, shows that the osciUations fall readily into two classes; the one peri-
odic, completing its cycle in 12 months; the other non-periodic. The curve
in Figure 32 shows the nature of the annual oscillation, being derived from
the records of eight complete, though not consecutive, years. Three periods
were used: October 1, 1875, to October 1, 187G; Jaiuiary 1, 18S0, to Jan-
uary 1, 1883; and November 1, 1883, to November 1, 18S7. Tlu' curve
has a single maximum, falling near the summer solstice, and a single iiiiui-
mum, foiling five months later. The maximum is more acute than the
minimum. The range is IG inches. The rise occupies seven months and
THE ANNUAL RISE AND FALL.
289
the fall only five, but the most rapid change is that portion of the rise oc-
cuiTiug in May.
JAN
nre
MAR
ARL
MAY
JUN
JUL
AUG
SEP
OCT
NOV
de:c
/
N
^
/
\
^
^
\
__^
-fee6
/ s
/■O
OS
Fill. 32— Annual Kise and Fall oftlio watur suil'ace of Great Salt Lake.
The cause of this annual variation is at once apparent. The chief
accessions of water to the lake are from the melting of snow on tlie mount-
ains, and this occurs in the spring, occasioning the rise of the water from
March to June. Water escapes from the lake only by evaporation, and
evaporation is most rapid in sunnner. Before the influx from melting snow
has ceased, it is antagonized by the rapidly increasing evaporation; and as
soon as it ceases, the surface is quickly lowered. In the autunm tlie rate of
evaporation gradually diminishes; in November it barely equals the tribute
of the spring-fed streams; and In winter it is overpowered by such aqueous
product of mountain storms as is not stored up in snow banks.
It cannot be doul)ted that the nature of the annual oscillation is modi-
fied by the diversion of water for irrigation, but an attempt to discover the
modification failed. As the irrigation area steadily increased during the
time covered by the gauge records, it was conceived that the influence of
irrigation might become apparent if curves were separately derived from
the earlier records and the later, but it was found that neither the curve
deduced from four years of record between 1875 and 1883 nor the curve
deduced from four years of record from 1883 to 1887 difl"ered materially
from the curve based on the whole eight years.
Observations prior to 1875— TuHiiug uow to tlie iudircct determination of oscil-
lations prior to 1875, we have a collection of circumstantial and traditionary
data which sufficiently indicate the general nature of the non-periodic oscil-
lations since the year 1845.
240 LAKE BONNEVILLE.
From 1847 to the present time the ishmds of the lake have been used
as herd grounds. Fremont and Carrington islands have l)een reached by
boat, and Antelope and Stansbury islands partly by boat, partly by fording,
and partly by land communication. A large share of the navigation has
been performed by citizens of Farmington, and the shore in that neiglibor-
hood is so flat that changes of water height have necessitated frequent
changes of landing place. The pursuits of the boatmen were so greatly
affected that all of the more important fluctuations were impressed upon
their memories; and most of the changes were so associated \vith features
of the to})ograpliy that some estimate of their quantitative values could be
made. The data which thus became available were collated for the late
Professor Henry by Mr. Jacob Miller, a resident of Farmington, who took
part in the navigation. His results agree very closely with those derived
from an independent investigation of my own, which has already been re-
corded in an essay on the Avater sup])ly of Great Salt Lake, constituting
Chapter IV of Powell's "Lands of the Arid Region." The following pai-a-
graplis are transcribed with little change from that volume.
Antelope Island is connected with the delta of the Jordan River by a
broad, flat sand bai- tliat has lieen usually submerged but occasionall\- ex-
posed. It slojjcs very gently towards the island, and jiist where it joins it,
is interrupted by a narrow channel a. few inches in depth. For a number
of years this bar afforded the means of access to the island, and many per-
sons traversed it. By combining the evidence of such persons, the condi-
tion of the ford has lieen ascertained up to the time of its final aliandon-
ment. From 1847 to 1850 the bar was dry during the low stage of each
winter, and in summer covered by not more than 20 inches of water. Tlien
began a rise, which continued until 1855 or 185fi. At that time a horseman
could with (lifHculty ford in winter, Itut all coininunicatioii was by boat in
sunnner. Then the water fell for a series of years, until in iSdO and ISdl
the bar was again dry in winter. The spring of ISll-J was iTiarked \)y an
unusual fall of rain and snow, wherebv the streaius were greatly Hooded
and the lake siu'face was raised several feet. In subsequent yeai-s tlie rise
continued, until in 1.SG5 the ford became impassable. According to Mr.
TKADITIONAL HISTOKY OF GKEAT 8ALT LAKE. 241
Hiller, tlie rise was somewhat rapid until 1868, from which date until the
establishment of the gauges, there occurred only minor fluctuations.
Since these paragraphs were written the publication of Fremont's
"Memoirs of My Life" has afforded a still earlier observation. On the liith
of August 1845 he rode across the shallows to Antelope Island, the water
nowhere reaching above the saddle girths.'
For the purpose of connecting the traditional history as derived from
the ford with the systematic record afterward inaugurated, I visited the bar
in company with Mr. Miller on the 19tli of October 1877, and made careful
soundings. The features of the ford had been minutely described, and there
was no uncertainty as to the identification of the locality. We found D feet
of water on the sand flat, and 9 feet 6 inches in the little channel at its eda-e.
The examination was completed at 11 a. m.; at 5 p. m. the water stood at
10 inches on the Black Rock gauge.
The Antelope Island bar thus affords a tolerably complete record from
1845 to 1865, but fails to give any later details. It hap2)ens, however, that
the hiatus is filled at another locality. Stansbury Island is joined to the
mainland by a similar bar, which was entirely above water at the time of
Capt. Stansbury's survey, and so conthiued for many years. In 1866, the
year following that in which the Antelope bar became unfordable, the water
for the first time covered the Stansbury bar, and its subsequent advance
and recession have so affected the pursuits of the citizens of Grantsville
wilt) used the island for a winter herd ground, that it will not be difficult
to obtain a fidl record by compiling their incidental observations. While
making the inipiiry I had no opportunity to visit that town, but elicited the
following facts by correspondence. Since the first flooding of the Ijar the
dej)th of water has never been less than a foot, and it lias never been so
great as to prevent fording in winter. But in the summers of 1872, 1873
and 1874, during the flood stage of the annual tide, there was no access
except by boat, and in those years the lake level attained its greatest lieight.
In the spi'ing of 1869 the depth was 4 J feet, and in the autumn of 1877, 2 J
feet.
'Vol. 1, p. 431.
MON I 16
242 LAKE BONNEVILLE.
The last item shows tliat the Stansbury bar is 7 feet higher than the
Antelope, and serves to connect the two series of observations.
Further inquiries may render the record more complete and exact, but
as it now stands all the general features of the fluctuations are indicated as
far back as 1845. Beyond that time there is no tradition, but there is a
single item of circumstantial evidence worthy of mention. All about the
lake shore there is a storai line marking the extreme advance of the water
during gales in the summers of 1872, 1873 and 1874. It is indicafed by
driftwood and other shore debris and is especially distingui.shed by the fact
that it marks a change in vegetation. In some places vegetation ceases at
this line, but usually there is a straggling growth of herbaceous plants able
to live on a saline soil. Above the line, on all the steeper slopes not sub-
jected to cultivation, the sage and other bushes flourish, but below the line
they are represented only by their dead stumps. The height of this storm
line above the contemporaneous still-water surface varies with the locality,
being much greater on a shelving coast, over which the water is forced to a
considerable distance by the winds, and especially small upon the islands.
On the east side of Antelope Island it was found by measurement to be
three feet above the summer stage of the lake in 1877, or about one foot
above the winter stage in 1873.
A lower storm line was observed by Stansbury in 18.50, and has been
described to me by a number of citizens of Utah who were acquainted with
it at that time and subsequently. The lake was then at its lowest observed
stage; and the storm line was so little above it that it was submerged soon
after the rise of the lake began. Like the line now visible, it was marked
by di-iftwood, and a growth of bushes, including the sage, extended down
to it; but below it no stumps were seen.
The relations in time and space of these two storm lines contribute a
page to the history of the lake. The fact that the belt of land between
them supported sage bushes shows that previous to its present submergence
it had been dry for many years. Lands washed by the brine of the lake
become saturated with salt to such an extent that even salt-loving plants
can not live upon them; and it is a familiar fact that the sage never grows
in Utah upon soil so saline as to be unfavorable for grain. The rains of
SECULAK OUEVE OF GEEAT SALT LAKE.
243
many years, and perhaps even of centuries, would be needed to cleanse
land abandoned by the lake so that it could sustain the salt-hating bushes;
and we cannot avoid the conclusion that the ancient storm line had been
for a long period the limit of the fluctuations of the lake surface.
1
1
^
7j
^
OS.
_
.'
\
^ . .__
/
-^^
''
/
^-^
■\
"■-----''
\
.-'-''
\
.inr
Fig. 33.— Xon-Pi rioilio Ri.so and Fall of Great Salt Lake.
A. I. 7!. = Aiitiloim Island Bar. S. I. B. i^Staiisbuiy Ishind Car. O. .S". = Old Storm line. JV. .S. = New Storm
line. The borizootal scale represtuta time. The vertical scale of feet is referred to the zero of the Lake Shore Gauge as a
datum.
The curve in Fig. 33 embodies the results of direct observation and of
traditional evidence as well as the inference from the phenomena of the
ancient shore-hne. It is th-awn as a full line where based upon definite
information, and as a broken line where the data are less precise. That to
the left of the ordinate representing 1845 is intended to express merely the
postulate that there were then, as afterward, oscillations, and the conclusion
that those oscillations did not exceed the level of the ancient storm-line.
The annual oscillation is omitted; the non-periodic only is represented.
The principal facts illustrated by this curve are, that during the historic
period in Utah the lake has twice risen and twice fallen, the second fall being
now in progress; that the second rise was carried five feet above a line which
had not been submerged for several decades; and that the total observed
range of fluctuation is about eleven feet.
Changes in arca.-Tlie inclination of the shores is in many directions so grad-
ual that this oscillation of eleven feet has been accompanied by very notable
changes in the extent of the water surface. Fortunately, the two maps of
the lake that have been published are based upon surveys made at such
times as to illustrate this change. Stansbury perfonned his field work in the
years 1849 and 1850, when the lake was at its lowest observed level, and
the topographers of the Fortieth Parallel Survey delineated the lake margin
in 1869, when the water was mthin a few inches of its highest stage. PI.
244 LAKE BONNEVILLE,
XXXIII is compiled from the two maps conjointly, so as to exhibit tlie
position and extent of the belt of land submerged by the rise of the lake.
Upon the Stansbur}' map the water surface has an area of 1750 miles; up(ni
the King, or Fortieth Parallel ma]), an area of 2170 miles, the increment
being 24 per cent, of the smaller area.
The ability of the lake to dilate rapidly the water surface exposed to
evaporation must ordinarily prevent any great fluctuation in its height.
The effect of each temporary increment or decrement to either water sup})ly
or rate of evaporation is by this means quickly obliterated, and cumulative
results are prevented. The lake level must be conceived to fluctuate nor-
mally within narrow limits, and the last high stage, in which the water was
not merely carried above the old storm line, but maintained at a greater
altitude for a period of eight or nine years, may be assumed to indicate
some powerful and unusual cause.
Causes ofchangc-Tlie fact tluit tlic exceptional lake maximum has occurred
during the occupation of the region by the white man suggests that it may
have been occasioned in some way by human agency; otherwise its cause
is natural, and is almost of necessity climatic. Let us first consider the pos-
sible climatic causes. The height of the lake is stationary only when the
gain from inflow and from rainfall on the water surface is precisely balanced
by the loss from evaporation. Whenever in any year the total access of
water exceeds the evaporation, the surface rises; when the evaporation ex-
ceeds, the surface falls. The elements of climate to be considered are there-
fore those which affect the water supply and the evai)oration. The rate of
evaporation is a function of the local temperature and humiditv of the air
and of the velocity of the wind. The water supply depends ])rimarilv on
the rainfall and secondarily on the I'ate of evaporation, since a jxHtion of
the water falling on the land is evaporated, and it is only the unevaporated
part which finds its Avay to the lake. Other things being ecjual, the lake
surface should rise during those years in which the precipitation in rain and
snow is great, the temperature low, the relative humidity liigh, or the wind
velocity small.
Our climatic record in the Cordilleras is imperfect, but such as it is, it
extends back nearly as far as the record of lake oscillation. The account
U S. GEOLOGICAL SUPA'-S-:
LAKE B0NNE'.1LLE PL- XXXHI
I i 11 1 r ±
Julius BiCTi & Co Lith
COMPARATI\'E MAP OF
GREAT SALT LAKE , UTAH
COMPILKn TO SHOW
ITS INCREASE OF AREA.
ThtTopoqraphy and lattr sfiorc-line fwe taken from the Sui-veyot'(2arfn^efang,
U.a. Geologist; the earlier shorerUne. from the Survey of(hptMow(wd StansburyUSA.
WHY DOES THE LAKE RISE AND FALL? 245
it affords of the wind velocity and tlie relative humidity is not sufficiently
definite to be of value in this connection; but the records of rainfall and
temperature may profitably be compared. For this ])ui-pose I have availed
myself of the statistics gathered by the Smithsonian Institution and discussed
by Mr. Charles A. Schott in his papers on the precipitation and atmos])heric
temperature of the United States, and those gathered and published by the
U. S. Signal Corps.
Aqueous precipitation is so capricious in its distril)ution that the record
kept at a single station affords no valuable indication of secular changes.
It is only by the combination of a system of observations made at a gi'oup
of stations, that any trustworthy indication can ])e obtained. For the present
purpose the stations of the Great Basin and of the adjacent portions of the
Pacific Coast have been used, choice being restricted t<i those at which
records have been kept for terms of years. These are: Astoria and Port-
land, Oregon; Fort Point, Sacramento, San Fi-ancisco and San Diego, Cal-
ifornia; Boise City and Fort Boisti, Idaho; Salt Lake City and Camp
Douglas, Utah. In the reduction of the observations the precipitation for
each year and station has been divided by the mean annual precipitation
for that station, and the several quotients have been arranged under their
appropriate years. The mean of all the quotients for each year has then
been found, and these means have been assumed to express the relative
precipitation for the several years in the indicated districts. The curve
representing these means is reproduced in No. 1 of PI. XXXIV.
A brief consideration will show that this curve is not directly compara-
ble with the curve of lake oscillation, III. Assuming for the moment that
the oscillations of the lake are determined purely by variations of precipita-
tion, then each year of excessive precipitation should correspond to a rise
of the lake, and each year of small precipitation to a fall. A maximum of
lake level would occin- at the end of a series of years of great rainfall, but
would not, except by accident, correspond in time with a year of maximum
rainfall. If the area of the lake and the rate of evaporation were constant,
the height of the lake level at any time could be determined by the summa-
tion of all the precedent precipitation factors up to that time ; liut the fact
that the lake expands as it rises causes the annual loss by evaporation to be
246 LAKE BONNEVILLE.
a function of the lake's lieight. Tlie exceptionally great rainfall of an indi-
vidual year, by increasing the area of the lake, initiates an excess of evapo-
ration which eventually eliminates its influence from the curve of lake
oscillation; the exceptionally small rainfall of an individual year, by dimin-
ishing the area of the lake, initiates a defect of evaporation which likewise
eventually eliminates its influence from the curve of lake oscillation. The
height of the lake at any time, as dependent on precipitation, is therefore to
be derived by such an integration of the precipitation of antecedent years
as will give the greatest weight to the years just passed and a progressively
smaller weight to those more remote. An integration of this sort has been
made, and is expressed in the curve marked II. It was arbitrarily assumed
that the influence upon the lake level of the precipitation of a given year
diminished in arithmetic ratio so as to disappear in ten years, and the inte-
gration was based on this assumption. For example, the factor for 1870
was multiplied by ten, that for 18G9 by nine, that for 18G8 by eight, etc.,
the factor for 18G1 being the last included and being multiplied by unity.
The sum of these several products was divided by the sum of the multipliers,
55, and the quotient was assumed to represent the integrated precipitation
factor at the end of the year 1870.
The temperature was treated in a sunilar manner. Prior to the insti-
tution of the meteorologic observations of the Signal Corps, temperature
was observed at a number of military posts and a few cities, and the records
have been compiled and discussed by Mr. Schott. These observations have
doubtless been continued at most points up to the present time, but they
are less accessible than those of the Signal Service, and the latter have been
employed for the period from 1872 to 1883. The Signal Service stations
in the region already indicated include Portland, Ore., and San Francisco,
and San Diego, Cal., occupied for the entire period; and Umatilla, Ore.,
Visalia, Cal., Boise City, Idaho, Salt Lake City, Utah, Pioche, Nev., and
Prescott, Ariz., occupied for terms varying from five to eight years. For
each of these stations the mean of the annual means of temperature was
subtracted from each of the annual means, and the residuals were arranged
in columns according to years. The mean of the residuals for each year
was then deduced, and the successive mean residuals were plotted in a curve.
U S. GEOLOGICAL SURVEY
LAKE BONNEVILLE PL. XXXIV
50
'60
'70
'80
II II
II III -.-..- ....
1 4
K
IT
12 JL ^5
t
ft ^ Ljrr^
t A -/5 1
'' H^^^ 4 ^ -i
15:5, Ai^v ^^ /_ V
M y \- ^i i-A4
^V ^ ^^ ^^.
« ^ t^^ y i
2lt V ^ \
v--^ W TJ
6
J^^^
7 Y
A A^^y^^
t ^^^r^-. >^ n
^^ ^^ -JU
-^ V A S^^
■^I^ A /X
4 Ay'^ V
Kt V- ^-5
I ^^ A
At ^ 7 ^
'-t- K A4^ ^
X3I
^'»».^'^""*^\^
+ 6 ft
/ ^/^N
> S
+ 4
/ \ Itt
/ >
+ 2 2
^^.
^^1 ^
^.
0 / ^\, /
/ \ /
- 2 ^ 3 ^
■^ S^ ^
y^r-A.
_j ^^ "^
-.^ X i^
^ t
z ^==^
T
y^' \
V
r-" "^^
>,
-u-"^
\
^^^
i +
-—^ \,'
+ 2- \
-t-r ^v S
I^ A
\^ UA
t^ ^V^ ^^ ^
0 it V V^
• \ M rf \
\ h
A i ^ /
-1° V^^ S-^
^ \4 ^ C V
^^ \r ^
-t-tt ^
- Z'
T ^
1
L.l 1 III
Julius Bien * Lo.hdi
CLIMATE CURVES
LAKE CURVES AND CLIMATE CURVES. 247
This curve was found to be almost identical with that derived from the San
Francisco observations alone and to be closely simulated by the curves of
the other individual stations. It was therefore deemed legitimate to employ
the San Francisco curve as representative of the district for the period
antecedent to the institution of the Signal Service observations.
The San Francisco observations, however, were not employed alone.
Mr. Schott has combined with them data from Alcatraz Island, Angel Island,
Fort Point and Presidio, all of which stations were in the immediate vicinity.
His results are published in the form of mean annual temperatures, and
these have been prepared for the present purpose by subtracting from each
the mean of the series. The residuals thus obtained and the residuals de-
rived from the Signal Service observations are plotted in curve V of PI.
XXXIV. This curve may be considered to represent, with a fair degree
of approximation, the non-periodic oscillations of temperature within the
indicated period in the district of the Great Basin and Pacific Coast.
Here, too, it is evident that a direct comparison with the curve of lake
oscillation should not be made; whatever the influence of temperature upon
the volume of the lake, whether through rainfall or evaporation, it would
be semi-cumulative. The temperature determinations have therefore been
submitted to the same process of special integration as the precipitation
determinations; it was again assumed that the influence of each year's
temperatin-e would diminish in arithmetic ratio so as to disappear in ten
years. The deduced curve, IV, is far more regular than that derived from
precipitation, and presumably represents the slow secular oscillation.
In comparing the integrated temperature curve with the curve of lake
oscillation the question arises whether the maxima of the former should be
compared with the maxima or the minima of the latter. If temperature
affects the lake chiefly through rate of evaporation, the maxima of one curve
should coincide with the minima of the other. If its chief influence is ex-
erted through precipitation, the correspondence should probably be found
in the same way; but about this there is diftereuce of opinion. Fortunately,
it is unnecessary to discuss the subject in this connection, for whether the
comparison be made directly or by inversion, it is equally evident that the
curves are inharmonious.
248 LAKE BONNEVILLE.
Tlie integrated precipitation, curve IT, resembles the curve of oscilla-
tion in several })articulars. Its maxinmm from 1852 to 1855 is comparable
with the lake maximmn in 1855 and is^fi. Its minimnm from 1858 to 18G0
is comparable with the lake mininmm in 1860 and 1861; and dui-ing the
great maxinunn of the lake from 1867 to 187!) the precipitation curve is
for the ]nost part above its mean line. The only great disparity occurs in
the years 1S(;8 to 1865, when the precipitation curve shows a minimum
unrepresented in the curve of lake oscillation. The precipitation curve is
therefore on the whole similar, and indeed its correspondence is quite as
close as could be expected by one who realizes how imperfectly the average
precipitation of a region is rejjresented by the observed precipitation at
a small number of stations. There is, therefore, some su])port for the
hypothesis entertained by many ])ersous that the exceptional rise of Great
Salt Lake which culminated in 1873 was due to au increase of precip-
itation.^
Turning noAv to the consideration of the influences exerted upon the
lake by man, we find them separable into two classes; first, those which cause
a greater proportion of the precipitation falling on the Innd to be gathered
by the streams and carried to the lake; second, those which cause a smaller
pro]iortion of the precipitation to reach the lake. The supposed influence
of deforesting on the rainfall itself need not be discussed, because in this
region no considerable body of forest has been destroyed.
The chief influence of man in increasinfj the inflow of the lake is through
the grazing industry. In their virgin condition many of the lowland vallej-s
and all the upland or mountain valleys were covered by grass and other
herbaceous vegetation. These have been eaten off" Ijy the herds of the white
man, and in their place has sprung up a sparse gi'owth of low bushes between
which the ground is bare. From this bare svirface it is believed that the
water falling as rain or freed by the melting of snow, runs off more readily
than from the original grassy surface, so that a smaller share of it is evap-
orated in situ and a larger share flows through the water courses to the
lake. This change has affected a large total area; and if its influence ujjon
' The observational data discussed close with the year 1883. As the niauusoript goes to press
they are available to 1889. The later data have not been systematically treated, but their inspection
shows that the general conclusion is sustained by them.
MAN'S INFLUENCE ON GREAT SALT LAKE. 249
water supply is here coiTOctly interpretecl, it is a factor of importance.
Another tactor of tlie same tendency is the draining- of marshes and beaver
ponds. IMany of the small streams of the basin were clogged by beaver
dams, and the courses of some of these have been opened by the white man
for the purpose of increasino- the supply of water for irrigation. The in-
creased su])ply has been utilized for irrigation during a portion only of the
year, and at other times has joined the streams flowing to the lake.
Plowing and irrigation have the contrary effect. Land broken up for
cultivation is tliei-eby rendered more porous, so as to retain a larger portion
of the rain falling upon it. I'liis i-etained portion is chiefly returned to the
atmosphere by evaporation and is tluis lost to the lake. The effect of irriga-
tion is precisely similar. The water diverted from the streams and spread
out on the land for the })urpose oH nourishing crops is restored to the atmos-
l)here by evaporation from the surface of the soil and from the leaves of
plants. In 1877 the writer estimated that the inflow of Great Salt Lake
was diminished six per cent by this cause.
With the exception of iri-igation, it is impossible to give quantitative
expression to these factors. Those which tend to increase the lake })robably
culminated fifteen or twenty years ago, and have .since remained constant.
Those which tend to diminish the lake have increased continuously for the
last 35 years. The time is probably past when the net tendency toward
lake increment was at a maximum, but it is not entirely clear whether the
present sum of human agencies tends toward lake expansion or lake con-
traction. Li any case the consideration of the qualitative relation of the
several factors suffices to sliow that a curve representative of the influence
of hinnan agencies could have but a single maximum, and could not corre-
spond in detail with the determined curve of oscillation.
Ten years ago I discussed at some length the comparative merits of
the climatic theory and the theory of human agencies,' concluding that
neither was inconsistent with the facts and that the truth might include
both. I pointed out that the former appealed to a cause that may be ade-
quate but is not independently known to exist, while the latter appealed to
causes known to exist but quantitatively undetei'mined. Since that time
' Lands of the Arid Region, pp. 68-77.
250 LAKE BONNEVILLE.
the publication of the second edition of Mr. Schott's discussion of i-ainfall
and the progress of the work of the U. S. Signal Corps have rendered it
j^ossible to construct the most iinportant fom])arative climatic curves, and
the subject is here resumed for the purpose of exhibiting the relation of
these curves to the curve of oscillation. The coiTcsjiondence of the inte-
grated precipitation curve to the curve of lake oscillation is siifficientlv close
to indicate a causal relation, especially in view of the fact that rainfall is the
climatic factor to which hypothesis most naturally appeals.
In the present as])ect f)f the problem, precipitation seems entitled to
rank as the dominant factor, the results of its variation being only slightly
modified by the variations of temperature and the changes introduced by
gi-azing and agriculture.
Future changes.-Thosc humau ageucles which tend to increase the water
supplv of the lake, namely, grazing and draining, have acquired a status
that is practically permanent, but those which tend to diminish the supplv,
namely, plowing and irrigation, have not yet ceased to increase. In 1877,
when the consumption of water by irrigation w.as estimated at six per cent, of
the inflow of the lake, the intervention of the irrigator was restricted to the
minor streams of the basin. The main bodies of the Bear and of the Jordan,
the largest of all the streams, flowed unimpeded to the lake. Since that
time, the diversion of the water of the Jordan has been undertaken on a
large scale ; and the time can not be distant when its entire volume will be
utilized. The Bear River presents greater engineering difficulties, and has
not yet been brought under control; but sooner or later a large district will
be redeemed by means of its water, and the lake will be correspondingly
deprived of tribute. Human agency is thus destined to play an iniportant
part in the detemaination of the future history of the lake. The next ten
years will witness its shrinkage, for lack of affluent water, to a size smaller
than has before been observed. It is not to be expected that it will ever
share the fate of Sevier Lake, because the conservation of all the stream
water for irrigation is not economically practicable, but it will })i"obably be
so reduced in voliune as to precipitate a portion of its salt.
The final system of irrigation will include the storage in artificial
reservoirs of the flood water of all the minor streams, and will cause the lake
FUTURE SHRINKING PROPHESIED. 251
to be deprived of all inflow except from saline creeks and from the unused
share of Bear River, l)ut this system is not likely to be established by the
present generation. The expansion of the methods now in vogue to a limit
dependent on the extent of tlie readily available arable land, together with
the construction of reservoirs on the most available sites, will employ about
two-thirds of the water supplv, and will proportionately reduce the area of
the lake.
One effect of si;ch a contraction of the lake will be to simplifv its out-
line. Antelope, Stansbury, Carrington, Hat, and Dolphin islands will he
permanently united to the land. Bear River Bay will be drained nearly to
the southern extremity of Promontory, and the bay east of Antelope Island
will be drained nearly to the northern end of that island. The Jordan, the
Weber, and the Bear will iniite their deltas in the vicinity of Fremont
Island, and will eventually fill up all of the sound east of that island,
reducing the lake to a linear body lying east of Stansbury Island and the
Promontory. With a lowering of the lake siu-face the projection of deltas
^will be a rapid process. During the recent high stage of the lake the chan-
nels of the three principal rivers have been converted, in their lower por-
tions, into estuaries whose sluggish current has permitted the accumulation
of silt. The volume of this silt has been at the same time increased by the
culti^'ation of the soil, an industry which always augments the detrital loads
of the streams. The lowering of base-level incident to the falling of. the
lake surface will cause the streams to erode this detritus and transport it to
the shore of the lake.
Saline Contents-Auother cffcct will bc the concentration of the brine. The
lake is so shallow that its volume is greatly affected by small changes of
level, and since the total amount of contained salts undergoes no appre-
ciable change, the strength of the solution is affected. Variations of salinity
have been observed by persons engaged in the manufacture of salt from the
brine, and quantitative expression lias been given to the same facts by the
analyses made from samples gathered at different dates. With the lake at
its lowest observed stage, 1850, Stansbury collected a sample of the brine
containing 22.4 per cent, of solid matter. From a sample gathered in 1873,
when the lake was at its highest stage, Bassett obtained 13.7 per cent, of
252 LAKE BONNEVILLE.
solid matter. At an intemiediate stage King- collected in 1869 a sample
containing 14.8 per cent, and Talmage in 1885 and 1889 obtained samples
yielding 1(1.7 and lit.G per cent. It would appear from a comparison of the
extreme results that with a rise of the lake surface of 10^ feet the salinity
was decreased by 39 per cent, of its amount; and, assuming that the quan-
tity of saline matter in solution remained unchanged, the volume of water
in the lake was at the same time increased 73 per cent.
While these results are approximately true, they should not pass with-
out (pialification. Careful comparisons of the several determinations of
salinity ^\\t\\ tlie several determinations of density and with the correspond-
ing determinations of height of water surface, reveal numerous discrepancies.
The comparison of salinities with densities shows that there are errors in
determinations of salinities or densities. Discrepancies between determined
salinities or densities on the one hand, and heights of water surface on the
other, suggest several sources of error. No collector of water samples has
placed on record the spot where the collection was made; one may have
stopped near the mouth of a stream and obtained too low a salinity; another
may have visited a lagoon of the shore with abnormally high salinity.
Stansbury and King neglected to record the dates of sampling; and of
the five samples analyzed three were collected before the establishment of
gauges; there is thus some uncertainty in determinations of the height of
the lake when its brine was sampled.
The accompanying analyses embody all our knowledge of the nature
of the brine and they accord so poorly with one another that they wai-rant
our speaking with confidence oidy of the most striking characteristics. The
principal base is sodium, and this exists chiefly in the form of chloride, but
also as sulphate ; next in rank is potassium, and then follow magnesium and
calcium. Despite the fact that calcium carbonate is precipitated on the shore
in the form of an oolitic sand, none of the analysts have succeeded in iinding
it in the brine; and it is probable that the weighable calcium found in two
of the samples exists in the form of sulphate. The theoretic combination
of acids and bases given in the lower division of the table is in the main
tentative only; but the readiness with which sodium sulphate is ol)tained
from the brine Avarrants the belief that it is one of the actual constituents.
THE SALT LAKE BRINE.
253
Wlien in winter the temperature of the water falls below 20° F., the precipi-
tation of this salt begins, and it sometimes accumulates in such quantity as
to be readily gathered from the bottom, or is even thrown upon the shore
by the waves.
The sodium chloride has become the basis of a large industry, being
manufactured for table and dairj- use as well as for metallurgic purposes.
This industry has so expanded since the close of my work in Utah that a
statement of its condition at that time Avould have historical value only. It
is re})orted that the output in 1886 was 23,000 tons; in 1887, 40,000 tons; in
1888, 21,000 tons. For several years sodium sulpliate cast on the shore Ijy
the waves in winter has been gathered, and its utilization for the production
of various sodium salts of commercial importance is already undertaken.^
The quantity of sodium chloride contained in the lake is about 400 millions
tons; of sodium sulphate, 30 millions tons.
Table IX. Anahjses of Wate>- of Great Salt Lake.
I. Sample taken id 1850; analysis by L. D. Gale.
II. Suniple taken in summer of 1869; analysis by O. D. Allen.
III. Sample taken in Auj;u8t. 1873; analysis by H. liassett.
IV. Sample taken in December, t885; analysis by J. E. Talmage.
V. Sample taken in August, 1889 ; analysis by J. E. Talmage.
I.
II.
III.
IV.
V.
Total aolids in 1000 parts of water. . .
224.2
1.170
148.2
[1.111]
136.7
1,102
167.2
1.122
195.5
1.157
First arrangement ofreaults; by acids and bases.
Parts
in 1000 of water.
Per cent, of total sulids.
I.
11.
III.
lY.
V.
I.
II.
III.
IV.
V.
124.5
12.4
85.3
84.0
9.9
49.6
2.4
.2
3.8
Trace
Trace
73.6
8.8
38.3
9.9
.6
3.0
90.7
13 1
58.2
1.9
.4
2.9
110.5
11.7
6.5.3
2.1
.8
5.1
55.8
6.0
38.3
.3
50.0
6.6
33.1
1.0
.2
2.5
51.9
6.6
28.6
7.4
.4
2.2
54.3
7.8
34.8
1.1
.3
1.7
56.5
6.0
33.4
1.1
• 4
2.6
Sulphuric acid (SO4) . . .
Trace
.6
Total
222.8
149.9
134.2
167.2
195.5
100.0
100.0
100.0
100.0
100.0
'The waters of Great Salt Lake. By James E. Talmage. Scieuoe, vol. 14, 1889, pp. 444-446.
254
LAKE BONNEVILLE.
Second arrangement of results ; hy theoretic cnmhinatiotis of acids and bases.
Parts in 1000 of water.
Per cent, of total solids.
I.
II.
III.
IV.
V.
I.
II.
III.
IV.
V.
Sodium chloride
202.0
118.6
88.5
18.9
11.9
10.9
2.0
2.0
135.9
l.'.7.4
90.7
79.1
65.9
14.1
8.9
8.1
1.5
1.5
B1.3
80.5
Mafjuoaiuin chloride ...
Sodium sulphate
2.5
18.3
14.9
9.3
5.3
.9
.9
11..1.
14.2
4.3
1.5
20.1
10.5
4.7
2.8
1.1
8.2
9.9
6.2
3.6
.6
.6
6.7
8.5
2.6
.9
10.3
5.4
2.4
1.4
Chlorine (excea.s)
222.8
149. 9
134.2
167.2
195. S
100.0
100.0
100.0
100.0
lOO.O
Xote. The first sample of water was collected by Stansbary, and its analysis is reported on p. 419 of the "Expedition
to the Gre.it Salt Lake." The second was collected by the Fortieth PariUel Survey, .nnd is rt-poi ted in Systematic Gtolojjy,
vol. I, p. .'">02, and Descriptive Geology, vol 2, p. 433. The third was collected by Dr. W. Marcet in August, l>^73, and is
reported in the Chemical News for Nov. 7th, 1873 (vol. 28, p. 2:tG) by n. Cassett. The fourth and fifth were collected by
J. E. I'almage in December, 1885, and August, 1889, and :ire rei)ortcd in Science, vol. H, 1889, p. 445. Gale reported the
salt.s as hero given in the first column of the second table. Allen's repoit includes two forais, the salts being given in
one and the alkalis and acids in the other. Allen's figures, a.s printed, aro not perfectly consistent: the report of the
combined salts baa been used in deriving the figures here published. Basaett's report was published in the form here given
in the third column of the first taltle. The entire error of analysis is computed iu chlorine in the second table, columns
II and III. Talma, e'a reaulta were published in the form given in the first part of the second table. Gale's and Tal-
mage's errors of analysis do not appear..
Sources of Saline Matter.-Tlie sources of tliG saliiie material may be considered
in two classes; the first including the rivers, the second the littoral springs.
The Bear, the Welder, the Jordan and a small number of creeks rise in up-
lands above the horizon of the Bonneville shore and bring to the lake water
Avhich is sensibly fresh, containing only minute quantities of mineral matter.
A cordon of springs about the shore of the lake rise through the Bonneville
beds, and are so far charged with salts leached from the sediments as to be
perceptibly brackish. With these should be classed also the Malade River,
the upjjer course of which is fresh, while the lower is rendered brackish by
the accession of saline water from thermal springs rising in the lied of the
stream' Avithin the Bonneville area. With only our 2)resent knowledge it is
iinjjossilile to say whether the fresh rivers or the In-ackish springs furnish
the greater saline tribute to the lake. The rivers only have been subjected
to chemical examination.
The constitution of the Jordan water was determined from a sample
collected in Utah Lake, the source of tlie river, and this determination is
taken to represent about one-third of the inflow of the lake. Bear Kiver
was sampled at Evanston, where the stream lias proliably two-thirds of its
ACCUMULATION PERIOD.
255
maximum volume Since this river furnishes alxnit luilf the water supply
of the lake, the sample is taken to represent one-third of that suppl)-. The
two analyses exhibit the constitution of two-thirds of the fresh-water tribute
of the lake, and it will l)e assumed that their mean shows the character of
the entire fresh-water tribute. In the following- table this mean is compared
with the analysis of the lake water as reported by Allen:
Table X. Accumulation Periods for Suhslnncen contained in the hrine of
Great Salt Lake.
Sabatance.
Parts in 1000.
V.
Accumu-
lation
Period.
I.
Bear River
Water.
II.
Utah Lake
Water.
III.
Meau of
I and II.
IV.
Great Salt
Lake Water.
Cblorine
.0040
. 0105
.0082
. 01'J4
.1306
.0178
Trace
.0558
.0186
.0086
. 0703
.0130
Trace
.0405
.0155
84. 00
9.87
49.05
2.40
.25
3.77
Trace
Trace
Tears.
34, 200
490
13, 400
18
850
Su'pbniic acid ..
Sodium
Calcium
Magnesium
.0432
.0125
Phoapbonis
Rate and Period of Salt Accumulation.-At the tlmC wllCU Allcu's Sample of briuC
was collected the lake had a mean depth of about 19 feet. The annual
inflow to the lake has been appi'oximately estimated as sufficient to add 5^
feet to its depth.^
The lake volume is therefore equaled by the inflow in three and a half
years, and in that period the saline strength of the lake is increased by an
amount equal to the saline strength of the inflow. Disregarding for the
present the supply from littoral springs, and considering only the supply
from rivers, we may, by the aid of these considerations, deduce from the
table tlie time necessary to store up in the lake the observed amount of
each of its mineral constituents. The results of such comj)utation appear
in the right-hand column of the table.
One of the most conspicuous features of these results is their variety.
The streams carry enough calcium to charge the lake to the observed extent
in eighteen years, but 34,000 years are necessary to similarly charge it
' Lands of the Arid Region, p. 72.
256 LAKE BONNEVILLE.
witli chlorine. Tlie explanation lies in the relative supply of these sub-
stuuccs and tlieir relative solubility. In the mountains from -vvhich the
rivers flo\v, calcium is afforded in luilimited quantity, while the su})ply of
chlorine is relatively very small. Chlorine, on the other hand, e-xisting as
it does in combination with sodium, is highly solulilc; while calcium, exist-
ing for the most part hi combination with carbonic acid, is sparingly soluble.
Chlorine therefore accumulates in the lake, while calcium is precipitated.
It is a matter of observation that calcium carbonate gathers on the shore
of the lake as oolitic sand, and it is probable that it also falls to the bottom
as a marly constituent of the lacustrine sediment. Calcium has therefore
reached its limit and is an unvarying constituent of the brine. The annual
accession is balanced by the annual precipitation.
The same remark applies to the magnesium. It is presumably precipi-
tated with the calcium, just as it was from the waters of Lake Bonneville,
and chemical analysis shows that a small portion of it is accumulated in
the oolite of the shore.
The short period necessary to accumulate the lake's store of sulphuric
acid, 490 years, indicates that it, too, has passed the saturation limit and is
being precipitated. It appears to exist in the lake in the form of sodium
sulphate, and it is probabl}' precipitated in that combination. The fact that
sodium sulphate is discharged from the lake by the extreme cold of winter
indicates that it must exist at ordinary temperatures in quantitities not far
from the saturation limit; and it is found to be the first mineral to separate
from the brine when evaporated by insolation.
There remain two substances whose long accumulation periods permit
us to doubt whether they have reach('(l tlie stage in whicli accession and loss
are equal. Sodium and chlorine, in their combination as sodium chloride,
constitute the most al)undant mineral, and no analysis has indicated that
the brine is fully saturated therewith. If it be true, as surmised, that the
annual supply of sul})huric acid is discharged from the lake by the precipi-
tation of sodium sulphate, the accumulation period for sodium chloride is
not properly represented by the period conq)uted for sodium. It is more
likely to be represented by the period estimated for the chlorine, namely,
34,200 years.
now OLD IS GREAT SALT LAKE? 257
If iio\y we recall to attention tlie tribute of the littoral springs, tem-
porarily ignored, it is at once apparent that onr table nnderestiniates the
annual tribute of sodium chloride and corres])ondingly overestimates its
accumulation period. We have no present means of determining the extent
of this ovei'estimate, but Ave can safely say that the period necessary to
charge the lake with common salt by means of the present sources and rate
of supply is not more than 25,000 years. Shall we conclude that 25,000
years ago the lake was fresh? or is there reason to believe that sodium
chloride, like the other constituents, is being precipitated by the lake as
rapidly as received? To this question a satisfactory answer can not be given,
but there are several considerations favoring the second alternative. First,
the circumstances coimected with the old storm line, to which reference has
already been made, indicate that the lake was smaller and therefore more
concentrated, for at least a few decades preceding the settlement of the
country, than it has been since. It may Avell be that a portion of the salt
was thrown down during this preliistoric period, and that it was condjined
with mechanical sediment in sucli way as to be preserved from resolu-
tion. Second, it is known that under special circumstances salt is now
precipitated at some points on the margin of the lake. Where a broad
expanse of water near the shore is exceedingly shallow, the local evapora-
tion is not compensated by the circulation, and the resulting- high concen-
tration leads to a discharge of salt. In passing from Grantsville to Stansbury
Island in 1881, Mr. Russell rode for a mile across a deposit of this character
an inch in thickness. Such a deposit as this would vmdoubtedly be redis-
solved if the lake rose, or if it fell so as to permit the action of rain; but
the fact of its formation indicates how triAdal are the conditions which may
determine precipitation. On the whole, it is not unreasonable to suppose
that each of the minima which occur in the ordinary history of the oscilla-
tions of the lake marks an epoch of precipitation, when a portion of the
saline matter is discharged .and a smaller portion is so combined with
other sediments as to remain a permanent deposit. While it can not be
true that the annual precipitation counterbalances the annual supply, it
is quite conceivable that a century's precipitation disposes of a century's
supply.
MON I 17
258 LAKE BONNEVILLE.
There seems thus a possibility, if not indeed a j)r()l)ability, that none
of the substances which have been ([uantitatively determined in the; Ijrine
and in the tributary rivers are undergoing accunudation in th(! lake; ])ut it
does not foUow tliat this equation of supply and discharge h;is sid)siste(l for
a long period. There are certain soluble l)ut very rare substances, such as
the comjiounds of Ijoron, lithium, iodine and bi-omine, which tend to accu-
mulate in inland lakes of great antiquity and have come to be regarded as
the diagnostic characters of age. Only one of these has been detected in
the water of Great Salt Lake, and that one is not found in measurable
quantity. The conclusion that the brine is recently accumulated accords
with the facts derived from the Bonneville history, for at the time of the
outflow the salts stored in the lake must have been discharged beyond the
limits of the basin. The age of the Gi'eat Salt Lake brine can not then be
greater than the antiquity of the second Bonneville flood.
We might conclude that the age of the brine is precisely equal to the
antiquity of the Bonneville flood were it not for the possibility that the lake
has since then been freshened by desiccation. Russell finds excellent reason
to believe that in the Lahontan basin, which is in many respects a duplicate
of the Bonneville, the flood epoch has been followed by one of very low
ebb, in which the residuaiy lakes have so dried away that all their saline
matter lias become entangled with mechanical sediment.^ A more recent
accession of water has produced a number of slightly brackish lakes, whose
feeble brines contain in their constituents no hint of great age. If the
Salt Lake basin has passed through a similar recent epoch of desiccation, it
is not easy to see how we should become cognizant of it. Provided the
antiquity of the epoch was sufficient to permit the subsequent accunudation
of the sodium chloride, the character of the brine would be sub.stantially as
we find it. For the present, at least, we must regard it as an open ques-
tion whether the existing lake with its characteristic brine dates from the
cessation of Bonneville overflow or from a subsequent epoch of extreme
aridity.
Fauna.-The animal life of the lake has been described by Packard,
who finds it to consist ot two species only, a brine shrinq), Artvmia yraciHs-
' Geol, Hist, of Lake Lahoutau, ]ip. 2'H-i'iO.
THE BKINE SHKIMP, 259
Verrill/ and the larva of a fly, Epln/did (/racilis Packard. Tlieso are very
abundant in certain seasons of the year. They feed upon alga', of which
three species have been recognized. The meagerness of tliis fauna is to be
ascribed tt) the rarity among animal sj)ecies of the power to li\'e in concen-
trated brine. Packard ascribes the phenomenal abundance of the Artemia
to the absence of enemies, for the brine sustains no carnivorous species of
anv sort. The genus is not known to live in fresh water or water of feeble
salinity, but it connnonly makes its appearance when feebly saline waters
are concentrated by evaporation. It has been ascertained that a European
species takes on the characters of another genus, Branchinecta, when it is
bred through a series of generations in brine gradually diluted to freshness,
and conversely, that it may be derived from Branclihieda by gradual
increase in the salinity of the medium. It is found, moreover, tliat its eggs
remain fertile for indefinite periods in the dry condition, so that whatever
may have been the history of the climate of the Bonneville Basin, the
present occurrence of the Artemia involves no mystery. During the Bonne-
ville epoch its ancestors may have lived in the fresh waters of the basin,
and during the epoch of extreme desiccation, when the l)ed of Great Salt
Lake assumed the playa condition and was diy a portion of the year,
the persistent fertility of its eggs may have preserved the race. Or, if the
playa condition with its concomitant sedimentation was fatal to the species,
it may be that the alternative fresh water form survived in upper lakes and
streams of the basin, so as to restock the lower lake whenever it aftbrded
favorable conditions.
THE GESTKRALi HISTORY OF BONNE VIIiLE OSCIIjIjATIONS.
We may now assemble the conclusions derived froni the discussions in
preceding chapters and in the j^receding sections of this chapter, and exhibit
a complete history of the oscillation of lake surface within tlie Bonneville
Basin, so far as it is known.
The relation of the alluvial cones to the shore-lines, and the condition
of the low passes on the rim of the basin, show that before the Bonneville
' A monograph of the Phyllopod Crustacea of North America. By A. S. Packard, Jr. U. S.
Geol. and Geog. Surv. of the Terr. 12th Ann. Kept., Part 1, 1883, pp. 295-592. Artemia graciUa on pp.
330-334.
260 LAKE BONNEVILLE.
flooding' the water level was low. This we may call the pre-Bonneville
low-water epoch. It was of great duration compared with those enumer-
ated below.
The first Bonneville epoch of higli water is stratigraphically repre-
sented by the Yellow Clay. Peculiarities of the shore-lines, and the })he-
nomena at Red Rock and other passes, shoAV that the water did not rise to
the rim of the basin and was not discharged.
After the deposition of the Yellow Clay the water subsided, and the
basin was nearly or perhaps completely desiccated. The stratigraphic evi-
dence of this subsidence is found in the unconformity betAveen the Yellow
Clay and the White Marl and in the alluvial deposits occurring at that
horizon. The possibility of complete desiccation is suggested by the differ-
ence in character between the antecedent and subsequent deposits, Avhich
difference may have been occasioned by a change in the conditions of sedi-
mentary precipitation. This may be called the iuter-Bouneville epoch of
low water.
The second Bonneville epoch of high water is represented stratigraph-
ically by the White Marl. Before the close of the epoch the water over-
flowed at Red Rock Pass, forming a channel of outflow which was excavated
to a depth of 375 feet. The Bonne\'ille shore-line records the water surface
at the date of initial outflow. The Provo shore-line records its position
after the channel of outflow had attained its maximum depth.
The existing state of affairs was brought about by the recession of the
lake surface from the Provo shore, and is stratigraphically re})resented by
the formation of local alluvial deposits on the sui-face of the White Marl.
The sedimentary deposits and shore embankments marking the high- water
stages have been more or less eroded by the modem streams, and the ancient
deltas especially have been deeply trenched. The basin has been diA-ided
into a number of minor hydrographic units. This modern epoch may be
called the post-Bonneville epoch of low water.
Nothing is known of the absohite duration of these epochs, and in the
study of their relative duration no trustworthy means has been found for
comparing a high-water epoch with a low-Avater epoch. The deposit mark-
ing the first high-water epoch is thicker than that marking the second, and
SUMMARY OP BONNEVILLE HISTORY. 261
we may hence conclude that the first epoch was the hinger, but the amount
of this difference is rendered indefinite by the fact that the base of the
lower deposit is not exposed. The comparison is further comphcated by
the difference in the two deposits, the lo^ver containing in the center of the
basin a larger per cent, of clay than the upper. If it be true that the water
was so constituted during the second flood as to precipitate a relatively
large share of the clay near the shore, and that the difference of constitu-
tion did not affect the precipitation of the calcareous matter, a time ratio
may be based upon the calcareous factors of the two elements of the
exposed section. A computation under this postulate indicates that the
first high-water epoch was not less than five times as long as the second.
Data do not exist for the quantitative estimation of the relative dura-
tion of the low-water epochs, but their order of magnitude is unmistakable.
A comparison of the few alluvial wedges referable to the inter-Bonneville
epoch with their local representatives formed during the post-Bonneville
epoch shows the former to be invariably the larger, and indicates that the
time between the two Bonneville floods was longer than post-Bonneville
time. The pre-Bonneville low- water epoch represented by the great alluvial
cones of the movmtain flanks is still less amenable to numerical statement,
in that its beginning is undefined; but it is unquestionable that it far tran-
scended in length the inter-Bonneville epoch.
It will be observed that in all respects our knowledge of the high-water
epochs is relatively definite. Not only are we able a^jproximately to com-
jiare tlie two high-water epochs in duration, but we know that on the sec-
ond occasion the water rose higher than on the first. But of the decree of
desiccation attained in the pre-Bonneville and inter-Bonneville epochs we
are practically without information. We have observed and approximately
determined two important maxima of an undulating curve, and have dem-
onstrated that they are the only great maxima of the curve; but we know
practically nothing of the remainder of the curve and are unable to indicate
the position of any minima, properly .so called.
The knowledge we have gleaned is graphically exhibited in Fig. 34,
where the upper and lower horizontal lines represent the horizons of the
Bonneville shore and the surface of Great Salt Lake. Horizontal distances
262 LAKE BONNEVILLE.
represont time, counted t'roni left to right. 'J'lie curve represents tlie lieig-lit
of tlie oscilliiting water surface, and the shaded area indicates ignoi'ance.
Fig. 34. — Rise and Fall of water in the Bonuovillo Basin.
THE TOPOGRAPHIC INTERPRETATION OF LAKE OSCILLATIONS.
(!)ne of the most important siilijects to ■wliicli the discussion of the Bon-
nevilk' history sliouhl contribute is tliat of geologic climate. The oscilla-
tions of the lake were in all })ro]iability caused ])y oscillations of climate;
and if we can satisfy ourselves as to the nature of the |)articular climatic
movements associated witia the rise and the fall of the lake, we can imme-
diatel}', by changing the notation of oin- curve, convert it into a record of
geologic climate. But in order to be fully satisfied that the curve has cli-
matic .significance, it is necessary at the outset to give consideration to other
possible modes of interpretation. For this purpose we revert once more to
the fundamental conditions controlling the size of a closed lake. The size
depends on the ratio between the suj)ply of water and the rate of evapora-
tion. Rate of evaporation is purely a function of climate; but water supply
depends quite as much on topographic configuration as on meteorologic
conditions. We are therefore called upon to inrpiire whether the water
su})ply of the Bonneville Basin may have been modified by to})Ographic
changes in such way as to account for the demonstrated rise and fall of the
lake.
It is conceivable, first, that local oscillations of land surface, or volcanic
eruption, or the Inu'sting of barriers may at one time have increased the
Bonneville drainage district at the expense of some other district, and mav
afterwards have diminished it. It is conceivable, second, that crust move-
ments may have affected the altitude of the nimuit.iins whence the wati'r
supply of the basin floAvs, in such way as to cause them to intercept a greater
share of atmospheric moisture at some times than at others. It is conceiva-
WHAT CONTEOLLED THE WATER SUITLY? 263
ble, third, that still grander crust movements have, by raising and lowering
a great area including the basin, produced corresponding modifications of
its general climate.
Hydrographic Hypothesis.-Tlie posslbility that tlic Bomievillc drainage district
has gained or lost Ijy the slow shifting of water partings or the diversion of
rivers has already been considered in the first section of this chapter; and
it is there shown that the only important changes it is admissible to postu-
late are such as affect the supply afforded by Bear River. It is quite pos-
sible that the Blackfoot, which now belongs to another drainage district,
once contributed its waters to the Bear; and on the other hand, it is quite
possible that the main trunk of the Bear was once turned from the Bomie-
ville Basin to that of the Columbia; but the first of these possibilities is
quantitatively and the second is qualitatively inadequate to explain the
Bonneville oscillations. If the Blackfoot were now to be restored to the
Bear River, there would result an increase in the area and depth of Great Salt
Lake, but such change is not to be compared in magnitude with the changes
involved in the Bonneville history ; the depth of the lake would be increased
only five or ten feet at most. If the main trunk of Bear River were to be
converted into a tributary of the Columbia a more important result would
be produced, but the Bonneville status would not be restored; on the con-
trary, the area and depth of Great Salt Lake would be diminished.
It may be added that the condition of the basaltic sheets occupying
tlie passes Ijetween the Bear River and the tributaries of the Columbia does
not indicate that they are sufficiently recent to be appealed to in ex])lana-
tion of the changes during the Bonneville epoch. There are lavas within
tlie lake area which, judged by their condition with respect to weathering,
are newer than those on the northern passes, and yet are demonsti'ably
older than the epoch of the Yellow Clay.
orogenic Hypothesis.-Thc mouutains affordiug the chief Avater supjjly of the
basin are the Wasatch and the Uinta. The Wasatch is known to have in-
creased in height, by faidting, since the last Bonneville flood, and both
ranges are known to have been somewhat u])lifted since the deiDOsition of
Neocene strata. It is highly probable that they ex])erienced upward
movements during Pleistocene time; and it is indubitable that every such
264 LAKE BONNEVILLE.
movement would result in an increase of the local precipitation and of the
consequent mag-nitude of the streams. On the other hand, it is hig-jily iin-
prohable that either of these mountains has been subject to displacements
of such nature as to reduce its height. The conjoint influence of rhythmic
upheaval and equable degradation undoubtedly produces alternate gains and
losses in altitude, and there must be corresponding gains and losses in the pre-
cipitation and outflow ; but however plausible such a hypothesis may appear
ni)()ii a merely qualitative statement, it must be regarded as quantitatively
inadequate. We have an approximate measure of the extent of the degra-
dation in the lacustrine deposits which derive their material chiefly from
that source, and we can not suppose, for example, that the removal of the
entire mass of the White Marl from the uplands at the east would sufficiently
aff'ect their altitude to diminish the water-supidy of the basin as it has been
diminished since the White Marl epoch.
There is, moreover, a general objection to any explanation appealing
to merely local changes, whether of drainage or altitude. The history of
Lake Lahontan, as developed by Russell, corresponds in a remarkable way
with that of Bonneville. It includes two maxima and two only, the first
being the longer and the second the higher.^ It is therefore in a high de-
gree probable that the phenomena have a common cause, and such cause
must be of a general nature.
Epeirogenic Hypothesis.-Tliis difficulty is oscapcd by the third hypothesis, in
which a large area, including both lake basins, is conceived to have been
siiccessively elevated and depressed to an extent sufficient to reform its
climate. Of the adequacy of such a cause there can ])e no question, l)ut we
are without evidence of its actuality. There are, indeed, in the basins of
the Columbia and Frazer, systems of terraces indicative of recent changes
in the relation of the ocean to the continent; but these serve only to indi-
cate the fact of wide-spread change and do not demonstrate sucli changes
as are necessary to account for the flooding of the Lahontan and Bonneville
Basins. If that flooding is the index of a local climate wrought ])y conti-
nental movement, the humid condition should theoretically be the result of
continental elevation and the last change should have been a subsidence;
' Geol. Hist, of Lake Lahontan, p. 237.
OPINIONS ON CORRELATION OF LAKES AND GLACIERS. 265
whereas, in the basins of the Cokimbia and Frazer, tlie hist chanjre appears
to have ])een an elevation.
Since the suggested continental movements could affect tlie lakes only
through the mediation of local climate, the hypotliesis which appeals to them
is essentiall)' a climatic hypothesis; and its further consideration may be
deferred until its proper place is reached in the discussion of the intluence
of changes in terrestial climate.
THE ClilMATIC INTERPRETATION OF LAKE OSCILtiATIONS.
OPINIONS ON CORRELATION WITH GLACIATION.
Turning now to the subject of climatic interpretation, we find an almost
universal agreement among geologists in the view that the lake maxima
were in some way associated with the history of glaciation. Tlie idea tliat
the rise of a lake contained in a closed basin is a phenomenon properly cor-
related with the formation or extension of glaciers appears to have been
independently suggested by Jamieson, Lartet, and Whitney. Jamieson,
speaking in 1863 of the climate of Central Asia,' said:
The great basin of the continental streams, larger than the area of Europe, is
remarkable for its inland lakes from whence no streams ever reach the ocean, owing
to the great heat drying up tlie water. Now this heat and dryness being much lessened
during the glacial period, there must have resulted a much smaller evaporation, which
would no longer balance the indow. These lakes therefore would swell and rise iu
level, . . .
Two years later, Lartet wrote:
Tlie level of tlie Dead Sea must therefore have been constantly regulated by the
conditions of equilibrium between atmospheric preci[iitation and evaiioration. The
extension of the waters of this lake, at a certain e[ioch, revealed by the sediments
now laid bare, which cover such vast surfaces to the north and to the s.uth of its
present limits, bears witness to a great change supervened since then iu the atmos-
pheric conditions to which the liydrograpliic regime of the country was subjected.
In the absence of fossils in the sediments anciently dei)osited by the lake, it is
impossible to assign a i)recise age to the elevation of its waters. However, taking
account of the probable duration of the phenomena which must have preceded and
followed this important phase of the history of the Dead Sea, one would be led to
attribute to it a date close to the end of the Tertiary and the beginning of the Quatei-
'Ou tlie parallel roads of Glen Roy and their place in the history of the glacial period, by Thomas
F. Jamieson, Quarterly Journal Geological Soc, Loudon, vol. 19, pp. 235-259. The passage cited
occurs on p. 258.
266 LAKE BONNEVILLE.
nary poriod. Ono would thou bo alilo to soo in tliis riso of tlic, surface, of tlio lake an
ettect of the glainal plieiiomeiia whose, iritliieiice seems to have extiMidecl, at tliese
epochs, to ueighboriug resioiis. Tliis, inor(M)ver, would accord ipiite well with the
observation of traces of ancient moraines which Dr. D. Hooker tliought he recognized
on the slopes of Lebanon.'
Only a few months later, Whitney, treating, in the first volume of the
Geology of California, of the former extension of ^Mono Lake, said:
Whatever cause gave rise to the immense body of ice, in the form of glaciers,
which, as we have seen, formerly covered the summit of the Sierra in this region and
extended down for 5,000 feet or more from the crest, this would undoubtedly have
been snfticient to siipi)ly water enough to raise the lake to the height which the ter-
races about it show that it must once Iiave liad.-
It is not certain tliat he adheres to this view at present, for in his
memoir on the Climatic Changes of Later Geological Times (1882), he
characterizes the glaciation of the Sierra as an episode (p. 2), but regards
the desiccation of the Great Basin as a continuous process of which the
beginning dates far beyond the Pleistocene. On p. 190 he says:
Before advancing another stage in our discussion, however, we have to make it
clear that the diminution of the rivers, the disappearance of the lakes, and all the other
phenomena indicative of a gradual but persistent tendency to aridity over vast areas
once fertile and well watered, do not form a transient i)hase of a precedent Claeial
epoch, but are the result of some cause which began to act before that period, and is
still continuing without any connection with it.
In my original description of Lake Bonneville I argued its correlation
with the Pleistocene Period in the following language:
The Bonneville epoch and the Glacial epoch were alike climatal episodes, and
they oci urred in the same general division of geological time, namely, the division of
which modern time is the immediate sequel. If it can be .«hown that the climatic
changes were of the same kind, there need be no hesitation in assuming the identity
of the epochs. The glacial climate we commonly regard as merely cold, and a low
temperature was doubtless its chief characteristic; but it admits, ne ertlieless, of
another view, The climatic comlition essential to the formation of glaciers is, tint
the summer's heat shall be inadequate to dissipate th(> winter's snow, and this may lie
brought about, either by a lowering of temperature, or by an increase of winter pre-
ci[)itatio;i. The jirofuse |)recipitation of our northwestern coast woultl maintain s'leat
glaciers if the climate were cold enough; rivers of ice would follow the higher valleys
of the Rocky Mountains if the snow-fall were heavy.
'Louis Lartot, Comptcs Roiuliis <lo rAcaddniio ilcs Sciouces, Paris, St^anco du 17 Avril, 18Go.
Vol. CO, p. 798.
Seo also Hull, de la .Soc. Gfi.o\. do la Frauic, '2(1 sftric, vol. 22, p. 4,")7 ; Si'aiuo <lu 1 Mai, 186.5.
«Geol. of Cal., vol. 1, p. 452.
OPINIONS ON CORRELATION OF LAKES AND GLACIERS. 267
To account for the origin of Bonneville Lake, we need to assume a climatal
change, that would increase in-ecipitation, or diminish evaporation; and both of these
ctlVc's would follow, in accordinici^ with familiar meteorological laws, if the luiiiiidity
of the air were increased, or if the temperature were lowered. There can be no doubt,
then, that the great climatal revolution, which covered our northeastern States with
ice, was competent to flood the dry basin of Utah; and that it actually did so is at
least highly probable.'
In volume 1 of the Fortieth Parallel report (1878) King- classified Lake
Lahontaii as well as Lake Bonneville as a phenomenon of the Pleistocene
or Quaternary period, and argued that their basins were di'y at the beginning
of the period. In the case of Lake Lahontan, from a discussion of the
chemical history of a, jjcculiar pseudomorijh, thinolite, lu; drew the conclu-
sion that the basin was flooded twice instead of once, the first flooding hav-
ing "an enormously long continuance as compared with the second." He
further concludes:
The first long-continued period of humidity is jirobably to he directly correlateil
with the earliest and greitest Glacier period, and the second period of humidity with
the later Ri'indeer Glacier period.
The Quaternary lakes of the Great Basin are therefore of extreme importance in
showing one thing — that the tw(j glacial ages, whatever may have been their temi)er-
ature conditions, were in themselves each distinctly an age of moisture and tl at
the interglacial period was one of intense dryness, eciual in its aridity to the jiresent
epoch .^
I afterward discovered the evidence of the inter-Bonneville epoch of
low water, and thus demonstrated the duality of the Bonneville flooding.
Announcing this discovery in the First Annual Rej^ort of the U. S. Geolog-
ical Survey (p. 26), I say:
If it be true, as argued by Mr. King and the writer, that the Bonneville epoch
was synchronous with the glacial epoch, then it may also be true that the subdivision
of the glacial epoch into two subepochs, with an interval of warmth, finds here a
manifestation.
Subsequent investigations in the Lahontan basin by Russell serve to
call in, question King's conclusions in regard to thinolite, but independent
reasons were found for afiirming the double maximum of the lake stirface.^
Peale, who examined the Bonneville sediments in Malade and Cache
Valleys, does not discuss their relation to glaciers or climate, but may per-
'Explor. West of the lOOfli Meriilian, vol. :? ji. 97.
2Geol. Expl. 40th P.TraUel, vul. 1, p. 524.
= Thir(l Ann. Rept. U. S. Geol. Survey, pp. 2-20-222; Geol. Hist, of Lake L,ahontau, pp. 250-2G8.
268 LAKE BONNEVILLE.
Imps be considered to im))ly a eon-elation, in tiiat lie refers them to the
Pleistocene.'
A nnicpie view of the siiliject entertained by Endlich can not be
igiiovcd in this connection, and, since it is found necessary to dissent tliere-
froin, fixirness seems to require its presentation somewhat fully in his own
language. Speaking of the ancient glaciers of the mountains of (Colorado,
he says:
If we study the country adjacent to tliat where we find glacial evidence, we will
ooserve that a by far larger area was at one time covered by water than to-day.
The Great Salt Lake extended beyond^ the boundaries that now confine it, * * » •
Here, then, we have a source of moisture far exceeding, in quantity, that carried east-
ward at present by the prevailing westerly winds. * » • i conclude, therefore,
that the ancient glaciers of Colorado and regions similar to it, both as regards geo-
graphical location and orographic construction, owe their former existence mainly to
the presence of those numerous sheets of water farther west. These have now disap-
peared, and incident upon their removal, whatever may have produced that, was tiie
recession and final extinction of the ancient glaciers. Holding this view, I maintain
that the lakes formerly filling so many valleys were in existence before any glaciers
occurred in the Rocky Mountains proper. * * * It is highly probable, however,
that the i)eriod of their greatest magnitude fell into the time of the general glacial
ei)Och.^ » # #
A fiital difficulty here is a failure to recognize the fundamental dif-
ference between closed and drained basins in their relation to the moisture
of the atmosphere. Closed basins return to the air just as niucli water as
they receive from it; drained basins do not. The -prevailing westerly
Avinds to which he refers sweep across the hydi'ographic district of the Great
Basin before reaching the momitains of Colorado. At the present time the
moisture they discharge in crossing the Great Basin is precisely equal to
that which they absorb, so that they approach Colorado with huniiditv
unchanged. When Lake Bonneville and some other lakes of the basin
were so filled as to overflow to the ocean, the preci.se amount of their dis-
charge was abstracted from the westerly winds in their passage, so that the
winds left the district of the l^asin drier tlian they entered it. If the air
currents reaching the Colorado Mountains from the west were tlicii moistcr
■ Dr. A. C. Pealc in Ann. Rei>fc. U. S. G. & G. Snrv. of Terra, for 1877, p. 641.
2 Dr. F. M. Endlirh ; Ann. Kept. U. S. G. «fc G. Snrv. of Terrs, for 187.-), p. S25.
REGENCY OF LAKES AND GLACIERS. 269
than now, their humidity must have been acquired before they reached the
district of the hxkes.
THE ARGUMENT FROM ANALOGY.
Reverting- now to the correlation of lacustrine and glacial phenomena,
as suggested and developed by Jamieson, Lartet, Whitney, King, Russell,
and myself, the data on which the correlation is based will l)e examined in
detail. Up to the present time all reasoning on the subject has been
based upon analog v. The identity of the two classes of phenomena in time
and cause has been inferred, tirst, from their recency; second, from their
exceptional nature; third, from the parallelism of their recurrence; and,
fourth, from the belief that it is possible to account for them by the same
modifications of climatic conditions. These elements of analogy will be
taken up in the indicated order.
Recency.-The reccncy of the lacustrine events and the recency of the
glacial events are severally inferred from the excellent preservation of their
vestiges. The atmospheric agencies which sculpture the land, rapidly oblit-
erate all topographic features which do not conform to their types, and they
attack with especial vigor masses of unconsolidated material which stand in
relief. The embankments of the ancient shore-lines and the moraines of the
ancient glaciers agree in their susceptibility to rapid modification by erosion,
and they agree in exhibiting a condition of almost perfect preservation. In
the case of the moraines, this remark applies onlj- to those which were latest
formed; but it is these which can most properly be compared, for the earlier-
formed shore embankments are not visible, having been overplaced by those
of later date. The recency of phenomena thus demonstrated is qualitative
merely: So far as we are able to interpret the evidence from preservation,
the embankments may be twice as old as the moraines, or the moraines
twice as old as the embankments.
Episodai character.-Tlie exccptional iiaturc of the Pleistocene glacial phe-
nomena is generally recognized, and is illustrated in a striking manner in
the immediate vicinity of the Great Basin. As first pointed out by Whit-
ney, the great glaciers of the Sierra Nevada occupied an antecedent system
of valleys, shown by their form to be the product of stream erosion. The
270 LAKE BONNEVILLE.
period of ice was therefore preceded by h period wlieii tlii're was no ice, or
little ice, and this antecedent period was of relatively great duration.
The episodal nature of the lacustrine j)lienoraena of tlie Great Basin
has been recognized by all ol)servers, with tlie possil)le exception of Whit-
ney; and the evidence in relation to the Bonneville Basin has been full}' set
forth in the preceding pages. The pre-Bonneville period was characterized
by ariditv, and it was long as compared to the Boinieville period. Tlie
formation and extension of glaciers and the formation and extension of lakes
have thus the common character of episodes, interrupting a course of events
\\'hich was resumed after their disappearance.
Bipartition.-A tlurd polut of aualogy is parallelism of reciiiTence. The
history of Lake Bonneville and the history of Lake Lahontan have been
independently shown to be bipartite, and the similarity of the series of
oscillations in the two basins gives great contidence to the conclusion that
they were synchronous. If it be true, as believed by many geologists, that
the history of the glacial period is similarly bi2)artite, the argument in fa\dr
of the synchronism and the common origin of the lacustrine and glacial
phenomena acquires great strength. It is pertinent, therefore, to inquire
what support the belief in a double glacial period finds in the facts of obser-
vation ; but since this inquiry Avould involve too great a digression from
the subject in hand, attention will be limited to the t^uestion of the support
the belief finds in the opinion of those most competent to discuss tlie
phenomena.
It is to be observed at the outset that a Ijelief in the double nature of
the glacial epoch implies a belief in its actuality as a general phenomenon
of geologic climate. If the truth lies with those who aflinii that the ancient
glacial phenomena depend upon strictly local conditiinis, and are not widely
synchronous,' it is evident that the bipartition of the plieiionieiia can not be
general, and that the only analogy pertinent to the present incpiirv would
arise from the discovery of evidence of recurrent glacial extension in the
mountain ranges which border the Great Basin. Reference will be made
' See J. D. Whitney, Climatic changes cit later Geological Time: Mem. >Siiseum of Compariitive
Zoology, vol. 7, No. 2, pp. 191, 21)8, :!«7; J. F. Campbell, Glacial periods; Quart. Jonrn. Geol. Soc.
Loudon, vol. 35, p. 9K; Rev. James IJrodie, On the action of Ice in what is usually termed the Glacial
Period : Brit. Ass. Rep't, 1875, p. 63. (Sections.)
EUEOPEAN OPINIONS ON CIPAKTITION. 271
ill the sequel to a I'riigment of local evidence of this nature; but attention
•wiW at present be restricted to the testimony in regard to a general duplica-
tion of glacial history. The tendency of the testimony will be sufficiently
indicated l)y citing those conclusions of held geologists whidi appear to
represent the liroadest survey of phenomena and to be least hampered l)y
general theories.
Penck, who has studied the glacial phenomena of the northern face of
the Alps, has supplemented the presentation of his own results l)\' a histori-
cal digest of those of his predecessors.' He confirms the recognition by
Morlot and others, of two great advances of the glaciers, and announces
traces of a third. The greatest advance occurred in the second of the three
ice epochs, and the least advance in the first.
Briickner, likewise a student of the northern face, agrees with Penck
in recognizing three epochs of glaciation, but he considers the first advance
slightly greater than the second and the third least of all."
French geologists who have examined the western portion of the Alps
are practically unanimous in asserting the unity of the phenomena. Falsan
admits more or less protracted phases of progression and recession of the
old glaciers, but denies the existence of any adequate evidence of an inter-
glacial period.^
Those who have given special attention to the southern or Italian slope
of the Alps are divided in opinion. Sto})})ani and Gastaldi regard the gla-
cial period as a unit,^ while Taramelli distinguishes two phases of glacial
expansion, separated by a long interval marked by hydrographic changes
and slight oscillations of level.^
James Geikie recognizes no fewer than four glacial epochs, separated
by intervening epochs of mild climatic conditions." In the English deposits
'The Glaciatiou of tbc German Alps. . . . By Dr. Albrecht Penck. pp. 220, ^61, 311, :5->2.
-Die Eiszeit iu deu Alpeu. vou Dr. Eduard Briickner. Mittheil. Geogr. Gesell. Hamburg,
1887-88, pp. 10-12.
^A. Falsan, Esquisse gdologique du terrain errati(|ue et des anciens glaciers do la region ceutralo
dn bassin du Rhone. Lyon, 1883. (Cited at second band.) Also, La piSriode glaciaire. Paris, 1889,
pp. 24-2-245.
■■A. Stoppani, Geologia d'ltalia, Part 2, Milan, 1880. Gastaldi, Realo Accademia delle Scienze di
Torino. Atti. 1872-73. 8°. Page 410, " Appuuti sulla Memoria del Sig. Geikie F. R. S. E , On changes
of cliiiinte during the glacial epoch."
sTaramelli, Atti della Reale Accademia dei Liucei, 1881-82, 3d series, vol. 13. Roma, 18S2, p. 508.
^Prehistoric Europe, p. 2G5
272 LAKE BONNEVILLE.
the first <j;lai-ial epoch is rc])r('sciitc(I 1)\- tlic ( 'roinci- I'lay, the second hy the
ijreat chalky ])OAvhhM- clay, the fluid 1)\ tlic piirphi clay of Iloltlorness, am]
the fourth l)y the Hessle Clay. In Hcotlaiid, France, GeiTQauy and Scan-
dinavia the series of de})osits are less perfect.
Archibald Geikie, having before him the same evidence, recognizes for
England and Europe generally only two glacial epochs, the glaciers of the
second T)eing smaller than those of the first and to a greater extent local.
He recognizes also the iiiterru})tion of the first l)y warmer epochs, re})re-
seuted by interglacial beds, but these do not with liini constitute an element
of the })rimary classification.'
In northeastern Iowa, the stratigraphy of the superficial formations
has ])een studied by McGee, avIio deduces the following history. First, the
extension of the northern ice over the region; second, its withdrawal "and
a period of nnldclimatal conditions which nnist have been of innnen.se dura-
tion"; third, a second and last great glacial advance; fourth, a tliird slight
advance of the ice, of which indirect results only Avere observed in north-
eastern Iowa." The formation representing the long interglacial period is
a "forest bed", a ligneous stratum separating two deposits of till. An equiv-
alent forest bed in Ohio has been interpreted by Newberry in the same
way.^
Upham, whose most important personal studies were in Minnesota and
adjacent parts of Dakota and Manitoba, distinguishes "two principal glacial
epochs . . . each sul)divided by times of extensive recession and readvance
of the ice . . . A long period intervened," during whicli the ice proliably
retreated as far as Hudson Bay.*
Chamberlin, whose studies of American glacial ])henomena have been
exceptionally comprehensive, gives the following generalized talilc of Pleis-
tocene fonnations and events.*
'Text Book of Giiology, 1S82, pp. 83.->-8;i3, 896.
-On thu complete series of Su])erlici;il Formations in Northeastern Iowa. Hy W. ,J. MeGee. Proc.
.\ni. Ass. Adv. Sci. vol. 27, 1879, pp. 198--,':il.
•'Tlie Drift Deposits of Indiana, l),v J. S. Newberry; in lllli .\nn. Kep. (ieol. and Nat. Jlist. of
Indiana, by .John Collett, 1884, p. 90.
■•Warren Upluuii; Proc. Am. Ass. Adv. Sei. vol. :52. 1884, pp. SJ-J, 223. See also Geol. and Xal.
Hist. Snrvey of Minnesota, vol. 1 of Final Kept., 1884, pp. 40(i, 481, .'■)80.
*Tlie Driftless Area of the Upper Mississippi. By T. C. Chamberlin and R. D. Salisbury. Sixth
Ann. Kept. U. S. Geol. Survey, 188"., p. 212.
AMERICAN OPINIONS OF BIPARTITION.
273
Epochs.
Sabepochs or Episodes.
Attendant or characteristic phenomena.
Not yet sati-'^factorily dis-
tinguished from the Plio-
cene.
First aubepoch or epj.'iode.
^ Interglacial subepoch or
episode of doglaclation.
Sucood subepoch urepisode -
Drift sheet with attenuited border; absence or
nieagerness of coarse ultra-marKiual drainage
drift.
Decomposition, oxidation, ferrugination. vegetal
accumulation.
Drift sheet with attenuated border; loess contem-
poraneous with closing stage.
Elevation of the upper Mississippi region 1.000±
feet. Erosion of old dritt, decomposition, oxida-
ti'tn, ferrugination, vegetal accuniulatious.
Till sheet bordered by the Kettle or Altamont
moraine.
Vegetal deposits.
Till sheet bordered by the Gary moraine.
Till bordered by the Antelope moraine.
Marked by teiminal uiuraines ot undetermined
importance.
Marine deposition in the Champlain and Saiot
Lawrence valleys and on Atlantic border; lacus-
trine deposits about the Great Lakes.
Marked by fluvial excavation, uotahly of the flood
plains of second glacial epoch.
n. Earlier j;lacial epnch
III. Chief interglacial epoch
IV. Later glacial epoch
First episode or subepoch - -
Episode of deslaciatiou ..
■^ .Second 8t;ign or suhepoch .
Episode of deglaciation
1 Third episode
VI. Terrace epocli
According to Newberry " there were two maxima of cold separated
by a long interval in wliich the climate was ameliorated"; but this climate
was still cool, and the ice probably did not retreat far beyond the Great
Lakes/
While the conclusions of McGee, Upham, Chamberlin and Newberry
are based jjrimarily on studies in contiguous districts, include to a large
extent the same phenomena, and agree in recognizing two maxima of cold,
those of Chamberlin and Upham are the only ones in complete accord.
Newberry differs from the others in that he regards the inter-maximum ics
retreat as relatively small. Chamberlin and McGee, agreeing that glacia-
tion was interrupted by a long epoch of warmth, and that it was also varied
by episodes of local or temporary retreat of the ice sheet, differ in their ref-
erence of an important bed of till, and hence draw differently their lines of
primary classification. McGee's interglacial period "of immense duration"
is Chamberlin's "interglacial subepoch or episode of deglaciation ", and
McGee's " second and last great glacial advance " is Chamberlin's " second
subepoch " of the " earlier glacial epoch."^
By later investigation McGee finds evidence as to epochs of cold in the
]ilienomena of the deposits and erosions of the Atlantic border south of the
Drift. From this investigation he concludes that the Pleistocene included
'Nortb America in the Ice Period. By John S. Newberry. Pop. Sci. Monthly, vol. 30, 1886, p. 9.
^See McGee in Am. Jour. Sci. :{(1 series, vol. 35, 1888, pp. 458-461.
MON I 18
274 LAKE BONNEVILLE.
two and only two great epochs of cold ; that tliese epochs were separated
by an interval three, five, or ten times as long as the i)ost-glacial interval ;
and that the earlier cold endm-ed mnch the longer and was the less intense.'
These inferences are harmonions either with Chanil)erlin's conclnsions or
with his own results in Iowa, taken separately, and they correspond closely
with my reading of Bonneville history; by substituting the terms "wet"
and "lacustral" for "cold" and "glacial," the Bonneville story can be
summed up in tlie same words as McGee's story of the Atlantic border.
Wright early advocated the unity of the period of glaciation in America
and still adheres to tliat view. In a recent publication he states that " most
of the facts adduced to support the theory of distiiict epochs are cajiable of
explanation on the theory of but one epoch with the natural oscillations
accompanying the retreat of so vast an ice-front."^
The latest word on the subject is from James Geikie,' whose digest of
results obtained by geologists of continental Europe comes to hand \\hile
these pages are in proof The plain of northern Germany was twice over-
run by the Scandinavian ice sheet, and experienced a temperate climate in
the interval. Students of Alpine di-ift recognize more than two epochs of
glacier extension, and it is possible that the interglacial deposits of the
northern plain do not all belong to the same interglacial epoch.
From this summary of opinions it aj)pears that the relatively simj)le
conception of Pleistocene history which belonged to the early stages of its
investigation has been generally replaced b}- the \"iew that its climate was
characterized by great oscillations. This result has been reached separately
and through independent methods by European and American students.
l)ut while the fact of oscillation is widely accepted for each continent, the
progress of investigation seems not yet to have rendered the two histories so
definite that the question of their similarity and svnclu'onism can profitably
be discussed. Whatever confidence we may have that the Plei-stocene gla-
ciation was a recurrent phenomenon, it must be admitted that ])arallelism
of recurrence remains to be proven. It follows that, for the present at least,
' Am. Joiir. Sci. 3d series, vol. 35, la-'H, p. 403.
■^Tho Ice Age in North America. By G. Froilerick Wright. New York, l!J89, p. 500.
'Address to the Geological section of the B. A. A. S., September, 1889.
GENETIC CORRELATION OF LAKES AND GLACIERS. 275
parallelism of recurrence can not with confidence be ajipealed to in tlie
correlation of the lacustral history with the glacial history.
Genetic correiation—Tlic fourtli point of analogy is genetic. It is generally
believed that any climatic change competent to restore the g'laciers of Cali-
fornia and Utah would likewise restore the ancient lakes of the Great Basin.
From this belief there has been no dissent, and it is certainly plausible ;
but it must nevertheless be admitted that meteorology in its present stage
affords it no satisfactory basis. Tlie general subject of climate is highly
complex, and Its laws are not so well understood that the results of new
combinations of conditions can be foretold.
The size of lakes and the size of glaciers are determined by three
processes :
A. Precipitation of rain and snow.
B. Evaporation of water, snow and ice.
C. Melting of snow and ice.
The essential elements of local climate upon which the local I'ates of
these three processes depend are at least four in number, and may conven-
iently be indicated under five heads :
(rt) The temperature of the air.
(b) The vapor tension or vapor content of the air, or the temperature
of the dew point.'
(c) The general velocity of the wind.
(d) The degree of cylonic activity ; and finally,
(e) The variation of these, and the distribution of their variations
through the year.
' For the iintechnical reader, these terms may stand in need of deliuition. The invisible moist-
ure contained in the air is called aqueous vapor, and has the properties of .a gas. By virtue of its
elasticity it exerts a certain tension, and this tension is the measure of the amount pretsent at any
point. Vapor tension and ra^jor coH(eH( are therefore synonymous. The amount of moisture .air will
hold without condensation is limited, and the limiting amount varies with temperature. For each
temperature there is a maximum vapor tension known as the tension of saturation ; for each vapor
tension there is a minimum temperature known as the drw point. The temperature of the dew point
at any place and time is thus an index of the existing vapor tension. Relative humidity is the ratio of
the actual vapor tension to the saturation tension corresponding to the actual temperature ; it is the
humidity reckoned in terms of saturation as unity.
276 LAKE BONNEVILLE.
The move general terrestrial conditions wliich immediately determine
these local elements may likewise be enumerated under five heads. They are :
(1) The latitude of the locality.
(2) Tlie altitude of the locality, and the system of altitudes in its
vicinity.
(3) The distribution of land and water in a very large district includ-
ing the locality.
(4) The system of currents in oceans within this district (a function
of 1 and 3).
(.O) The wind dfrection (a function of 1, 3, and 4).
Directly or indirectly, each of these five conditions affects each of thfe
five elements of local climate, so that there is a most intricate plexus of cause
and effect. In a qiialitative way much is known of the nature of these
relations, but quantitatively very little is known. It i.s perhaps fair to say
that the relations of temperature and humidity to latitude and altitude are
the only ones whose numerical laws have been successfully investigated,
either theoretically or empirically. Gradually the various climates of the
earth are being explained and referred to their proximate causes; but the
time has not come when the meteorologist can trace out the quantitative
relations, or even in any fullness the qualitative relations, of a specific
hypothetic change in one of the conditions of climate. Such a pr(il)lcni
as the distribution of climates if the direction of terrestrial rotation wvre
reversed can at present be solved only in a very rude way.
In the presence of such complexity, theories are nec^ssaril}- based upon
partial views, and the hypothesis or opinion that the magnitudes of enclosed
lakes and of glaciers are similarly aftected by climatic changes ajjpi'ars to
depend upon such a partial view. This was certainly tlu' case when I
advanced the opinion in an earlier paper.
Let us assume that in the region of the Great Basin and tlic surround-
ing mountains the aqueous vapor, the wind v(■lo(•it^•, the cvclonir activity,
and the annual oscillations of these climatic elements remain constant, while
tlie tenq)erature alone undergoes variation. The cause of the tenqierature
change lies of course in a modification of some climatic condition, and such
modification would necessarily have its effect upon vapor, wind velocity,
EFFECT OF LOCAL TEMPERATURE CHANGE. 277
etc., but this effect is by the present assumption ignored. Conceive, first,
a hiwering of local temperature. The vapor tension remaining the same,
the relative humidity of the air would be greater than at present; and
cyclonic activity remaining the same, the increase in relative humidity would
cause increase in precipitation of rain or snow. The wind velocity remain-
ing the same, the lowering of temperature would retard evaporation, a
smaller share of the moisture precipitated on the land surfaces of the Great
Basin would return to the air, and a larger share would gather in streams
and flow to the lakes. Evaporation from the lake surfaces would be sloAver,
and the lakes, with increased supply and diminished dissipation, would grow
deeper and broader, just as they did of old. In the mountains the lower-
ing of temperature would increase the length of the season during which
precipitation takes the solid form, and a greater proportion of the total
precipitation would be in snow. The increased relative humidity of the
atmosphere would occasion a greater total precipitation, and the winter's
accumulation of snow would thus be doubly augmented. The same cause
would diminish the annual evaporation of snow, and the shorter and cooler
summer would have less melting power. In every way the accumulation
of snow and ice would be promoted and its dissipation checked. The small
glaciers which hang about some of the highest crests would wax in size and
others would reoccupy the empty cii'ques, until finally a broad mantle of
snow and ice would cover the high district of the Sierra, and ice streams
would flow to the valleys on either side, just as of old.
Conceive now a rise of local temj^jerature. Tlie relative humidity of
the air would be less than at present; the precipitation in rain and snow
would be less; the evaporation would be more rapid, antl a smaller share
of the diminished precipitation would gather in streams and flow to. the
lakes. The lakes, with decreased supply and increased dissipation, would
grow shallower and smaller. In the mountains the winter would be shorter,
and a smaller share of the diminished precipitation would take the form of
snow. The evaporation of snow would be more rapid, and the longer and
warmer summer would have greater melting power. The supply of snow
wovild be diminished and its dissipation would be promoted. The existing
small glaciers would disappear.
278 LAKE BONNEVILLE.
Let us now assume that in the same region the temperature, wind
velocity, etc., remain constant, while the vapor tension alone undergoes
variation. Conceive, first, an increase of local vapor tension. The tem-
perature remaining the same, the relative humidity of the air is increased,
and this increase in relative humidity causes increase in precipitation of rnin
and snow. It induces also a slower evaporation. The supply of water to
the lakes is increased, their superfcial waste is diminished, and they grow
in size. On the mountains the snowfall is increased, though its period remains
the same. The dissipation of snow by evaporation is less, the melting of
snow l)y direct insolation is sensibly unchanged, l)ut its melting by sunmier
rains is accelerated. In the region of the Sierra glaciers the sunnner pre-
cipitation is so small as compared with the winter that this last factor can
not be important; and we need not doubt that accumulation of snow would
exceed dissipation, causing an extension of the glaciers. Conceive now a
diminution of vapor tension. The preceding relations are evidently reversed.
The lakes of the Great Basin receive less from the streams and part witli
more to the air, and therefore shrink. The glaciers of the Sierra receive
less snow, lose more by evaporation and lose slightly less l)y melting, and
they will therefore shrink.
It thus appears that a local change in temperature alone or a local
change in moisture alone would cause the lakes of the Great Basin and the
glaciers of the Sierra simultaneously to enlarge or simultaneously to con-
tract. But wdien Ave consider their concurrent change, no such definite
conclusion is possible. If rise of temperature is accompanied bA- diminu-
tion of vapor tension, there will be a common shrinkage of lakes and
glaciers, for these climatic changes have the same tendency. Similarl\-, if
fall of temperature is accompanied by increase of vapor tension, lakes and
glaciers will grow; but a rise of temperatin-e and an increase of vapor, or
a fall of temperature and a decrease of vapor, will have antagonistic efiects
upon both lakes and glaciers, and the nature of their resultant can not be
determined without quantitative data. We need greatly to extend our
knowledge, not only of climatic laws, but of the climate and phvsical
geogra})hy of the Great Basin, to enable us to determine wliar increase of
vapor tension is adequate to neutralize the effect of one degree's rise of
^
EFFECT OP LOCAL HUMIDITY CHANGE. 279
temperature upon the size of the hikes; and we need in addition greatly to
extend our knowledge of the climate of the Sierra Nevada to enable us to
determine what increase of vapor tension will neutralize the effect of one
degree's rise of temperature upon the size of the glaciers. It is only in
the case that these two increments of vapor tension are equal, that increase
of lakes and increase of glaciers will be invariably coordinate. If they
are unequal, then it is possible to assume simultaneous changes of tempera-
ture and vapor tension under whose influence the lakes will expand, while
the glaciers shrink, and vice versa.
But this view of the case is still only partial. Any change in the alti-
tude of the district, in the position of the adjacent coast of the Pacific, in
the nature of the currents of the North Pacific, or in the direction of the
prevailing wind, would not only modify the temperature and humidity of
the district under consideration, but would affect the wind velocity, the
cyclonic activity, and the cycle of annual climatic change. A variation of
wind velocity Avould make itself felt in the rate of dissipation of lakes and
glaciers; a variation in cyclonic activity would manifest itself in the supply
of Avater and .snow to lakes and glaciers; and a variation in the anmial
cycle of climate might affect lakes and glaciers not only miequally but
diversely.
Too little is known of these last mentioned influences to warrant any
attempt to discuss them here. For this reason, and for this ouh', they will
be ignored in the following paragraphs; but it is understood that the con-
siderations about to be advanced are subject to whatever modification -^ev-
tains to the omitted factors. Restricting attention to the two elements of
local climate, temperature and vapor tension, we will now endeavor to
ascertain how the lakes and glaciers of the district would be affected through
them b}' various postulated changes of climatic conditions.
Let us inquire, first, what will result from a general change of altitude,
or more specifically, from a bodily uplift of the entire district, including
the Great Basin and the adjacent mountains. It is Avell known that both
temperature and A-apor tension are inverse functions of altitude; the tem-
perature of the district will be lowered by the uplift, and the moisture
normal to the new altitude will be less. The atniosphere covering- this
280 LAKE BONNEVILLE.
distru't is part of a great eastward-tending current which derives its moist-
ure from the North Pacific Ocean. The hypothetic change of altitude will
not affect its humidity where it enters the district. Its vapor tension can
be reduced to the noniial only by precipitation, and if not thus reduced,
there will l)e an increase of relative humidity, owing to the lowering of
temperature. We shall have, then, for the district, either an increase of
precipitation or an increase of relative humidity. The former woidd aug-
ment the supply of Avater for the lakes and of snow for the glaciers; the
latter woidd retard evaporation and thus diminish the waste of water and
ice. The loAvering of temperature likewise will not only retard evaporation,
but will retard melting, and will extend the season in which precipitation
takes the form of snow. Thus, in every way, the growth of lakes and
glaciers will be favored. Conversely, a general depression of the district
will diminish lakes and glaciers.
Let us inquire, in the second place, how the climate will be affected by
changing the distribution of land and water. Evidently, the number of
different changes which might be postulated is unlimited, but there is one
particular change to which the district is peculiarly sensitive, and which
may stand for a large class. This change is an eastward or Avestward move-
ment of the coast line of California, so as to diminish or increase the belt
of land between the Sierra Nevada and the ocean. Let us postulate a west-
ward movement, or an increase of the land. The general movement of the
atmosphere in this region is from the ocean to the land, and the moisture
gathered from the surface of the ocean is the store whence all the precipita-
tion of the land is derived. The addition of a belt of land will inci-ease the
area of uncompensated precipitation, and will thus duninish the general
vapor tension of the atmosphere of the district. It has been pointed out by
Button,^ that the portion of the ocean under consideration has a temjierature
lower than the normal for the latitude, so that the air current grows warmer
in passing over the land. The intervention of an additional belt of land
will add its quota of heat to the air, and thus render the general tempera-
ture of the district higher. An addition to the coast will therefore induce
'On the cause of the arid climate of the western portion of the United States, by Capt. C. E.
Uutton, Am. Jour. Sci., :!d scries, vol.22, p. 247. See also, Haun's Handbuch der Klimatologie, p. 13(>.
EFFECT OF HYPOTHETIC OCEANIC CHANGES. 281
a diminution of vapor and a rise of temperature, and these changes, as we
have .seen, are competent to diminish lakes and glaciers. The reverse effects
\\ ill of course be wrought by a dimiiuition of the coast area.
Tliird, let us endeavor to see how our district would be affected by a
moditication of ocean currents, The influence of such currents u^ion cli-
mates is exerted through their temperature; and we will postulate a rise in
the temperature of the current which follows the coast of California from
north to south. A warmer ocean will give a higher temperatvxre to the land-
ward-flowing air, and at the same time impart to that air a greater load of
aqueous vapor. Since the oceanic district in question is now cooler than
the land district whose atmosphere it tempers, a warming of the ocean will
tend to diminish the contrast of temperatures. The warming of the air
during its landward progress will therefore be less, and there will be a
tendency towards a higher relative humidity. Precipitation will thus be
promoted. Evaporation will be favored by the higher temperature, but
opposed by the higher relative humidity; and it is not easy to see which
tendency will prevail. The melting of snow and ice will be promoted both
by the higher temperature and by the greater length of the summer, while
the winter, or the season in which precipitation takes the form of snow, will
be shortened. So long as only a small change is considered, the merely
qualitative statement does not clearly show whether the increased rate of
snowfall will he more or less than compensated by the increased rate of
melting; and the uncertainty in regard to evaporation leaves us in doubt
whether the lakes will swell or shrink.
If, however, we pass to an extreme case, there is no room for doubt.
A great increase of oceanic temperature, say ten or twenty Fahreidieit
degrees, would reverse the contrast of temperature between land and shore.
The eastward-flowing air, instead of being warmed by the land, would be
cooled; and the resulting pi-ecipitation would far surpass any possible in-
crease of evaporation. The Great Basin would become a basin of great
lakes. The same temperature change would so abridge the winter season
in the mountains, and so enhance the melting power of the sunuuer, that no
glacier could possibly survive. The converse follows.
282 LAKE BONNEVILLE.
Finall|)', let us ask what will result from a change iu the direction of
the generixl air current. This direction belongs to the great syst^jin of
atmospheric circulation, and a large change is practically out of the ques-
tion. We are at liberty, however, to assume small changes, based upon
local conditions; and -we A\ill |)ostulate that the wind becomes more south-
erly. With such a course, it will derive its temperature and moisture from
a portion of the Pacific Ocean warmer than that now traversed by it; and
the ])rincipal effects in the mountain district under consideration will be
identical with those deduced in the last paragraph, as resulting from a
warmer ocean. Minor effects will be conditioned by the configuration of
the belt of land traversed by the wind before reaching the interior district,
and the distribution of climate within the district will be modified; but the
probable importance of these considerations is not sufficient to warrant
their discussion.
It appears, then, that lakes and glaciers would simultaneously increase
if the district as a whole Avere to be uplifted, or if the Pacific Ocean were
to encroach upon the California coast; and the conclusion is less confidently
reached that the lakes of the Great Basin would increase, and the glaciers
of the Sierra Nevada decrease, if the North Pacific Ocean Avere wanner, or
if the coastward Avinds traA'ersed a Avarmer tract. But the subject is by no
means exhausted. We mig-lit consider the various combinations of these
four postulated changes of condition, or, going beyond them, Ave might turn
our attention to those more remote causes of change to Avliirh theories liaA-e
appealed in explanation of Pleistocene glaciation. Whether Ave attempted
to trace out the consequences of far-reaching geographic changes, of varia-
tions in the eccentricity of the earth's orbit, or of the terre.striid \\ andcring
of the earth's axis of rotation, Ave should equally find ourseh-es iuA-olved in
a maze of complexity, and ultimately brought face to face Avith the imjier-
fection of the science of meteorology.
RevieAving the innnediately preceding discussion, avc see that tlu' partial
view Avhich takes account of temperature onh', or of a(pie(ius \apor only,
results in a definite conclusion. The Ijmadcr but still partial aIcw wliicli
takes account of temperature aud iupicdus Aapor conjointh-, l)ut neglects
other climatic elements, leads to no definite conclusion. Certain climatic
ARGUMENT FROM CLIMATIC CHRONOLOGY SUMMED. 283
conditions, manifesting themselves through temperatm-e and liumidity,
affect hxkes and ghxciers in the same way, while other climatic conditions
affect them in opposite ways.
Reviewing- the entire discussion of climatic analogies, we are forced to
the conclusion that the weight of the analogic argument for the correlation
of lakes and glaciers has been overestimated. The fact remains that the
lake epoch and the ice epoch belong- to the same short division of geologic
time; so does the further fact that each was a peculiar episode, interrupting
a distinct and ver}' different course of events. These two facts establish a
presimiption in favor of their correlation, but this presumption gains only
moderate support from the parallel bipartition of the two sets of phe-
nomena, since the duality of the glacial epoch is not generally accepted;
and it gains no su]:)port, as we have just seen, from the consideration of the
climatic conditions affecting the lakes and glaciers of the Great Basin. The
correlation of the phenomena remains as a working li3-pothesis, but before
it can regain its position as a fully credited theory, it must be sustained by
new arguments. Fortunately, the data for its further discussion have been
developed by tlie geologic researches in the Great Basin, and to these data
we shall presently proceed.
THE EFFECT OF A CHANGE IN SOLAR ENERGY.
The jjresent place, however, is more convenient than any other for the
discussion of a climatic question Avhose answer is of prime im2)ortance in
the interpretation of the geologic dat.t just referred to. The question is
that of tlie influence of a general change of temperature upon the growth
of glaciers. If the radiant energy of the sun were to becf)me greater or
less, how would the glaciers of the earth be affected? Would an increase
in the accession of solar heat, or would a decrease in its accession, cause
the present glaciers to expand and new areas to be glaciated?
It is a familiar fact that the glaciers of the present day are restricted
to regions where the temperature is low. They are more immerous and of
greater size in polar regions, and there oidy do they reach the ocean; in
temperate and tropical climates they occur only^ on high mountains, and
their lower limit varies with the altitude, being highest at the equator and
lowest at the poles. These facts of distriljution have occasioned the preva-
284 LAKE BONNEVILLE.
lent (tpiiiiou that cold is the ])riiuary condition of g'laciation, and that the
climate of the glacial epoch or ejjochs was a cold climate. If it were believed
by all, as it is by some, that Pleistocene glaciation was produced by a va-
riation in solar radiation, the majority would conceive that variation as a
diminution. N(;vertheless, there are not wanting iiivestigators who enter-
tain the opposite view; and so long as these include men of such weight as
Frankland,' Tyudall,- GrolV King,* Whitney,^ and Becker," the majority
should at least refrain from dogmatic assertion. I am therefore not content,
as one of that majority, to let the sul)ject pass with a mere expression of
opinion.
Generally speaking, the vapor tension of the atmosphere is greatest at
sea level, and it decreases rapidly upward. If the air did not circulate,
but remained stationary, the elastic force of the aqueous vapor would cause
it to be diffused ujiward, and the product of evaporation from the ocean
surface would be continuously added and diffused until there was complete
saturation throughout. The theoretic static condition of the atmo.sphere
with reference to moisture is one of saturation. The actual condition of
imperfect saturation is caused by the vertical movements of the air. These,
in accordance with well known laws, produce precipitation, and it results
that the vapor tension of the air at every level is, generally speaking, con-
siderably below the tension of saturation. Strachey, and afterward Ilann,
by studying the records of numerous observations at different altitudes and
in diffei'ent rescions, have deduced the g'eneral law of vertical distribution
of moisture.^ It is, that the relative humidity of the air is not a function
' Oa the physical cause of the Glacial Epoch, By E. Fraukland. Philosophical Magazine, vol.
27, 1864, p. 321.
^Tbe Foruis of Water, by John Tyiidall, p. 151. Also, Heat considered as a Mode of Motion,
Ch.ap. VI.
•'Climate and Time in their Geological Relations, By James CroU, New York, 1875, p. 79.
■•The Geological Exploration of the Fortieth Parallel, by Clarence King, vol. 1, p. 52.'i.
'The climatic changes of later geological times, by J. D. Whitney, Mem. Mus. Comp., Zool.
vol. 7, No. 2, pp. 20.^-6, ;i21, '.iSS.
<■ Temperature and glaciation, by G. F. Becker, in American Journal of Science, 3d series, vol. 2G,
pp. 167-175; also vol. 27, pp. 473-476.
'Ou the distribution of aqueous vapor in the upper parts of the atmosphere, by Lieut. Col.
Richard Strachey, F. R. S., Proceedings Royal Society of Loudon, vol. II, 1860, p. 182.
Ou the diminution of aqueous vapor with increiisiug altitude in the atmosphere, by Dr. Julius
Hann, Zoitschrift Oest. Met. Gesell., lrJ74, vol. 11, p. 193. (Cited from translation by Cleveland Abbe
in Smithsonian Report for 1877, p. 376.)
Strachey notes that the conclusion was originally reached by Ur. Joseph Hooker, but Hooker's
inforeuce was based ouly upon observations in the Himalayas.
EFFECT OF GENERAL TEMPERATURE CHANGE. 285
of altitude, or, in other words, that for each altitude the vapor tension bears
the same relation to the tension of satui-ation. It is not to be supposed that
this law is ordinai'ily illustrated by the condition of a local atmospheric
column at a given instant; it is exemplified only through the comparison of
the means of large bodies of observations.
Notwithstanding the empiric nature of this law, it is possible to extend
its application somewhat beyond the existing order of things; for it is evi-
dent that under the influence of atmospheric circulation the humidity of
each isothermal and isoliygral stratum of the atmosphere is determined by
the humidify of the stratum beneath it, the humidity of the lowest of all
being determined by the rate of evaporation from the surface of the ocean.
A universal rise in the temperature of tlie atmosphere, unless it was suffi-
cient to materially accelerate the circulation, would have the effect merely
of raising all the isothermal strata and inserting a warmer stratum at the
base of the series. This, by virtue of its higher temperature, would accel-
erate the oceanic evaporation, and thus be enabled to maintain the relative
humidity required by Strachey's law. Tliis conclusion implies that rates
of oceanic evaporation are proportional to the saturation tensions of the air
at the surface of the ocean, so long as the relative humidity is unchanged;
a proposition readily deducible from the accepted law of evaporation.^
In stating the above propositions, it has not been possible to incorporate
continuously the qualification that they are of the most general character
and ignore the extreme variability in time and place wliich characterizes
both temperature and humidity. Despite this qualification, they appear to
' In an article "On the depeniloiice of water evaporation ou tlio temperature of the water anil
the movement of the air", published in the Repertoriiim fur Meteorologie, St. Petersburg, l-^TT, Article
3, p. 6, Stelliug deduces and applies the follovvinj; formula:
» = A(S — 8) -t-B (S — ?)"•>
in which v is the rate of evaporation, S is the saturation vapor tension corresponding to the tempera-
ture of the evaporating water, .v is tlie vapor tension of the air in contact with the water, ?« is the
velocity of the wind, and A anil 15 are constants. Siuce for the present purpose wo may ignore local
variations, we are enabled to simplify the formula by regarding the contiguous air and water as of
the same temperature, and by regarding the wind as coustaut. With this modification the formula
becomes:
» = Constant X (S' — s), or r = Constant x S' (1 — ^,)^
in which S' is the saturation tension of the air. The fraction |^ expresses the relative humidity, and
since this is by postulate constant, we have t', the rate of evaporation, a simple function of S', the sat-
uration tension of the air.
286 LAKE BONNEVILLE.
me to warrant the following corollary. If a general rise should take place
in terrestrial temi)erature, affecting all local temperatures alike, tlie local
moisture condition would be similarly affected. The local capacity for
moistun^ hcing everywhere greater, the local vapor tension would likewise
be greater, but the relative humidity for each locality would remain the
same. The evaporation not only from the ocean, but from lakes and sur-
faces of ice and snow, would be increased in the ratio of the increase in the
local saturation tension.
The increase in capacit}' for moisture for every unit of temi)erature
change is not in precisely the same ratio at all temperatures, being somcwluit
less for high temperatures. But the difference is so small that no material
error is introduced by saying that the evaporation of moisture from the
entire earth's surface is proportional to the saturation tension corresponding
to the mean temperature of the surface. Since the total evaporation is
precisely equal to the total precipitation, it follows that the latter likcAvise
is a simi)le function of the saturation tension, and the distribution of temper-
ature remaining the same, the local precipitation follows the same hnv of
change as the local evaporation.
Up to this point it has been assumed that the movements of the atmos-
phere in direction and velocity are unaffected by a general change of tem-
perature, and it now remains to consider the validity (^f this assumption.
The rate of evaporation is known to depend in part on the velocity of the
wind, and the rate of precipitation is known to depend in part upon the
amount and intensity of cyclonic action. We will give first consideration
to wind velocity.
The mean temperature of the surface of the earth, reckone(l from the
freezing point of water, is about + IG° (J. The absolute zero of tempera-
ture is considered to he — 273° C, so that the mean absolute temperature
of the earth's surface may be taken as 289°. If the constitution of the
atmosphere were fixed, it is prol^able that there would be required, to in-
crease of temperature of the earth's surface by 10°, an augmentation of
solar heat amounting to ^ or i of the present amount. In fiict, however, the
constitution of the atmosphere is variable ; at higher temperatures it con-
tains a larger amount of aqueous vapor, and its power to absorb and retain
GLACIATION AND SOLAR EADIATION, 287
heat and thus acquire temperature is reciprocally augmeuted l)y aqueous
vapor. For this reason, tlie ratio of solar radiation to lie added tor 1(P rise
of temperature is something less than ^^. l^eing unable to evaluate this
qualification, we shall make use of the fraction unchanged, with the under-
standing' that it is too larofe. Owiuff to the difference in attitude of tlie
various portions of the earth with refei^enee to the sun, the distribution of
solar energy is unequal, and hence arise the ])rincij)al contrasts of tempera-
ture on the earth's surface. These contrasts cause the atmospheric circula-
tion, by means of which a partial equalization of temperature is eff"ected.
The difference between the solar energy received in high latitudes and that
received in low, or the diff"erential solar energy, is the force manifested in
the winds, and its work is the friction of the circulation. The differential
energy is directly proportional to the total solar energy. The law of aerial
friction is not known, but it is commonly assumed to be a function of the
square of the velocity. If this assumption is coi'rect, then the square of the
velocity of circulation varies as the solar energy, and an increment of ^ in
solar energy will produce an increment of i in velocity. Considerations
connected with the conveyance of heat through the circulation of moisture
show that this estimate is somewhat too large, but as we are unable to give
them a quantitative expression, we pass them by. The formula for rate of
evaporation given by Stelling (see note to page 285) makes that rate a
direct function of the velocity of the wind, but in such way that on the
average the rate varies only about ^ as rapidly as the wind. The ratio of
wind acceleration for 10° rise in the mean temperature of the earth's surface
being less than j.'^, the ratio by which evaporation would be accelerated
through wind velocity by the same rise of temperature is less than j^^. The
smallness of this ratio assures us that the acceleration of the wind may
safely be disregarded in a discussion of such general changes of tempera-
- ture as may reasonably be postulated to account for Pleistocene glaciation.
The conditions under which cyclones are generated are comparatively
obscure; but in the ultimate analysis they are necessarily referred to differ-
ential temperatures created by the sun. It is probable, therefore, that, like
the general winds, they would be affected little by a general rise in the
temperature of the atmosphere.
288 LAKE BONNEVILLE.
It is to be noted that an increase in wind velocity, by increasing
evaporation, would raise the relative humidity, and thereby increase the
preci})itation. An increase in cyclonism, on the other hand, by increasing
precipitation, would decrease the relative humidity, and thereby increase
evaporation. The conjoint effect upon evaporation and precipitation is
therefore cumulative, while the effect on relative humidity is, at least par-
tially, compensatory.
Finding no ground for important ([ualificatron on account of varpng
intensity of atmosjjheric circulation, we return to the original deductions as
substantially accurate: First, a general rise of terrestrial temperature will
increase evaporation, general and local, in the ratio of the saturation ten-
sions corresponding to the initial and final temperatures. Second, it will
increase precipitation, general and local, in the same ratio.
We are now prepared to discuss the immediate conditions of glacier
growth, and will first consider a region in which the temperature never
rises above the freezing point. In such a region, the only factors affecting
the accumulation of snow are precipitation and evaporation. If the former
is in excess, there is an accumulation, and its amount is measured by the
difference of the two factors. Since each of these factors follows the same
law in regard to temperature, that law applies also to their arithmetical dif-
ference; and a change in the mean annual temperature will affect the snow
accumulation in the same ratio that it affects the saturation vapor tension
of the air. If the temperature rises so as to exceed the centigrade zero
during a portion of the year, the annual cvcle of climate becomes immedi-
ately divided into two portions, which it will l)e convenient to call winter
and sunnner. Snow accumulation, then, has a higher rate, by reason of the
higher temperature, but tliis higlicr rate is restricted to a sliorter period.
With progressive advance of amuinl mean tcmperatiu'i', the rate of snow
accumulation is progressively increased, while its period is progressively
shortened, until finally, when the annual temperature c3-cle falls entirelv
above the freezing ])oint, snow accunudation ceases altogether.
As soon as the temperatm-e cycle includes sunnner, a thii-d factor is
inti'oduced — melting. Snow is melted in part by contact with warm air, in
part by heat radiation from the lower part of the atmosjjhere, in part by
GLACIATION AND SOLAR RADIATION.
289
direct insolation, in part by the heat liberated in the formation of dew, and
in part by warm rain. Tlie rate of melting is thns a complex function of
the temperature of the air, the humidity of the air, the clearness of the sky,
and the temperature of the rain. But these four factors are so i-elated
among- themselves that a single one, the temperature of the air, may fairly
Ije regarded as the measure of the rate of melting. The temperatui-e of
the lower air is itself conditioned by the clearness of the sky, the humidity
of the air is, broadly speaking, conditioned by its temperature, and the
temperature of the rain is conditioned by that of the air. The total annual
loss by melting depends likewise on the length of summer, and for present
purposes its measure may be assumed to be the product of the length of
summer into the mean temperature of summer, exjjressed in centigrade
degrees.
For the purpose of bringing together the conclusions of the j^i'eceding
paragraphs, we shall now resort to a gi-apliic method. By the aid of a
few temporary postulates, the law of snowfall and the law of snow-melting
may each be given the form of a curve, and the relation of these curves
will exhibit the law of n^vd accumulation. In Fig. 35 the line X X' is a
scale of temperatures, each point rep-
resenting a mean annual temperature
of a particular district. The tempera"
^lu-es are reckoned in centigrade de
grees, and at every tenth degree a
vertical is erected. Vertical distances
represent rates of snow accumulation
and of snow melting. For the con-
struction of the curves, three postu-
lates were made. First, that whatever
the mean temperature of the locality,
its temperature range or the difference between the mean temperatures of
its coldest and warmest months is 20° C. Second, that its annual curve of
temperature change is of the usual type for cold regions. Third, that the
rate of precipitation is uniform throughout the year. The line C D E is
the curve of snow accumulation. For all temperatures below —10° its
MON I 19
— AO —to O +IO'
Fig. 35. — Fir.st Diagram of Glaciation Theory.
Hori-
zontal distances repl'esent Mean Annual Tenii)erature
in Centigrade deffi-ee.s. Tlie ordinate^ oi C D E are
rates of Snowfall (leas evaporation). Tbo ordinates of
A B are rates of Melting.
290 LAKE BONNEVILLE.
ordinates .ire proportioned to the corresponding saturation tensions. For
each point between — IC and +10'^, the ordinate represents the product
of the corresponding saturation tension ])y tlie k^ngth of winter, expressed
as a fraction of the year. The hue A B is the curve of mehing. Each of
its ordinates represents, for the corresponding mean annual temperature, the
product of the lengtli of sunruner into the mean temperature of summer.
To the left of A it coincides with the axis A X. Each of these curves rep-
resents a system of ratios, and the unit in each system is arbitrarily assumed.
Any other assiimption of relative magnitude might have been made ^^•ith
equal propriety, but such assumption would not affect the essential charac-
ters of the curves.
Since each ordinate of the curve C D E represents a rate of snow
accumulation, as affected by precipitation and evaporation, wliile each
ordinate of the curve A B represents a rate of melting, the diti'erential
ordinate included between corresponding points of the two curves (to the
left of their intersection) represents that portion of the winter's snow which
survives the summer's melting. It represents the net accumulation. Its
maximum value is at A, corresponding to the mean annual temperature of
— 10°. With progressive fall of temperature it diminislies, at first rapidly
and afterward slowly. With progressive rise of temperature it diminishes,
at first slowly and afterward rapidly to the point of intersection, I.
We may now, before drawing final conclusions, examine our postulates,
and inquire what errors they introduce. In addition to tliose stated above
there are several implied postulates Avhich are worth}' of consideration.
First, it is assumed that the annual temperature range, or, more pre-
cisely, the range of the monthly means of temperature, is 20° C. This is
not far from the average temperature range in existhig glacier regions, but
there are some localities where the range is somewhat less, and others where
it is much greater. The assumption of a different range would produce in
the diagram a pair of curves diftering in proportions but identical in type.
Secondly, it is ])Ostulated that a clinnge in the general tenq)erature is
not accompanied by a change in tlic local annual temperature range, or, in
other words, that the temperature i-ange is constant, 'i'he 2«'ecise nature of
errors introduced by this postulate is not easily seen, but considerations
EXAMINATION OF POSTULATES. 291
analogous to those to which attention was called in discussing' the variations
of wind velocity suggest that a rise in general temperature would produce
a slight expansion of local temperature range. The corresponding corrective
modification of the curves would fall entirely to the right of the ordinate
A D, and would be unimportant.
Thirdly, it is postulated that the local annual curve of temperature is
of the type usually observed in cold regions. If observation afforded us
information in regard to the temperature cycles of n('\(' districts, their type
would be the one to employ in the construction of our curves; but there is
no reason to believe that the error incurred by our ignorance of this point
is considerable.
Fourthly, it is j)ostulated that the curve derived from the monthly means
fully represents the temperature oscillations of the year. This is manifestly
untrue, for not only is there a diurnal oscillation, often comparable in range
to the annual, but there are also non-periodic oscillations of considerable
magnitude. It is a matter of ordinary experience that a melting of snow
often takes place during the warm jiortion of a day whose mean tempera-
ture is below the freezing point, and that precipitation sometimes takes the
fonn of snow during the cold part of a day whose mean temperature is above
the freezing point; and that snows may fall in tlie midst of summer and
thaws occur in the midst of winter. Thus the actual temperature range in
any individual year is greater than the range obtained by the method of
monthly means. It is impossible to make satisfactory allowance for this in
the construction of f)ur cur^'es, for the reason that the importance of the
diurnal and non-})eriodic oscillations varies greatly with latitude and with
distance from the ocean. The curves as drawn represent sufficiently well
the relations of snow accumulation and melting at maritime stations, but
not at interior stations. The general nature of the modifications necessary
to adapt them to interior stations is easily indicated. With the mean annual
temperature at 0° C, the ratios of precipitation and melting are tmaffected
by the neglected oscillations. With the mean annual temperature at or
near — 10°, the ratio of precipitation is diminished and that of melting
increased. With the mean annual temperature at + 10°, the ratio of pre-
cipitation is increased and that of melting diminished. The application of
292 LA.KE BONXEVILLE,
these corrections to the diaf^'ram would lower the curve C D E in the im-
mediate vicinity of D, smoothing- out the angle at that point, would leave it
unchanged where it intersects the ordinate of 0°, and would carry the point
E farther to the right. It would raise the curve A B at A, and lower it at
B, leaving the central })ortion unchanged. The j)oint A, or the intersection
with the horizontal axis, woidd be thrown to the left.
Fifthly, in the construction of the cm-ves no allowance was made for
evaporation during summer. The curve 1) E includes onh' winter evapora-
tion, the curve A B only summer melting. The rate of evaporation for
snow and ice has its maximum at 0°, its law changing at that point. In
the general law for aqueous evaporation, the rate of evaporation is a func-
tion of the difference between the saturation tension corresponding to the
temperature of the evaporated substance and the actital vapor tension of
the evaporating air. Since snow and ice can not rise in temperature above
0'^, thev can only be evaporated when the aqueous tension of the air in
contact with them is less than the saturation tension ior 0°. If it rises above
that, moisture is deposited on the ice as dew, instead of being abstracted
from it. In all but very exceptional cases the range of summer tempera-
tures under which nevd can evaporate is small — from 0° to 5° or 6°. The
effect of the evaporation is to retard the wasting of the ice, for the energy
consumed by it is deducted from that available for melting, and a unit of
solar heat can melt seven times as nnich ice as it can evaporate.^ The cor-
rection, if applied to the curve of melting, would slightly increase its upward
concavity.
Sixthly, the winter evaporation embodied with the winter precipitation
in the curve D E is tacitly assumed to have a rate corresponding to the
mean annual teini)erature; its rate is reallv less, being a function of the
mean winter temperature. Au error is thus manifestlv introduced, and this
error is greatest for the amuial tem})eratures corresponding to short winters.
A corresponding correction of the diagram would raise the line D E by
amounts increasing ])rogTessively from D to E.
'The conditioriH deteriiiinin<; tlie evaporation of ice .iiid the formation of <le\v on glaciers are
clearly set forth liy Heim, who cites experinieut.xl verifications by Diifonr and Forel. See " Handlimh
der Gletscherkiiudi'," by Dr. Albrecht Heini, p. 2yS-'241, and Bull. Soc. vaudoije deg sc. uat. 1871, pp.
4 9-410.
CORRECTIOK FOR POSTULATES.
293
Seventhly and finally, it is postulated that the precipitation is uniform
throughout the year. Perhaps no better postulate could he made if" we
wished to express the general fact for the entire earth or for a hemisphere;
l)ut oxu- attention is really restricted to a peculiar class of localities, namely
those in which the climatic conditions are somewhat favorable to the forma-
tion of nevds. It is evident that the massing of precipitation in winter is
a favorable condition, and we might with propriety assign to our typical
locality a precipitation curve including a winter maximum and a sunnner
minimum. Such a precipitation curve would increase all the ordinates of
the line D E of the diagram, except those at D and at E.
Of these postulates, only the fourth and seventh materially aflPect the
problem under consideration. The diagram (Fig. 35) represents sufficiently
well the neve conditions at stations of maritime climate where the precipi-
tation is equally distributed through the seasons, but it fails to represent
them for stations of continental climate, and for stations at wdiich the annual
curve of precipitation has a decided maximum. It is desirable to give
graphic expression to these classes of stations also, but it is unnecessary to
consider them separately, since the modifications which they occasion affect
different portions of the diagram.
Both types are combined in Fig. 36,
the computations for which assumed
a mean diurnal temperature range of
10'^, and a midwinter precipitation
twice as great as that of midsummer.
The vertical distances between
corresponding points of the lines GDI
and X A I, as before stated, represent
annual additions to the n^ve at a
particular locality, each individual
vertical corresponding to a particular mean annual temperature of the place.
The position of the maximum vertical indicates the temperature at which
the annual neve increment reaches its maximum. The position of the
intersection of tlie two lines indicates the limit to ndvi formation, or the
annual temperature above which niv6 does not gather.
+/0- ' X
Fii::. 36. — Second Diagram of Glaciutiuu Theory. Ilori-
zontul distaucua ii'preseut uiuau auiiual tmuperaturo iu
Centigrade dejireea. The orilinatea o{ C V E are rates of
Snowfall (less evaporation). The oidinatea of A 11 are
rates of Melting.
294 LAKE BONNEVILLE.
We may repeat, too, that as the ordiiiates of tlie two curves express
ratios only, the amplitude given to the curves of the diagram is a mere
matter of convenience. Their relative amplitude, on the other hand, is a
matter of importance, to which some attentii)n nuist be given before the
curves can be pro])erly interpreted. Assuming that the amplitude, with
reference to the axis, of the curve of melting, A B, is fixed, the amplitude
of the curve of snowfall, C D E, varies with the precipitation as controlled
by local conditions. For localities of great precipitation its amplitude is
great, and the point of intersection, I, falls to the right of its mean position.
For localities of less precipitation the amplitude is less, and the point of
intersection falls farther to the left. For localities whose precipitation does
not exceed the evaporation, the amplitude becomes negative, the curve falls
below the axis, and the expression for the ndvd increment has no positive
value. Now, for the localities of existing n^vc^s the highest mean annual
temperature is approximately 0°, and it may be assumed without material
error that for the most favorable localities the amplitude of the snowfall
curve is such as to bring its point of intersection with the melting curve on
the ordinate corresponding to 0°. The snowfall curve of the diagram there-
fore has an amplitude near the maximum, and represents a locality of great
preci})itation (as compared to other localities at the same temperature) and
highly favorable to the accumulation of n^v^.
In different localities the highest annual temperature consistent with
nt^ve accumulation may be as low as — 10° or as high as 0°, or, more accu-
rately (giving heed to the first postulate), the range of the limit is from the
climate whose mean midsummer temperature is 0° to the climate whose
mean annual temperature is 0°. Tlie maximum neve increment in the case
represented by the diagram is at — 9°. With the greatest admissible ami)li-
tude of the snowf^xll curve it Avould be at about — 8°. With a very .small
positive amplitude it would be a few degrees below — 1()°. It does not
vary far in either direction from — 10°, or (admitting the tpialitication of
the first postulate) frt)m the animal temperature corresponduig to a mid-
summer temperature of 0°.
For each locality there is a definite temperature limit above which
n6v6 can not accumulate. Starting from this limit, the maximum rate of
GLACIATION AND GENERAL TEMPERATURE. 295
nevd increment is reached by a fall of temperature ainounting- to something
less than half the annual range for the locality. With continued lowering
of temperature, there is progressive diminution in the amount of snow
annually added; but, within the range of temperature the consideration of
which is demanded bv our practical problems, there is no uidicatidn (if an
inferior temperature limit to the accumulation of snow.
In applying these principles of ndvd increment to the correlation of
glacier expansion with its appropriate temperature change, it is convenient
to consider two cases. First, let us conceive a mountain slope all parts of
which have the same type of annual snowfall curve. The actual snowfall
at each level depends upon the temperature corresponding to that altitude.
A certain temperature marks the lower limit- of nijve increment, and there-
fore the lower limit of ndvd. From this limit upward to the summit, the
whole surface receives an annual increment of snow, which is not dissipated
in place but is eventually converted into ice and flows downward to be
melted below the niv6 limit. The maximum increment to the nivi occurs
some thousands of feet above the limit — according to local conditions it may
be 1,000 feet or 10,000 feet. - A volume of ice equivalent to the total annual
n^v^ increment passes each year from the n^vt^ zone to the zone of melting,
and the distance to which the ice advances is a function likewise of the
annual supply aiforded by the ndv^. Assume, now, that the general tem-
perature rises and is continued at a higher rate until the forces once more
reach an equilibrium. With the rise of the isothermal planes the neve limit
rises, and likewise all elements of the nivii sheet. The zone of nevd accu-
mulation loses a strip at its upper margin and the total amount of the ndv^
increment becomes less. The annual tlow of ice from the zone of ntv6 to
the zone of melting is correspondingly less, and being sooner melted, it
maintains a narrower zone of melting. Thus in every way a rise of tem-
perature diminishes the glaciated area.
Consider now a spot which by its topographic configuration is rendered
favorable to the accumulation of nevd, although surrounded by a region
unfavorable to such accumulation. Assume that the temperature is at iirst
high, and then falls with secular slowness. As soon as it passes the local
limit, the foi-mation of n^ve begins. With still lower temperatures, the
296 LAKE BONNEVILLE.
annual increment becomes greater, up to a certain maximum, and afterward
becomes less. As soon as the temperature permits the accuirmlation of
neve, motion ensues, and a stream of ice flows from the locality. The .stream
is at first small, rapid, and short: rapid, because ice moves most freely wlien
near its melting ],)oint ; small, because it is rapid; and .short, because little
descent is necessary to bring it into the zone of melting. As the tempera-
ture falls, the motion is retarded by diminishing plasticity, and to maintain
the annual discharge a greater cross-section is necessary. The annual dis-
charge, being equal to the annual ndvd increment, is at first inci-eased and
afterward diminished. Its increase conspires with the impairment of plas-
ticity to enlarge the cross-section; its final decrease at very low tempera-
tures tends in the opposite direction, and may ultimately overpower the
effect of diminishing plasticity and diminish the cross-section ; but the tem-
pera tiu'e of maximum cross-section must lie far below the temperature of
maximum ndve increment. Within the limits of our practical problem, the
depth and breadth of the glacier increase with fall of temperature;' and its
length increases at the same time, because the conditions of melting are less
and less favorable the lower the temperature. Conversely, a rise of tem-
perature diminishes at once the glaciated area and the depth of the ice.
A moment's reflection will show that into these two cases all actual
cases are resolvable; and as their indication is identical, we conclude in
general that a universal rise of terrestrial temperature, such as would be
produced by an increased supply of solar heat, would everywhere diminish
the magnitvide of neves and glaciers.
It has been previously pointed out that an increase of glaciation in the
Sierra and the Wasatch by means of a general elevation of the district
'Snow is ordinarily welded into ice by the freezing of interstitial water; bntatlow tenipeiatunH
there is no interstitial water, and the welding can be accomplished only by great prcssnre. In regions
where the temperature never rises to 0\ a great depth of snow is necessary to the con.solidation of iho
lower Layers. From the nature of the case, this dry welding can not be observed in natnre, but its
actuality has been demoustnated in the laboratory by the expcrirntnts of Mr. E. Ilnngerford (Amer.
Jour. Science, vol. 23, 18H2, p. 434). If our existing glaciers include any which arise in this way,
tho.se of the Antarctic regions are probably of this class. In small di.stiicts of great cold, such as the
tops of high mountains, the dry snow is drifted freely by the wind and finds its nay to lower levels
instead of accumulating in great mass whore it falls.
It is conceivable that an extremly cold climate would demand for the consolidation of its snow
a greater pressure than would ever be realized by its accumulation, but such a hypothetical case is
beyond the limits of the Pleistocene problem.
FRESn-WATER SHELLS. 297
would be accompanied by a lowering of the temperature of the district;
and that a similar lowering of the temperature would accompany an in-
crease of glaciation by the encroachment of the Pacific on the California
coast, by the lowering of the temperature of the Pacific, or by a small
change in the direction of the great air current. Adding now that a lower-
ing of temperature through the lessening of solar heat would increase the
glaciation, we may continue the discussion of the Pleistocene lakes with the
assurance that if they were contemporaneous with the ancient glaciers of
the Sierra Nevada, they occurred during epochs of relative cold.
THE EVIDENCE FROM MOLLUSCAN LIFE.
The hydrographic basins of Lake Bonneville and Lake Lahontan have
the same latitude, lie at sensibly the same altitude, and are in general
characterized by identical physical conditions. They are moreover con-
tiguous, and separated by no barrier. There is thus every reason to group
them together as a single homogeneous fauna! district, and it will be advan-
tageous so to regard them in discussing the climatic interpretation of the
vestiges they contain of Pleistocene life. The Bonneville fauna has been
enumerated in an earlier chapter. The Lahontan ftxuna is described by
Russell in his monograph.^ Each is meager, but taken together they afford
bases for climatic inference in two biologic divisions, the division of fresh-
water mollusks and the division of vertebrates.
The fresh-water mollusks were collected as opportunity offered by
Russell's parties and my own, and specimens were sent to Call for examina-
tion. His preliminary results were of such interest that it was determined
to afford him an opportunity to study the fossils in the field and to collect
their living representatives in the same district. He accordingly visited
Utah and Nevada in the summer of 1883 and spent two months in gather-
ing the recent and Pleistocene shells. The combined collections were after-
ward studied by him and became the subject of an essay on the Pleistocene
and recent mollusca of the Great Basin, which was published as a Bulletin
of the Survey.^ The statements ^\hich follow are partly based on this
publication.
' Geological History of Lake Lahontan, pp. 23S-249.
^On the Quaternary and Recent mollusca of the Great Basin. By R. Ellsworth Call. Bull.
U. S. Geol. Survey No. 11, 1884, pp. 13-07.
298
LAKE BONNEVILLE,
As appears from the following table, 18 species have been obtained
from the Bonneville strata and 23 from the Lahontan. Eight of these are
identical, making the whole number of species from the entire district 33.
The number of recent species known in the same district is 36, and 2G of
these are specifically identical with the Pleistocene forms. The entire
known fauna of the district, recent and Pleistocene, comprises 43 species.
Table XI. — Fresh-water Shells in the BonnevilU-Lahontan Area.
R = Recent. B = Bonneville. L = Lahontan.
Unionklai. ..
CorbiculidsB
Limnseida) .
Margaritana niargaritil'era, Liiiii.
Aiiodonta mittalliana, Lea
Sphuirium dentatuni, Hald
striatinum, Lam
Pisidiuiii coiiipressum, Prime
abditiim, Hald
ultramontauuin, Prime .
Helisoma corpulentiis, Say
ammon, Gould
trivolvis, Say
suborenatus, Carp
Gyraulus parvus, Say
vermicularis, Gould
Menotiis opercularis, Gould
Limnophysa palustris, Miill
sumassi, Baird
liumilis, Say
bulimoides, Lea
bounevillensis, Call
desid iosa, Say
caperata, Say
Limniea stagnalis, Linn
Radix aiiipla, Migli ..
Pbysa gyrina, Say
bumerosa, Gould
ampullacea, Gould
beterostropba; Say
elliptica, Lea
lordi, Baird
Pompliolyx effusa, Lea
Carinifex uowberryi, Lea
Aucylus newberryi, Lea
sp. iudet
R
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
L
SHELLS OF BONNEVILLE AND LAHONTAN.
299
Tablk XI. — Fresh-waler Shells in ike Bonneville- Lahontan zlrea— Continued.
R = Recunt. B = Bonneville. L = Lahontan.
R
R
15
B
B
B
B
B
L
L
L
ValvatidiP
Pomatiopsidie
Fluminicola fusca, HaUl
Pyrgula nevadensis, Steams
R
R
R
R
R
Bythiuella biuneyi, Tryoii
Valvatai virens, Tryon .. .... . .
sinccra. Sav ... ..-.-
Poniatiopsis 1 ustrica, Sav ... ......
Considering that the search which has brought to light these 43 species
has been far from exhaustive, alike in the existing waters and in the Pleis-
tocene strata, it is somewhat remarkable that five-sixths of the fossil fonns
are known also in the recent waters of the district; and we are permitted,
if indeed we are not- compelled, to regard the Pleistocene and recent faunas
as actually identical.^ The differences between the known faunas are there-
fore referable to accidents of discovery, and can not be given a climatic
interpretation. If however we restrict attention to the 26 identical species
and compare the fossil with the living representatives, we find a varietal
difference of very striking character. The fossil shells are smaller than
the li\-ing shells of the same species. This fact was discovered by Mr. Call
during his preliminary examination of the fossils and Avas afterward verified
by an elaborate series of measurements. Not all of the 26 species were
collected in sufficient numbers to afford a good determination of the average
size, but enough of them were well represented to give assurance of the
generality of the law of difterence.
'This inference .-uliiiits of a niatliem.atical expression. \i the streams and the .strata contain not
only the same nnmber of 8i)ecii'.s bnt the same species, and if eacli of these is equally discoverable, then
the most probable nnmber of identities or coincidences between the known living species and the
known fossils is expre.ssed by the product of the number of living species known into the number of
fossil species known, divided by the total number of species in the entire fauna. We do not know this
total, but it surely exceeds 4;i; considering how very small a portion of the entire field has been
searched, there can bo no exaggeration in estimating it at GO. The mathematical formula then gives
— — — = 20 as the most probable number of identical forms in the fossil and recent collections. In
bu
point of fact, not all species are equally discoverable. Some are relatively conspicuous and others
relatively ubiquitous, and these would be more likely to occur in both collections aud thus increase
the number of identical forms. The number of coincidences actually observed, 20, is therefore in
apparent harmony with the number theoretically deduced.
300 LAKE BONNEVILLE.
Depauperation and coid.-To accouiit for tliis difFereiicG ill size, several hypoth-
eses were suggested, but only two appeared worthy of discussion, ;ind to
these Mr. Call directed his attention. Tlie first hypothesis is tliat oi cold,
the second that of salinity. It was already known that the life of each
molluscan species is conditioned by a certain range of temperature and
by a certain range of salinity, and it was naturally inferred that a lowering
of temperature insufficient to cause extinction iniglit induce depauperation,
and that a similar effect might be produced l)v the presence in the ancient
lake waters of a small percentage of saline matter. For the pur})ose of
testing these inferences, comparative measurements were made of shells now
living in waters of various temperatures, and also of shells now living in
waters differing in salinity — all specimens being obtained from the Bonne-
ville-Lahontan district.
Church Lake, near Salt Lake City, Utah, has an altitude of about 4,300
feet; Little Gull Lake, in the Mono Basin, at the eastern l)ase of the SieiTa
Nevada, lies three degrees farther south, and has an altitude of about 7,700
feet. The temperature of the second locality is not known as a matter of
observation, but a comparison of topogTa])hic relations, and especially of
the terrestrial floras, leads to the belief that there is about as much differ-
ence as that indicated by the altitudes, the climate at Little Gull Lake
being 8 or 10 degrees (F.) colder. From these two lakes the same species,
Pluisa ampullacea, was obtained in the same month, and comparative meas-
urements were afterward made of series of adult shells. The ratio of size
(linear) was found to be 100 (Church Lake) : 86 (Little Gull Lake).
Honey Lake, California, and Warm Spring Lake, Utah, lie at nearly
the same altitude and latitude. Their temperatures are not known l)y
observation, but as Warm Spring Lake, being of small area, lias for its
principal tributary a large spring of water at 128° F, it is higldy prol)al)le
that its molluscan life is conditioned by the higher temperature. Specimens
of Limuoplujsa italiistris were collected from both lakes and afterward meas-
ured, the averages showing a ratio of 100:88 iu favor of tlie specimens
from the Avarm lake.
These two illustrations support tlie hypothesis that within the climatic
range of the Great Basin a low tt'inperature of lake water is less favorable
to the growth of gasteropods than a high tem2)erature.
CLIMATIC TESTIMONY OF FOSSIL SHELLS. 301
Depauperation and Saiinity.-In Seeking fov natui'al examplos illustrating the
effect of salinity, there was not the same success in the elimination of coin-
cident differences of station. Some of tlie brackish lakes of the Lahontan
district contain living shells, liut these are not aA'ailable for comparison,
because the same species have not also been discovered in the fresh waters
of the district. Recourse was therefore had to brackish si)rings, and the
shells inhabiting these were compared, one species with the denizens of a
fresh-water lake and another with the denizens of fresh-water ponds. The
brackish springs affording the shells rise from the Bonneville marls at the
eastern base of the Promontory range in Utah, and are not thermal. Their
waters were not analyzed, and their salinity was tested only by taste. It
was estimated to be less than 0.5 j^er cent. Specimens of Limuophijsa
palustris from these spring's were compared with other specimens from
Honey Lake, and found to be only seven-eighths as large, the precise ratio
being 87 : 100. Specimens of Ph//sn gi/rina were compared with other speci-
mens from fresh ponds near Salt Lake City, and found to have a linear ratio
of 82 : 100. It appears, then, that salinity is quite as competent as cold to
determine the depauperation of fresh-water gasteropods.
We are thus led to inquii'e whether there is any independent evidence
in regard to the freshness or salinity of the waters of the Pleistocene lakes.
In the case of Lake Lahontan the presumption is strongly in favor of
salinity, for the lake has no outlet, and though it may jiossibl}' on more
than one occasion have buried its saline matter under playa deposits and
thus freshened its water, we cannot say, with reference to any of the col-
lected shells, that they belong to any such fresh-water epoch. The testi-
mony afforded Ijy the depauperation of the Lahontan shells is therefore not
available in the climatic problem. The case of Lake Bonneville is different,
for during its second expansion it freshened its water by (tverflow, and the
sediment deposited durhig the second rise is clearly differentiated. We
cannot indeed demarcate the })ortions of this bed which Ijelong respectively
to the epoch of rising water, to the epoch of outflow, and to the epoch of
desiccation; but we know from the phenomena of the shore-lines that the
rise of the water was slow, that the discharge was long sustained, and that
the final subsidence was rapid down to the level of the Stansbury shore-
302
LAKE BONNEVILLE.
line. We are thus enalilcd to assert with much confidence that the upper
layers of the White Marl between the levels of the Provo and Stansl)ury
shore-lines were deposited while the lake was freshened by outflow. And
finding- that shells gathered from those layers are small in size, we accept
their depauperation as evidence of a colder climate. The sulijoiued table
shows measurements of 25 adult shells collected from these layers near the
town of Kelton, and gives comparative measurements of IS individuals
found living in Utah Lake, the largest body of fresh water within the
Bonneville area. The ratio of linear dimensions is approximately 3 : 4, the
recent shells being the larger. It is noteworthy that while each series
exhibits considerable range in size, only two or three of the living shells
are as small as the largest of the fossils.
Table XII. Meaauremcnts of Fluininicola fusea.
Living in Utah Lake.
Fossil in Upper
Bonneville.
Length.
Breadth.
Length.
Breadth.
mm.
mm.
mm.
mm.
12.50
8.10
9.94
6.62
12.00
7.80
9.50
6.40
11.90
8.20
9.10
5.50
11.72
7.14
9.00
5.56
11.50
8.00
8.50
5.56
11.30
7.64
H.44
5.60
11.00
7.70
8.36
5.70
10.80
8.00
8.34
5.22
10.50
0.70
8.30
0.10
10.50
6.52
8.30
5.54
10.50
6.40
H.20
5.32
10.24
fi. .'•.0
8. 10
5.08
10. 22
0.90
8.10
5.50
10.10
7.00
8.08
5.28
10.00
7.24
8.06
5.56
9.70
6.72
8.00
5.34
9.70
6.52
7.96
6.50
9.52
7.00
7.94
5.50
10.76
7. 2;?
7.82
7.80
5.40
6.20
7.72
5.38
7.60
5.00
7.58
5.40
7.46
5. 32
7.24
4.98
8.22
5.50
CLIMATIC TESTIMONY OF FOSSIL BONES. 303
THE EVIDENCE FROM VERTEBRATE LIFE.
The Pleistocene luaiuiiiiils tliiis tar discovered in the Bonneville and
Lahontan Basins are few in number. Proboscidean bones {Elephas or
Mastodon^ were found in the "Intermediate Gravels" of the Lahontan Basin
(equivalent to gravels of the Inter-Bonneville epoch), in the Upper Lahon-
tan beds (equivalent to the White Marl), and in a bog resting on the White
Marl. Bones of a horse (Equus), of an ox, and of a llama, and an obsidian
arrow head, were found in the Upper Lahontan.^ Bones of musk-ox dis-
covered near Salt Lake City, though of doubtful age, are presumptively
Pleistocene.
The list is greatly extended by including the fauna discovered by Mr.
C. H. Sternberg near Christmas Lake, Oregon. The locality was afterward
visited by Mr. Russell, who found the containing formation to be a lacus-
trine deposit surrounded by a shore-line, and otherwise agreeing in its phys-
ical relations with the Bonne^^lle and Lahontan and other Pleistocene beds
of the Great Basin. The horizon of the vertebrate remains is close to the
top of the formation, indicating approximately the same date as that of the
White Marl. Cope has studied the bones biologically, and from him we
learn that the fauna includes the coyote, a beaver, and two species of gopher;
and of extinct mammals, the mammoth, an otter, a giant sloth, two species
of horse, three of llama, and a deer. It includes also the copt, three living
grebes, three living geese and one extinct species, an extinct cormorant,
and an extinct swan.^
In order to ascertain the bearing of these vestiges on the question of
the contemporaneous climate, attention Avill be given to the present climatic
and geographic range of such of the species as yet survive, and also to the
present range of the genera to which extinct species belong.
Man is now cosmopolitan. It is known that in Pleistocene time he
lived near the margins of P]uropean and Ameiican ice sheets, but his con-
temporaneous equatorial raiige is not ascertained. The coyote, Canis la-
trans, ranges southward to the plateau of Mexico and northward to the Sas-
katchewan Plains. Near its northern limit the local annual temperature is
' Russell. Geological History of Lake Lahoutau, pp. 238-9, 246-9.
'Bull. U. S. Survey Terrs., vol. 4, 1878, p. 389.
804 LAKE BONNEVILLE.
about tweuty degrees lower than at Christmas Lake; near its southern limit,
more than twenty degrees liigher.
Tlioniomys talpoidcs, a pocket g02)her, ranges from Kansas to tli(; Assini-
boin River, its range including climates slightly warmer and also from ten
to fifteen degrees cooler than that of Christmas Lake. ThoiiioDujs rlusius,
being known only in its type specimen, has no range. The climate of its
sole known locality, Bridger's Pass, Wyo., is five or ten degrees cooler than
that of Clu-istmas Lake.
The beaver reported is Castor fher, the European species; but as the
distinctness of the American form has been denied, it is possible that no
discrimination is here intended. The European beaver lives in northern
and central Europe; the American ranges from Arizona to the Arctic Circle.
Tlie musk-ox is now restricted to that part of North America lying
north t)f the sixtieth parallel. The most genial climate of its range is far
more severe than that of the Salt Lake Valley, but ma}' perhaps be com-
pared witli tliat of the recesses of the Wasatch and Uinta mountains. Dur-
ing the Pleistocene it abounded on the plains of Siberia as Avell as in Ger-
many, France and England.
The other mammalian species are all extinct, and one only is known
to have climatic significance. The mammoth was characteristic of the
European Pleistocene, and was distinguished from living elephants by its
hairy coat.
The modern otters belong to temperate and sub-arctic faunas, and so
do deer of the genus Cerviis. The llamas are at home in the mountains of
South America, and range southward to Terra del Fuego.
Modern representatives of the horse genus live in tropical and tem})er-
ate climates, l)iit in Plei.stocene times they shared with otters iuid ilccrs thr
boreal climate of England.
Of the climate suited to the fossil sloth, Mijlodoit sodaVis, we have no
better evidence than is afforded by his association with this fauna.
The coot, the grebes, and the geese all range far to the north and to
the south of the Christmas Lake localitv. The coot ranges from Alaska to
Central America. Podiceps occldentalis is knmvn to i-auge from Slexico to
northern Manitoba, P. californicus from Guatemala to Great Slave Lake,
CLIMATIC TESTIMONY OF FOSSIL BONES. 305
PodUymhus podiceps from South America to British Possessions. Anser
canadensis extends from the Arctic Circle to Mexico, A. albifnms yamhdi
from Aliiskii to Texas, A. nigricans from the Arctic Circle to the peniiisvila
of California.
The extinct swan and cormorant likewise belono; to genera of consid-
erable range. Though Cyynus and (Jraculus occur chiefly in the temperate
zone, they overpass both the tropic and the polar circle.
The avian life manifestly throws no light on the question of climate,
and the same may be said of man, the coyote, the beavei', the otter, the
deer, the horses, the llamas, and the sloth. The presence of the gopher
comports with the idea that the climate of the lacustrine epoch did not differ
widely from the present climate. Tlie mammoth favors the view that the
climate was cooler. The musk-ox speaks more decidedly of cold, but his
evidence is doubly indefinite; first, because he may have lived on the adja-
cent high mountains instead of in the Salt Lake Valley; second, because
we do not know whether he lived during a lacustrine or during an inter-
lacustrine e))och.
All told, the evidence from vertebrate life appears to me not merely
inconclusive but valueless. Temperature is one of a complex of factors
constituting climate. Climate is one of a complex of conditions limiting
the distribution of vertebrate species. It is not safe to assume in the case
of an individual species that temperature is tlm important or controlling-
factor and then draw inferences in regard to temperature; only the cumu-
lative testimony- of a ftiuna can yield ti-ustworthy conclusions.
The availaljle biotic evidence is therefore restricted to the testimony
of the fresh-water mollusks, and this, if I understand it aright, ])oints to
the conclusion that the lake epochs were epochs of relative cold. So fur as
it goes, it favors the correlation of ice maxima, witli water maxima.
THE EVIDENCE FROM ENCROACHING MORAINES.
As first announced by Emmons, the glacier that formerly descended
Little Cottonwood Canyon from the Wasatch summits left its moraines
within the area of Lake Bonneville.^ A little farther south, two other
' S. F. Emmous. Geol. Explor. of the 40tli Parallel, vol. 2, ji. 354.
MON I 20
306 LAKE BONNEVILLE.
moraines, Ix'loiiging to the same group of glaciers, lie at about the same
level; but with these exceptions all vestiges of the Pleistocene glaciers of
the basin lie above the Bonneville shore-line.
In the Lahontan Basin there are no similar instances of conriguity,
but sevci-al occur in the Mono Basin, and their ])henomena are l^elieved to
be germane to the ])resent discussion. The Pleistocene histor\' of Mono
Lake is recorded, like that of Great Salt Lake, in a sheet of sediments rising
from tlie water's edge to a. system of encircling shoi-e traces. As deter-
mined l)y Russell, the expanded lake had no outlet," so tliat its oscillations
nuist have been determined purely by climate. The Mono drainage Ijasiu
is one of the many components of the Great Basin, and is contiguous to the
hydrographic basin of Lake Lahontan. Like Lahontan, its water supply
is derived mainly from the Sierra Nevada, which overhangs it on the west-
Analogy suggests that its lake surface rose and fell in response to the same
climatic changes that created and abated Lake Lahontan and Lake Bonne-
ville, and this view is sustained by the evident freshness of its fossil shore-
lines. Li one respect, however, the correlation is incomplete. The Bonne-
ville sediments and the Lahontan are each clearly divisible into two series,
separated by a horizon of unconformity by erosion; but in the Mono Basin
no satisfactory division has been made out. To my mind, this negative
evidence, which may fairly be referred to imperfection of exposure, has less
weight than the climatic analogy, and I am decidedly inclined to regard
the maxinnim flood of the Mono Basin as the ec{uivalent and contemporary
of the maximum ilood in each of the larger basins. I shall therefore dis-
cuss tlie relation of the ancient sliore-lines and sediments to the moraines
at the mouths of tlie Siei'iM canyons as a part of the evidence in regard to
th(^ IJonneville climate. First in onh-r, however, are the phenomena of
till! B<iune\ill(! I^asin.
Wasatch-Bonneville Moraines.-The wcstem fi'out of tile Wasatcli is determined
by a great fault. From the line of this fault an alluvial plain desci'uds
westward to the Jordan River and Gi'eat Salt Lake, wliile eastward springs
a steep face of solid rock, the escarpment of the upthrown orogenic lilock.
' Quaternary History of Mouo Valley, Califoruia, by I. C. Rutisull, Eighth Ann. Kept. U. S. Geol.
.Snrvcy, 1881), p. :iOO.
LITTLE COTTONWOOD CANYON MORAINES. 307
At intervals the rock face is divided by narrow clefts or gateways, whence
streams issue from the interior of the range. Between each pair of adjacent
streams is an acute ridge of rock, whose roof-like cross-pi'ofile marks it as
the product of acpieous sculpture. Tlie end of each is truncated by the
great faidt, and the truncated terminals, standing in line, constitute the
rock face at the margin of the plain. The plain was covered by the water
of the ancient lake, and tlie Bonneville shore-line is scored jiartl}' on tlic!
alluvium and partly <»n the tace of solid rock. Little ( 'ottonwooil Ciuiyon
heads in the liighest part of the range, among peaks with an altitu<le of
12,000 feet, and after a curving coui'su of twelve miles ends at the rock face
in a gateway wliose threshold is slightly lower than the Bonneville shore-
line. The glacier which anciently followed it issued from the gateway, and
at its maximum development encroached upon the plain about one mile,
recording its position at various stages by lateral, frontal, and terminal
moraines. Within the throat of the canyon, scattered erratics are the only
debris, ])ut immediately outside are massive lateral moraines. At the mouth
of the canyon its walls are of gray quartzite, which in weathering assumes
a dark brown color, but in the heart of the range they are of white granite,
and the morainal debris at the margin of the ])l;iiu is nearly all granitic.
This contrasts strongly with the dark (puirtzite, and enables tlie observer
to trace out the distribution of the erratics from a single commanding posi-
tion. The lateral moraine at the south is of typical forni — an acute ridge
of granite bowlders. Where it joins the mountain, its crest stands 340 feet
above the flood plain of tlie creek; but it falls away rapidly, and at a mile
it has reached the level of tlie plain, beneath which it sinks. Before disap-
pearing, it divides into four or tlve members, all of which curve toward the
axis of the glacier in such manner as to indicate that they were the lateral
portions of successive frontal moraines. Tlie northern or right-hand lateral
moraine is of a very different type, being broad and flat-topped, and rising-
only about 100 feet above the adjacent flood-plain of the creek. Its surface
exhibits fewer bowlders than does the left moraine; and a fresh section at
one point betrays an obscure horizontal arrangement of its material. Scat-
tered bowlders of granite are to be seen on the adjacent wall of quartzite
for more than 200 feet above it, and these extend northward along the
308 LAKE BONNEVILLE.
mountain side for half a mile beyond the canyon. Their upper limit
becomes gradually lower as the distance from the canyon increases.
A clearer conception of these relations may be derived by consulting
PL XLII, where the morainal masses are colored blue. Tlicir proper inter-
pretation appears to be, that after the glacier had built two lateral inoriiines
upon the phiin in tlie usual way, it expanded t(»wanl tlie Udrtli, overthrow-
ing and overflowing the moraine on that side and destroying its character-
istic form.
The plain into which the branches of the southern lateral moraine sink
and disappear is alluvial. It not merely surrounds the outsides of the
moraines but occupies the space between them, and extends up the canyon
a half mile or more. At its upper limit in the canyon, the creek channel
excavated from it is shallow, but its depth gradually increases, being 60
feet near the ends of the moraines, and nearly 200 feet at a point two or
three miles beyond. Where the greatest section is exposed, the allm ium
has a depth of 65 feet, consisting of gravel, coarse and fine, with a prepon-
derance of granitic pebbles and occasional passages of sand. Beneath it, is
a greater depth of fine sand, laminated and ripple-marked, and abounding
in mica flakes. This sand is evidently a subaqueous deposit and records
an epoch during which the lake stood higher than the Provo shore-line.
The gravel above it does not exhibit the cross lamination characteristic of
deltas, and must be classed as an alluvial deposit. It marks a time when
the lake stood lower than the Bonneville shore-line, and is prol)ably refera-
ble to the Provo epoch. To establish the validity of this reference, an
attempt was made to trace the alluvimn continuously to tlu; Pro\-o shore-
line, l)ut this was frustrated by a system of recent displacements A\liich
traverse the plain in various directions, giving rise to ti-rraces which can
not in every case be distinguished from the stream terraces with wliic-h they
are associated. After making all allowance for displacements, however,
it is sufticiently evident that when the ancient alluvium was deposited,
the descent of the stream was less ra])id than at present, and this slo^\er
descent is most satisfactorily accounted for by assuming a barrier of lake
water. The alluvium is therefore referred to some epoch of the expanded
lake.
BIG WILLOW CREEK MORAINES. 309
The next canyon to the southward is distinguished from Little Cotton-
wood Canyon by having a steep grade thi'oughout. Instead of beginning
in the recesses of the range, it heads upon the western face and descends
abruptly to the plain. At its lower extremity are moraines equally massive
with those of Little Cottonwood Canyon. They include two lateral moraines
about a mile in length, springing from the angles of the canyon walls, and
iniiting in an excejjtionally heavy terminal. Just within the mouth of the
canyon is a well-defined frontal moraine, and the branching of the laterals
indicates that a second frontal was formed between this and the terminal,
but has been buried by the alluvium accumulated above the terminal. The
outflowing stream. Dry Cottonwood Creek, has indented the terminal, but
cascades in passing it, and has nuich work to perform before it will have
established a uniform grade through it. The base of tlie terminal is in this
case not ])uried l)y alluvium, but the configuration of the neig'hboring plain
suggests that it may once have been partially covered and afterward denuded
by streams. (See PI. XLII, where the creek is erroneou.sly called "Big
Cottonwood".)
Two miles farther south, a similar high-grade canyon, whence issues
Big Willow Creek, is furnished at its mouth with a similar moraine system,
of which the terminal is the most conspicuous element. It stands free upon
the surface, with no evidence of an alluvial or lacustrine covering.
The alluvial plain does not at all points reach the moiuitain side at the
same altitude, but is highest at the mouths of the large canyons. In the
vicinity of the moraines, its highest point is at the mouth of Little Cotton-
wood Canyon, and it is there a few feet above the horizon of the Bonneville
shore-line. Elsewhere the shore-line is scored upon the steep mountain front.
It is to be seen a short distance north of the northern moraine of Little
CottouAvood Canj^on; it appears again between the moraines of Dry Cot-
tonwood and Big Willow Canyons; and it reappears beyond the latter; but
no trace of it was detected upon the moraines themselves. In the case of
the Little Cottonwood moraines, the alluvial cover prevents examination at
the horizon of the shore-line; but the other moraines are fully exposed to
view.
310 LAKE BONNEVILLE.
Before attempting- tlie interpretation of tlusse glacial plienoinena, it
will be well to recite again the lacustrine history \\ itli w hich tlie}- are to he
compared. Lake Bonneville^ was twict; foriiuMl and twice dried away. It
attained its maxinuim size during- its second term, and the records of the
second rising so far mask and obliterate the records of the first, that these
are discovcirable at comparatively few j)oints. The shore-line oljserved in
the vicinity of the moraines, and the alluvial and lacustral deposits ex))osed
on the banks of Little Cottonwood Creek, all licloiig inupiestionably to tlie
second Bonneville epoch, and that e|)och ah me can we hope to compare
with the epoch of the moraines. When the lake reached the horizon of the
Bonneville shore-line, during its second rising-, it found outlet, and its fur-
ther rise was jirevented. The erosion of the barrier was exceedingly rapid
until the water had fallen to the Provo level. The resistance of this lime-
stone held the lake at a constant height for a long- period, and from this
level the w^ater finally receded by desiccation. Had the rim of the basin
been so high as to ])revent outflow, we can not say how far the lake would
have risen before the passage of the climatic maximum permitted it to fall
again. We may be siu-e, however, that the climatic maximum was some-
what later than the epoch of the Bonneville shore-line, (^n the other hand,
the lake area at the Provo stage was only two-thirds as gi'eat as at the
Boinieville, and the peculiar climatic changes that expanded the lake were
fast declining when the water finally fell from the Provo shore-line. The
climate of maximum efficiency for the production of lakes therefore occurred
after the epoch of the highest shore-line and before the close of the epoch of
the Provo shore-line.
If the glaciers had attained their maximum extent either during or
before the epoch of the Bonneville shore-line, their terminal moraines would
have been subject to wave action at that horizon, and scored with shore
marks; but the tw'o terminal moraines wdiich are well exposed to view
exhibit no .shore-lines. If the glaciers had attained their maxinnnn after the
close of the Provo epoch, the Little Cottonwood moraines should rest upon
the alluvium, instead of being partially buried beneath it. It apjiears quite
consistent with the phenomena to suppose that the ei)Och of maximum
glaciation was covered by the longer epoch of the Provo shore-line. The
WASATCH MORAINES AND LAKE BONNEVILLE. 311
j^reater part of the alluvium outside the moraines may have been deposited
while they were in process of formation, the inter-moraiiial portion being
added after the ice had retreated.
We are thus led to assign the same narrow time limits to the epoch of
the climatic maximum tending to produce lakes and to the epoch of the
climatic maxiimmi producing glaciers; and one ftxrther step will lead us to
the conclusion that the two maxima are identical. But before taking that
step, we must examine the evidence from the Mono Basin.
Sierra-Mono Moraines.-Tlie Pleistoccne lilstory of the Mono Basin was syste-
matically investigated by Russell. Oidy a few days were spent by mo in
the valley, and these were devoted chiefly to the features described in the
following paragraphs. In preparing these paragraphs, I have availed myself
of Russell's work whei-ever necessary, but the local descriptions are mostly
at first hand. The reader who cares to pursue further the history of the
valley will find it fully presented in Russell's paper.^
Lake Mono has an altitude of 6,730 feet. When expanded by the
Pleistocene climate, it carved a maximum shore-line 670 feet higher. The
eastern face of the Sierra Nevada is here remarkably abrupt, and the Pleis-
tocene high-water mark runs very near its base. In glacial times the broad
back of the Sierra bore a great field of ndvd, the surface of which ranged
in altitude from 10,000 to 12,000 feet. From this streamed glaciers east
and west, and five of the eastward-flowing entered the Mono basin. One
sto|)ped before reaching the level of the old shore-line, the other four
readied it or passed beyond it. These will be enumerated in order from
north to south, with whatever description is necessary to show the relation
of the observed glacial phenomena to the lacustral.
The Mill Creek glacier emerges from its rocky channel and debouches
upon the plain at the horizon of the old shore-line. Beyond its walls of
rock its dimensions are indicated by lateral moraines, which rapidly con-
verge and at the same time bend northward. They are steep-sided ridges,
studded with large bowlders. They extend less than a mile upon the plain,
and though no terminal moraine is visible, we are assured by their converg-
ence that they represent the full length of the glacier. The old shore-line
'Eighth Ann. Kept., U. S. Geol. Surv., pp. 261-394.
312 LAKE BONNEVILLE.
is distinctly marked not only on tlic ontcr lace of tlie riglit moraine l)ut on
the extremities of both, and for a sliort distances on the inner faces of l)oth.
Its character is tliat of a chtf and terrace, Init the notch is not deeply cut,
and the extremities are iKit slightly truncated.
Seven miles farther south Lee\'ining Creek issues from the mrmntain
fjice .at ahout tlie altitude of the old shore-line. The modern lake is there
close at hand, and the mountain face is steep. Upon the steep slope, the
creek has l)uilt a large alluvial structiu-e which projects a cape more than a
mile into the lake. This mass of alluvium has not the symmetrical form of
an alluvial cone, but descends somewhat unequally and irregularly, being
evidently a comjjound delta, the component parts of which were formed at
different levels of the lake. The glacier following the valley of this creek
had for several miles a uniform width of 1^ miles, and this width was
not diminished at the mouth of the canyon. Like the Mill Creek glacier,
it curved northward at that j)oint, its left margin following the flaring mouth
of the canyon, while its right, as indicated by the surviving lateral moraine,
swung free. One mile ( )f this free moraine is preserved, but no terminal is
to be seen. There are, however, two well marked frontal moraines King
respectively three-quarters of a mile and two miles back fiom the end of
the lateral. The old shore-line is scored on the outside and inside of the
lateral moraine, and appears also on the ojiposite side of the glacial channel
against the face of the mountain. It can be traced only a short distance
uj) the glacier valley, because its features have been i-ecently obliterated
by the creek. The end of the moraine has evidently been cut away by the
waves, but the extent of this removal is unknown. The surviving portion
affords no indication, by size or direction, that the end of the glacier was
close at hand. When the lake stood about 33 feet lower than its highest
shore-line, the creek built a small delta at the mouth of the ghn'ial Aalley,
the front of the delta reaching to the end of the truncated lateral 7noraine.
The head of the delta was at the foot of the lower frontal moraine. Near
its head there is a terrace eight feet higher, which appears to be a fragment
of an earHer built delta that was destroyed during the construction of the
lower one. The creek channel now lies entirely below these delta plains.
MORAINES OF THE MONO BASIN. 313
Tlie next glacier descending to the lake level issued from Bloody Can-
yon, six miles tarthei' south, and at the time of its greatest development
stretched four miles upon the plain. Its position on the plain is marked by
a pair of lateral moraines, which gradiially converge as they descend the
slo].:)e. From lioneath the right member of this pair issue the extremities
(»f two other pairs, marking earlier courses of the same glacier. These
older moraines do not rise so high above the plain as those later formed, and
are less acute in profile. They have evidently been subjected to atmos-
pheric agencies for a relatively long time, and it seems probable not only
that their crests have been worn and rounded, l)ut that their bases have
been buried by the slow accumulation of alluvium. The waves of the
ancient lake barely reached the extremities of these moraines, older and
newer. The Hood plain of the streamlet which issues from between the
newer moraines coalesces at their extremities with the terrace wrought by
the waves, so that we cannot say in this case whether the lake water entered
the valley between the moraines. The moraines end in low sea cliffs, and
there is no terminal, though the convergence of the laterals indicates that
the ice projected a little farther. That a terminal properly belongs to the
system seems to be shown by a series of frontals, deposited at intervals
farther up the ice channel.
The Rush Creek moraine surpassed all the others in size, having a
width of 1§ miles where it entered the })lain. Its lateral moraines stand
free for a distance of three miles, and each one is characterized by several
parallel crests, continuous with corresponding frontals. Three frontals of
some magnitude follow each other in rapid succession near the end of the
laterals. The position of the terminal, or extreme frontal, is not certainly
known. The old shore-line is but faintly traced in this portion of the basin,
where it margined a sliallow bay, l)ut its horizon was determined to fall
near the base of the outermost frontal. A half mile farther down the
slope the plain is interrupted by a few small islands of morainal matter,
unmistakably characterized as such by the presence of gigantic erratic
bowlders. These mark the position of what may be another frontal moraine,
but is probably the terminal moraine.
314 LAKE BONNEVILLE.
Witli one voice these four localities tell us that Mono Lake occupied
its maximum level after the glaciers of the Sierra had retreated from their
most advanced position. But their testimony goes no farther. The nar-
row range of levels connnon to the two niay have been occupied first by
the ice and afterward hy the water, or it may have been occupied l)\ botJi
tog(!ther. We can oidy say tliat the ice was first to retreat.
Combining this result with that afforded by the moraines of the Bonne-
ville Basin, we conclude that the epoch of greatest glaciers fell within the
second period of lake expansion, but did not coincide with the ei)och of
greatest watei'-supply; it occurred somewhat earlier. If the two sets of
phenomena were consequent ujjon the same series of climatic changes, then
the lacustral changes lagged behind the glacial.
That such a lagging admits of plausible explanation may readily be
shown. The ncvd and glaciers of the Mono district occupied a portion of
the catchment basin of the lake. The preci})itation which they accumulated
during their growth was subtracted from the precipitation tributary to the
lake, and the same was afterward returned to the lake when they were
finally iiielted. Their mass of ice may therefore be regarded as a portion
of the water-supply of the lake, arrested in its progress. When the climatic
conditions were favorable for the growth of lake and glaciers, the growth
of the glaciers antagonized and delayed the growth of the lake. When the
climatic conditions favored the wasting of lake and glaciers, the waste of
the glaciers fed the lake and thus antagonized its depletion. The ascend-
ing and descending phases of the lake thus fell behind the corresponding
phases of the glaciers, and the maxima and minima, or turning* points, Avere
correspondingly displaced.
It is to be observed that this explanation is quite distinct from the
theory, alluded to by Whitney,* that the Pleistocene lakes were the secpiel
of the Pleistocene glaciers, being created by their melting. Such a relation
is quantitatively impossible. In the Mono basin, indeed, the mass of snow
and ice upon the mountains may have been equal to the \(ilume of Mater
in the valley, but in the Lahontan and Bonneville basins it was far too
small. King's map of the Pleistocene glaciers of the Bonneville Basin indi-
' The Climatic Changes of Later Geological Times, p. 185.
SIERKA MORAINES AND LAKE MONO. 315
cates a superficial extent of 710 square miles, an area only j^ as large as the
water surface of Lake Bonneville. ( )ne thousand feet is a liberal estimate
of tlie mean depth of the ice, while the mciin dcptli of Lake Bonneville was
about 700 feet. The body of water was therefore about twenty times
larger than the body of ice.
The evidence from the moraines is thus shown to be consistent with
that from the moUuscan fauna, and they jointly confirm the presumption
derived from the recency and exceptional nature of the lakes and glaciers,
that the two phenomena were coordinate and synchronous results of the
same climatic changes. The correlation of the phenomena, originally l)ased
on analogy merely, is thus sustained, and it now stands on a surer founda-
tion.
It fi)llows as a corollary that the glacial period of the Sierra Nevada,
the Wasatch, and other mountains of the western United States was divided
into two ei)ochs separated by an interglacial epoch; and this has not been
independently shown. The bifurcation of the Bloody Canyon moraines
demonstrates a temporary retreat of the glaciers, but that retreat was not
necessarily great. The following explanation of the bifurcation, advanced
by Russell' and McGee^ appears to be fully sustained l)y the phenomena.
After the glacier had constructed on the plain its oldest pair of lateral
moraines, it retreated to a point near the canyon, and there deposited a
heavy frontal moraine. Readvancing, it was opposed by this frontal, and
found a point of least resistance in the left lateral moraine, wliich in each
pair is lower than the right. Overriding that, and finally demolishing it,
it took a new course upon the plain, and this new course was afterward
modified by the same process, the obstructing frontal being near the
extremity of the laterals. At almost any point in the history thus deduced
from the moraines, there might have occurred a great retreat of the glaciers,
involving even their temporary extinction, without the production of any
features we should be able to detect.
■ Eighth Ann. Rept. U. S. Geol. Survey, p. 357.
''Meridional deflection of ice streams, by W. J. McGee, Am. Jour. Sci., 3d Series, vol. 29, p. 386.
316 LAKE BONNEVILLE.
SUMMARY OP CHAPTER.
Tlie Bonneville Basin originated by distortion of the earth's cnist, and
came into existence long before the Bonneville epoch. Little is known of
its earliest climatic and physical conditions, but it was coinpaniti\ely dry
for a long period immediately preceding the formation of the great lake.
During this period, alluvial cones were formed about the bases of all its
greater mountain ranges, and the smaller ranges were wholly or partly
buried by valley deposits. The valley deposits may have been entirely
alluvial, but were probably also partly lacustral, the lakes being oi' small
extent.
There followed two epochs of high water, Avith an interval during
which the basin was nearly or quite empty. The first of these epochs was
at least five times as long as the second. The second scored its water
mark 90 feet higher than the first, and would have encroached still farther
on the basin sides had it not been checked by outflow. During the epoch
of outflow, the discharging current eroded the rim, and thus lowered the
lake 375 feet; and after the outflow had ceased, the Avater fell by desicca-
tion, with one notable interruption, to its present level in Great Salt Lake.
The inter-Bonneville epoch of low water was of greater duration than the
time that has elapsed since the final desiccation.
The final drj-ing of the basin divided it into ten or twelve independent
interior basins. Two of these now contain lakes, the others for the most
part contain playas, or playa lakes wdth beds of salt. The Sevier Basin is
exceptional in that its lake was 30 miles in length when first surveyed, and
has since disappeared, the water of its tributary stream being appropriated
for irrigation.
Since 1845, the date of the first record, the surface of Great Salt Lake
has oscillated through a range of 10 feet, reaching maxinia in IS;').") and
1S73, and minima in 1847-50 and 1861. Since iSTlt there lias l)een little
change. A progressive fall in the future is indicated, not as a matter of
climate, but as a result of the rapidly increasing utilization of tlie tributary
streams for the pin'])oses of agriculture. Tlie changes in level have l)een
associated with changes in area and vohune. The maximum area was
about 25 per cent, gi'eater than tlie mininunn, and the maximum volume
CONCLUSIONS ON CORRELATION OF LAKES AND GLACIERS. 3 1 7
about 75 per cent. The salinity, which is high, has varied inversely with
the volume, and the predicted decrease in volume will lead to tlie preci})ita-
tion of a portion of the mineral contents.
A comparison of the lake's oscillations with the meteorologic record
of the region a])pears to show that the height of the lake in any year is a
cumulative function of tlic jirccipitation during preceding years, 1)ut estab-
lishes no relation between lake oscillations and temperature oscillations.
The modern oscillations of lake surface are exponents of the ii'regular
rhythm of climate due to the interaction of complex conditions otherwise
constant. The great oscillations which alternately created and destroyed
Lake Bonneville are of a different order, and require for their explanation
more permanent changes of conditions. An examination of the topography
of the liasin shows that such diversion of water-courses and other local
geographic changes as may possibly have occurred are inadequate to
account for the rise and fall of the lake. The history of the Bonneville
oscillations is moreover closely paralleled by that of the Lahontan oscilla-
tions, and it is believed that they belong to a series of climatic changes
affecting not only these two basins but the adjacent subdivisions of the
Great Basin. The question whether the lakes are phenomena of the Pleisto-
cene period, their expansion being wrought by the same climatic factors
which enlarged the glaciers, has previously been answered in the affirmative
on the basis of certain analogies. A review of these analogies indicates that
two are valid, while two others are not. The common recency of lakes and
glaciers, as indicated by the freshness of the vestiges, affords a presunq)tion
in favor of their identity in time, and a forther presumption is afforded
by the fact that the lacustral and glacial phenomena each interrLq)ted a
series of events of a different character. The argument from the parallelism
of the lacustral and glacial histories, each being characterized ))y two prin-
cipal maxima, is weakened l)y the fact that tlie liighest autliorities on the
Pleistocene period are not agreed in regard to its l)ipartition. The l)elief
that any climatic cause competent to increase glaciation would likewise
increase lakes appears on analysis to be ill-founded, certain possible com-
binations of conditions being competent to cause simultaneously an increase
in the area of ice and a decrease in the area of water.
318 LAKE BONNEVILLE.
The discarded arguments from analogy are replaced by other argu-
ments of a more direct and satisfactory nature.
A discussion of the conditions controlling the climate of the western
United States sliows that any change competent to increase the glaciers on
on the mountains would lower the temperature of the lake basin.s. An
appeal may therefore be made to the fauna of the lake epoch for infonnatioii
in regard to climate. Hie manunals give no intelligible answer; but the
fresh-water mollusks declare by their dei)au}jeration that the conditions of
life were then less favorable. In the case of Lake Lahontan, and in the
case of the first Lake Bonneville, the unfavorable condition may ])ossibly
have been impurity of water; but the second Lake Bonneville was freshened
by outflow, and the dwarfing of its mollusks is best explained by low tem-
perature.
The moraines of three Pleistocene glaciers descend from the Wasatch
]\Iountains to the level of the Bonneville shoi-e-line; the moraines of four
glaciers descend from the Sierra Nevada to the level of the old shwe-line of
Mono Lake; and the relations of these moraines to the shores of the lakes
and the associated deposits indicate that the maximum stage of the lakes
coincided closely with the epoch of maximum glaciation.
These phenomena sustain the theory that the Pleistocene lakes of
the western United States were coincident Avith the Pleistocene glaciers of
the same district, and were produced by the same climatic changes. It fol-
lows as a corollary that the glacial history of this region was bipartite, two
maxima of glaciation being separated, not by a mere variation in intensity,
but by a cessation of glaciation.
CHAPTER VII.
LAKE noNNEVILLE AND VOLCANIC ERUPTION.
Ill this chapter it is proposed to show the relations, and especially the
chronologic relations, between the volcanic history and the lake history of
the Bonneville Basin. The only species of volcanic rock there erupted
during or near the Bonneville period is basalt, and this appears to have
lieen thrown out alike before, during, and since the lacustral epochs. The
description of the various lava fields will in a general way follow the
inverse order of their formation, but precedence will be given to the more
typical localities.
Of the various volcanic districts of Utah, that which is most interest-
ing in this connection occupies the eastern portion of the Sevier Desert in
the vicinity of the towns of Holden, Fillmore, Corn Creek, Kanosh, and
Deseret. The Pavaiit Range there forms the eastern limit of the desert
plain, and is itself composed of uplifted strata ranging in age from Car-
boniferous to Tertiary. The volcanic buttes and tables, all very small as
compared to the mountain range, rest upon the open plain, at distances
varying from 10 to 30 miles. Nearest to Fillmore is the Ice Spring lava
held, with its cluster of craters. Just south of it are the Tabernacle field
and crater. Still to the southward and 10 miles away are two considerable
buttes, not far from the town of Kaiiosh, and west of these lies a higii
basaltic table several miles in extent. North of the Ice S})riiig field there
is a continuous volcanic tract, some 10 miles in extent, for the most part
coincident with the plain, but including also a large mesa opposite Holden,
and a large tuflP cone, Pavaiit Butte. West of this tract and south of the
town of Deseret lies a basalt table, and farther south stands a tuft" cone,
Dunderberg Butte.
310
320 LAKE BONKEVILLE.
The Ice Spring- craters, the Tabernacle hiva beds, and Pavant liutte were
first visited by the writer in 1872, and an account of them may be found
in the report of the Wheeler Survey.^
ICE SPRING CRATERS AND LAVA FIELD.
I'he lavas of tliis locality are the most recent within the BonneAalle
area, and tlicir phenomena are ty})ical of subaerial eruption.
The craters are grouped closely together, and the manner in which
they overlap each other, as well as their relations to the various lava fldws,
demonstrate that they were formed successively rather than synchronousl}'.
Three only are preserved entire, but frag-ments of nine more were discov-
ered, and it is probable that the denudation of the locality would reveal
beneath the accumulated lava and scoriae the remains of numerous others.
Of the discovered crater rings no two are concentric. Thei'e have been
at least twelve successive eruptions, through as many independent vents,
within a radius of 1500 feet, and none of these eruptions appear to have
been large. It would seem that the subjacent terrane opposes so little
resistance to the upward progress of the lava that a new opening is made
more easily than an old one is reopened after a cessation t)f activity has
permitted congelation in the conduit. The immediately subjacent forma-
tions are in this case probably the White Marl, the Yellow Clay, and other
feebly coherent valley deposits.
The dimensions and general relations of the craters and laxii fields will
be best understood if the reader will examine Pis. XXXV, XXXVII and
XXXVIII in connectioirwith the followhig description. ( hw of the largest
of the scoria hills is the Crescent, a crater fragment showing nearly one-
half of the original circle. It rises 2f)0 feet above its eastern base, and
tlu! entire crater api)ears to have had a diameter of 2200 feet. It is coiii-
po.sed of scoriaceous fragments, in the main loosely aggregated, but in part
bound together by harder layers which appear to have been jjroduced by
sj)lashings of molten lava from the crater. These give it a rude concentric
stratification, in the main inclined outward, parallel with the outer slo])e,
but also inclined inward at a very high angle conformable with the inner
' Surveys West of the 100th Meridian, vol. 3, pp. 136-144.
U S. '3 KC LOGICAL SURVEY
liAJ^E BONNEVILLE PL. XXXV
MAPOF A
VOLCANIC DISTKK T,
Near Filicnore , Utah. .
TopogrcLpKy
BvA.L.Vi%l,ster curd K^. Wheeler .
Geology
By O.K. Gilbert aihrl I. CBu^seU .
Legend
NL A'eaer BcLsaTtif: Lean
ScoT-ux,
PL Brt^a itic Zitva ofU'ovo
Scortti.
(^Hxi-erBasattic Irtva.
age
flUler
Hhvollte
Tuff and •Srona.
L -Letci/strirt-eMrrls cuhd Sands
(h-psurn
(r\jhfifkroiis Clay
Gypsiun S^md
Crdcarfoiis Tufa.
.luliutt hi<-n \ Co.Lth
Drawn bv- 11 Tlmiupson
..=-5- ^'^^~'%\Kr
:Htri.j;iliM&i:,
MITER AND CRESCENT CRATERS. 321
slope. One end of the Crescent is buried beneath a lava crater, the Miter,
the other is cut off by a stream of lava flowing from the same.
The Miter is perhaps the most i-eceut of the craters. Nothing over-
laps it, and it has lost nothing by erosion. Apparently the only change
since its formation has been a cracking away of fragments from its harder
components and the accumulation of these in taluses. Its rim is nearly
circular, with a diameter of 950 feet. Its highest side, on the east, rises
250 feet above its outer base and 275 feet above the central depression.
Its history has involved at least two overflows. After it had reached about
its present size the lava rose within it, breached its north side, and dis-
charged. The discharge was followed by explosive eruption and the
breach was repaired. A final upwelling found escape at the west and
trenched the rim deeply on that side. The northerly sill of discharge is
120 feet above the central depression, the westerly 75 feet. The material
is identical with that of the Crescent, and the perfect preservation of the
cone enables the imagination to picture vividly the manner of its forma-
tion. Its principal constituent is scoriaceous lava in angular fragments.
Over the surface are sprinkled clots of similar scoriaceous material, spongy
within, bulbous Avithout, and coherent to the angiilar fragments beneath
them. These are evidently di'ops spattered from the molten mass below,
and retaining their plasticity up to the moment of striking, so that they
fitted themselves to and adhered to the surfaces against which they fell.
They are volcanic bombs whose aerial flight was too short to pentiit them
to harden.
Between the Miter and the Crescent stands a low cone, resembling the
Miter in form, but only 400 feet in diameter. It is composed almost exclu-
sively of angular scoriae. Six fragments of craters project from beneath
the talus of the Miter at various points, another lies outside the Crescent,
and still another joins the inner face of the Crescent to the small crater just
mentioned. A circular hole, more than 100 feet in diameter and 40 or 50
feet deep, is doubtfully classed as a crater, for it is not clear that matter has
been ejected from it. Its interior exhibits only fragments fallen from its
walls.
MON I 21
322 LAKE BONNEVILLE.
Tlie Terrace crater lies just south of the Miter, and differs from the
others in type. Its walls are for the most part low, and are characterized by a
gentle outward slope. At their culminating- point they are scoriaceous, but
elsewhere they are of relatively compact lava, with a nide stratification, as
though formed by the addition of successive sheets. Its fonnation was evi-
dently attended by very little explosive action, and there is some ground
for believing that its cavity was produced by the refusion of scoriaceous
matter, the product of some earlier eruption. Its outline is iiTegular, with
an extreme length of 1100 feet and a width of 700 feet. At one stage in
its history it was occupied by a molten lake about 14 acres in extent, and
the partial congelation of the surface of this lake left a teiTace at one
margin. Tlie subsequent history of the crater includes the formation of
four narrower terraces at lower levels. The first lowering of the molten
lake appears to have been accomplished by the bi'eaching of the crater wall
at the south, and a consequent outflow. The subsequent lowerings were
caused by the retreat of the lava down the conduit by which it had origi-
nally entered the crater from beneath. This conduit remains open and
can be explored for 25 feet, when progress is stopped by water. It is a
circular tube 12 feet in diameter, and inclined 10 or 15 degrees from the
vertical. The stony arrested drops still pendent from its sides testify by
their small diameter to the high fluidity of the lava. The dejith of the crater
below its general rim is 2G0 feet, below the sill of its last outflow 220 feet,
and below the scoriaceous crag that overlooks it on one side 350 feet.
Three thousand feet to the west of the above craters there is a short
fragment of crater wall, with its concavity turned toward the east. It is
nearly buried by the lava streams flowing from the others, but what remains
in view indicates a diameter of half a mile. It bars the i)rogress of the lava
in that direction and helps to give to the outline of the field its bi-lobed form.
The streams flowing from these craters have formed two confluent
fields, the first extending 3.5 miles northward, with a general breadth of two
miles, the second 3.25 miles westwai-d, with a general breadth of 1..") miles.
Their area is about 12.5 s([uare miles. Their marginal depths will average
about 30 feet, and their mean depth is estimated at 50 feet. The vohnne
of the ejected matei-ial is approximately one-eighth of a cubic mile. The
n.
-J
o
2
H
I
m
s
H
nf y
TEKRAOE CliATEE. 323
greater part of this lava is nearly compact, dark gray in fracture, and black
on the suiiace. The fields are everywhere exceedingly rough, correspond-
ing to the "aa" of the Sandwich Island nomenclature.^ The surface is a
heap of ragged, loose blocks, piled in tumultuous waves whose crests are
20 to 30 feet above their troughs. Near the craters these rugosities of sur-
face disappear, and the compact basalt is covered to an unknown depth by
a spongy layer as light as the lapilli, but more even in texture, and main-
taining the somber hue of the streams. The scorice. of the craters is some-
times gray, but is more commonly red or yellow. At a few points on the
surfaces of the streams are small patches of scoria?, colored like the craters,
and one of these which was examined has a conical form, suggestive of for-
mation in situ by eruption from the body of the stream. It is possible,
however, that it is merely a fragment of a fixed crater that was floated off.
The angle of flow was not measured, but is certainly small. In the
vicinity of the craters the grade is conspicuous to the eye, and the lava
must be tliere one or two hundred feet higher than at the margin of the
field. All of the later streams appear near the craters to flow in channels
depressed fifteen to twenty feet below adjacent surfaces, and yet these
adjacent surfaces resemble very closely the surfaces of the streams. The
explanation ap])ears to be that each of these outpourings varied in volume,
now swelling, now shrinking. When most copious it spread beyond its
channel like an aqueous stream, and deposited, not its sediment, but its
crust. The walls of the channels display a confirmatory stratification.
That the entire history of the lava field is post-Bonneville, admits of
no question. It lies within the area of the lake at so low an altitude that
no point of the craters reaches to the level of the Bonneville shore-line, while
the marginal portions of the stream are below the level of the Provo shore-
line. But the craters show no trace of wave work, and on the surfaces of
the lava streams no lacustrine sediments appear. The lake beds surround
the lava, but neither rise toward it nor rest against it. A local fault, which
is seen in one place to have displaced the Bonneville White Marl, disap-
pears beneath the lava field in such a way as to show that the latter was
subsequently spread.
' H.awaiian Volcanoes, by Capt. C. E. Diitton : Fourth Ann. Rept. U. S. Geol, Survey, p. 95.
324 LAKE BONNEVILLE.
At various points there crop out from beneath the Ice Spring field
margins of an older lava or lavas, of uncertain date. They are distinguished
from the newer by the weathering of their surface, which has partially lost
its original rugosity, and bears patches of soil so as to supjiort a scanty
growth of grass and bushes. At two points these are seen to be displaced
by the fault above referred to, and at one place a bed of lava passes under
an exposure of the White Marl. If all these older lavas have approximately
the same date, they are probably older than the BonncA-ille shore-hne.
While the recency of the Ice Spring volcanoes as compared to the
Provo epoch is sufficiently clear, their absolute antiquity is a matter of
doubt. The state of preservation of the latest ejecta is fairly to be com-
pared Avith that of similar material produced by Vesuvius two or three
centuries ago, but the mineralogic differences between the two lavas and
the climatic contrast between the two localities may determine very different
rates of disintegration. At the Utah locality disintegration has produced
no soil even in crevices. A study of the surface details of the more com-
pact lava gives the impression that they have withstood atmospheric influ-
ences. The scoriae have yielded somewhat; in their original constitution
they consist within of thin septa dividing spheroidal bubbles, and without
of a slightly thicker skin against which the outer phalanx of bubbles are
flattened. From the scoriaceous crusts of streams near their sources this
skin has chiefly disappeared. It is well preserved only on the brinks of
the cinder cones, and not on all of those. After my first visit to the locality,
I exhibited to the American Association for the Advancement of Science a
bomb from the Miter crater, and stated that its skin had been exposed to
the elements since the time of its formation.^ A more careful examination
on the ground has satisfied me that I was wrong. The taluses on its outer
and inner slopes show that the crest of the crater is slowly breaking away,
so that the bombs to be seen near the crest may have been until recently
covered and protected by lapilli.
I discovered no accumulation of fine fragments from the disintegi-a-
tion of scorite. They have been absorbed by the crevices and the surface
remains clean. Indeed the formation of a soil is indefinitely postponed by
' Proc. Am. Assoc. Adv. Sci., vol. 23, 1875, p.art 2, p. :!0.
KECENCT OF ERUPTION. 325
the necessity to first fill the all-pervading crevices of the cinder cones and
the aa. Only on the cindery crusts of streams near the craters has a
beginning been made. This is not apparent on the surface, but when the
rock-froth is broken into, its inner cells are found half filled with an exceed-
ingly fine cream-colored dust — evidently an eolian deposit. A few sage
bushes have discovered this and established themselves. No minerals were
seen in the bubbles or other cavities, but the interior of the flue of the Ter-
race crater is decorated with dendi'itic growths of calcareous matter.
The name of the Ice Spring lava beds is derived from what may be
regarded as a natural ice house, existing in one of the deeper hollows of
the aa. It is in a natural pit among the lava blocks, and so sheltered by
an overhanging ledge that it never receives the direct rays of the sun. At
the time of my visit there was a pool of ice water a few inches broad and
half an inch deep, and at its margin, clinging to the rock, a film of ice a few
inches across. My visit was on September 28, and it is currently reported
that ice can always be found. The conditions of the phenomenon appear
to be: first, the accumulation in the crevices of the shattered rock of cold
water from melting snow; second, protection from solar heating- by means
of a heavy cover conducting heat poorly; third, shelter against winds,
which would bring warmth by convection ; and fourth, evaporation. Simi-
lar phenomena have been described at various places in the Appalachian
Mountains.
PAVANT BUTTE.
Pavant Butte, which stands ten miles north from the Ice Spring lava
field and 17 miles by road from Fillmore, is an acute peak, about 800 feet
high. It is the tallest of all the volcanic hills, and, standing alone upon the
plain, is a conspicuous landmark. Its general fonn is that of a cratered
cone, but the crater is open at the south, and the circling crest has an acute
culmination at the north.
Its material is a volcanic tuff"; that is to say, it consists of light lapilli
cemented into a coherent mass. The vesicles of the lapilli are not filled,
but the fragments are so firmly held together that they are frequently
broken across when the mass is fractured. Scattered through the mass are
occasional bowlders of basalt, some angular, others rounded, and these
326 LAKE BONNEVILLE.
must have reached their position })y ejection from the vent, but nothing
was seen that coukl be called a bomb, and none of the scoria; appear to
have fallen in a plastic condition. All of the scoriaceous matter is frag-
mental, and the fragments rarely exceed an inch in chameter. Considerable
portions of the outer slope have the fineness of coarse sand. The prevail-
ing color is a pale yellow, liut some of the weathered surfaces are gray.
In this respect the butte is strongly contrasted with the cinder cones of the
Ice Spring locality, where deep colors, especially red and reddisli broAvn,
predominate.
It has been pointed out by students of existing volcanoes that lapilli
are cemented into tutf when their deposition takes place in the presence of
water. This commonly happens when they are ejected so as to fall in water,
or when heavy rains, accompanying the eruption, wash them down to neigh-
boring lowlands in the form of volcanic mud. In the present instance the
state of flowing mud was not reached, for they are heaped about the vent
in steeply-inclined layers of original deposition. The associated lake phe-
nomena suggest, and indeed demonstrate, that Lake Bonne\'ille afforded
the moisture necessary for cementation, and that the eruption was subaque-
ous. Tlie Bonneville shore-line is trenchantly drawn about the sides of the
butte at mid-height. The Provo shore-line appears at its base, and the inter-
val is destitute of all trace of wave action. It will be remembered that in
the order of time the Intermediate shore-lines were formed first, then the
Bonneville, and finally the Provo. The presence here of the Boime\nlle
and Provo traces shows that the butte was not built after the epocli »>f the
Bonneville shore-line. The absence of Intermediate shores tells us that it
was completed after their date. A portion of the mole may have been
thrown up in the earlier part of the second lake epoch or at any previous
time, but if so, it was completely buried by the product of the final eruption
at the time of the Bonneville shore-line.
This determination of date de])ends on our knowledge of the shore-
line history derived from other localities, but the same information may be
obtained from data purely local. At numerous points on the north side there
is exhibited an unconformity in the bedding of the tufa, and a study of this
unconformity shows that after the waves liiul notched the profile on tluit
PAVANT BUTTE.
327
side, producing a sea-cliff and a terrace, the renewal of eruption partially
filled the notch, the newer layers dipping at a higher angle than the old.
We thus learn by consistent and cumu-
lative evidence that an eruption took place
here while Lake Bonneville was at its liio'h-
o
est stage, and beneath a body of water 350
feet deep. The resulting cone was built not
only to the surface of the water biit 450 feet
'^ Fig. 37.— IMa^am to illustrate the Alter-
higher. Eruption ceased with the fall of °''«<"' "f voicauic Eruption and Littorai Ero
^ ■*■ aion on Pavaut Butte.
the water and has not been resumed.
Notwithstanding the recency of the cone, its sides are conspicuously
furrowed by erosion, and it is in that respect contrasted with most frag-
mental volcanic cones of the vicinity. Where the lapilli are uncemented,
all rain is swallowed by the interstices, and escapes gradually and quietly
at the base. On Pavant Butte this is prevented by the cement, and the
rain flows down the surface, accomplishing its usual work of erosion. The
sides of the furrows exhibit to some extent the internal structure of the
mass, and show it to be a fine type of its kind. There ai'e no partings
between the layers of tuff, but lines of deposition are plainly to be seen, and
these exhibit on the inner side a dip toward the crater at 35 degrees, and
on the outer face an opposite dijj of from 15 to 25 degrees, the two systems
being joined along the crest by
anticlinal curves. A figure illus-
trating this arrangement is here
reproduced from the Wheeler
report (Fig. 38).
The general distribution of yellow and gi'ay colors indicates that the
yellow is original and the gray a result of weathering. The sections
exposed by recent erosion show the main mass to be yellow, but there are
occasional thin bands of gray, and these are inferred to record the temporary
cessation of eruption. The old sea-cliff against which the newer tuff rests
unconformably does not show the gray color, a fact consonant with our
belief that the latest eruption interrupted rather than followed the destruc-
tive work of the Bonneville waves.
Fig. 38.— Section of Pavant Butte. O=0at8ide of Crater.
/^Inside of Crater. B=Bonneville shore-line.
328
LAKE BONNEVILLE.
•v^-- -
- ^,- /■
iXwr
Fir,. 39.— Section at base of Pavant Bntte, showing Eeninant of
earlier Tuff Cone. The dotted lines indicate theoretic sMiictnre of parts
concealed or removed.
From the northwestern base there jut a number of ragged spurs, con-
sisting, like the main mass, of tuff, but exhibiting dips toward tlic liill instead
of from it. A study of their dips shows that the spurs are remnants of an
older crater rim, on whose ruins the surviving rim was built. The diagram,
Fig. 39, shows by full lines the observed relation of dijjs, and Ij}- dotted
lines the theoretic structure
of the parts concealed or re-
moved. The earlier crater
was somewhat smaller than
the later, and its center was
forther noi-tli. Tlie tuff ex-
hibits, throughout, the gray
color referred to weathering. The date of the structure is uncertain. Its
tuffaceous^ character indicates subaqueous eruption. Its color suggests
prolonged exposure to the atmosphere after the chief work of demolition
was perfonned. It may have been built during the earlier part of the
epoch of the "WHiite Marl, while the oscillating lake Avas beginning the for-
mation of the Intermediate shore-lines, or still earlier in the epoch of the
Yellow Clay.
The surface of the plain for a short distance in all directions from the
cone is composed of debris derived from it. Beyond this southward outcrops
the White Marl, and beneath the White Marl a field of lava. The White
Marl seems to be but two or tln-ee feet thick, and as there appears no reason
why the open plain at this point should not receive the full deposit, it is
inferred that only the upper portion is visible, the lower being beneath the
lava. As the Bonneville and Proro shore-lines are contemporaneous with
the upper portion of the Marl, the question arises whether the lava bed may
not be contemporaneous with the later tuff, and derived from the same vent.
The surface of the lava is as perfectly preserved as that of the Ice Spring
field, but is of an entirely different type, corresponding to tlie pahoehoe of
the Sandwich Islands. It exhibits fine examples of the curved convolutions
' Tufa and tuff, etyinologically the same word, have both been used to designate a calcareous
deposit from solntioii ami alHO a cohcront aggregate of lapilli. Following GiMkie, I have in the.se
pages allotted the two words in .wveralty to the two functions, applying tnfa and tu/aceous to the
deposit from .solntion. ami luff -.mil tuffaceoua to the volcanic product.
ERUPTION BENEATH LAKE BONNEVILLE. 329
or wi-inkles that are so suggestive of coils of rope. At the time of my exam-
iuatiou I was disposed to refer these to the inter-Bonneville dry epoch, for
it appeared to me a priori that a lava stream flowing beneath the water
would part with its heat so rapidly that its smooth sui'face would be shat-
tered into fragments. But I am informed by Captain Button that where
Hawaiian lava streams of the smooth type have entered the sea, their surface
characters have not been affected. The evidence comprised in the thinness
of the White Marl and the perfect preservation of the lava surface beneath
it may therefore be accepted as showing that a lava was here spread under
the water during the second lacustrine epoch ; and the close association of
the field with the Pavant tuff is probable. Its area is undetermined, for it
is overlain not only by the marl, but also in places by a belt of sand dunes.
In a southwesterly direction it is visible at intervals for several miles.
TABERNACLE CRATER AND LAVA FIELD.
The typical phenomena of the Ice Spring and Pavant localities simplify
the interpretation of the Tabernacle eruptions. The Tabernacle field lies
immediately south of the Ice Spring, and is mapped on PL XXXV. It is
approximately circular, with an average diameter of tlu-ee miles and an area
of about seven square miles. The point of issue is not central biit lies near
the southeast margin.
The crater has two rims, an outer and an inner. The outer rim is the
older and is composed chiefly of yellow tuff. It contains also some slag-
like material colored dark red and grey. Its contours, which are in detail
the result of weathering, are smooth, except where broken by slaggy crags.
Its surface is largely composed of discrete lapilli, just beneath which the
tuff may be found in place. Two-thirds of the original annulus is preserved,
the part toward the northwest having been absorbed or buried by later
eruptions. The span of the annulus from crest to crest is 2200 feet, and the
ridge is highest on the east side, where it rises 120 feet above the lava field.
Probably a part of its base is concealed by the lava. Its profile as seen
from the Miter crater (PI. XXXIX) resembles the Mormon Tabernacle at
Salt Lake City, sug'gesting an appropriate name. The internal structure of
the ridge is not well displayed, but an outward dip was observed in the
higher part.
330 LAKE BONNEVILLE.
The inner rim is characterized by a great abundance of scoriaceous
matter that evidently reached its position while still pasty and adhesive. It
is not greatly inflated, and its general habit is rather slaggy than scoria-
ceous. The rim is exceedingly uneven, and abounds in rough pinnacles.
Comparing these features with those of Pavant and the Ice S[)ring
craters, we infer with confidence that water was present in the crater during
the greater part of the formation of the outer rim and was absent dm'ing
the formation of the inner rim.
When compact hand specimens of the Tabernacle and Ice Spring lavas
are compared, little difference is seen, but their streams differ widely in
habit. The Tabernacle field, though by no means smooth, is far less rugged
than the Ice Spring. Some of the surface is broken into blocks, which are
so far displaced that they are not easily traversed on horseback ; but the
greater part is comparatively even, and exhibits the ropy structure charac-
teristic of pahoehoe. A conspicuous character of the streams was the con-
gelation of their upper portions and the subsequent escape of the liquid
matter beneath. This is shown in a few places by the preservation of tubu-
lar caves, and more frequently by depressed areas, where the lava crust has
manifestly settled down as its support was withdrawn. The constituent
streams of the field are partially separable, and the latest may be traced to
the inner rim of the crater.
At its outer margin the lava field terminates in most directions in a
cliff — not such a cliff as results from the undercutting' of a lava bed resting
on softer material, but a cliff of original formation contemporaneous with
the upper surface. At a point on the eastern side it was measured and
found to have a height of 65 feet.
On the face of this cliff, near the top, is a ])and of calcareous tufii
adhering to the Ijasalt, and above it there was detected at some points a
terrace of wave erosion. These are features of the Provo shore-line. The
crater rims Ijear no trace of wave work, and this negative evidence is
reinforced by the absence of all lacustrine deposits from the crater, from
the general surface of the field, and from the sunken areas and caves. The
inner rim and tlie field were never sul>merged; the outer may possibly have
been covered at the epoch of the Bonneville shore, but not at that of the
Intermediate shores.
THE TABEENACLE. 331
Lying just above the Provo level, and yet showing no trace of sub-
mergence, the lava field must have been formed after the tall of the water
from the Bonneville level to the Provo. Bearing the Provo shore mark, it
must have been spread before the close of the Provo epoch. It therefore
originated during the Provo epoch. The inner rim of the crater has the
same date. The outer rim is older than the inner and younger than the
Intermediate shores; it belongs to the Bonneville shore epoch or to the
earlier part of the Provo epoch. The presence in it of some slaggy matter
suggests irregularity in the supply of water and indicates the later date.
The most probable history is as follows: When the Pleistocene lake fell to
the Provo level, it had a depth of from fifty to seventy-five feet over the
present site of these craters and lava fields, and there it remained for many
centm'ies. An eruption occurred beneath its surface. At fii'st, or at least
during an early stage, the eruption was explosive, its violence, possibly
stimulated by the water, being so great that the circle of maximum deposit
was more than a thousand feet from the vent. Eventually the growing
rampart shut out the water, the explosions becaine less violent, and the
ejecta became pasty. Quiet eruption followed, developing a low, black
island, which received a wave record before the final desiccation. The
closing phase of eruption was explosive.
The geologic date of this lava field is so well determined that special
interest attaches to the degree of freshness of its surface. Decay has pro-
gressed far enough to obliterate the finer convolutions and somewhat obscure
the coarser — two to six inches across. Probably salient parts have yielded
an inch to atmospheric waste. The minor depressions contain an inch or
two of soil, and small cracks are filled. Large cracks remain open. Judged
by its color, the soil is less the product of local disintegration than of eolian
deposition. The principal vegetation is the common sage of the country.
In the caves the eolian deposit, reinforced by the di'oppings of bats and
probably other animals, has a depth of one or two feet.
The ground just north of the Tabernacle field is traversed by a fault,
with a throw of fifteen or twenty feet to the west. It divides the lava, also,
and was traced with diminishing throw half way to the crater. In the
opposite direction it disappears at the edge of the Ice Spring field, being
overplaced by that eru2:)tion.
332 LAKE BONNEVILLE.
At the side of the fauh is a k)w hill of scoriae, against and around
which the Tabernacle lava flowed. It is a vestige, ill preserved, of some
long anterior bnt dateless eruption. Another vestige, equally vague as to
time, appears in an inclined fragment of a basalt sheet, brought up l)y a
fault at the south margin of the Tabernacle field. This fault is overplaced
by the Tabernacle lava.
PLEISTOCENE WINDS.
The circular wall of a crater often grows more rapidly on one side
than another. This must sometimes be occasioned by the obliquity of the
flue, but observers have generally refen-ed it to the deflection of flying
fragments by the wind. If a group of extinct craters are oriented in the
same way, it seems legitimate to infer the prevailing dhection of the wind
at the time of their formation. In the Fillmore district there is practical
harmony of orientation. The Crescent, the Miter, and the smaller crater
between them have their highest walls at the east. That of the Terrace
crater is at the northeast. The outer rim of the Tabernacle culminates
on the east side, the inner rim on the north. The apex of Pavaiit Butte
stands north of the crater. The entire range of the seven is from north to
east, and the indication is that winds from the south, southwest, and west
prevailed. There are no meteorologic stations competent to tell us whence
the winds blow at the present time, but the prevailing air movement is
recorded by nature in a satisfactory manner. In the vicinity of George's
Ranch, at the south end of the eastern lobe of the Sevier Desert, the Provo
shore-line consists of a series of massive bay bars, composed largely of sand.
These are the source of a broad train of dunes which traverse the desert,
and which demonstrate by their northeasterly course the prevalence of
southwesterly winds. The phenomena consist with the theory that the gen-
eral air cun-ents of this region during the Pleistocene were similar in du-ec-
tion to those of the present time.
FUMAROLE BUTTE AND LAVA FIELD.
The most important locality remaining to be described is at the north-
ern edge of the Sevier Desert, close to the head of the Old River Bed. A
basaltic mesa five miles across in either direction is half divided by a valley
FUMAROLE BDTTE. 333
opening to the northeast. (See PI. XXXI, near bottom.) At its head this
valley is a mile wide, and is floored by red scoriae. In it stands a rough
tower about 160 feet high with a truncated and obscurely crateriform sum-
mit. The predominant colors of the tower are red and gray, and its material
ranges from firm scoriae to compact basalt. These are roughly bedded,
and exhibit a centi-ipetal dip at a high angle. The inten-elations of these
featm-es are easily understood, at least in a general Avay. The tower, Fu-
marole Butte, marks the position of the volcanic vent. About this vent
scoriae were piled (as restored in the diagram) in an annular mole, and
from it escaped the lava of the surrounding mesa. The last phase of
erujition was non-explosive, and compact rock was fonned in the flue.
Subsequent erosion carried away much of the scoriaceous rim, but left the
resistant core and the equally resistant lava field.
c .: e^—
Fig. 40.— Theoretic section of Fumarole Butte. The Cinder Cone is restored by dotted lines.
Before visiting this butte I had listened with incredulous interest to
the statement that smoke or steam Avas sometimes seen to rise from it, but
personal observation subsequently removed all doubt. About the outer
edge of the summit are thirty or forty crevices from which wann, moist air
gently flows. The permanence of the phenomenon is attested by the ver-
dure lining the openings — a deep green moss glistening with moisture and
vividly contrasting alike with the somber rocks and the sparse, ashen vege-
tation without. In diff"erent openings I found the temperatures 62°, 70°,
72°, and 73.5° Fahr., all above the atmospheric mean for the locality, which
is approximately 55°. At the time of observation the outer air had a tem-
peratui-e of 30°, and was dry. A little mist formed over some of the open-
ings, but was reevaporated within a few feet. On days that are moist, cool
and still, a conspicuous cloud must arise. It can hardly be doubted that this
thermal manifestation testifies to a residuum of volcanic heat in the old flue.
A group of hot springs at the southeastern base of the mesa may have
the same significance. Their temperatures range from 110° to 178° Fahr.
334 LAKE BONNEVILLE.
Just north of the mesa is a basaltic hill whose apex overlooks the mesa
and has about the height of the butte. This hill is terraced l)y wave action,
exhibiting especially the Bonneville and Provo shores. Tlie Bonneville
terrace appears also about thirty feet above the base of the butte, and a
single point of the mesa was high enough to receive it. . The I'elation of
these shore benches to the valley about the butte shows clearly that the
excavation of the valley was antecedent and was subaerial. The littoral
excavation was trivial in comparison.
The wet-weather di-ainage of the mesa crosses its liounding cliff at
numerous points, and at each of these a narrow, notch-like valley has been
eroded from the basalt. These notches were cut before the Bonneville
epoch, and during that epoch were partly filled by lake deposits. Subse-
quent erosion has not wholly removed these deposits, and the remnants
show that both Yellow Clay and White Marl were present.
These facts demonstrate that not only the volcanic eruption but the
principal erosion of the volcanic formations took place in Tertiary time.
The surface of the mesa has lost all details of its original configuration.
One can not say whether the flowing lava assumed the rough or the smooth
type. It is far from smooth, but its unevenness apparently depends on ine-
quality of disintegration and erosion. The rock is superficially red from
decomposition, and is generally bare of soil, the slopes of surface sufficing
for the rapid removal of disintegrated material. The margins of the table
on the east and south (where alone they were examined) are cliffs by sap-
ping— that is to say, blocks of rock have fallen away in consequence of the
yielding of a softer substratum. Probably the lava was spread on the plain
before the first establishment of drainage on the line of the Old River Bed.
The carving of that channel lowered the base level of erosion for the i-egion
and induced the general degradation of the plain, so that the field of obdu-
rate basalt became a hill of circumdenudatiou. The greater share of this
process also must be referred to the Tertiary.
The most impressive phenomenon of the locality is the secular persist-
ence of the volcanic heat. At the time of eruption the rocks adjacent to
the conduit or conduits became heated, and the lava remaining in dikes and
chimneys added to the store of heat. Since that time conduction has steadily
U S.OEOLOOrOAL SUFA'EY
layj: bci'Inkvjll:-: fl xli
Juliu» Itirn ft Co.Iiih
Dt-nMn bj- C ThoippBon
ANCIENT CRATER STILL WARM.
335
carried this lieat in all directions, and the convection of snbterranean water
has helped to discharge it to tlie atmosphere, and yet enough remains to
sustain a fumarole ten centigrade degrees warmer than the air. The period
of heat dissipation includes the whole of the Pleistocene period and an
antecedent period of erosion probably of equal length.
OTHER LOCALITIES OF BASALT.
The remaining basaltic masses of the lake area, so far as they were
inspected, do not declare their age by visible phenomena of superposition,
])ut tlie majority can be referred with probability to the Tertiary from a
comparison of their condition of preservation with that of the Tabernacle
field oil the one hand and the Fumarole on the other. This statement
applies to all localities mapped in PI. XLI north of the fortietli parallel
excepting that on Bear River. It applies also to two localities at the west
edge of the Sevier body of the lake, to two near Preuss Bay, to two which
trench on Escalante Bay, to the buttes near Corn Creek (southwest of Fill-
moi'e) and a large table west of them, and to a table lying west of Pavant
Butte and south of the town of Deseret.
Fig. 41— Duuckrburg Butte.
3:!6 LAKE BONNEVILLE.
Between this last-named table and the north end of the Beaver Creek
range stands Dunderberg Butte, the remnant of what may have been
a large cone of scorioe. Its lapilli are coherent, Init have not the yellow
color of the tuff cones. Their mass is traversed by dikes and .sheets of
vesicular liasalt. Some of the basalt vesicles contain calcite and zeolitic
minerals. The top is flat, except where dikes project, having been trun-
cated by the waves at the Provo epoch. The date of eruption can be
judged only from the progress of demolition. It was probably Tertiary,
but may have been inter-Bonneville.
Equally in doubt are a basaltic table north of Pavant Butte and another
south of it and extending nearly to the Ice Spring field.
PLEISTOCENE ERUPTIONS ELSEWHERE.
The same criteria of discrimination may be a})plied with equal pro-
priety outside the lake area, so far as the conditions of rock decay are sim-
ilar. Carefully applied, they would serve to classify the greater number of
basaltic eruptions of the Arid Region as severally Tertiary or Pleistocene.
While engaged in general geologic exploration, I have seen in Utah, Idaho,
Nevada, California, Aiizona and New Mexico about two hundred fields of
lava, judged by their color and habit to be basaltic, and as many as tlu-ee
hundred and fifty cones of basaltic scoria?. My attention was usually not
called to their state of preservation, but the data contained in note books
and memory nevertheless afford a basis for judgment, and I have attempted
a classification, with the following result: Of the streams and fields, 15
per cent, are judged to be Pleistocene; of the cones, 60 per cent.; the
remainder are regarded as Tertiary. Of the eruptions thus classed as
Pleistocene a certain number admit of no question, and these are enumer-
ated in the following paragraph.
On the Markaguut Plateau in southern Utah, close to its western edge,
are three or more lava fields of the rougher type, all fresher in apjDearance
than the Tabernacle field, and ^vith them are ten or twelve cinder cones,
red and black. It is said that Panguitch Lake, a few miles towai-d tlie
northeast, owes its existence to the danaming of its valley by a lava stream
nearly as fresh. On the face of the cliff which bounds the Pownsagunt
PLEISTOCENE ERUPTIONS. 337
Plateau on the south, a cinder cone marks the position of a vent from which
a black stream has flowed down the slope toward the valley of Kanab
Creek. This stream has weathered somewhat more than has the Tabernacle
lava, but recency is indicated by the small amount of subsequent erosion in
a country whose whole configuration indicates rapid degradation. In the
heart of the Uinkaret Mountains of northern Arizona, surrounded by scores
of basaltic streams and craters, the majority of which are probably Ter-
tiary, there is one field of intense blackness rivaling the Ice Spring field in
freshness. South of the Grand Canyon of the Colorado there is a similar
forest of cratered cones about the base of San Francisco Mountain, and as
one surveys them from that peak, his eye is arrested by a lava field at the
east on which vegetation has not yet encroached, and by several craters
near it of exceptional jJerfection. On the source of the San Jose in New
Mexico a stream of lava preserves the wrinkles of viscous flow, and its
siu'face has scarcely yielded to the corrasion of a brooklet that crosses it.
At the southwestern base of the Zuili Plateau, near El Moro, is " a long-,
broad lava stream, comparable in age with the Tabernacle field. In, south-
eastern California, on the grand alluvial cones of the eastern front of the
High Sierra there are a dozen bright red and black cinder cones marking
vents whence basalt has descended toward Owen's River. Farther north,
in the same structural meridian, a small basaltic mass overlies one of the
glacial moraines of Mono Valley.
RHYOLITE. '
Besides basalt, the only important volcanic rock of the Bonneville
area is rhyolite. It stands next also in point of recency, Ijut is far older
than Lake Bonneville. So far as observation extended, its most recent
example is a body lying just east of Coyote Spring, at the south end of the
Sevier Desert. This had an original depth of three hundred feet or more,
and an extent in each direction of several miles; but it has been so dis-
sected by erosion along its lines of drainage that its original configuration
is suggested rather than shown. Its system of valleys has a general depth
of at least two hundred feet, and these are so related to the Bonneville
shore-line as to show their earlier formation.
MON I 22
338 LAKE BONNEVILLE.
Just east of the Tabernacle lava field is a liill of <,n-ey rhyolite one or
two hundred feet high. It is a worn remnant, with nothing in its a.spect to
aid conjecture as to its original extent. Its Ijase is concealed by the lake
beds, and its sides show terracing by the waves of Provo and Intermediate
times. Lying to the leeward of a gy^isum playa, it has acqviired a white
mantle of gypseous sand dunes, whence it is called "White Mountain" (see
page 223 and PI. XXXY).
A portion of the Dug way range, on the south margin of the Great
Salt Lake Desert, is of rhyolite and rhyolitic tuff. It is of such antiquity
that the original shapes due to eruption have been replaced by those of
atmospheric sculpture. From its gorges, as from other mountain gorges,
there are spread great fans of alluvium, and across these completed fans
are traced the shore-lines of Bonneville.
SUMMARY AND CONCLUSIONS.
The extravasation of rhyolite in the immediate vicinity of Lake Bonne-
ville was long anterior to the epoch of the lake. The same may be said
of the' earlier extravasations of basalt, but the period of basaltic erujjtion
includes the period of lake extension. In the Fillmore district basalt was
extruded at various times during the epoch of the White Marl (later Pleis-
tocene), and from one vent there were eruptions after the final desiccation
(post-glacial).
The states of preservation of lava beds of various determined epochs
afford a rude scale for the chronologic classification of lava beds not other-
wise correlated, and warrant the conclusion that in Utah, Nevada, New
Mexico, Arizona, and California the majority of basalt flows are Tertiary;
a small minority are Pleistocene, and of these a few are post-glacial. The
post-glacial eruptions are found in each of the indicated States and Terri-
tories except Nevada, and belong to eight distinct volcanic districts.
Although human history fails to give satisfactory record of the occur-
rence of any of these eruptions, their antiquity, as measiu'ed in years,
can not be great, and an application of the general law of ])robabilities leads
us to look forward to a resumption of volcanic activity. The subteiranean
reaction of which basaltic extravasation is the consequence has continued
VOLCANIC EPOCH NOT CLOSED. 339
in the broad region not only tlirough the Pleistocene but through a much
longer period of preceding time. The intermittence of eruption doe-s not
argue discontinuity of the subterranean process, for, whatever that process
may be, it involves the production of an unstable equilibrium that is con-
verted to stable equilibi-ium only by eruption, and such conversion is
always rhythmic. The abrupt cessation of a process so widely spread and
so long sustained is highly improbable, and its gradual cessation would
naturally include not only growing infrequency of eruption l^ut the suc-
cessive extinction of eruption districts. The number of post-glacial erup-
tions and the number of districts among which these were distributed alike
assure us that the end is not yet.
Their distribution in time and space indicates that the volcanoes and
the lakes have been genetically independent. The Fumarole volcano broke
out during an epoch of aridity, long before the first expansion of the lake;
the Pavant and the Tabernacle were built on sublacustrine foundations;
the Ice Spring volcanoes continued the series after the water had subsided.
Outside the basin there was a parallel volcanic history, and though the
volcanic districts are irregularly disposed, one can not say that they are
either more or less abundant in the vicinity of the site of the lake.
CHAPTER VIII.
LAKE BONNEVILLE AND DIASTROPIIISM.
The displacements of the earth's crust which produce mountain ridges
are called orogenic. For the broader displacements causing continents and
plateaus, ocean beds and continental basins, our language affords no term
of equal convenience. Having occasion to contrast the phenomena of the
narrower geographic waves with those of the broader swells, I shall take
the liberty to apply to the broader movements the adjective epeirogenic,
founding the term on the Greek word tJTreipo?, a continent. The process
of mountain formation is orogeny, the process of continent formation is
epeirogeng, and the two collectively are diastrophism.^ It may be that
orogenic and epeirogenic forces and processes are one, but so long at least
as both are unknown it is convenient to consider them separately.
The mountain ranges so thickly set in the Bonneville district, and
generally in the Great Basin, are orogenic phenomena; the concavity of
the Bonneville Basin, whereby it is constituted an area of interior drainage,
is epeirogenic. Neither process of displacement belongs exclusively to the
remote past, but both are associated with the lake history. The e\adence
of this association is of three kinds, consisting (1) of the phenomena of
faults, (2) of departure of shore-lines from horizontality, and (3) of the
anomalous ])osition of Great Salt Lake.
EVIDENCE FROM FAULTING ; FAULT SCARPS.
In the district of the Great Basin the characteristic structure of mount-
ain ranges is one in which faults play an important part. Foldings of
strata are not wanting, but the greater features of relief appear to have
' Seo iioto on page 3.
340
OROGENY AND EPEIROGENY. 341
been wrought by the displacement of orographic blocks along lines of" fault.
Sometimes a mountain range consists of a great block of strata cut off along
one side by a profound fault, and inclined in the opposite direction until it
descends beneath the plain constituted by the alluvial deposits of the adja-
cent valley. More frequently there are other faults within the range, trend-
ing parallel to its length, and having throws on the same side with the throw
of the greater fault at the base.
It was probably these internal faults which originally suggested the
structure of the ranges as faulted orographic blocks ; but the structure was
soon connected with a certain set of topographic features, and came to be
recognized by means of these. A range consisting of a faulted block gen-
erally has a bold front on the side of the fault, and is less abrupt on the
opposite slope. On the side of the bold front the line separating the rock
of the mountain from the alluvium of the valley is simple and direct, while
on the opposite side it is tortuous. On the side of the fault the strata
usually dip away from the adjacent valley; on the opposite side, toward it.
It was not until after the structure had been discovered and described by
several geologists that the more decisive evidence afforded by the fault
scarp was brought to bear. The writer first became aware in the summer
of 1876 that lines of faulting may sometimes be traced upon the ground by
means of low cliffs or scarps due to displacement of so recent date that the
atmospheric processes of sculpture liave not yet restored the ordinary forms
of topographic detail. Since that time he has observed many such scarps
in various parts of the Bonneville Basin, and in other portions of the Great
Basin, and the observation has been still further extended by others,
especially by Russell.^
The observed fault scarps for the most part follow the outcrops of fault
planes whose position had previously been inferred from the configuration
of the adjacent mountains, but they have served also to betray a number of
faults whose existence might otherwise not be suspected. An illustration
of this is found on the west side of the A([ui range of mountains, where
the strata constituting the range dip down apparently beneath the allu\ium
' Fourth Ann. Kept. U. S. Geol. Survey, pp. 445, 448," 449, 452. Geological history of Lake Lahon-
tan, Chap. X.
342 LAKE BONNEVILLE.
of Skull viillcv. The typical aspcft of the faulted mountain front is here
wanting, and the actual fault, demonstrated by a superficial scarp, naturally
escaped the attention of the geologists who have described and ligured the
structure of the range.
A case of more frecpient occurrence is that in which the fault along the
base of the range is compound, one portion following the visible edge of
the rock, and another portion lying some furlongs or even some miles val-
ley-ward. The orogenic block between the two fault planes lies far lower
than the one constituting the mountain range, and may be far higher than
the one beneath the valley. Occasionally some portion of it is visible, but
it is usually completely buried by the alluvium constituting the foot slope
of the mountain, so that the surface affords no intimation of its existence,
unless some recent faulting records the position of its margin l)y a scarp.
It was at the base of the Wasatch Range that the fault scarj) was iirst
discriminated as a distinct toi)ographic feature, and up to the jjresent time
that range has afforded the best illustrations. A descrij)tion of the phe-
nomena there exhibited will now be given somewhat in detail, following
the order from south to north. It should be premised that the fault scarps
were at no time a leading subject of investigation; the region was traversed
upon other errands, and the faults were obser\ed incidentally. The record
therefore, although involving much detail, is far from full or exhaustive.
The Wasatch Range, using the term in the most restricted sense, may
be said to extend from the town of Nephi, near which it culminates in Mount
Nebo, northward to the Gate of the ]leav River, where its axis is ver\' low.
The geireral course is a little west of north, and there are two angles just
north of ]\rount Nebo, which have the effect of offsetting the axis some
miles to the eastward. Near the town of Santa(pnn there is a low spur
projecting westward and continued across the valley in a line of hills.
Forty miles farther north a higher spur, kno\A-n as the Tra\erse Range, runs
westward. A third spur lies just north of Salt Lake City, and a fourth a
few miles north of Ogden, near the town of lionneville. These orographic
features and tlic i)()sitions of the localities described in the following para-
grapli can be lu'st made out b\- the aid of the large map ol Lake Bonne-
ville.
FAULT SCARPS. 343
From Nephi to the pass near Santaquin the range is lofty, and has a
rather high alluvial foot slope toward Juab valley. At a variable distance
from the mountain base this foot slope is traversed by a fault scarp from
ten to thirty feet in height. It is for the most part single, l)ut in places it is
divided into two parts, and it was observed at several points to fade out,
being coincidently replaced by a similar scarp a few rods up or down the
slope, and lapping past it. Toward the north it swings nearer to the mount-
ain base, and it was finally seen to leave the valley altogether and strike
across the neck of the Santaquin spur. Juab Valley lies at such an alti-
tude that the water of Lake Bonneville covered only its lowest part, and
the shore-lines lie far lower on the slope than the fault scarp. There is thus
no direct relation establishing the order of sequence of the lake and the
displacements, but the relative recency of the last displacement is inferred
from the state of preservation of the scarp.
Evidence of faulting was next seen in the ancient deltas on the Spanish
Fork, deltas lying in the reentrant angle produced by the inflection of the
mountain axis north of Mount Nebo. There were distinguished two deltas,
synchronous with the Bonne^^lle and Provo shore-lines, the Bonneville delta
being widely trenched by erosion and containing the head of the Pi'ovo
between its surviving segments. The fault scarps are numerous, producing
a confused topography, and their zone is at least a mile broad. The majority
traverse the upper delta only, and the abrupt manner in which certain
scarps terminate at the edge of this demonstrates that they were produced
after the formation of the upjier delta and before the completion of the
lower. The greatest throw of a single fault observed on the upper delta
is more than 150 feet; the greatest throw on the lower delta is about 40
feet. The throw of all the faults is toward the went, but the strips of delta
plain lying between the parallel faults are inclined toward the east. The net
displacement was evidently such as to increase the height of the mountain
with reference to the \-alley, but its amount was not ascertained. Thence to
Hobble Creek, five miles, the zone of displacement follows the margin of the
alluvial slope where it adjoins the mountain face, and usually includes from
two to half a dozen fault scarj^s. These in the main trend parallel to the
base of the mountain range, but a few scarps depart from it at high angles.
344 LAKE BONNEVILLE.
At Hobble Creek the fault scarps are numerous, and tlicv are well
exhibited on tlie surface of the Bonneville delta. Their total tln-ow was
estimated, \\itli the aid of an aneroid barometer, to be 125 feet. Their
states of preservation indicate that they are of varifuis dates, and the latest
formed is so fresh that vegetation has not yet entirely covered its slope.
A little farther north a fault is seen to traverse a beach line of the Inter-
mediate series, giving the contiguous portions of the l)eacli a difference in
altitude of about thirty feet.
Near the city of Provo, a small mountain torrent issues from a gorge
called Rock Canyon. At the mouth of the canyon is a delta terrace at the
Bonneville level, with a radius of about 1,700 feet, and divided midway by
the stream. The stream has opened a passage several hundi'ed feet broad,
and is flanked on one side by a stream teirace. The greater portion of the
delta terrace on both sides of the stream is corrugated by faulting, being
ridged to such an extent that elevated aqueducts have been resorted to in
conducting water over it for purposes of irrigation. Figure 42 exhibits two
Fig. 42.— Profiles (1,000 feet apart) of the Kock Canton Delta, illustrating its displacement by F.aulting
measured profiles traversing the southern half of the delta at right angles to
the strike of the fiiult scarps. If the reader will bear in mind that these
deltas are normally characterized by simple profiles, sloping with great uni-
formity from apex to margin, he may obtain from the diagrams some idea
of the nature of the irregidarities introduced by fixulting Tlie rods; of the
mountain is indicated at the right, and tlic cliff, a, at the extreme left is that
belonging to the margin of the delta The |)ositions of faults are shown liy
vertical broken lines, and the letters h c d c mark fault scarps wliich traverse
both lines of section. The lines of section are alxiut 1.0(10 feet apart, and
FAULTS AT ROCK CANYON.
345
their differences fairly represent the ordinary variahiHty observed in the
details of fault belts when followed in the direction of their strike. A little
farther north thnn the position of the upper profile the faults h and c
approach each other, and the fallen block between them wedges out.
Where they join, the trough gives })lace to a ridge about five feet high, and
this ridge, after running a short distance on the plain of the delta, reaches
the edo-e overlooking- the stream and follows down the stream cliff to the
flood plain. A portion of the fault scarp d likewise descends the stream cliff,
but all the other scarps of the terrace end at its northern margin. It thus
appears that the greater part of the displacement took place before the creek
performed its last work of lateral corrasion on the south side of its channel,
but that two of the movements are of later date The ])henomena are of
special interest because they exhibit the hades of faults, features very diffi-
cult of observation where the faulted material is alluvium. The hade is
nearly vertical, but inclines slightly toward the valley. These features are
shown in Figure 43, in which the stream cliff is represented as seen from
Fig. 43. — South half of Rock Canyon Delta, showing Fault Scarps.
the north, the artist standing on the northern half of the divided delta and
looking across the valley of the stream. The creek itself is hidden liy a
stream teiTace which occupies the foreground of the sketch, and it will be
observed that this terrace is likewise traversed by two small faiilt scarps,
facing each other. Their height is only from two to four feet, and by
346 LAKE BONNEVILLE.
contrast with tlie greater scaqis on tlie dc^lta teiTace beyond, tliey serve to
show how small a portion of the entire disturbance has occurred since the
principal excavation of the stream channel.
The next observation was made at the American Fork, ^hicli debouches
from the moiintain twelve miles farther north. There, too, a delta of the
Bonneville shore-line is centrally divided by stream erosion. Both halves of
the delta are traversed close to the mountain base by a fault scarp GO or 70
feet high. The same displacement traverses the flood })lain of the stream,
but its throw there is only 15 feet, showing that the entire displacement of
the delta was not accomplished in a single movement. The last disturbance
of the flood plain was so recent that a rapid still marks the acclivity it pro-
duced in the bowlder-paved stream channel.
A few miles northward the scarp was seen to traverse the Pleistocene
alluvial plain at the mouth of Dry Canyon, and also the moraine with which
that plain is associated. This locality is close to the jwint where the Tra-
verse Range joins the Wasatch, but the fault was not traced far enough to
ascertain its relation to the junction. There can be no question, however,
that the great fault passes between the two ranges, and it is jirobable that a
recent movement has characterized it here as elsewhere. On tlie north side
of the Traverse Range the fault scarp at the base of the Wasatch was traced
quite to the junction and seen to rise in the groin between the two masses.
In the next ten miles northward, there issue from the Wasatch three
creeks, known as Dry Cottonwood, Little Cottonwood, and Big Cotton-
wood,' and the fault was continuously traced by its scarps past all these.
In the vicinity of the streams and in the intervals between them the surface
disturbances are complicated, and for a distance of about 5 miles there run
op])osing scarps, between which a block has been depressed. At the mouths
of Dry Cottonwood and Little Cottonwood canyons the scarps cross a sys-
tem of moraines, described in Chapter VI and represented in PI. XLII, and
materially modify their forms. The lateral and terminal moraines of Drv
Cottonwood Canyon originally constituted a loop, the extremitA' of \\ liicli
was notched by the creek. The depressed block, traversing the latcial
moraines, has carried doAvn segments of them, leaving the distal portions as
' In PI. XLII tlio name " Big Cottonwood " is erroneously attached to Dry Cottonwood Creek.
U S. GEOLOGICAL SUF.VEY
IlAKE BONNEVILLE, PL.XUI
MAP OF THE
M () r T II s
111--
LITTLK .\N7) DRY COTTONWOOD CANONS,
At Ihc Wi-slcni IJasc ul' llir Wasalc li Movuilains, I'Lili , VV
shewing
GLACIAL MOIJAINKS ANI1 FALL T S
Topography I'v lUIberr Tlionipsoii
Cc'oIo^Sv bv OK Gilbert
Ltitcrnl tiitil Ttrnnn*tl v
ICjOO
SCALE 't^ ^ ^ r
2000 3000
--^— : FEET
S{)-/fe^ Ion. U'li r
.IuUu« Ilicn ft I'o.Iith
DriiwTi by li TliouipS'
w.'
FAULTS AT THE COTTONWOODS.
347
Fin. 44.— Profile of the South Moraine at the mouth of Little Cot-
tonwood Canyon, ahowing the effect of Faulting.
a pair of outlying hills. 'I'lic .southci-u lateral moraiiiu of Ivittle Cottonwood,
an acute and originally sj-minetric ridge, has assumed the profile repre-
sented in Fig. 4*4. Tlie iiortlieni lateral, being broad and Hat, exhibits a
conspicuous trench where
crossed by the depressed
block (see PI. XLIII). The
walls of this trench are
among the freshest of the
fault scarps, being bare of
vegetation along their upper courses, and in places too steep to be climljed.
(_)n the side nearest the mountain their height is from 40 to 60 feet. Here
again it is evident tliat the total displacement was accomjjlished by a
series of efforts, for lietween the two moraines the phenomena of the
depressed block appear in the alluvial jilain of Little Cottonwood Creek,
and the greatest scarp in the plain has a height of only 20 feet. At Big
Cottonwood Creek the total displacement is about 40 feet, and at a ])oint
between the two streams a single scarp was observed with a throw of 100
feet. Fig. 45, gi"v"ing a profile of fault scarps near Big Cottonwood Creek,
is not based on measurement, but
reprodtices a rough field sketch.
It is probable that faults traverse
the ancient deltas of Little C'otton-
wood Creek at a distance of some
miles from the moinitain base, but this fact was not fully established.
From a point about one mile noi-tli of Big Cottonwood Creek to Salt
Lake Cit}^, a distance often miles, the fault records are obscure, and it is prob-
able that there have been no very recent movements. No scarps at all were
seen close to the rock of the mountain. It was thought, that an old one
could be traced a short distance along the middle of the alluvial slope below
Fort Douglas, and there is a more decided indication at the foot of the same
slope in the eastern suburbs of Salt Lake City. Both of these are ancient
as compared with the scarps previously described, and they may even have
been washed by the later waters of Lake Bonneville.
Fig. 45.— Profile of Fault Scarp.s near Big Cottonwood
Canyon.
348 LAKE BONNEVILLE.
Salt Lake City is built just soutli of a spur which jji-qjects four or five
miles westward from the front of the Wasatch. Tliis spur rcpi-esents an
orogenic block distinct from that of the main range. It is separated from
the mountain mass by a fault plane along which the Wasatch block has,
relatively speaking, risen, and it is separated from the valley on the remain-
ing three sides by a curved fault plane along which the block underlying
the valley has, relatively speaking, fallen. The first of these faults has been
determined from the rock .structure, as I am informed by Mr. J. E. Clayton
of Salt Lake City. It is also indicated at its northern end by a fault scarp,
which can be traced for a short distance up the groin. The fault on the
side of the valley is exhibited at the west and northwest by a series of
scarps, which begin in the northern suburbs of Salt Lake City near the
Warm Springs. At this point the flat alluvial plain of the Jordan reaches
the steep rock face of the spur, the line of separation being marked by an
abrupt change of slope. A little north of the springs there can be seen
clinging to the rock at a height of 40 feet a line of conglomerate fragments,
formed within the plain by the cementation of debris to the limestone, and
brought by faulting into the present position. The surface of the plain
below is thrown by the same faulting into irregular waves, and at one point
it is distinctly terraced. On one of the faulted benches an ore-reducing
establishment has been built, utilizing a lower bench as a dmTiping ground
for its slag. Between this point and the liot spring an alluvial cone, Ijuilt
against the face of the spur, is traversed by a typical scarp, which was
sketched by Mr. Holmes. Tlie sketch is reproduced in PI. XLIV, where
may be seen not only the scarp but its relation to other elements of the local
geologic history. The face of the spur consists of a paleozoic limestone,
inclined at various high angles. The horizontal terraces it liears are shore
marks of the ancient lake. It is evident that the principal features of its
relief had been carved before the production of these terraces, so that the
main displacement — that to which the spur owes its origin — nuist have
occurred long before the Bonneville epoch. The alhn ial cone may or may
not have been constructed before the epoch of the lake, but by the absence
of shore-lines and lake beds from its surface we are assured tliat its outer
layers at least are of post-Bonueville deposition. The disi)lacements pro-
U. S. GEOLOGICAL SURVEY
LA^:e eOflNEVILLE PL, XLIV
V
.>
'^"
^0Mi^l^
'%■
'"^•-\\-
R^
-t0B-'N}'£!KH.l- S'c'^ts-s
FAULT SCARP CROSSING ALLUVIAL CONE, NEAR SALT LAKE CITY.
Drawn by W. H. Holmes.
FAULTS NEAR SALT LAKE CITY. 349
ducing the fault scarps are therefore subsequent not only to the lake but to
a certain amount of post-lacustral alluviation.
The portion of the alluvial cone that lies above the fault scarp is chan-
neled by the stream, and a study of the system of terraces bordering this
channel shows that the total displacement of 30 feet was produced by at
least tln-ee independent movements, the measures of the parts being 15 feet,
5 feet, and 10 feet.
At this point and elsewhere in the vicinity the scarp is utilized by
burners of lime, who construct their kilns against its face and use the
terraces above and below for the two approaches needed in the man-
agement of the kilns. The proprietor of the kiln represented in the plate
enjoys the further convenience of quarrying his limestone from the adja-
cent cliff.
The hot spring at the apex of the spvir is on the line of the fai;lt, and
a scarp can be traced from it in either direction. The powder houses stand-
ing a little farther northward are partly above and partly below the fault
scarp. Many of the fault features in this vicinity, including those figured
in PI. XLIV, may be seen from the car windows of trains passing between
Salt Lake City and Ogdeu.
From the point where the spur joins the main ridge northward to the
ancient delta of the Weber, a continuous scarp follows the mountain base,
its throw ranging from 25 to 75 feet. Opposite the village of Farmington
its course is less direct than the trend of the mountain front, causing it to
ascend and descend the narrow alluvial foot slope in the manner represented
in Fig. 46. The broad Weber delta, which belongs chiefly to the Provo
epoch, is crossed from side to side by the scarp, the general throw being
from 40 to 50 feet. A recent alluvial cone resting upon the southern half
of the delta has suffered a displacement only one-third as great as the adja-
cent delta. On the northern half of the delta the scarps constitute a sys-
tem similar to that in the delta of Rock Canyon, and there are transverse
branches running half a mile westward into the plain. At one point the
falling of a block has produced on the surface a closed basin, which with a
little artificial improvement has been made to serve for the storage of water
for irrigation.
350
LAKli BONNEVILLE.
Thence to North Ogden Canyon scai7)s were seen at numerous points
usually in (>'rou])s of two oi- more. Fig. 47 gives iiii iiunicMsunMl prnliU
Fig. 40.— Sh.'u- luir,-, .uj.l I'.uili Sc.up .a iiulns, ,,i ii.r W',.,.,.,
(■ill F.iriiiiii^tuii, i'
Fig. 47.— Profile of Fault Scarps near Ogden Canyon, Utah.
across the displacement near Ogden Canyon, and contains an extreme illus-
tration of the reversed slope frequently given to blocks of alluvium between
parallel faults. A few miles
farther north a small closed
basin has been foriiu'il in this
manner. In the same vicinity
one of the fault scarps crosses
the line of the Bonneville shore terrace, dis})lacing it about 20 feet.
At North Ogden Canyon the axis of the range turns westward for a few
miles, and then resumes its northerly course. At the salient angle a low-
spur is apijended, similar to that at Salt Lake City, ]:)ut of smaller dimen-
sions. The scar]) runs bcliiiid the spur, and none was seen alx.ut its tare;
but it can not In- doubted that its boundai-y on the valley side also is deter-
mined liv a fauh. .V hot spring rises near its western l»ase. 'riieiice north-
FAULTS IN CACHE VALLEY. 351
ward to the town of Willard the fault scarp follows the mountain base with
an average throw of 20 feet, and it gradually diminishes and disappears
before reaching the next settlement, Brigham City. Beyond Brighani City
a single locality only, near the settlement of Honeyville, gave evidence of
recent movement on the plane of the great Wasatch fault.
The total distance from Nephi to Honeyville is 125 miles, and it is
probable that more than 100 miles of that distance is characterized by post-
Bonneville ftiult scarps. The average displacement is 30 or 40 feet.
North of Honeyville the crest line of the Wasatch falls so low that it
was overflowed by the Bonneville waters. The axis rises beyond into a
range of importance, Ijut the name Wasatch is not there applied. If the
western margin of this range is determined by a continuation of the Wasatch
fault, no record of the fai-t was observed in recent scarps. A few scarps were
seen on the opposite (eastern) side of the range, especially in the vicinity
of Clarkston. Twenty miles farther north, and approximately in the same
structural trend, there itre fault scarps at the western margin of Marsh Val-
ley, but these are outside the Bonneville Basin.
The fault mentioned at Clarkston follows the western margin of Cache
Valley. The eastern wall of the valley is an important mountain range,
whose bold western front has the topographic configuration of a worn fault
cliff. At its base there are obscure indications of late movements, either
during or just after the lake epoch, and at one point, near Logan, a post-
lacustrine fault scarp crosses a delta of Provo date. The displacement is
about six feet. At the north end of the valley a " weathered scarp was
observed near the base of the alluvial cone of Marsh Creek, close to the
outlet channel of Lake Bonneville. The direction of its throw indicates
that it belongs to the eastern side of the valley, but it is several miles from
the mountain front proper.
The range bordering Cache Valley on the east extends southward
parallel to the Wasatch, and exhibits in Morgan Valley, at its intersection
by the Weber River, an old fault scarp, judged from its imperfect preserva-
tion to be pre-Bonneville.
Passing west of the Wasatch meridian, we have at the north a single
instance of recent faulting. The small range lying east of the town of Snows-
352 LAKE BONNEVILLE.
ville is marked at base by a low scarp, — a scarp more defaced by erosion
than are the Bonneville terraces lower down on the same slope. In tlie
same meridian and far to the south are the fiiults described in the last chap-
ter as associated with the Ice Spring craters. They are probably referable
to the volcanic phenomena rather than to those of mountain uplift; and the
same remark applies to a scarp observed by Mr. Russell 20 miles farther
south.
Midway between these are two fault lines, associated with the Oquirrh
and Aqui ranges. These ranges are parallel to each other and to the Wa-
satch, and agree with that range in having their main lines of displacement
on the western side. The scarp at the western base of the Oquin-h runs
southward from Lake Point a distance of four miles, exhibiting a throw of
25 feet. Its position is at the base of the pteep mountain face, and the Bonne-
ville and Provo terraces are carved in the x'ock above. It was next seen
a few miles farther south, where it follows the contour of an embajnuent of
the mountain side. It is there partly above and partly below the level of
the Bonneville shore-line. Near the town of Tooele it appears to strike
across a transverse spur, reappearing southward at the mouth of what is
called Dry Canyon, and continuing thence to East Canyon and the canyon
which contains the mining hamlet of Lewiston. At the mouth of East Can-
yon it intersects alluvial terraces in such way as to show two separate
movements with an aggregate tlu'ow of 50 feet. Although the course of
the scarp was not traced, it is believed that it could be followed continu-
ously for a distance of 25 miles. The southern portion nms above the hor-
izon of the lake shores, and is therefore not directly comparable Avith them, .
but it is considered probable that post-Bonneville movements have occurred
at all points of observation. The scarp on the Aqui Range is low, and
there is small basis for judgment as to its date. It was best seen in the
vicinity of Knowlton's ranch.
Following westward along the system of ranges which separate the main
body of Lake Bonneville from the Sevier body observation is purely nega-
tive until the House Range is reached. It is proper to say, however, that
so much attention was given to mountain foot slopes in connection witli the
study of shore-lines that the absence of notable fault scarps may be asserted
U S.GBOLOGICAL SURVEY
LAKE BONNEVILLE PL. XDV
i
113°
112°
111
111°
Julius Bicn i t'o, Ulh
Drmm bv G.TI...uipi«
FAULTS OF WESTERN UTAB. 353
of the southern portion of the Cedar Rang-e, of the eastern face of the Simp-
son and the western face of the McDowell, of Granite Rock, and of the
northern portion of the Dugway Range.
The Plouse Range was long ago recognized as a faulted monocline in
which the direction of displacement is reversed midway. The northern
third of the range exhibits a westerly dip, and is faulted along the eastern
base ; the southern part has an easterly dip and is faulted on the western
base.^ This determination was subsequently confirmed .by the discovery
of a \vell defined fault scarp in the vicinity of Fish Si)ring, and an obscure
and probably very ancient scarp at the western base of the southern division.
The next mountain body to the west is the Confusion Range, an
assemblage of small ridges, and associated with these a, single scarp was
found. This lies near Knoll Springs, on the east side of Snake Valley. It
is low and worn, and follows the rock base closely.
The Deep Creek Range, which forms part of the western boundary of
the Bonneville Basin, is faulted on both sides. In the vicinity of the old
overland road crossing the ridge from Willow Spring to Deep Creek settle-
ment, to which vicinity observation was restricted, the range is flanked on
the east by a broad and high alluvial slope. No fault scarp was seen, but
near the lower margin of the slope a partial section of the lake sediments
shows that they were disturbed during the period of their deposition. The
Yellow Clay at one place suifered uplift and erosion before the deposition of
the White Marl, so that there is unconformity of dips, and at another point
the Yellow Clay and White Marl together are so greatly disturbed that their
inclination is toward the mountain. The superficial topograjihy that must
have been created by these disturbances was obliterated by wave work,
and at the locality of the section the upper edge of the inclined block was
planed away in the formation of a terrace of the Provo shore.
On the west side of the range an ancient and nearly obliterated scarp
crosses the alluvial slope near its upper edge. On the opposite side of Deep
Creek Valley a better preserved fault scarp follows the eastern base of the
Gosiute range. It lies far above the Bonneville shore-line, and was not
critically examined.
' Surveys West of the 100th Meridian, vol. 3, pp. 27-28.
MON I 23
354 LAKE BONNEVILLE.
GENERAL FEATURES OF FAULT SCARPS.
Except in the yolcanic district of the Sevier Desert, the fault scarps
follow the bases of mountain ranges or run })arallel to them. Where there
is but a single scarp, it invariably fiices toward the valley and away from
the mountain. Where there are several scarps, frequently one or more face
toward the mf)untain, but the one nearest the mountain always faces toward
the valley, and the net displacement is always of such nature as to inci-ease
the height of the mountain with reference to the valley. The mountains
are rising ar the valleys sinking.
The scarps are rarely found at the contact of the rock of the mountain
with the alluvium of the valley; they usually occur in the alluvium several
scores or lumdreds of feet from the contact. The segments of alluvial plain
included between parallel scarps rarely retain their original slope. In a few
instances, and for short distances, their rate of descent toward the valley is
increased by the disturbance, but as a general rule the slope valleyward is
diminished, or even i-eversed. The tendency of the dissevered blocks to
incline away from the side of the downthrow is almost as pronounced as in
the case of land slides. The assumption that the attitudes of these alluvial
surfaces are representative of the attitudes of large down-reaching masses
continuous with them seems untenable, because such masses would mutually
interfere.
The hade of a fault is usually difficult of determination unless expo.sed
by mining operations, and the difficulty is peculiarly great where the walls
are of incoherent detritus. The freshest of tlie fault scarps have some talus,
and prove only that the hade does not depari widely from verticality. The
best observation w^as made in the Rock ('nnvon delta, where, as already
described, several scarps descend a stream cliti' standing at tlu- angle of
stabilitv. They show a hade toward the valley of less tlian li\ e degrees.
That this approximate verticality is more than a superficial feature of
the great Wasatch fiinlt, is seri(iusl\- ([uestioiied, for several reasons. In
the first place the faults witliin the Hasin Ranges, so far as niv observation
shows, hade at consideralih- angles, and it is liiglily probable that this fault
belongs to the same system. Second, tlie secular motion of the mountain
being upward with reference to the valley, it is prol)able that the roek face
THEORY OF FAULT SCARPS.
355
at the contact Avith alluvium lias lieeu little Avasted by erosion, and is essen-
tially the protruded foot-wall of the fault, and if so, the visible fault iu
alluvium is not in the plane of the great fault, but is a branch with less
hade. Finally, the last hypothesis affords an easy explanation of the super-
ficial details of the faulting, as will appear by the following explanation.
Fig. 48 is constituted of four diagrams illustrating the supposed method
of faulting. In the first diagram the line ,r ij represents in section the
Wasatch fault, with an assumed hade of 30°. To the right of this line is
Fig. 48. — Diagram to illuatrate Theory of Grouped Fault Scarps in Alluvium,
the firm rock of the mountain, its surface being somewhat reduced by ei'O-
sion above the point a, where the alluvial slope of the valley side adjoins it.
To the left of the line x y the material represented is detrital and incoherent,
being chiefly alluvial. The alluvial sui'face previous to the last faulting is
represented by a c. The direction of motion in faulting is parallel to the
plane x y, and the plane of motion is assumed to coincide Avith that plane
up to the point c, and then curA-e to &, so that a triangular pi-ism of allu-
vium, ft h e, remains attached to the rock, constituting the foot-Avall of the
fault. This movement opens a fissure, h e (J. The material traversed by it
being incoherent or feebly coherent, the fissure cannot remain open, but is
immediately filled by the settling of one or both of the Avails. The remain-
ing three diagrams indicate hypothetical methods of closing the fissure. In
the second diagram it is supposed that the hanging wall yields Avithout defi-
nite fracture, Imt l»y differential moA'einent distributed throughout tlu* mass,
so that the triangular prism included between the points // d e is made to
assume the form and position // ./' e. There then remains a fai^lt scarp, h f,
giving an exaggerated measure of the actual throAv of the fault h d, and
35(j LAKE BONNEVILLE.
accompanied at its base hy a reversed inclina,tion of the surface/// In
the third diagram it is assumed that the hanging wall is divided by a fract-
ure, /; e, and that the prism h d c settles and spreads so as to occupy the
space i k e. There result two fault scarps, h k and Ji '/, facing in opposite
directions and api)roximately representing l)y their difference the true throw
h (J. The fourth diagram supi)oses that the triangular prism h I o in cleaved
from the up})er part of the foot-wall and slides down so as to take the posi-
tion m n e. This gives two fault scarps, / n and m d, whose sum would
ordinarily att'ord an overestimate of the actual movement of the great fault
plane. If now we consider that there have been repeated movements along
the same general plane of faulting, and that these repetitive displacements
have often divided the alluvium in different places, it becomes evident that
these hypothetic elementary profiles can be so combined as to jjroduce all
the complicated profiles actually observed.
While, as just mentioned, a number of successive movements may occa-
sion the same number of separate scarps, they may also coincide in locus
and produce but one, and it is probable that coincidence is the rule. In
general, each scarp represents a series of distinct movements.
Indeed, so far as the phenomena of the Bonneville Basin instruct us,
the process of faulting might be conceived as one of continuous sl(i\\- motion,
and it is only through the phenomena of earth(piakes in other districts that
we become acquainted with the rhythmic and paroxysmal nature of dis-
placement on surfaces of fracture. The features of the fault scarps accord
fully with the general theory that the growth of mountains is a gradual
])rocess, secular in duration, though (•atastrophic in detail.
The freshness of some of the scarps points to an anti(puty measured in
>ears rather than centuries. A large number have l)een ])roduced since the
final retirement of the Bonneville waters. A few were synchronous wilh
the I'rovo shore-line. One movement l)elongs to inter-lSoiniexille time. ( )t
earlier dates, nothing can be said with precision. Inside the lake area, it
is to be sujjposed that scarps older than the Bonneville shore-line were olilit-
erated l)^- littoral sculpture and lacustrine sedimeiitatiiin. ( tutside the Bon-
neville shore-line the only discovered index of anti(piity is the state of pres-
ervation, a criterion affording no precision. Discrimination is further em-
OLD FAULTS AND YOUNG. 357
barrassed by the recunviict' of ilisplncemeiit nloiii;- tlic same lines, so tlint
tlie qualified indications of date in the preceding pages apph' as a lailc onl\-
to the latest of the local movements.
LOCAL DISPLACEMENTS VERSUS LOCAL LOADING AND UNLOADING.
The phenomena of earthquakes indicate that the orogenic forces, what-
ever they may be, slo\vl\- generate and accumulate strains in the crust,
until finally the cohesion or static friction is overcome, and a sudden Nield-
ing results in a fault and an earthquake. In such a district as the liomie-
ville Basin, where the planes of faulting, su})erficially at least, are approxi-
mately vertical, it seems probable that the determination of rupture may be
hastened or retarded by anything affecting the weight of the orogenic block
on either side of the plane of movement. It is coimnonly held by students
of physical geology that the degradation of the uplifted block and the accu-
mulation of sediment on the downthrown block constitute an unloading and
a loading, which consijire with and aid the forces primarily concerned in the
displacement, and it is maintained by some that when once the displace-
ment along a great fault line has been initiated, the process of loading and
unloading is competent to continue the depression of the lower block and
the upheaval of the higher without further aid from the forces that initiated
the disturbance. Now the filling of the Bonneville Basin with water added
a very considerable weight to the vallej's, and therefore to the down-thrown
blocks, and made no corresponding addition to the uplifted blocks repre-
sented in the mountain ranges. The contemporaneous glaciers were indeed
sustained by uplifted blocks, but these were restricted to a short section of
the Wasatch, and in that section their weight was much less than that of
the water in the adjacent valley.^ It is therefore theoretically conceivalile
that during the presence of the lake the pi-ocess of faulting along the.mount-
ain bases was stimulated, and that after the evaporation of the water the
process was corre.spondingly retarded. That the load of water was quanti-
tatively sufficient is readily shown. If the transfer of rocky matter from
the mountain block to the valle)' block is the cause ordinarily operative in
'The ,irea of ice on tbo Wasatch Range inay be compared with the contemporaneous area of
water in Lake Bonneville by reference to PI. XLIX. The areas of ice there represented on the Wasatch
and Uintah Mountains are copied from Kin^^'s map in Volume I of the Fortieth Parallel Report.
358 LAKE BONNEVILLE.
generating the stress which renews movement along the fault plane between
the blocks, then the dejjth of rock necessary to be removed from one block
and added to the other in order to overcome the adhesion on the fault i)lane
is measured by one-half the resulting movement. For the Wasatch range
this measiu-e is less than five feet. The load of water held by the valley
blocks was e(|ui\alent in the vicinity of Great Salt Lake to a layer of rock
of the density of the surrounding mountains and with a tliickness of 300
feet, and at the Provo stage the load of water wns equivalent to 200 feet of
rock. The stress due to the water was therefore many times greaU'v than
that needed to over})ower the adhesion, and the load of A\iiter was com-
petent to act, provided the erogenic blocks possessed the tlieoretic susceji-
til)ilitv to lonil.
If tlie orogenic blocks rest on a ])lastic substratmn, or if thev are oth-
erwise conditioned so as to obey the hydrostatic law and yield freely to
external stresses, then the valley blocks should have been depressed several
hundred feet by the adilidon (if the water, should have partially recovered
from this depression during tlie abrupt lowering of the lake from the Bon-
neville shore to the Provt), and should have risen still further during the
final desiccation of the basin, except in regions where the orogenic forces
operated Avitli sufficient rapidity to counteract the tendency. Instead of
this, we find that the post-Bonneville movement of the valley blocks,
wdierever it has occurred, has been one of depression, and so far as the
})henoraena go we find no evidence that the depression of the valleys was
more rapid during the epochs of tha Bonneville and Provo shores than it
has been in more recent times.
We are forced to conclude that the mountain ranges of the Bonneville
Basin and the valle}'s between tlicin do not, with reference to each other,
obey tlie law of flotation.
It follows with eqiud cogency that the faults do not penetrate to a
layer characterized by fluidity or semi-fluidity — implying by these terms
the ])ower to flow under small shearing strain — but terminate in a region of
rigidity — im]dving by that term the ability to withstand relatively large
shearing strain. I conceive them to ternnnate at the up])er limit of the
i-egiou of plasticity by pressure — implying by that phrase that at and below
FAULTING INDEPENDENT OF LAKE HISTORY. 359
»
a certain deptli the rocks of tlie crust, liowevor riyid, iire subject to such
pressure that their j'ielding under shearing strains exceeding tlie ehistic
limit is not by fracture but l)y flow. I conceive the orogenic blocks as
confluent with the subjacent layer, excepting such as may wedge out by
the convergence of fault ])lanes.
MOUNTAIN GROWTH.
The height of ;) mountain, considei'ed as a to])ographic feature, is the
altitude of its crest, not above sea-level, but above the surroiuiding country.
From this ])oint of view it is pertinent to inquire whether the mountains of
the Bonneville basin are now growing. The C[uestion is more easily asked
than answered, but its consideration may not be unprofitable even thougli
the residt is indefinite.
In the case of mountains whose uplift takes place along faidt i)lanes,
the amount of faulting is a measure of the uplift. If the faulting is at one
margin only and the f)ther margin suflers no displacement, then the general
uplift above the adjacent valleys is one-half the uplift at the fault lines.
The processes of degradation tend constantly to pare away the mountain
top and thus reduce its height, and in the district under consideration tlie
processes of valley sedimentation likewise reduce the mountain height by
building up the valleys and thereby raising the plane of reference. When-
ever and wherever diastrophism is the more active, the mountain grows;
when degradation and sedimentation are moi'e active, the mountain becomes
smaller. The post-Bonneville faulting of the Wasatch Range is restricted,
so far as known, to the western base, and there amounts to about 40 feet.
Tlie general u])lift of the range may therefore be taken at 20 feet. Tlie
product of the simultaneous degradation of tlie niount;iin finds its way to
Utah Lake and Great Salt Lake, where its coarser j)art is accumulated in
the deltas of the Provo, the Jordan and the Weber, while its finer j^ortion
is spread over the lake bottoms. P)ut the deltas and lake beds afford no
simple measure of the mountain waste, for the same rivers receive also
detritus from other land areas, and in the same lakes are gathered the silts
from other streams. The deposits, moreover, are unex])lored, and if they
were explored, it would be no easy matter to discriminate the post-Bonne-
360 LAKE BONNEVILLE,
ville deposits from the Bonneville beds beneath them. The problem might
be attacked by a consideivntion of the annual outwash of the mountain tor-
rents, but if this difficult measure were made, we should still need to know
the antiquity in years of the last Bonneville flood, a factor for the present
entirely unknown.
But though a categorical answer is unattainable, a qualified result is
not necessarily so. The recent uplift of the Wasatch Range is greater than
that of any other range in the basin. That of the Oquirrh may be one
half as great, but no other range is at all to be compared in this respect,
and many ranges show no fault scarps whatever. It may therefore be said
with confidence that if any range of tlie district is actually growing at the
present time, the Wasatch is growing, and this l)rings us to a theorem of
Powell's which here finds illustration. Powell pointed out' that a high
mountain is subject to more rapid degradation than a low one, and that the
rate of degradation is a geometric function of the height. It is therefore
impossible for a mountain to become tall unless it is uplifted rapidly, and
when uplift ceases or becomes slow, only a sliort measure of geologic time
is necessary to reduce the height. High mountains are therefore always
yoinig mountains. They may be constituted of very ancient rocks, — their
initial uplift may have taken place at a remote date, but the great upheaval
which produced the present movmtain is geologically recent. The Wasatch,
springing ])oldly from a base plain 8,000 feet below its pinnacles, is a young
range, and as its recent uplifting has been more rapid than that of any of
its neighbors, we may fairly assume that present uplift is in excess of pres-
ent waste, and that the mountain is now growing.
EARTHQUAKES.
The extreme recency of tlie last orogenic movements in the most
populous portion of Utah, and the high ])robal)ility of their recuiTence
in the future, have a practical bearing as well as a scientific, for it is now
generally imderstood that earthquakes are due to paroxysmal yieldings of
the earth's crust, and it is e(|uall\- well known that tlie dangers attending
earthquakes can be greatly diminislu-d b\- precautionary measures. It is
' Geology of the Eastern Portion of the Uinta Mountains, by J. W. Powell, Washington, 1876,
p. 196.
FAULT SCARPS AND EARTHQUAKES. 361
indeed true that the fault scarps at the base of the Wasatch Mountams have
not been directly connected with earth tremors, but the association of
identical phenomena has been elsewhere observed. The earthquake of
1872, one of the most violent ever felt in the United .States, originated in
Owen's Valley, California, and its origin was accomjjanied by the sinking
of strips of land in such way as to jjroduce fault scarps identical in their
general features with those described in the preceding pages. The principal
scarp follows the base of the alluvial foot slope of the Sierra Nevada, and
has a maximum height of about 20 feet. Where this height is attained,
there is a coinpanion fault scai-p, 10 feet high, facing in the opposite direc-
tion, so that the net displacement is about 10 feet. At other points the
main scarp is associated with others miming nearly ])arallel and facing in
the same direction. As I saw them, eleven years after their formation, they
appeared little fresher than some of the Wasatch scarps.
The earthquake that shook Sonora and southern Arizona on the third
of May, 1887, produced a fault scarp which Avas critically examined by
Goodfellow and traced for a distance of 35 miles. It intersects the alluvium
along the base of a mountain range or ranges, and has an average height
of seven feet. Like the Wasatch scarp, it is often divided or furnished with
branches, but ludike that of the Wasatch it is exceptionally small where it .
intersects the alluvia of streams issuing from the mountains.^
The association of earthquakes with fault scar])s has likewise been
determined in New Zealand, where McKay and Hector not merely refer
certain scarps to earthquakes of the years 1848 and l^f)b, but recognize
them as the indices of modern slip.s on old planes of dislocation, and use
them in tracing out important structure features.''
- It is legitimate to infer that the belt of fertile vallevs tliat follows the
western base of the great mountain range of Utah is an earthquake district,
and this despite the feet that since its first settlement in 18.'')0 no impoitant
tremors have been recorded. It is a matter of geologic history that the
Wasatch range is gradually rising, and that this rise is not uniform in time
■George E. Goodfellow. The .Sonora Eartli(|u.ake; Scieuce. vol. 11, p. 102.
''Oil the geology of tlie eastern part of Marlborough Provincial district. By Alexander McKay.
In Colonial Mns. and Geol. snrvey of New Zealand ; Keports of Geological explorations during lo85.
Faults on pp. 129-133. Also James Hector, in same volume, p. xv.
362 LAKE BONNEVILLE.
and place, but is accom})lishe(l by small and sudden displacements more or
less localize<l, with intervals of rest. Of the lengths of these intervals we
have no means of judging-, and no one can predict the date of the next
movement, but it is beyond (piestion that such iiiovement will take ])lace,
and that when it occurs, the adjacent valley will experience an earthcjuake.
Neither is it possible to predict with great confidence what portion of the
district will be next affected, but if the orogenic force is approximately con-
stant and the rhythm in its visible work is due to the necessity for accumu-
lated energy to overcome friction, then the localities with fresh fault scarps
may reasonably be assumed to be exempt from faulting for a longer period
than those in which onl)- ancient fault scarps are seen. Reasoning thus, I
was led to sound a note of warning in Salt Lake City, which stands close
by an exceptional section of the range, where the fault scarps are so ancient
as to be largely obliterated.^ Its situation with reference to the growing
Wasatch is identical Avith that of Lone Pine with reference to the growing
Sierra Nevada, and it is largely built of adobe, a material ill suited to with-
stand earthquake shocks. In the village of Lone Pine every house was
thrown down by the shock of 1872, and 27 persons lost their lives, — a literal
decimation of the population.^
The relation of joints to the earthquakes of the Bonneville Basin is
discussed in the closing paragraphs of Chapter V.
EVIDENCE FROM SHORE-IilNES.
MEASUREMENTS.
The first precise determination of the height of the Bonneville shore-
line above the modern lake was made by the Wheeler Survey in 1X72, a
line of levels being run from Great Salt Lake to the old water mark against
the Wasatch range near Fort Douglas. In the same year Ilowcll of that
coi-ps observed the barometer on what was supposed to be the .same shore-
line at various points in the southern part of the Escalante Desert. The
'The warning was embodied in a letter to the Salt Lake City Tribune of September 20, 188:!,
afterward ropriiited in the American Journal of Science, 'id .series, vol. 27, January, 188-1, pp. ■I'.*-.'iX
-I iino'.e these (iKiiros from J. D. Whitney, who visited Owen's Valley a tew weeks after the
sliock and pnblished a careful and hijjhly valuable description of the phenomena. "The Owen's Val-
ley Earthquake", Overland Monthly, vol. 9, 16"'.', pp. 130-140 and 2C6-'278.
ESCALANTE BAY. 363
altitudes deduced from liis observations were about 300 feet iiiolier than
tlie altitude at Fort Douglas. Unfortunately, the barometric result was
not entitled to gi'eat confidence, so that only a presumption of difference of
altitude was established; but this presumption gave rise to two hypotheses,
which served in turn to direct subsetpient investigation. It was surmised
by Howell and the writer that changes might have occurred, since the epoch
of the shore-line,^ in the actual and relative altitudes of the diflierent points
measured, and it was suggested by King that the shore-line in the P^sca-
lante Basin might be found to belong to an independent lake, higher than
Lake Bonneville and tributary to it.^
Kin"''s suggestion led to a careful examination of the strait connectine:
Escalante Bay with the Sevier body of the old lake, and to the determina-
tion that it did not contain a river channel, but was occupied by standing-
water with an approximate dej)tli of 50 feet, and a width at the most con-
stricted point of about 2 miles. As will appear in a subsequent paragraph,
the synchronism of the Escalante shore-line with the Bonneville shore-line
of the more northerly basin has not been established, though the observation
at the strait renders it clear that the body of water occupying the Esca-
lante Desert was continuous with a body of water in the deeper basins at
the north.
The idea that changes in altitude have supervened since the production
of the Bonneville shore-line, opened a most attractive field of investigation,
for it seemed possible by measuring the height of the old shore-lines at many
points to obtain definite knowledge of the amount and distribution of the
post-Bonneville displacements of the earth's crust in the lake area. Earlier
quantitative studies of upheaval and subsidence had been practically
restricted to the sea coast, because there the ocean affords a datum plane
fpr measurement; but here was an oppt)rtunity to pursue similar inquiries
in an interior district.
In subsequent work every opportunity was improved for the deter-
mination of the present height of the records of its water surface. Meas-
urements were made with the engineer's level at points where the water of
Great Salt Lake could be conveniently used as a datum plane, and other
'Survey west of the 100th meridian, vol. :!, (i. 93. 'Geo!. Expl. 40th paralli'l, vol. 1, p. 491.
364 LAKE BONNEVILLE.
measurements where the same purpose was served by points on raih-oads.
At a few pohits Locke's hand level mounted on a , Jacob's staff was the
instrument used, and at other points triangulation w;is cnijjloycd with meas-
ured base lines. In some regions remote from good points of reference,
iind especially in the Escalante Desei-t, the ])arometer was emjdoyed.
S])irit-level determinations were made, not oidy of the height of the I'onne-
ville shore-line, but of the I'rovo. The local difference between the two
was also measured at some points where neither could l)e refeiTed to Great
Salt Lake. For the purposes of the investigation the altitudes of these
various points above the sea are iniimportant, since <^>nly their relations to
one another can be discussed, and it has been found convenient to refer
them all to the water surface of Great Salt Lake ; and since that surface is a
fluctuating one, a particular point has been arbitrarily assumed within the
range of modern fluctuation. That point is the zero of the "Lake Shore"
gauge. As the relation of the altitudes to sea level will not be again refer-
red to, it is proper to say here that the zero of the "Lake Shore" gauge
is 95 feet lower than the track of the Pacific Railroad at Ogden, and 4,208
feet higher than mean tide. The implied altitude of Ogden, 4,303 feet, is
that accepted by Gannett in his dictionary f)f altitudes.^
As the various measurements employing the water of Great Salt Lake
as a datum were executed on different days and in diff'erent years, it was
necessary to take account of the fluctuations of the lake surface, and this
was done by means of the series of gauge observations already described
(see page 233).
A more important difficulty was encountered in connecting the lines of
leveling with the plane of the f»ld water surface, for it was never ])ossible
to decide just how the mean level of the old water surface was related to a
particular feature of its shore record. At some ])laces the measurement
was made to a cut-terrace, and at others to an eml)ankm('nt, niid wherever
both these were found in juxtaposition and measured, it was ascertained
that the embankment stood higher than any ])art of the cut-terrace. It
was found, moreover, that the diflerence between these twt) features was
'A Dictionary of Altitudes in the Unitod States, compiled by Henry Oannett: Bull. T'. S. Geol.
Survey No. 5. 1884.
ALTITUDE MEASUREMENTS.
365
less in sheltered localities than on coasts facing the open lake, where the
fetch of the waves was great. The inference of tW, phuu! of tlie ^\■at(•r
surface drawn from tlie local shore record wns thus necessaril\- n inatfer of
judgment, and tliis judgment was usually exercised upon llie gniund, wliere
the most .satisfactory consideration could be given to the local conditions.
Despite all precautions, an uncertainty of several feet attaches to each such
determination, and tliis uncertainty is iiu'luded in the estimation of llie
probable errors of the measurements of altitude.
Most of the barometric observations and all the l^arometric computa-
tions were made by Mr. A. L. Webster. He has also combined, unified,
and tabulated all the determinations of altitude, and has prepared a report
upon them which appears (Appendix A) at the end of this volume. For all
matters of detail the critical reader is referred to his report.
DEFORMATION OF THE BONNEVILLE SHORE-LINE.
A summary of the measurements is contained in tables XIII, XIV,
and XV, and their geographical distribution is indicated to the eye in Pis.
XLVI, XLVII and XLVIII. Attention wdll first be directed to the table
and plate which exhibit the measured altitudes of the highest Avater line.
Table XIII. — Height of the BonveviUe Shore-line, at varioiin 2)oi>ils, above Great Salt Lulce {Zero of "Lake
Shore" gauge).
Locality.
1. Sautaqiiiii, south of Utah Lake
2. Leuiiuj;tou, U. S. K. U
3. Milfonl, U.S. R. R
4. Red Rock Vass, north end of Cache Valley
T). Franklin, CJaehe Valley
li. Logan, Caeho Valley
7. Point of the Monntain; 22 niile.s south ol' Salt Lake City
8. Ogden
9. Fort Douglas, near Salt Lake City
10. Tecouia, Nevada
11. Willard, east shore of Great Salt Lake
12. Black Rock, north end of Oquirrh Range
13. Stockton, head of Tooele Valley
14. Kelton Butte, near Onibe Station. C. P. R. R
Height.
Feet.
902 -(- 3
902 -t 5
904 i 10
900 ± 4
940 -I- 3
942 i 4
9.'30 ± 3
980 4-5
980 ±5
981 ±5
98.1 ± 3
1008 ± 3
1014 ±5
1019 ± 3
366
LAKE BONNEVILLE.
Table XUl.—Bcight of Ihe Bonnerille Shore-line, at varioux pohilH, above Great Salt Lake (Zero of " Lake
Sliore" gauge) — Coutiniied.
Locality.
iri. Promontory, 10 miles south of Promontory Rtatlon, C. P. R. R
If). North end of Aqiii range; 12 miles northwest of Grantsville...
17. Two niile.s east of Thermos Spring, Escalante Desert
H. Pavant Hnttc, Sevier Desert
19. Seven miles sontli of Mil ford
20. Four miles south of Thermos Spring, Escalante Desert
21. Seven niiU>s south of Thermos Spring, Escalante Desert
22. Fillmore, east edge of Sevier Desert
23. South Twin Peali, south end of Sevier Desert
24. Kanosh Butte, south end of Sevier Desert
25. North Twin Peak, south end of Sevier Desert
2G. Antelope Spring, Escalante Desert
27. Sulphur Spring, Escalante Desert
28. Pinto Canyon, Piscalaute Desert
29. Shoal Creek Canyon, Escalante Desert
30. Meadow Cieek Canyon, Escalante Desert
Height.
Feet.
10.^0 -t 3
1070 -{- 3
893 ± 2.5
902 J- 15
921 ± 20
921 ± 25
927 i 25
938-1-8
9.39 ± 20
953 -t 15
971 ±20
1008 ± 30
101.-) -J- 25
1175 ± 35
1227 ± 35
1256 ±35
It appears by inspection that the range of ahitude is about 350 feet,
the determination of the amount having an uncertainty of less than 50 feet.
The distribution of altitudes does not follow any simple law, l)ut yet exhil)-
its certain general features. There appear to be two areas in which the
water mark is especially high, the first coinciding approximately with the
central meridian of Great Salt Lake, and the second occupying the Esca-
lante Desei't, especially its southern portion. Along tlie eastern border of
the basin, from the extreme north to the extreme south, there is a general
increase of altitude from east to west. At the south this is continued west-
ward to the limit of the area covered by the observations, ami is greatly
accented. At the north, where the observations have the greatest range in
loiiiritude, the westward rise is rcijhu'cd bcNoiid tlie I'l-oiiiontorv Ivauiic bv
a westward decline. It ap])ears, moreover, that to ;ill tliese general ruU's
there are local exceptions, and that where a rise in a certain direction i.-<
continuously indicated by a series of localities, its rate from point to j)oint
is not unifonu.
DISPLACEMENTS OF BONNEVILLE SHORE-LIN^,.
367
A comparison of the measured heights of shore-hne with the system of
faults in the same region indicates in general that they are not closely
related, and in particular that the faults cannot be appealed to as a suffi-
cient explanation of the displacements of the shoi'e-line. A good illustra-
tion of this is found in the latitude of Salt Lake City, where the height of
the shore-line has been measured on three adjacent parallel ranges. On the
Wasatch it is DSO feet, on the (Jquirrh 1,008 feet, and on the Aqui 1,070
feet. Now each of these ranges has suffered a post-Bonneville faulting at
its western margin, as represented in Fig. 49, and the throw of each fault is
to the west. The eft'ect of these faults, if there were no other diastrophic
V.
A
T
A
si
h
•^ /
\
TOOELE VALLEY
/
,\
JORP A tJ
VA
LLEY
%
=5 5 /
/
t \
o
5 S /
0: \
/
or
V__^
5
v__
i
K 1
h.
?lf
?|
cj
\
Fig. 49.— Generalized cross-profilo of mountains and valleys, illustrating post-Bonneville dia3troi)bic ( hanges. Ver-
tical scale greatly exaggerated. Lower liorizontal lino = level of Great Salt Lake. Dotted line = 1,000 feet above Great
Salt Lake. Y T & = Bonneville shore-line.
changes, would be to lift the Wasatch higher than the Oquirrh, and both
higher than the Aqui, but the shore measurements show the reverse of this.
If we assume that the portion of the earth's crust included between each
pair of the observed faults is rigid, so as to move as a unit without flexure,
then the post-Bonneville changes determined l)v the observations on faults
and shore-lines are correctly represented (except in exaggeration of vertical
scale) in fig. 50, where the base line indicates the level of Great Salt Lake,
Fir;. 50. — Diaj;ran» of po-st-Roiineville tii;istropliic changes. Easo line — level or (tftat Suit I,jiK<^. l*<itt(Ml Hue ~ nrijr
iiinl position of plane <)f Komievillo sliore-liiir. Inclined linea =: present jiosition of same plane. *4 O TT^ positions of
Aqui, Oquirrh and Waaatch Ranges.
the dotted line parallel to it represents the original horizon (»f the Bonneville
sliore-line, assumed to be marked in some way on the orogenic block, and
368 LAKE BONNEVILLE.
the sloping' lines represent the position the sliore-line has assumed by dias-
trophic flianges since tlie Bonneville epoch. Tin- indication is that each
erogenic block is canted to tlu; eastward (riglit), and that eacli block con-
sidered as a whole stands liigher than its eastern neighbor, notwithstanding
its relative depression along- the plane of contact. It' the })henomena of tliis
group of localities were general, we should have an exceedingly interesting
relation between the general deformation of the shore-line and the system
of faults; but they are not general, and we can only say that the principal
diversities of shore-line altitude ap})ear to be independent of, and otten in
spite of, changes by faulting. The changes revealed l)y tlie measurement
of shore-lines affect broad areas, and are essentially epeirogenic, while those
demonstrated by the favdt scarps are definitely associated with mountain
ranges, and are orogenic. The shore-lines are indeed deformed by both sj's-
tems of disturbance, but the epeirogenic are the greater. Just as the Great
Basin is characterized by bi'oad epeirogenic undulations, dividing it into a
series of minor basins, and by relatively narrow mountain corrugations,
Avhicli rest upon the broader undulations like rijjples on the ocean wave, so I
conceive the post-Bonneville epeirogenic displacements to be the greater of
the features represented by the deformation of the shore-lines, and the oro-
genic displacements to cond^ine with them as local details or irregularities,
it would be desirable from this point of view to eliminate the orogenic
factor and study the epirogenic changes by themselves, but our knowledge
of the fault system is too imperfect to permit this, and it will therefore be
assumed, somewhat arbitrarily, that the e])irogenic undulations are smoother
and simpler than the measurements would indicate, the a])])arent iiregidar-
ities Ijciny due to local faultin"' as well as to errors of measurement. ( )n
the basis of tliis assumption isogrammic Hues have been drawn on Plate
XLVI, connecting, so far as possible, points at wliicli the l!oniK\ illc sliorc-
linc has now the same altitude. Tliey art^ drawn at ccpial inti'rvals of 100
feet, and serve to express in another way the general featin-cs of distribu-
tion of altitude described above. If we conceive of the plane of tlie ancient
water surface, both actual and ideally projected through the contiguous
land, as having been deformed by subsequent epeirogenic changes, then
these lines are contours on the deformed surface.
U.S. GEOLOGICAL SURVEY
LAKE BONNE'/ILLE PL.2EVI
111
JuJiim Bien ftCb.lilh
DtawB bv G Thompst
SYNCHRONISM OF BONNEVILLE SBOliB-LINE. 369
It has been tacitly assumed up to tliis point tliat all these measurements
of the Bonneville shore-line relate to the same e|)0('li, or, in other woi-ds, that
the various sections of the highest shore mark in all jiarts of the basin were
formed at the same time; but in view of the demonstrated mutability of the
land surface on which the water marks are traced, this assumption is mani-
festly open to question. It may well have Imppened that at one high stage
of ^yater in the basin the maximum water line was scored upon a land surf;i,ce
in one attitude, and at the following high stage upon the same land surface
in a different attitude, and that the two water lines severally reached their
greatest heights on the land at different points. Tlie highest water line in
one part of the area would then re[)resent one tlood stage and elseAvhere the
other, so that the maxinmm line as a whole would not be synchronous. It
might also happen that during tlie maintenance of one high stage changes
would occur in the relative height of different portions of the land, causing
some parts to emerge and others to become more deeply submerged. This
also would produce a lack of synchronism in the highest shore-line. The
questions arising from these possibilities must in general be difficult of
solution, but in the case of the Bonneville shore-line we fortunately have a
test of wide application. The reader will recall that in the detailed account
of the shore there were described a number of series of bars differing by a
few feet in height, and demonstrating that just previous to the establish-
ment of the outlet the lake surface had undergone a corresponding series of
oscillations. A comparative study of these systems of bars showed that the
oscillations had been essentially the same at all localities, and it is thus
known that throughout the area of their occurrence the shore-line belonjrs
to the same high-water stage. The demonstration applies to the entire
main body of the lake and its principal dependencies, and to the Sevier
body and Preuss Bay, but it does not a.pi)ly to Escalante Bay. Tlie most
southerly points at which the peculiar bar system was observed lie in
latitude 38° 40'. The lack of positive data in the region of the Escalante
Desert is not of great significance, for opj)ortunities for observing this spe-
cial feature are everywhere rare, and there would be no reason for giving
special consideration to that region in this connection, were it not that the
displacements there exhibited are of exceptional magnitude. The crowd-
MON I 24
370
LA. KB BONNEVILLE.
ing together of the contours of deformation in that region suggests tliat the
epeirogenic forces may there hnvc liad a hunger period for the accunudation
of their results, and raises tlie ([uestion whether the Escalante Desert may
not liave received an arm of the lake during its first period of flood, and
then have been so greatly elevated as to remain dry during the period of
the second flood. The only evidence that can be brought to bear upon
this question without new field work is obtained by comparing tlie Escalante
shore record, as to state of preservation and strength, with the records in
other valleys of similar character. Mr. Howell and Mr. Webster, who were
the chief observers of the Escalante shore, both report it as faint and diffi-
cult of determination, and my own observations, limited to a few localities
only, confirm their report. The best region for comparison is Snake Valley,
where, as in the Escalante Desert, the bay was shallow as well as narrow,
and judging from my own observations, the Snake Bay shore record is
notably more conspicuous than that of Escalante Bay.
In view of these considerations the Escalante data will be disregarded
in the subsequent discussion of the deformation of the Bonneville shore.
Table XIV. — Height of the Provo shore-line, at various points, above Great Salt Lake (Zero of ''Lake Shore"
gauge).
Locality.
1. White Mountain spring, e.asl side of Sevier Desert
'2. Franklin, Caclii' Valley
3. Logan, Ciche Valley
4. Point of the Mountain ; 22 miles sonth of Salt Lake City
5. Will.ird, east shore of Gre.it Salt Lake
6. Black Eock, north end of Oquirrh Range
7. Tooele Valley between Tooele .and Stockton
8. Kolton Butte, near Onil)e st.ation, C. P. K. R
9. Promontory, 10 miles south of Promontory station, C. P. R. R
10. North end of Aqni Range; 12 miles northwest of Grantsville .
Height.
Feel.
553 ±
10
5G9 ±
^
577-1-
2
580-1-
3
624 ±
5
640 ±
4
(i40 -t
5
r>(i3 -t
3
672 ±
3
679 ±
3
ESCALANTE BAY. 371
DEFORMATION OF THE PROVO SHORE-LINE.
We will now turn to the consideration of Table XIV and PI. XLVII,
which record in their several ways the various determinations of the heig'ht
of the Provo shore-line. The special criterion by which the identity and
synchronism of the Bonneville shore-line were established throughout the
greater part of the liasin cannot be applied in the case of the Provo.
Where the embankments successively formed during Provo time are sepa-
rated from one another so as to be independently measured, they exhibit
differences of height, but these diiferences are neither uniform nor constant
at the various localities where they were observed. The conclusion has
already been reached (page 133) that there were changes of relative height
while the wave record was being made. Nevertheless, it was always easy
to recognize the Provo shore-line and discriminate it from others by reason
of the exceptional magnitude of the wave work accomplished at that level.
The cut terraces are broader than any other within the basin, and the
embankments are larger. At most points it is impossible to determine from
the features of the shore what was the local history of oscillation during the
persistence of the outlet, for the later work of the waves has effectually
obliterated the earlier. It is highly probable that those of its features to
which measurement was extended represent the final portion of the long
period during which the water stood at approximately the same height.
The number of measurements is smaller than in the case of the Bonne-
ville shore-line, only 10 having been secured; but these are so much more
harmonious that it was found possible to draw a system of smooth contours
representing intervals of 25 feet only. A comparison of Pis. XLVI and
XLVII shows at a glance that these correspond in position and arrange-
ment with the contours adjusted to the Boinieville data in the same area.
The area of maximum elevation indicated by them lies over the western
portion of Great Salt Lake. There is a descent thence to the east, and
more gently to the southwest and south, while a single station indicates
descent to the northwest also.
372
LAKE BONNEVILLE.
Table XV. — Difference in altitude of the Bonneville and I'rovo shore-lines at various points.
Locality.
Prciiss valley, South series of embankments
Preuss valley, Middle series of embankments ,
Kelton Butte, near Ombe Station, C. P. R. R
Black Rock, north end of Oquirrh Range
Willard, east shore of Great Salt Lake
Snowsville, north edge of Great Salt Lake Desert
Logan, Cache Valley
Point of the Mountain, 22 miles south of Salt Lake City
Franklin, Cache Valley
Promontory, 10 miles south of Promontory Station, C. P. R. R
Tooelo Valley between Tooele and Stockton
Tooelo Valley between Tooele and Grantsville
Wellsville, Cache Valley
Fish Spring, south edge of Great Salt Lake Desert
Fillmore, east edge of Sevier Desert
North end of Aqui Range; 12 miles northwest of Grantsville
Cup Butte, Old River Bed
Suowplow, Old River Bed
Terrace Mts., 8 miles southeast of Matlin Station, C. P. R. R
Dove Creek, between Matlin and Ombe, C. P. R. R
Height.
Feet.
311 ±
345±
3o6-|-
360 -J-
361 i
360-1-
^r,r, ±
370 -t
371 -t
374 J-
374-1-
380 -t
382 ±
382 ±
385-1-
389 i
392 i
397 -t
411-1-
413 ±
DEFORMATION DURING THE PROVO EPOCH.
Table XV and PI. XLVIII show the measured differences in aUitude
of the Bonneville and Provo shore-lines at various points. The localities at
which these differences were measured coincide partly with localities of the
two ])receding tables, but are also in part independent; for it was sometimes
found possible to make the differential measurement where tlie lack of an
available datum point prevented the reference of either to the level of
Great Salt Lake.
The range of variation is not large, and whatever order mi\\ charac-
terize them is so far concealed by irregularities that it was found impossible
to classify them by any system of smootli contours. Ikit, as will j)resently
appear, when they are classified with reference to the contours of the IJon-
neville and Provo .shore-lines, thev betray a certain amount of harmonv.
It will be recalled that when the lake attain<Ml its maxiniuni height and
outflowed, the water was discharged witii great raj)idity down to the level
U S. GEOLOGICAL SUF^/EY
L/a<.E 'BO^U'IE'.ILI.K PI ,. XLVJJ
112°
iir
- a"
MAP OF
LAKE BONNEVILLE
shoT.\'inq
THK DEP^OR^L\TION
OF THE
PROVO SHORE Li:s'E
thl; i^(isiti(-)N of cheat s.\lt lake
on tt.s pi.mn
42°
Julius Bien iGi.lith
Drawn by G Thomps.
us. GEOLOGICAL SURVEY
LAKE BONNEVILLE PL. XLViR
LAKE BONNEVILLE
showing
local variations of the
VPJRTICAL INTERVAL
between iKe
BONNEVILLE AND PROVO
SHORELINES
red Figures indicate
ences of altitude in feet
j Miles.
Julms Hieii ftCo.hih
Dravrn hv C Tliumpsoti
DISPLACEMENTS OF THE PKOVO EPOUH, 373
of the Provo shore, at which level the lake stood for a relatively long time.
This time may have been continuous or may have been more or less inter-
rupted by the temporary retreat of the Avater to lower levels. Including
such interruptions, if any occurred, it has been called the Provo epoch.
The table and map of differences between the Bonneville and Provo shore-
lines represent the changes of altitude occurring in Provo time, or from the
end of the epoch of the Bonneville shore-line to the end of the Provo epoch.
The diiferences of level of the Provo shore-line represent changes wrought
since the end of the Provo epoch, and those of the Bonneville shore-line
changes since the beginning of the epoch of outflow.
POSTULATE AS TO CAUSE OF DEFORMATION.
The area of maximum elevation, as indicated by these data from the
Bonneville and Provo shore-lines, coincides with the middle portion of the
main body of Lake Bonneville; and this coincidence suggests the hypothesis
that the disappearance of the lake and the epeirogenic rise of the center of
its basin stand in the relation of cause and effect. In the ensuing discussion
this relation will be postulated, though it must be clearly understood that
the available data do not demonstrate it, but merely endow it with a certain
degree of probability; and since a somewhat elaborate structui-e will be
founded upon it, it is especially desirable that the weakness as well as the
strength of the postulate be clearly perceived
The postulate is in some sense graphically expressed by PI. L, where
the contour lines of the preceding plates are so modified as to make closed
curves repi'esenting a dome-like figure of deformation, slightly elongated in
the direction of the axis of the lake. The data used in the construction of
this system of lines are selected from the measurements of the Bonneville
shore-line, excluding all that depend upon Ijarometric work — a principle of
selection which omits all measurements with high probable error, as well as
tliose made in the Escalante Desert, which are independently questionable.
The first consideration favoring the postulate is the one just mentioned,
that, so far as trustworthy measurements indicate, the area of maximum
uplift coincides with the center of the principal area of deep water in the
old lake.
374
LAKE BONNEVILLE.
A second favorable consideration arises from a comparison of the clianges
occurring severally during the Provo epoch and since the Provo epoch a\ ith
the total changes since the formation of the Bonneville shore-line. To make
this comparison, the various measurements were classified with reference to
areas marked out by the hypothetic contours. In Table XVI, the colunm
of figures at the right contains measurements of the height of each shore-
line and of their difference, so far as these were measured within the area
circumscribed by the 1050-foot contour. The next column at the left con-
tains the measurements made at localities falling within the area limited on
one side by that contour and on the other by the 1000-foot contour; and
so for the remaining two columns.
Table XVI. — Comparison of post-BonneviUe, post-Provo and Proi'o Deformations (fii/nres yire feet).
Areas between contours on Plate L
900
to
9.''>0
950
to
1000
1000
to
1050
1 Above
1050
Determinations of Bonneville shore-liue above
Great Salt Lake .,
(- 902
902
904
906
940
942
9.'j0
965
980
981
1008
1014
1019
1050
1070
Mean . ........ .... ..
916
969
1023
1070
Determiuations of Prove shore-line
Mean .-
553
569
577
580
624
640
640
663
672
679
566
602
654
679
Determinations of difference between Bonne-
ville and Prove shore-lines
Mean ...
- :J41
345
365
- 371
385
361
365
370
382
382
392
397
356
360
374
374
380
411
413
389
361
378
381
389
By arranging the determinations in this way and then taking means,
it was hoped to eliminate so much of the in-egularity due to orogenic dis-
US .GEOLOGICAL SURVEY
LAKE BONNEVILLE ?L:ZLI2
US'
113°
n2°
xa."
Julius Bien it Co. lith
Druwu bv C Thompsc
U. S. GEOLOGICAL SURVEY
LAKE BONNEVILLE PL. L
SCALE
ILES
THEORETIC CURVES OF POST-BONNEVILLE DEFORMATION.
DESICCATION AND UPLIFT. 375
placement and to errors of measurement as to render the data fairly com-
parable. The measurements of the Bonneville shore-line having been used
as a basis for th-awing the contours, their means, as a matter of course,
constitute a series; and it was anticipated that the Provo determinations,
having given rise on PI. XLVII to very similar contours, would likewise
furnish, as they do, a progressive series of means; but a similar corre-
spondence could not have been confidently predicted for the observations
of difference in altitude of the two shores, for these are so irregular in detail
that representative contours could not be drawn. Nevertheless, their means
as thus classified fall into line with remarkable regularity. It appears to
be a legitimate inference that the epeirogenic deformation occurring during
the Provo epoch was identical in locus and general character with that
occurring subsequently, and with the total deformation of which it is a part;
and this accords with the postulate, for if the withdrawal of the entire mass
of water produced the quaquaversal uparcliing of the basin, then the par-
tial emptying of the basin by the draining off through the outlet of a layer
of water 375 feet deep should produce a similar uparcliing, differing only
in amount.
Opposed to the postulate, we have the general fact that the Great
Basin appears to have been characterized by epeirogenic movements, varied
in character, through Tertiary and Pleistocene time, and that as these move-
ments successively created and destroyed lake basins, they must be sup-
posed to have generally originated in a different way. It is therefore pos-
sible that the coincidence in time and place of the uplift under consideration
with the disappearance of Lake Bonneville is a coincidence merely.
A second and very serious element of weakness in the postulate
inheres in the fact that the observations are mainly confined to the eastern
lialf of the basin. Only two points of observation lie west of the max-
imum area, and only one measurement was made in the extreme western
portion of the basin. The area well covered by points of determination is
at most not more than two-thirds of the entire area to which the postulate
is applied.
These considerations pro and con hardly admit of explicit summation.
The predilections of each geological reader will determine the relative
376 LAKE BONNEVILLE.
weight he asisigns to them, and his cniisoqneiit confidence or lack of confi-
dence in the conclusions which follow.
There are at least three ways in wliicli the removal of the water may
have given rise to the observed variation of altitudes. First, the geoid may
have been locally deformed by a change in the local attraction; second,
the surface of the laud may have been deformed by local expansion due to
the post-Bonne ville change of climate; third, the earth itself may have been
locally deformed in consequence of the removal of the weight of the water.
These three hypotheses will be considered in order; and it will be found
advantageous to inquire Avith reference to each how the deformation it is
competent to produce compares in amount with the observed defoniintion.
The maximum measure of the observed deformation is 1070 — !M)2r= l(>s
feet; but as this may, and probably does, involve local orogenic displace-
ments, it will be better to use for the present purpose a measure obtained
by comparing a number of the highest measurements collectively with a
number of the lowest. The mean of the five observations of height falling
within the 1000-foot contour is 1032 feet. The mean of the four lowest
determinations is 903 feet, and their difference, 121) feet, will be compared
with the various amounts inferable from the three hypothetic causes.
HYPOTHESIS OF GEOIDAL DEFORMATION.
The siu'face of a body of standing water is level, but is not plane.
Being a part of the surface of the earth, it is ai)proximately ellipsoidal. If
there were no inequalities of surface, and the density of the earth were uni-
form throughout, or varied only in accoi'dance with certain laws, a level
surface carried completely around the globe would be a perfect ellii)soid.
The actual inequalities of surface and irregularities of density produce local
irregularities of attraction and corresponding irregularities of the level sur-
face. To distinguish the deformed level surface from the s])heroid to which
it approximates it is called the "gcoiil". Any change in tlie superficial dis-
tribution of matter modifies tlie geoid, and tlie i-einoval ot the lake water
from the Bimneville Basin was such a change. The effect of refilling the
basin would be to increase the local attraction and locally uparch the geoidal
DEFOKMATION OF PLANE OP KEFEKENCE. 377
surface; its emptying- unquestionably tended to flatten the geoidal surface.
Assuming the configiu-ation of the country unclaanged, the Bonneville sur-
fiice was more sharply convex than the Salt Lake surface, and the engineer's
level should now find the Bonneville shore-line higher on central islands
than on peripheral slopes. The theoretic change corresponds in kind with
the observed; does it agree in amount? My mathematical resources not
being adequate to this question, it was submitted to my colleague, Mr. R.
S. Woodward, who gave it full consideration. It happened that tlie cognate
problem of the deformation of the geoid by a continental ice mass was sub-
mitted to him at about the same time by Dr. T. C Chamberlin, and he
was thus led to a comprehensive discussion of the general subject to which
the special problems belong. In the application of his formulfe to the
present case no account was taken of topographic details, but the mass of
water in the main body of Lake Bonneville was assumed to have the form
of a circular lens two degrees (138 miles) in diameter with a maximum
depth of 1000 feet. It was found that the maximum de^iression of the
geoidal surface referable to the subti'action of such a mass is 2.01 feet, an
amount too small to be considered in comparison with the observed deforma-
tion of 129 feet. The phenomena are therefore not to be explained as
changes in the plane of reference, but must be referred to changes in the
relative altitude of portions of the basin.
The reader will hud an abstract of Mr. Woodward's treatment of the
problem in Appendix B.
HYPOTHESIS OF EXPANSION FROM WARMING.
The second hypothesis involves considei'ations of temperature. The
temperature of the earth's crust at the surface is identical with the mean
annual temperature of the contiguous fluid, air or water, and at all subter-
ranean points it is warmer, the change of temperature with depth being
gradual. Every change of climate prcxluces a corresponding change in the
sui-face temperature of the crust, and this change is slowly propagated down-
ward. When the Bonneville Basin was full of water, there can be little
question that the surface temperature was lower than at present, and it is
possible that the corresponding diff'erence between the temperatures of the
378 LAKE BONNEVILLE.
adjoiniiig laud, then and now, has not been equal in amount, in which case
the i)ost-Bouneville warming of the crust beneath the lake area has been
greater than the coincident warming of the crust underlying contiguous
areas. Rise of temperature carries with it expansion, and the hypothesis is
that such differential expansion pniducedthe observed differential altitudes.
( )ur (piantitative data are here less precise than in the case of the preceding
hypothesis, but it is not difficult to assign to them reasonable limiting values,
so as to obtain a practical test of the hypothesis. The mean annual tempera-
ture at Salt Lake City is 51° F., and this may be assumed for the entire basin.
Its ancient climate was somewhat colder, but the moderate development of
glaciers permits us to entertain the assumj)tion that the difference was small.
The lake, as we know from its wave wox-k, was not frozen, and as it had
great depth, we are assured by the analogy of modern examples that its
bottom temperature was that of water of maximum density, about 39°. The
surface temperature of the crust in the lacustral area was therefore 12
degrees lower than now. If we assume that the surface temperature of the
surrounding land was only two degrees lower than now, we are certain to
underestimate the climatic change, and thus allow a maximum or limitinsf
difference between the crustal changes under the old lake and under the
old land. The problem then takes the form: What uplift can be referred
to the expansion of the upper portion of the earth's crust consequent on a
superficial rise of temperature of 10 degrees occurring at the close of the
Bonneville epoch. The remaining constants necessary for its solution are
obtained by assuming the coefficient of expansion of the rock involved to
])e 0.000006 for each degree, by adopting Sir William Thomson's coefficient
of dift'usion of heat in the earth, and by assigning to post-Bonneville time a
duration of 100,000 years, an estimate intentionally large. For the com-
putation of the vertical rise of the basin from these numerical data I am
indebted once more to Mr. Woodward, who has recently re\'iewed the sub-
ject of subterranean temperatures from the mathematical side. His result
(see Appendix C) is 1.28 feet, an amount quite too small for om- considera-
tion in this connection.
DEFORMATION^ OP EARTH'S CRUST. 379
HYPOTHESIS OF TERRESTRIAL DEFORMATION BY LOADING AND UNLOADING.
The third hypothesis exphiius the pheiiouieiui Ijy assuming that when
the BonneviHe Basin was tiUed with water, the earth yiekled to the weig-ht
of the water, permitting a (h^pressiou of the headed area, and tliat when the
water was afterward remo\'ed, tliere was a corresponding rise of the unhjaded
area. The manner of yiekhng, the amount of vertical change, and tlie
figure of deformation all depend on the constitution of the earth, and as
that constitution is unknown, it is necessary to make assumptions regarding
it iu order to discuss the quantitative sufficiency of the hypothesis. If the
earth were perfectly rigid, the removal of the Bonneville load would not
affect its form; if the earth were completely liquid, the removal of the load
would cause the load to be replaced by the uprising of an equal weight of
matter. Neither of these extreme conceptions can be entertained, for the
visible portion of the eartli is neither liquid nor perfectly rigid, but between
them is room for an infinite variety of special assumptions under each of
which some deformation of the basin must be assigned to the unloading.
In order to learn the order of magnitude of the greatest possible
deformation, let us assume for a moment that the earth is constituted by a
thin solid crust resting upon a liquid substratum, and that the rigidity of
this crust is very small in comparison with the stresses applied to it by the
removal of the water from the Bonneville Basin. The floor of the basin
will then rise under the action of these stresses in some sort of arch,
whose interior will be filled by liquid matter derived from surrounding-
regions. The weight of tlie liquid matter thus introduced will lie approxi-
mately equal to the weight of the water removed by evaporation, and the
height of the crustal arch will be related to the depth of tlie water in
(approximately) the inverse ratio of the densities of the two liquids. Tlie
liquid rock may be assumed to agree in density with the average density
of visible rocks at the surface, 2.75, and this gives us as the heiglit of the
I'esulting arch the quotient of 1000 feet by 2.75, or 364 feet. This is the
height attainable by the arch on the supposition that the strength of the
crust is a vanishing quantity, and it is the superior limit of all possible
values for the height of the arch. With the strength a vanishing quantity,
380 LAKE BONNEVILLE.
the vertical stresses due to unloading are equilibrated by vei'tical stresses
due to gravitation, and the height of arch is 304 ft ; with the strength finite,
the stresses of unloading are equilibrated partly l)y stresses of gravitation
and partly by elastic strains, and the height of arch is a function of tlie
stresses of gravitation. While the natvire of this function is more conq)lcx
than that of simple proportion, it is fair to infer from a comparison of tlic
observed height of the arch of deformation, 129 ft., with tlie limiting heiglit,
3G4 ft., that under this hypothesis the stresses from unloading arc; satisiicd
chiefly by elastic strains and secondarily by gravitational stresses.' Tluit
this implies great strength of crust Ijecomes apparent when the magnitude
of the load removed and the width of the affected area are considered. For
the sake of illustration, assume that 129 feet of uplift satisfy tlie stres.ses
due to 355 feet (129 X 2.75) of the removed water; there remain the stresses
due to 645 feet to be satisfied by strains in the crust. Call the basin floor
a beam, 120 miles long, supported at the ends, and sustained throughout
by flotation so far as its own weight is concerned. Call the modulus of
rupture of its material 3,000 pounds to the stpxare inch, and introduce no
fiictor of safety. Consider the beam to be suljjected to upward stress 1)}'
the removal of 645 feet of water from its entire upper surface, and compute
by the engineer's formula the depth of beam necessary to stand the strain.
It is about 32 miles.- The illustration is a rude one, because the floor of
the basin, being attached all about its periphery, is stronger than a beam
supported only at the ends; because a crust graduating into a li(piid
beneath is weaker than a homogeneous crust; because the modulus of
• If we postulate a tliick crust it is proper to postulate also that the matter flowing In beneath
the dome has a greater density than superficial rock. Wilh the density 3.5 — an rxtronie assumption —
tlie limiting height of arch is 280 feet.
-The engineers' formula is
where W is the breaking stress in pounds, the stress being evenly distributed over the upper surface
of the beam; R Is the modulus of rupturi' of the material in poumls pir scinare inch ; b is the lireadlh
of the beam, (fits depth and I its kiigtli. In the case under cunsideratlon W =D(j/h, in which I) is the
depth, in feet, of water removed, and (/ is the weight, in pounds, of a column of water one inch scjuaro
and one foot in height. Substituting this value for W in the formula, transposing and reducing, wo
obtain
2 = .434 pound. Making 1 = 120 miles, D = G45 feet aud U = 3000 pounds, we find d = M.7 miles.
UiSTLOADING AND UPAEOHING. 381
viscous distortion is less — possibly far less — tlian the modulus of rupture;
and for other reasons; l)ut it nevertheless assists the iniaginatiou in i-ealiz-
ing the relation of bulk to strength. Witli its aid I trust tlie reader \\ ill
follow me in tlic conclusion that the hypothesis of local deformation of tlic
earth l)y local unloading aifords results of the same order of magnitude as
the observed distortion of the plane of the Bonneville shore, and is quanti-
tatively adequate.
The first and second hypotheses having been foinid quantitatively in-
adequate, the third is the only one meriting further discussion. A thoi-ongli
treatment is on the one hand highly desirable and on the other beset
with difficulties. It is desirable because it pi'oraises to throw some light on
the condition of the interior of the earth; a solid earth would not yield the
same deformation as an earth partly liquid; a highly rigid earth would be-
have differently from one of feebler rigidity. It is difficult because it must
deal with magnitudes and pressures far beyond the field of experimenta-
tion, and can be accomplished only Ijy the aid of comprehensive mathe-
matical analysis. It requires an analytic theory of the strains set up by a
stress applied locally to the surface of the earth and of the resulting defor-
mation, and this theory must be so general as to include divers assumptions
as to the variation of elasticity with depth from the surface, and as to the
relation of the strains to the limits of elasticity.' The evolution of such a
theory is beyond my power, but in the belief that it is worthy of the attention
of the mathematician and physicist, I will endeavor to state the problem.
Assume, first, that the rigidity of the earth is uniform throughout, or
at least for some hundreds of miles from the surface, its modulus of elas-
ticity being that of granite, fi)r example. Then conceive the application to
the surface of a lenticulai- Ixxly of water etpiivalent to Lake Boinic\il]e,
'As defined by Sir Williani Thomson, " Elasticity of matter is that property in virtim of wbith a
body requires force to chan};e its bulk or shape, and requires a coritiimoiis apiillciitioii of tlio force to
maintain the chauj^e, and .spriuss baclc when tlic force is removed, and if left at rest without the force,
does not remain at rest except in its ))rovions bulk and shape." Elasticity of bnlk and elaslicity of
shape are distinct properties, which coexist iu solids, but not in liqnids. Kiii;iility is synonymous with
elasticity of shape. Solids differ iu regard to rigidity in two ways. They have dilfcrcnt moduli of
ri^dity and differeut limits of rigidity or elasticity. The niodulns of rigidity depends upon the
.stress necessary to jiroduce a unit of deformation, or upon the deformation produced by a unit of stress.
The limit of rigidity is reached when the force applied is so great that after its removal the solid does
not return to its original shape.
382 LAKE BONNEVILLE.
but spnmetric. To imagine the result, it is necessary to divest the mind
of the ideas of brittleness and great strength ordinarih- associated with
granite and other massive rocks. Brittleness is a, surface phenomenon
only; at a depth of a few thousand feet, or at most a few miles, the tend-
ency to fracture is effectively opposed by ])ressure. Strength is condi-
tioned by magnitude, and in relation to magnitude it is a diininishing func-
tion. Structures of the same form and material are not strong in pro])or-
tion to their size but are relatively weaker as they are larger until hnally
they can not sustain their own weight. In a general way strength increases
with the square of the linear dimension; weight and otlicr luads increase
M itli tlie cube. Giving due weight to these considerations, it is not improper
to compare the earth when loaded by the water of Lake Bonneville with a
bowl of jelly upon wliich a coin has been laid. The results in either case
are, tirst, the depression of the area beneath the load, second, the formation
of an annular ridge about it, and third, the production of strains within the
mass. Conversely, the removal of the water of Lake Bonneville would pro-
duce an uprising of the central area of the basin and an annular depression
all about, and would either relieve the strains previoitsly produced by the
addition of the water, or, if these strains had been otherwise relieved, would
set up a new system with opposite signs. It is easy to understand from the
homologous phenomena of jellies that the precise figure of tlie superficial
deformation Avould de])end on the modulus of elasticity of the earth material.
With a low elasticity the central arch would be high; with a high elasticity
the figure of deformation would be comparatively low.
There are two elements of complexity that inhere in the subject. In
the first place, the deformation of the earth is resisted not only l)y the elas-
ticit}' of the material but l)v gravitation, which always tends to give the
siu'face the normal configuration of the gcoid. In the second place, the
stresses created l)v the removal of the Homicvillc water wnuld have certain
effects through the property of bulk elasticitv as well as that of shape elas-
ticity. It is not improbaljle that a suitable discussion of tlie subject would
demonstrate that the deformations ascribable to ])ulk elasticity are too small
for consideration in connection with those referable to shape elasticity, l)ut
to this extent at least thev Avould need to be considered.
UNLOADING AND U PARCHING. 383
Add now a third element of complexity, by assuming tliat tlie strains
set lip by the removal of the water are not entirely within the limit of elas-
ticity of the material. Wherever they exceed the elastic limit, change of
another sort occurs, probably not fracture, as in laboratory experiments on
the limits of elasticity, but flow — such flow as Tresca's experiments have
demonstrated for colloids.^ The plastic yielding of the rock in the region
of greatest strains woidd cause a partial redistribution of strains in adja-
cent regions, and would correspondingly modity the figure of deformation.
The height of the central arch would be increased.
Now add yet one other element of complexity, by assuming that the
modulus of shape elasticity and the limit of shape elasticity vary (simulta-
neously and harmoniously) in accordance with some law involving the dis-
tance from the surface. They niay increase from the surface down^^^ard,
or they may decrease from the surface downward, and in the latter case
liquidity will at some depth be reached. The actual deformation should be
comparatively low if the elasticity increases downward, and comparatively
high if the elasticity diminishes downward.
The application of an analytic theory of these relations could yield the
best results only with a better determination than we now have of the elastici-
ties of rocks, and with a better determination of the figure of the deforma-
tion of the Bonneville Basin; but even with the imperfect data at liand it
might establish a presumption for or against the existence of a liquid sub-
stratvim beneath the rigid crust, and if the mathematical difficulties were
surmounted, there can be little question that the observational data would
be supplied, for their procurement is opposed by little beside their expense.
Without waiting for the mathematician, we may conclude in a general
way that the floor of the Bonneville area arched upward when the load of
water was removed, and that this deformation was permitted by the feeble
elasticity or the imperfect elasticity, or l)oth, of the portion of the earth
affected; the conclusion being qualified l)y whatever weakness inheres in
the postulate that the coincidence in time and place of crust unloading and
crust deformation is not fortuitous
>M6m de I'Inst. Savants strangers, vol. 18, 186S.
384 LAKE BONNEVILLE.
EVIDENCE FROM THE POSITION OF GREAT SALT LAKE.
In an earlier chapter attention has been called to the fact that in the
central portion of the basin of the main body of Lake Bonneville mountain
ridges are so nearly buried by lacustrine sediments that only their summits
remain visible, jutting forth from the plain after the manner of islands.
The amount of sedimentation implied is great, and its magnitude is like-
wise indicated by the general evenness of the plain. Wherever the writer
has crossed a portion of this plain, he has found himself, after leaving the
foot slope of the contiguous mountains, upon a plnya Hoor with no discern-
ible inclination, and nearly bare of vegetation. The saltness of tlie soil
testifies that water does not flow across it, but rather stands upon it and
evaporates. Another evidence of the general evenness of surface is the
shallowness of Great Salt Lake, which has a mean depth of less than IT)
feet.
At the present time the principal contrilnition of debris toward the iill-
ino- of the basin comes from the east. On the coast of Great Salt Lake
deltas have been observed only at the mouths of the Jordan, the Weber,
and the Bear, all rising in the Wasatch and Uinta Mountains and entering
the lake on the eastern side. The western coast shows capes only where
rocky hills stand near, and bays are found where it receives the intermit-
tent drainage of the surrounding valleys. In Bonneville times the same
contrast existed. The deltas of the old lake are found almost exclusively
where it received streanis from the east, namely, the rivers just mentioned,
their principal tributaries, which then entered the lake directly, and the
Sevier River. No delta terraces were observed about the nortliern, west-
ern, and southern margins, unless possibly in the Escalante Desert.
If this deposition, so great in amount, iind dcrivccl so largely from tlie
east, were the only factor concerned in the dctcnniHatioii of the configura-
tion of tlie desert floor, that floor would be a gently-sloping jjlain, with its
higher margin at the east and its lower at the west, and Great Salt Lake
would lie at tlu^ base of the Gosiute Mountains instead of the Wasatch.
The easterly position of the lake is unquestionnbly due to crustal move-
ment, either orogenic or epeirogenic. (See PI. XLVIl.)
ECCENTRICITY OF GREAT SALT LAKE. 385
Let us first consider tlie possibility of an erogenic cause. The most
conspicuous recent orogenic change in the region is that shown by the fault
scarps at the base of the Wasatch Range. These scarps show differential
movement, either ascent of the mountain or descent of the valley, or both.
The great size of the mountain range, as argued on an earlier page, assures
us that a rising of the range is at least a part of the displacement, but is
not opposed to the idea that the sinking of the valley is a correlative and
perhaps equal part. It is consistent with this idea that the water of Great
Salt Lake between the Bear and Weber deltas, and again between the
Weber and Jordan deltas, approaches within about a mile of tlie great
fault at the mountain base.
Epeirogenic causes may be considered from two points of view: first,
as belonging to a system of changes correlated with the emptying of the
basin by evaporation; second, as belonging to the more general system of
changes to which the basin, as such, may be ascribed. Taking the first
point of view, we have a post-Bonneville rising of the central area amount-
ing to more than 100 feet, and it is conceivable that this has divided the
plain into two basins, of which the lake occupies one, while the other con-
tains only occasional playa lakes, such as the scant rainfall of the tributary
regions is able to produce. Too little is known of the configuration of the
desert west of the lake to determine whether it is partitioned off by a bar-
rier of such sort, or is in time of great rainfall tributary to Great Salt Lake.
But there are other reasons why the hypothesis can not be seriously enter-
tained. In the first place, the area of maximum uplift, so far as our meas-
urements determine it, coincides with the western portion of the lake
instead of with the line of low ridges beyond it. The old shore-line is
higher on Promontory Ridge than on the Terrace Mountains to the west-
ward.
It must also be borne in mind that the present condition of the Ijasin
as affected by climate is substantially identical with the [)re-Bonneville
condition, and the arid phase was of long continuance before the Bonne-
ville flood. Whatever central elevation is recorded by the surviving shore-
line is merely the correlative of central depression during the lake period,
and to assume the post-Bonneville uplifting of the plain into a barrier ade-
MON I 25
386 LAKE BONNEVILLE.
(piate to contain the lake is to assume that during the existence of tlie lake
the central depression was filled by sediments so as to pi-oduce a lake bot-
tom almost absolutely level. From wliat we know by observation of the
slopes on which the Bonne\'ille sediments were able to lie, we can not
believe that this was accomplished, but rather that throughout the deeper
portion of the lake there was an equable deposition over gentle slopes, the
depth of deposit increasing rather toward the source of the material at the
east than toward the center of the lake. It is pn)l)iible that post-Bouneville
changes in the configuration of the plain, so far as they have depended epei-
rogenically on the removal of the water, have been the simple converse of
changes due to the previous imposition of the water, and have practically
restored the preexisting condition.
Turning to epeirogenic considerations of a more general nature, we
see that the Bonneville Basin is a region of depression, surrounded on the
south, west and north by regions of somewhat greater elevation, and on the
east by a tract whose mean altitude is several thousand feet higher— an
irregular plateau, along the edge of whit-h the Wasatch Range stands as a
parapet. The forces which produced this bashi and the plateau to tlie east
of it are of necessity independent of the loading and unloading of the basin,
and of a more general nature. Whatever they may be, it is not irrational
to appeal to them as the cause of the local depression containing Great Salt
Lake and to regard that depression as a result of the mere continuance,
with possibly greater localization, of the process which created the larger
basin.
Whether, then, we regard the peculiar position of the lake as a result
of orogenic or of epeirogenic dis])lacement, we are comijelled to forego tlie
assignment, even tentatively, of a special hypotliesis as to its causr. I*ci'-
haps tlie most valuable cont'lusiou to be drawn is tliat, as drposition witliiii
tlie liasin, during Imiiiid and arid phases of climate alike, lias (•(Hitiiiiially
tended to build the eastern lialf of the plain liiglicr tliaii the western, and.
as this tendency has continued to the present time, the sul)sidence opposing
and thwarting it has likewise continued to a late epoch and is probably still
in progress.
COROLLARY. 387
THE STRENGTH OF THE EARTH.
The writer has been led by the discussion of these phenomena to a
conception of the rigidity or strength of the earth, more definite than he
had previously entertained. It would not be proper to call this conception
a conclusion from the data here presented, or a result to which they rigor-
ously and necessarily lead. It is rather a working hypothesis suggested
by the study of Lake Bonneville.
If the earth possessed no rigidity, its materials would arrange them-
selves in accordance with the laws of hydrostatic equilibrium. The matter
specifically heaviest would assume the lowest position, and there would be
a gradation upward to the matter specifically lightest, which would consti-
tute the entire surface. The surface would be regularly ellipsoidal, and
would be completely covered by the ocean. Elevations and depressions,
mountains and valleys, continents and ocean basins, are rendered possible
by the property of rigidity, but the phenomena of diastrophism, and espe-
cially those of plication, show that this rigidity has its limits, and the
phenomena of volcanism demonsti-ate that its distribution is not uniform.
It has been computed by Darwin' that if the earth were homogeneous
throughout, the stress differences occasioned by the weight of continents
would be as great as those necessary to crush granite. The stress differ-
ence necessary to produce viscous flow in granite and allied rocks is not
known, but if different from the crushing stress, it is less; and Darwin's
discussion therefore tends to show that the earth, if homogeneous, would
require a strength equal to or greater than that of granite. Tliat the earth
is not homogeneous as regards density (and does not consist of symmetric
homogeneous shells) is shown l)y the massing of land ;ireas in one hemis-
phere; and the hypothesis that the crust has low density beneath continents
and high density beneath oceans is sustained by observations on the local
direction and local force of gravitation at various points.- The general
proposition, tacitly postulated by Babbage and Herschel, advocated more
' On the stresses caused in the interior of the earth hy the weight of continents and nioiiutains,
by G. H. Darwin. Phil. Trans. Royal Soc, pt. 1, 1882.
2 On the argument from geodetic station errors see John H. Pratt, Figure of the Earth, p. 201.
On the argument from pendulum observations see H. Faye iu Revue scientifniue for Feb- 20 and
March 27, 188G.
388 LAKE ];ONNEVILLK.
recently by Dutton and Fisher, and entertained ])y most modem writers,
is that the radial elements of the sphere have the same weight on all sides,
the product of the height of each unit colunui into its mean density being
everywhere the same. With such a distribution of densities the stresses
and strains resulting from the existence of continental elevations do not
disappear, but they are less than those derived by Darwin on th^ hyi)oth-
sis of homogeneity. How much less has not been shoAvn, but it is fair to
say that, so far as the evidence from continents is concerned, the (juestion
of the degree of rigidity of the earth's nucleus is still an open one.
If a weight l)e added to a limited portion of the surface of the globe,
there will result a system of strains beneath and aljout the area, and a
defonnation of the surface accordant witli the system of strains. If the
weight is small, and if the effect is not complicated by preexistent strains,
the resulting strains will at every point fall within the limit of elasticity of
the material, and the deformation will be small. If the weight is sufficiently
large, the resulting strains will in some places exceed the limit of elasticity,
and other consequences will follow. Among these, rupture and faulting
may in special cases be included, but the ordinary and predominant res\dt
will be viscous flow. The viscous flow will consume time, and when it lias
ceased, there Avill remain a system of elastic strains. Beyond the elastic
limits, the laws of change for loading the surface of the earth (and similarly
for unloading) are quasi-hydi'ostatic.
The point on which the Bonneville jdienomena appear to throw light
is the magnitude of the load necessary to overpower rigidit}-. The })lie-
nomena of faulting at the base of the Wasatch, whether considered liy
themselves or in connection with the filling of the adjacent valley ^^ itli
water and its subsequent emptying, appear to my mind best accordiint with
the idea that the Wasatch Range and the paralh'l ranges lying west of it are
not sustained at their existing heights above the adjacent plains and valleys
by reason of the inferior specific density of their masses and of the under-
lying portions of the crust, but chiefly and perhaps entirely in virtue of the
rigidity or strength of the crust. The phenomena of deformntion of the
Boimeville shore-line accord best with the idea that the imi)osition of the
Bjnneville load of water and its subsequent i-emoval strained the subjacent
MEASURE OF RIGIDITY. 389
portions of the crust beyond the elastic limit, the stresses due to tlie load-
ing- and unloading- being- partly equilibrated by crustal strains, and partly
relieved by crustal flow and a resulting redistribution of the stresses due to
gravitation. It is indicated that the limit of terrestrial rigidity falls some-
where between that measured by the weight of the Wasatch Range and
that measured by the weight of the water of the main body of Lake Bon-
neville, or in more general terms, that a mountain of the tirst class is the
greatest load that can be held up by the earth, and is therefore an expression
of its strength or of the limit of elasticity of the material of its outer layers.
Fully to realize the nature of this measure, it is necessary to give it
numerical expression, and to this end a few computations have been made.
It is evident that the maximum strain produced by a load depends in
part on its distribution, and especially that a long ridge taxes rigidity less
than a compact mountain mass of the same weight. It appears to me that
a very long range causes no greater strains than a shorter one having the
same cross section, and I have therefore conceived the Wasatch Range to be
fairly represented for this purpose by a division of it including the highest
peaks and having a length not quite double its width. This di\ision
extends from the Provo River northward to the low pass at the head of
Parley's Canyon. Its estimated volume is 200 cubic miles.
Similar considerations lead me to base the estimate for Lake Bonne-
ville on the main body instead of the entire lake, excluding not only the
Sevier body but Snake Valley, Wliite Valley, and Utah Valley bays.
Thus defined, the load of water amounted to about 2000 cubic miles, equiv-
alent in weight to 730 cubic miles of rock. On the assumption that the
strains produced by the lifting of this load were only in minor part relieved
by viscous flow, it is inferred that the limit to tlie superficial rigidity of the
earth is expressed by a load of 400 to 600 cubic miles of rock (1670 to
2500 cubic kilometers).
There are four classes of topographic features with which tliis measure
may advantageously be compared, and by which it may perlia])s be tested.
The first is mountains of addition, or mountains produced by the mere addi-
tion of matter to the surface of the earth. IMost volcanic cones are of this
class. The second class consists of mountains by subtraction, or residuary
390 LAKE BONNEVILLE.
mountains clue to the removal of surrounding material. The third class is
intermediate, including addition and subtraction, as when the extrusion or
intrusion of volcanic matter produces a resistant mass cnpable of preserving
against erosion a residuary mountain. The fourth consists of valleys by
subtraction, or valleys eroded fi'om plateaus. Mountains and valleys due
directly to diastropliism are not in point, because, as they an; the super-
ficial expression of indviiown subterranean changes, we can nut be sure in
individual cases that their existence is independent of the sul)tcrr;inean dis-
tribution of densities. For similar reason, a volcanic inoinit.iin whose
building has been accompanied by subsidence of tlu^ subjacent tcrrane can
not be used for comparison.
The contour maps ])repared by the geogi-a])hic branch of the Survey
enable me to give the volumes of some of the most imjxtrtant American
examples of these various classes with a degree of precision (piite sufficient
for the purpose. By their aid each of the following' features was referred,
not to sea level, but to the plane of the surrounding country, and its vol-
ume was computed.
San Francisco Mountain is a volcanic cone standing alone on a high
plain, and tlie strata about its base are almost undisturbed ; it is a typical
mountain by addition. Its volume is 40 cul^ic miles.
Mount Shasta is a volcanic cone standing in a region of disturbed
strata, but there is no evidence of subsidence due to its load. Its volume
is SO cubic miles.
Mount Taylor is a volcanic cone standing on a plain tioored with hard
lavas. The degradation of the surrounding country has converted the mA-
canic plain' into a great mesa or table mountain. The cone and mesa
together, constituting a mountain by combined addition and subtraction,
have a vol nine of 190 cubic miles.
Tlie Henry Mountains and the Sierra La Sal consist each of a grou])
of laccolites — volcanic additions by intrusion — and of other rocks preserved
bv them from the erosive reduction sustained bv the sin-rounding ])lateau.
Their vohimes are respectively 230 and 250 cubic miles.
The Tavapiits plateaii of the Green River basin, otherwise Ivnown as
Roan Mountain, is a great mass of inclined strata carved out by the unequal
U S. GEOLOGICAL SURVEY
U^J-'Jl B^'I'II'TE-.TLLE FL. LI
Juhut:. Bien it <;•:■ Lith
.., U I H }:vi.sl..i
SKETCH MAP OF
BLACK ROCK AND VICINITY, UTAH
PREPARED TO SHOW THE POSITION OF
THE GRANITE POST KNOWN AS THE
BLACK ROCK BENCH.
Surveyed in 1877, by G.K.GilbeiL .
MOUNTAIN VOLUMES. 391
degradation of a still greater anticlinal. Its determining cause is a thick
layer of resistant rock lying between thick layers of yielding rock, and it
stands between two nionoclinal valleys due to the excavation of the yielding
layers. Its volume standing above the level of the adjacent valleys is about
700 cubic miles.
The Grand Canyon of the Colorado is a valley cut from a great })lateau
of stratified rock. The plateau has a fault structure of its own, but the
canyon and the fault structure have different directions and are manifestly
independent. The volume excavated to form the deeper part of tlie canyon,
from the mouth of the Little Colorado to the mouth o( Kanab Creek, is 350
cubic miles.
The Appalachian Mountains are traversed for nearly a thousand miles
l)y a great valley following the outcrop of yielding rocks, and it is probaV)le
that we have here a valley by subtraction. For the same reason that
determined the selection for measurement of a portion only of the Wasatch
Range and of a portion only of Lake Bonneville, measurement was not
made of the whole of this valley, but only of a limited part. It was assumed
that a section with length fifty per cent, greater than breadth, and selected
where tlie valley is broadest, fairly represents the strain-producing power
of the whole valley. The portion thus selected lies 600 feet below the mean
height of the Cumberland Plateau on the northwest and 1000 feet below
the mean height of the mountain district of North Carolina on the southeast,
and its volume, computed from the mean of these, is 800 cvubic miles.
All of these various features except two fall within the indicated limit
of GOO cubic miles, but the limit is exceeded by the Tavaputs Plateau with
700 and the Appalachian valley with 800 cubic miles. There are qualify-
ing considerations in each case. The plane above which the volume of the
Tavaputs Plateau was computed was that of the low valleys adjoining it;
|)erhaps a more suitable plane of reference would have been the general
level of the surrounding country. The density of the rock of the plateau
is probably less than 2.75, the density assumed in reducing the volume of
the abstracted lake water to equivalent rock volume. The Appalachian
valley lies in a region of great corrugation, and its trend coincides with the
strike of the orogenic structure. That structure unquestionably involves
392 LAKE BONNEVILLE.
inequalities in the distribution of subteiTanean densities, and it is possible
that the strains due to the valley are lessened by the presence beneath it of
exceptionally heavy matter. But after giving due weight to these considera-
tions, it must still be admitted that the measure of strength does not stand
well the test applied. It is indeed possible that a true measure has Ijeen
found, and that it is illustrated by the Bonneville, Tavaputs, and Ai)palachian
phenomena, but we can not deny the equal possibility, first, that the strength
of the earth varies so widely, in different places that a measure discovered
in the Bonneville basin serves merely to indicate the order of magnitude of
a measure of the average strength, or second, that the unloading of the
Bonneville basin occasioned no greater strains than the crust was able to
endure, and that the coincidence of unloading and uparching was a coin-
cidence merely.
CHAPTER IX.
THE AGE OF THE EQUUS FAUNA.
THE FAUNA AND ITS PHYSICAL RELATIONS.
As the Equus fauna is not known to occur in the Bonneville Basin, the
presence of this chapter requires explanation. In considering the relation
of the Bonneville history to glacial history, it has been found necessary to
consider also the glacial and lacustrine records of the Mono and Lahontan
Basins; hence the sixth chapter contains an exceptionally full discussion of
the relation of the later lacustrine history of the Great Basin to general
geologic chronology. The Equus fauna is so connected with that lacustrine
history that the geologist can best discuss its age in that connection. The
present chapter is a corollary to Chapter VI.
The same explanation serves to account for the discussion of the fauna
by the present writer, who has not visited the chief localities of its occur-
rence, but derives his knowledge of its geologic relations from the writings'
and notes of Russell and McGee.
Equus appears to have been first used in the nomenclature of geologic
history by Marsh, in an address read to the American Association for the
Advancement of Science in 1877." The Equus beds are there made an
upper division of the Pliocene, and they are characterized in a table accom-
panying the address by the genera Equus, Tapirus, and Elephas. An exam-
ination of the text shows that none of these genera are credited to the lower
Pliocene, but that all are credited to the post-Tertiary. The characteriza-
tion thus fails to separate the Equus fauna from the Pleistocene, and as no
'Fourth Ann. Kept. U. S. Geol. Survey, pp. 4r)8-461. Science, vol. 3, 1884, pp. 322-323.
-The Introduction and Succession of Vertebrate Life in America. By O. C. Marsh. Proc. A. A.
A. S., vol. 26, 1878, p. 211.
393
394 LAKE BONNEVILLE.
locality is mentioned, it leaves the fauna undefined. Two years later the
fauna was charactei'ized hy Cope by the following list of mammalian spe-
cies.^ Those of the left hand column are extinct, those of the ridit hiiiid
column living.
Mylodon sodalis. Tliomomys near vlushis.
Lutra uenT pincinaria. Thomomys talpoides.
ElephiDi primifjeuhis. Caslor filirr.
Equus occidentaUs. Canis lalruns.
Equus major.
Anchcnia henierna.
Avchenia magna.
Anchenia vitakeriana.
Cerims fortis.
As the species of this list Avere found together at one horizon and in
the same locality, they afford a definite and tangible basis for discussion,
and I shall consider them as the Equus fauna, despite the fact that they fail
to include the genus Tapirus referred to it by Marsh. The locality was de-
scribed by Cope as lying thirty or forty miles east of Silver Lake, Oregon,^
and he styled it "Fossil Lake." Russell, who visited the place in 1882,
speaks of it as a few miles eastward of Christmas Lake.
The formation in which the bones occur is lacustrine, as shown by its
shells. It constitutes the floor of a desert valley, and has suffered scarcely
any erosion, though the sand dunes traveling over it suggest that its surface
may have been somewhat degraded by wind action. All about the sides
of the valley are shore-lines, and above these shore-lines the lake beds are
not found. Just as in the Bonneville and Lahontan basins, the physical
relations indicate that the shore-lines and lacustrine sediments are coordi-
nate products of the same expansion of lake waters.
The Christmas Lake basin is part of the Great Basin, and lies L50
miles northwest from the Lahontan shore-lines. Each closed vallev of the
intervening region has its ancient shore-line and associated lake beds. Each
of the old lakes thus demonstrated stands witness to climatic oscillation,
and their geograi)hic relations leave no room for question that they jjertain
to the same climatic oscillation and therefore have the same date.
'E. U. Cope: Bull. U. S. Geol. & Geofr. Survey of tlio Territories, vol. 5, 1879, p. 48.
'Americau Naturalist, vol. 16, 18e2, p. 194.
CORRELATION OF EQUUS AND LAHONTAN FAUNAS. 395
The mammalian remains obtained from the Lahontan l)c(ls inckide a
great proboscidian (^Elephas or Mastodon), a llama, one or more horses, and
an ox. No skeletons were found, and the dissociated bones and fragments
of bones are not such as to permit the recognition of species; but Prof.
Marsh, to whom they were submitted, was able to say with entire confi-
dence that the specimens as a whole belong to the Equus fauna. Having
myself compared the Lahontan collection with the collection made by Mr.
Russell at the Christmas Lake locality, I may be permitted to add that I
share Prof. Marsh's confidence in the identity of the faunas.
The correlation receives additional support from the lacustrine shells.
Russell repoi'ts from the l)one beds near Christmas Lake the following
species:'
Sphwriiim dcntatum. Limnopln/fta hiilimoides.
PifiuliHin nltrnmontanum. Garinifex newhcrryi.
Helisoma trirolvis. Valvatn rireiis.
Gyraiihis rermicularis.
None of these are extinct, and all have been found in Lahontan strata.
Nearly all of the bones obtained from the Lahonton strata were found
at a horizon somewhat above the middle of the upper division of lake
beds. At "Fossil Lake" the bones were found at the top of the formation,
but we know nothino- of the thickness of the formation. Unless the Fossil
Lake formation is much thinner than the Lahonton, the date of its discov-
ered mammalian fjiuna is a trifle later.
The physical relations recited above, and the associated paleontologic
relations, show that the Equus fauna, as illustrated by its type locality,
belongs to the epoch of the Upper Lahontan. It therefore falls, as a mat-
ter of general chronology, in the later Pleistpcene.
This conclusion ditfers widely from that reached by purely paleonto-
logic methods, for these refer the fauna to the later Pliocene. Before they
are considered, attention will be called to a possible ambiguity, and one of
the lines of physical evidence will be amplified.
The term Pleistocene is used by geologists in two senses, one of which
may be characterized as chronologic or general and the other as physical
' Fourth Ann. Eept. U. S. Gcol. Snrv., p. 460.
396 LAKE BONNEVILLE.
or local. In Europe the later part of Cenozoic time was tUstingtiislied 1)\-
a series of physical events including one or more epochs of exce})ti()nal
cold and exceptional expansi(»n of glaciers. In European nomenclature
Pleistocene is applied to the period of time occupied by these events, and
also to the events themselves, and this without confusion. In North Ajner-
ica the later Cenozoic history included a series of events of the same gen-
eral character, and for these we have borro\\ed the name Pleistocene, or
its synonym. Quaternary. The time covered by these events may or may
not coincide with the Pleistocene period, and until it is shown so to coin-
cide, our imported term is ambiguous. It is primarily in the physical
rather than the chronologic sense of the term that the Upper Lahontan
and the Fossil Lake beds are found to be late Pleistocene. Properly to
characterize them in the chronologic sense — with reference to the period
including the glacial and interglacial epochs of Europe — it is necessary to
take account of the work of land sculpture and its relative progress in dif-
ferent places.
When a surface shaped by some agent other than atmospheric — a sea
floor, for example, a moraine, a shore terrace, or a terrace modeled by
man — is exposed to atmospheric agencies, its sculpture begins. For a long
time its original feattires continue to be the characteristic ones, but they
eventually become subordinate and finally disappear. The original foriTis
at first are new and fresh, then old, worn, and hard to discover; and finally
the fact that they once existed can be known only from the internal structure
of the deposits to which they belonged. So long as the original form is
discernible, it yields to the geologist evidence of relative newness or rela-
tive age. Such evidence as this is not readily formulated, but it is con-
stantly employed by the field geologist in the study of the surface. Indeed
it affords one of the most important liases of tlie wide spread opinion tliat
glaciation was simultaneous in Europe and America.
The abandoned lake shores of Christmas Valley and of the Lahontan
Basin, the lacustrine plains below them, and the correlated glacial moraines,
are all of youthful habit, as youthful as the "parallel roads" of Glen Koy
and other surface features marking the wane of glaciation in Scotland.
The lake shores and sea shores associated with tlie latest Pliocene beds of
COMl'AKATIVE SUULPTUKE. 397
Europe are eitlior iinrecog-nized, or else, as in the case of the Enghsh Cray,
known only by their internal structure. The plains of their upper surfaces,
where not covered by glacial or volcanic deposits, are either obsolete or
obsolescent. The topogra})liy created in the presence t)f the Equus fauna
is young; that created in the presence of the European Pliocene fauna is
old. With the aid of this additional link in the chain of physical evidence,
the geologist ties the Equus fauna, not merely to the American glacial or
Pleistocene history, but to the Pleistocene time division.
The ancient Lake Bonneville, the ancient Lake Lahontan, the ancient
lake of the Mono Basin, the ancient lake of the Christmas Lake Basin, and
numerous smaller extinct lakes of Oregon and Nevada, are tied together by
community of physical characters — freshly bared sediments, conforming to
the slopes of surface and surrounded by freshl}- formed shore-lines. Many
have yielded shells of recent species. Two, those of the Lahontan and
Christmas lake basins, have yielded the same mammalian fauna. The
two largest, Lahontan and Bonneville, have yielded detailed and parallel
physical histories. The analysis of climatic factors correlates them with
ancient glaciation in neighboring mountains, and their shores are carved
from and built around late-formed moraines of the Wasatch Rangre and the
Sierra Nevada. The detailed history shows two lacustral epochs corre-
sponding to two glacial epochs, and correlates the mammalian fauna with
the later half of the later glacial e[)i)ch. Presumptively this date falls very
late in the Pleistocene period. The phenomena of comparative sculpture
show that it is at least later than tlic latest Pliocene of Europe.
THE PALEONTOLOGIC EVIDENCE,
So far as I am aware. Cope alone has stated the jjaleontologic grounds
for referring the Equus fauna to tlie Pliocene. Comparing it with the sub-
Appenine fauna of Europe (Pliocene), he says— "The characteristic of this
fauna is the fact that the species belong mostU' to existing genera. . . In
the Equus beds of Oregon, a few extinct genera in like manner share the
field with various recent ones, while not a few of the bones are not distin-
guishable from those of recent species." Li a succeeding paragraph he
adds: "As a conclusion of the comparison of the American Equus beds in
398 LAKE BONNEVILLE.
general with those of Europe it may be stated that the number of identical
genera is so large that we may not hesitate to [)arallelize them as strati-
grapliioallv the same.'"
Three eategories of evidence are here used: (1) the relative abundance
of extiuft genera in the two faunas, (2) the relative abundance of extinct
species iu the two faunas, (3) the abundance of genera common to Ijoth
faunas.
The first and second categories embody the nu;thod devised by Lyell for
the classifit-ation of Tertiary formations, a inetliod Ijased on the })ercentage
in each fauna of living or extinct forms. Faunas with the hjwest per cent of
recent forms were grouped together as Eocene, those with a certain higher
per cent were called Miocene, and so for the Pliocene. The method rests
on a generalization from observation and on a postulate. The generaliza-
tion is that from the earliest Eocene time the fades of life has "■raduallv
approached the present fiicies. The postulate is that the rate of change has
been uniform in all places. If the postulate is true, the method of L\-ell
can yield exact time correlation; otherwise it can }'ield only approximate
time results. Lyell himself disclaims belief in the postulate and regards
his classification as cln-onologically imperfect.^
'These passages occur ou pages 47 and 48 of a paper on Thu Kelatiousof the Horizous of Extinct
ViTtel>rata of Eiirupo ami North America, ]mbli,she(l in volume V of the Bulletins of the IT. S. Survey
of the Tirritoiies. Ou paj;e 4'.) the correlation of the Eiiuns beds with the Pliocene is characterized
as the "exact idcutilicatiou " of a restricted division. The autlior's conlidence iu the correlation was
not materially shaken by a pridiininary statenieut of the physical evidence made by the writer to the
National Academy of Science iu 1886. See American Naturalist, vol. \.\I, 18-i7, p. 4.jlt. In the jiassa^e
last referred to Cope says: "This gentleman [Gilbert] has expressed the belief that the beds of this
age are not older than the glacial ejioch, because they embrace the bases of some of the moraines of
some of the ancient glaciers of the Sierra Nevada. It remains to be proven, however, that these
moraines are of true glacial age, since they are of entirely local character. The preseuco of so many
mammals of the fauna of this valley of Me.xico would not support the belief iu a cold climate."
When the moraines referred to were lieing formed, the Sierra Nevada bore eu its back a mer-de-
glace as extensivi; as that of the Alps, and a host of glaciers llowed from this to the valleys below,
reaching altitudes from (i,(IOII to ",),000 feet lower tiian the littli> glaciers that now cling to a few of its
peaks. At the sane^ time there were also great glaiuers lu the Wasatch Mountains. Whatever infer-
ences these phcncMuena yield as to the contemporaneous climate of \\w. Great Hasin a])pears to me ipiiti'
independent of the question of thinr correlation with a glacial ep leh souu'where else. If the glaciers
prove a cold climate iu the Great Basin, then the animals that Icit their bones in the contemporaneous
lake sediments of the Basin lived iu a cold climate. If the animals could not live iu a cold climate,
then it is shown that the valleys of the Great Basin were warm despite the icoou the high ii.onntains.
The question ot' geologic date is not involved.
The value of the Ecpius fauna as an index of contemporaneous climate has already been discussed
in chapter VI of this volnmi'.
■'Sir Charles Lyell. M.anual of Geology, IJth ed. New York. p. III!.
METHODS OF PALEONTOLOGIO CORRELATiOISl. 399
The third category of evidence, the abundance of common elements in
two faunas compared, is that ordinarily used in paleontologic correlation,
and it aj^plies to the older formations as well as to the Cenozoic. The
method of using it is analogous to the assignment of commercial colors to
their approximate positions on the prismatic scale, and may be character-
ized as a method of matching. Having in one district a number of faunas
determined by physical relations to be successive, the paleontologist com-
pares a single fauna of another district with each of these severally and
" correlates " it with tlie one with whicli it has most in common. The prin-
cipal check on this method lies in the consistency or inconsistency of its
results with one another. When two faunas of one district are separately
compared with the faunal scale of another district, their relative ages as
inferred from the results of matching is usually the same as shown by their
physical relations, but there are a few exceptions to this. Again wlien
l)iotic data of two or more kinds, as for example vertebrate fossils, inverte-
brate fossils and fossil plants, are separately employed for correlation by
matching, the results are often accordant, but they are also often discord-
ant. How far the discrepancies of result are due to imperfection of method
and how far to imperfection of data, is not known, but it is generally
admitted that there are limits to the applicability of the method. The
greatest discrepancies in its resuhs liave been found wlieu the formations
compared lie far apart, so as to fall in different faunal j)rovinces; audit
may be said in general that its value varies dii'ectly with the degree of
resemblance'of the faunas compared. Where the whole number of common
forms or of common types is small, cttrrelation is less precise than where
the lunnber is large.
In order to gauge the Equus fauna by the accepted scale, I iia\e
selected a series of European faunas more or less restricted geographically
and of well-known age. They are (1) the Lower Pliocene of Montpellier,
France, (2) tlie Upper Pliocene of the Arno Valley, Italy, (3) the Pleisto-
cene of Great Britain, (4) the living fauna of Europe. The genera and
species of the land mammals of these faunas have been compared with
those of the Equus fauna and the accompanying ta]:)le constructed.
400
LAKE BONNEVILLE.
The table includes only mammalian faunas. Cope has reported from
the same Oregon locality ten species of birds' and two of fishes,^ but these
are not at present available for purposes of correlation. As it is known
that the general rate of evolution differs in different classes of animals, the
entire Fossil Lake fauna can not be considered together. The birds can
not be separately used because of the scantiness of avian data in the Euro-
pean faunal scale. The fishes are themselves too few for profitable com-
parison.
Table XVII.— Summary of Paleontologic Data for Ike Determination of the Age of the Equua Fauna.
TciTustrial mamnjaliau fauDas.
Available for com-
pariBon.
Method of Lyett.—
Peicentace of ex-
tinct
Method by match-
ing.— Xutubi-r in
cui'ntnnn with the
Eiimirt fiiiina.
genera, speciea.
genera.
ypeciea.
genera.
species.
mauy | many
27 48
9 ' 13
18 29
14 15
0
7
*n
0
19
69
4
6
1
2
Pkiatiiceno (Great Britain)'
UpptT Pliocene (Val d'Arno)*..
Lower Pliocene (Moutpellier)*...
11
21
100
100
«6 0
2 0
< Britisli Pleistocene Mammalia. By W. B. Dawlsins and \V. A. Sanfonl. Palaeontographical Society, vols. 18 and
32, 1866 and 1878.
Plcistocei.o climate, etc. By W. Boyd Dawkin.i, Pop. Sci. Review, vol. 10, 1871, pp. 388-397.
'V. I. Forsyth Major. Atti Soc. Tosc. Sci. Xat., vol 1, pp. 39-40 and "Proc. verb.," vol. 1, p. v.
^Gervais, quoted by Major. Atti Soc. To.hc. Sci. "Nat., vol. 1. pp. 224-225.
*ln a publication Hubaequent to the one tin wiiicli Ibis table is b.aaed. Cope cstablislies a now genus, Holomenucug,
to which ho transfers the species o( Ajichenia in the Equus fauna. This doubles the number of e.\tinct genera in tlie fauna
and rai8e,s its percentage fioni U to 22.
^Tliis number includes the genus iufra, which is not reported from this formation. As it is reported from Ihe
preceding and following formations, its existence at that time can not be questioned.
The numerical results by the matching method appear in the two col-
imms ;it tlie right. The six geneni of tlie Equus fauna foxmd in the upper
Pliocene are identical with those of the Pleistocene, and include those of
the lower Pliocene and living faunas. The two genera found in the Pleis-
tocene l>ut not in the living fauna of Europe are Equus and ElvpJias, which
persist in other continents. One species, Castor fiher, is conuuon to the
Equus, Pleistocene, and Recent faunas. EJcphds jmmigenius, common to
the Eqiuis and Pleistocene, is said to occur in Europe exclusively in the
Pleistocene. The evidence from genera is ambiguous. That from s])ecies
> Bull. U. S. Survey Terrs., vol. 4, 1878, p. 369.
«Americau Naturalist, vol. 12, 1878, p. 125.
THE PALEONTOLOGIO EVIDENCE. 401
tends to correlate the Equus fauna with the Pleistocene of Great Britain,
but the number of common foiTns is so small that their testimony lias little
\\'eight.
The numerical results by the Lyellian method a])})ear in tiie middle
pair of colunnis. The Equus fauna agrees with the Up})er Pliocene in its
ratio of extinct genera; and in its ratio of extinct species it stands rather
nearer the Pliocene than the Pleistocene. Tlie evidence from genera is
weakened by the fact that the numbers involved are very small; of 9 gen-
era from Fossil Lake 1 is extinct, of 1<S from the Arno Valley 2 are extinct;
tile discovery of a few more bones might cause A\i<le di\'ergence of the
ratios. The evidence from species is hard to interpret, because all of the
Pliocene species are reported extinct. Does a fauna with one-third of its
forms living stand nearer to one with no living forms or to one with four-
fifths of its forms living? Perhaps the proper interpretation of this evidence
woidd assiji'M a date at the close of the Pliocene and be<>innin<>" of the Pleis-
tocene. It certainly does not agree with the physical evidence in indicating
late Pleistocene.
If all this paleontologic evidence coidd lie pro])erlv coml)ined, giving
each element its due weight, the resulting indication of date would he
later tlian tlu^ upper Pliocene of the Arno Valley and earlier tlian the middle
of the Pleistocene of Great Britain. It might fall in an assumed interval
between the two time divisions, or it miglit fall in tlie earlier part of the
Pleistocene.
At the very l)est, the ilate inferred from the physical tacts and the
date inferred from the biotic facts differ liy more than half the extent of
the Pleistocene jieriod. Botli can not be triie; which sliould l)e accepted?
For my own jiart 1 do not hesitate to prefer the physical I'videiice and llie
later date. I hold with Lyell that "we can not presume tliat tlie rate of
foi-mer alterations in the animate world, or the continual going out and
coming- in of species, has been everywhere exactly ecpial in equal quantities
of time;" and the Equus fauna seems to me to illustrate the principle. It
may perhaps be found, wdien the fauna is much better known, that its
features correspond closely with those of the contemporary fauna in
Europe, but for the present it appears that the mammalian fauna of the
MON I 26
402 LAKE BONNEVILLE.
Groat Basin experienced a greater change at the close of the Pleistocene
tliau did that of Europe.
In the study of tlie Pleistocene of Europe, geology and paleontology
have worked together with adinii-able results. The geologic relations have
given to paleontology tlie sequence of its faunas; paleontology has recii>
rocated by correlating the deposits of extrn-ghicial regions with elements
of the glacial history; and through such cooperation a bewildering multi-
plicity of data are being mai'shaled into a consistent though complex sys-
tem. In America the same benefit should result from the same coopera-
tion. Some Pleistocene deposits can be assigned dates through their rela-
tions to glaciation, and when the faunas and floras of these are known,
paleontology can contribute much toward the discovery of the Pleistocene
history of districts remote from glaciers. For this purpose the Lyellian
method of percentages is, in my judgment, far less valual)le than the method
by matching; but the standard scale for matching should be an American
scale, based on physical studies in the region of Pleistocene glaciation and
its immediate vicinity.'
' While these pages are passing through the press, a vohime is published by Messrs. Felix and
Loiik, cimtaiiiiug an account of Pleistocene lacustrine formations in the Great Valley of Mexico. In a
general way the phenonicuii of the Ijonneville and Lahontau basins are there repealed, but the history
ot the climatic oscillation has nut been fully nuidc out. In undisturbed strata, forniiug a continuous
series with lake sediments now being deposited, there have been found bones of thirteen maunnaliau
species, and two of these species are identical with members of tlu^ Christ ui.-i.s Lake fauna. (Beitrjigo
znr Geologio und Paliioutologio der Kepublik Mexico, Vou Dr. J. Felix uud Dr. 11. Leuk. Part 1.
Leiiizig, 18U0, pp, (55-06, 7y-88.)
APPENDIXES.
A.— Altitudes luid tbeir detcrmluatiou. By Albert L. Webster.
15. — On the deforiuatiou of the seoiil '»y the removal, tbrousli evaiioiation, of the
water of Lake Bonneville. By K. S. Woodward.
C. — On the elevation of the surface of the Bonneville Basin by expansion due
to change of climate; By R. S. Woodward.
403
APPENDIX A.
ALTITUDES AND TIlEIIi DETERMINATION.
By Albert L. Webster.
In connection witli the study of the records of the ivnciont Lake Bonneville, it
hecame a matter of interest to ascertain the present relative altitudes of points scat-
tered alonj;- its fornier perimeter. A comi)lete and thoroughly satisfactory investiga-
tion of the subject being' impracticable from economic considerations, it was made
■subsidiary to the more general historic study of the lake, and its results are accord-
ingly incomplete or lacking where such study would not permit of a more extended
investigation. As far as practicable altitudes were obtained of points representative
of the entire shoreline. To accomplish this a large area of country had to be
traversed, and it was -ifcessary to employ all available means and methods for the
collection of tlie data. All heights are referred for comparison to a common datum
l»()iiit, arbitrarily cliosen, the zero mark of the lake gauge at the Lake Shore bathing
resort.
The measurements and observations here brought togetlier are not my own alone,
but were made by many persons and at various times. In the following pages the
attempt is made to ari'auge them in such order that the critical reader can readily
learn the essential nature of all the data on which each separate determination of
altitude is based.
SCHEME OP TABLES.
Taule XVIII. Differences of aUitiulo determined by trigonometric oljservations.
XIX. Dififereuces of altitude determined Ijy Ij.arometric oliservations.
XX. Reduction of various lake gange zeros to tlie Lake Shore datum.
XXI. Gauge records, showing the height of the water surface of Great Salt Lake at various
dates.
XXII. Ditferences of altitiule from railroad survey records.
XXIII. DitFereiJCes of altitude by special spirit-level determinations.
XXIV. Reduction of results to Lake .Shore gauge zero as a common datum.
XXV. Comparative schedule of altitudes of points on the Bonneville shoreline
XXVI. Comparative scliednle of altitudes of j>ointa on the Provo shore-line.
XXVII. Comparative schedule of altitudes of points on the Stansbury shore-line.
XXVIII. Ditferences in altitude of the Bonneville aud Provo shore-lines at various localities.
XXIX. Differences in altitude of the Provo and Stansbury shore-lines at various localities.
By reference to this scheme of tables it will be seen that hypsometric material
403
has been gathered from the five following sources
406
LAKE BONNEVILLE.
(1) From deterrainatious based upon trigonometric observations.
(2) From determinations based upon concurrent barometric observations.
(3) From the records of the fluctuations of the present Great Salt Lake.
(4) FroQi the records of various railroad surveys.
(o) From especial determinations made with the surveyor's spirit-level.
TRIGONOMETRIC DATA.
The few results obtained by the first method and jucscnted in Table XVIII were
derived by comi)utation from measurements of angles of elevation and depression
with accompanyiuf;- short base-lines. Tiie angles were measured with the ordinary
surveyor's (ransit, reading to minutes on the vertical limb. The base-lines were
measured with a steel tape.
The results are recorded in feet and tenths of feet, but it is not intended to assert
that they are true to the nearest tenth. They are probably true to the nearest foot.
In combining determinatiims of various kinds it has been found convenient to use the
same notation for all, and the tenth of a foot has been <-hosen as expressing the pre-
cision of the most accurate of all the measurements — thc^ shorter lines of spirit-level-
ing. For the purposes of the Bonneville investigation it would be sufiicient to stop
at the decimal point, as all the results of measurement are combined with observa-
tions involving an uncertainty of several feet; i)nt it is conceived that some of the
data may have other uses, and for the sake of these the tenths are retained.
Table XVIII. — Differences of Altitude deiermiind hij Triijntinmetrie Olmerrntion-i.
Vicinity of-
Feet.
415.1
301.1
410. 7
310.0
3G3.0
Dovo Ureek —
Kelton
Bonneville abore-line above Prove sbore-line
,io
Mallin
do . . . .
Matlin
Snowavillo
BAROMETRIC DATA.
The section of country including the long southern arm of the old bike, now the
Escalante Valley, was practically accessible to no better hyiisometiic. method than
that of concurrent barometric observation, and that method was accordingly adojited
for its investigation.
This region in general lies two huntlred miles south of Salt Lake City, and its
nearest barometric base was the U. S. Signal Ofilec in that city. It was deemed
advisal)le to establish an intermediate sub-base station in the nearer neighborhood of
the field of itinerary ob.servation, to which to refer the new stations. The village ol
Fillmore, lying one hundred miles sonth of Salt Lake City, ottered especial natural
advantages for the location of snch a sub-base. It includes within its limits a jiortion
of the Bonneville siiore-line, thus allowing but slight disitaiity in altitude iietwet-n the
reference station and now stations. It is moreover situated about midway between
the southern field of study and the Salt Lake City i)rimary base, and affords, by the
comparison of its series of observations with that of the Signal Oflice. a criterion for
judging of the value of results from the observations at the new stations.
HEIGHTSBY BAROMETER.
407
Two barometers and psycbrometers were left here in the charge of an observer,
Mr. R. II. Smith, from July 29th to October 3ril, 1881. U])on the former of these,
hourly observations were made each day from 7 A. M. to 9 V. M. inclusive ; ui)0m the
latter, readings were taken daily at 7 A. M., 2 P. M. and 9 P. M.
The Survey did not establish a base station at Salt Lake City, but made use of
the ordinary observations by the U. S. Signal Service observer. Through the cour-
tesy of the Chief Signal Oflicer of the Army we were furnished with copies of sucii
])ortions of the records as were needed for our work, viz., the readings of barometer,
thernioineter and psychronieter at 7 A. M., 2 P. M. and 9 P. M., during the period
covered by the observations at Fillmore.
The altitude of the sub-base above the Signal Ofth^e at Salt Lake City was coni-
l)uted from a selected portion of the concurrent oi)servations at the two plaiies.
In order to avoid observations affected by abnormal atmosi)heric conditions, the
"reduced" barometric readings at the two stations were platted gra|)hically in close
proximity, with a common time scale. A marked parallelism of the resulting curves
between the dates of July 29tli and August 17th led to the acceptance of the recoids
included between those dates as a basis for the computation, and they alone weie
employed.
Three somewhat independent results were obtained for tlie difference of altitude
by considering sei)arately the means of the 7 A. M., 2 P. M., and the 9 P. M. reduced
readings at the two stations, Williamson's method and tables being employed.* In
each determination the terms t+t' and a + a' are identical, being derived from the
means of tlie temperature and humidity terms of the 7 A. M., 2 P. M., and 9 P. M.
records for the selected period.
7 a. HI.
2 p. m.
9 p.m.
k. Me.in of rrdiicol readings :it Salt Lako City
II. Mn:in of reduced rcadinjis at Fillmoro
Inr.hrtt.
2.'i. (ifi8
24.947
Fret.
24, 720. 9
23, 973. 8
Tvekea.
2.) 041
21. 91)7
Fret.
24, 693. 2
21,931.7
Inehes.
2.-). 013
24.81)8
Fret.
24.004.6
23, 922. 3
t+t' from means of 7 a. m., 2 p. m., and !) p. ni. tem-
perature reading.s at Salt Lake City and Fillmore ~
1510.92 F.
a + a' fi-om moans of 7 a. in., 2 p. m . ami 9 p. m. rela-
tive humidity reiluctions for Salt Lake City and Fill-
more = 0.60.
From Table l>i with argument h
First approximate difl'ercDce of altitude
From Table Dii
747.1
+66. 80
761. 5
+08. 15
742.3
+06.44
813. 90
-h6.21
829. 05
+0.32
808. 74
-1-6.14
Tiibles Dili to D,ii, inclusive, with general arsumrnts ( + ('
= 151°.92 F., a +a'= 0.60, lat.= 40°, and seoond ajiproxi-
mate dilTerence of altitude, give additional correction . . .
820. 17
835. 97
814. H8
Accepted result, mean of tlie three determinations,
823.7 feet.
'Professional papers of the Corps of Engiuccrs, U. S. Army. No. 15, Appeudix.
408
LAKE BONNEVILLE.
To the Fillmore station alone, as a base, have been referred all the itinerary
barometric records taken in tlie district south of it.
At the new stations no *'dry bulb" thermometer or psychroraeter readiufj^s were
talvon, and wliere such diita were necessary in the comi)utation of their altitu<les they
were snpidied from the Fillmore records alone.
Tablk XW.— Differences of AUiliide determined from Barometric Observations.
Vicinity of
Antelope Spring
(Lower Kscalaute
Uosert).
Fillninro
Giantsvillo
Kaiiosli
Meadow Creek
Point :in<l liefi-rt-nce.
North Twin Peak..
Pavant Butte
Pinto Canyon
Shoal Creek
South Twin Peak..
Siilplmr Springs
(Ertoalanto Desert)
Thermos
White HouDtain.
P.onneville >*hoie-line, 1 mile west of Spring, altove Fillmore anb-
ba.se harOTueter.
Sub-ba.se cistern barometer rtbrice H. S. Signal Office barometer at
Salt Lake City, Utah.
Bonneville shore-line above Provo shore line
Bonneville .shoreline on Kannsh Bnttf hil»w Fillmore anb-base
barometer.
Bonneville .shoreline, 1 mile east of tiitrance to canyon, above
Fillmore sub-base barometer.
Bonneville shore-line, 1 mile west of entr.ince to canyon, above
Fillmore sub-base barometer.
Camp on east bank Beaver River, hehnv Fillmore sub base batom-
etcr.
Bonneville aliore-line, 1 mile northwest,of Alilfonl, below I-'illmore
anb-haae barometer.
Bonneville sbore-line, 7 miles south of Milfonl. below Fillmore
sub-base barometer.
Bimneville ahore-line, east base of Peak, aboiw Fillmore sub base
barometer.
Bonneville ahorc-lino, ca.st baseof Butte, below Fillmore sub-base
barometer.
Bonneville sliore-line. west of entrance to canyon, above Fillmore
Mub-ba.se harometer.
Bonneville shctre-line, north of entrance to canyon, above Fillmore
riuh bxso barometer.
Bonneville almre-line, west base of Peak, below Fillmore sub base
barometer.
Bonneville shore-line above Fillmore suli-hase harometer
DitlVrence
in Altituile.
Bonneville shore-line, 2 miles east of Springs, behnv Filhiioie sub-
base baronuiter.
Bonneville Nhore-liue, 4 miles south of Springs, below Fillmore
sub-base barometer.
Bonuevilh> shore line. 7 miles south of Si)rings, below Fillmore
aub-base liarometer.
Camp, belo7t> Fillmore suhbuae barometer
Feet.
3fl. 7
ft2:t.7
381.3
17.3
296. G
294.5
21P.6
7fi 0
48. J>
L2
67.6
214.1
26.-.. ri
.12,5
45.2
76.6
48.7
42.1
474.1
.HEIGHTS B-Y BAKOMETEK. 409
LAKE RECORDS.
At various times spirit lovol lines Iiare been run from the surface of Great Salt
Lake to points on the ancient beaches in tlie near nei^liborbood of its present shore.
The records of altitudes thus obtained are not, however, directly comparable, suice
the surface of the lake is in a state of continual fluctuation, the records of which have
lieen referred to independent jjauges. It was accordingly nece.'sary to determine pii-
marily the relative altitudes of the zeros of the various gauges.
Previous to 1875 the record of the rise and fall of the lake is iturely a tradition;il
one. Such evidence, however, as is reliable, has been presented by Mr. Gilbert in his
chapter on " Water Supply," Powell's " Lands of the Arid Region," in which the rec-
ords have been referred to the level of the Antelope Island Bar as a datum.'
In 1875 a granite inonuineiit, graduated to feet an<l inches, was eretited by Dr.
John R. Park, of Salt Lake City, at Black Hock on the southern shore of the lake, and
upon this observations were made at intervals until October 9th, 1876, when it was
abandoned. Li connection with it, the Powell Survey jdaced a granite bench block
on the shore near iiy. A line of spirit-levels was subsecjuently run, which showed the
Black Rock MonunuMit zero to be 36.5 feet below the Black Rock Bench.
In 1877 another gauge was erected at Farmiugton, on the east shore of tlie hike,
in nil inlet. A stone reference point, planted on rising ground near by, and known
as the Farmiugton Bench, was found to be 12.9 feet above the zero of the Faniiington
gauge. Observati(>ns were made at intervals on the newly erected giuige until Octo-
ber, 1879, when it was rendered useless by the occurrence of a succession of hea\y
winds from the westward, which effectually barred the entrance of the inlet witii sand,
thus cutting ofl' its direct cominunicatiou with the lake. In anticipation of such an
occurrence, a third gnnge had been established at Lake Shore, live miles soiitii of
Farmiugton, and monthly records begun November 19th, 1879. This is known as the
Lake Sliore Gauge, and to its zero as a datum have been referred the various deter-
minations of which tiiis ai)pendix treats. (See Table XXIV.)
A general taliing tendency of tlie Lake for several years portended disqualifica-
tion of this gauge, and rendered the erection of a deeper set scale a matter of pieciin
tionary advisability. A fourth gauge was accordingly established at Garfield Land-
ing, three miles west of Black Kock. It consists of a stout strip of scantling, nine-
teen feet long, firmly si>iked to one of the piles of the steamer pier. It is graduated
to feet and iiicbes.^
On the 23d of -luly, ISSl, the Black Rock bench was found by spirit level to be
38.7 feet above the surface of the lake; at the same time the water washed the 7 ft.
9 in. mark of the Garfield gauge. Thus the zero of the latter is 4G.4 feet below the
Black Rock bench.
Table XX indicates the steps by which the various gauges have been reduced
to the Lake Shore zero.
'Ttie traditional record is repeated, with an addition, in this volume, pp. 2:W-243. G. K. G.
^Since tlie preparation of this Appendix, the Garfield gauge has been destroyed and renewed
Oee p. 232. G. K. G.
410
LAKE BONNEVILLE.
Table XX. — Reduction of various Lake Gauge Zeros to the Lake Shore Datum.
Point.
Intermediate Datum.
Uato.
Refi^ned to
Intermediate
Datnm.
Referred to
Lake Slioro
Gauge Zero.
Jan. 2:1, 1880 ...
+ 2.r<
+ 3.8
A "Temporary Bpnrh'' ,it
Farmington.
Lako Surface
do ...
+ 1.3
Farmington Gauge Zero
A "Temporary Bencli " at
Farmington.
Nov. .■!, 1879 . .
- 0.1
+ 3.7
Farmington Gauge Zero
do
+12. n
fie.G
+ 2.0
M!»r. 21 lo Mot.
25, 1881.
Qarfield Landing Gauge Zero
Mean Lake Surface
.. do
- 7.2
- 4.6
Lake Surface
G.arfifld Landin" Gange Zero
July 23, 1881 . . .
+ 7.7
+ 3.1
Black Hack Bench
do
+38.7
-34.5
- 2.0
+ .8
+41.8
+ 7.3
+ 5.3
+ 0.1
Lake Surface
Black Rock Monument Zero..
Lake Surface
IJlaclt liock Bencli
July 12, 1877 ..
. do
Lake Surface
Black Rock Monument Zero
Oct. 10, 1877 . .
Antelope Island Bar in tlio
Lako Surface
....do
- 0.5
- 3.4
"little cbannel."
A uote of uncertainty relative to tlie results depenilent on the Black Bock ob-
servation of July 12, 1877, must be introduced here. The observer's record of that
observation reads as follows:
Jut)/ 12, 1877. — Water washed higbest font mark of graduation on Dr. Park's [Black Rock] iiion-
iinient ; supposed to bo the two-foot mark.
The scale is neither numbered nor lettered, but subsequent conversation witli
Dr. Park led to the acceptance of the record in conformity with the su[)position of the
observer.
Confirmatory evidence is found in the close agreement of this determination of
the monument zero with a second determination, which joins t)ie monument zero to
the Farmington zero by reference to the lake surface. The difference in the two
results is less than two-tenths of a foot. As an interval of fifteen hours elapsed
between the readings of the two gauges the second determination was considered
only as a general check for large errors, and was not used in the reduction.
A table and platted curve showing the rise and fall of the present (Jreat Salt
Lake from September, 1875, to June, 1889, will be found on pages 233-243 of the mono-
graph of which these pages form an appendix. By means of the data contained in
that table the lines of leveling at various times connected with the water surface of
the lake were referred to the Lake Shore gauge zero. The specific data thus used are
here repeated in Table XXL
HEIGHTS OF LAKE SURFACE.
411
Table XXI. — Gauge Records, showing the height of the Water Surface of Great Salt Lal;e at various dates.
Gauge.
Date.
Ri'adinji.
Hciulit ..f
Trauiio Zoro
aliovn Zi'io of
Lake Shore
Gauge.
Height of
Water Sui fare
ahove Zi'io of
Lake Shore
Gauge.
Rlack Rock
Do
Fannington
LaUe Shore
Do
July 12,1877..
Oct. 19. 1877 . .
May 2, 1879 ..
Nov. 9. I87!>...
Nov. 12, 1880..
Nov. 29, 1880 . .
Dec. 11, 1880...
Ft. In.
2 0
0 10
1 4
2 G
1 9
1 8J
1 8J
Feet.
.'i. n
.1.7
IF
0
0
0
Feel.
7.3
0.1
.I.O
2.5
1.7
1.7
1.7
Do. .. ,
Do
RAILROAD RECORDS.
A fourth .source from wliicli data liave l>i>cii obtained to assist in the general
comi)i!ation, is Found in the records of various railroad surveys. Tiie results appear-
inj; in Table XXII in some eases have been derived from Gannett's " Lists of Eleva-
tions", 1877, and such are indicated by a star (*); iii other cases they are from tran-
scripts of official profiles kindly furnished by the engineers of the dittereut roads.
TAni.n XXII. — Differences of Attilude derived from Railroad Surrey Records.
Vicinity of
Poiuts Dutorinincd anil Poiuts of Kcferonco.
Feet.
Corinne Station (Central Paciflc R. R.) below Ogilen St.ation
Franklin Station ( Utah Nortliern R. R.) alioite 0;;<ieu Station
Leniington Station (LTtah Southern K. K. extension) above Salt
Lake City Station.
71.3*
213.0
456,0
20n. 0
707.5
42, 3*
517.0
280. 0
773.0
287.0
551.0*
Logan
Milfonl
Milfonl .Station (Utah Simthoru R. R. extension) above Salt Lake
City Station.
Ogden Station (Utah Central R. U 1 aboiie Salt L.ake City Station. ..
Summit (Utah Southern R.R.) atom- Salt Lake (.:ity Stat i mi
Reil Rock Gap Station (TTtah Northern R. R.) above Franklin Stalimi
Snnimit (U. S. R. R,) above Salt Lake City Station (U.S. R. R.)
Swan Lake St.ation (Utah Northern R. R.) above Franklin Station ..
lecoina Station (Cential I'aeitie R. R.) ahovc Salt Lake City Station
(U.S. R. R.).
Point of thi^ Mountain
Red llock Gap
SPECIAL SPIRIT-LEVEL DETERMINATIONS.
Table XXIII contaius the results of spirit-level determiuatioiis, made with espe-
cial reference to the study of the ancient lake. Check lines have been run wherever
practicable, and the mean of the origiual and duplicated work accepted. IJesults
thus verified are marked by a star (*) in the table.
Measurements made with Locke's hand level are marked thus (t).
412
LAKE BONNEVILLE.
Table XXIII. — Differences of Altitude hij Special Spirit-Level Determinationt.
Vicinity of
Points and References.
Feet.
1059.0
Aqni K:inj:o, Nortln-iiil
lioiinoville .shore-linn above lake siirrace, .Inly 2i<, 1877
Provo Hhorc-titie above lalio surface, July 28, 1877
678.0
Ilonnevillo .sliore-liiie tifcnwr liiko flui-face, Nov. 25, 18S0
1058. 4»
Provo sliure-Iiuo above lake .tuiface, Nov. 25, 1880
G7C.9
Stm.Hlmry slioro-liue above laUo surface, Nov. 25, 1880
.331.0
Blank Knck
liiiuiievilliisljori;-liuf, above lake aiirfnco, .Inly 12, 1877
>.m. 0
HIack liock Itench above Black Rock Monument zero
34. B
Provo shore-line ofiorc lake aurfacc, July 12, 1877
033. U
247.0
.Stauftbury shore-lini' above lake surface, July 12, 1877
Corinne Station (C. P. 11. It.) above lake snrfac o. May, 1873, (Wliechr
22.6
Cup Butte
l-'illiiiore
IJonnoville ahoro-lino above Provo sliort>-line
397.01'
19.4'
309. 01
Finli Spring
Uunne\ille cut- terrace above Prove cut-terrace
Bonneville shore-line on Franklin liutte afcorc l''raiiKliii Station (U.
N i:. R)
KG.O
Provo .shoreline on Franklin Bntte above Franklin Stariou (U.N.
R.K.)
201. 0
Kelton
Bonneville .shore lino above lake .surface, Aug. 11, 1877 (checked by
1017.5
,52.4'
r.akc Shore GauKe zero below Salt Lake City Station, tl. S. R. R
Bonneville shore-Iiuo above Lemington Station (tJ. S. R. R. extension)
380. C<
Logiin
Bonneville shore-line above Lo^an .Station (U. N. R. R.)
632.9
Provo shore-line rttoV(? Lo*;an Station (f.N.R.R.)
270.2
Milford
Bonneville shore-line above Millnnl Station (U. S. K. R. extension) -
152. 7 •
Camp on e.ast hank Beaver River Womi Milfor.l Station (U.S. R.R.
0>;il<-n
7.0
Bonneville shore-line above Ogden Station U. C. R. 11., (Prof. F. H.
Bradley, Ilavden Survey). -.
87G. Of
329. 1*
358.0
Pavant Batte
Point of the Mountain
Bonneville shore-line above Summit (U. S. R. R.)
Picusa Valley
Provo shore-line 6eioic Bonneville shore line
375.5
343.2*
'Ncuth Group," Bonneville .shore-line above Pi ovo shoreline
" Middle Group," Bonneville shore-lino above Provo shore-line
346.4*
Promontory
Red Rock Pass
Bonneville shore-line a&ore lake auiface, Aug. 23, 1877
1037.7
«B5. 8
303. U
Provo shore-line a&oi'c lake surfu'o, Aui^. 23, 1877 .. ,
Bonneville shoreline above Swan Lake Station (U. N. R. R.)
Salt Lake City
Bonneville shore. line above Salt Lake City, Meridian M'lnnment ...
845.9*
.Meridian Monument below U. S. Signal Si-rvice barometer
12. 6*
SaU Lake City St.ation |U. S. R. R.) Mow Meridian Monument ....
72.0*
S.alt Lake City Station {U.S. R.R.) above Lake surface, Dec. 11, 1881.
50.7*
Santaqain
Bonneville shore-lino above Sautaqnin Summit (U. S. \l. R )
75.0
Bonneville fthoro-line «6f*«f Provo shore-line
401.0*
1011.0
Stockton
Bonneville shoreline above lake surface, Mar., 1873 (M. F. Burgess)
Prove shore-line (j/'iow Bonneville shore-line
375,0
Bonneville shore-line above Teronia Station (C. P. R. R.)
Bonneville shore-line aborc Provo shore-line
367.8
Wellsrille
AVhite Mountain (Fill-
383.7
Provo shore-line on White Mountain above While Monnlnin
more.)
camp
68.9
Provo tufa deposits on Tabernacle Bntte Uva bed above camp
42.9
Willard
Bonneville shoreline above lake surface Oct 28 1879
974. Ot
621. Of
Provo shore-line above lake surface, Oct. 28. 1879.
UEIGUTS BY LEVELING.
413
COMBINATION OF DATA.
lu the schedule followiug (Table XXIV) a collection and combiuation is made
of results appeariuj? in some of the six tables preceding, so as to reduce tlie stations
to which they apply to the arbitrarily assumed Lake Shore zero datum. Tiie table is
arranged with reference to the latitudes of the points determined, beginning with the
most northerly.
Table X'K.IV. —Reditclion of Rumiltn to lite Lake Shore Gauge Zero as a Common Daliim.
Point.
L.^ke Surfaci-, IK-c. 1 1, 1880
Salt LakeCily Sl.ilioii (U.S. K. It.)
Ogdell Statiou
Fraiikliu Station ilT. N. K. R.)
Swan Laks Station (D.N. Iv. K.)
Bonneville aUore-lino, vicinity of Rod Itock Paaa
Franklin Station
HonneviUe sbore-linf* ini Franklin Butto -
Trovo 8bore-line on Franklin Butto
OK'len Station
Lo2!in StJltion (U. N. E. R.)
Bonneville .shore-line, vicitiity oT Logan .
Pi-ovo .shoi-e-line, vicinity of Logan
Lake aui'facp, Ang. 11, 1877; interpolated
Bonneville shore line, vicinity of Kelt<ni . . .
I'rovo shore-line, vicinity of Kelton
Lake snrface, Aug. 23, 1877; interpolateil
Bonneville shore line, vicinity of Promontory
Prove shore-line, vicinity of Promontory
Lake surface, tlct. 28, 187!»; interpolated
Bonneville ahore-liue, vicinity of Wilhird
Piovo .shore-line, vicinity of Willard
Salt Lake City Station (n.S.R.R.)
Teconia Station (C P. R. U.)
Bonneville shore-line, vicinity of Tecoma.
< )gden Station
Bonneville shore-line, vicinity of Ogden.
Salt Lake City Station
Salt Lake City Meridian Monument
Bonneville shore-line, vicinity of Salt Lake City
(Ist determination).
Intermediate Datum.
Lake Shore Gauge Zero . . .
Lake Surface, Dec. U, 1880 -
Salt Lake City Station
Ogden Station -
Franklin Station
'Swan Lake Station
Franklin Station .
do
Ogden Station .
Logan Station .
do
Lake Shore Gauge Zero
Lake surface, Aug. 11, 1877
Bonneville shore-line
Lake Shore Gauge Zero . ...
Lake surface, Aug. 23, 1877.
do
Lake Shore Gauge Zero . . .
Lake surfiice. Oct. 38. 1879
do
Salt Lake City Station .
Teconia Station ...
Ogden Station .
Salt Lake City Station.
Meridian Monument ..
From
Table
XXI
XXIII
XXII
XXII
XXII
XXIII
XXIV
XXIII
XXIII
XXIV
XXII
XXIII
xxin
XXI
XXIII
XVIII
XXI
XXIII
XXIII
XXI
XXIIt
XXIII
XXIV
XXII
XXIII
XXIV
XXIII
XXIV
XXIII
XXIII
Difference in
Altitude
referred to
Intermeitiate
Datura.
Ic
■t.
+
1.7
+
50.7
+
42.3
+
213.0
+
287.0
+
303. 0
■1-
620.0
-t-
2lil.O
-t-
206. 0
+
032. 9
+
278.2
-1-
0.8
-t 1017. 5
—
361.1
+
0.5
-1-1037.7 1
1-
005.8
+
2.6
+
974.0
+
621.0
+
5.01.0
+
3',7.8
+
876.0
+
72.6
+
845.9
Altitude
above the
Lake Shore
Gauge Zero
Datum.
1.7
52.4
94.7
307.7
594.7
897.7
307.7
933. 7
568.7
94.7
300.7
933.6
576.9
6.8
1024. 3
0i;3. 2
0.5
1044.2
672. 3
2.6
976 6
623. U
52. 4
803. 4
971. 2
94.7
970.7
52.4
125.0
970.9
414 LAKE BONNEVILLE.
Table XXIV. — lieduction of Results to the Lake Shore Gauge Zero as a Common Datum. — Continued.
Point.
Intermodi;ite Diitutii.
From
Table
Difference in
Altitude
referred to
Intermediate
Datum.
Altitude
above the
Lake Stioro
Gauge Zero
Datum.
Liiko SHifiice, May, 1873. Iiitcr|iolatLMl from
recorda not iucluded iu Taltli- XXI.
Feet.
Feet.
8.5
IJouiic'villd shore-Hue, vicinity of Salt Lalto City.
(2(1 determination. Thirt elevation is taken
+ 9C7.7
970.2
from Vol. Ill, p. 92, Report of Surveys West of
lOOHi Meridian).
Lakf surface, July 12, 1877
Lake Shore Gauge Zero - - -
XXI
-1- 7.3
7.3
UouneviUe .shore-line, vicinity of Black Rock ...
Lake surface, July 12, 1877
XXIII
+ 993. U
1000.3
do
XXIII
XXIII
-1- 633. 0
+ 247.0
040. 3
254.3
."^tauHbury Hhore-liue
do
Lake Surface, July 28, 1877; interpolated
Lake Shore Gaugi' Zero
XXI
-t- 7.0
7.0
IIonnevillcaliorc-liUL', uorlh end A«iiii Uan;;e (lat
Lake surface, July 28, 1877
XXIU
+ 1059. 0
1000. D
deterniinatiiiu).
I'rovo .shore-line, north end Aqui Kan;;e (lat de-
termination).
do
XXIII
+ 078.0
085.0
Lakoaiirfaco, Nov. 25. 1880; iulerpolatc'd
Lake Shoi-e Gauge Z-ro
XXI
+ 1.7
1.7
Bonneville shore-line, north enil of tlie Aqut
L:ike surface, Nov. 25, 1880
XXIII
•f 1058. 4
1060.1
Ran^xe (2d determination).
Provo shore-line, north end .Vqui K;iiinn (2d ths
do
XXIII
+ 076.9
078.0
termination).
do
XXIII
XXIV
XXII
-1- 331.0
332.7
.52.4
599.4
Salt Lake City Station (0. S. R. R.)
Summit (U. S. R. R.), vieiuitv of Point of the
Salt Lake City Station
+ 547.0
Mount;iiii.
Ronneville sliore-liue, vicinity of Point of Ihe
Mount:un.
U.S. R.R.Summit
XXIII
+ 358.0
957. 4
Provo shore-line. Point of the Mouiit;iin
Lake surface, Mcli-, IH73. luterpohiteil from ap-
XXIII
- 375.5
581.9
8.0
proxiriiiito d.ita not ineUnled in Table XXI.
Ronnevillo shore line, vicinity of Stockton
Lake surnuw.Mch., 1873
XXIII
+ 1011. u
1019.0
Provo shore-lino, vicinity of Stockton.^,
XXIII
XXIV
XXII
— 375. 0
014.0
52. 4
82J. 4
Salt L:ike City Station ( U. S. R. R )
Sautaquin Summit (0.S.R.R.)
Salt Lake City Station
+ 772,0
Bonueville shore-lino, vicinity of Santaqniu
Santaquin Summit (U.S. R. R.).
XXIII
+ 7.5.0
899.4
Salt Lake City Station (U.S. R. R.)
Salt Lake City Station
Lemiuglon Station
XXIV
XXII
.52. 4
507.4
89«.n
-(- 4,55.0
+ 38G.B
Bonneville shore-lino, vicinity of Lemiugton —
XXIII
XXIV
xxrii
125.0
137.5
U. S. Signal Service barnmoter at Salt Lake City.
Meridi;in Monument
+ 12.5
Fillmore sub-base barometer
U". S. Sign;il Service barometer.
XIX
-H 823.7
9C1.2
Bonneville shore-line, vicinity of Fillmore
Fillmore sub-base barometer . .
XXIII
— 19.4
941.8
COMPUTATION OF HEIGHTS.
415
Table XXIV. — ReducHon of liisulls to the Lake Shore Gauge Zero as a Common Datum — Continued.
Poiut.
Intermediate Datum.
From
Table
Difference in
Altitude
i-eferred to
Intermediate
Datum.
Altitude
above tlie
Lake Slmre
Gauge Zeio
Datum.
Feet.
Feet.
XXIV
XIX
961.2
893. 6
564 5
XXIII
,')99 1
butte.
XXIV
XIX
901.2
487. 1
(Jainp at White Muiiiituiii Spniit;
Fillmore sub-base barometer . .
— 474. 1
Provo shore-liue uu Wliiti_' Mmititaiii liiittc
Camp at "White Mountain
XXIII
+ 08. 9
556. 0
Provo tufa deposit on Taberiiaclo Butto lava
do
XXIII
+ 42. 9
530.0
outflow.
Filluiore aub-ba.se baiorneti-r
XXIV
901 2
XIX
— 17 3
943. 9
do
XIX
+ 1.2
963,4
Bouueville sboru-liue, base of South Twiu Peak
do
XIX
— 32.5
928.7
Salt Lake City Station (U. S. K. R.)
Mil fold Station. U.S. li. 11. extension
xxrv
52.4
Salt, Lake City Station
,XX1I
+ 707.5
759.9
Bonneville ahore-lino, vicinity of Milford (lat de-
Milfoid Station
XXIII
+ l.i2.7
912,0
termination).
Fillmore sub-base barometer
Canipuu Boaver River, vicinity of Milford
Filliiioru 8ul)-baao baronietor -
XXIV
XIX
961,2
742.6
— 218. 6
Camp (in Boaver River
Milford Station
XXIII
XXIII
+ 7.6
+ 152. 7
Bonuevillo ahoru-line. vicinity of Milfonl C-d i\v
902. 9
termination).
XXIV
961.2
885.2
Bonneville shore-line, vicinity of Milford (lid de-
Killiiioi-o snb baae barometer- .
XIX
— 76. 0
termination).
Fillmore sub-base barometer
Bonneville shore-line, 7 niilea south of Milfurd
XXIV
XIX
- 961.2
912.3
Fillmore sub-base barometer. .
- 48.9
Bnnnevillf sliore-line, 2 miles oast of Thermos
do
XIX
— 76.6
884.6
Bonmnille shoredine. 4 miles south of Thermos
do
XIX
— 48.7
9!2. 5
Bonneville shore-line. 7 miles south of 'i'licrmo.s
... do...
XIX
— 43.1
!I19, 1
Bonneville sbore-linr, 1 mile west of Antelope
do
XIX
+ :i8.7
999,9
Spring.
Bonneville shon*-Iine at Sulphur Sprinjis.
do
XIX
+ 4.5. 2
1000,4
Bonneville shoredine, west of entrauee to Pinto
do
XIX
1 214,1
117.5,3
Canyon.
Bonneville ahore-line, oaatof entrance to Meadow
do
XIX
+ 296.6
1257. 8
Creek Canyon.
Bonneville shore-line, west of entrance to Mea<lo w
Creek Canyon.
. do
XIX
+ 291.5
1255.7
Bonneville shore-lino, north of entrance to Shoal
Creek Canyon.
do
XIX
+ 265.8
1227.0
416 LAKE BOISNEVILLE.
ALTITUDES OF SHORE-LINES AND THEIR DIFFERENCES.
For cotivenieuce iu com par son, all tlie detcriniiied altitudes of points on the
Bonneville shoreline have been collected in Table XXV and arraiif;ed with reference
lo latitude, befjiiininfv with the most nortiierl.v. In addition to this a column lias
been i)repared S'^'inR tl^e "Inferred high-water level" of the Bonneville stage, with
its jjrobable error. The preparation of this column involves several considerations.
In tiie tirst i)lace, the shore record to which levels were run consistetl in each case of
a topographic feature which might or might not stand at the precise level of the cor-
responding water surface. In some cases there was reason to l)elieve that it was
hialier, in other cases that it was lower, and in order to obtain the altitude given in
the right-hand column, a correction was applied. To obtain the value of the probable
error of this altitude, two sources of error had to be considered, the eiror of instru-
mentation, or error of the leveling i)roper, and the error of the estimated correction
to the measured height.
In deciding upon the amount of allowance or correction to be applied to the
determined altitudes in order to obtain the iufeired high-water line, much attention
was given to the local characteristics of the shore line in the vicinity of each deter-
mined point. The effect of local conditions was the subject of sjjecial study by Mi'.
Gilbert, and the allowance for difference in altitude between the shore feature meas-
ured and the corresponding water surface was in each case based on his estiiiuite.'
With I'eference to the error of instrumentation, the attempt was made to deter
mine the general precision of each hypsometric method used. A probable error in
accord with such determined precision was assigned to eacih separate measnremenf,
and the probable error of each measured altitude was deduced from the combination
of the errors of the several steps on which the measurement was based.
The probable error ef the estimated allowance for the difference in altitude
between the topographic feature measured and the high water level was itself a mat-
ter of estimate oidy, being based upon considerations arising from Mr. (Jilbert's gen-
eral study of the subject.
The probable error of the collected altitude was deduced by combining, in the
usual manner, the probable erior of instrumentation with the jjrobable error of the
"estimated allowane(>."
In ascertaining the precision of the bar(unetric work, use was niaile of the long
series of simultaneous observations at Fillmore and Salt Lake City. Sixty indei)end-
ent comi)ntations were made of the difference in altitude of the two stations, each
computation being based on a single set of concurrent observations. A computation
based on the discrrepancies of the sixty results showed the luoliable error of a single
determination to be IrliS feet. The errors assigned to the barometric determinations
were estimated on this basis, allowance being made for distance and other special con-
ditions.
A part of the leveling work was dui)licated, and an examination of the records
of such duplicated work led to the belief that, as executed by u.s, a line of levels not
exceeding five miles in length nor 1000 feet in vertical range, need not be assigned a
'A (lisi^Mssiou of this siilijiTt will ho fouiiil in Cliaiilcr III of tliis volume, iinJer the ht'a<]iii<;s
" EmbaukiniMit Series" aud " Doteniiiiiatiou of Still-water Level," i)p. Ul-l'i'). G. K. G.
HEIGHTS OF SOORE-LIXES.
417
greater probable error than one foot. Locke's liaml level, when supported by a staff
and used on a steep hillside, was found to have a probable error of about one foot in
SOO feet of ascent.
The probable errors recorded in the following tables were obtained by combining
the estimated probable errors of measurement with the estimated probable errors of
identification of the plane of tlie ancient water surface. It is recognized that any
individual determination, not duplicated, msiy involve some gross error for which no
allowance is made, but if such errors exist their number is small.
Tablk. XW.—Coniptiralive Schedule of Jltit tides of Poiiils on the Boiinerille Shoreline.
Locality.
Description of Determined Point.
Di'terniint'd
Alliliulii
almve Iho
Lake Shore
Gau;lo ZiTo.
Iiiferreil
hiyli-water
level, above
Lake Shore
Gauge Zero.
Feet.
Feet.
Red Kock Pasa
Inner edge of a cut-terrnco
897.7
906 ± 4
.... do
933.7
933. 0
940+ 3
942+ 4
.... do
Kelton Butte
Crest of an enibnukmont
1024. 3
1019+ 3
1014.2
1050+ 3
AVniard.
do
976. G
985+ 3
971.1
981 ± 5
970.7
970.9
980 ± 5
979+ 5
Salt Lake Citv
Dous^laa. By first determination.
S-ilt, LaVe Citv
Inner edge of a ctit-tprrace back of Fort
Douglas. By .second determination.
970.2
984+ 5
I'Uick Kock ■
TiHier fdge of a cnt-toTrncu
1000. 3
1008+ 3
North ci.d of Aijiii Uauj^e..
Inner edgeof cut terrace. By first determi
nation.
1000. 1
1068 i 3
Nintli end of Aqiii UaiiL^o. .
Innei" edge of a «ut-ti*rr;n-n. By second ilt^-
tonnination.
lOOG. 0
1074+ 4
I'oiutof the Mmiiilain . ..
957. 4
1019.0
899.4
894. 0
911. S
893. G
943.9
902. 4
9)0+ 3
1014+ 5
902+ 3
902+ 5
938+ 8
902 i 15
953 + 15
971+20
do
do
Pavaiit Butte
Near outer edge of a cut-terrace
Middle of a cut-torrace ,
Outer edge of a out-terrace
B;ise of North Twin Peak. .
Base of South Twin Peak..
.. do.
928. 7
939+20
Milford ...
End of a V-embanknient. The elevation
given in the third columu is the general
900. 3
904 + 10
mean of the three determinations of the
point given in Table XXIV, weighting
the first at 5, the second at ■'J. and the
third at 1.
7 miles aouth of Milford ...
Outer edge of a cnt-terraco
912. 3
921 + ''O
2 miles east of Thermo=»
Middle of a narrow cut-terrace
884.6
893+25
4 miles aouth of Tliernibs .
7 miles south of Thermoa
Middle of a cut-terrace
912.5
919.1
921 ±25
927+25
do
MON I-
-27
418
LAKE BONNEVILLE.
Tablk XXV.— Comparative Schedule of Altitudes of Points on the Bonn.eville Shore-line — Contiuued.
Locality.
Description of Determined Point.
Det<-ruiincd
Altitude
aliove the
Lake Shore
<iauj;e Zero.
Inferred
liigh-waier
level, almve
Lake Shore
Gauge Zero.
.Viitf'Iopo Sprinj: (Lower
Escalantf Desert).
Middle of a cut-terrace
Feet.
999.9
1006.4
1175.4
12.';7. 8
1255.7
1227,0
Feet.
1008 ±30
1015 ±25
1175 ±35
1258 ±35
1256 ±35
1227 ±35
Outer edjje of a narrow cut-terrace
Outer edge of a delta t erraco
Pinto Canyon
Meadow Creek Canyon
(East of entrance).
Meadow Creels Canyon
(West of entrance).
SlioalCreeli Canyon (North
of entrance).
Outer edge of a delta terrace
Outer edge of a delta terrace
Tables XXVI and XXVII jiresent, in form similar to the arrangement ot Table
XXV, the deteruiinatious made ou the Provo and St.insbury shorelines.
Table XXVI. — Comparative Schedule of Allitiides of /"oin/.s oii the Provo Shoreliiie.
Locality.
Description of Determined Point.
Altitude
.above Lake
Shore Gauge
Zero.
Inferred
water level,
above Lake
Shore Gauge
Zero.
Toner edge of a cut-terrace
Crest of a bar ou ed"e of a della
Feet.
568.7
576.9
663.2
672.3
623. 6
040. 3
678.0
685.0
581.9
644.0
5fi4.5
556.0
530.0
Fed.
569 ± 3
577 ± 2
663 ± 3
672 ± a
024 ± 5
6t0± 4
679 ± 3
685 ± 4
580± 3
640± 5
553 ±10
530 ±15
Logan
Inner edge of a eut-tt-rrace
do
Willard
do
do
North endof the Aijui Range
Northendof the A(]ui liange
Point of the Mountain
Inner edge of a cut-terrace, by first determi-
nation.
Inner edge of a cut-terrace, by second de-
termination.
Croitofabar
Inner GiXge of a ciit-terrace — indistinct
Crest of uu enibankment
White Mountain Spring
Do
Line of calcareous tufa on lavaoutllow about
Tabernacle Butte.
Tablk XXVll. —Comparatire Schedule of Jltiliides of Pointii on the Stiinshury Shore-line.
Black Roek Cut-terraco.
North end of the A qui Range.
254. 3
332.7
254 ±3
333 ±3
FIEIGHTS OF SHOEE-LmES.
419
Tables XXVIII and XXIX are in general compiled directly from Tables XXV,
XXVI and XXVJI, and give tbe diflereuces in altitude of tlie higb-water lines of the
liinineville and Provo stages, and Prove and Stausbnry stages respectively. The
Siiowsville, Dove Creek, and Matlin results come direct from Table XVIIl.
Table XXVIII. — Diffen iivtn in Alliliidc of the IloniicriUe and Provo Sliorc-lim.'i nl furious Localitiex.
Locality.
Description of Point on Bonne-
ville Shore.
Description of Point on Prove
Shore.
Ditference
of Altitude.
Outor edj;e of a cut-terrace .
Inner edge of a cut-terraco . . .
do
Outer edge of a cul terrace
Inner edge of a cut-terraco
Cre.st of bar on edge of a delta
terrace.
Crest of an embankment -
Inner edge of a cut-terraco
.... do
Feet.
365+ 2
371+ 2
305+ 3
382+ 2
356+ 3
374+ 3
413+ 2
411+ 3
301+ 3
300+ 3
389+ 3
380+ 3
374+ 3
370 t 3
392 .^: 3
397+ 2
382+ 5
339 + 10
385+ 8
345+ 2
341+ 2
Fiankliu
WcU^viUc
Crest of an embankment
do
Kclton
rroinontorv
Inner edge of a cut-terrace
Crest of a bar
Outer edge of a cut-terrace
Inner edge of a cut-terrace
do
Matliu
Crest of a bar
Willani
Inner edge of a cut-terrace
do
North end Aqui Range -
Grantsvillo
... do
.do
Cre.st of an embankment ... . .
.... do
..do .
Point of the Mountain .
.. do -. ....
Crest of an embankment
Inner edge of a cut.terrace
Crest of an embankment
Outer edge of a cut-terrace
Cut-terrace (indefinite)
Crest of embankment on White
Mountain Butte-
Crest of an embankment
do
do
do
Fish Spring ,
Outer edge of a cut-terrace
Crest of a hav bar
Crest of an embankment ... .
do
Preuss Valley
(Middle series)
(South series)
Table XXIX. — Differences in Altitude of the Provo and Stansbury Sliore-lines at various localities.
Vicinity of
Nature of the Provo Shore.
Nature of the .Stansbury
Shore.
Piiference
nf Altitude.
Outer edge of a cut-terrace -.
Inner edge r'f a cut-terrace - . -
do
Feet.
310 ±3
380 (?)
346 1 3
Black Rock
North end of tbe Aqui Range
APPENDIX B.
ON THE DEFOKMATION OF THE GEOID BY THE REMOVAL, THROUGH
EVAPORATION, OF THE WATER OF LAKE BONNEVILLE.
By R. S. Woodward.
The following paragraphs contain an outline, with special reference to the Lake
Bonneville problem, of a general investigation of the form of the geoid as inlhienced
by local attracting masses of certain determinate forms. The fullest publication con-
stitutes Bulletin No. 48 of the U. S. Geological Survey, entitled On the Form and
Position of the Sea-Level. Some of the mathematical work appears in the Annals of
Mathematics, in Nos. 5 and 6 of Vol. 12 and No. I of Vol.3; and the principnl numer-
ical results with reference to an ice cap are abstracted in the paper by Messrs. Cham-
berlin and Salisbury on The Drifcless Area of the Upper Mississippi Valley, in the
Sixth Annual report of the U. S. Geological Survey, pages 291-298.
The form and position assumed by the surface of the ocean or the surface of a
lake at any time are determined by the contemporaneous distribution and velocity of
rotation of the earth's mass. Any change in that distribution or in that velocity of
rotation ius'olves, in general, changes in both the form ami position of the free surfaces
of all terrestrial bodies of water. Such surfaces are called level surfaces, or now more
commonly, equipotential surfaces. Mathematically they are always regarded as closed
surfaces, or as encompassing the earth, however limited their visii)le i)ortions i)re-
sented by isolated bodies of water may be. Thus, the sea surface is imagined to
extend through the continents, its position at any invisible point being the height to
which water would rise if permitted to flow through a canal from the sea to that
point.
Of the two factors which determine the form and position of the sea level at any
epoch, the distribution of the earth's mass is the more important. Indeed, the rota-
tion of the earth may be entirely ignored in computing the eflects on the sea-lev<^l of
such changes in the su[)erficial distribution of matter as are here considered.
It will be convenient in what follows to distinguish between the relative atti-
tudes of the surfaces of the sea or any similar equipotential surfaces at different
epochs by referring to them as disturbed and undistiubed surfaces. Thus, according
as we call the present sea surface uudisturbud or disturbed the past and future sur-
faces are disturbed or undisturbed. It will also be convenient to call any mass pro-
ducing such relative changes in sea level a disturbing mass.
421
422 LAKE BONNEVILLE.
In the paper referred to above it is sbowii that tlie efifect of superficial masses
of small maguitudo in comparison with the earth's mass iu distorting the sealevel is
expressed by the formula
« = — ^— , (I)
in which v is the elevation or depression of the disturbed surface with respect to the
undisturbed at the point where the potential of the disturbing mass is V;' V„ is the
potential of the disturbing mass along the line of intersection of the disturbed and
undisturbed surfaces, or the value of V where i'=:0; and g is the acceleration of
gravity.
The application of the above formula presents lu) <lif6culty except in the calcu-
lation of the potentials V and Vo, which are in some cases quUe complex quantities.
For one of the most important classes of cases, namely that in which the disturbing
mass is symmetrically disposed about a radius of the earth's surface, the ])0tentials
have been expressed in terms of integrals which may be readily evaluated for the
characteristic points of the disturbed surface. In this class of cases the disturbed
surface will evidently be equi symuietrical with respect to the axis of the disturbing
mass, and, disregarding the etfect of the rearranged water, the auiount of the disturb-
ance is defined by the following formula :
V
= 4-Jo -^-~,^-"'^V(W. (2)
Herein r has the same meaning as in ( 1 ), p is the density of the disturbing mass, p„. the
mean density of the earth, tt the number 3.14159 +, ft the angular distance of any
point of the disturbing mass from its axis, and fto is the angular radius of the border
of the mass or the limiting value of /?. The quantity I is a definite integral which
may be most briefly expressed thus —
r" /cos p
J 0 V cos p ■
COS ft \i
— ] dp when (x<ft
cos
(3)
/■' /cos H — COS /i \2 , , ^ ,
= I ( (In when a>ft,
, / 0 V^'os 2> — cos a I ^ ' '
wherein a is the angular distancie of anj- ])oint of the disturbed surface frotn the axis
of the disturbing mass, a and v are thus polar coordinates of the disturbed sea
surface.
The effect of the rearranged sea-water, ignored above, is simply to produce an
exaggeration of the type of surface defined by (2), ami this exaggeration may be
expressed by a series of rapidly converging terms (see §§ 20-24 of paper on Form and
'If Hi be an element of the (U.stiul)iiig mass aiiil r its dislaiice tVoiu the point in question, thi;
potential of the mass is the sum of all I lie iinotieuts '", or V ^ 3 '" . The non mathematical reader
)• r
shonld distinguish carefully between potential and attraction, the latter bcini; a dirivative of the
former.
DEFORMATION OF GEOID.
423
Position of the Sea Level), but for tbo small masses bere considered tbe snm of these
additional terms is iiisigiiiflcant. In all cases, indeed, tbe characteristic effects are
expressed by equation (13).
For lenticular masses of tbe type assumed iu the text, the thickness is given by
the expression
<p{ft)
0
sin'^i^X
sin" yjoj'
(3)
Here ho is tbo thickness along the axis of the
mass, /3 and fto have tbe meanings assigned ^
above and h is any positive integer. This for-
mula makes (p{/i) =/'oi or tbe mass of uniform
thickness when n is iufiuite. For other values
of n tbe mass will be thickest along its axis
and diminish in thickness more or less rapidly
as we pass from tbe axis to tbe border, or as /i
increases from 0 to ft,,. Some of tbe curves de-
fined by ('^) are shown in Figure 51. Tiie scale
for the sector ABC, representing a great circle
of tbe earth through tbe axis of a lenticular
lake basin, is 1:125,000,000 and the radial
scale for tbe curves ?i = 1, 3, 7 is exaggerated
about 5,000 times, the assumed value of /(„ being
1,000 feet.
For the particular value of (p{ft) given
by (3), equation (2) becomes
v = 3
.A
Fin. 51.— Crosa-sectiou of Ideal Lc-nticuhir Lake
Basins.
Scale for section of terrestrial spliote i^^ninson-
Rndicul scale for thickness of disturbing mass, or
«(^) =
\ sm" Jflu/
1000 feet.
7rp„
r' \y^m ift\'> nn \
(4)
If we represent the values of the definite integral in tiiis equation for points along
tbe border and at the center of the mass by S2 and Si respectively and denote tbe
corresponding values of v by V2 and »i respectively, we find
ih
hop
{ S2 - S, }
(5)
This expresses tbe difference in altitude of tbe disturbed surface at tbe center and at
tbe border of the disturbing mass. When, as in the present case, tbe disturbing mass
is water in a lake basin, we must substitute for /j tbe difference in density of water
and superficial rocks. That is,
p = 1 — 2.8 = — 1.8 approximately.
Finally, if we wish to ascenain tbe seiiaration at tbe center of tbe basin, due to
a change in the density of its contents, of eipiipotential surfaces which intersect along
424
LAKE BONNEVILLE.
the border, we have only to diflerentiate (5) refjarding (i'2— »i) and p as variables and
substitute for Zip the change in density of Mie contents of the basin. Thus, the sepa-
ration is expressed by
Tlie vaUies of S| and S2 in (•^) and (G) may lie found from the following oxpres-
n
b, = ^^ _^ J n sin ^/i„.
S. = ^ sin hft„ \ ., (~_^j + jy (,^ ^^^ (1 + sin^ }Ji,)
+ \
Rions
The march of the above functions Si and Sj and the corresponding values of
(v., — ?'i) and J (i'2 — lu) is illus-trated by the numerical results given in the table below.
The data for these results are the foUowiu" :
1000 feet, /y„ = arc of 1",
r, r.
IJ =~ LS',
zJp = -I.
The results in the fifth column show how niucli nearer to the center of the earth the
assumed lake surface is at the middle of the basin than at its border; and the results
in the sixth column show how much ashore trace at tlie middle of the basin would be
found to be above the contemporaneous trace at the border, by a line of spirit levels
run after the removal of the water.
TaBlk XXX. — Valncs skoiriiiy relative posUlnna of Lend Surfaces in a lake hasiii 140 miles in diameter and
of 1000 feet maximnm (axial) depth.
n
s,
Sj
s,-s,
1), — t),
^(i>2 — »,)
FMt.
Feet.
1
n. 00436
O.OOICI
0. 00^75
2.70
1. .-,0
2
. 0D.)82
.00:.'45
. 00337
3.31
1.84
3
. 00034
. 002DS
. OOJ50
3. 50
1.94
4
. OU0U.S
. 00333
. 00365
3. 58
1 99
0
. 011727
. 00359
. 00368
3.01
2.01
G
. 00748
. 00379
. 0036!)
3.62
2. 01
7
. 00761
. 00395
. 00160
3.62
2.01
8
. 00776
.00407
. 00369
3.02
2 01
9
.007^(0
.00418
. 003(18
3. Gl
2.01
10
.00793
. U0427
. 00366
3. .59
1.69
00
. 00(173
. 0U5S6
. 00317
3.11
1.73
ATPENDIX C.
ON THE ELEVATION OF THE SUEFAOE OF THE BONNEVILLE BASIN
BY EXl'ANSION DCE TO CHANGE OF CLIMATE.
By E. S. Woodward.
The folIowiDg problems were submitte<l to me by Mr. Gilbert:
(1) Ten lliiiusaiid years aj;i) tlio Kiiifacc, (mean) teiiiperatiire of the Boiiiievillo basil), wliieli had
been long ^'onstanf, was raised 10 F. and it Las been sinee nncbanjied. The linear exiiansiiin of the
subjacent material is .000,1101! perdei;ree F. ; tbe cnbic expansion .000,018. Horizontal dilatation bein"
prevented l>y interference, tbe total eiil)ic expansion was expressed in vertical dilatation. How many
leet was tbe surface of the groniul lifted ?
(2) Same as above for period of 100,000 years.
(3) Same as above for period of l,00O,00u years.
The cooling by coiuliiotion of a large s[)liere like the earth from an initial uiii-
(brm temperature, gives rise to cubictil contraction whose amount is assigned approxi-
mately by the following formula:'
V 71
zlV = Syrrhiea ^1 -
in which
r = the radius of the sphere,
u z= the initial unitbrin e.Kces.s in temperature of the sphere over that of the sur-
rounding medium,
a^ = the coelidcient of diffusion, assumed constant for the whole sphere,
e = tbe coetiticient of cubical contraction, assumed constant,
t = the titne after tlie initial epoch,
;r = 3.1415+.
This formula will apply to the earth for l,0()(),()O0,()0l» years subsequent to the
initial epoch witliout iiitioducing errors greater than those involved in the assump-
tion of constancy of a and e.
Conversely, the above formula will give the cubical expansion of a sphere, con
sequent upon being immer.sed in a medium which maintains a constant surface tem-
perature u degrees higher than tlie initial temperature of the sphere.
' Forcorapleto formula see Aunals of Mathematics Vol. Ill, No. 5.
425
426
LAKE BONNEVILLE.
If in the latter case wc suppose tbe total volumetric expansion to result in ver-
tical uplift, an eflcct wliicli would follow from heating the earth's crust if it behaved
under expansion like a liquid, the amount of the uplift will be expressed very closely
by the quotient of equation (1) divided by the area of the surface of the sphere. Thus,
calling the amount of the uplift z/r, we have
STir^uea
Ar =
n
inr^
= 2uea
il-
(2)
tJsing the year and the British foot as units, Sir W. Thomson finds a = 20.
With this value and with u = 10° F. and c = 0.000018, (2) becomes
Foot.
zJr=z 0.00406 V 7.
This gives the following values of Ar corresponding to several values of <:
1.
^r.
Tears.
10, 000
100, 000
1,000,000
Feet.
0.41
1.28
4.00
INDEX.
Page.
Aa at Ice Spring 323
Adams, J., lake rampirts 71
Adolescent coast lines. *53
Airy, G. B., tbeory of waves 26,29
Alg» 259
Allen, O. r>., analyses of Bonneville earths 200
analyses of Sevier Lake desiccation products. . . 226
analysis of water of Great Salt Lake 253
Alluvial cone and fault scarps, view 349
Alluvial cones, Bonneville Basm 91
Frisco Kango 92
Marsh Creek ■- HB
Lake Creek 185
aridity and 220
Alluvial fans 81
Alluvial terraces and fault scarps, Kock Canyon 344
American Fork 346
near Salt Lake City 349
East Canyon 352
Alluvial cone terrace 81
Altitudes and their determination 405
Altitudes of shore-lines 362,427
American Fork, deltas 155, 346
fault scarps 346
Analyses, tufa 168
White Marl and Yellow Clay 201
waters of City Creek, BearKiver, and L'tah Lake 207
Sevier Lake briue and desiccation products 226
water of Great Salt Lake 252
waters of Bear River and Utah Lake 254
Andrews. Edmund, theory of littoral transportation . 26, 41
subaqueous rid;;e3 44
Antelope I-land bar 240, 243, 410
Appalachian Valley 391
Arpii Range, fault structure 341
fault scarps 352
heights of shoredines 366,370,372
measurement of shore lines 412, 414, 417, 418, 419
Area, Great Basin 5
Bonneville Basin 20
Lake Bonneville at highest stage 105
Lake Bonneville at Prove stage 134
Sevier Lake 2i5
Areas, interior basins of Arizona, New Mexico, and
Texas li
various lakes 106
Great Salt Lake 243,244
Aridity and alluvial cones 220
Aridity of Great Basin, described 6
cause 10, 280
Page.
Arizona, interior basins 11
Pleistocene eruptions 337
earthquake 361
Arno Valley, Pliccene fauna 399,400
Arrow point, fossil 303
Artemia gracilis 258
Barometric measurement of shore lines 363,406
Barometric measurements, probable errors 416
Barrier, described 40
compared with other ridges 87
Bairy,W.C., tbeory of salt harvest 224
Bars. (See alao Bay bars) 48
Basalt Valley 219
Basaltic eruptions, Bonneville Basin 319, 325, 338
map - 334
Basin Ranges, type of at ructuro 5
of the Bonneville Basin 91
Basins, hydrogr-iphic 2
interior, of Aiizona, New Mexico, and Texas... 11
of the Bonneville Basin 122,222
Basaett, H., analysis of water of Great Salt Lake 251, 253
Bay bars, origin and character 48
Snake Valley 111,112
Tooele Valley , 131,132
Beach, origin 39
profile. 39,42,45
Bear River, deposits in Cache Valley. 163
gate of ITS
possible changes 218, 263
irrigation 250
Bear River water, precipitation experiments 206
analysis 207,254
Beaumont, Elie de, shore topography 26
limitation of tidal action 29
variation of beach profile 42
Beaver, fossil 303,394,400
Beaver Creek delta 166
Becker, G. F., cited 284
Beckwith, E. G., cited 14
Bellville Creek delta 162
Bench-mark at Black Rock, installation 231, 409
leveling 232
height 233,410
map -. 390
Benchmark at Farmington 409
Biinadou, J. B 18
Big Cottonwood Creek delta 165
Big Willow Creek moraines 309
Bipartition of lacustrine and glacial epochs 270
427
428
INDEX.
Pago.
Birds, fossil 303,304
nisoii, fossil 211
lilmk Kock, view of laku terraces i
lieiRht of shore-lines 365,370,372
niea!*iiieiuenl of shorc-linoa 412,414, 417,418,419
Hlack Kot;k beucb, iustallation 231,409
Unchnj; 232
hoight 233,410
map 3!to
Black Rock gauge, iuslallaiion 23 1 , 409
leveling 3:t2
Iifight 233.410
noord 233
lUuckfoot River, possible changes 219,203
lUacksnjitb Fork, superpoailion of embauktueuts ... 151
dt'ltas 162
lUake, William P., cited 15
Illoody Cauyon nioraiiios 313, 315
Bouiioville Basin, description 20
ninp of subdivisions 122
bistory 214,316
subdivisions 222
possible changes 262
Bonnevilb' beds (see, also, White Marl and Tello^v
Clitii) 188
llonnox ille, B. L. E., explorations 12
Buuuevillo fossils 209
Bonne vilbi Lake, outline at highest stage 101
area and depth 105
depth 125
authorities for map 125
outline at Provo stage 127,128
composition of water 204
large map (in pocket of cover.)
Bonneville sliore-Une, highest 91, 94, 97
general description 93
clilfs and terraces 107
V-embauknionts , 108
spits and loops 108
deltas. 109.153
embankment series Ill
uncertainty of still-water level 125
near outlet 174
on Pavant Butte 326,328
in Esc.ilanio Desert 362
deformation 365
height at various points 365
curves of equal height 3G8
synchronism .. 369
(See, also, Intermediate Hhore-lincs, Provo shore-
line^ and Stanshury shoreline.)
Box Elder Creek deltas 163
Braddock's Bay 50,63
Bradley, Frank H., observations on Lake Bonneville. 10
cited on ancient delta of Ogdcn River 93
cited on terraces in Marsh Valley 95
cited on highest shoreline 96
cited on dt-ltas 153
cited on i)utlet of Lake Bonneville 173
leveling at Ogden 412
Branchinecta 259
Brewer, W. H., cited 206
Brigham City, deltas near 163
Brine of Great Salt Lake 251
Bi ine of Se vicr Lake 226
Page.
Brine shrimp 254
Brodie, James, cited 270
Uriickner, Eduard, cit*'d 271
Burgess, M. F., leveling data 412
C.icho Valley, terraces 95,96
Tertiary lake beds 99
Bonneville Bay .' 102,178
del taa 1 59, 1 62
fault scarps 351
Call, R. EUswctrth, recent and fossil shells of Great
Basin 19,297
Bonnrville shells 210
Campbell, J. F., cited 270
Cedar Range 103,128
Cbadbtmrne, P. A . , cited 211
CIiamberlin,T. C, cited 272
Cbatard,T.M., analysis 207
Christmas Lake fossils 303, 394
Ciiurcb Lake 300
Cialdi, Alessandio, coast processes 26
tlieory of littoral transportation 41
City Creek deltas 164
City Creek water, precipitation experiments 206
analysis 207
Clarke, F.W., analyses 207
Clarkstor, fnult scarps 351
Clayton, .I.E., cited 348
CliiTs, formation by waves 34
classification 75
comparison 75, 77
Climate and interior basins 3
Climate and moraines 398
Climate curves 246
Climate of (ireat Basin 6
Climate of lake ejioeh, as inferred from fossil shells. 297
as inferred fritm fossil bones 303
as iiifeired from moraines 305
Climatic factors affecting lakes and glaciers 275
Climatic interpretation of lake oscillations. 265
Cloud-burst channels. 9
Coast lines, local phases 60
adolescent and mature. 63
simplification 63
of rising and sinking land 72
Cold, <-orrelation with buMiidity. 265
corrt'lation with <lepauperation of shells 300
Cnlm-ado Desert, ancient lake 15
Coi.e, alluvial. See AUunial cone and Alluvial/an.
Confusion Riiugo, fault scarp 353
Connm, P.E .cited 228
Coolidge, Susan, observation of oolitic santl 169
Cope, E. D., cited on Christ nins Lake fauna 303
defuiition of Eqnus fauna 394,400
cited on age of Eqnus fauna 397, 398
cited on Pleistocene climate 398
Corinne, height 411
Correlation by means of fossils, methods 398
Correlation of lakes with glaciers 265
Correlation of shore lines with sediments 188
Cottonwood Creek, deltas 165
moraines 305.300,046
fault scarps 346
niap 346
Coulee edge, compared with other cliffs 76, 77
INDEX.
429
Coyote, fossil 303,394,400
Coyott^ Spring, rhyolite 337
Cratei's, Ice Spring 32U
Pavaut 325,3.»8
Tabernaele 328,320
Funiarolo 332
Crescent crater 320, 322
doll, James, cited- 284
Crosby, W. O., theory of joint structure 213
Crust of the earth, strength 387
Cub Creek, delta 102
Clip Butte, view 54
looped embankment 169
profile of shorelines 1^8
shoreline measurements 372,412,419
Current, theory of wind- wrought 29
function in transporting shore drift 37
function in funning embankments 46, 47
function in tliL> biiihlingof houks 52
Curve of precipitation change for Great Basin 245,249
Curve of rise and fall of Great Salt Lake, annual 239
non-pe riodic 243, 240
Curveof secularclimalic change in BonnevilleBa-in. 2G2
Curve of temperature change for Great Basin 240
Curves of etiual height, Bonneville shore-lino 3C8
Provo shoreline 372
Curves of snow-fall and melting 289, 293
Curves, theoretic, of post-Bonneville deformation 374
Cnt-and-built terrace 30,40
Cut-terraces, mode of furmation 35
of Bonneville shore-line 107
of Prove shore-line 127,128
of Intermediate shore-lines 144
Cypris 210
Dana, Edward S., bulletin by 19
Darwin, G. H., cited 387
Datum fur gauges, map 390
Datum jioints connected with gauging of Great Salt
Lake : 233,409
Davidson, George, cited 10
D ii V i s, W . M . . e i ted 1 80
Dawk ins, W. B., Pleistocene mammals . 400
Dead Sea history and glacial liisLory 2G5
Death Valley 8
Deep C reisk Kange, faults 353
Deer, fossil 211,303,394
Deformation, crustal, by loading and unloadini: 3.'i7,379
of Bimnoville shore-line 'iG\ 308
of Prnvo slnire-lino 371, 372
duiing Prcivo epoch. 372
ipiestion of cause 373
curves of theoretic 374
nf geoid 421
of Bonneville Basin by expansion 42r>
Degradation clift" compared with other cliffs 75, 77
Degradation terrace, compared with other terraces 78, 81
De la Bcche, Henry T., writings on shore topography. 20
variation of beach profile 42
Delta terrace, compared with other terraces 84
Deltas, origin 65
internal structure 69, 70
of emergent coasts 74
of Ogden River 93
of Bonneville shore-lino 109
Pago.
Deltas, Provo shore-line 129
of Lake Bonneville 153
history deduced from 166
of Spanish Vork 343
of Weber River 349
Depauperation of lossil sheiks 299
De|>osition, littoral 40
Deposition of salts by desiccation, Bonneville
Basin 204.208,258
Rush Lake 2_'9
Depth of Lake Bonneville 125
Di-pths of lakes, table 100
Desiccation, deposition by. See Deposil'ion.
Desoi", E., limitation of tidal action 29
cited on subaqueous ridges 43
Diastrophism, defined 3
and interiiir basins 304
and Lake Bonneville 340
of Jordan and Tooele valleys 307
Diatoms 210
Differential degradation cliff, compared with other
cliffs 75,77
Differential degradation terrace, compared with
other terraces 78, 84
Discrimination of shore features. 74
I>i.-*placement. See I>iastfophism and Deformation.
DistiiUulion of basalt, map 334
Distribution of fault scarps, map 352
Distribution of wave-wrought shore features 60
Divides, shifting of 217
Douris, T., gauge readings 235
Dove Creek, sea-cliff near ]07
Bonneville embankment series 112, 114, 117, 120
Provo ombankment series 131
Intermediate embankments 137
map and view ]38
embankment interval 143
superposition of emhanknieitts 151
measurements of heights 372, 406, 419
Drainage system of Bonneville Basin 21
Drainage system of Great Basin 7
Drew, Frederic, alluvial fans HI
Dry Canyon, fault >carp 340
Dry Cottonwood Canyon, moraines 309,340
fault scarps 340
Dug way Range, ihyolite 338
Dunderberg Butte 335,330
Dunes ,S9
Dunes of gvpsum 'Z'S.i
Dunes on Sevier Desert 332
Dutch Point 53
Dutton,<'. E., eitedoneauseof aridity of Great Basin. 10, 280
cited on isostasy 388
Karth shaping 27
Karlli, strength of the 38?
Earthquake waves and joints 213
E irtli quakes ;iGO
East Canyon, fault scarps 3.')2
El Moro, Pleistocene eruptions 337
Elephant, fossil 21 1, 303. 304, 394, 400
Elevation of Bonneville Basin by expansion 427
Emergence, effect on shores 72
Embankment, compared with other ridges 87
Embankment series, Bonneville shore-line 111,369
430
INDEX.
Embankment serios, Provo sliore-liuo 131, 132
ErabankmentH, littoral 46
rhythmic 73, 137
i»f Bonni'villo Mbore-line 1U8
of I'rnvo Hliort'-lino 127, 131, 132
of InteinuMliato shore-lines 135
conipouml 144
calcareouM cement 107
Emmons, S. F., iuvestigation of Pleistocene lakes ... 17
cited ou hijjbest shore-lino 90
(;ite(l on Tertiary in Rush Valley 99
cited on Litt!« Cottonwood glaciers 305
Empire BlutT.i 50
Eiidlirh.F.M., cited. 2C8
Engelmann, Ilt-nry, iuveHtigalionof Lake Bonneville. 15
lionrieville shells 209
Eocene lake beds 90
Epcirogeny defined 340
Ephedra jrracilis 259
E' 111 i potential surfaces 421
Etiuus fauna, question of age 393
Erowion by waves . . 29
Erosion cliff, compared with other cliffs 75, 77
Erosion terrace, compared with other terraces 78,84
Eruption, recency of latest 324
Escalante Basin, map 122
Escalante Bay, depth 125
question of synchronism 369
Escalante Desert, barometric measurements 362,406
heights of shore-lines 366, 415, 417, 418
Escalante Lake, theory of 363
Escalante, Padre, explorations 12
Sevier Lake 224
Evaporation formula 285
Evaporation rate in Great Basin 7
Expansion as a cause of post Bonneville deformation. 377, 427
Experiments in precipitation of sediments 205
Falsan, A., cited 271
Fans, alluvial 81
Farmiugton, installation of lake gauge 231,232,409
height of gauge 233,410
record of lake level 234
observations of lake changes 240
fault scarp 349
bench-mark 409.410
Fault scarp, compared with other cliffs 76, 77
Fault scarps, of Bonneville Basin 3t0
map showing distribution 352
general features 354
tlates of foi-mation 356
relation to *'arth<iuakes 361
Fault terrace, cornpan'd witli other terraces 83, 84
Faults of Jordan and Tooele Valleys 367
Fauna, Eijuus 393
Fauna of Great Salt Lake 258
Faye, 11. , cited 387
Felix. J., Pleistocene lakes of Mexico 402
Fetch of waves 43.107
Fetch of waves on Lake Ontario 53
Fillmore, volcanic field near 320
height of Bonne vile shoreline 366, 417
barometric station 406, 415
Fish Spring, fault scarp 353
shore-line measurements 372,412,419
Page.
Fisher, O., cited 388
F'ive acre Creek 174
Fleming. Sandford, on process of littoral transporta-
tion 26
on Toronto Harbor. 53
on retreating embankment 55
Flow of solids 383
Fluminieola fusea 302
Folded strata under Logan di-Ua 162
Fort Douglas, fault scarp 347
measurements of shore-line 362, 412, 413,414
height of Bonnevillo shore-line 365,417
Fortieth Parallel Exploration, investigation of Pleis-
tocene lakes 17
Neocene lake beds 99
credit to maps 126
survey of Great Salt Lake 230
map of Great Salt Lake 243,244
Fossil Lake 394
Fossil mammals and iSonneville climate 301
Fossil shells, evidence as to Pleistocene climate 297
depauperation 300
measvirementa 302
Fossils of Christmas Lake 394
Fossils of Lake Bonneville 209
Fossils of Lake Lahontan 395
Fox. Jesse W., leveling at Black Kock 232
FranUland.E., cited 284
Franklin liutte, discrepant shore records 124
heights of .shorelines 365,370,372
measurement of heights 412,413,417,418,419
Fremont, J. C., the name Great Basin 5
explorations 12
tufa near Pyramid Lake 13
Antelope Island liar 241
Fremont Island terraces 13
Frisco Jlange, V-bars 58
alluvial cones and shore-lines 92, 93
Fuaiarole Butte and lava bed 1 82, 3o w
Gale, L. D., analysis of water of Great Salt Lake . . . 2-i3
Gannett, Henry, cited ou Bear River drainage 218.219
altitudes 364
Garfield Landing Gauge, installation 231,409
renewal 232
height of zero 233,420
record 235
Garn, E , Lake Shore gauge 231,234
GastaMi. cited 271
Gate of Bear River 178
Gauging Great Salt Lake 2^0,409
Geikie, Archibald, cited 272
Geikie, James, cited 271,274
Gentile Valley, terraces 95,96
alluvial depo?iit3 103
Geoidal deformation 376,421
George's ranch, embankment series 112, 113, 114
auuient delta near 166
Gervais, Pliocene mammals 400
Glacial epochs, correlation with lacustrine epochs .. 263
num))er of 270
Glacial history of Great Basin bipartite 318
Glacial Period. See PUintocme.
(Jlacial streams, deflection of 315
Glaciated districts of the Bonneville Basin 374
INDEX.
431
Page.
Glaciation and aolar radiation 283
Gleu Iloy, ancieot shores aili)lencent 65
Gouilfelloff, George E., Sonora onrtliqiiake 361
Gouseborry Creek n7
Gopher. fo3sil 303,304
Gosiiite Ranjie, fault s*^ sir p 353
Graces, Padre 12
Graiul Canyon of the Colorado, vohirae 301
Giauite Kock, canyons and .shorelines 9 J, 03
Giants ville, map of shore embankmeuts 131
lateriueiliato e.nibankiuents ...135,139,143
traditional history of Great Salt LaliO 211
lueasuroment of shore-lines 372, 408, 410
Groat Basin, described .-- 5
ami its Pleistfieene Likes, map 6
climate 6
vegetation 9
cause of aridity 10
compared with interiorbasinaof othercontinenta. 12
history of exploration 12
minor basins 20
climare curvea 246
recent and fossil ahella 297
mountain structure 340
Pleistocene climate 398
Great Basin Division, organization and work xvii
field work on Lake Bonneville 18
publications 19
Great Britain, Pleistocene fauna 390,400
Great Salt Luke, evaporation rate. 7
view on shore 35
map of hydrographic basin 122
oolitic sand 169
surveys 230
depth 230
gauging 230, 409
recorded rise and fall 233
annual rise and fall '- 239
traditional rise and fall 239
changes in area 243
corapar.itive map 244
cause of rise and fall 244
future changes : 250
saliuo contents 251
sources of saline contents 254
rate and period of salt accumulation 255
fauna 259
position on plain 372, 384
Great Salt Lake Desert, lacustrine origin 214
surface 222
view of lost mountains 320
Gr.at Valley of Tennessee, volume 391
Greeley, A. AV., cited 7
Gypsum play a and dunes 223, 320
ILule of Kock Canyon faults 345
Uiigue, Arnold, investigation of Pleistocene lakes.. . 17
cited un highest shore-line 96
Hand level 411
ILuiu, Julius, cited 284
Hayden, F. V., observations on Lake Bonneville 16
cited on Bonneville beds 188
Bonneville shells 209
Hayden Survey, Neocene lake beds 99
Hector, James, cited 361
Pago.
Height differences, Bonneville and Provo shore-lines. 372,419
Height of first water mnximuni 199
Heights of IJunnevillo slmrelinr, tables 365,417
Ht'ights of Provo shore-line, tables 370, 418
Heights of shitr.'-line.*, 362,405
Ileury, I). Fiiriand, evjii)orati(m from LakeMichigan. 7
Henry, Jo.seph, promotion of research concerning
Great Salt L:iko 231,240
Henrj' Mountains, volume 390
High Creek, delt I 163
Hind. H. Y., chart of Toronto Harbor 54
History and seijuenceof Bonneville shore-lines 169
History of Bonneville Basin 214
History of Bonneville oscillations 259
History told by deltas 166
History tuld by River Bed and Leniington sections. . 197
Hitchcock, Edward, classification of stream lenacea. 80
Hitchcock, Charles H., explanation of lake ramparts. 71
Hobble Creek, deltas 165
fault scarps 344
Holmes, William H., sketch of shorelines on Oquirrh
Range i
sketch of fault scarps 348
Honey Lake 300
Honey ville, fault scarp 351
Hook, origin and character 52
on Lake Michigan, view 52
at Willow Springs 145
Hopkins, power of currents 41
Hoiiznntaiity of shorelines 88
Horse, fossil 303,394,400
Hot Springs, near Fumarole Butte 333
near Salt Lake City 349
near village of Bonneville 350
House Range (see also Fish Springs) 353
Howell, Edwin E., field work on Lake Bonneville 17
cited on highest shore-line 96
cited on deltas 153
cited on outlet of Lake Bonneville 173
measurement of shore-lines 362
theory of Escalante shore-line 363
shore-line in Escalante Desert 370
Hoxie, R. L., survey of Sevier Lake 225
Hualapi Valley 11
Humidity, correlation with cold 2G5
local, in relation to glaciation 278
law of vertical distribution 284
Hungerford, E., welding of snow 290
Hunt'sranch 174,178
Hydrographic basin. See Basin.
Hydrography of Bonneville Basin 21
Hydrography of Great Basin 7
Hydrostatic law in orogeny 357
U^ psometric data 405
Hyrum, delta terraces 163
Ice Spring 325
Ice Spring craters and lava field 320
Ice Spring craters, view 322
Ice Spring, fault scarps 325
Ice- wrought shore ridge 71
luter-Bonneville beds 192, 194
Inter-Bonneville epoch 261
Intf rior basins, causes 2
in Arizona, New Mexico, and Texas 11
432
INDEX.
Page.
Intermodiato Hhorn-linea, description 135
discussion of cmbaukmuiits 137
cut-terraces , 144
Inyo earthquake 301,362
Irri<:ation and Great Salt Lake 2\Q
Irrigatinn and Sevier Lake 227,250
Islands nl" Likii lioiuieviUe, miiin body 102
Sevier body 10'>
Isoatasy 387
Jiimiesou, Tbomaa F., cited 265
Johnson, Willard D., field work on Lake Bonneville. 18
map of bay bars iu Snake Valley 112
survey of White Valley Bay 126
map of I^of;au River delta terraces 160
map of KimI Kock Pass. 174
map of Old liiver Bed 182
map of portion of Old River Bed 194
exidoration of Sevier Lake salt beds 225
map of Sevier Lake and salt beds . 227
Joint atrtictnre . 211
Jones, Marcus E-.iiauging Groat Salt Lake 232,237
Jordan Kiver, Tertiary lake beds 99
irrigation 250
anal^-ais of water 254
Jordan Valley, diastrophism 307
Joidati- Utah Bay 103
Juab Valley Bay 103
Juab Valley, fault scarps 343
Kamas Prairie, change of drainage ,... 218
Kame.s, cou)i)ared with other ridgea 87
Kanab Creek, I'leistoceue eruption 337
Kanosh, measurement of height 408,415,417
Keller, H., on littoral processes 26
Kelton Butte, view J08
discrepant .shore records 124
heights of shore-lines 365, 370,372
measurement of f*hore-lines 400,419
King, Clarence, aeknowledgmi iits to xv
investigation of Pleistocene lakes 17
cited on highest shore-line yc
Eocene near Salt Lake City 100
citetl on correlation of sedimentsand shorelines. 189
fossil mammals 2!1
brine of Croat Salt Lake...- r.52, 254
cited on correlation of lake epochs with glacial
epochs 267
cited on ;;i.u'iation and heat 284
tlieory of Esi-alante shore-line 363
Ring Survey. See Fordrth Parallel Exploration.
K noli Spi ing, fault sca?p 353
Knowl ton's ranch, fault scarji 352
La Sal. Sierra, volume 390
Lagging of lakes behind glaciers 314
Lahontan llnsin. conipletii dusiucation ....: 258
Lalumian mamtnalian fauna 395
Lake basins 2
Lake beds 188
Lake beds intorslratilied with delta gravels 150
Lake Bonneville. See Bonneville Lake.
Lake Creek 185
Lake formerly in Colorado Desert 15
Lake rampart, mode of forma tiou 71
Page.
Lake rampart, compared with other ridgoa 87
Lake ridges iu Ohio 43,44
Lake shores, topographic features 23
Lake Point, fault scarp 35*^
Lake Shore gaug ■, installation 231.409
connoction with other gauges 2'Ai
litught 233.364,410
record 234
Lakes, Plei.stoceue, of the Great Basin, map- 6
of Great Basin 8
earlier than Bonneville 98
table of dimensions 106
correlation with glaciers , 265
Land sculpture 27
Landslip cliff, compared with other cliffs 77
Landslip teirace. compared with other terraces 83.84
Lartet, Loui.s, cited 205
Lattimore, S. A., analyses of Sevier Lake desiccation
y>roduets , 220
Lava field, Ice Spring 320
Pavant Butte 328
Tabernacle 329
Furaarole 332
Lava, liquidity 322
Lee, C. A,, lake rampaits 71
Leevining Creek, glacial moraines 312
Leniington, geologic section 192
record of first water maxiiniim 19!)
height ot shoreline 36'.
measurement of heights ...411, 412, 414, 417
Lenk, 11., Pleistocene lakes of Mexico 402
Level of still water 122
Leveling, account of work 304,411
probable error 417
Limuiiphysapalustris 300, 301
Little Cottonwood Creek, ancient delta 165
moraines 305,306,340
fault scarps 34©
map 340
Lit(le(iull Lake yoo
Littoial deposition , 40
Litloral erosion 29
Littoral topoijiapby 23
Litttnal trausjiortation 37
Llam;is, fossil 303,391,400
Loading, unhiadiiig, and tlefnriuation 357,379, 421
Loew, t»scar, analysis of Sevier Lake water 220
Logan, deltas if,ip
map of deltas inu
view of del [as 102
I'.iitlt seatp 351
heights of shore-lines 365. 370, 372
measurement of heights 411,412,413,417,4:8.41!)
Lone Pine, tarthipiake 361.302
Loops, origin ami eharacler 55
outline maps 5g
of Bonneville shore-line 109
Lost mountains 215, 320
Lower River Bed section 189
Lyell. Charles, method (.f Tertiary clas8t6cfttion 39H
cited on principles of e(u relation 401
Main body 101,122
Major, C. I. Forsyth, Pliocene niamm.ils 4O0
Malade Valley Bay 102
INDEX.
433
Page.
Mammalian fossils, from Eonnevillo beds 210
and Bonneville climate 303
from Christinas Lake 394
Map of Lake Bonneville, autborities 125
Marcet, W., brinoof Great Salt Lake 254
Markatjunt Plateau, Pleistocene eruptions 336
Marsh Creek, description 174
alluvial terrace 175
lower course 176
alternation of tribute 178
fault scarps 351
Marsh, O. C, cited on Equus fauna 393, 395
Marsh Valley, terraces i'5
general features 17G
Matching 399,402
Matlin, Tertiary lake beds 99
measurement of heights 372, 40C, 419
Mature coast lines 03
McGee.W. J., field work 18
oolitic aand 169
cited on number of glacial epochs 272, 274
cited on deflection of glaciers 315
Equus fauna 393
McKay, Alexander, cited 361
Meadow Creek, measurement of heights 408,415,418
Measurements of shore-line heights. 362, 405
Melting curve 289, 293
Mexico, Great Valley 402
Michigan Lake, evaporation 7
subaqueous ridges 43, 44, 45
view of bay bar 48
bay bar 50
hook at Dutch Point 53
Mil ford, height of Bonneville shore-line 365
raeasurement of heights 408, 411, 412, 415, 417
Mill Creek, moraines 311
Miller, Hugh, classification of stream terraces 80
Miller, Jacob, Farmington gauge 231,234
rise and fall of Great Salt Lake L'40
soundings on Antelope Island bar 211
Mimbrcs Basin 11
Mitchell, Henry, formation of beaches 26
Mitchell, John T., gauge observations 231,233
Miter Crater 321, 322
Mohave River 8
Molluflks, from Bonneville beds 209
and Bonneville climate 297
from Christmas Lake 395
Mono Lake, observations by J. D. AVhitney 16
Mono Valley, shore-lines and moraines 306, 311
Pleistocene eruptions 337
Montanari, theory of littoral transportation 41
Montpellier, Pliocene fauna 399, 400
Moiaine terrace, compared with other terraces 81, 84
Moraines, compared with other ridges 86,87
and ancient shore-lines. 305
and fault scarps 346
and climate 398
Morgan Valley. Tertiary lake beds 99
bay of Lake Bonneville 103
fault scarp 351
Mountains, of Bonneville Basin 91
view of buried 320
growth of 359
Muddy Pork, deltas 162
MON I 28
Page.
Murray, John, cited 12
Musk ox, fossil 211, 303
Mylodon sodalis 391
Neocene and Equus faunas 393
Neocene geography of Bonneville Basin 214
Neocene lake beds 99, 173
Nell, Louis, survey of Sevier Lake 225
New Garfield gnage 232,233,237
New Mexico, interior basins 11
Pleistocene eruptions 337
New Zealand, earthquakes 361
Newberry, John S., cited on number of glacinl epochs 272, 273
Nomenclature, geologic 22
Ocean currents in relation to glaciation 281
Ogden, altitude 3tJ4
height of Bonneville shore-lino 365
measurement of shore-lines 411,412, 413,417
Ogden Canyon, fault scarps 350
Ogden Piver, ancient deltas 93, 163
Old River Bed, map of V-embankments 58
description 181
map 182
lower section 189
upper section 194
geologic map of portion 194
Ombe Range, Tertiary lake beds 99
island in Lake Bonneville 102
Ontario Lake, headlands and bay bars 50
fetch of waves reaching Toronto 53
simplification of coast-line 63
distribution of mature and adolescent coasts ... 65
Oolitic sand 169,252
Oquiri h Range, view of lake terraces i
fault scarps 352
Oregon, Equus beds 394, 397
Orogeny discriminated Irnm epeirogcny , ... 340
Oaar, compared with otlier ridges 87
Otter.fossil 303,304
Outlet channels, characters 171
relation to shore-lines 186
Outlet of Lake Bonneville, description 171,173
literature 173, 182
map 174
view 176
question of earlier 1 80, 216
Owen, Fred. D., general assi.'itant 18
sketch of head of Tooele ^nlley 96
Owen's Valley, earthquake 361, 362
Ox, fossil 303
Packard, A. S., cited on Old River Bed 182
fauna of Great Salt Lake 258
Pahoehoe, Pavant Butte 328
Tabernacle Butte 330
Paleoutologic evidence on ago of Equus fauna 397
Paleontologic methods of correlation 398
Parallel Roads of Glen Roy 65
Park. John R., gauging Great Salt Lake 231, 409
Park Valley Bay 102
Pass between Tooele and Rash valleys, description 52, 97
map of hook 58
view 96
map 138
434
INDEX.
Pass between Tooele and Hash valleys, saperposition
of embankments
ancient river
Pavant Butte, descnption
view
height of Bonneville Hhore-liue
measurement of shore-lines -108,
Pavant Kange
Pa.vsoii, di'lta near
Peale, A . C, observations on Lake Bonneville
cited on shoreline higher than the Bonneville ..
cited on outlet of Lake Bonneville ^
cited on age of Bonneville beds
Penck, Albreeht, cited
Physa ampullacea
Physa gyrina
Physiographic evidence on ago of formations
rhywingraphy
Pilot Peak, terraces
Pink Cliff formation on Sevier liivcr
Pinto Cauyou, measurement of heights 408,
Plant, fossil
Playa de los Pimas
Plaj'as of the Bonneville Basin
Pleistciceue, shortest of the periods
lakes, map
name preferred to Quaternary
climate
volcanic eruptions 323, 326, 330,
winds
Eqiius fauna
two uses of term
mammalian fauna, Great Britain
lakes, Mexico
(See, also, Bonneville beds. White Marl, and TeUo^v
Clay.)
Pliocene and Equus faunas
Pliocene fauna of Aruo Talley
Pliocene fauna of Montpellier
Point of the Mountain, lu-.tn of V-bar
sca-elitf
iiue(|ual I'liibankuK-nts
piolilu uf omhankuR-nts
heights of shore-lines 365,
measureuient of shore-linos 411,412,414, 417,
I*noU', Henry S., obsei-vatious on Lake Bonneville. . .
Portage, didta near
Portnenf lliver, terraces
lower canyon
in Marsh Valley
possible chiingos
Post -Bonneville history
Powell, J. W., acknowledgment a to
cited on yonth ()f high mountains
Powell Survey, fiild work on Lake Bonneville
gauging Great Salt Lake
Pratt, John H., cited
Pre- Bonneville history
Piecipitati(m and interior basins
in Great Basin
secular curve for Great Basin
Precipitation of sediments. expL-riments
Prenss Lake
Preiias V:illey, V-hars
map of east side
149
184
325
328
366
415,417
319
165
18
94,95
173
267
271
300
301
396
27
144
99
415,418
210
11
222
1
6
22
265
336, 338
332
393
395
399, 400
402
393
399, 400
399, 400
58
107
123
138
370, 372
418,419
16
16ii
95
96
176
219
222
XV
350
18
230, 409
387
214
4
(i
245, 246
205
2J4
58, 121
92
Pago.
Preuss Valley, discrepant shore records 124
maps of embankments 136
embankments 137
profiles of embankments 138
interval between embankments 141, 143
double series of embankments 152
record of tirst water maximum 109
measurement of heights 372,412,419
Probable errors 4 16
Profiles, Bonneville Bay bars 116
Provo shore-line 132
Intermediate embankments 137, 138
Promontory Mountain, an island in Lake Bonneville. 102
at the Provo stage 128
heights of shore-lines 306, 370, 372
measurement of shore-lines 412,413,417,418, 419
Provo epoch, displacements 372
Provo River, sucieut deltas 153, 165
change of course 218
Provo shore line, north end Oquirrh range, view i
origin of name. 120, 153
outline and extent 127
later than Bonneville shore-line 127
cut-terraces 128
deltas 129,153
underscore 130
embankment series 131
area included 134
map 134
tufa 167
on Pavant Butte 326
on Tabernacle lava field 330
altitudes at various points 370,418
deformation 371
curves of equal height 372
Publication of work of Great Basin Division XVII, 19
Quaternary. (See Pleistocene.)
Kailroad altitudes 411
Kainfall, interior h.isius aiul 3
of Great Basin 6
secuhir curve f^r Great Basin 245.246
Uanipart, mode of formation 71
comparctl with otlu^r ridges 87
Kamsey, precipitation of sediments 20<i
liankine, W. J. Mc<i., theory of waves 26,29
lied Uock Pass, Bonneville mitlet 173
question of pre- Bonneville outlet 216
height of shor»'-liue 3(15
moasurenieTit of heights 411, 412, 417
Ueilding Spring, view of shore t<'rrace Il'tt
Ueindrrr, fossil 211
Uelalive huiiiiility, Great Basin 6
law of vertical distribution 284
Reservoir Butte, map of embaukuienta 58
description 110
superposition of embankments 148
nuip 148
view 148
tufa 169
Rhyolitft 337
Uhythmic embankments, conditions of formation. . . 73
of Lake Bonneville 137,141
Richthofcn, F. von, on littoral processes 26
INDEX.
435
Page.
Eichthofen, F. von, on characters of a senile coast. .. 64
Ricksecker, Eugene. 18
Ridge, 8ubaqueon8 43
Rid;;es, classification and comparison 86
Rigidity of earth's cr .st 358,387
Kiver Bed. (See Old River Bed.)
River Bed section, lower 189
u])per - 194
River water analyses 207,255
River nioutb bars 49
Rivers, ancient 171.181,184
Rivers of Bonneville Basin 21
Roan Mountain, volume 390
Rock Canyon, deltas 105,344
fault scarps 344
Routes of e*'olo^ic exploration, map 18
Rush Creek, moraines 313
Rush Lake, remnant of Lake Bonneville 14
map 138
inanold rivercUannel 184
history 228
Rush Valley, Tertiary lake beds 99
fault scarps 352
Russell, Israel C, field work on Pleistocene lakes. . . 18
publications on Pleistocene lakes 19
cited on cut-and-built terrace 30
cited on subaqueous ridges 44
photograph of bay bars 48
photograph of hook 52
contributions to Bonneville map lliO
cited ou American Fork delta 155
cited ou disturbed strata under Log-in delta 161
experiments in precipitation of sediments 205
cited on deposition by desiccation 209
observations on joint structure ... 212
gypsum dunes 223
collection of Sevier Lake salt 225
leveling at Black Rock 232
desiccation of Lahontan Basin 258
Lahontan history 264
cited on history of Lahontan climate. 267
Lahontan fauna 297
Christmas Lake beds 303.394
cited on history of ilono Basin 306, 311
cited on deflection of glaciers 315
map of Fillmore volcanic district 320
fault scarps of Great Basin 341
salt deposited from Great Salt Lake 257
Equus f luna 393
Rus-sell, J. Scott, theory of waves 26,29
Russell, Thomas, cited on evaporation in Great Basin. 7
Salinity and depauperation 301
Salt Creek delta 165
Salt deposit, Snake Valley 223
SeviL*r Lake 225,22(r
Great Salt Lake 257
Salt Lake City, Tertiary near 100
The Bench 164
fossil musk ox 211
fault scarps 347
earthquake prophesied 362
measurements of shore-lines 362, 412,413, 414
height of Bonneville shore-line 365, 417
Page.
Salt Lake City, barometric base station 400, 413, 414
Salt of Great Salt Lake 253
San August in, Plain of 11
San Francisco, temperature curve 246
San Francisco Mouulaiu, volume 390
San Francisco I'lateau, Pleistoceno eruptions 337
San Jose Kivtir, Pleistocene ertiptions 337
Siinford, W.A., Pleistocene manunals 400
Sautaquin, height of sbore-lino 'lO.^
measuroiuuut of shorc-Uuo 411, 412, 414, 417
Savage, C. R., photograph of Sheep Rock 35
Scarboro Cliff 54
Schott, Charles A., tables of precipitation and tem-
perature 245,247
Scirpus 210
Scoriai, Ice Spring 323
Dunderberg Butte 336
Sea level, dt'formation 421
Sea-cliff, origin. 34
compared with other clififs 77
Sea-cliffs, view on Oquirrh Range I
of Bonneville shore-line 107
of Provo shore-line 129
Sections of Bonneville beds 189
Sections of Sevier Lake salt bed 225
Senile coast 64
Sevier Basin, map 122
Sevier body of Lake Bonneville, described 104
depth 125
Sevier Desert, volcanic districts 319
rhyolite 337
SevierLake, description and history 224
salt bed 225
map 227
Sevier River, ancient deltas 166
shifting of divide 217
Shasta, volume of Mount 390
Sheep Rock, view 35
map 390
Shells, Bonneville 209
of Bonneville- Lahontan area 297
Christmas Lake 395
Shoal Creek, measurement of height 408, 415, 419
Shore deposition 46
Shore drift defined 38
highway of , 39. 40
method of accumulation in embankments 46
wasteof 39.40
Shore features, description 23
distribution 60
discrimination 74
Shore wall 71
Shore-line, highest 94
faulted 362
Shore-lines, ancient, in Ohio 43, 44
detection and tracing 88
of Lake Bonneville 90
on Frisco Range 92
on Granite Rock 92
perishable 101
and outlets 186
correlation with sediments .--. 188
near Salt Lake Citv, vii'W 348
ancient, of Christmas Lake 394, 396
436
INDEX.
Page.
Shore-lines, measuromen I of hcij^hta 405,416
Shores, topographic featiire.sof 23
adolesceut aurl luaturo 63
Sierra la Sal, volume 390
Sierra Ni-vada, Pleistocene eruptions. 337
earthquake and fault scarps 361
Siurra Nevada glacier;^ aud Mouo Lake 300,311
Sigual Service, cited on cliniatu of Great Basin 7
observations at Salt Lake City 400
Simpson. J. H., (diservaticm of ancient shorelines. . . ir>
Skull Valley, embankment aeries 112,113,122
Shith. fossil 303
STiiitli, R. II., barometer ohse.rver 407
Smitliliold Creek, delta , 162
Snake Valley, map of V-bars 58
bay of Lake Bonueville 104
V-embaukmeiits 108
embankment series 111,112
salt marsh 223
fault scarps 353
Snowfall Curve 289, 293
Snow-plow, map of V-bar 58
embankments. 137
map and view 138
embankment intervals 141,143
supei'ijositiou of emb nkmenta 147
measurement of shore-lines 372, 412, 419
Snows ville Valley, river channel 185
Bonneville beds 191
fault scarp 351
measurement of shore-lines 406,419
Sodium sulphate, precipitation fromGreatSaltLake. 252
Sonora, eaithquake 361
Spanish Fork, deltas 153,165,343
fault scarps 343
Spirit-level measurements 364,411
Spits, mode of formation 47
of Bonneville shoreline 108
near Grants ville, map 134
Spring: Creek, deltas 162,168
Stansbury, Howard, cited on shores of Lake Bonne-
ville 13
map of Rush Lake 228
survey of Great Salt Lake 230
map of Great Salt Lake 243,244
brine of Great Salt Lake 251,254
Stansbury Island bar 241,243
Stansbury shore-line, described 134
tufa 167
bypotUetic explanation 186
height 418
Stelling, formula for evaporation 2S5
Sternberg, C. H., collection of fossil bones 303
Stillwater level 122
Stockton, shore-lines near 52
V-bar 58
view of shore-lines 97
IntermedialL'ombankmonta 137, 138, 149
map 138
height of shore-lines 365,370,372
measurement of shore-lines 412, 414, 417, 418, 4! 9
Stoppani, A., cited 271
Strachey, Richard, cited 2S4
Stream Cliff, compared with other cliflfs 75, 77
Page.
Stream terraces, compared with other terraces 79.84
claaaiticatinn 8U
Sub-Appenine fauna 397,399
Subaciiumus ridge 43
Submergence, effect on shores 72
Sulphur Springs, mea«uroment of 8horc-lino.366, 408, 415, 418
Superior Lake, bay bars 51
Survoy of the Rocky ilounlaiii Region, fiehl work on
Lake Ilonuevilh) ]8
gauging Great Salt Lake 230,409
Survey of the Territories, Neocene lake beds 99
Surveys West of the lOOth Miaidiaii, investigation
of Lake Bonneville 17
map of Rush Lake 228
measurement (»f Hhoreline 362,414
Synchronism of Bonneville shore-line 309
Tabernacle crater and lava 6eld, map 328
view ^ 328
description 329
Talmage, J. E., analyses of water of Great Salt
Lake 252, 253
Taramelli, cited 271
Tavaputs Plateau, volume 390
Taylor, volume of Mount 390
Teconia, height of Bonneville shore-line 365
measurement of height 411,412, 417
Temperature, secular curves for Great Basin 246
and humidity . 265
relation to glaciation 276, 283
relation to growth of mollusks 300
Temperatures of fumaroles 333
Temperatures of hot springs 333
Terrace Crater 322
Terrace Mountain, spits of Bonneville shore-line 108
Provo embankment series 131, 133
shore-lino measureuieuts 372
Terraces, north end of Ofiuirrh Range, view i
wave-cut 35
cut and-huilt 36,40
wave-built 55
classification 78
comparison 84
of disputed origin 95
of Provo shoreline 127, 128
Tertiary. See a.\so Keoccne and Pliocene.
Tertiary beds. Red Rock Pass 173
Tertiary lakes 98
Texas, interior basin 11
Thermos Springs, measurement of heights 408,415,417
Thompsou, Gilbert, contributions toEonnevillemap. 126
map of embankments near Dove Creek 138
discovery of outlet. 173
cited on Bear River drainage 219
map of mouths of Little and Dry Cottonwood
Canyons :!46
Thomson, AViUiam, cited on elasticity 381
coetticient of diffusion 42G
Tidal shores 28
Time ratios 159,260
Tintic Valley Bay 104
Tooele Valley, ancient shore-lines 14
Provo embankment series 131, 132
fault scarps 353
INDEX.
437
Page.
Tooele Valley, diaatropbism 367
(See alao Grantsville and Pass between Tooele and
Rash Valleys.
Tooele-Rusb Bay 104
Topograpliic features of lake shores, described 23
distribution 6
discriujinated 74
Titpnnirnpbic interpretation of lake oscillationa 262
Toronto Harbor, structure of peninsula 5-i
map 54
Towiia on site of Lake Bonucvillo lOG
Trans-Pecips interior basin 11
Transportation, littoral 37
Traverse Range, fault scarp 346
Trees uf Great Basin 9
Trrsca, flow of solids 383
Triaugulation, heights measured by 406
Trowbriujie, E, R., general assistant 18
Tuilla Valley. See Tooele Valley.
Tufa, near Pyramid Lake 33
of old shorelines 167
not found in Cache Valley 179
on Tabernacle lava bed 330
Tuff.Pavant Butio 326,329
TaberiLtrlo Butte 329
Twin Peaks, measurement of shore-line 408,415,417
Tyudall, John, cited 284
Uiakaret Mduutains Pleistocene eruptions 337
Uuconfoimityof White Marl on Yellow Clay. 190, 192, 194, 197
Undercutting 15L
Underscore 130,132
U:;clertow. origin 30
function 33, 38
pulsation 33
Uphaui, Warren, cited 272
Upper River Bed. section 194
geologic map 191
Utah Lake water, precipitation experiments. 206
analysis 207,254
Utah Valley, fault scarps 343
Valleys of Bonneville Basin 91
Valleys of Great Basin 6
Viisey, George, identification of fossil plant 210
V-b:ira, description 57
outlines 58
of Bonne villu shore-lino 108
interpretation 121
Vegetation of Great Basin , 9
Vertebrate faunas, compared 397
Vertebrate fossils and Bonneville climale ..'... 303
Volcanic district near Fillmore, map 320
Volcanic epoch nut clos-jd 339
Volcanic formation of Bonneville Basin 319
Walled lakes 71
Walling, H. F., theory of joint structure 213
Warm Spring Lake 300
Wasatch glaciers and Lake Bonneville 305,306
Wasatch Range, fault scarps 342
loading and displacement 357
now growing 359
volume 389
Water analy sea
Water of Great Salt Lake
Water of Lake Bonneville
Water of Sevier Lake
Wave-built terrace, described
compared with other terraces
Wave-cut terrace, described
compared with other terraces
Waves, shore-forming agents
theory of
refraction
function in littoral tiansixutation
fetch
function in building embankments
fetch, on Lake Ontario
Webster, Albert L., computation.
survey of Escalaute Bay
map of shore features at Wellsvillo
compilation of gauge data
map of Fillmore volcanic district
barometric work and compilation of altitudes. ..
appendix on altitudes
Weber River, deltas
change of drainage
fault scarps
Wells ville. view of terraces /. .
discrepant shoie records
embankments 137^
map and view of ombaukments
measurement of heights 372,
Wheeler, George M., position of Sevier Lake
Wheeler, H. A., survey of Tintic V;illey Bay
map of embankments near Grantsville
map of Snowplow
map of pass between Tooele and Rush Valleys. .
map of Fillmore volcanic district
Wheeler survey, investigation of Lake Bonneville..
map of Rush Lake
measurement of shoreline
White, C. A., explanation of lake ramparts
White Marl, character ami distribution
upper River Bed section
cause of whiteness
analyses
over lava
White Mountain, gypsum
map
rhyolite
height of Prove shore-line
measurement of heights 408,412,
White Valley and Stausbury shore-line
White Valley Bay
Whitney, J. D., observations on ancient shore-lines
of Mono Basin
cited on cause of cstenaion of Mono Lake
cited on climatic history of Great Basin
cited on synchronism of glaciatiun
cited on glaciatum and heat
cited on relations of Plei-stocene lakes and gla-
ciers '.
Owen's Valley earthquake
Whittlesey, Charles, cited on subaqueous ridges
Willard. heights of shoredines 365,
measurement of heights 412, 413,417,
Page.
207, 254
252
204
226
55
84
35
84
29
29
30
27
43, 107
46, -17
53
110
126. 370
138
232,409
320
365
405
164, 349
218
349
98
124
139,143
138
412,419
224
126
134
138
138
320
17
228
362, 414
71
190
195
200
201
328, 334
223
320
338
370
415, 418
186
104
16
266
266
270
284
314
3G2
43,44
370. 372
418,419
438
INDEX.
Willow Springs, hook near 145
\V iiiii waves, theory 29
Winds, Pleistoccno 332
Woir, fossil 303,394,400
Wocidwanl, R. S., on tho deformation of the gcoid
by tlie removal, tliroiigli evaporution, of the
water of Lake liouni-ville 377,421
on the elevation of the surface of tho r.onni-villn
Basin by expansion due t" change of rli mate. .'I7H, 425
Papo.
Wi.oilwanl, R. W.. analysis of tufa 168
Wright, O. Frederiek, cited 274
VVright, George M., field work 18
observation of oolitic sand 169
Yellow Clay, charatter and dialribntion 100
upper Jviver Bed section 194
analyses 2U1
Young, Williaid, riled 173
V
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