Full text of "Alaska"
SEM
=S==o
—<$—S
=—r
——6
==n
————— |
———lf)
S—
—————
a
—— bad
——_—*
=— (9
Digitized by the Internet Archive
in 2007 with funding from
Microsoft Corporation
http://www.archive.org/details/alaskaexpOSharruoft
ALASKA
VOLUME III
——
A EEE
*.
- i
a),
Lie Aa
aie Ni
SRO
i
}
i
Di
a
Ae Sia
; NEAT,
% } Fram wt
;
OS. sae i, ue
Ty Por #
A fm ei
Cierny ceils
ma Ca
Wisticer
Date Pos ‘
a Pie iy AA
ppd Sas
VOT
)
ye .
pet Alt
tg Ch eroe?
aay} ‘
ye 1
[a tatls
7 NY Pk ai |
ine oe
Me =
: be ;. i
4 "4 Ar
We cs
mye
ray
nee
nae
RAR
“at hm \
df
L'a j
*h
hay
sh + 1
a utes Re iris
peal nw
ot ru"
] Pas
Ld
ws
ed
FRONTISPIECE
H.A.E. VOL.|
John Andrew & Son.
Bryn MawrR GLACIER
="
SMITHSONIAN INSTITUTION
HARRIMAN ALASKA SERIES
VOLUME Iil
GLACIERS AND GLACIATION
BY
GROVE KARL GILBERT
CITY OF WASHINGTON
PUBLISHED BY THE SMITHSONIAN INSTITUTION
1910
ADVERTISEMENT.
The publication of the series of volumes on the
Harriman Alaska Expedition of 1899, heretofore pri-
vately printed, has been transferred to the Smithsonian —
Institution by Mrs. Edward H. Harriman, and the
work will hereafter be known as the Harriman Alaska
Series of the Smithsonian Institution.
The remainder of the edition of Volumes I to V,
and VIII to XIII, as also Volumes VI and VII in
preparation, together with any additional volumes that
may hereafter appear, will bear special Smithsonian
title pages.
SMITHSONIAN INSTITUTION,
WaAsHINGTON, D.C., Juty, 1910
HARRIMAN ALASKA EXPEDITION
WITH COOPERATION OF WASHINGTON ACADEMY OF SCIENCES
ALASKA
VOLUME III
GLACIERS AND GLACIATION
BY GROVE KARL GILBERT
NEW YORK
DOUBLEDAY, PAGE & COMPANY
1904
CopPpyYRIGHT, 1904,
BY
EpwWARD H. HARRIMAN,
PREFACE
THE present account of Alaska Glaciers, by G. K. Gil-
bert, forms the third of the Harriman Alaska Expedition
volumes and the first of the technical series. It is based
on observations made by the author in the summer of
1899, while a member of the Expedition, supplemented
by information and photographs from various sources, and
is illustrated by 106 text figures and 18 plates. The vol-
umes on Geology, Cryptogamic Botany, Insects and Crus-
taceans are to appear simultaneously with it. The vol-
umes on Nemerteans, Oligochetes, and several other
groups of Invertebrates, are ready for the press, and will
follow as soon as they can be printed. The two volumes
on Phanerogams, or flowering plants, are expected to ap-
pear early in the year 1904.
Acknowledgments are due the Canadian International
Boundary Commission, the United States Biological Sur-
vey, and, especially, the United States Geological Survey,
for the use of photographs and other illustrative material.
The editor wishes also to express his appreciation of the
drawings prepared for this volume by Mr. W. E. Spader
and Mrs. Louise M. Keeler. The frontispiece, plate x1,
and a large number of the text figures are by Mr. Spader,
while all of the chapter headings are by Mrs. Keeler.
C. Hart MERRIAM,
LFtditor.
WASHINGTON, D. C.,
May 1, 190}.
(v)
CONTENTS
PAGE.
MORTON spss ain coe ne cgoase ras pas seu ionssietes Ss cule tater tes esenkevens I
PWN Bag ei sis yous s cdus npces sks days gon cepeds¥endbavaneesvansteess 3
RUA TIUN ens fc catc cn eauo Aas ecu rahicdnaay ie sa nae beanie hea bweeh oes 4
COSA eR BE Revi GLACIERS 65: iocss js natasisjenavsiuserssenuenes i
SR ERE SL IPEREE NOD yas oedn sx skssnaaers chee sededtannwesdehe cases chess 7
RAR gus cap inncana gan toneuaveds nesses tan an eearogs desias candguepease II
CONSTR SOR coer soo eee aeons dbs cans ca sucneuwac ned cuxeincnvetans 16
DLE RR UMCMCR A iesic cs rcntenecastenso uss Pattpedes cone canseseevascuen suk 20
PACS TUK 5 adindacn ae pedsse vest pidewisienckaeds yanvenie bealeana tess 25
SOE ica Pas Sen laks Abd Soisednn$ chdsnWawnd ke seer esiutess snes eae tesses 33
RAVUIY. FRE, SIMON oon 6s oh l via pens dash eenicks sa snescrneiicee sess 34
RDRMERE AVON chasis va snuconearvinssedessusts yaar eeceutia conte 38
DM SMUG ARACIEE Sits dcsasvncesscosgue daneavaunciewentasy Sineesinenre 39
MAM TIO io sas cccen ssc paree tsa neisacnssnatencacceetiadeskasuovuress 45
BERMUDA: CSENCRED Ge socks ccs ap «son dn sundaes end usnceahotevsesinnse 52
PRIA ANCE yoa 5 cei co oe casas sk okie sea cuswasentnns 44 ccheseeds 58
REE OLE CRIN CION Fs ied oan as buy vp vacua we Soa Roose beets 63
Pe NIE EA MCIOR diss nay ceca ch Sasnces ev ceexwasevscssecovsieusonens ate 66
WWE PURI eit esG ky cl eh his iaies sans dcr eabariaasa ceee ti eeies 69
GSI: COMMONER: fo cer oc cecsyenutsanssaeetaarcnanerssahaavacueeee ss 71
RONCG TNE hin cae vedainsoidaanceisnine eas dese ee sabaaerreieeauiaaer: 81
PRGEINADS COT cs Se eee caw scr cacwag scp nonaecategecaneescenteence 89
CRE, CINCIOE oa ca cunis vcs ocenn ses goneeachecedocesecphertesets nee £07
PUMINIALY OF THOETE CORNICE 555 icscen crscsecscsess veces enseessy sess 102
GOES cg r4c5 sons dd av onsees tives setae tan casney LeeehadenRaacesseesen 106
CHAPTER II.—PLEISTOCENE GLACIATION .......csccscscscsosssccecees pe
BEAUGIO V BUCS. 6 linicc cs ddncscncseceasaa vores besseutivas eos panceens tes 114
MIRC OL TIAN VASGA IONS 65055 ston cecceg a caaneecdriacesecn ease 119
PPS-PICLOCENG TODORTAN IY oo ooo ts wen cs rus cue tcerecn eerenes 122
Ae: PRIS PONG AN cacia race sup tiscae stems snes oe des se 123
LAW POREDIANOS Sa cc cuas son eases cSadevaievelegnieswout cilese 130
Pu NG WEE DSASOAEVEN oasn osc cewesnients sinecamy es teceaeress 134
SOOTY oss ans cose pctuacn. asians parse iasesiaton tence 139
Vill CONTENTS
Cuaprer II.—PLEISTOCENE GLACIATION (continued). ica
District of Inland Passages (continued).
GlachatiOn | ...6c0.s0sosieecenessn<vanser suns edenaemeeerads ubeseeees 139
Rounding of angles............0..secsssersbuedetonsisezons ans 139
CirQuies ....scdasgsdias cae desapechinn ihe sa ves caeeaoepeemeag nous 141
Fiords and Hanging VatlleyS.......5.0.xescinanpecaeeaessae 142
Inequality of glacial erosion, ....:....:iedvadbeyseasesenes 159
Glacial dé posite... cs.cs<isacacdscacaussenesvaremeaygenststes 161
Associated sea-levels.. ...6s5:.ivs.sicnsotbeacesaionmedins 162
High Mountain district. ....5...ssi..ccessesstsespanbeeqenebay tnemrtens 166
Prince William Sound.........<s:<as0ss04¥eedeuh babeubinn cathees aye 173
Kenai Peninsula......0....000-00s.s00sdenevendnateahensmene ope Rienny ein 177
Kadiak Island. .......0.sssecccessesseccsuuy «caus oetnne din eernaenreniens 177
Region of the Gulf Coast....... issccesccavcsnavesbsdb apse tentenees 182
Unalaska Island..,........scsssescassvesteestensewadeutin che leeReeen 185
Bering Sea...... su divewd vvadddaweadey sei r0asanes ewe cat oahe een anne 186
CuapTER II].—GENERAL CONSIDERATIONS AS TO GLACIERS,.... 195
The surface of @ QIACiel. ....5csccsceevcineaessscangun Ghee semen 196
Evenness as compared to rock floor..........:ccsesseceseeseee 196
TLAtePAL Cll ys cos ocr ce cu evans haecdeccndatauh tanya beeanscaeenmeanem 197
Crevasse CY Cle sc. iicc cores doves var vonessshcanvaneenes ane 198
Glacial ect prune ci 5, ccckiva svensavsccanacecstetnrtsdotnescceuvapeen 203
Pressure and erosive power of Tidal Sica csaseeansuaaapaue 210
Rivers of ice and. Gf waters, 0. 025 .ues sve pesswransavenvanneeee 218
Resemp lances o.60. 5) is. acsiies Saasu se cecaqu seus tacaaus pave saeee 218
DOT ETENCEs tage aie anes nate ce rans aalsaassceuee ou tes av aaa e eee ete ee 220
FOO OT ANDY y
Lol
ILLUSTRATIONS
PLATES
PLATE PAGE
Sy <P See DE A HIACIOL sh asvavan cr cudtasedeccss asubsceudeots Frontispiece
i... Map of Alaska, showing route.......12..:..ccsssebssactacsucte I
RAE. BAUS PUGUCE ASIACIOR a sis soinvsewaavscrcendbvepabvapsordvesstaees 36
BM x, PARI | EEPROM NTTRONET «ins cvecsandsuvadsnsvsvisberv ence oeeuy 52
FE 5 PN ised ed San ang bien 5 capa diipecarainh inde easel concesiee 54
VI. Profile of Hidden Glacier. Section of moraine............ 56
Wil. Mag.ok Tanstak SIAGer, 00s ccespsicscennessecsvcssscnsvedeasave 58
VIII. Map of Hubbard and Turner glaciers...................00008 62
IX. Panoramas of Hubbard and Columbia glaciers............. 64.
x. Turner Glacier in 1591 ahd in 1890........sccssccsconescccces 66
Pak, BES OF Cotte GIA Chel, 6 i. nce se scnsreveseccnesssinvsseess 70
XII. Columbia Glacier, from Heather Island...................... 74
XIII. Maps of Prince William Sound and Port Wells............ 80
AIV. Amherst and Crescent giaciers..........cccsecsscscossecsesscces 82
POT RAEN OME Cis saint waonisdchaans s'seedeoeeiueninends'nédie> Kaien 94
AVI. A hanging valley, Fraser Reach.........ccccssesecessccssecese 116
XVII. Lowlands near Wrangell and Sitka...............ccecseeseeees 132
XVIII. Glaciated rocks.,...... Rian sabeeapnasnavensas ta skuadanns¢esyaesats 206
TEXT FIGURES
FIGURE PAGE
« Distribution of glaciers if Alasikn.. 0... .....ccccsccccccscscscccces 8
Davidson Glacier, from periinetala.s io. iisi.c.c.cccccccccssesesees 12
Davidson Glacier, froni above... .cccidicserccvcesccsses seesancants 13
SPEVIGSOR: GFIACIEL, SIDE VIOW 05 sciscesawssvorercarnessarsiccscevcseres 14
DOREY OF IIACUIGOR NEAT os sac asesnciens vovendeestantsesncisd Coeatene 15
Longitudinal section of Davidson Glacier...................0000e 15
Map of Glacier Bay........ anaes aus esuinaiee ha tes See onwanieg aeuarioues 18
Remnant glacier south of Hugh Miller Inlet..................... 20
DIELS RSRON Sha ch tuhs oc caus Spnseanauics cient ee aad evs anateseeeisass 20
pa ER UIE PEON ais ses pa cg be scagnseseccusancstesnsescetesctsanes 21
OED OE SEOEE SUNDEE Fn Cyc tigu ack svar Vecouess Ua ieksea yee evencenes 27
(ix)
x ILLUSTRATIONS
FIGURE PAGE
12. Reid Glacier, from the north.......0c0cac<oveccanaveeaesourabeswanen 28
13. Reid Glacier, from the northeast... 5..,ciisaccneshabeeasancwans 29
14. Reid Glacier, from the north Wert....04.; iccccureocptateeosseumiaben 30
15. Reid Glacier, from the northeast... ..iac.stecsncosn phavanastanaes 31
16. Rock-laden berg’... wcisscinsssosecvetneeiaeansunenceeeniaeninaahtevs 33
17. Map of Hugh Miller: Tite oe cnenscascugsnseounvasansauenednenaceve 34
18. Till left by Hugh Miller Glacter ss. ion icc ecseddeatonss rea hece 35
19. Charpentier GIActe? iosis.ssasaceenaidepseseyensandeeamigseeiatess 36
20. La Perouse Glacien, i... .ci.siccpetenacanshowasend demetweiliaaneniateecs 39
21. Map of margin of La Perouse Glacier..................ceseeeeees 40
22. Section of timbered ridge near La Perouse Glacier............ 4I
23. Barren zone at margin of La Perouse Glacier................... 41
24. Push-moraine of La Perouse Glacier..............ssssesscseeeees 42
25. La Perouse Glacier; contact with forest.............ssssecesesees 43
26. Map of Yakutat Bay -..5..0..+,.ssosciousssesvanneosignebsaranaoniaeeete 46
27. Map of Yakutat Bay, showing configuration of bottom...... 50
28. Hidden Glacier......csisersscccssscsetesesecesnseh)saaueniieeeiaameaee 53
a9. Waste plain of Hidden Glacier............c..sssesedsaskebananeneel 57
30. Westward from Nunatak Glacier... ....5..0s:0.jccseenyanvaaewns 59
31. Tidal front of Nunatak Glacier.....c...:,.s:ececsssaeecsnepennrien 60
32. Cascading glacier in Nunatak Fiord................scsscescoseeees 61
33. South tongue of Nunatak Glaciev.........:sscovdvnsensacseubeb nants 61
34. Tidal front of Nunatak Glacier .......55.cc0s cxcenentnsveodasanen 62
45. Hubbard GIacler. ...05.5.0.0scs0ssnesendsecsecess taney veces Gieueoerd aioe 64
36. Longitudinal section of Turner Glacier................ceceeeeeees 68
37. Panorama of Columbia Glacier.. ..........csussvensveadevee tan ves 72
38. Western edge of Columbia Glacier... ..,.....cisevasstnvrenoe ten 76
39. Push-moraine, west shore of Columbia Bay...............see00 77
40. Fluted moraine at edge of Columbia Glacier..............e0006. Y
41. Moraine marking attack by Columbia Glacier on forest...... 79
42. Outlines of Columbia Bay: .....:ccccicsenesiesocasnpes sohommonns 81
43,. East: past of front of Yale Glacier... ....assesscakessnccersmeatiots 83
AAs, Tlarvard GIAcier iiiss.sccdacecvexonsrweccsahasppaceumunkseenesaseesir es 85
AS.. West side of College Pion i.5.< 2 Guvienave biaceonstencuasnac senate 87
46.; Distant view of Batey Glater. 2.05 clcrecsicany we tsnce i nieenreee go
Av. PartOr Front. Of TRArey CHAR cals sec nce car ccnencercasivess ov ies gI
40. Caves in frontal cli of Batey (slactet 560. cciscvendciectanseees gI
AO; kuast part of front Of Barty S51AClers.ic.25 2.00 rssseeseceencouscpes 92
HOe eTPEMEING CIACIEN 15015 ceten ves assiwasaseasesscaroassaseeadncites ee: 93
S¥s OUurprise and Cataract CiAClete, 665665052 io eansce paasiecnsesades sass 94
ILLUSTRATIONS xi
FIGURE PAGE
52. Hemlocks bordering Harriman Fiord ..............csesseeeeeeeees 97
CBs RAMU SPARC cea rsaxcinverishaceéunss ons onapadtodentdpetgieseont 99
54. South wall of valley at front of Grewingk Glacier............. 100
eo . Lreneeipation OF placier IGCAMGICS ........cicesvsasedornsenscddatean ass 105
56. Diagram illustrating origin of hanging valleys.................. 115
57. Diagram illustrating origin of hanging valleys................4 115
58. Diagram illustrating discordance of hanging valleys........... 116
59. Map; fiords of the Inland Passage district....................645 120
Bee RO Ue RMON COIs ia o5 oss ciceca union ces esds ehewuk us San'vanshepcudececebeeans I2I
61. Upland topography near Cape Spencer,.............ecseeseeesees 125
62. Upland topography near Berner Bay...............sseccsecesesees 127
63. Upland topography near Walker Bay ..............ccsececeeeeeeee 128
ik ANAL CE VOTRE SOLAN, oi das cbs pe tir nescnaiin nae tapecnvedsncenndabens 131
He. Cid penepiain nest BUA s5. 5s cas win loads skencevernsdinevencatines sce 132
hs. Dougias Teland, Fem FuAeAte boi. aces cocdsssabactnesecssatnces seuss 133
fi. A. fiord of the: Inside, Paap... sesocvedesssssescseeeepacesvarsanss I4I
Gs) A ford of the Insiibe Passage «........sccscccsasecsevvcvescenseveces 142
69. Hanging valley on Vancouver Island................cccceeeeeeeees 143
70. Hanging valley on Princess Royal Island.....................065 145
Us, sannorne valley, P¥aser Kah, ,...0sccssnescscsecectsececcsvccsnses 146
a, SAamne Walley, F'PAbet FLOR. 5.550eciiswexesecesccscsonsseaeness 146
Sr ROC WEIL GE LAE: TOWN nas cs neces sovenstsewsesccssocesecenetenssns 148
na WO Oe OR SAT TO 56 as 5.05 Ra csnsas ds hesaode ss siassvevescainse 149
TERME AG RMON SMININ S555 50.90, hxs sislsdsddadsboeseedenedepssancersvesias “152
i SUMED GUAGE, “ESIGA ENC s. cccsocncs coc cvossstessscnesesacscrenes 153
oy, ortheast wall of Chilkoot trough..........csscsecsseresosssveosee 154
a: Profile from ‘Taiya Pass south wat ....0.0..cscsccsecsersensecsocss 155
479. Cross-profiles about head of Lynn Canal.................ceseeeee 155
dn PROMS GR: SOO IVER: os crasrecacsavednaeadanesise sack ledvens séaueee 158
Sis SIRS VERO, INMNRAR BION so) ox cin cas saviesvncscsseanscssccnns IVI
Dba dN TURE SOA i ies sc ccoaypasandtekeutasincsnpsebeseuacdnaee 174
53; Hinchinbrook Island, from the seac....0i0ds.scsesecsserrssecesens 174
84. Diagram of northwest wall of College Fiord.................... 175
85. Terrace on Spruce Island, opposite Kadiak Island............ 179
SMa DEAMEUG GRE Se PATEM ES Sy ju race Yok gentssRernseunmeaancsenamernenkiGa tetas 180
eta, WADIE ROCRIN Ma MIR VIA IE So sii ceacessed eeae ns Videwsensste'arenns 181
88. Hanging valley near Kadiak village,.........ccecsoovscsscscsessee 181
ma. Acrater s90r oi St. Pant Islas ooo. ss sa coca eseneties tosdngeaice 187
90. Unglaciated knob on St. Matthew Island.....................008 189
gi. Stream-graded valley near Port Clarence ...............sceeeeeee 189
Xil ILLUSTRATIONS
FIGURE PAGE
92. East wall of Plover Bay, Siberia.....<..csccovsdanedhan soeadeenanns 190
93. Hanging valley, Plover Bay......0:1s0ssseesspacacupveessewannepangel Ig!
94. Downward limit of crevasses in Muir Glacier.................. 198
95. Crevasses and seracs, Muir Glacier... .c<ccusicigssiisenaenecbene 199
96. Pinnacles on Columbia Glacier.............csesesseseeeeceeceneees 200
97. Back of Columbia Glacier..............sssssesereecnserecsecsseeeres 200
98. Level tract on Muir Glacief..ic.cccciesssacaseisneeayars onagateaiess 201
99. Ideal profile and section of a glacier... 5545 Acssseiiervnenedes 201
100. Ideal section of water-filled crevasses...........ccceeseeeeneceeeees 202
101. Influence of drift on surface character of glacier............... 202
102. Ice sculpture in Russell Fiord,. . i.) .xicdecpasngeds ies eaves 209
103. Diagrams illustrating flotation theory of tidal glaciers........ . 210
104. Diagrams illustrating non-flotation theory of tidal glaciers... 211
105. Contact phenomena of glass and mercury............sceseseseees 212
106. Ideal section of tidal glaciet...............:isseskseeage banana 215
=e ea eel —> m2,
Ss ae
OrKaN-rO
weenie
NE
GLACIERS AND GLACIATION
BY GROVE KARL GILBERT
INTRODUCTION
THE glaciers of Alaska are many and the district
through which they are distributed is large. The region
formerly overrun by them is still larger. Ten years
ago Russell and Kerr surveyed and studied Malaspina
Glacier and its dependencies, and about the same time
Reid made a scientific survey of Glacier Bay and its
bordering glaciers; but these two tracts are only dots on
the general map. All other glacial studies in the great
field have been of the nature of reconnaissance and most
of them have been carried on incidentally in connection
with general geographic or geologic work. The Harriman
Expedition added one more to the list of reconnaissances.
Until recently observations have been limited to the
coast and it is still true that the greater number of glaciers
which have been studied or mapped are coastal, or at least
visible from the sea; but at the present time interior gla-
ciers are receiving more attention, and knowledge of them
is rapidly growing. Geographic investigation, so long as
(1)
2 ALASKA GLACIERS
stimulated by only the fur and salmon industries, was di-
rected chiefly to coastal regions, but the development of
gold placers turned attention to the interior, and for sev-
eral years the topographers and geologists of the United
States Geological Survey have been actively engaged in
the exploration and survey of inland districts.
The growth of knowledge of Alaska glaciers is so rapid
that a summary of existing knowledge would have but
transient value. Generalization as to most points of world-
wide interest is at present impracticable because observers
have differed widely in their preconceptions and criteria,
and the data consequently are not homogeneous. It has
seemed best, therefore, to make the present report pri-
marily a record of the data gathered by the Harriman Ex-
pedition and to make use of other material only when it is
closely connected with the new data or is otherwise ser-
viceable in their interpretation.
Regarded as a reconnaissance of glacial geology, the
cruise of the ‘ Elder’ was fairly comprehensive. It not only
covered rapidly a wide extent of coast but it brought
under view a great variety of phenomena. The general
impressions acquired while the ship was skirting the coast
were supplemented by the results of more definite and
detailed observation at a few points on the land; and the
impressions,acquired by local studies of individual glaciers
were enlarged by the panoramic view of many others.
Opportunities for close examination included landings
from the ship at thirty-four localities, at three of which
the use of a camping outfit extended the time to several
days. ‘The remainder of the two months covered by the
voyage was spent on the ship, and about half the sailing
time was so conditioned by distance from shore, by light,
and by weather, as to permit profitable observation of the
coast. After the voyage was over physiographic studies
were continued by the aid of photographs. Thousands of
INTRODUCTION 3
views by members of the Expedition were examined, as
well as a large number from other sources, and at least
several hundred of these have yielded information as to
glaciers and glaciation.
In arranging the material for presentation it has been
found convenient to make an arbitrary division of the
history of glaciation, connecting such changes as appear
to have occurred within a few hundred years with the ex-
isting status, and classing all remoter changes with the
geologic or Pleistocene series. This procedure is a matter
of convenience only; it is not determined by a turning
point in glacial history, but by a difference in the nature
of the evidence by which the history is recorded. The
direct observational record, for a few localities, reaches
back a little more than a century, and inference from the
age of trees extends a little farther; but for all earlier
times the data are purely geologic and the changes have
not been measured in years.
Under this classification the heads of my principal chap-
ters are Existing Glaciers and Pleistocene Glaciation.
The changing relations of sea and land also receive atten-
tion, but these are so closely connected with the problems
of Pleistocene glaciation that they have not been given a
separate place. Notes of a general character as to glaciers
and their work are in part introduced along with local
descriptions and in part assembled in a closing chapter.
Route.— Through the greater part of the journey I re-
mained with the main party, so that the red line on the
route map (pl. 1) shows my course with approximate
accuracy. It seems necessary to mention here only a few
deviations and details. Such dates as are of importance
are noted in connection with the descriptions of individual
glaciers.
In Glacier Bay I spent a day and a half at Muir Gla-
cier, and then, with Muir and Palache, visited Hugh Miller,
4 ALASKA GLACIERS
Reid and Geikie inlets in a rowboat. This excursion oc-
cupied four days, three camps being made on the shores
of the bay.
In Yakutat Bay I landed at Hidden and Nunatak gla-
ciers and at the summer village of the Yakutat Indians.
Two days were spent, with Muir, Gannett, and Kearney,
in a boat excursion which visited Hubbard Glacier and
Osier and Haenke islands.
In Prince William Sound I touched at Orca, and was
then left at Columbia Glacier with a boat and shore party,
including Palache, Coville, and Curtis, while the ship ex-
plored Port Wells. We remained three days, and after-
ward had a partial view of Harriman Fiord.
In Cook Inlet I was landed for a half day at Grewingk
Glacier, while the ship made an excursion up the main
bay.
I was with the ship on all routes about Kadiak Island,
landed briefly on the western coast, spent several days at
and near Kadiak village, and visited Long Island.
At Port Clarence I was of a party that crossed the bay
in a launch and visited the mainland.
Photographs.— For the study of changes in the size
of glaciers photographic views are of peculiar value. A
view showing a glacier or part of a glacier in relation to
details of adjacent land constitutes a record which can at
any time be compared either with the objects themselves
or with another photograph made in another year or
month. That a photograph may have its highest value
for such use its date must be known, including year,
month, and day of month. The Harriman Expedition
carried many cameras and secured a large number of
views of glaciers. Some of these views are reproduced
in the present and preceding volumes, and are thus made
available for the investigator. So far as they are contained
in this volume, their dates are given in the associated text.
PHOTOGRAPHS 5
The geographer who shall undertake in the future to study
the variation of Alaska glaciers will have use not only for
the fuller details of the original photographs but for a
more complete series, and the following information is
given for his benefit.
Of the many series of photographs made by the mem-
bers of the Expedition, three may be regarded as public,
and these also contain the most important records of the
glaciers. Mr. E. S. Curtis, the official photographer of
the Expedition, made the largest and best views, and keeps
them on sale at his photographic establishment in Seattle,
Washington. The negatives made by Dr. C. Hart Mer-
riam are filed at the office of the Biological Survey, U. S.
Department of Agriculture, Washington, D.C. My own
negatives are filed at the office of the U. S. Geological
Survey, Washington, D. C., where a set of prints may be
seen and prints from negatives may be ordered.
The dates of our photographs for the several glaciers
are as follows, the year 1899 being understood in each
case: Amherst, June 26; Barry, June 26-29; Bryn Mawr,
June 26; Cataract, June 27; Charpentier, June 11; Colum-
bia, June 25-28; Crescent, June 26; Crillon, July 24;
Davidson, June 6; Grand Pacific, June 12; Grewingk,
July 21; Harriman, June 27; Harvard, June 26; Hidden,
June 20; Hubbard, June 19-22; Hugh Miller, June 11;
Johns Hopkins, June 12; La Perouse (near views), June
18; La Perouse (distant views), June 18 and July 24;
Muir, June 8-13; Nunatak, June 20; Radcliffe, June 26;
Reid, June 12; Roaring, June 27; Serpentine, June 26-27;
Smith, June 26; Surprise, June 27; Turner, June 19-22;
Vassar, June 26; Wellesley, June 26; Yale, June 26.
The table on page 6, giving series and negative num-
bers of photographs from which text figures were made,
includes most of the figures based on photographic views.
Information as to others is given in their labels and other
6 ALASKA GLACIERS
associated text. ‘Titles of series are abbreviated in the
table as follows: ESC=E. S. Curtis, Seattle, Wash.;
USGS = U. S. Geological Survey, Gilbert; USBS =U.
S. Biological Survey, Merriam, 1899; CBC = Canadian
Boundary Commission, Ottawa, Canada. The Boundary
Commission photographs are mounted in an album of
many volumes, and the complete reference includes num-
ber, volume and page. <A copy of this album is in the
library of the State Department at Washington.
SOURCES OF PHOTOGRAPHIC MATERIAL USED IN
TEXT FIGURES.
Figure. Series. Negative or Photo. Figure. Series. Negative or Photo.
2 CBC 3, ¥. 32,9: 5 54 USGS 456
3 CBC 117, V. 12, p. 43 61 CBC | 93-4, Vv. 14, p. 53
USGS 247 62 CBC 96, v. II, p. 30
§ USGS 282 63 CBC | 132-3, v. 8A, p. 50
9 USGS 270 64. USGS 222
12 CBC » Ve 14, Pp. 13 65 USGS 324
13 CBC 38, V. 14, p. 11 66 USGS 470-471
14 USGS 259-261 67 USBS 293
15 USGS 257-258 68 USBS 55
16 USGS 276 70 USBS 250
18 USGS 281 71 USBS 292
19 USGS 263 72 USBS 251
20 USGS 467 73 USGS 221
23 USGS 334 74 CBC | 109A, Vv. 12, p. 81
2 USGS 333 75 CBC 93-4; V- 12, p. 3
2 USGS | = 365-366 76 USBS
29 USGS 367 77 CBC 68, v. 12, p. 42
30 ESC 259A 80 CBC 93, V- 6, p. 43
31 USGS 305 81 USGS 373
32 USGS 302 82 USBS 94
33 USGS 307 83 USGS 383
34 ESC 259 85 USGS go
35 USGS 298-299 86 USGS er 400
38 USGS 355 87 USGS 392
39 USGS 356 88 USGS 402
40 USGS 352 go ESC 393 (?)
41 ESC 311 gI USGS 433
43 ESC 275 g2 USGS 430
45 USBS 117 93 USGS 443
46 USBS 137 96 USGS 346
49 ESC 280 97 ESC 304.
50 USBS I51 102 CBC 3, V- 17, p. 3.
53 USGS 454-455
My
S<Z
ary
ey.
md
eZ
o~
XX ar)
L™ Ray
é
Si
XEN ;
Oe
a
UR
CHAPTER I
EXISTING GLACIERS
GENERAL DISTRIBUTION
NEaRLy all the glaciers of Alaska are comprised within
a belt of moderate width which follows the southern coast
from the Aleutian Islands to Portland Canal (see fig. 1).
Curving about the great bight of the Pacific Ocean known
as the Gulf of Alaska, this belt has a length of 1,600 miles,
and its extreme width, near the middle, is about 250 miles.
Within it the arrangement of glaciers is irregular, but their
more important groups occupy the middle region, while
near the ends they are comparatively sparse and small.
The explanation of this massing of glaciers along the
southern coast is not far to seek. The general circulation
of the Pacific Ocean brings to the Gulf of Alaska a cur-
rent of water which has been warmed in the tropics and
still retains so much heat that its mean temperature is
considerably above the normal for the latitude. The
ocean is therefore, at most seasons, warmer than the con-
tiguous land, and though air currents passing from ocean
to land convey heat to the land they are themselves cooled.
(7)
8 ALASKA GLACIERS
While traversing the ocean the air becomes loaded with
moisture, the cooling over the land diminishes its water-
carrying capacity, and part of its load falls to the ground as
rainor snow. Moreover, all this coast is mountainous, so
that landward flowing air is compelled to rise, and its capac-
ity is still further reduced by rarefaction. At the greater
altitudes the ratio of snow to rain is comparatively large,
" 158° 154" 150° 146° 142” 128° 134°
- =
\\\
166" 1g2 158° 154° 150 146 yee "18 134 130
FIG. I. DISTRIBUTION OF GLACIERS IN ALASKA.
The belt containing glaciers is shaded by parallel lines.
and the mountains thus become gathering grounds for the
snows that feed glaciers. Farther inland the air currents
descend somewhat and the precipitation is diminished until
the conditions for glacier formation cease. Hayes states
that while the névé line of glaciers on the southward face
of the St. Elias Alps lies at about 2,000 feet above sea-
level, its altitude on the northern face is over 6,000 feet.’
1An Expedition through the Yukon district. By Charles Willard Hayes.
Nat. Geog. Mag., vol. Iv, p. 153, 1892.
DISTRIBUTION OF GLACIERS 9
Along the western coast of Alaska the conditions are
different. Bering Sea lies practically outside the influence
of the Pacific circulation and the temperature of its water
is approximately normal. Its power to charge air cur-
rents with moisture is small, especially in winter; and
though the winter temperature over the adjacent land is
low, the snowfall is not heavy. There are no great moun-
tain ranges to concentrate the precipitation, and the snow
of winter, being broadly spread over plains or caught by
ranges of moderate height, is dissipated by the melting
and evaporation of summer.
The glacier-bearing belt includes about three-tenths
of the vast territory of Alaska. Its exploration has but
begun, yet enough is known to give it rank as the third
great glacier district of the world, only the Antarctic con-
tinent and Greenland surpassing it. Its ice may be
roughly estimated to occupy a tenth of the surface, or an
absolute area of between 15,000 and 20,000 square miles,
and this expanse is so divided and scattered as to offer to
the student the utmost variety of local condition and de-
tail. Of alpine glaciers, such as would receive individual
names if near the homes of men, there are many hundreds,
possibly more than a thousand; of broad, composite fields,
like the Muir and Malaspina, there are about a half dozen;
and more than thirty are known to reach the coast and
cast bergs into the sea.
Skirting the land in a ship and making only brief ex-
cursions away from it, we saw only glaciers of the coastal
mountains and lowlands, and close inspection was limited
to the lower ends of ice streams. The phenomena which
arrested our attention were those of wasting, of the depo-
sition of detritus, and of the advance and retreat of the ice
fronts. It soon became evident that our chief opportunity
to advance glacial science was through contributions to
the history of local changes in the frontal boundaries of
Io ALASKA GLACIERS
glaciers. That which was accessible to us had been
accessible to our predecessors also, so that at several
points we could compare present with past condition ;
and, for like reason, whatever record we might make
could readily be used by the investigators of the future.
Effort was accordingly made to visit as many as possible
of the glaciers already described and mapped, and at all
points visited to secure an intelligible record of the exist-
ing status.
The plural pronoun in the preceding paragraph is
not the conventional affectation of modesty, but springs
naturally from the consciousness that the facts I am
to present were not wholly of my own observation. In
grouping the material for publication it seemed to my
colleagues in geology, Emerson and Palache, as well |
as to myself, that it would be better to classify by sub-
jects than by observers, and as glaciers fell to my
share, I have absorbed the glacial observations made
by these gentlemen. I am greatly indebted also to the
map work of Gannett, to the historical data and fertile
suggestions of Muir, and to the timely cooperation of
Dall and Coville.
Before taking up the description of the glaciers, a few
words will be devoted to the terminology connected with
their broader classification. The distinction between a/-
pine glaciers (sometimes called glaciers proper) and con-
tinental glaciers (also called ice-sheets) has long been
recognized. Alpine glaciers are fed by névés in high
mountains and as rivers of ice descend mountain valleys.
Continental glaciers gather on broad plains or plateaus
and spread outward. Russell, as a result of studies in
Alaska, recognized a third type, the Azedmont.’ A pied-
mont glacier is a broad sheet of ice resting on a lowland
1An Expedition to Mount St. Elias, Alaska. By Israel C. Russell. Nat.
Geog. Mag., vol. 111, p. 121, 1891.
LYNN CANAL II
at the foot of a mountain range, resembling a continental
glacier in its mode of wasting, but distinguished by the
fact that it is fed by the alpine glaciers of the mountain.
An alpine glacier may be simple and separate, or com-
pound. Two or more often descend from the same névé.
Still more frequently two meet and coalesce after the
manner of rivers, and a trunk glacier may have many
tributaries. Small alpine glaciers are sometimes called
glacterets, or, if visible high on the sides of mountain
valleys, hanging’ glaciers.
For the purpose of the present report it is convenient to
distinguish glaciers which reach the sea and discharge
bergs, from those which end on the land. Reid calls
these, severally, ¢zde-water and alpine glaciers; and
they have also been called (after whose initiative I do not
know) /¢ve and dead glaciers. Reid’s use of ‘ alpine’ con-
flicts with the well-established use already mentioned, and
the terms ‘ live’ and ‘ dead’ are clearly misleading, as the
great majority of the active glaciers of the world fail to
reach the sea. I shall abbreviate ‘ tide-water’ to ¢zdal and
employ zon-tidal as its antithesis.
LYNN CANAL
The order in which the glaciers were observed was from
east to west, and it has been found convenient to adopt
this as the order of description also.
On the islands of southeastern Alaska there are no
glaciers, and those of the mainland, south of Juneau, nestle
in recesses of the mountains so far from the steamer route
that we had only distant glimpses. But in Lynn Canal we
followed a great fiord between ranges at once so lofty as
to project well above the snow-line and so bold as to ex-
1Glacier Bay and its Glaciers. By Harry Fielding Reid. Sixteenth Ann. Rept.
U.S. Geol. Survey, part 1, 1896. See pp. 429 and 442. The term tide-water
was used by Russell as early as 1892. See Am. Geol., vol. rx, p. 322, 1892.
12 ALASKA GLACIERS
hibit their crowning banks of snow and ice in continuous
panorama. These ranges have been mapped in some de-
tail by the U. S. Coast Survey and the Canadian Inter-
national Boundary Commission, and it appears from a
comparison of the glaciers with contours of altitude that
the snow-line descends in both directions away from the
fiord. On the mountain slopes overlooking the water
glaciers do not form at a lower height than 4,500 feet, but
UK
ee
* ghd
\\
\\
=
~
iM
ya RUINS,
\\\ \\\
oe i
AY \\y*4
FIG. 2. DAVIDSON GLACIER, FRONT VIEW, 1894.
Showing the trench form of its valley, the spreading of its end, and the two zones of the
fringing plain. Photograph by W. Ogilvie, from peninsula at left in fig. 3. See page 6.
on the opposite slopes of the same ranges 3,500 feet seems
to be enough.
Davidson Glacier, fed by a high snow-field lying several
miles back of the first mountain crest on the west, flows
to the fiord through a narrow trench and reaches sea-
level, though its ice does not actually touch the water of
the ocean. In its mountain trench it has a width of only
a half mile, but on escaping from the confining rock walls
and entering the fiord it immediately spreads into a semi-
circular fan with a radius (in 1894) of about three-fourths
of a mile. All about its frontal margin is a fringe of low-
land averaging three-fourths of a mile in breadth, consti-
tuted, at the surface, of rock waste brought by the glacier.
DAVIDSON GLACIER 13
There may be much unmelted ice beneath the visible
gravel, but the lowland certainly contains a great body of
gravel which, if glacier and ocean were withdrawn, would
appear as a great curved ridge of water-laid moraine stuff.
Glacier and moraine together encroach nearly two miles
on the water of the fiord— a branch of Lynn Canal called
Chilkat Inlet — reducing its width to about one mile.
—
FIG. 3. DAVIDSON GLACIER,
View of terminal fan from the high peak at the right in fig. 2. Shows the barren and
forested zones of the fringing plain. The glacier is partly concealed by a rock of the fore-
ground. From a photograph by J. J. McArthur, 1894. See page 6.
The depth of the moraine, or moraine-delta, where it
occupies the middle of the fiord is more than 500 feet.
The profile of the ice fan, as shown by photographs, has
a slope of one foot in ten (see fig. 4). The gravel low-
land is much flatter, but the submerged face of the deposit
descends to the bottom of the fiord with a general rate of
one foot in three.
We made no landing here, and our facts are derived
chiefly from Russell, who visited the foot of the glacier in
1889; from the Coast Survey chart, based on surveys in
1890-94; and from photographs made by the Canadian
14 ALASKA GLACIERS
Boundary Commission in 1894.1 They are of interest in
this connection chiefly from their bearing on the interpre-
tation of morainic ridges observed farther west, at the front
oe ww we we ee eee rioae ac te a tt WR ne ais PN eee eee -_- —-
FIG. 4- DAVIDSON GLACIER,
Side view of expanded end, June, 1899.
of the Fairweather Range. If Davidson Glacier were to
melt away and the sea to retreat from Chilkat Inlet, there
would remain in the valley a high ridge of water-laid
gravel, recording by its circling course the present out-
line of the glacier front, and by its even crest line the
present position of the sea surface.
As to modern changes in the extent of this glacier there
is little specific information, but the condition of the fring-
ing plain warrants a few general statements. An outer
zone is covered by forest, an inner is barren (figs. 2, 3 and
5). The forest is in general lofty, dense, and apparently
mature, but a narrow belt next the barren zone has smaller
trees in rather open growth. The forest zone has an
average width of less than half a mile, ranging from one-
fourth at the north to five-eighths at the south; the bar-
1See page 6 and figs. 2 and 3.
DAVIDSON GLACIER 15
ren zone in 1894 ranged from one-fourth mile (east side)
to nearly one-half mile (north side). There were many
lakelets in the barren zone (1894) and a few in the forest,
SOME OT UES
FIG. §. MAP OF LOWER PART OF DAVIDSON GLACIER.
Based on Coast Survey chart 8303 and Boundary Commission photographs made in 1894.
The contour interval on land is 500 feet ; under water, 250 feet. Barren lowlands dotted; for-
est indicated by stars.
and these are probably indicative of the melting of ice
buried under the gravel. It seems safe to infer (1) that
for centuries (age of the mature forest) the glacier has
not exceeded its present extent by more than three-
eighths of a mile, and (2) that the period since it last
ae
yy yy eee F ee,
iMILE
SLA LEVEL
FIG. 6, LONGITUDINAL SECTION OF DAVIDSON GLACIER AND CROSS SECTION
OF CHILKAT INLET.
£, glacier. m, moraine-delta. w, water of inlet. %, profile of mountain range near glacier.
16 : ALASKA GLACIERS
reached the three-eighth-mile limit is roughly measured
by the age of a half-grown forest.
GLACIER BAY
The next depression west of Lynn Canal is broader,
as well as more complex in the details of its config-
uration, and its general trend is northwestward in-
stead of northward. On the west it is separated from
the Gulf of Alaska by the Fairweather Range, the
dominant mountain mass of this region. Glacier Bay,
occupying its main axis, sends many branches into
the troughs among “its hills and mountains, and would
be still more complicated in outline but for the clog-
ging of the valleys by glaciers. Six of its inlets head
against ice walls, from which bergs are constantly
falling.
The glaciers of this basin are better known to the phys-
ical geographer than any others of the Alaska belt, and
one of their number, the Muir, enjoys the same preemi-
nence in popular acquaintance and appreciation. The
group was explored, sketched, and studied by Muir in
1879 and 1880. Wright made.a visit in 1886, producing
a rough map and working out the main elements of the
later glacial history. Reid, in 1890 and 1892, executed
a careful survey of the shores, the lower portions of the
tidal glaciers, and a broad inland tract including the
greater part of Muir Glacier; developed much further
the history of recent changes; and instituted a number
of investigations bearing on the physics of glaciers.
Minor studies were made by Cushing (1890) and Rus-
sell (1890), the map work has been extended by the
Canadian Boundary Commission, and a fine series of
photographs were made by the Commission in the sum-
mer of 1894.
GLACIER BAY 17
To the body of information gathered and published by
these investigators* our addition was comparatively unim-
portant. The five long days of our stay, though utilized
to the utmost and replete with interest, served only fora
partial review of the features of the immediate coast. As
to the more general aspects of the topography and physical
history we verified the work of our predecessors, but we
were able to extend it only by bringing down to date the
records of changing glacier fronts.
Except near the mouth, the shores of Glacier Bay are
treeless, and large tracts are almost destitute of vegetation.
A variety of other facts show that this barrenness is due
to the recent occupation of the surface by ice, and the ex-
tent of the barren zone measures the amount of modern
recession of the glaciers. Another series of phenomena,
including vestiges of a forest and remnants of a moraine-
delta, show that the epoch of expanded glaciers was pre-
ceded by an epoch of contracted glaciers when the ice
occupied less space than at present. Thus, from a condi-
tion of minimum extent, the glaciers grew to a maximum
of brief duration and then wasted away to their present
dimensions. Vancouver’s narrative seems to show that at
the time of his visit to the coast (1794) the ice was near
its maximum, and subsequent observations, beginning with
those of Muir in 1879, show rapid and nearly continuous
retreat. The magnitude of this oscillation is perhaps
without parallel in the records of glacial changes within
the historic period. During the maximum epoch an ice
flood not only filled Glacier Bay for thirty-five or forty
miles, but submerged many islands and bordering hills
1John Muir, Cruise of the Corwin in the Arctic Ocean, p. 136, 1884; The
Mountains of California, pp. 23-24, 1894. H.F. Reid, Nat. Geog. Mag., vol.
Iv, 1892; Sixteenth Ann. Rept. U. S. Geol. Survey, part 1, 1896. H.P. Cushing,
Am. Geol., October, 1891. G. F. Wright, Am. Jour. Sci., Jan., 1887; The Ice
Age in North America; Man and the Glacial Period. I. C. Russell, Am. Geol.,
March, 1892.
18 ALASKA GLACIERS
from 1,000 to 2,000 feet in height and reduced the lesser
mountains of the basin to the condition of projecting peaks,
or nunataks. The sea front made a continuous ice cliff
ten miles long. Then the great trunk glacier gradually
wasted; therounded
crests of submerged
hills began to reap-
pear as nunataks;
rows of nunataks
coalesced into
mountain ranges;
the ice cliff retreated
up the bay, passing
one nunatak after
another and leaving
it as an island or a
promontory; one by
one the tributary ice
streams were aban-
doned by the waning
trunk and left as in-
dependent glaciers,
whose terminal ice
FIG. 7. MAP OF GLACIER BAY. cliffs retreated erad-
Ruled areas, land. SG, Brady Glacier. CG, Char- °
pentier Glacier. GJ, Geikie Inlet. GP, Grand Pacific ually up their several
Glacier. H/, Hugh Miller Inlet. HM, Hugh Miller sea arms. These
Glacier. H, Johns Hopkins Glacier. MJ, Muir Inlet. : L
MG, Muir Glacier. Q, Queen Inlet. R, Rendu Inlet. modifications of the
RI, Reid Inlet. W, Willoughby Island.
coastal geography
were accompanied by equally remarkable changes at
higher levels. Several glaciers lost their névés, by dis-
sipation or by diversion, and being thus deprived of
nourishment and of part of their propelling force, lie
nearly stagnant and are slowly melting away. A num-
ber of fragments of ice streams are stranded on flat
passes among the hills, where they lie almost inert but
SSS
Sw
=
re
<
TS
Seer Ss ss
mS:
Sace ~
'
vr
os fi
gz
SG
ear
%
ts
\)
GLACIER BAY 19
with slow movement on two sides in opposite directions,
part of the mass tending backward toward its original
source.
Of the abundant evidence from which this history was
worked out by my: predecessors* I saw only a small frac-
tion, but enough to substantiate their conclusions in all
essential respects. I skirted the barren coasts over which
vegetation is slowly creeping from the south. I saw
glacial till and gravel charged with bruised trunks and
boughs from the ancient forest. I saw the bare ice-carved
hills, still retaining striz and polish under a climate that
has obliterated from most exposed surfaces the similar
records of Pleistocene glaciation (pl. xvi). I saw the
banks of stratified gravel before Muir Glacier — remnants
of the old moraine-delta— and noted that their upper
surface had been first sculptured by the readvancing
glacier and then sheeted with till during the subsequent
retreat. And I saw a remnant of the ice flood stranded
on a saddle a thousand feet above tide.
The saddle to which I refer is part of a small trough
extending southeast from Hugh Miller Inlet and lying
parallel to the adjacent great trough of Glacier Bay.
During the recent ice maximum an ice current followed
this trough from northwest to southeast, and when the
supply from the northwest finally ceased and this strand
of ice had nothing to urge it except its own weight, its
ends slid into neighboring valleys, but the central part lay
balanced on the summit and became stagnant (fig. 8).
The adjacent hills are too low to furnish the snow needed
to replenish its annual loss by melting, and so it is slowly
wasting away
1Wright, Am. Jour. Sci., 3d series, vol. xxxu1, pp. 11-18, 1887; Ice Age,
pp- 55-62, 1889. Reid, Bull. Geol. Soc. Am., vol. 4, pp. 32-41, 1893; Sixteenth
Ann. Rept. U. S. Geol. Survey, Part 1, pp. 434-442, 1896. Cushing, Am. Geol.,
vol, VIII, pp. 214-224, 1891.
20 ALASKA GLACIERS
Of the existing glaciers of the basin ten are now tidal.
We visited the Muir, Reid, and Hugh Miller. To the
Grand Pacific, Johns Hopkins, and Charpentier we ap-
proached so near as to obtain some information as to re-
FIG. 8. REMNANT GLACIER SOUTH OF HUGH MILLER INLET, FROM A
PENINSULA IN THE INLET.
The ice mass occupies a typical glacial trough, shaped by an ice current flowing southeast-
ward, or from the observer. Photographed June 10, 1899.
cent changes. Of the Carroll, Rendu, Geikie, and Wood
we had only distant views.
Mutr Glacter.— The Muir Glacier is not only the larg-
est of the group but the most accessible. It has been
FIG. 9. MUIR GLACIER.
Photographed June 9, 1899, from point on mountain spur at the east, a little lower than
point Z£, fig. 1o.
MUIR GLACIER 21
visited by many ship-loads of tourists; it has received the
chief attention of students of physical geography; and
much is known of its recent history. Muir’s notes and
sketches record the approximate position of its sea cliff in
1880, and photographic and instrumental determinations
of its outline were made by Wright in 1886, and by Reid
LEGEND
POSITION OF ICE FRONT
»~0288KKs FROM DESCRIPTION BY JOHN MUIR, IBSO
—-~—:—- FROM PHOTOGRAPHS BYG.F.WRIGHT, 1886
—w-mwe FROM SURVEY BY H.F.REID, JULY 26,1890
*+e+¢0% FROM PHOTOGRAPH SY H F.REID,SEPT.7,1890
—*—+— FROM SURVEY BY'H.F.REID. JULY 19,1892
FROM PHOTOGRAPH BY M.F.REI0,AUG.19,1692
———— FROM SURVEY BY HENRY GANNETT,JUNE 12899
reg
1880
Peet. lial
SCALE © 1000 2000-3080 ~=h000 = 8000 FEE?
FIG. 10. MAP OF NORTHERN PART OF MUIR INLET.
Showing position of front of Muir Glacier at various dates. Reid’s survey stations are
indicated each by a letter, dot and circle, with figures showing height in feet above mean tide.
A and B were the extremities of his base line.
in 1890 and 1892. During our visit the outline was
mapped by Gannett, who tied his work to monuments left
22 ALASKA GLACIERS
by Reid. The accompanying map (fig. 10) is copied from
Reid, with the addition of Gannett’s line showing the con-
dition on June 10-12, 1899."
From 1880 to 1886 the cliff retreated about 4,000 feet;
from 1886 to 1890, 3,300 feet. Between 1890 and 1892
there was an advance of 700 feet; between 1892 and 1899
a retreat of about 1,900 feet, nearly the whole of the
change occurring after 1894. The net retreat in nineteen
years was 8,500 feet, or 1.6 miles.
Although several of these surveys were quite accurate,
I have stated their results in round numbers, because
ereater refinement would tend to mislead. The forward
flow of the glacier probably varies little from day to day,
but the breaking away of the cliff is quite irregular and
the outline of the front continually changes. Besides this
change in local detail there is a general change of more
permanent character, to be described presently; and it is
probable that an important seasonal oscillation interferes
with the direct comparison of observations made at differ-
ent times of year. The average annual retreat of the ice
cliff for the four years preceding 1890 was 800 feet, and
for the following two years the average advance was 350
feet; but Reid noted in the summer of 1890 a retreat of
500 feet in 43 days (July 26-September 7), equivalent
to an annual rate of 4,000 feet. Again in 1892 he made
two observations 31 days apart (July 1g-August 109),
and these show retreat at the rate of about 3,500 feet per
annum; but the whole retreat in the seven following years
1 Reid’s map is pl. xcva in 16th Ann. Rept., U. S. Geol. Surv., part 1, 1892.
Gannett’s work was limited to the changed ice front and the resulting extension
of the shore line. Field notes and photographs show that there were associated
changes in the drainage of the gravel plains, but as these data are not sufficient
for the correct delineation of the streams in 1899 I have left them as Reid repre-
sented them. Some time before 1894 the northern branch of the western creek
found a shorter course to the inlet, reaching tide about three-fourths of a mile
nearer the glacier; and some time between 1894 and 1899 a similar change oc-
curred on the east side of the inlet.
MUIR GLACIER 23
was only 1,900 feet. It is therefore probable that the
summer rate of retreat is much more rapid than the winter.
While these considerations tend to qualify the figures
deduced from uncorrected observations, they do not affect
their general tenor. The application of a correction
for seasonal oscillation would diminish by a few hun-
dred feet the estimate for the total retreat from 1886 to
1890, and increase by a similar amount the estimate for
the total retreat from 1892 to 1899, but would leave un-
changed the general result that the retreat in nineteen years
has been more than a mile and a half, and that the general
retreat suffered at least one interruption, a small advance
occurring between 1890 and 1892.
The general change of contour mentioned above is of
peculiar interest because it was predicted by Reid. The
middle of the glacier ends in deep water, a maximum
sounding of 720 feet having been recorded, but at each
side of the rock trough the ice rests on a bank of gravel
rising above the water level. Observing that the surfaces
of these gravel banks descend northward beneath the
glacier, Reid inferred that with the progress of recession
lanes of sea water would soon be admitted between the
ice and the gravel; and having determined that the mar-
ginal parts of the glacier advance very slowly as compared
to the medial, he inferred that their cliffs would be carried
back with relative rapidity by the attack of the warm sea
water. As the map shows, these expectations have been
fully realized.
In bringing the record of the glacier down to the sum-
mer of 1899 the preceding paragraphs practically close a
division of its modern history, for a new epoch was intro-
duced only three months after our visit. On the 12th of
September the southern coast of Alaska was shaken by a
severe earthquake, and other shocks followed at intervals.
These greatly modified the condition of its tidal glaciers,
24 ALASKA GLACIERS
and the Muir, at least, has not yet, after the lapse of three
years, resumed its normal habit. Just what changes were
made we do not know, because ordinary sources of infor-
mation have been cut off and no student of glaciers has
yet made an investigation.
On July 29, 1900, O. H. Tittmann, Commissioner for
the United States on the International Boundary, visited
Glacier Bay on the tourist steamer ‘Queen.’ In the lower
part of the bay the main channel was so obstructed by
floating ice that the commander of the vessel sought for
an easier passage west of Willoughby Island, and finally
desisted from the attempt to approach the glacier when
opposite the mouth of Muir Inlet. Looking ahead it ap-
peared to Tittmann that the whole of Muir Inlet was occu-
pied by an ice pack, the ice being probably grounded and
stationary. Instead of being able to steam as usual to the
very front of the glacier, the vessel was turned back at a
point about ten miles distant. In the summer of Igor
tourist steamers were stopped by the pack at distances from
the glacier ranging from five or six to eight or ten miles.
In December of the same year a special trip was made by
the ‘City of Topeka,’ for the purpose of forecasting the
accessibility of the glacier for the excursion season of
1902. The way was then found comparatively open, and
the steamer approached within about a mile of the gla-
cier; but in the following summer the nearest approach
was to a point five or six miles distant.
These facts seem to show that the earthquake shock, or
shocks, not only set free a great quantity of ice, including
bergs of unusual size, but left the glacier in such condi-
tion that bergs were more easily detached in subsequent
years. The determination of the nature of that condition
will be of much interest to students of the physics of
glaciers. Joint systems in rock have been plausibly as-
cribed to the passage of earthquake waves, and it is easy
MUIR GLACIER 25
to understand that the comparatively weak and equally
brittle material of glaciers may be still more susceptible
to rupture by sudden strain. As the tension cracks inci-
dental to the flow of glaciers are quickly welded, except
near the surface, it would appear probable that earthquake
cracks in the terrestrial parts of a glacier have no perma-
nent effect of importance, but the case may be materially
different in the parts encroaching on the sea.
As heretofore known, the frontal wasting of Muir
Glacier has been chiefly by melting below the water-line,
and the ordinary bergs, produced by the shearing off of
the overhanging upper portion, have been of moderate size,
readily floating away. ‘The greater bergs which stranded
in the inlet after the earthquake may have been produced
by cracks which divided the glacier from top to bottom.
Reid Inlet.— Glacier Bay parts at its head into three
branches (fig. 7). The westermost division, Reid Inlet,
receives the Grand Pacific Glacier from the northwest,
the Johns Hopkins from the west, and the Reid from the
south, the three fronts circling in compact order about
the western or northwestern end of the inlet. In 1899
(as also in 1892) this was the region of most active berg
formation, and on the day of our visit, June 12, the float-
ing ice was packed so closely as to stop our progress —
with a rowboat — and we succeeded in reaching only the
Reid Glacier. With the use of a plane-table, a map was
made of the lower end of Reid Glacier, and imperfect
topographic sketches of the ends of the Johns Hopkins
and Grand Pacific; and the data thus obtained were after-
wards combined with the representations of the same dis-
trict by Reid’ and the Canadian Boundary Commission to
produce the sketch map in fig. 11?
1 Sixteenth Ann. Rept. U. S. Geol. Survey, part 1, pl. Lxxxv1, 1896.
*There is some confusion as to names of glaciers about the upper part of
Glacier Bay. Muir, the explorer of the region, gave manuscript names, some
26 ALASKA GLACIERS
In the original exploration of Reid Inlet in 1879, Muir
found it headed by a single great glacier whose ice cliff
spanned the fiord from wall to wall, being interrupted only
by a single boss of rock, half island, half nunatak. This
glacier he named the Grand Pacific. When Reid in 1892
found and mapped two great glaciers, besides a third of
moderate size, Muir wondered and was perplexed, for it
did not seem possible that he could have overlooked two
tidal glaciers; and it was not until he revisited the inlet
in 1899 that the mystery was solved. During the thirteen
years which had intervened between exploration and sur-
of which received newspaper publication. Reid, who made the first survey
(1892), adopted Muir’s names and added others, his nomenclature being first
fully published in 1896 ( Sixteenth Ann. Rept. U. S. Geol. Survey; text and
map). The Canadian International Boundary Commission, surveying the same
region in 1894, prepared maps witha different nomenclature. These maps, be-
ing primarily for the use of commissioners in connection with the pending
boundary question, have not been officially published, but they have been unoffi-
cially distributed and their data compiled in various maps.
The following are the discrepancies :
Feeid’s name. Can. B. Com. name.
Glacier reaching Reid Inlet from
the north. Grand Pacific. Johns Hopkins.
Glacier reaching Reid Inlet from
the west. Johns Hopkins. No name.
Glacier reaching Rendu Inlet. Rendu. Charpentier.
Glacier reaching Hugh Miller
Inlet from the south. Charpentier. No name.
Glacier reaching Queen Inlet. Carroll. Woods.
Glacier reaching Geikie Inlet
from the south. Wood. No name.
It would appear that the cartographer of the Commission had moved three
names — Johns Hopkins, Charpentier, Wood(s)—from the glaciers to which
they were attached by Reid, and given them to other glaciers, displacing the
names given to these others by Reid. No new names are added, and the dis-
placed names do not appear elsewhere.
Reid’s nomenclature is followed by the U. S. Coast Survey in chart 3095,
Glacier Bay (1899). The Canadian Commission is followed by the U. S. Coast
Survey in chart 8001, Northwestern coast of North America (edition of 1898),
and in chart 3091, Territory of Alaska, southeast section (1898). Otto J. Klotz,
an officer of the Canadian Survey, in the Geographical Journal (vol. x1v, 1899),
uses Reid’s name, Grand Pacific, in his text (p. 529), but in the titles to two
figures (pp. 527, 529) applies the Commission name Johns Hopkins to the
Grand Pacific Glacier of Reid.
Reid’s names have recently been adopted by the U. S. Board on Geographic
Names. See National Geographic Magazine, vol. x11, page 87, 1902.
REID INLET 247
vey the main trunk of the Grand Pacific had disappeared,
leaving three of its branches as independent tidal glaciers.
The name has been retained for the northwestern branch.
In 1894 the district was resurveyed by the Canadian
Boundary Commis- __ ieee
sion, and another ae es mY wea TOR
Gri i” iio
eves
record was made of Y and
<< ogre SS aor
Whe: Grand sPas WJ, a
cific in 1892 and
1894, as in 1879,
presented two
fronts to the waters
of the inlet, the 7 = V7 wp
eed ipa ghee A 8
island, but in. the FIG. II, MAP OF HEAD OF REID INLET.
later years a much Showing positions of ice front in different years.
Land areas are ruled.
larger part of the
island was laid bare. In 1899—as nearly as my distant
views enabled me to determine — the western and greater
arm of the inlet had eaten back into the glacier so as to
reach some distance beyond the head of the island and
approach the mainland at the northeast, thus isolating a
body of ice lying between the island and the mainland.
The arrangement of moraines delineated by the Boundary
Commission showed that in 1894 this body had ceased to
be replenished by the current of the Grand Pacific, so that
its complete wasting was a mere question of time.’ It is
possible that in 1899 it had become so far reduced as no
longer to touch the island.
1These moraines are beautifully shown in one of the Commission’s photo-
graphs: A. J. Brabazon, No. 45, vol. 14, p. 13.
28 ALASKA GLACIERS
The front of Johns Hopkins Glacier has suffered less
change since Reid mapped it, but there has been some
retreat. A comparison of photographs made in 1892 and
1899 shows that more rock is exposed at the south; and
a remnant of ice I could see clinging to the mountain side
at the north showed that the front had within a very few
years held a position several hundred yards more advanced
than in 1899. Its determined changes were so small that
no attempt has been made to express them in the accom-
panying diagram.
The remaining glacier of the three was indicated in a
general way on Reid’s map of 1892, but its lower end was
represented by a dotted line, implying doubt as to its pre-
cise position, and no name was attached. It was more con-
fidently delineated by the Boundary Commission in 1894.
As my map and photographs give such determination of
the position of its ice cliff that future changes can be meas-
ured, it seemed proper to supply Reid’s omission in re-
spect to name, and the Harriman Expedition adopted
the name Reid. I
am glad to be able to
illustrate somewhat
fully a feature bear-
ing a name so de-
serving of honor in
Alaska glaciology.
As already men-
tioned,the Reid Gla-
x cier was a branch of
FIG. 12. REID GLACIER; en See VIEW the Grand Pacific in
FROM THE NORTH IN 1894. 187 9, but not many
From a photograph by A. J. Brabazon.
years could have
elapsed before the recession of the latter made it indepen-
dent, and it is probable that its end then projected some-
what beyond the general line of the south wall of the
REID GLACIER 29
inlet. One of Reid’s photographs shows that in 1892
it had retired within the general line of the mountain
front. The Boundary Commission’s map places it outside
the position of Reid’s dotted line; and in 1899 it was a
half mile within the limiting capes. A comparison of the
Commission’s photographs* with my own indicates a re-
cession of about 1,500 feet in five years, accompanied by
an important modification of the character of the front.
The removed portion was part of an ice cascade, and
as there was little
change in the thick-
ness of the glacier,
the terminal cliff in
1894 was much
lower than in
1899.
I found three
masses of dead ice,
testifying to. the
former greater ex-
tent of the glacier.
One of these masses 3
rested on a small ne. 13. REID GLACIER ; DISTANT VIEW FROM
promontory just east THE NORTHEAST IN 1894.
of the glacier front.
A knob of marble is connected with the main mountain by
a comparatively low saddle, and on this saddle lay a body
of ice apparently several scores of feet in depth but almost
wholly concealed by stones and gravel. This was outside
the line of flow of Reid Glacier, and could only be a
remnant of the mass of the Grand Pacific when that
glacier occupied the full width of the inlet. It dated back
to a time when the conditions were as observed by Muir
in 1879, and its gradual melting had probably been in
From a photograph by A. J. Brabazon.
1Especially A. J. Brabazon’s No. 38, vol. 14, p. 11.
ALASKA GLACIERS
30
*STIQ?P AOI RTA SoVIns 9} Je pasivyo ApiAvosy ‘Istoel[s Supyaour
21} JO Javed St puUNoIZ910j S[PpIM UT Sse Avp oy, ‘sot JuBMseYs HO jLed Ur Burjsa1 A[quqord ‘{jeM Aa] [Va U1d}SaM 9q} JO SN[B} paJaAOo-MOUS B ST JY3TI ay}
ye punoiss10j 94} Ul ‘pnoyo Aq payve0u0d 219M sUTe}UNOM Sullapiog dy} JO s}imuMns dy} pus ‘Iaf0e[S 94} Jo pua taddn ayy, *yaaz oSz 03 coe MOY pasuBs
SPY $} pus ‘joa3 ogz‘b sek PIO 94} JO yYSueT ayy, ‘Avq 94} Jo sapis s}yisoddo wm101j YTS 901 pus Avq sues 9y} Sutmoys‘suoiuedmoo aie Si pus $1 ‘s8Iy
66g1 ‘zt aNOf ‘IsHMHLUON AHL WOU ‘UAIOVIO aIgau ‘FI ‘ola
: : Rasicy
¥%, ka
(aie at Se
bal ‘ a “A
. rr ee
31
REID GLACIER
*(6z a8ed) Ar0jstyq [eIOe]S [edo] 9Y} Jo d3v}s dT] IVS We 0} ULSUO[Aaq JuBUMIAI ddt JUeUSEIs SIDAOD } J°] 24} 3B puno13s910; dy} Jo yueqg
“MOUS ST, “Surjsem ATMO[S SI PUB DAOTH 0} PasEdd SEY YOTYAA Ja19e]3 94} JO JUeUMDI B ST IWS Oy} 12 HHS Sor 9714 94} Suturofpe sseur yep y ‘eismvo
24} Aq 74Snvo d19M VOOM UT jas [[eJ S}I SABA BUTI 94} pue s10Jeq Sno] Jou yr on} Mo1y poyied pey S1isqoor uy ‘br ‘3g 0} MarIA uOIUedmoD
*66g1 ‘z1 aNOf ‘IsVHHLUYON ZHL WOud ‘UaIOVIO aIau ‘SI ‘ora
|
|)
AN
32 ALASKA GLACIERS
progress for nearly twenty years. The other masses clung
to the walls of the trough occupied by Reid Glacier, and
were still continuous with the ice of the glacier, although
they had ceased to move. ‘They were simply portions of
the retreating glacier so well supported by the land that
they had not fallen into the sea when the deeper parts of
the ice stream were melted. They were partly covered
by gravel and other rock débris, but still showed faces of
white ice near their junction with the glacier. That on
the west side extended about 1,200 feet beyond the general
ice front, and the eastern mass was nearly or quite as long.
From these remnants it is inferred that there was a some-
what gradual shrinkage of the glacier after the record of
1894, and that it did not immediately assume the propor-
tions observed in 1899.
The width of the Reid at its débouchure is seven-eighths
of a mile, and the general height of its ice cliff about 100
feet. The frequent falling of ice masses during our visit
gave the impression that it was discharging bergs rapidly,
but the little bay before it carried less floating ice than the
open inlet beyond.
The data compiled in the map of the inlet (fig. 11) are
of unequal precision. The line representing the ice front
in 1879 depends largely on the recollection of Muir,
but his recollection is supported by notes and a landscape
sketch made at the time. The fronts of Grand Pacific
Glacier in 1892 and 1894 are believed to be close approxi-
mations, but the front in 1899 has much less authority and
may involve considerable error.
The total retreat along the axis of Johns Hopkins Glacier
in the twenty years preceding 1899 was about three and
a half miles, and the retreat of the Grand Pacific along
the line of its western distributary was three and a half
to four miles in the same period. Reid Glacier retreated
a half mile after its separation, the period being some-
BERGS $3
thing less than twenty years. In 1879 the Grand Pacific
had a total water front of over three miles; in 1892 and
1894 the separated glaciers presented a total front of more
than six miles, the exposure to the sea being progressively
increased up to that time. Afterward the length of front
underwent little change, and should recession continue
it will diminish. Unless the enlargement of the ice front
was compensated by shoaling of the water, the sea had
exceptional advantage for twenty years in its attack upon
the ice, and this advantage may have been connected with
the phenomenal rate of recession.
Bergs.—'The upper part of Reid Inlet in 1899 not only
contained more floating ice than any other portion of
Glacier Bay, but its bergs were of greater size than any
others we saw. The one pictured in fig. 16 was ascer-
=
i
7 “x as ee wr
Mira Tt u fr aw
a7
mi
Wm" itty,
FIG. 16. ROCK-LADEN BERG IN REID INLET.
Poo
af
™
by
ul
oe cre
-. ee We
ear nae Ng et age
Scale is given by a boat. The nearer face of the berg, black with embedded detritus, is
probably part of the base of the parent glacier. Photographed June, 1899.
tained to rise 76 feet above the water, and one of my
companions who landed upon it and walked from end to
end, estimated its length by pacing at 750 feet. Having
my eye gaged by these measurements, I was able to form
an approximate judgment of the size of other large bergs
seen; and I estimated the largest, which was approxi-
mately tabular and square in form, to measure 1,000 feet
on each side and to rise 1oo feet from the water. The
thickness was probably not less than 500 feet. These
34 ALASKA GLACIERS
dimensions raised questions as to the mode of calving.
Reid, from studies of the Muir, inferred that waste along
the ice front was chiefly from melting by sea water; and
this melting, in combination with the forward flow of the
ice, produced an overhang, resulting in the breaking away
of the upper portion of the glacier by its own weight.
Such observations as I was able to make at various ice
cliffs were in full accord with his view, and the great
bergs of Reid Inlet may perhaps have been formed in that
way; but their size led me to wonder whether another
process might not be involved. Many of the immense
bergs of the Antarctic Ocean are tabular in form, and it is
believed that they have the full thickness of the parent
glaciers, which were protruded into the sea until actually
floating upon its surface before the separation took place.
In order that the Grand
Pacific or the Johns Hop-
kins should produce
bergs of this type, it
would be necessary that
the depth of the fiord in
front of the ice cliff
| should be not less than
seven-eighths the thick-
ness of the glacier.
Hugh Miller Inlet: —
Hugh Miller Inlet oc-
“no cupies an irregular re-
WM rar pio™ Gps ‘Ma cess among the hills and
FIG. 14. MAP OF HUGH MILLER INLET. mountains on the south-
Showing positions of the ice front in different westside of Glacier Bay.
years. Land areas are ruled. Rocky islan ds o f mo der-
ate elevation half block its entrance and interrupt its sur-
face. Charpentier Glacier reaches it from the south, ter-
minating in a low ice cliff about seven-eighths of a mile
HUGH MILLER INLET 35
broad. The Hugh Miller, descending from the moun-
tains at the southwest, spreads into a broad field north-
west of it, and has a double discharge, one part coming
eastward to the inlet, and the other going northward
toward Glacier Bay. ‘The face toward the inlet is about
three anda half miles long. The southern third overlooks
the water in a low cliff, and the remainder presents a
sloping surface black with accumulated rock débris.
Though the land-locked inlet gives the floating ice scant
opportunity to escape to the open bay,-very little was ac-
cumulated at the time of our visit, June 11, and all the
bergs were small. |
FIG. 18. TILL LEFT BY HUGH MILLER GLACIER BETWEEN 1880 AND 1890.
Photographed in 1899. The till is thin, but contains remnants of ice, and was englacial in
part. The single bush visible, almost the only vegetation on the new ground, is a willow.
The dates of exploration and survey are the same as for
Reid Inlet and the general history of change is strictly
parallel. Muir observed but a single glacier, to which he
gave the name Hugh Miller. Reid found two, and added
the name Charpentier. With the aid of Reid’s map I was
able to indicate somewhat definitely the extent of the sub-
sequent recession, and Muir, in revisiting the locality with
36 ALASKA GLACIERS
me, was able tosay that the change previous to Reid’s survey
was greater in amount than the more recent modification.
But after the lapse of twenty years Muir found it im-
possible to recall the precise position of the ice front in
1879, and a subsequent study of his notes and sketches
left the matter still in doubt. On the accompanying map
(fig. 17) I have drawn two tentative lines, one crossing the
inlet near its mouth, the other running northward from
the peninsula which margins the Charpentier Glacier.
The more conservative of these implies that the face
of Hugh Miller Glacier retreated about one and a half
miles between 1879 and 1892.
In 1892 Charpentier Glacier had two fronts, separated
by its contact with a broad rock island or peninsula. One
front, facing northward, was tidal; the other, facing north-
eastward, was non-tidal, but ended close by the water.
wren : paul ia . ee rt ' i eee
‘Oia
i} | Hh
Its surface was dark from the accumulation of rock débris,
and its motion had probably ceased. Seven years later
the tide-water front had retreated about one-third of a
mile, thereby nearly severing its connection with the inert
mass at the northeast (D, fig. 19), and the waste of the latter
ill
weal hi
FIG. 19. CHARPENTIER GLACIER IN JUNE, 1899.
t
HUGH MILLER GLACIER 37
had progressed so far as to render its surface almost black
from the accumulation of residuary moraine stuff. These
relations are indicated in figure 17. The condition in
1894 was intermediate between those of 1892 and 1899.
A comparison of Reid’s photographs and mine shows
also that the Charpentier had lost in thickness as well
as area, the lowering near its front being estimated at
about fifty feet.
As mapped and described by Reid, Hugh Miller Glacier
rested at one point against an island, and only the portion
south of the island yielded bergs. The northern division
of the front descended to tide-water, but was covered at
its margin by débris and had no cliff. In 1899 the front
had retreated so as to open a narrow channel west of the
island and expose the top of another island on which a
tongue of the ice rested. South of this point the ice cliff
had retreated westward to an average distance of 1,000
feet, the maximum being nearly 2,000 feet. It still
yielded bergs, but sparingly, and was probably approach-
ing a non-tidal condition. A large nunatak at the south,
which was mapped and photographed by Reid, was more
fully exposed than before, and a small one had appeared
between it and the ice cliff. Near the northern end of
the cliff the distortion of dirt bands and an uprising of the
surface of the ice suggested that another rocky islet would
soon be exposed. The retreat of the northern portion of
the glacier face had laid bare a group of rocks projecting
slightly above the water, and a larger rock knoll was
gradually emerging. At one point it projected as a nun-
atak about 150 feet above water-level, and farther on was
revealed at the water’s edge. The average width of the
space here abandoned by the ice is about 1,500 feet.
(See pl. mt.) The condition in 1894, as indicated by
photographs, was intermediate, but nearer to the condition
in 1899 than to that in 1892.
38 ALASKA GLACIERS
At the northern margin of the Hugh Miller ice field,
where it discharges toward Glacier Bay, there is some-
what similar evidence of retreat. Muir’s sketch shows
that this front reached tide-water in 1879, but was inter-
rupted near its eastern margin by a small island. This
detail serves to fix its approximate position as represented
in fig. 17. Reid states that at the time of his survey it
was non-tidal, but his map places the ice margin at the
water’s edge. Photographs made in 1894 indicate a bare
tract 1,500 or 2,000 feet broad between the ice front and
the strand, and at the time of my visit the distance was
2,600 feet, the surface being chiefly occupied by ground
moraine. The ice front in 1899 had a gradual slope, was
covered by drift near its margin, and was traversed by a
large medial moraine. Close to its front it received a
tributary, cascading down a narrow valley from the west.
The total retreat of the ice front at this point was prob-
ably a little less than one mile in twenty years.
Getkie Inlet.— Exploring Geikie Inlet in 1879, Muir
found it headed by a tidal glacier, to which he gave
the name Geikie. His notes estimate its width as several
miles, but do not serve to fix the position of its front. In
1892 Reid found that its front had receded so far as to
convert its two branches into distinct glaciers. Retaining
the name Geikie for the more northerly, he called the
other Wood Glacier. The Geikie was tidal; the Wood
barely touched the water at two points, but yielded no
bergs; and the nearer corners of the glaciers were con-
nected by a short body of motionless ice. Photographs
made by the Canadian Boundary Commission in 18947
show that in the two years elapsed since Reid’s survey
both glaciers had shrunk, the Wood receding several
hundred feet and the Geikie about half a mile. The
1A. J. Brabazon, Nos. 32, 38, 39 and 40, contained in volume 14 of the official
album, pp. 9, 32 and 33.
LA PEROUSE GLACIER 39
Geikie was still tidal. The two were still connected by
stagnant ice, a long, narrow strip, partly protected from
melting by moraine stuff. In 1899 we failed to reach the
head of the inlet, so that my only contribution to its his-
tory consists in assembling the observations of others.
LA PEROUSE GLACIER
Fairweather Range, which bounds Glacier Bay on the
southwest, presents its other face to the open ocean. Its
seaward face is bold and lofty, and the greater part of it is
above the snow-line. While rugged in detail it is little
complicated by foothill ranges, and from the ship’s deck
we could trace a number of its long glaciers from end to
end. Between its base and the sea there is usually a
narrow foreland, but this disappears toward the east and
broadens toward the west. At several points it gathers
the alpine glaciers into massive piedmont sheets, and
several of these approach or actually touch the sea. The
La Perouse, at whose edge we made a landing, is of this
type, being fed by alpine glaciers from the slopes of the
range about Mounts Crillon, D’Agelet and La Perouse.
FIG. 20. LA PEROUSE GLACIER, 1899.
Showing the alpine glaciers that feed the plateau mass below; and the relation of the
timbered ridge at the left.
Its extent in the direction of the coast is about three
miles, the central portion ending in a lofty white cliff.
The eastern third is darkened by a covering of moraine
and appears to be separated from the water by a strand.
40 ALASKA GLACIERS
The western part is partly concealed by a timbered ridge
running parallel to the coast (fig. 20). This ridge, which
is probably a huge moraine of Pleistocene age, extends
westward far beyond the end of the glacier. Our landing
(June 18) was at the western end of the ice cliff, coincid-
ing with the eastern limit of the timbered ridge.
The ice cliff facing the ocean at this point has the gen-
eral appearance of the front of Muir Glacier, but its sub-
merged profile is different. Instead of deep water it
overlooks a shoal, from which boulders project here and
there and on which we saw small bergs stranded. Very
little floating ice was visible, and no large bergs. The
cliff is evidently sapped at base by the wash of the waves,
and the process which perpetuates it is closely similar to
the process which main-
tains rock cliffs along other
portions of the coast.
The glacier, which farther
west presses against the
timbered ridge, flows past
its end to the sea, and thus
the extremity of the ridge
occupies a reentrant angle
in the margin of the glacier.
FIG. 21. ere MAP OF MARGIN OF Close to the angle a stream
LA PEROUSE GLACIER. of water, escaping from the
ssanicemea crams mast tie vin of glacier, has crossed the
trees. Forest is indicated by stars, sandbeach ridge, eroding a deep gash,
by dots. Approximate scale; 1 inch=2,000 feet. s
in whose walls the structure
of the ridge is revealed. The walls are not clothed by
vegetation, but are somewhat cumbered by the trunks of
forest trees fresh-fallen from the crests on either side. The
stream has been very active within the last decade or two,
and it seems probable that all its work of erosion was
1If our visit was at high tide, this shoal may have been bare at low tide.
s
LA PEROUSE GLACIER 4!
performed within that period. The section it exposes
(fig. 22) includes horizontal beds of blue clay, flanked on
the seaward side by highly inclined beds of similar clay
alternating with layers of sand. Both these are truncated
above, and
overlain un-
conformably
by a series of
horizo ntally FIG. 22. SECTION OF TIMBERED RIDGE NEAR
bedded gray- LA PEROUSE GLACIER.
4 Ss A, laminated clay. 2B, bedded clay and sand. C, bedded gravel,
els, in which with angular boulders and trunks of trees. D, bouldery till, with
are incorpo- tree trunks. G, glacier.
rated large angular boulders and trunks of trees. This
gravel is succeeded on the landward side by — and prob-
FIG. 23. BARREN ZONE AT MARGIN OF LA PEROUSE GLACIER (LOOKING SOUTH).
The glacier is at the right. Between it and the forest is a tract occupied by fresh drift,
with sticks and logs. Photographed in June, 1899.
ably passes into—a bouldery till, which also contains
trunks of trees. The clays and sands evidently represent
an epoch when the coast was more deeply submerged than
42 ALASKA GLACIERS
now, but our meager facts include nothing to indicate either
the date of their deposition or the date and manner of their
deformation. The overlying gravel and till are clearly of
glacial origin, and the gravel was laid down at or near sea-
level. As itis now about 150 feet above the sea, it is evident
that there has been a change here in the relation of land
and ocean. The buried tree trunks tell of an advance of
the glacier over a tract that had existed as dry land.
FIG. 24. PUSH-MORAINE NEAR LA PEROUSE GLACIER.
The glacier is out of sight at the left (compare fig. 23). The moraine, here 1o feet high, is
crowded against forest trees, and includes crushed trees. Photographed in June, 1899.
The remnant of timber standing east of the stream val-
ley was separated from the glacier at the time of our visit,
by a belt of barren ground from 100 to 200 yards wide (fig.
23). This ground was occupied by bouldery till containing
bruised and macerated branches and trunk fragments, and
the margin of the timber showed unmistakable evidence
of recent attack by the ice (fig. 24). The till had been
LA PEROUSE GLACIER 43
pushed up into the forest, forming a heap several yards
in height, and stones and earth were mingled with trunks
of trees and other vegetal débris. It was evident that the
forest had recently extended somewhat down the slope
toward the present position of the ice, and that atemporary
enlargement of the ice field had crowded it back. This
had occurred so recently that a younger growth of trees
Y,
wS \
ss> *,*
OEE NY,
st fey? Wi VW pind
Wye’ &! : Verb
i . ac } £
yah ee f A :
ee ee
FIG. 25. LA PEROUSE GLACIER—CONTACT WITH FOREST IN 1895.
had not yet started on the morainic ridge. Some of the
overthrown trunks still retained their bark, though it had
fallen away from most. The wood of the trunks was
still sound, but some branches an inch and more in diam-
eter had become brittle, and leaves and smaller twigs had
fallen off. With the local woodman’s knowledge of the
rate of decay inan Alaska forest it would be possible to
estimate closely the date of the advance. To my inex-
pert judgment it appeared probable that it occurred within
the last decade of the century.
44 ALASKA GLACIERS
Since writing the last paragraph I have received from
the U. S. Fish Commission a photograph made from the
steamer ‘Albatross’ in September, 1895, and have repro-
duced it in figure 25. This shows that the ice at that
time was in actual contact with the forest.
In the standing timber, which comprises both spruce
and hemlock, and also among the overturned trees, are
trunks four feet in diameter, and during the whole life of
these trees—a matter of centuries—this particular spot
has been undisturbed by the ice. It is thus shown that
glaciation has here attained within a few years a maximum
not previously reached for centuries.
The locality of our visit records at least two glacial
maxima. As the older till contains tree trunks, it marks
an advance of the ice after an epoch of inferior develop-
ment. The mature forest standing on this till records
another long epoch of lessened glaciation, and the recent
advance asecond maximum. It is possible that the epoch
between the two maxima was of only a few centuries, but
evidence to be mentioned in another connection indicates
that it was much longer.
On our return voyage in July we passed this part of the
coast at a distance of several miles, and I was able to note
that the eastern margin of the piedmont division of La
Perouse Glacier lay parallel to a forest margin, with an
intervening belt of different color, presumably morainic,
about 200 yards wide. Similar belts were also seen about
the flanks of the next piedmont mass toward the east.
These facts indicate that the recent advance recorded at
one point on the front of La Perouse Glacier was an ad-
vance of the whole glacier, and render it probable that
the change was not confined to a single glacier.
The evidence from the crushing of the forest does not
tell us whether during the long period before the last ad-
vance the ice had approximately its present extent or ex-
YAKUTAT BAY 45
perienced an important minimum, but the latter history is
rendered probable by comparison with facts recently de-
veloped about other glaciers of the same mountain face.
Lituya Bay, fourteen miles northwest of La Perouse
Glacier, was explored in 1786 by La Perouse, who de-
scribed and mapped the principal glaciers descending to
it. Klotz has made a comparison of La Perouse’s account
with the condition found by himself in 1894 (fig. 74),
and shown that there has been a marked advance of the
ice in both arms of the bay, the western glacier encroach-
ing three miles on the water of the bay and the eastern
two and one-half miles." The foot of Brady Glacier,
twenty-five miles east of the La Perouse, was visited by
Vancouver in 1794, and from a discussion of his descrip-
tion Klotz concludes that the ice front was then at least
five miles less advanced than in 1894. Muir in 1880
found the margin of the Brady against a mature forest
whose territory it was invading. As the La Perouse lies
between glaciers of the same range which have experi-
enced a great advance, and as it has recently crowded
against a forest, the probability is that its history resembles
that of its neighbors and includes a great forward move-
ment during the last century.
YAKUTAT BAY
In the neighborhood of Yakutat Bay a foreland fifteen
to twenty-five miles broad separates the mountains from
the open ocean. The bay lies partly in the foreland and
partly among the mountains. The outer part, to which
the name Yakutat is more specifically applied, is nearly
twenty miles broad, but narrows toward the mountains.
The inner part penetrates the mountain district for ten
miles in a north-northeast direction, with an average width
1Notes on Glaciers of southeastern Alaska and adjoining territory. Geog.
Jour., vol. xIv, pp. 523-534, 1899.
46 ALASKA GLACIERS
of three miles, and then turns to the right at a sharp angle,
and, assuming the character of a narrow fiord, runs back
thirty miles toward the south-southeast (fig. 26). It then
passes from
the moun-
tains to the
foreland, and
ends in an oval
expansion
three miles
wide. The
shorter and
broader reach
within the
mountains is
called Dis-
enchantment
Bay; the long,
narrow arm,
Russell Fiord.
Russell Fiord
has two east-
FIG. 26. MAP OF YAKUTAT BAY AND ITS DEPENDENCIES.
Based on map of the Canadian Boundary Comniission, with local ward branch-
details by I. C. Russell and Henry Gannett. es. The north-
ern is at the present time about eight miles long, ending
at Nunatak Glacier, and it is convenient to call it Nunatak
Fiord. The southern, about one mile in length, leads
toward Hidden Glacier.
The foreland southeast of the bay is in general low, but
includes hills and ridges of morainic aspect. So far as
known, it is wholly constituted of till and gravel, brought
by glaciers and associated streams of water when the ice
fields of the region were more extensive. Northwest of
the bay the foreland is occupied (or constituted) chiefly
by a great piedmont glacier, the Malaspina, the ice being
YAKUTAT BAY 47
separated from the water of the bay by a belt of detrital
lowland. The mountain system is lofty, and among its
summits are great tracts of névé. From these a series of
alpine glaciers stream down to feed the Malaspina, and
others reach or approach the land-locked arms of Yakutat
Bay. Turner Glacier, entering Disenchantment Bay from
the northwest, flares at the end after the manner of the
Davidson, but has not yet surrounded itself by a moraine
barrier, and ends in a berg-producing cliff. The Hubbard,
coming in two principal streams from the north and with
minor afHluents from the east, reaches the sea at the junc-
tion of Disenchantment Bay with Russell Fiord and
- occupies the coast for more than five miles. Nunatak
Glacier flows northwestward to the end of Nunatak Fiord,
where it maintains a discharging cliff nearly a mile broad.
Hidden Glacier, with branches from the east and south,
follows a trough parallel to Nunatak Fiord, but fails to
reach tide-water, being separated from it by a gravel-plain
two miles long. |
Two islands should be mentioned here, not as importan
geographic features but as landmarks to which the follow-
ing pages make occasional reference (see fig. 27 and pl.
vit). Haenke Island, a rounded rock knoll several hun-
dred feet high, lies near the east shore of Disenchantment
Bay. Osier Island, lower but containing also a nucleus
of rock, stands at the entrance to Russell Fiord.
The inner arms of the bay were explored by Russell in
1890 and 1891, and he prepared a sketch map showing
the general relations of fiords and glaciers. The shores
were afterward surveyed by the Canadian Boundary Com-
mission (1895), and during our visit Gannett made local
maps of the upper part of Disenchantment Bay and the
ends of Nunatak and Hidden glaciers.
The prevailing rocks are friable sandstones and partially
altered shales, and these are weathered and eroded much
48 ALASKA GLACIERS
more readily than the rocks about Glacier Bay. For this
reason the finer details of ice sculpture are preserved only
on surfaces from which the glaciers have somewhat re-
cently retreated. It is probably because of the rapid
weathering that vegetation occupies ice-freed surfaces
rather quickly, but this remark applies only to herba-
ceous plants and to willows and alders having the habit
of bushes. The spruces, whose dense forests cover the
detrital foreland east of the bay and climb the seaward
slope of the adjacent mountain, have accomplished little
toward the invasion of the most freshly glaciated faces of
the same mountain which are turned toward Yakutat Bay
and Russell Fiord.
So far as known by direct observation, the recent glacial
history is one of waning and retreat. From a careful
compilation of early records, made by Russell, it appears
that Malaspina in 1792 and Vancouver in 1794, attempting
to penetrate Disenchantment Bay in boats, found a glacier
front at Haenke Island. This was essentially the face of
Hubbard Glacier, to which the Turner was then trib-
utary. Completely filling the head of Disenchantment
Bay, it acted as a dam separating Russell Fiord from
Yakutat Bay, and the fiord was then occupied by a lake.
The discharge of the lake must have been southward over
the gravel lowland, and during its existence the wash of
its waves produced beaches which are still to be seen as
terraces about the southern part of the fiord. Russell
estimates their height above tide-water at 150 feet.
From 1792 to 1899 the face of Hubbard Glacier re-
treated about five miles, but there is no reason to suppose
that its position in the days of Malaspina represented a
maximum. Haenke Island, which was not wholly cov-
ered by the ice at the time of Malaspina’s visit, neverthe-
less preserves glacial striation over the whole of its crest,
and in places even polish; and this could hardly be the
YAKUTAT BAY 49
case if it had been exposed to the weather for more than
one or two centuries. Moreover, there is no change in
the vegetation at this point. The alder thickets which
begin at the head of Disenchantment Bay, characterize
the slopes of the mainland not only to Haenke Island but
for miles beyond, and the first spruces noted were not less
than five miles to the south of the island. But while the
ice seems to have recorded neither a maximum nor a pro-
longed lingering at the point where it was earliest observed,
our present data suggest no other line of critical impor-
tance. We can only say that for a period considerably
greater than a century the general character of ice change
has been diminution.
Since the last paragraph was written, the U. S. Coast
and Geodetic Survey has published a new chart of Yaku-
tat Bay, giving soundings from the ocean to Point La-
touche, six miles below Haenke Island. These sound-
ings give no indication of a moraine in the vicinity of Point
Latouche. Not far from that point there is a depth of
1,000 feet, and thence southward the channel is shown for
five miles. Here, at a distance of twelve miles from
Haenke Island, is a submerged bar with a depth of about
300 feet, and this is probably the last-formed important
moraine in the bay. There appears to be another oppo-
site Knight Island, seventeen miles from Haenke Island,
the intervening hollow having an extreme depth of about
600 feet (see fig. 27).
This is the greatest distance to which the channel of
the Hubbard, or Disenchantment Bay Glacier can be
clearly distinguished. Its course is not central to the bay
but nearer the eastern shore, the Disenchantment Bay
stream apparently having been crowded over by the ex-
pansion of the Malaspina Glacier, which then included the
Lucia. Farther to the south and southwest the soundings
reveal a series of troughs and ridges whose trend and
50 ALASKA GLACIERS
curvature suggest that they are connected with earlier
positions of the margin of Malaspina Glacier, and these
corrugations end against a great shoal which spans the
mouth of the bay from cape to cape. This shoal is
slightly convex toward the ocean, and its submergence
ranges from 50 to 80 feet. It is believed to mark a former
extension of the seaward face of Malaspina Glacier.
DEPTHS IN FEET
[je
— 150-300
== 300 - 450
450 - 600
600-750
750 - 800
900-1050
are —
FIG. 27. MAP OF YAKUTAT BAY, SHOWING CONFIGURATION OF BOTTOM.
Adapted from U. S. Coast Survey. Places where no soundings were made are indicated by ??.
All or nearly all of these ridges are probably connected
with the Pleistocene history of the region, but the moraine
RUSSELL FIORD 51
midway between Point Latouche and Knight Island may
correspond to a comparatively recent maximum of the
Disenchantment Bay Glacier—that from which it was
retreating when observed by La Perouse. <A more intel-
ligent judgment can be formed when the system of sound-
ings shall have been carried through Disenchantment Bay.
Turning attention to Russell Fiord, we find pertinent
phenomena somewhat more abundant, and it seems pos-
sible that their careful study may yield important chapters
of the local history. The lower parts of the fiord walls
are finely sculptured, showing by magnificent flutings that
there has been much longitudinal scouring. At various
points, but especially south of Hidden Glacier, there are
marginal banks of gravel similar to those about Muir
Glacier, characterized by horizontal bedding but showing
by their surficial forms that they have been overridden
and molded bya glacier. Nearly all parts of the walls of
Russell Fiord carry vegetation, of which the alder is a
conspicuous element, but the growth is relatively sparse
toward the north and dense and luxuriant toward the
south. The gravels about the basin at the extreme south-
ern end bear a luxuriant and mature forest of spruce.
Looking back to the time when Russell Fiord was filled
by a glacier, it seems evident that the ice stood for a con-
siderable period with a front just outside the mountains.
The expansion of the fiord in the edge of the foreland
corresponds, I conceive, to the flaring end of David-
son Glacier, and the surrounding plain of gravel is the
equivalent of the moraine barrier which the Davidson has
built in Lynn Canal. This condition is assumed to date
back several centuries, for it is not probable that the
forest could occupy the whole surface of the gravels until
the ice had retreated. The banks of gravel within the
fiord record lingerings of the ice front and subsequent re-
advances, but whether these oscillations preceded or fol-
52 ALASKA GLACIERS
lowed the epoch when the entire fiord was filled with ice
is a matter of doubt.
Coming to this region while the features of Glacier Bay
were fresh in mind, I searched gravel and till, wherever
opportunity offered, for vestiges of earlier forests which
might have been overridden by the glaciers, but the search
was unsuccessful; and so far as my evidence goes, the
condition of expanded glaciers observed by Malaspina
and Vancouver may not have been preceded in this
locality and in recent geologic times by a condition of
relatively contracted glaciers such as now obtains. Rus-
sell found a buried forest under the foreland gravels at
the south end of Russell Fiord,’ but the demonstrated
oscillation need not have been of great extent.
flidden Glacier.— The valley in which the distal part
of Hidden Glacier lies is a characteristic glacial trough
with rather uniform cross-section. Its course curves from
northwest to a little south of west, and it joins Russell
Fiord at right angles. In 1899 for a distance of a mile
and a half it was occupied by tide-water with a width of
three-quarters of a mile; then came a tract of gravelly
alluvium, nearly two miles long and a little narrower than
the inlet. The glacier itself had a width of a mile. The
ice front sloped gradually down to the alluvial plain, and
although the profile was slightly arched, its greatest de-
clivity (measured on a photograph) was only ten degrees.
In the lower mile the surface was remarkably smooth and
there were no important crevasses. There were lateral
moraines, and near the southern of these a single strong
medial, but the general face was exceptionally free from
drift. Close to the front margin the ice was somewhat
discolored, but so nearly white as to suggest that the
lower layers, usually dark with englacial drift, were not
visible. That they really lay at some distance below the
1Thirteenth Ann. Rept. U. S. Geol. Survey, Part 11, p. 89, 1893.
ee ee eee
BioddiseaoioslO nobbi
* Mioid Moeaus rort
aon alor Ts ansg 104% =.
gine b WT” Ls otgit ,
_ denasd yinoH yd boyorw
ist2 ils bas oldsi-onslq £ eBW
~.892 off bas tion! |
i orli 3% ,2noitiaoq ocd}
est
TD D NS GLACIER
ra Wie y> F ai ’
HAE ;VorIl
SCALE
ys Res Ae bats
| MILES
owed the 4 oh aw:
= + fatter of foul . e
Arr the rhs re aio
werw fresh mn ind, a searched gravel and t il, W
neortunity otferedy for vestiges of earlier : i rests
might have been overridden by me glacies iy be En e §
RS unsuccessful ; and so far as my avi ence :
dition of expanded glaciers 0 ia r ed a
4 Vancowver may not. have been. preceded it
cality and in recent geologic times bya condition |
vclarively contracted glaciers such: as NOW obtains,
) fowsd « buried forest under the foreland gravel
_ EXPLANATION OF PLATE Ive dem 101
i ‘tla Sy re Ppt haye been of great. extent.
Mt dabei tet he a o_o allt hel te
Hiden Glacier, Bord. the sea at spel thendk wat
ing from Russell F > Ww] ele.
map. For ‘hese
Bay, oh ee For
cord the ce Site 1
delta.
Offiée drawing ty Giles Gilbert
Tree Shee a
hough the atl was.slightly arched, its phe
clivity (measured on a photograph) was only ten deg
the lower mile the surface was remarkably smooth a
ere were no important crevasses. There were late
-aines, and near the southern of these a single stro
out the general feee was exceptionally free from
to the front mangin the ice was somewhat
seohored, but so measly wiite a8 to suggest that the
wer ja vers, analy dark + th — al drift, were. ne ie
Phat they wally legeat somme distance below. the | |
nae tus. Reet. TC. & Heclewaertep, Fart Wi) p 89, 1893.
i a
He
sani
é t x
Y @IVOS
adqIovly) NAAdAIH AO dV
AI 4Lv1g Re we TITAS WH
ne Oe oe re Len ae ey ee es ee ee a es ae)
a es
AMIOGe KAGE WO TAI
53
‘IIPeIS aq} Aq popots puv uapprz
~I9A0 U9Eq SBY YOM ued o}svM Japjo uv Jo JMVUMMIAI dy} ‘JaAvIS poyt}erjs A[OpNI SI 39] 94} IV ‘sIapR[s VAsely AURI YIM pozeloosse sured ajseM 4[INq
“Mv91}s ‘Ua1IBq 34} JO WOTSIRSNITI [VoIdA} & ST YS ye puL[Mo] ay, ‘aur au ‘19;9U]F JO z1ed J[qQISTA JO UIPIM “pnoyd Aq paTesou0d aie adUe SIP 9IIaI}.Xa 3Y} pus
SUTEJUNOME JO SPTMIMING }saAy}IOU 9Y} WioIy Uses aay SI yT ‘(92 “Sy pue Ar ‘{d 99s) ysva aq} moy ‘Avg jeynyAeA ‘piorg ppessny sayovoidde rapes ayy
‘6691 ‘oz ANAL ‘URIOVID NAACIH ‘ez ‘Ola
8
“k= rs ee es 8 SES Per
ae x SARE SPR ty
Yerkes wi
HIDDEN GLACIER
=
M2
oy ‘ WHA i \
Mi Py ff HUANG HAN
—
iN
\
\
54 ALASKA GLACIERS
visible glacier snout and were extended along the floor of
the valley beneath the gravel plain, seemed to be shown
by other phenomena. First, the water of ablation, though
flowing out from the surface of the glacier near each side,
did not visibly escape from the ice in the central part, but
oozed up through the contiguous gravels, gathering in a
number of streams, which attained their full size about a
quarter of a mile from the ice front. Second, the gravel
plain in the vicinity of the ice front was dotted by numer-
ous pits, the larger of which contained lakelets. The
sides of these pits were steep and exhibited the stratifi-
cation of the gravel in section, the pits having evidently
been formed after the gravel was deposited; and there
can be no doubt that they originated from the melting of
buried ice and the consequent sapping of the gravel bed.
The ice whose melting was thus demonstrated may have
been part of a continuous sheet or may have constituted
a series of isolated masses, but in either case each local
mass must have reached its position as part of the glacier.
The history seems to be, that the waning glacier was so
reduced by the wasting of its surface near its end that the
débris of its moraines, worked over by glacial streams,
overspread the ice and buried a wide belt. At the time
of my visit this was gradually and irregularly melting,
under the influence of underground waters, and by its
melting was sapping the gravel plain.
This process is of interest to students of Pleistocene
glaciology, because it is evident that with a slight change
of conditions it might lead to the formation of familiar
features of the ‘ modified drift.’ If the locality lay some-
what higher above tide, and if the glacier were so situ-
ated that, with the progress of its melting, the water of
ablation would be drawn off in some other direction, the
gravel plain would be left intact except for such changes
as resulted from the melting of the ice beneath it. Where
MH. A. BE. ¥OLiti
‘ie :
dless ree oH Isiraanen peat y
? to tisq vlsnigino stow esaenet 99% orld ban
ellsw qoote ot ilqensxs berriot-cdeort anole AWA AohAS od T
olitieg ori oals eworle 11 .noitose ni tieoqab leverg oft yaitididxs
elisw yollsv 2ti to s1utqluoe dioome ort ,19i28lg oft to ogole Isniccrrss
ry _ .611 bas 22 2og8q 990. yollsv gnignsd s to divom oft bus
-otlg omise oc} to ogete boonsvbs ees! & ewode swwos\ ~our0\ odT
to tizogab & bevisss1 toqe o1lt ,beonernenos bed gniliise 19ItA .norternon
Ive «
EXPLANATION OF. PLATE, V-
KETTLE-HOLES NEAR HIDDEN GLACIER
Kettle-holes are ascribed to the melting out of ice masses that had
been buried by the rapid accumulation of gravel or sand. In the
cases pictured the burying material was gravel washed from Hidden
Glacier, and the ice masses were originally part of the glacier.
The Upper Figure shows a fresh-formed example, the steep walls
exhibiting the gravel deposit in section. It shows also the gentle
terminal slope of the glacier, the smooth sculpture of its valley wall,.
and the mouth of a hanging valley. See pages 55 and 118. |
The Lower Figure shows a less advanced stage of the same phe-
nomenon. After settling had commenced, the spot received a deposit of
mud, and this mud was cracked as the settling proceeded. |
Photographed by G. K. Gilbert, June, 1899. Negatives Nos. 371
and 372, United States Geological Survey.
HM, A, Es VOL Il
PLATE
he T PLE-HOLE
INCIPIENT KETTLE-HOLE
HELIOTYPE CO., BOSTON.
KETTLE-HOLES 55
that ice was approximately or wholly continuous, its melt-
ing, being temporarily concentrated here and there by
underground currents, would let the gravels down un-
equally and leave them, in the end, in a system of irregu-
lar heaps identical with kames. Where the surviving ice
comprised only isolated or scattered masses, the waste of —
these would let down the gravels immediately above them,
producing steep-sided, crater-like kettle-holes, and creat-
ing the familiar phenomenon of a pitted plain.
The upper figure in plate v reproduces a photograph of
one of these fresh-formed kettle-holes, lying near the visi-
ble portion of the glacier. Its dimensions were 220 feet
by 70 feet, with a depth, to the water surface, of eight feet.
Its wall was divided at one point by an outlet channel
leading to a neighboring glacial creek. An incipient
kettle-hole seen about a mile below the glacier is repre-
sented in the lower figure. This had been overflowed by
water from one of the glacial creeks, so as to receive a
layer of mud, but the water had retired before it was
wholly silted up. It is evident that the meandering of
streams over the gravel plain would eventually obliterate
all of the kettle-holes, so that their preservation must de-
pend upon some permanent diversion of the streams.
The stream escaping from the north edge of the ice
front was traced backward to an ice cave among the hil-
locks constituting the lateral moraine. It was evident
from an examination of the local topography of the ice
surface that the débris had great influence on the rate and
method of wasting, and reciprocally, that the wasting
modified the distribution of the débris. Where the dé-
bris was more than a few inches thick it retarded melting,
producing an ice hill; but from these hills the stones slid
down to the neighboring hollows, producing accumula-
tions which in turn retarded melting and caused a new
distribution of hills. Some of the hills were elongate,
56 ALASKA GLACIERS
and may have marked the position of original moraine
belts, and one of these happened to be cut across by a
glacial stream, so as to be exhibited in section. In the
photograph reproduced in plate vi the ice, which is here
rather dark from suffused dirt, is seen to constitute the
mass of the morainic ridge, being preserved from melt-
ing by a relatively thin layer of fine drift.
Russell, who saw and named the glacier in 1891, did not
visit it, and merely records that it was non-tidal. His map
makes no claim to precision and can not be used in a com-
parative way to determine the history of change. Gan-
nett’s map, pl. rv, and the various photographs here repro-
duced, make a record which will be available for future
comparison, but inference as to past changes can only be
based on circumstantial evidence. That the recent history
of the glacier has been one of recession can hardly be
doubted. Not only do the kettle-holes testify to the stag-
nation and burial of what was formerly its snout, but I
found remnant ice masses above the gravel plain on both
sides of the valley. These were protected from rapid
waste by gravels that were originally parts of lateral
moraines, but as water was constantly flowing from them
their survival could not be indefinitely prolonged, and
their origin can not have been remote. They were not
seen more than a half mile from the ice front, but they
lay considerably above the neighboring gravel plain, the .
extreme height at the north being estimated at 300 feet,
and at the south somewhat greater. When the back of
the glacier reached to these heights its front probably
extended a mile farther down the valley.
The walls of the valley are not clothed with vegetation,.
but a scattering growth of annual plants and a few dwarf
willows have found foot-hold. The gravel plain through
which the glacial streams meander, though seemingly
affording conditions of soil and moisture congenial to
- i “Aas A be ly ay ed 4
= oat 7 i 4
~G : » ttl | | »bod
= sins
‘<a
ups
Q om -
dour enw slice otlt caadlyr omit 8 46 5 Aoizor 9 agi yd bovomer s19w atuqe
. ewon asd} tots!
r .88 s1git o1sqmos bas .s7 9e@nq 990
ae 208 .0% aviiKQoV 0083 (08 onus, tredliD .A 0 yd bodqurgotodd
x ove [sotgolos~ 291812 botial
3 fay ee (diane a0 vorrea® — .aavorl aawol
oe so sna orld to zogbin ot} 10 9m0 to stutonTa orl enol
: | ‘ ,O2.a98q 9% tinal? er MLA
el ~al'a tn a te .e ye -
Pee | rt, CO ON Lr vi Ji AINE
MEMIOTYPE ¢: BOSTOr
EXPLANATION OF PLATE VI
1
Upper Ficure.— PROFILE oF HipDEN GLACIER
Shows the relation of the glacier snout.in, June, 1899, to. topo-
graphic details of the south wall of the valley. . In the foreground are _
bedded gravels that have been overridden, eroded, and grooved by the
enlarged glacier, and are now being trenched by running water.
The amphitheater high in the mountain shows familiar forms of -
aqueous sculpture but is not continued downward ina gorge of com- §
- mensurate size. The gorge probably once existed, but the containing
spurs were removed by ice erosion at a time when the glacier was much
larger than now.
See page 52, and compare figure 28.
Photographed by G. K. Gilbert, June 20, 1899. Negative No. 368,
United States Geological Survey.
LoweER FiGureE.— SECTION OF MORAINE
Shows the structure of one of the ridges of the northern lateral mo-
raine of Hidden Glacier. See page 56.
Photographed by G. K. Gilbert. Negative no. 370, United States
Geological Survey.
» A;
~ast te .
. +2 oe ela
< a
Ee. YOu. il
_~
PROFILE OF HIDDEN GLACIER
SECTION OF MORAINE
HELIOTYPE CO., BOSTON.
HIDDEN GLACIER 57
arctic willows, was absolutely barren (fig. 29), and a sim-
ilar barrenness was observed on other fresh-formed streams
of glacial waste. The perpetual stream of cold air flowing
down from the ice above may be in part responsible for
FIG. 29. WASTE PLAIN OF HIDDEN GLACIER IN JUNE, 1899.
The rock fragments washed from the glacier are built into a delta plain, to which addition
is being made. In the foreground is an alluvial fan encroaching on the plain; in the dis-
tance, Russell Fiord.
this, but I conceive the chief cause to be rapidity of dep-
osition. The high grade of the plain, in comparison with
the breadth of its channels and the moderate coarseness of
its gravel, gave the impression that it was being built up
with great rapidity. —
As in Russell Fiord and its other appendages, the valley
walls exhibit the flowing contours of glacial sculpture in
magnificent development. There are many places where
the smooth curves of the mountain side, carved out in
harmony with the flow-lines of the ice, suggest the sweep-
ing contours of a gigantic ship, rather than the billowy
backs of a flock of sheep described by the word mou-
tonnée. A system of flutings can often be traced in sim-
ple curvature for a half mile, and no one familiar with the
58 ALASKA GLACIERS
topography resulting from stream erosion can fail to be
impressed with the profound modification here wrought
by the ice. (See fig. 102.)
As the extent of the glaciers has varied, masses of
gravel and other drift have been lodged here and there on
the valley walls and afterward overridden, and where the
subsequent action has not sufficed for their removal they
have been carved into forms harmonious and continuous
with the contiguous rock forms. Here and there, where
the rills of the valley wall have trenched these deposits
so as to expose them in section, one may see horizontal
bedding in a mass of gravel whose external surface ex-
hibits only the smooth curves of flowing ice. One of the
larger of these gravel masses lay close to Hidden Glacier,
against the lower slope of the north wall of the valley
(pl. v). Upon its sculptured back were scattered boul-
ders left by the ice which had recently overridden it,
and among them were a few great blocks of white granite,
brought from some distant source. Descending toward
the glacier, the surface of this gravel mass ran under one
of the remnants of unmelted ice to which reference has
already been made.
Nunatak Glacier.— Nunatak Fiord, like the fiord of
Hidden Glacier, has been boldly sculptured by ice. Its
lofty south wall descends steeply to the water and is com-
paratively simple in contour. The north wall is in gen- .
eral lower, is flanked by heavy masses of gravel and other
drift, and is interrupted by two branching troughs leading
over saddles of moderate height to the northern part of
Russell Fiord. These troughs seem to have been largely
shaped by the ice, which flowed through them to the
northwest. One is now bare, but the other contains an
ice mass with the habit of the dying glaciers of Glacier
Bay. ‘The mass receives a small tributary glacier near its
summit, but the end seen from Nunatak Fiord in 1899
+
m
ETO” BODY EV.
OE i ee = ae |
2 ~
. ‘ “ hy
EXPLANATION OF PLATE VII
Mar or NunATAK GLACIER
Nunatak Glacier reaches the sea at the head of Nunatak Fiord, an
arm joining Russell Fiord at right angles. See map of Yakutat Bay,
figure 26. ,
This map is based on a plane-table sketch by Henry Gannett, made
from stations on the north shore of the fiord, June 20, 1899. Special:
pains were taken to make record of the ice cliff terminating the north
arm of the Nunatak Glacier. Its south arm, and the minor glaciers,
were added from photographic data and eye observations, without the
aid of instruments.
Drawn by Gilbert Thompson.
See pages 58-63.
eyseis
te & *%* 0
XIVOS
HAIOVIO MVLVNON LO dVW
~
P/
-
=
~
+
arilf
4
WA aLvTg TT T9A “A VH
ee
pe a ae AS A en ate I se
.
cag tees ~ or Jigomeaee seine oe =
59
NUNATAK GLACIER
“AdT[VA Sursaey & JO YyNOUL 9y} Aq poysoSSns st YI JO JUS} xO
3T]} ‘WOITSOID DT 0} SINOJWOD TIOOMIS S}ISOAO PIOTY AVJVUNN JO[[VM IYI, ‘PIOWT []ossny jo [TV Jsam oy} 18 ‘pno[d Aq payesou0d A[jied ‘sure}uNOM jue SIP BL
*‘plOLY [[assny 0} pO AeyeunN wMop soo] pue ‘(+ -Sy) IF So}VUIWI9} YIYA YIP 94} IvsU ‘IaIOV[H AejyeunN jo pueg uleiowm vB UOSpUE}s I9AIISqO dT,
‘UHIOVID MVIVNON WOUT GUVMISAM ‘Of ‘OIA
TTT
: Hi A Wi
|
Lil I cats
| {ih 7 \\
yi i ; i
!
SS
h
{I
60 ALASKA GLACIERS
was probably stationary and wasting. It was heavily
coated with drift, which lay in irregular hummocks. The
opposite end was not identified, but may be one of the
branches of the stagnant portion of Hubbard Glacier, to
be described on another page.
Close to the end of Nunatak Glacier were two lateral
glaciers which may recently have been its tributaries.
LOO N\\|
FIG. 31. TIDAL FRONT OF NUNATAK GLACIER.
Beyond it, a hanging valley, with a small glacier. The heights are hidden by cloud.
Photographed from the southwest, June 21, 1899.
That at the north (fig. 31) occupied a trough trending
nearly east and west and intersecting the Nunatak at an
acute angle. It terminated several hundred feet above
the Nunatak, its lower part being buried under a heavy |
moraine. That at the south (fig. 32) probably occupied -
a yet higher valley nearly at right angles to the Nunatak
trough, but clouds cut off the view of its upper portion.
It was seen only as a series of ice cascades, pouring from
ledge to ledge for a thousand feet down the steep wall of
the trough.
The main division of Nunatak Glacier was tidal, dis-
charging bergs freely from a cliff nearly a mile long and
about 200 feet high. At the south the cliff ended against
a bold rock shore,
but at the north it
terminated among
gravels, and a nar-
row remnant of
ice, half buried,
extended several
hundred yards
west of the main
mass. Near and
east of the position
of the glacier front
is a high rock ter-
race against the
south wall of the
valley, and this
culminates at the
east in a bold
knob, thoroughly
smoothed and
rounded by recent
glaciation. Inthe
hollow separating
mass of ice of uncertain relations (fig. 33).
NUNATAK GLACIER 61
SSAA SEF
Sheers - 4 .
EE
—_ es
wn Sakis * Ves :
Ses ce a
S eeteall
FIG. 32. CASCADING GLACIER IN NUNATAK FIORD.
The visible portion of the glacier has no valley, but descends
wallof valley of Nunatak Glacier. Photographed June 21, 1899.
this knob from the south wall lay a
It was seen
FIG. 33. SOUTH TONGUE OF NUNATAK GLACIER IN 1899.
- only from the
west,and was |
supposed to
bea tongue or
distributary
arm of Nun-
atak Glacier.
The fact that
it lay several
hundred feet
higher than
62 ALASKA GLACIERS
the tidal arni has raised doubts as to the correctness of
the first impression, and I now suspect that it was only
the remnant of a former arm of the glacier, stranded as a
motionless and slowly wasting summit mass. On the map
of the Canadian Boundary Commission (1895) it is repre-
sented as a distributary of the glacier.
At the time of Russell’s visit in 1891 the glacier flowed
_on both sides of the high rock knob (fig. 34) and was re-
united beyond it, so as
to convert the knob into
a nunatak; and it was
this conspicuous nuna-
tak near the end of the
glacier which suggested
its name. The retreat
of the ice front in the
= Se ee Se intervening eight years
FIG. 34. TIDAL FRONT OF NUNATAK GLACIER. Call not have amounted
Photographed from the north, by D.G. Inverarity, to less than a mile and
June 21, 1899. The camera stood on the glacier.
may have been twice as
great. It was nearly all accomplished in the first half of
the period, for the photographs made by the Boundary
Commission in 1895' show a complete separation of the
two arms and a close approximation to the condition of
1899. ‘The tidal arm was perhaps a third of a mile more
advanced in 1895, but the non-tidal was not appreciably
longer. It is possible, however, that the latter extended
for some distance in a stagnant condition beneath a mantle
of drift, for at the time of our visit there appeared to be
remnants of ice ina moraine belt stretching for a mile be-
yond its extremity.
The accompanying map (pl. vir) is based on the sur-
vey by Gannett in 1899, supplemented by photographs.
It is accurate as to the ice front and contiguous land, but
1Nos. 20 and 45, on pages 7 and 17 of vol. 17 of the official album.
HUBBARD GLACIER 63
only approximate in its reproduction of the other portions
of Nunatak Glacier and the neighboring ice bodies.
Hubbard Glacter.— The Hubbard Glacier, discovered
by Russell in 1890 and named by him in honor of Gardiner
G. Hubbard, president of the National Geographic So-
ciety, is the most important ice body of Yakutat Bay.
Its width where it reached the bay was, in 1899, five and
one-half miles, its whole frontage, counting the sinuosities
of outline, being about six miles. Of this frontage the
southeastern third was motionless, and fringed for the
most part by a belt of morainic débris. The remainder,
pushing itself forward into the head of Disenchantment
Bay, maintained an imposing ice cliff nearly 300 feet high.
The active portion of the glacier had two main branches,
the larger coming from the east or northeast, the smaller
coming from the north, and the two uniting only three
miles back from the water. Looking up the valley, we
could see a number of minor tributaries descending from
the bordering heights, but the principal sources were con-
cealed from view, and the low grade of the main trunks
suggested that their beginnings were far away. ‘The sur-
faces of both branches were rugged, being divided by a
labyrinth of crevasses into a wilderness of pinnacles.
Morainic bands marked out the lines of flow, and a broad
belt of ice near each margin of the active portion was
black with included débris. The more southerly of these
belts was continued to the water front, causing a black
ice cliff nearly a mile in extent (fig. 35). The correspond-
ing belt at the north appeared to have become nearly sta-
tionary, as though resting on a rock shoal, and the flow-
lines of the northern arm were curved about it.
The southeastern third of the glacier was moraine
covered, not only at the water edge but for nearly or quite
two miles inland. The material was coarse and angular,
and was divided into zones or belts distinguished at a
ALASKA GLACIERS
64
‘XI puBIIIA saqetd sIVdMIOD “Ivy IOTIN J, |OUvySIp 94} UL
‘S}ITM PUB Uva] puodaq nq ‘d}SBA YOOI POPNOUT Y}IAA OV] SF }t Aqiean “Avg Jam yWEYOUASIG BAOgB 392J COL SI9MO} JoPOBIS 9} JO HHP 2t ouL
66g1 ‘1 ENaf ‘uaIOVIO auvasnH ‘Sf ‘old
7
y —a
be
-
*
=
HUBBARD GLACIER 65
distance by their contrasted colors— black, yellow, purple,
green, blue-black, and orange or rusty. These bands had
not the ordinary arrangement of parallel medial moraines,
but tended rather to contour the slope, and the search for
their origin and meaning would make an interesting and
profitable study. Some of them occupied ridges and others
hollows, suggesting inequality in their ability to retard the
melting of the ice beneath, but the whole surface was
rugged in detail, exhibiting a continuous series of hum-
mocks and kettles.
The map given in plate vi11 was made by Gannett from
a series of stations at the south, the northern shore of Dis-
enchantment Bay being inaccessible by reason of floating
ice; and some of the details, especially of the moraines,
were added by the aid of a series of photographs made
from a high station on the mainland near Osier Island.
Russell in 1891 (September 5) stationed his camera on
Osier Island; and a comparison of his photographs with
mine (June 22, 1899) shows that there was little change
in the general character and condition of the ice cliff. My
views place it one or two hundred feet farther back than
his, and this difference would probably be increased if the
proper correction for season could be applied (p. 22), but
in any case the estimate of the whole retreat would not ex-
ceed a few hundred feet, and would be very small as com-
pared to the retreat of Nunatak Glacier in the same period.
A photograph taken from Haenke Island in 1899 is also
comparable with one from the same station by the Cana-
dian Boundary Commission in 1895,' each showing the
relation of the northern part of the ice front to the features
of the contiguous mountain face; and in this case also the
recorded change is small.
Another series of photographs were made by the U. S.
Fish Commission in 1go1, chiefly from Osier and Haenke
1No. 13, on page § of vol. 17, official album.
66 ALASKA GLACIERS
Islands; these show a continuance of retreat. At a point
where a prominent moraine makes the comparison some-
what definite, the ice cliff appears to have then stood 700
to 1,000 feet farther back than in 1899. The cliff was
also shortened at each end by the enlargement of the
marginal belts of stagnant ice.
Turner Glacier.— Turner Glacier comes into Disen-
chantment Bay from the northwest, a few miles below
the foot of Hubbard Glacier. As already stated, it was
tributary to the Hubbard a century ago, and was ren-
dered independent by the retreat of the latter. Immedi-
ately after its isolation its front may have projected some-
what farther into the bay than in later years, but it is not
probable that the difference was great. A comparison of
Russell’s photograph made from Haenke Island in 1891
with my own made eight years later from the same station
(pl. x) shows no appreciable change in the position of
the front.
The general width of the glacier within the mountain is
about one mile, but it begins to flare before fully emerging,
and at the water front was nearly two and one-half miles
broad in 1899. For a width of about two miles an ice cliff
was maintained by the falling of bergs, and the cliff was
flanked on either side by a sloping tongue which, from our
distant view, seemed black. Russell’s picture represents
parts of these tongues as white, so that in these marginal.
portions a progressive change is recorded. There was
also a change in the flow-lines, as indicated by moraines
near the southwestern margin. A strand of the ice which
had previously swung far to the south had in 1899 ac-
quired a more direct course to the bay, reaching the cliff
1,200 feet to the northward. This would seem to indicate
that a body of ice near the south end of the water front
had in the interval become stagnant and, acting as an ob-
struction, had deflected the current.
WESTON
HELIOTYPA
EXPLANATION OF PLATE +X"
Uprer FicureE.—TuRNER GLACIER IN 1891
Photographed by I. C. Russell, September 5, 1891. | Negative No.
556, United States Geological Survey. 7
Lower Ficure.—TuRNER GLACIER IN 1899
Photographed by G. K. Gilbert, June 22, 1899. Negative No. 317,
United States Geological Survey.
Each of these photographs was made from near the summit of
Haenke Island, the stations being practically identical. The changes
in the glacier from 1891 to 1899 are discussed on pages 66-67.
The position of the glacier, on the west side of Disenchantment
Bay, is shown in plate vu and figure 26.
*“NOLSO8 ‘'O9D 3dALOIISH
6681 NI YSIOVIS YSNYNL
Bea
gi. ee on:
Meare ge eis!
L68t NI YSIOVID YANYNL
xX -3lvd Wl “IOA °3 °V CH
TURNER GLACIER 67
Since writing the preceding paragraph I have been able
to extend the comparison by examining photographs by
the Canadian Boundary Commission and the U. S. Fish
Commission. That by the Boundary Commission was
taken from Haenke Island* in 1895, its record being
midway between Russell’s and mine. It shows the con-
dition of each feature as intermediate between the phases
of 1891 and 1899. That by the Fish Commission was
taken from Osier Island in 1901. It shows an extension
of the frontal cliff, as compared with the condition in
1899, and probably indicates renewed movement in mar-
ginal ice which had become stagnant.
There is an important morainic belt on each margin of
the glacier, with outlying ribbons, and a single well-defined
medial moraine reaches the water front near its middle.
The visible portion of the glacier within its mountain
valley has a moderate grade, but at its débouchure into
the main trough of Disenchantment Bay there is a steep
descent, the surface falling 500 to 600 feet in a quarter of
a mile. The grade then suddenly diminishes to almost
nil, and the glacier terminates in a platform of nearly uni-
form height, with a width ranging in different parts (1899)
from 1,800 to 3,500 feet.
The ice cascade at the point of débouchure indicates a
drop in the rock bed where the Turner trough joins the
greater trough of Disenchantment Bay, and this feature is
related to the phenomena of hanging valleys, to which
special attention will be given in another chapter. The
flatness of the terminal portion of the glacier is a peculiar
feature, not so strikingly exhibited to us in any other in-
stance. It is of course possible that the longitudinal pro-
file of the glacier bed is here horizontal, and that the ice is
everywhere supported by a floor of rock or drift; but it
seems to me more probable that the flatness is due to
1 No. 12, on page 5 of vol. 17, official album.
,
68 ALASKA GLACIERS
flotation. If the glacier rested ona solid support there
would be retardation from the friction on its bed, and this
resistance would tend, under the laws of glacier motion,
to produce a surface gradient.
If it be true that the ice is floated, then the sea water
has access to its under surface, and the rate of melting is
greater than would obtain if the front only were exposed.
Should an increase take place in the supply of ice from
the névé, and consequently in the size and speed of the
ice stream, the end of the glacier would be thrust farther
out on the water of the bay, but this extension would in-
crease the surface exposed to melting, and the loss thus
occasioned would soon check the enlargement. The op-
posite result would follow a diminution in the supply of
ice, and the equilibrium between supply and waste would
thus be maintained without great modification of the form
and extent of the ice front. There would of course be
progressive modification from the silting up of the bay.
Direct melting of the under surface of the glacier before
the mass is broken up into bergs would tend to localize
the deposit of drift, so that the accumulation under the ice
would be quite rapid, and eventually the drift floor would
rey: ; reach up to the ice
Fey a
es ois mS Ch and subglacial melt-
Wy Z yy = oe ee ee ing would be
4, Wy Tipe Tae. (a ee
ae Y ~- 7: = -4) Checked,
ee oe a Ee Le If the glacier
floats, its thickness
FIG. 36. HYPOTHETIC LONGITUDINAL SECTIONOF can be estimated
TURNER GLACIER.
from the measure-
ment of the visible portion. In water of such density
as Reid observed in Glacier Bay, the ice of glaciers
floats with about seven-eighths of its mass submerged;
and the thickness of the visible portion of the tabular
mass in question would be one-eighth of the total thick-
OSIER ISLAND 69
ness. The central part of the Turner ice cliff in 1899 was
250 feet high, but as the surface of the glacier was greatly
dissected by crevasses its average height above water was
somewhat less and may be roughly estimated at 220 feet.
This would give for the total thickness 1,760 feet, and for
the submerged portion 1,540 feet. The theory that the
glacier floats, thus implies that the bay has a depth close
to the northwest shore of 1,600 feet, and the central depth
should be considerably greater. The theory could there-
fore be tested by sounding.
Oster Island.— The little island at the turn from Dis-
enchantment Bay to Russell Fiord (see pl. vir) is a low
knoll constituted of the altered shales of the Yakutat for-
mation. A rocky reef extends northwest from it, and a
gravel spit, bare at low tide, joins it to the mainland. It
has three faces, characterized by cliffs telling of active
erosion by waves. ‘The east face is turned toward Rus-
sell Fiord and receives the waves generated by southerly
and southeasterly winds in a straight stretch of deep
water nineteen miles long and from one and a half to two
miles broad. A high cliff testifies to their efficiency, and
so does the gravel spit just mentioned, to which they have
brought not only pebbles but large boulders. The north
face, which has a rock cliff of equal or greater height, is
turned toward the ice cliff of Hubbard Glacier, 6,000 feet
distant. The wind waves that reach it from Russell Fiord
have only two miles at most in which to develop. Wind
waves from the head of Disenchantment Bay, four miles
distant, might reach it, and on rare occasions they probably
do, but that part of the bay, being overlooked by the most
active part of Hubbard Glacier, is ordinarily full of floating
ice, which prevents the generation of such waves. Instead
of wind waves the chief attack is by ice-fall waves. From
four miles ofice cliff the bergs are breaking, and the cannon-
like boom recording the sundering of one of the greater
70 ALASKA GLACIERS
blocks came to our ears every five or ten minutes. As each
block fell, it started a series of circling waves, many of
which were so largeas to make breakers miles away, despite
the damping effect of the floating ice. The breakers we
observed on Osier Island were formidable enough to en-
force much caution in landing, and the series from different
ice falls followed one another so closely that there were
few intervals of quiet.
The southwest side of the island is sheltered from all
winds except westerly and, as it borders a cove which
westerly winds would pack with ice, may never feel the
force of wind waves. Ice-fall waves reach it from Turner
Glacier after a journey of four miles, and by shorter,
but deflected, courses from the Hubbard. Its shore
cliffs are much lower than those of the other sides of
the island.
In 1794, when Hubbard Glacier reached to Haenke
Island, Osier Island must have been ice-covered and sub-
ject to glaciation, and it was not bared until more than
half the subsequent wasting had been accomplished. It
is therefore probable that the existing shore cliffs, esti-
mated from memory as 25 to 30 feet high, have been
carved out within a few decades. During part of
this time the ice-fall waves reaching the north shore
were more effective than now because the ice cliff
was nearer.
From these various features, and especially from the
comparison of the north and east shores of the island, it
appears that ice-fall waves have very notable ability to
erode coasts, an ability fairly comparable with that of
wind waves. ‘This fact is of value to the student of Pleis-
tocene glacial lakes, as it enables him to understand the
clear outlining of their coasts in cases where the indicated
extent of the water surface is too small for the generation
of important wind waves.
SO Riate Xi 5 ee
fi
a Ae, " >
oe eh tang epee me IN ne eg nn
end al
ewe ee ee
MAM OF COLUMBIA GLACIER
= : ; . SOBUK ‘. ‘
——— es wae _ — Pei aed seh
ra a A! AS t
Mpc PaseiMe to Our ears ey:
Teh bei, tt started a Bee “6 ;
which were 50 kenge to eli
x GH pine fect of the iat: i
observed on Oeter Ishend were or id ) pera hegaee
force much autvon am das ling, veal the waries froma aitenent
ice falls followed oat esodifer a clowmy that: tere: were
few intervals of quiet, |
The southwest side of the land is sheltered Sci all”
_Winds except westerly and, as it borders a cove which —
westerly winds would pack with ice, may never feel the
rce of wiad waves, -Ice-dall, waves reach it from Tune
lacier alte APG OF ir?
bi mr deLeotenl, eae
clits are ee lever
olumbia Glacier reaches oe sea at t
or the el 6. ~Frinc ey Pek
end dee 1 | 9, tl rns
| | : fe ip:
Drawn by Gilbert Thompson. _ bead been uncannplicher 3 coat
Contour tele 250 feet. the hay a repagsentes | ab} ee |
At lowest tide tegen ys is mh 'o islands north of
red alon
flats, and extensive Shoals’ are ba 3 ;
glacier is described on. rt. Itis pictur
3 and XII, and in figure 37. 37. WAVES reaching the 4
re mare effective fs an now bécause the ice elit ce
5 cy.
—
rrom these various features, and ehipeedaliy from the
mparison ef the nerth and east shores of the island, it |
appears that hee-fall waves have very ‘notable ability to ee
erode coasts, an ability faitly comparable with that of @
wind waves. This fet is of value to the student of Plews
focene glacial lakes, as # enables him to understand the a
lear outlining of thelt eoasts in cases where the indicated 4
mt of the water surface is foo eemall for the generat a
MEPOTtant Witt waites,
H.A.E. Vou. Iil Puate XI
ce) | f
Hal bY ; wa
th k ' \ tims 1
in}: +2000 Be
[dy \L et ase
~ fl : \
See:
4 =
re
7
MAP OF COLUMBIA GLACIER
SCALE
o | 2 3 he 5 6
MILES
F
{
j
i
|
{
a a eel
ee ee
Le EMT MEL em
Ne aS Ban
. —— am ewe a ee ee
ee PP RE TTR Le I LA te RTM 6 EC IT, SMT rN men - Ta -~
i n
Misc tb?
PRINCE WILLIAM SOUND 71
COLUMBIA GLACIER
Between Yakutat Bay and Prince William Sound we
made no landing, and our course lay too far from shore
for observations of value on the glaciers.
Prince William Sound is an extensive and intricate
body of water, penetrating a mountain district. Its numer-
ous islands and peninsulas are mountain peaks or ranges,
and many of its inner arms and passages have the char-
acter of glacial troughs or fiords. Among the mountains
of the mainland at the east and west are many small gla-
ciers, and a great mountain mass at the north supports
extensive névés from which magnificent ice rivers flow to
its northernarms. It was my good fortune to be landed at
the mouth of one of these ice rivers and, in company
with Palache, Coville, and Curtis, to spend several days in
its study. Many photographs were made and some map-
ping was done.
In June, 1794, this glacier was seen from the mouth of
the associated bay by Whidby, one of Vancouver’s officers.
Vancouver says: ‘To the eastward of this is another
bay of rather larger dimensions, with an island in its
northeast corner, . . . terminated by a solid body of com-
pact elevated ice, similar to that which has been before
described ... 3; as they passed the eastern bay they
again heard the thunder-like noise, and found that it had
been produced by the falling of the large pieces of ice
that appeared to have been very recently separated from
the mass extending in vast abundance across the passage
. . . » insomuch that it was with great difficulty the boats
could effect a passage.” ?
The bay and island appear on a map in Vancouver’s
atlas (see fig. 42). The bay (without the island) is rep-
1A Voyage of Discovery to the Pacific Ocean and round the world, etc., Capt:
George Vancouver, vol. v, London, pp. 316-317, 1801.
72 ALASKA GLACIERS
resented on a map prepared in connection with expedi-
tions to Alaska under Glenn and Abercrombie, in 1898,
and the same map also indicates the presence of the glacier,
but neither bay nor glacier is delineated with sufficient
accuracy to serve as arecord for future comparison. The
name Columbia was given by the Harriman Expedition.
The general course of the glacier is southward, and its
width in the lower ten miles is from three and a half to four
miles. Its sources are distinct and were not seen, but
beyond the tract covered by our map (pl. x1) it appeared
to spread somewhat broadly, and the ice field affording
its chief oe may send streams in other directions also.
Wm Cen ve a
FIG. 37. PANORAMA OF COLUMBIA
Shows the western division of the front.
About nine miles from the sea it encounters an outlying
mountain over 3,000 feet high, by which it is divided, the
principal current passing to the west. The eastern arm
descends steeply for three miles and terminates in a -
land-locked valley against a plain of glacial gravel. A
subdivision of the western arm enters the same valley. In
1899 it barely touched the eastern arm, so that the moun-
tain was wholly surrounded by ice and could properly be
called a nunatak. Beyond this point the main stream
flowed to the ocean, but the surface grades descended
also toward lateral valleys, and there was waste all about
1Maps and descriptions of Routes of Exploration in Alaska in 1898. U.S.
Geological Survey, 1899. Map No. 8.
COLUMBIA GLACIER 73
the periphery. On the east side the ice rested against
three low hills, beyond which were lakes supplied in part
from its melting. In one place a lobe of ice touched one
of the lakes. Ina hollow on the side of one of the hills
a lakelet was imprisoned by the ice, one of its shores
being constituted wholly by the glacier. On the west is
an embayment among high mountains, into which the ice
sent a tongue two miles long, but there was no lake and
no visible outlet for the water, which must have found
its way to the sea beneath the body of the glacier. This
feature is specially remarkable from the fact that the sub-
glacial water could not follow the course of the ice, but for
vay NORTHEAST
a Z
>
v
O <P aa y 6
235 fe 2S es,
Ui Mi.. - ey
GLACIER, FROM THE SEA.
From photographs by W. H. Averell, June, 1899.
several miles must either move in the opposite direction
or take some independent route.
Columbia Bay, to which the glacier flows, is from four
to five miles broad and is locally divided by a group of
islands. ‘The western arm, two and a half miles broad, is
comparatively simple in outline and is probably deep. It
received the principal discharge from the glacier, which
spanned it from side to side with a cliff about 300 feet
high. The eastern arm, irregular in outline and judged
from the configuration of its shores to be comparatively
shallow, was bordered by the glacier for a mile and
a quarter, but the ice cliff was less lofty, and a compari-
son of its outline with other portions of the glacier showed
74 ALASKA GLACIERS
that the water controlled the form of the ice front to only
a moderate extent. The principal island of the group, to
which we gave the name Heather, is nearly three miles
long and has an irregular surface, rising at one point to a
height of 500 feet. It consists chiefly of rock. Several
lower islands lie north of it, and the ice front rested
against one of these for a space of 3,000 feet. The number
of islands varies with the state of the tide, and it is pos-
sible that all are united at lowest tide.
Opposite the great nunatak were two medial moraines,
one passing within a half mile of its base, the other lying
about one mile from the opposite edge of the glacier. A
central tract two miles broad was practically drift-free.
Toward the end of the glacier this central tract broadened,
the medials swinging toward the sides, until finally the
white belt was three miles wide. As the medials diverged
they also broadened, and they eventually merged with
flanking moraines, so that near the end, especially on the
east side, the areas of drift-covered ice were very wide.
The marginal belt on the west, instead of continuing north-
ward parallel to the medial with which it was associated,
was seen to curve about into the western embayment, as
indicated on the map, and a belt seen from a distance near
the north edge of the embayment was supposed to be its
continuation, a loop being made within the embayment.
As the ice in the embayment descended toward the west,
it is evident that the morainic loop could not at that time
represent a line of continuous flow, for we can not suppose
the ice to flow into the embayment on a descending course
and then return on a parallel ascending course. It is
therefore probable that the moraine was formed as a com-
paratively direct line of drift, following the course of
the main ice current at a time when no current entered
the embayment. The inference that a change has oc-
curred naturally leads to enquiry as to the precise nature
74
Tuet tre erat:
b@beseratc «x yeah, v |
which we nw the name Heather, ia: rly
Mong ar - at irregular surface, rising atone sailed fo a "g
height ry 506 feet, It consists chiefly of tock, ‘Several.
lower \siamets Tie north of it, and the ice! front rested —
against one of these for a space Of 3,400 feet, The number
of islands varies with the state-of Peeiserats it is at
sible that.all are united at lowest tide...
Opposite the great nunatak were two medial maonatniiny |
one passing within @ half mile of lee baer, the other lying’ F
about one mile from the o opposite edge of the glacier. A
centr a}
plate x1. cane r poy ae nannies a '
tive Nt + pho raph 8 py de by ES. bee aia ge Meee !
ne oth edgr anf Fee. cmbey meet was Borin © en its
continuation, Mp being made within the embayment.
As the ice in it embayment descended toward the west,
ic is evident that the morainic loop could not at that time
represent a line of continuous flow, for we can not suppose
the ice to flow into the embayment on a descending coursé
and then return on a- paralle! asecnding course, I[t-is—
therefore probable that the nae tere formed ms. a come
iratively direct née oof dei, # 13 Rn Tage the ¢Ourse of
ie main ice Gurréhf at a —_ ik: mo current.entered
i@ embayment. The. inferwses: that a change has-oce _ |
wel naturally leads to ers aigaetD the precise ee an
: =—s- an
4 -
ANYIS] WAHLYSEY Wows
oad 32 08719 .
BUAIOVIDH VWIAWNTOD
SI4HYND AG HdvVHOOLOHG
EFT Winatlnn kb
\
HX J31LV 1d WE 1TOA AWH
*») nee Naf \
iy i A
¥ A ,
ae AST,
Ry
7"
He
SAL ey be 4
\ Bt
bi 76 Fey
SAAR ak
PLA We
iy
mye
Rf
ta
Miouy
: va
‘
te
i
' “+
t«
a
! Lae 1
i sy
)
4
‘
t ’
j
t -. ;
a We
Yi ae vow
aa CS
Pye
Mo /
Vs
PORTE VAT AP AD
d Wai he ene
| A
\ EA Ti
j Yi
- ,
at
bd t
Pa
sy
’
“¢
t
3 .
4 ‘
‘
$
3
.
bs ‘
f
f
AS
\ ¢
“hus
ee
14
Dawe ie
i 7
,
.
. “peur . vs
We
~ th
F
:
\ ‘
COLUMBIA GLACIER 75
of the antecedent condition of the glacier. On the one
hand, the embayment may have been so full of ice that the
surface gradient was outward; or, on the other, the glacier
of the main valley may have had so low a surface that
there was no tendency to overflow to the comparatively
shallow side valley.
The first case implies snow accumulation in the embay-
ment a few decades ago at a rate not since maintained,
and would correspond to a general expansion of glaciers
followed in later decades by contraction; but the rela-
tions of the ice to the forest, to be described presently,
show that such contraction has not taken place. The
second case implies a general expansion of the glacier as
the important element of its later history.
Another medial moraine of the great ice field north
of the nunatak passed just east of the nunatak and
continued down the eastern arm of the glacier to its
end, where it contributed toward the building of a
great alluvial delta which was gradually obliterating one
of the lakes.
At the western margin of its principal tidal cliff the
glacier rested on a bank of drift at the level of low tide,
and this bank extended eastward as a shoal, on which
bergs were stranded, for several hundred yards from the
shore. A bank also extended eastward from the island
against which the ice front rested, constituting at low
water a stony cape half a mile long near the foot of the
ice cliff. These banks testify to a lingering, or linger-
ings, of the ice front near the position of its modern maxi-
mum, but it is not easy to estimate the duration of the
lingering. The western bank is built in deep water,
but may have been constructed rapidly, as the contig-
uous portion of the glacier is heavily charged with drift.
The eastern bank margins a part of the glacier front
carrying little débris, but occupies an arm of the bay which
76 ALASKA GLACIERS
was probably originally shoal. They may have been
formed recently, or at some earlier epoch.
The drainage of the ice included several streams
flowing eastward to the chain of lakes, and we noted
two important streams from the western ice cliff. One
of them issued from a cave at the water’s edge near
the western limit of the cliff, the other from a sub-
merged and invisible tunnel near the middle of the
cliff. The last mentioned was probably the largest of
all the draining streams. It rose to the surface at the
base of the ice cliff and flowed southward over the
salt water, forming a
broad lane of milky fresh
water with a visible cur-
rent and at times nearly
free from floating ice.
At most points the
forest of spruce and hem-
lock approached close
to the ice, its relation
being similar to that ob-
served at La Perouse
Glacier. At the western
FIG. 38. WESTERN EDGE OF margin of the main ice
COLUMBIA GLACIER. f :
Shows barren zone and forest. From a cliff, where the glacier
rock slope, there was a belt of bare rock, from 200
to 300 feet broad, between the ice and the forest
(fig. 38). This belt was strewn with fragments, not
only of rock but also of wood, and trees were freshly
overthrown at the margin of the forest. At the time
of its attack on the forest the ice must have been 100
feet deeper than in the summer of 1899, and it also
extended farther southward, as shown by a push-mo-
raine of rock at the water margin, 800 feet from the
COLUMBIA GLACIER "7
ice front (fig. 39). A second push-moraine, less massive
than the first, lay within it, being 160 feet from it at the
water margin
and elsewhere
nearer to it
than to the ice.
On the island
between the
two ice cliffs
there were FRE SSN ee A
also two push- FRRSO¢, SAAS a
moraines of MASc Se Se oe
FIG. - PUSH-MORAINE, WEST SHORE OF COLUMBIA BAY.
recent date, 39 ;
the nearer being about 100 feet from the ice front, the
farther from 300 to 500 feet. The latter was associated
with overthrown forest trees, and included with its rocky
FIG. 40. FLUTED MORAINE AT EDGE OF COLUMBIA GLACIER.
Photographed in June, 1899.
débris not only tree trunks and branches but folds of
peaty soil. The tract between the nearer push-mo-
raine and the ice was in places occupied by an old mo-
78 ALASKA GLACIERS
raine surface over which the ice had advanced, and this
surface was elaborately fluted in the direction of ice
motion, the corrugations having a vertical magnitude
of several feet (fig. 40). In one instance it was seen
that a large bowlder in the underlying drift had im-
pressed its form on the ice, preserving in its lee a train
of drift of the same cross-section, which constituted
a ridge, and it is probable that the other flutings were
of the same character. As these details in the con-
figuration of the drift surface would be quickly ob-
literated by frost and rain, their exposure must have
been very recent. Probably the advance creating the
push-moraine and the subsequent melting which laid
bare the ice-molded drift had taken place within one
or two years.
On the mainland at the east the same phenomena were
observed, with the exception of the fluted drift surfaces.
There was an inner push-moraine, chiefly or wholly of
drift and running parallel to the ice margin. There was
an outer push-moraine, less regular in its distance and
associated with disturbance of the forest and the meadow
peat (fig. 41).’ In the tract between the two many
prostrate trunks were seen, showing that in places the
front of the forest had been crowded back several hun-
dred feet. Many of the trees that were overturned but
not overridden, retained their bark, branches, and even
minor twigs, but the leaves had fallen. On disturbed
forest soil Coville found three young spruces which
had grown since the catastrophe. In each case the
age, as shown by rings of growth, was seven years.
The date of the ice maximum was therefore not later
than 1892 and may have been that year.
1The view in fig. 41 is toward the northeast — along the front of the push-
moraine. A little of the steep face of the glacier is seen at the left. At right
is a tract of undisturbed bog.
79
COLUMBIA GLACIER
‘90d ANV LSHUOA NO UAIOVIO VIAWN'IOD AM MOVLLV ONIMUVW ANIVUOW ‘IF ‘OTA
ny
if
ve ary”
in
NN
SS
WSs)
- ‘i ‘%
..
Y bas A
EY #
TI a
80 ALASKA GLACIERS
The overturned forest trees associated with the push-
moraines on the eastern and western shores of the bay and
on the island, exhibited the same general appearance of
recency, and there can be little doubt that they were dis-
turbed at the same time. ‘They demonstrate a temporary
increase in the size of the glacier, not of precisely the
same amount at all points, but of the same order of mag-
nitude. Previous to that expansion the glacier had been
smaller during a period at least sufficient for the growth of
the overturned trees. The evidence from forests and
push-moraines does not show whether the ice during this
epoch stood continuously near to the forest or was sub-
ject to wide oscillations in extent; but the bending of
the moraine belt on the back of the glacier into the
western embayment (page 73) gives strong support to
the view that the recent maximum was preceded by an
important minimum.
No attempt was made to estimate the age of the trees
by counting rings of growth, but the forest had the char-
acteristics of maturity, and the time required for its pro-
duction could hardly have been less than two or three
centuries. ‘The mountain side just west of the glacier,
rising steeply to a height of 2,000 feet, is clothed with a
luxuriant growth from the push-moraine up to about 1,500
feet. Many of the trunks are three or four feet in diam-
eter, and among them lie prostrate logs in a state of de-
cay. Upon the islands, and on the lowland near the east
margin of the glacier, the trees are somewhat smaller, but
the many dead trunks standing among them indicate that
they are mature, and their term of life may be as long as
that of their western neighbors.
A further item of information as to variation, albeit
somewhat indefinite, may be derived from Vancouver’s
map. It is not sufficiently precise to afford identification
of any topographic detail of the bay except Heather Island
us Nesey
are mately
oo ae
14 4 oA AKIVEA
a
ee ee me
A ee ec ee ect
nW « aoviad—. anvorl saa |
1 bane : cbawoe oft to hae rob aan
ines
es
ae he
4
r
4
, a
.¢
r
|
|
ia
aed forest trees,
uae stern and Bi:
nit ude P evious 0 ee at expane rn Dh.
smaller during a period at least su
ees OV wotecto trees, The ev
sa h-moraines does not show wh
s poch s poe con a neat t
et re Pn Wa am So
An index 5 the sound, showing. pos sitions of
Columbia Plc ased_ chiefly” on United § States Coast Su:
no
wae
3%
idence from
Z eee a . : 3
Bs as ne Base
des ~ eh eal
NO. 3091. he i tt) rae by te
“Lowen Fioune.—Skeren or
"Surveyed by. Henry Gannett, |
bert , Details al
cher, and an mong hese “fie pros strate S toek in a ste de
cay. Upon the islands, and on-the lowland near. gfe 3
argin of ¢ the glacier, the trees are somewhat smaller, 4
many dead trunks standing amon ¢ them indicate. hal
a re mature, and their tert. of i ide may be as. long |
2a~ Ail LAL
“their western ndighbe ese *
rther item of information ss © variation; all
t jj finite, may Be derived from Vancouy
ERR eo
uficien nth iy precise to ; ifford identification :
T8744}? . i 5 Te
ry EE a en
ok mos to popra hte detailef the bay except H eather.
- "F 7 » -
. oll
-HLA.E. Vou Ill : PuaTe XIll
Z —r ca
ra
,
yak 9
.!
Ay
Ra :
bad 147 7
PRINCE WILLIAM SOUND
GLACIER |
ah ied? iy
a
5) CRESCENT
GLACIER
NORTH
SKETCH OF PORT WELLS
AHOCEN &CO. BALTIMORE
’ . ct?
oye i SP
m « -
1 eet om
a ee
Pee ee wee wr
pear geet teneeers
y
a7)
xf tee ' are! io
: Ce eet RE
je Ow a
PR, eh 4 ¥
COLLEGE FIORD 81
(see fig. 42), but the narrowness of the strait represented
between the island and that portion of the coast said to
2
consist of ice, in-
dicates the impres-
sion of the explorers
that the ice wall
stood not very far
beyond the island;
and this view is
supported by the
Sa statement already
FIG. 42. OUTLINES OF COLUMBIA BAY. quoted that the
A, enlarged from Vancouver’s map (1794), whichdoes jsland was in the
not distinguish the glacier from other parts of the land. ‘“ 9
B, reduced to same scale from plate x1, showing relations northeast corner
of sea, glacier, and land in 1899. O f the bay. I t seems
reasonable to infer that the glacier was not much smaller
in 1794 than in 1899; and that if the features of the em-
bayment prove a recent and important minimum, that
minimum occurred in the nineteenth century.
COLLEGE FIORD
While our boat party was occupied with Columbia
Glacier the main division of the Expedition visited the
northwestern arm of the sound, called Port Wells, where
important contributions were made to geographic knowl-
edge. College Fiord, the right branch of Port Wells, was
explored more thoroughly than ever before, and the left
branch, Harriman Fiord, was discovered as well as ex-
plored. The fiords were mapped by Gannett, and their
beautiful and imposing series of glaciers were photographed
by half a dozen cameras. After the ship had picked up
my party in Columbia Bay, it returned to Harriman Fiord
for Gannett and Muir, and I was thus enabled to sail past
several of the Port Wells glaciers, but the following de-
scription is chiefly at second hand. Many of the best
82 ALASKA GLACIERS
photographs of the Port Wells glaciers are reproduced by
photogravure to illustrate the narrative of the Expedition,
and, to avoid needless repetition, I have selected for my
own use only the views most important in connection with
my text, but I shall refer freely to the plates of volume 1.
College Fiord is from two to three miles broad and
about twenty miles long, trending north-northeast and
south-southwest. Near the south end, where it joins the
main body of Port Wells, there is a bay on the east side
overlooked by two non-tidal glaciers. The larger of these
was called Amherst by the Expedition, the name being
given in honor of an American college. Somewhat north
of the middle the fiord sends an arm to the northeast, and
this arm receives a large tidal glacier, the Yale. At the
head of the main fiord is the Harvard, also a large tidal
glacier. Several branches of the Harvard were visible
from the ship, and that next to the ice front on the north-
west was named Radcliffe. A series of glaciers on the
northwest side of the fiord resembled the Radcliffe in
general character, and four of these received names—
Smith, Bryn Mawr, Vassar, and Wellesley.
Amherst Glacier was passed by the ship at some dis-
tance, and its features are known chiefly through the pho-
tographs secured by Merriam (pl. x1v). It is fed by
névés in full view from the fiord, and approaches the sea
in a short, broad stream which at first descends steeply —
and afterwards more gently. The habit of the lowland
lying between the glacier and the ocean indicates that it
is built of morainic material. Near the sea is a belt of
timber, but this is separated from the ice by a barren tract
similar to that about Davidson Glacier. A barren zone
several hundred yards broad is seen to flank the glacier on
the southwest, and a similar zone borders its companion,
Crescent Glacier. These features doubtless indicate shrink-
age in modern times, the change having been of moderate
x
Oe
a.
¢« .
Vapu fy
+S
_
ee 19
re
.
et ae,
ei
-
EXPLANATION OF PLATE XIV
AMHERST AND CRESCENT GLACIERS
The Amherst Glacier is at the left, in the view, the Crescent at the
right.
These glaciers are on the east side of College Fiord, at its junction
with the main body of Port Wells. Their position is shown in plate
xin. See pages 82-83.
From a photograph made by C. Hart Merriam, June 26, 1899.
Negative No. 124 of the United States Biological Survey.
UMEIOVIH LNSOSHUO UBIOVIDH LSUBHNy
Oa Bzostgs
WVIMYAW AS HdVvVwOOLOHGA
AIX 31W1d ; I IOA “3'WH
eMW. AAPA See
Thre ute %' ani
A
i% ) 1 4
hen Sa ,
é
Ss oak
‘ a3 114
’ )
' 7 os ? e
. ‘ id ia vy i
1 nyt
J
> I
I See Aaee
SOARS ie aMoeeD
y) tii i bi ay aN Sieh ‘ RY)
\F ett We, itis Nene
gee 4 ma wh ’ 4 ‘
aA. } RN 7 ¥
UTA EP aie y
‘hy pe
i
: OR Shue
AM)
bet ¥ By
\ pitt)
: St, ae my
atk 4)
uy} nie
uh ae
MY
’
YALE GLACIER 83
amount, although greater than in the case of La Perouse
and Columbia glaciers. The Crescent is comparatively
narrow, and approaches the sea with a higher grade. A
curve in its trough conceals its upper course.
The Yale drains a larger area and receives a number of
tributaries. The front of the cliff is wide, but of moderate
height, and a blackening, west of the middle, by englacial
drift suggests that a rock knob may lie near the surface,
ready to develop into a nunatak or island if the glacier
shall diminish. The trough in which it lies is forested
along the water edge on both sides for the greater part of
the distance
from the main
fiord to the =
glacier, but SSS * WY AS Soe
* Sf ne - eS é Wa Ss bet A ZA .
barren in the "2" ars
i), i fiZ
Wie rig ZZ
immediate
vicinity of
the glacier.
ahere are
straggling
trees high on
the valley
wall at the
e nd of the FIG. 43. EAST PART OF FRONT OF YALE GLACIER.
° Shows position of front in 1899 in relation to a tributary from the east.
glacier, but ™
they do not come down close to the ice. An excellent
' photograph of the glacier is reproduced at page 128 in
volume i. It is enlarged from negative 113, U.S. Biolog-
ical Survey. A nearer view of the eastern part of the
front (fig. 43), although lacking detail at the critical
point, may serve a purpose for comparison when the gla-
cier shall be revisited. It shows a small tributary, cas-
cading from a hanging valley near the end of the main
glacier.
84 ALASKA GLACIERS
The Harvard Glacier is by far the greatest discharging
to the fiord. Only a few miles of it are visible from the
sea, as the main trunk, traced backwards, curves to the
right and disappears. So far as visible it is of low grade,
its slope being gentler than that of any other we saw ex-
cept the Muir and Columbia; and this feature, taken in
conjunction with the notable height of the cliff in which
it terminates (350 feet), indicates great depth of the ice
stream andaremote source. The large number of medial
moraines tells us that it has many branches, and five are
visible from the sea. One from the southeast joins within
a mile or two of the end, and the other four come from
the northwest and north. All have steep grades in ap-
proaching the main trunk, but two at least show gentler
grades at higher altitudes. The Radcliffe joins the Har-
vard so close to the water front that it does not become
fully merged with the greater stream, but merely coalesces
at one edge on its way to the sea. A conspicuous medial
moraine of the Radcliffe maintains its high declivity quite
to the water’s edge, and the cliff where the Radcliffe
ends is notably lower than the confluent cliff along the
front of the Harvard. The next tributary is likewise
characterized by a strong medial moraine, and the branch-
ing from which this arises can be seen a short distance
back from its junction with the Harvard. The photo-
graphs show no trees in close proximity to the Harvard. .
The point of land at the branch in the fiord five or six
miles to the south is forested, and this forest follows the
coast for some distance toward the glacier, but stops sev-
eral miles from its front. The opposite coast is reported
free from trees at the water’s edge for eight or ten miles,
but at an altitude of several hundred feet the trees ap-
proach the glacier. These relations, while they do not
show whether the glacier is now waxing or waning, indi-
cate that its length has been several miles greater at a
Ww
ie 2)
*}J9| PTUII} Xd 9} 3B ‘AYTOpeA
JY} SIOMIVN B P2ATId9I SBT YIM ou ATMO dy} JIISIA SaTIVINGLI} INoy 94} JO ‘“STQISTA JOU St ‘3Y311 9Y} Je YUBISIP Ivy ‘IdTOvIS 9y} JO peoy oy, ‘“Ssaureioul
[Blpeut ye913 3} Ye YSIy y9J OSE st pu ‘apIM SajIM OA} ULY} DION ST PINS [Vpl} SIT “Jofovl[s oy} Wol sojtw Ussvs pNogsB ‘19}eM JY} WO ST IoAIISqO OL,
“6691 ‘aNof ‘uHIOVIO GUVAUVH ‘bb ‘old
ef oe ny
cea
wR Se
a a
a ASE SS
HARVARD GLACIER
op be,
me
—— “4
=
86 ALASKA GLACIERS
period so recent that the forest has not yet reoccupied the
abandoned ground.
As the Harvard has recently retreated more than its
neighbors, and as its velocity is presumptively high, its
future changes will have special value as indices of the
local variations in the conditions of glaciation, and the
record of its magnitude in 1899 is therefore important.
Unfortunately the party did not approach it closely, and
the photographs are deficient in detail at critical points,
but they will enable the future observer to recognize any
change of important magnitude. The best available data
for 1899 are contained in Curtis’s photograph No. 273,
reproduced at page 72 in volume. The east end of the
frontal cliff, as there shown, is not far (between 1,000 and
2,000 feet) from the apex of a delta, or alluvial fan, built
by the stream from a small hanging glacier. It is also
seen that the eastern part of the glacier cascades about a
half mile from the front, dropping so low that its tidal
cliff has only half the height of that of the central part.
At the west the relation of the Harvard to the Radcliffe
is manifestly sensitive to the influence of advance or re-
treat. A moderate recession would separate the two
glaciers; an advance would deflect the lower part of the
Radcliffe medial moraine into parallelism with the Har-
vard medials (see fig. 44).
Smith Glacier reaches the fiord three or four miles from |
the Radcliffe, and is of the same order of magnitude. Fed
by several tributaries among the crests of the range, it
gathers in a high mountain valley and then descends in
magnificent cascades down the mountain front to the sea.
In the last part of its course it has scarcely any valley,
the outer surface of the ice being practically flush with
the face of the mountain; and there is no flattening of its
profile as it reaches the water. Though its lower slope is
so seamed by crevasses as to exhibit a mere congeries of
87
COLLEGE FIORD
"SId19e[3 97} Jo SAaTTVA JDMOT 91} JO SSOTMOTIENS
24} pus ‘sapeosvo d01 ayT]-dajs aq} ase SaIN}Vdy DSI}OVIVYD ‘plvarey 9y4 Sururof ‘agropeyY ay} usy} pues ‘yIUIS 9y} U9} ‘IaTOBIH IMB UAIG SI 7J2T PT}
IV ‘plonz aZaTOD jo 13}vM 9} Wolst MIAITL “‘WIAX '[d 39g “punog WIBIIIM s0ulIg Jo UOIstAIp eB
‘GUOIA AOATIOON AO ACIS LSAM ‘SH ‘Ora
‘
SITPM Og JO WIB U19q}IOU 9} St PJOI a3aTjoD
———z
88 ALASKA GLACIERS
pinnacles, two lines of medial moraines are distinctly
traceable, each partitioning off a fourth part of the ice
stream at the side.
The Bryn Mawr, next south of the Smith, is somewhat
larger. Its two main branches, gathering in mountain val-
leys not well seen from the sea, become visible in twin
cascades, and then, uniting their streams, make a second
leap to the sea. As tide is reached, there is a tendency to
flatten the profile, and the central portion of the stream
becomes nearly or quite horizontal for a few hundred feet
before breaking off in the terminal cliff.
Next in the series comes the Vassar, parallel to the
Smith and Bryn Mawr and exhibiting a similar series of
cascades, but of smaller size and less direct in its course.
It is cumbered, especially in its lower part, by rock débris,
and close inspection was necessary to determine the fact
that it was actually tidal.
The Wellesley, last of the tidal series, flows with gentle
grade through a mountain trough joining the fiord at right
angles, and then cascades to the sea, into which it plunges
without notable modification of profile. Beyond it are
small glaciers occupying alcoves on the mountain front
but ending far above the water.
The Bryn Mawr, Smith and Radcliffe are represented
in fig. 45, the Bryn Mawr alone in the-frontispiece, and the
Wellesley in a plate at page 122 of volume 1, from a pho-
tograph by Merriam (No. 121, U.S. Biological Survey
series). The Bryn Mawr was photographed at shorter
range by Curtis (No. 276 A), but the view has not been
reproduced.
In the intervals between the tidal glaciers just described
there is no forest at the water’s edge, and the photographs
reveal none at higher altitudes; but a little farther south
the coast is forested, and the trees climb up a few hundred
feet on the moraine heaps under the hanging glaciers.
HARRIMAN FIORD 89
They are separated from the ice, first by a broad belt of
alders, and then by a barren zone. As the spruce forest
in College Fiord nowhere stands close to the ice, but is
separated by a barren zone, it seems fair to assume that
the ice has occupied this zone so recently that the period
since its shrinkage has not sufficed for reforesting; but no
facts are recorded tending to show the nature of the
changes immediately preceding our visit.
The four tidal glaciers on the northwest side of the
fiord, and four branches of the Harvard reaching it from
the same mountain range, show a remarkable agreement
in certain general features of profile. Near their dé-
bouchure they descend in one or more steep cascades
through a vertical space of 1,700 to 3,000 feet, and back
of these cascades their slopes are comparatively gentle.
Their upper valleys are deeply incised, but their lower
valleys are shallow, barely sufficing to hold the ice
streams, so that the faces of the glaciers are nearly flush
with the general face of the fiord wall. These features
indicate that the principal work of ice sculpture was per-
formed when the trunk glacier filled the fiord to a level
somewhat above the line of cascades. It was then that
the fiord wall received its smooth contours, and much of
the general excavation of the fiord may have been per-
formed at the same time. The tributary ice streams from
the side carved shallower troughs, adjusted to their needs,
and were prevented from excavating deeply at any point
because the great trunk glacier gave them a high base-
level of discharge. These tributary troughs will receive
further consideration in the chapter on Pleistocene glacia-
tion.
HARRIMAN FIORD
From the bend where it is joined by College Fiord
Port Wells extends only three or four miles northward
and is reduced in width. Its trough then swings quickly
go ALASKA GLACIERS
to the west and southwest and is continued twelve miles
farther. At the apex of the turn a large glacier (the
Barry) protrudes from the northern shore, reducing the
waterway to a narrow strait. The portion above the
strait, having been discovered by the Harriman Expedi-
tion, was named Harriman Fiord. The general width of
the fiord is from two to three miles. Considered as a
mountain trough, it branches near the middle, but the
western branch is almost wholly occupied by a gla-
cier. Its walls are everywhere high, and it is in fact
a secluded pocket among the mountains. All about
are glaciers, of which four are of large size and six
reach the sea.
Barry Glacier (fig. 46), at the entrance to the fiord,
approaches from the north-northeast. Its low grade indi-
cates a distant
source, but
the source
was not seen,
as its upper
valley was
concealed by
mist. Unfor-
tunately the
map data se-
cured do not
afford an ac-
The glacier comes from behind the dark hill at the right. The
visible tributary descends by two cascades. Doran Strait lies be- curate deter-
tween the glacier front and the sloping point of land at the left. : :
. ati mination of
the dimensions of its end, but it impressed the beholder
as one of the largest ice rivers of Port Wells. Its peculiar
relation to the fiord causes it to be swept by the passing
tide and prevents the accumulation of icebergs about its
front, but the same relation exposes it to exceptionally
rapid melting by the sea, and the conflict of ice current
BARRY GLACIER gI
with tidal current must be active. The forward flow of
the ice tends to narrow the strait, and this constriction, by
increasing the speed of the tide, enhances the melting
power of the water. The fact that the glacier was able
to occupy two-thirds of the width of the fiord indicates
that its forward movement was strong.
=
NN gi
os Mit } f} fiegd
ios Wy ys ot ve ip Ay “i
~ Oh EL
FIG. 47- PART OF FRONT OF BARRY GLACIER.
Showing the relation of a medial moraine toa great oblique dirt band. Photographed by
E. H. Harriman from the ship, June, 1899.
Its moraines were of small relative importance, but
a belt along the western margin was darkened by drift
and there
were two
medials. One
of the latter,
exhibited in
section in _ ric. 48. CAVES IN FRONTAL CLIFF OF BARRY GLACIER.
the face of From a photograph by W. R, Coe.
the cliff, was seen to be the surface outcrop of a sheet
of drift-charged ice which extended obliquely down-
ward, passing under the western portion of the stream
(see fig. 47).
The cliff was further diversified by a number of caves
at the water’s edge, supposed to be the mouths of englacial
streams.
92 ALASKA GLACIERS
Connected with the eastern edge of the ice was a long,
narrow tongue attached to the shore (fig. 49), evidently a
remnant left by the glacier at some very recent date when
its front was more extensive. As this strip was not pro-
tected by gravel, it must have been wasting rapidly, and
the period of its separation may have been only a few
months. I was in doubt whether to ascribe it to a pro-
gressive shrinkage of the glacier or to seasonal variation.
Gi
: ey
GZ
. %
FIG. 49. EAST PART OF FRONT OF BARRY GLACIER.
Showing associated remnant of stagnantice. From a photograph by D. G. Inverarity.
On the same coast the forest did not approach the glacier
closely at the water line, but passed above it, leaving a
barren zone several hundred feet broad. The common
boundary of the barren zone and forest was so well defined
as to indicate that it represented a former limit of the ice,
but there were no overturned trees. If the forest ever
occupied the barren zone, and was there destroyed by an
advance of the glacier, the occurrence was so long ago that
the overturned tree trunks had disappeared through decay.
The portions of the forest nearest the ice included no
trees of large size, but as there were many standing dead
trunks it is probable that the growth was mature and that
the small size of the trees indicated merely conditions un-
SERPENTINE GLACIER 93
favorable to luxuriant growth. Translating these facts into
terms of glacial history, it seems probable that the Barry
had been, at some time within the century, somewhat
larger than when we saw it, but that it had not for a series
of centuries exceeded the limit marked out by the neigh-
boring forest. If any change had occurred within the
last year or two it was of diminution.
The opposite wall of the fiord is forested down to the
water’s edge, and it is thus shown that no recent advance
of the glacier has carried it completely across the channel.
Next west of the Barry is Serpentine Glacier, coming
down to the fiord from the north. It is a broad stream,
of low grade, fed
by four or five
tributaries de-
scending steeply
from amphithea-
_ ters in the encir-
cling mountains.
Though it reaches
the sea, it yields
few bergs, but is
building a mo-
raine barrier
along most of its
front. Its medial
and lateral moraines are conspicuous, especially the north-
ern lateral. Like the Turner and Reid, it seems to rest
on a valley floor considerably above the floor of the
fiord to which it is tributary. Its most westerly branch
(fig. 50) heads in a high valley not fully commanded from
the fiord and falls to the main glacier in two fine cascades.
At the level of the upper cascade, 3,000 to 4,000 feet above
tide, are three hanging glaciers, perched in alcoves of the
valley wall where it curves to join the wall of the fiord.
FIG. 50. SERPENTINE GLACIER.
The main body of glacier lies behind the nearer hill at right.
94 ALASKA GLACIERS
The only observed fact bearing on its recent history
of change is the absence of trees from the valley walls
- near it.
Two of the hanging glaciers are shown, at the left, in
figure 50. The cascading tributary and other branches
of the sien appear at page 124 of volume I, in a
ae : | al iM |
ee i oe so
fst " a y H
‘ ig ass Nd io
CDi BE ne SEO ; =
< ee = , Ss <@ 3 c Ga j y Z Wj
plate repro-
ducing photo-
graph No. 292
of Curtis’s
series.
Surprise
Glacier reach-
a £U
FIG. 51. SURPRISE AND CATARACT GLACIERS. es the fiord
Surprise Glacier (at right) has its source in a valley system be- from the west,
yond Cataract Glacier. and occupies
a deep and long branch valley. Its sources were not
visible, being concealed by the curvature of its valley,
but its moderate grade and the lofty ice cliff in which it
ends, mark it as an important ice river.
Its near neighbor, Cataract Glacier, occupies a narrow
and lofty mountain trough, from the end of which it sends
a steep, tapering tongue down to the sea. It is interme-
diate in type between the hanging glaciers of the Ser-
pentine valley and the cascading glaciers of the west wall
of College Fiord.
The valley containing Harriman Glacier is a continua-
tion of the main trough of the fiord and holds the same
general southwest trend. The glacier curves toward the
west and then toward the south, disappearing from view
at a distance of nearly ten miles. As the most distant
portion seen has a gentle slope and lies far below the
bordering mountains, it is probable that the sources are
still several miles beyond. Its general width is about a
mile and a half, but its high-grade tributaries are so thick-
=e
stony
sively
ditt
tlio to
oft 03 gaignils ttel jasarre1 eeslnoitom 8 yidsdorq et isisaiD neon
Hilo Istnort oct foi" Iti3n99 sel" “to IBgII91 idgile & yd sbie yollay
SOUTH ENG OF FRONTAL CUFF .Oe-pe 20gRq 332
-QQ6r ,TS aint epimoval oO .d yd sbsemt dqsrgotodg s mol
,esttse 2ittu) ari to 08s .o% avitsgo/l
-be bas Rilo latnort oi Yo bro sdizon onl} eworle SAWAA wourol odT
-suom 903 no det Nallay ors jo linw jeswdtron ont to atisg guinio;
70 eeyeq 90¢ «=. 1908! [sme 8 diiw dons ,eyollav gatgand ov o16 miss
Q081, FE nul,
ROR Fo
MhARBRIFN AN tA) =}
1oRn” Eno c FRONTA « “F
EXPLANATION OF PLATE XV
| HARRIMAN GLACIER
The Upper Figure shows the south end of the frontal cliff of the
glacier and adjoining parts of the valley wall. The main part of the
glacier lies outside the view at the right (see plate x1). At the left:
a tributary glacier descends from the mountain, and there are glimpses
of other tributaries farther to the right. The visible part of the Har-
riman Glacier is probably a motionless remnant, left clinging to the
valley side by a slight retreat of the central part of the frontal cliff.
See pages 94—96.
From a photograph made by D. G. Inverarity, June 27, 1899.
Negative No. 286 of the Curtis series.
The Lower Figure shows the north end of the frontal cliff and ad-
joining parts of the northwest wall of the valley. High on the moun-
tain are two hanging valleys, each with a small glacier. See pages 95
and 119.
From a photograph made by D. G. Inverarity, June 27, 1899.
Negative No. 285a of the Curtis series.
H.A.E. VOL.I
= >
I
PLATE XV
HARRIMAN GLACIER
SOUTH END OF FRONTAL. CLIFF
7 a - @- . =a? oo a
™ a * - Sieh oak
-
Sie ea ent Pt te: =~he
PHOTOGRAPHS BY CURTIS
HARRIMAN GLACIER
NORTH END OF FRONTAL CLIFF
t
{
’
he.
DA
.
'
t
‘
an
‘
Bus Hut
y tf LG AD le PY
. K - 4
PS aia Via) bal
MEM TN Rel
' qs ti va i,
4
‘ i
j
y 7
fat :
Ces
5 f
d &
ny)
7 . q
% yy tip
Peary f fal rity )
Welt matt
- bite SSE MeN UT
eee ll Pal
t
‘
‘
v
rae
tha
is
n
IN
‘ <
4
i
h ”
wy
‘
‘A x
Ay
# Fay
oe e* Poy hs
‘ N % i
[2 var Fou
{ c '
é
i A TOS ne
1 ‘ 23 '
.
i
eo
7 wit ay:
{
‘
J
te
:
i
> uw
J
i
i ‘
: \
? 1)
«
‘ ;
oo f
r° ae
j
: *)
2h
4 ‘A i
‘ ;
t
ee ee
i : y
buf -
i
HARRIMAN GLACIER 95
set as practically to coalesce, especially on the south-
east side, giving a broad expanse of nearly continuous
ice and névé. This expanse, fully commanded from
the water, makes the view of the glacier a most im-
pressive spectacle.
The visible moraines are few and unimportant, but the
presence of much embedded drift is suggested by a detrital
bank on which the eastern edge of the ice is seen to rest
at the front. Above this bank the frontal cliff is low and
irregular, but elsewhere it is lofty, ranging in height from
200 to 300 feet. From such a cliff an active discharge
of bergs might be assumed, but our parties encountered
only a moderate quantity of floating ice near the head of
the fiord.
The glacier is not closely approached by forest growth,
but shrubs were seen on the shore of the fiord within a
few hundred yards of the ice. If the ice is diminishing,
the recent retreat of the glacier front would appear not to
have been rapid. The condition of the front in June,
1899, is recorded in a series of photographs. Two of
these, reproduced in plate xv, show the ends of the frontal
cliff, where the ice adjoins the valley walls, and will be
serviceable for future comparisons with reference to ad-
vance or retreat. A third (Curtis negative No. 291),
published in volume I at page 74, gives a distant view of
the glacier and its southeastern tributaries; and a fourth
(Harriman negative No. 98), appearing in volume 1 at
page 262, gives the glacier and its surroundings from a
somewhat nearer point.
Some of the minor glaciers associated with the Harri-
man occupy elevated valleys far above the main trough,
and these upland valleys probably constitute a system
initiated at an earlier epoch, when the fiord was flooded
with ice to a great depth. [Illustrative examples are
afforded by two hanging glaciers overlooking the lower
96 ALASKA GLACIERS
part of the Harriman from the northwest (pl. xv). No
measurements were made, but it is evident from an inspec-
tion of photographs that the heights of such features in
this neighborhood are approximately the same as in the
vicinity of Serpentine and Surprise glaciers, and it is
possible that a number of minor glaciers observed on both
sides of the fiord constitute with these a general system.
Roaring Glacier, between the Cataract and the Harriman,
owes the peculiarity suggesting its name to an abrupt
change of grade. From a comparatively gentle slope it ©
passes to one so steep that loose masses find no lodgment,
and as its movement steadily projects its end beyond the
point of inflection, fragments of ice break away and tumble
down the steep incline, to gather in a heap far below, where
they lie until melted.
The condition of extreme glaciation to which these phe-
nomena point does not belong to the series of modern
changes, and will be referred to again in the chapter on
the Pleistocene history. Were it of comparatively recent
date the fiord would now be destitute of trees, but such is
not the fact. It is true that the slopes are bare in the
immediate vicinity of the glaciers, and that the valley
walls enclosing the greater glaciers—the Barry, Serpen-
tine, Surprise and Harriman— support no trees, but the
lower parts of the fiord walls are elsewhere covered by a
hemlock forest. .
As to the proper interpretation of the peculiarities of
forest distribution the case is not altogether clear. In
other localities there has seemed good reason to ascribe
absence of forest to recent occupation by ice, but here
there is a sort of transition from forest to barren which
suggests climatic limitation. In the zone of transition the
trees are not young and vigorous, as when invading newly-
acquired territory, but scrawny and ill-favored, as though
struggling desperately against the attack of hostile condi-
GREWINGK GLACIER 97
tions. In the accompanying illustration, representing
the edge of the forest nearest to Harriman Glacier,
the rareness a
of branches
on the side
toward the
water sug-
gests that
winter fogs
driven land-
ward over-
whelm the wee :
boughs with EE EE ee
loads of ice. FIG. 52. HEMLOCKS BORDERING HARRIMAN FIORD.
, oe
—
° [Esper tc
GREWINGK GLACIER
West of Prince William Sound we saw glaciers in
abundance —on Kenai and Alaska peninsulas and on
Unimak and Unalaska islands — but only one was visited
or approached so closely as to permit the making of ob-
servations worthy of record.
The Grewingk Glacier is one of a series descending the
northwest slope of the mountainous Kenai Peninsula. It
was mapped by Dall in 1880, and revisited in 1895, when
he made accurate note of the position of the ice front with
reference to an object on the southern wall of the valley.
In 1899 he accompanied me to the edge of the glacier for
the purpose of pointing out this object, and I made a few
photographs and other observations to aid in the recog-
nition of future changes.
The glacier descends with moderate grade from a high
névé, and maintains in its lower part a width of one and
one-third miles. Its front is three miles from the sea, the
interval being occupied by a gravel plain. For half the
98 ALASKA GLACIERS
distance the plain is bounded at the sides by rock walls,
continuous with those containing the glacier, but these
end at the general line of coast, and the plain flares beyond
them as a low, broad cape. It is in fact a delta of glacial
detritus, filling the lower part of the glacier trough and
encroaching on the bay. The building of the plain is
rapid. Its upper part was almost barren, as we saw it,
only supporting enough scattered young spruces to show
that their spread was not absolutely prohibited by soil or
climate. Lower down were plantations of vigorous young
cottonwoods, but no mature groves were seen. Border-
ing lands of earlier origin are covered by spruce forest,
and in places the growing gravel deposit was evidently
invading the forest, overwhelming the undergrowth and
burying the roots of large trees so that they languished
and died. I was impressed with the fact that the quantity
of rock waste discharged by the glacier was much greater
than would normally be discharged by a stream of water
draining a similar area.
The glacier bore no large moraines, and its generous
output of rock waste must have been supplied chiefly by
the englacial drift. The visible belt of this drift was
broad at one or two points, but in general so narrow as to
give the impression that the base of the ice lay consider-
ably below the level of the gravel plain. The ice front
was steep, probably ranging from 20° to 30°, and im-
pressed Dall as much steeper than in 1895. It was de-
cidedly steeper than the front of Hidden Glacier and the
north front of the Hugh Miller, observed a month earlier,
but less steep than non-tidal portions of the Columbia.
If the correlation of high and low frontal slopes with ad-
vance and retreat is well founded, the Columbia and
Grewingk glaciers were advancing in 1899 and the Hid-
den and Hugh Miller were retreating. If the slopes are
related to the direction of the sun, those toward the south
GREWINGK GLACIER
4
eo
Aa
at
t?
aq
——
eS)
net Wats
GREWINGK GLACIER, GENERAL VIEW FROM THE WEST IN 1899.
FIG. 53.
The north edge of the ice (at left) is seen to be separated from the forest by a belt of bare rock. The corresponding feature on the south is shown in figure 54.
\o
\o
I0O ALASKA GLACIERS
are steeper than those toward the north. Close to the ice
front the plain was interrupted by a low ridge of gravel
(see fig. 54), a push-moraine associated with some small
ns fetes.
Pee
bas eae Ne ie ae = " rr
Me. RNR Rag SA
2 § MEER gS + a Ss
&" «. &
FIG. 54. SOUTH WALL OF VALLEY AT FRONT OF GREWINGK GLACIER.
and recent advance of the glacier, and possibly a phenom-
enon of the annual oscillation of the front. Farther out
on the plain the course of a much larger moraine was
marked by a crescentic line of mounds and short ridges,
remnants of a once continuous morainic rampart that had
been breached at many points by streams from the gla-
ciers. I judged that this also was a pushed-up ridge,
resulting from a plowing of the gravel deposit during a
rapid advance of the glacier. It was not strictly parallel
to the ice front in 1899, nor to its outline as mapped in
1880, but was more convex downstream. Its middle
part was 2,600 feet from the glacier in 1899, and its most
southerly remnant 800 feet. In 1880 Dall observed a
considerable amount of ice under the sand and gravel of
these mounds, and I noted many kettle-holes resulting
from recent melting of ice remnants under the gravel
GREWINGK GLACIER IOI
plain inside the crescent. It is therefore probable that the
advance occurred only a few decades ago.
Between 1880 and 1895 the ice retreated through a
space estimated by Dall at 250 feet. Between 1895 and
1899 the portion of the front adjacent to the south wall of
the valley retreated 350 feet. It happened that all of the
observations were made in the same month, so that the re-
corded changes were independent of seasonal fluctuations.
Figure 54, representing the south wall of the valley at
the front of the glacier, shows the position of the ice on
July 21, 1899. The gravel plain and the inner push-mo-
raine occupy the foreground. At the extreme right a low
boss of rock juts from the valley wall into the gravel
plain, and just to the left of it is a large boulder resting on
a drift terrace. On July 29, 1895, Dall found barely space
to pass between the glacier and this boulder.
The same view shows the barren zone of the valley
side and the lower limit of the forest, and the correspond-
ing features for the north side of the glacier are seen
at the left in the general view of the glacier, figure 53.
At the south the line of forest was about 200 feet above
the edge (1899) and descended westward to the gravel
plain in 800 feet. For some distance below the line scat-
tering young spruces and other bushes were seen, and
even within the tract uncovered since 1895 a few alders
had started. Nevertheless, the line of forest was clearly
defined, being the lower limit of mature trees, dead trees,
and accumulated humus. Though the line was unques-
tionably caused by an advance of the ice, it was not
marked by heaps of overturned trees, as at the La Pe-
rouse and Columbia glaciers.
From these various phenomena a number of inferences
may be drawn: (1) For several centuries — the age of the
forest, including its dead trees—the glacier has not ex-
tended beyond the lower limit of the forest; that is, it
102 ALASKA GLACIERS
has not very greatly exceeded its present size. During
that period it may or may not have been much smaller
than now. (2) During the latter part of that period the
glacier advanced to the forest line and then retreated.
This maximum probably occurred as much as fifty years
ago—to allow for the disappearance of the overturned
trees— but could hardly have been so early as the begin-
ning of the nineteenth century, else there would be larger
spruces below the forest line. (3) Several decades ago
there was a maximum, affecting especially the central part
of the glacier, and retreat from this was still in progress
to the close of the century.
There was little difference in the extent of the two
maxima, and although their separateness was not doubted
during my visit, it now seems to me possible that the two
were identical. One was inferred wholly from the fea-
tures of the valley wall, and the other wholly from the
frontal moraine. The straggling of young spruces below
the forest line afforded so strong a contrast to the absolute
barrenness of the morainic mounds that the possibility of
connecting the two groups of phenomena with the same
event did not occur to me; but Dall’s observation of ice
remnants in the moraine in 1880 suggests a local cause
for the sterility of the gravel mounds and leaves the
matter in doubt.
SUMMARY OF MODERN CHANGES
During the last twenty years much attention has been
given to the variations of glaciers, and a large body of
facts has been collected, especially with reference to
European examples. In attempts to generalize these
facts serious difficulties have been encountered, and their
discussion has not yet resulted in a satisfactory theory of
the causes of change. All students of the subject feel the
need of more extended observation, and from the point of
MODERN CHANGES 103
view of the theorist there is special interest in the history
of changes in regions remote from those which have here-
tofore received chief attention. Comparatively little is
known of the history of American glaciers, but the avail-
able data have been carefully collated by Russell’ and
Reid,’ and an important contribution has recently been
made by Klotz.®
The local descriptions of the preceding pages contain
the additional observations made by the Harriman Ex-
pedition, together with inferences as to modern changes;
but as the paragraphs on variations are somewhat scat-
tered, the principal inferences are here assembled in ré-
sumé. The geographic order, from east to west, is re-
tained.
In Glacier Bay the observations pertain to a large area,
containing at the present time a considerable number of
separate trunk glaciers. The data concerning variations
are not equally full in all parts, but so far as comparable
they are harmonious. It is probable that the history of the
whole district centering in the bay is a unit. The history
begins with an epoch when the glaciers were smaller than
now. During this epoch a forest grew to maturity and
then was overwhelmed by gravelly waste from the ice;
the epoch was therefore measured by centuries. The
glaciers then advanced many miles, attaining a maximum
one hundred or one hundred and fifty years ago, and they
have since retreated. Measured to the Muir Glacier, the
total retreat to 1899 was more than fifteen miles; meas-
ured to the Grand Pacific, it was more than thirty-five
1 Climatic Changes indicated by the Glaciers of North America: Am. Geol.,
vol. 1x, pp. 322-336, 1892. Reprinted, with little change, as chapter vim of
Glaciers of North America.
2 Variations of Glaciers: Jour. Geol., vol. 111, pp. 278-288, 1895; vol. v, pp.
378-383, 1897; vol. vi, pp. 473-476, 1898; vol. vir, pp. 217-225, 1899; vol.
VIII, pp. 154-159, 1900; vol. Ix, pp. 250-254, 1901; vol. x, pp. 313-317, 1902.
8 Notes on Glaciers of southeastern Alaska and adjoining territory. By Otto
J. Klotz. Geog. Jour., vol. xIv, pp. 523-534, 1899.
104 ALASKA GLACIERS
miles. The retreat was interrupted by a temporary ad-
vance between 1890 and 1892. |
La Perouse Glacier is practically at maximum now. It
has not been greater for centuries, except that it was a
little longer a few years ago, when it invaded a mature
forest. As its neighbors at the east and west were much
smaller a century ago, analogy suggests that the present
maximum was preceded by an important minimum.
In Disenchantment Bay and its dependencies a great
retreat, amounting to at least five miles along one channel
of outlet and thirty miles along another, has been in prog-
ress for more than a hundred years. There is evidence
of other changes, but their order and dates are unknown.
Columbia Glacier is practically at maximum now, and
was nearly as large in 1794, but an important minimum
probably occurred within the nineteenth century. It has
not been greater than now for centuries, except that it was
a little larger about the year 1892, when it invaded a
mature forest.
The numerous glaciers of Port Wells, including College
and Harriman fiords, may have a harmonious recent his-
tory, but the data are too meager to warrant a definite state-
ment. They are somewhat smaller than at a maximum
which may have occurred fifty to one hundred years ago.
Grewingk Glacier has not for centuries been much
larger than now. It was somewhat larger between fifty —
and one hundred years ago, and may have had a subse-
quent maximum of nearly the same extent.
The most conspicuous fact brought out by the compari-
son of local histories is that they are dissimilar. Never-
theless, there are limited resemblances. The Glacier Bay
and Disenchantment Bay histories agree in including a
great retreat, occupying more than a century. The Port
Wells and Grewingk histories agree in a moderate retreat
occupying something less thanacentury. The La Perouse
MODERN CHANGES 105
and Columbia histories agree in a present condition of
maximum glaciation probably preceded by an important
minimum.
As glaciers grouped together (about Glacier Bay, Dis-
enchantment Bay, etc.) have seemed to vary in harmony,
it is natural to look for a systematic geographic arrange-
ment of the diverse histories; but such arrangement is not
apparent. Port Wells and the Grewingk Glacier, inter-
mediate in type of variation, are the most westerly of the
localities (see nies fig. 55): Between Glacier nie and
Disenchant- f= <== a
ment Bay, rep-
resenting one
extreme of
variation, flow
La Perouse
Glacier and its
neighbors rep-
resenting the
opposite ex-
treme. La
Perouse and
Columbia gla-
ciers, agreeing Sota
in phenomena FIG. 55. DISTRIBUTION OF GLACIER LOCALITIES.
Scale
$9 O S80 100 60 200 250MILES
SS eee ee
of variation, are separated by the contrasted phenomena
of Disenchantment Bay.
Glacier Bay adjoins Lynn Canal, being separated only
by a mountain range, and some of the high névé fields of
this range feed glaciers of both slopes. On both sides the
glaciers are believed to be retreating, but the front of the
Davidson of Lynn Canal is less than half a mile from the
forest on its old moraine, and the Muir of Glacier Bay is
nearly twenty miles from the equivalent forest. The great
Fairweather Range, separating Glacier Bay from the Gulf
106 ALASKA GLACIERS
of Alaska, nourishes many glaciers. Of these the Johns
Hopkins, descending northeastward, has shared the great
retreat of Glacier Bay; but the Brady, flowing south, and
the La Perouse and Crillon and their neighbors, flowing
southwest, have advanced during the same period.
Close to Disenchantment Bay lies the Malaspina, a pied-
mont glacier fed by alpine glaciers of the St. Elias Range.
From other slopes of the same range come the principal
feeders of the Hubbard, the main glacier of Disenchant-
ment Bay. Inacentury or two the Hubbard has retreated
five miles up Disenchantment Bay, but the Malaspina is
bordered in places by a mature forest from which it has
retired only a short distance, and at one point it has even
advanced against the forest within a few years.’
The general fact appears to be that mere proximity
does not ensure parallelism of glacial history; on opposite
sides of a mountain range the sequences of change may
be not only different but antithetic.
THEORIES
In the discussion of the causes of the advance and
retreat of European glaciers the phenomenon occasioning
greatest difficulty is the lack of parallelism between the
variations of different glaciers and different groups of gla-
ciers. The histories of glaciers of the Alps exhibit dis-
parities similar to those of Alaska, with the apparent .
difference that the Alaskan disparities are of larger scale,
just as the Alaskan glaciation has a larger pattern; and
the arctic and boreal glaciers of Europe probably exhibit
equal irregularity, although Rabot, who has recently
assembled the evidence, finds a number of partial corre-
spondences.’
1]. C. Russell. Amer. Geol., vol. rx, p. 329, 1892.
2 Les variations de longueur des glaciers dans les régions artiques et boréales.
Arch. des Sci. Phys. et Nat., 4me periode, vols. 3, 7, 8, 9, Geneva, 1897-1900.
CAUSE OF VARIATIONS 107
For the explanation of irregularity there are two promi-
nent hypotheses. The first, regarding oscillation of long
period as climatic, ascribes minor oscillations to the
rhythmic gorging and disgorging of the névé reservoir.
The rhythmic period, being connected with topographic
conditions, is different in different glaciers.
The second, which has been more fully developed, ap-
_ peals to the principle of lag. The chief cause of variation
of the wasting end of the glacier is believed to reside in
variation of snow accumulation on the névé fields, but con-
siderable time is required for the transmission of the effect
from end to end of the glacier. For average Alpine
glaciers this time is believed to amount to several decades,
but it varies with the length, slope, and other peculiarities
of the individual ice streams, and the general result of its
variation is that ice streams of the same mountain slope,
or streams flowing from the same névé, initiate a period
of advance or retreat in different years or even different
decades.
It is impossible to compare the first hypothesis with the
behavior of Alaska glaciers, on account of the meagerness
of observational data. As yet we know nothing of perio-
dicity of variation. The comparison of the second is ob-
structed by the lack of meteorologic records for the glacier
region, and by the fact that very few of the determinations
of variations are associated with definite dates; no com-
parison with climatic variation is possible, and the com-
parison of individual histories of variation, one with
another, is approximate only. Nevertheless, some judg-
ment may be formed of the general competence of the
second theory; and it seems to me not fully adequate for
the explanation of Alaskan disparities.
Consider, for example, the contrasted histories on oppo-
site sides of Fairweather Range. On the northeast slope
a great advance culminated not less than one hundred
108 ALASKA GLACIERS
years ago, and a great retreat has been in progress ever
since. On the south and southwest slopes the same period
of one hundred years has witnessed a general advance.
The century’s variation for one side of the range, in a
general way and so far as known, is the reverse of the va-
riation for the other side. ‘To apply the principle of lag to
the phenomena it is necessary to suppose that the glaciers
of one slope are very far behind those of the other in some
phase of variation. If the southwestern group are con-
sidered the slower to respond to variations of névé supply,
the inference is that they are now at or near a culmination
corresponding to the culmination of the northeastern
group a century or more ago. If the northeastern group
are considered the slower to respond, the inference is that
though now at very low ebb, they have not yet felt the
impulse which has carried the southwestern group to a
maximum; and many decades, if not a full century, will
be required to bring them to the same phase. It is not
clear to me which horn of the dilemma should be taken, but
in either case the time interval between corresponding
phases is greater than can reasonably be ascribed to lag.
Associated with the theory of lag as applied to the
variations of European glaciers is a generalization that
glacial variation is rhythmic, with a period of about thirty-
five years, each recurrent cycle of variation being brought
about by a corresponding cycle of climatic change. In
this respect also the Alaskan phenomena are discordant.
It is not credible that the great advance and retreat which
occurred in Glacier Bay, involving the extension of glaciers
along the main trough for thirty-five miles, or more, and
their subsequent melting, could be accomplished in so
short a period as thirty-five years; for, though direct ob-
servation has covered but a small part of the great oscil-
lation, it has shown that in the half of thirty-five years the
retreat of the ice front was less than five miles.
CAUSE OF VARIATIONS 10g
Reid has suggested a local subsidence of the land as
a possible explanation of the retreat of the glaciers of
Glacier Bay.’ Stumps of trees that grew in Muir Inlet
before the great advance of the glacier, now stand at low-
tide level, and demonstrate a submergence of at least
twenty feet. The submergence may have been greater;
and he points out that any lowering of the surrounding
land with reference to the sea would make the conditions
less favorable for the accumulation of snow and tend to
reduce glaciers. ‘To extend this explanation so as to
cover the diversity of local histories it would be necessary
to assume that the Fairweather Range was not lowered
in company with the adjacent tract about Glacier Bay;
and it would be logical also to assume that the great ex-
pansion of Glacier Bay ice which preceded its shrinkage
was associated with a rise of the surrounding land. As
there is independent ground for believing that the region
is one of active mountain growth, the occurrence of such
differential and diverse movements is quite conceivable,
and their possibility should be kept in view in the study
of each locality. But as glaciers are highly sensitive to
climatic changes, as climates are subject to continual and
rapid variation, and as earth movements are comparatively
slow and moderate in their influence, the central theory
of glacier variation is necessarily climatic rather than
diastrophic.
With reference to the climatic explanation of the Alaskan
phenomena I have a suggestion to contribute —a sugges-
tion of a somewhat vague character, not yet reduced to
the form of a definite hypothesis. It is, that the combi-
nation of a climatic change of a general character with
local conditions of varied character, may result in local
glacier variations which are not only unequal but op-
posite.
1Nat. Geog. Mag., vol. Iv, p. 40, 1892.
IIo ALASKA GLACIERS
The general drift of the suggestion may be illustrated
by considering some of the more evident consequences of
an assumed change in the temperature of the water of the
Gulf of Alaska. Let us assume that the water becomes
warmer, and that all other factors affecting glaciation
remain unchanged. ‘The consequences would include:
1. A higher temperature for the air currents flowing
from the gulf to the land.
2. A greater contrast in temperature between the coastal
belt and the interior of Alaska, especially in winter.
3. Greater evaporation from the ocean and a higher
humidity for the landward-flowing air — resulting from 1.
4. Greater precipitation on the mountains, especially in
winter — resulting from 2 and 3. :
5. A shorter annual period in which precipitation takes
the form of snow—resulting from 1.
6. A (probably) lower ratio of snow to rain — resulting
from 5, qualified by 4.
7. A higher snow-line.
8. More rapid waste of ice and snow by evaporation
and melting —resulting from 1, 5 and 7.
Of these consequences, the increase of precipitation
would tend to enlarge glaciers, while the lessened ratio of
snow precipitation and the enhanced wasting would tend
to reduce them.
Evidently a lowering of the temperature of the gulf
water would be followed by the reverse consequences.
If the hypothetic rise of ocean temperature were carried
to an extreme, the snow-line would be driven above the
mountain tops and the glaciers would disappear. If the
hypothetic fall of ocean temperature were carried to an
extreme, so as to abolish the contrast between sea and
land temperatures, the southern coast of Alaska would be
reduced to the condition of the western coast, and glaciers
would disappear from all but the highest mountains.
CAUSE OF VARIATIONS II!
There is, therefore, a temperature of ocean water which
is more favorable for the development of glaciers in the
coastal mountains than a higher or lower temperature.
But this temperature is not the same for all parts of the
coastal belt; it must vary with local topographic charac-
ters. The glaciers of a low range may be more sensitive
to variations of the snow-line than those of a high
range. Glaciers facing the sea may be more sensitive
to the variations of wastage dependent on the tempera-
ture of the incoming winds than are glaciers facing the in-
terior. Glaciers fed from cirques, where snow is concen-
trated by wind and avalanche, may respond to variations
of precipitation in a very different way from glaciers fed
by open névé fields, where much of the annual snowfall is
dissipated by dry evaporation. The laws of variation for
high-grade glaciers may be quite different from those for
glaciers of gentle slope. And so, when the ocean tem-
perature approximates the value most favorable for the
development of glaciers in the district as a whole, it will
be too warm for the highest development of certain gla-
ciers and glacier systems and too cool for others. And
whenever such a condition obtains, a change in ocean
temperature will cause some glaciers to enlarge and
others to contract.
It is of course impossible that one of the meteorologic
conditions determining Alaskan glaciation should vary by
itself while all other conditions remain constant, and the
case assumed for the sake of illustration is therefore
purely ideal. It has served its purpose if it has given
plausibility to the suggestion that a change in some
meteorologic factor or factors may result in simultaneous
modifications of glaciers which differ not only in amount
but in algebraic sign.
Whatever may be the causes of the variations of gla-
ciers, Alaska affords an inviting field for their investiga-
I1Iz2 ALASKA GLACIERS
tion. Intermediate in accessibility between the glacial
districts of Europe and Greenland, it is more comprehen-
sive than either in variety of local circumstance. The
complexity of interacting conditions may for a long time
baffle attempts at analysis, but when the complexity has
been resolved, the resulting theory should have wider
application than one founded on simpler phenomena.
WR COHOOCEC( EEL CCT EEL COLE RE CEE ECOL CE CECE CE COCO COOL TE CEE OL Ee
:= —— ———— a ee a ———— —_
BECOME Ae
‘ F
{|
ae |
At
.eee. DRoPP RRL reTee
Peete Cees Clas | acandd
‘ |
|
x2 ll
et
DSS ;
pee
——
Peer
ERR,
JLVIPP SPDT PR rE Teer ar
“. oe) | ore
. ° =
HFIP y>yDEVTHDAYYPDTANDDDDYNAYONLAG RODDED DD DNBD) PRD DLDPSDSVDDYDD VEYA DODSO DS DYNNDD BADE BACUDORSDY RPPAB ID
ee ——
S ce 8" —
#2 vvL dS VERT PEPE RFDATPIRIATI SS VNFAYLY DSP EEL DrPEPEDD) PREdISIE DVT F SDP ATEP LOUIE TW Ey DES EOEDY WeOel bY ERY ER LEST SRE EP SERED eh ESSER AFT E DEED SPEDE ED ET
rat
CHAPTER II
PLEISTOCENE GLACIATION
ALL geologists who have studied the region we tra-
versed are agreed that the glaciers were much more ex-
tensive in Pleistocene time than now; but opinions dif-
fer widely as to the actual magnitude of the ancient ice
fields, and also as to the extent to which they modified the
topography of the country. As the nature of my journey
rendered my view somewhat cursory and superficial, and
as nearly all parts of my route had been covered, with
better opportunity, by one or more of my predecessors,
I can not expect to settle any of the vexed questions, but
it still seems best to make rather full record of my obser-
vations and impressions. When an observer views a
complex phenomenon his attention is naturally directed
to the particular features which his previous training en-
ables him to appreciate — he “sees what he has eyes to
see”; and the difference of eyes makes the work of
independently trained observers. more or less comple-
mentary.
( 113 )
114 ALASKA GLACIERS
HANGING VALLEYS
Of the various classes of evidence from which the his-
tory of Pleistocene glaciation is inferred, the physiographic
is most available to observers who see the land chiefly from
the deck of a vessel. Ice-scoured surfaces referable to
the ancient glaciers were occasionally discovered during
our journey, and a few drift deposits were closely exam-
ined; but such observations served chiefly as checks on
inferences from topographic form.
The general characters of the physiographic data which
may be used in such studies are familiar and need not be
recited here, but a special sculpture feature — the hanging
valley — may need introduction to some of my readers.
Its utility in the interpretation, discrimination and estima-
tion of the work of Pleistocene glaciers has been little
appreciated until quite recently,’ but in the study of the
Alaska field it was found extremely useful.
A hanging valley is a small U-valley tributary to a
larger valley, the floor of the smaller being considerably
higher at the junction than the floor of the larger. Many
of them are short, high-grade troughs, heading in cirques;
some are mere cirques, without troughs — spoon-bowl hol-
lows, high on the walls of main valleys. They are asso-
ciated with other evidences of glacial sculpture, and the
_elevation of their floors is believed to result, as a rule,
1 Lake Chelan, by Henry Gannett: Nat. Geog. Mag., vol. rx, pp. 417-428, 1897.
Glacial erosion in the valley of the Ticino, by W. M. Davis: Appalachia, vol.
IX, pp. 136-156, 1900. Glacial erosion in France, Switzerland and Norway, by
W. M. Davis: Proc. Boston Soc. Nat. Hist., vol. xxix, pp. 273-322, 1900.
Review of the last by T. C. Chamberlin: Jour. Geol., vol. vin, pp. 568-573,
1900.
Davis’s second paper reviews the literature, points out that McGee, De Lap-
parent and Richter had advanced somewhat similar ideas as to the origin of
hanging valleys before the appearance of Gannett’s paper, and mentions an
unpublished address by Penck. The glacial explanation of the hanging valleys
of the Alps is opposed by Bonney and Garwood in Quart. Jour. Geol. Soc.
London, vol. Lviu, pp. 690-718, 1902.
HANGING VALLEYS II5
from the unequal erosion of valleys by glaciers of un-
equal size.
Where a trunk glacier of alpine type receives a rela-
tively small lateral tributary the main ice stream gives
base-level to the tributary. Their relation in this respect
is homologous with the relation of main and tributary
streams of water. If the magnitude of trunk and tribu-
tary have remained constant long enough for erosion to
bring about an adjustment of grades, the surface of the
tributary at the point of junction has the same level as the
adjacent surface of the trunk. But the bottoms of the
two channels do not have the same level. The trunk
stream is normally deeper than the tributary, and at their
junction its bottom lies at
a lower level. If the
streams (of ice or water)
be removed, the bottom of
the tributary channel is
found to end high up on
the side of the main
channel.
The ideal case, diagram-
matically illustrated in
figures 56 and 57, is also il-
lustrated in the actual topo-
graphy of couaaaes § regions FIGS. 56 AND 57. DIAGRAMS ILLUSTRA-
sculptured by Pleistocene TING ORIGIN OF HANGING VALLEYS.
laciers 56. A terrestrial block containing a trunk
& ‘ glacier and tributary with well adjusted chan-
The hanging valley is es- els.
r - ? < 57. The same block without the ice, show-
pecially significant in two _ ing the adjusted glacier channels, The trunk
li f h ° hi ° channel is deeper than the tributary; the trib-
ines Of physiograpNic 1M gtary channel isa hanging valley on the side
terpretation. It is-a con- ‘he ‘unk channel.
spicuous earmark of the former presence of glaciers; and
it helps to a conception of the magnitude of Pleistocene
glacial erosion.
116 ALASKA GLACIERS
Its value as an earmark depends on the principle of
exclusion; glaciation is the only physiographic process
known to produce such forms. It is true that discordance
of level between trunk and tributary valleys is not by itself —
diagnostic of glaciation, for it often occurs as a temporary
condition in systems of stream-made valleys, especially
when fresh uplift stimulates down-cutting by -trunk
streams; but in such cases discordance is associated with
the narrow trenches of youthful or rejuvenated topog-
raphy. It is true also that the glacial U-trough is some-
times (though rarely) simulated by products of stream
erosion, and that a hollow closely resembling the glacial
cirque is occasionally produced by aqueous process; but
these imitative forms belong to the middle life of a stream,
when down-cutting has so slackened as to permit valleys
to broaden, and they imply a harmonious grading of stream
beds, inconsistent with discordance of level at the junc-
tion of tributary and trunk. But the combination of dis-
cordance of level with U-shaped cross-profiles constitutes
a physiographic type peculiar to the work of glaciers.
The significance of the hanging valley for the valuation
of glacial erosion depends largely on the assumption that
», the discordance of level was
mae po produced by the glacial exca-
Soe vation of the main trough, and
3 this assumption requires qual-
| ification. If ABC in the dia-
FIG. 58, DIAGRAM ILLUSTRATING gram (fig. 58) be the cross-
DISCORDANCE OF HANGINGVALLEYS. profile of a main glacial trough,
DE the longitudinal profile of a tributary trough, and EF
the produced floor of the tributary, the ‘discordance’ is rep-
resented by the height of / above #. If the preglacial
stream valleys were accordant in grade, their junction
was at /, or some point above /; and FB is the meas-
ure either of the deepening of the main trough by the
0) PRS
~
y
ead Wa TT
y A a y «
% iM i Paes o
me
4
1714
‘es walue as an earmark is on Rhe principle of ¢
exclusion; glaciation is the only. 1D ee * tic ro ess
known to produce such forms. itis ty i pdliscordance
‘of level between trunk and tributary oe at by itse
diagnostic of glaciation, for it often | fe .
condition im systems of sreameamade 7
when fresh uplift stimulates © et
streams; but.in such cases discordenay Weis
the narrow trenches of youthful. or rep an ated topo
raphy. It is true also that the glacial U-trough is some- ~
times (though rarely) simulated by products. ete ream
erosion, and that a hollow closely renee hy: ried acial
cirque is occasionally produced by aqueous f 58 3 mut 3
these imitative «forms belong t the middle ico a ream,
vy) oe
ie! a
ae age” ee
~— rtm,
ficaGiort. + If aBCw ae | “ie ot |
FIG. §8. canst iE: grasa. (6g 58) be the Sat
DISCORDANCE OF MANGINGOVALLEYS. profite of a main glacial tr rough, eo
DE the longitudinal profile of a tributary trough, an ¥ E, aie :
the produced feor of the tributary, the ‘discordance’ is rep> -
resented by the height of # above #. If the preiheail 4
stream valleys’ witre accordant in gradé, their junction —
sat &, or some point above 7; and #P is the meas=
a eithe: of the deepening of- the main yee by the
H.A.E. VOLLIII PLATE XVI
eo
|
A "HANGING VALLEY, FRASER REACH.
HANGING VALLEYS 117
glacier, or of the difference between that deepening and
the deepening of the tributary. If the preglacial val-
leys were discordant, the main valley must have been
young, and was probably so narrow that its conversion
into a U-trough involved much excavation at the sides.
In either case, therefore, the occurrence of high hanging
valleys is indicative of great erosion by ice.
Yet another qualification is necessary, for there is a
special condition under which a relatively young stream
valley may have the width of a glacial U-valley. When
the activity of streams is revived by uplift, the general
degradation may be outstripped not only by trunk streams
but by strike streams following outcrops of weak rocks;
and if the contrasts of rock resistance are great, a broad
belt of weak rock may induce the development of an open
valley or wide trough, while neighboring uplands of re-
sistant rock are still little modified. ‘Thus may arise a
topographic condition susceptible of conversion by only a
moderate amount of subsequent ice work into a typical
glacier trough with hanging valleys.
Theoretically, then, there are at least three cases to be
borne in mind in inferring the quantity of glacial erosion
from the existence of hanging valleys. First, the grades
of preglacial streams may have been accordant, in which
case the discordance of hanging valleys with trunk valleys
yields a rough measure of the depth and amount of glacial
erosion. Second, the grades of preglacial streams may
have been discordant, and without dominant control of
contrasted rock texture, in which case the erosive work
of ice may have consisted chiefly in the enlargement of
V-gorges to U-troughs. Third, the discordance of pre-
glacial grades may have been associated with the rapid
opening of valleys in weak rocks, in which case the erosive
work of ice may have been small. The criteria for dis-
criminating the three cases have not been worked out,
118 ALASKA GLACIERS
but a few general propositions may be advanced. In the
first case a study of the district should discover independ-
ent evidence of the maturity of the preglacial topography.
In the second and third there should be independent evi-
dence of rejuvenation of preglacial streams. The third
could not arise unless the main troughs follow the strike.
The practical problem is further complicated by the fact
that the type of initial topography, when determined, leads
to only a limiting value for the total erosion, and also by
the complexity of glacial history as dependent on climatic
variation. A glacier which begins erosive work by
broadening and rounding the cross-profile of a stream
gorge does not cease activity when that result is attained.
One which falls heir to a weak-rock strike valley, fairly
adjusted to its conditions of flow, may carry the work of
excavation far beyond the grade limit of the ancestral
stream, and hollow out a lake basin or fiord trough. And
the coordinated system of grades and channel forms toward
which the erosive work of grouped glaciers tends, is itself
modified by every change of the general volume of ice.
But despite all qualifications the hanging valley is the
most important witness yet discovered to the magnitude
of the work accomplished by the alpine glaciers of the
Pleistocene.
The hanging valleys of Alaska are illustrated by many of
the figures and plates of this volume. The mouth of one
overlooking Hidden Glacier is imperfectly shown in plate
v and figure 28, and an alpine valley truncated below by
erosive action of the glacier appears in plate vi. Figure
30 shows the mouth of a hanging valley above Nunatak
Fiord; a glacier issuing from a hanging valley north of
Nunatak Glacier is shown in figure 31; and a glacier cas-
cading from a hanging valley of the south side of the
same trough in figure 32. Figure 43 shows a tributary to
Yale Glacier issuing from a hanging valley, and figures 44
INLAND PASSAGES 1 fe)
and 45 a series of similar valleys and glaciers bordering
College Fiord and Harvard Glacier. In figure 46 two
hanging valleys are shown, the one empty, the other fur-
nishing a tributary to Barry Glacier; in figure 50 are two
high valleys with small glaciers overhanging Serpentine
Glacier; and figure 51 represents Cataract Glacier, issuing
from a high valley and cascading to Harriman Fiord. All .
these examples, occurring in the preceding portion of this
report, are incidentally included in views selected to illus-
trate other features. In the following portion are a num-
ber of views chosen wholly or partly with reference to
hanging valleys; and the remark applies especially to plate
xvi and to figures 62, 66, 69, 70, 71, 72, 74, 76, 77, 81, 88
and 93.
THE DISTRICT OF INLAND PASSAGES
From Puget Sound, Washington, at the south, to Lynn
Canal and Glacier Bay, Alaska, at the north, a space of
goo miles, the coast of North America has a peculiar and
significant facies. It is divided into a fringe of rugged
peninsulas by deep, narrow inlets, and guarded from the
surges of the open ocean by a great number of rocky
islands and islets. In this respect it resembles the coast
of Maine and the western coast of the Scandinavian pen-
insula, and, like them, its peculiar characters are associ-
ated with evidences of extensive glaciation. It differs
from those coasts in the fact that some of its islands are
of great extent, so as to include or be constituted by
mountain ranges, and in this respect it is paralleled by a
single district only, the western coast of the southern ex-
tremity of South America.
The map of the district, figure 59, though drawn to so
small a scale as to show only the larger islands and prin-
cipal fiords, serves to illustrate the intricate penetration of
the land by the sea. It is reduced from the large chart
(3689) of the U. S. Coast Survey.
120 ALASKA GLACIERS
MAP
OF PART OF
\ THE WESTERN COAST
‘ or
| NORTH AMERICA
: 8 HOWING
ISLANDS.AND FIORDS
‘ Scale
o 80 100 iL En
sae ee “Be in ia)
% A :
Bo
FIG. 59. FIORDS OF THE INLAND PASSAGE DISTRICT.
INLAND PASSAGES I2I
The general trend of the coast of the mainland is north-
west to north-northwest, and this trend is shared by the
longer axes of the principal islands. There are thirty-two
islands exceeding twenty miles in their greater dimensions,
the maps show more than 400 islands above one mile in
extent, and the islets are uncounted.
With minor exception, the peninsulas and islands are
mountainous, descending steeply to the water, and the
passages between them are deep. Most of the inlets of
the mainland
and many of
the passages
dividing islands
are of approxi-
mately uniform
width for long
distances, and
the parallel
shores of such
linear water- 16-60. AN ALASKA FIORD; TRACY ARM, HOLKHAM BAY.
ways are usually steep and somewhat simple in contour.
Repeating thus the characteristic features of the Norwe-
gian coast, they fall within the physiographic class to which
the name fiord is applied. The northwesterly trend char-
acteristic of the islands affects also the passages between
them, and has enabled navigation to select for its use a route
close to the mainland, where deep waters are almost wholly
protected by the islands from waves and storms of the open
ocean. This route is commonly known as the‘ inside pas-
sage.’ Our steamer followed it on both the outward and
return voyages, our principal deviation from it being
made by a visit to Sitka, which lies on the southwest or
oceanic side of Baranof, one of the outer line of islands.
Parts of the journey were made at night, but the outward
and inward courses, taken together, showed us much the
I22 ALASKA GLACIERS
greater part of the inside passage, and our examinations
about Sitka occupied several days. An excursion to
White Pass gave a view of a canyon at the head of a
fiord, and of uplands at 2,000 to 2,500 feet altitude, but
the higher summits were seen only from stations at~-or
near sea-level.
Direct observation of the uplands was afterward supple-
mented by the study of photographs. The U. S. Coast
and Geodetic Survey and the Canadian International
Boundary Commission have used the camera freely in con-
nection with topographic surveying, and I was so fortu-
nate as to have access to their series of pictures. The latter
organization spread a web of triangulation over all the
mainland portion of southeastern Alaska, and from each
of the mountain peaks occupied as stations photographed
the entire horizon, using the views afterward for the con-
struction of contour maps. Their album thus represents
the upland in a systematic and thorough way and is emi-
nently adapted to physiographic study. (See page 6.)
In this, as in other districts of Pleistocene glaciation, it
is evident that the Pleistocene sculpture is superposed on
an earlier sculpture, chiefly aqueous; and in the discus-
sion of the work of Pleistocene glaciers it is necessary to
consider the pre-Pleistocene condition. I find it conve-
nient to begin with that consideration.
Pre-Pleistocene Topography
So far as we saw the indurated rocks, and so far as we
know them from the descriptions of others, they are either
igneous or metamorphic. The igneous rocks are almost
wholly intrusive. The metamorphic exhibit various de-
grees of alteration, but all are so folded or squeezed that
the planes of structure make large angles with the hori-
zon. ‘The general strike is believed to be parallel to the
coast, but there are few direct observations of strike. In-
HIGH PENEPLAIN 123
ference rests partly on the trends of structure lines deter-
mined by the Canadian Geological Survey in neighboring
parts of the continent, partly on the trends of the straighter
valleys and channels of the region itself.
From this complex the pre-Pleistocene topography was
developed by erosion. The only constructional forms we
saw which might have antedated the Ice Age were a few
volcanic cones. The system of relief was related to three
known base-levels. The plane of the first is now high in
air, above some of the mountains and among the peaks of
others. The second is not far from present sea-level, and
the third is below sea-level.
The fligh Peneplain.— 'The uplands of the mainland
are remarkably uniform in general height over large areas,
not indeed presenting plain surfaces, but either exhibiting
harmony of crest lines, despite profound and general dis-
section, or else occupied by numerous small shallow val-
leys, which are strongly contrasted with the deep steep-
walled trenches of a less complete dissection. These
features can be most readily presented in connection with
some of the accompanying illustrations. Figures 3, 61,
62, 63, 75, and 77 were drawn from photographs by the
Canadian Boundary Commission.
Figure 61 shows the upland topography north of the
western end of Cross Sound. (The reader can identify
the locality on the map, page 120, as the third cape west
of the mouth of Glacier Bay.) We stand on a summit
above Cape Spencer, and look northwest. At the left is
the Pacific Ocean; in the center distance, the end of
Fairweather Range (the nearest high peak being La Pe-
rouse, 10,750 feet); at the right, Brady Glacier, its foot
separated from Taylor Bay by a gravel strand. Between
us and the base of the mountains, 18 miles away, are a
series of hills somewhat uniform in height. The higher
points (as we learn from the Commission’s contour map)
‘
124 ALASKA GLACIERS
range from 2,000 to 2,500 feet above tide, and near the
mountain rise above 3,000 feet.
Viewing these hills collectively, one can hardly fail to
be impressed with the appearance of system in their
crest lines. Some of the hills have broad and flattish, or
gently arched, backs; and all the higher parts of their
profiles seem to belong to a single gently sloping plane.
~Should the valleys between them be filled up even with
the crest lines, the group would become a plateau with
undulating surface. It is natural for the geologist, when
he sees such a harmonious arrangement of hill tops, to
seek an explanation in the structure of the rocks, but in
this case a structural explanation can not be found. The
rock layers are not horizontal but nearly vertical, and
they have been cut across in the shaping of the land.
The local elements of the upland forms are due purely to
erosion. The most probable explanation of the phenom-
ena is that the area was first worn down to a plain at or
near sea-level, afterward raised so as to be a plateau, and
then dissected into a group of hills. The habit of the
hills indicates that the principal work of dissection was
by streams, but there was also glacial sculpture. They
were overrun by the ice-sheet, and the glacial rounding
of summit angles helped to obscure, though it failed to
destroy, the evidence of the old base-level plain.
Yet other evidence of the geologic history is connected
with the trends. The rock structure strikes northwest,
or from the foreground toward the mountains, and this is
also the trend of the upland as a whole. But the crests
of individual hills trend east of north, making angles of
50° to 60° with the strike; and the separating valleys
have the same trend. The valleys do not head against
high summits among the hills, but traverse the plateau
from side to side. They seem to be the work of a system
of streams whose courses across the plateau were deter-
HIGH PENEPLAIN
UPLAND TOPOGRAPHY NEAR CAPE SPENCER.
FIG. 61.
A chain of hills carved from an original plateau. See page 123.
125
mined by some
cause other than
the rock struc-
ture. As their
direction coin-
cides with that
of the local in-
clination of the
old peneplain, it
is highly proba-
ble that they
were super-
posed on the
rock structure at
the time of the
uplifting of the
plateau. The
great valley
holding Brady
Glacier and Tay-
lor Bay, on the
other hand, runs
parallel to the
strike of rocks
exposed in the
hills, and may
fairly be as-
sumed to occupy
the outcrop of a
belt of compara-
tively weak
rocks.
If now we
project the sum-
mit plane of the
126 ALASKA GLACIERS
hills backward across the Brady-Taylor valley, we find
that it passes among the highest peaks of another and
higher upland, an upland lacking the broad summits of the
Cape Spencer hills, but characterized instead by notable
uniformity in the height of numerous acute summits. A
suggestion of this character may be seen at the right
in figure 61.
Before leaving this view, note should be made of the
fact that the peneplain of the Cape Spencer hills ends
northward at the base of Fairweather Range. The range
is distinct in physiographic type and in geologic history.
The reader is now asked to turn back to figure 3, drawn
to give a bird’s-eye view of Davidson Glacier, but show-
ing also the east wall of Lynn Canal. The point of view
is not quite so high as the crest of the opposite wall, but is
high enough to show that the upland bounded by that wall
has plateau characters. There are none of the smooth
crest lines seen in figure 61, but angular peaks and crests
standing close to the mural face combine with angular
peaks and crests farther back to give an even sky-line.
All the valleys visible are upland valleys, and it is not
hard to believe that these have been carved out of an
uplifted block, the plane of whose original flat top runs
among or above the phalanx of sharp summits.
This upland stands about 3,000 feet higher than the
hills of Cape Spencer, and is eighty miles northeast of
them. ‘The intervening uplands are parted by two great
fiords, Lynn Canal and Glacier Bay, and are considerably
dissected in detail, but where most massive they have the
plateau habit shown in figure 3; and they are intermediate
in height between the plateaus at east and west.
In figure 62 we have the view commanded from a peak
like one of those against the sky in figure 3. The locality
is twenty-five miles farther south, and we are looking
eastward from a point about five miles east of Lynn Canal.
HIGH PENEPLAIN 127
The higher summits have a general altitude of 5,200 feet.
It is now evident that the sculpture is that characteristic
of the work of local glaciers. The sharp peaks overlook
cirques, many of them still filled with ice; below the
cirques are short glacier troughs; and between the troughs
are narrow crests. These glacier troughs are not insig-
nificant features—the beds of those in the field of view lie
1,000 to 2,500 feet below the plane of the high peaks —
but they are so small in comparison with the great earth
block from which they have been hewn that they do not
prevent the imagination from restoring its original outlines.
4, 44
0)
je fy
Ly Jif. Za
if,
/
kg
oy MG ,
Wf fl! “Wy i /
a) | Ws
i ah Mpa f ie
FIG. 62. UPLAND TOPOGRAPHY NEAR BERNER BAY.
A deep long glacier trough traverses the view from dis-
tance to foreground. It is occupied in part by a glacier,
in part by a filling of glacial waste; and its rock bed is
far below sea-level. It is related to the fiords and must
be considered in another connection. In the present con-
nection it need be thought of only as a trench dividing
the upland, and helping, through contrast, to exhibit the
upland’s plateau character.
Other illustrations of the plateau dissected by Lynn
Canal and its branches are to be seen in figures 75 and
128 ALASKA GLACIERS
77. In each case the point of view is so low that the up-
land peaks do not unite in an even sky-line, but other
plateau features are brought out.
The correlation of the Cape Spencer peneplain with the
Lynn Canal plateaus brings together very different topo-
graphic types, but they are not essentially incongruous.
The greater height of the inland district has caused it to
be occupied by local glaciers, which have scooped out a
system of cirques and rounded valleys, leaving the inter-
vening crests angular. The cape district is and has been
too low to initiate glaciers, but has been overflowed by
Uh, f ht
2 tle Y
he > = SS hy AN Rath, UC SSNs : Wein.
Poe a eae 5 c? AS Wh mS SS poares el
Se LLG ser 2 a
cha, La ae aad \ Zs, Lae seine
a ieee
ee ta —— =P 2 ae ae) ee
eed mS ¥) ayy Sonny — = pe, ia SS a
FIG. 63. UPLAND TOPOGRAPHY NEAR WALKER BAY, BEHM CANAL.
an ice-sheet originating outside it. It therefore lacks
cirques and the sharp crests developed by cirque erosion,
but has suffered a somewhat equable reduction of its flat-
tish summits.
In turning attention now to figure 63, we leave the
region of Lynn Canal and pass three hundred miles south-
ward to the Walker Bay region near Behm Canal. The
general height of crests is here 4,000 feet. The even sky-
line includes a few sharp peaks, suggesting the cirque
sculpture of the northern area, but most of the distant
summits and all of the nearer are rounded, as by an over-
HIGH PENEPLAIN 129
riding ice-sheet. The deep dissection indicates a subse-
quent history different from that at the north, but the
evidence of an initial peneplain is at least equally clear.
The approximation of the summit heights to uniformity is
too close to be accounted for without the hypothesis of an
uplifted plain; but the departures from uniformity indicate
that little if any of the original plain survives.
The general interpretation of these upland features ap-
pears to be as follows: After the folding and squeezing
of the metamorphic rocks, there was a long period of
erosion, in which broad tracts of the land were worn
down nearly to sea-level. Then came uplift, producing
a plateau from 3,000 to 6,000 feet high, and erosion has
followed. In some places, at least, this plateau sloped
gently toward the sea, and its plane may have remained
everywhere continuous, diversified only by moderate
flexures; but there is also possibility that it was inter-
rupted here and there by faults. The period of subsequent
erosion has been long enough for the development of local
peneplains at a lower level, and in that time the plateau
has been greatly modified. Not only has it been dis-
sected by the eating out of gorges and valleys, but its
back has been worn and fretted, largely by local glaciers,
until all the original surface and much of the original form
have disappeared. What remains is chiefly a tendency
to uniformity of crest height in the ridges and peaks of
certain districts.
It is probably true also that vestiges of the high pene-
plain are conspicuous only where the rocks are com-
paratively durable. Our best examples are along the
mainland east of the archipelago, and that region, accord-
ing to Dawson, is largely granitic. The dominant rocks
of the archipelago are metamorphic, and we saw little
from the ship’s deck to suggest that the uplands of the
islands have a plateau habit. The mountains next the
130 ALASKA GLACIERS
water do not in general rise very nearly to the plateau
plane, and we were frequently able to see that those
farther back are higher. Even where the channels
between islands are most sharply incised it is probable
that they are excavated in the bottoms of broader hollows.
My general conception of the configuration at the date
of the lower peneplain—a conception necessarily vague,
as well as provisional — is that it included all phases of
the topographic cycle, being infantile to adolescent where
the rocks are most resistant, adolescent to mature in the
greater part of the Alexander Archipelago, and senile
where the rocks are weakest. In the granites were nar-
row gorges, set far apart, and reduced to low grade only
where draining large tracts. Between them were tabular
uplands with mild relief, except for occasional unreduced
peaks, or monadnocks. In the stronger metamorphics a
system of graded waterways divided the upland into
mountain ridges, with scattered remnants of the summit
plain. The master streams were largely consequent to
the seaward slope of the old plain, but were in part
diverted to lines of strike; and minor streams were ad-
justed to rock structure.
Low Peneplains.—Along the passages and channels
we traversed, bold coasts are the rule and forelands of
any character the rare exception, but at two localities we
saw unmistakable traces of a peneplain between mountain
base and the descent to deep water, and in the light of
their evidence it seemed proper to give a similar interpre-
tation to various features of obscurer character.
Annette and Gravina islands lie next to the mainland
in the southern part of the Alexander Archipelago. Out-
side them on the west is the great Prince of Wales Island,
from which they are separated by a broad channel, 1,500
to 1,700 feet deep. Each island contains a mountain mass
bordered on the west by a low foreland, the foreland being
LOW PENEPLAINS ee
related to the mountain as peneplain to monadnock. On
Annette Island, where we landed, the foreland is not
continuous, being divided by a bay, but its parts, together
with several low islands, appear to be remnants of a more
extensive plain. The rock is slate and mica schist, and
_ that of the adjacent portion of the mountain quartzite. In
detail the surface is somewhat uneven, low moutonnée
bosses alternating with hollows that hold pools and
bogs, but there is a general and gradual ascent from the
sea front to the mountain base, where the altitude may be
three or four hundred feet. Figure 64 presents one rem-
FIG. 64. PART OF ANNETTE ISLAND.
Showing relation of foreland (peneplain) to mountain, as seen from New Metlakatla.
nant of foreland in profile, as seen from the other, and in-
cludes also rocky islets.
As this whole region was deeply buried by Pleistocene
ice, the unevenness of the foreland is readily understood
as the result of glacial erosion subsequent to the original
planation. Probably none of the original surface remains,
but the glacial degradation must have been locally quite
moderate, or the general plain character would not have
survived. The phenomena do not yield a close determi-
nation of the pre-glacial relation of sea-level to land, but
it could not have differed greatly from the present.
The second locality is Sitka Sound, 175 miles to the
northwest, and on the ocean front of the archipelago.
Back of Sitka the mountains of Baranof Island rise
abruptly to a height of several thousand feet, and they
are penetrated by inlets and lake valleys exhibiting a
moderate development of fiord characters. But the town
132 ALASKA GLACIERS
itself stands on a foreland carved from the rock, and this
foreland slopes gradually under the water of the sound or
bay. In detail the foreland is even more rugged than that
of Annette Island, and where it passes beneath the water
its eminences give rise to a great number of islets, which
stud the sound and form the natural breakwater of Sitka
Harbor. ‘The relations of mountain, foreland and islands
are well shown in plate xvi (lower view) and figure
65, which represent Cape Baranof, a few miles south of
Sitka. Here
also the in-
dicated base-
level has ap-
proximately
the height
of modern
== pepe. sea-level.
—
—=
; Ve About
FIG. 65. OLD PENEPLAIN NEAR SITKA.
° Wrangell
Seen from the timber line on Mount Verstovia.
and Wran-
gell Strait, a region on the landward side of the archi-
pelago, we saw more extensive tracts which probably
pertain to the same base-level. They stand somewhat
higher, averaging several hundred feet in altitude; and
the parts we saw best have been so modified by glacial
erosion that original base-leveling might not have been
inferred without the aid of the Annette and Sitka exam-
ples. They are illustrated by the upper view in plate
XVII.
Near the south end of Lynn Canal, Douglas Island is
separated from the mainland by a narrow fiord, the Gas-
tineau Channel. Facing the channel, the island is flanked
by the ruins of a high rock terrace (fig. 66). A dozen
short valleys of the island join the fiord at the level of the
terrace, which descends southeastward from an estimated
4
i ve
nee
ie
‘
Y
¢
<
2
MIF IO YVOITAY
AY aavAIWwod —.
gado ofl} awod nis
o bnaslo1ot wore
9,918 piodtsd oli
topeeth & to SLB
fistavom: oi to
eorle-s9t o199034
aru? .2 Hyd
= é;
fa !
a |
al avA GZAISAO
} dott teowrltuoe
d baslorot elt b
peedue nislqon:
stilw .20 o1meit
aitus) 1A A ye
EXPLANATION OF PLATE XVII
Upper Figure. — LOWLANDS NEAR WRANGELL
Standing south of the main town the observer looks southwestward
across the harbor. The narrow foreland on which the town stands,
and the peninsula beyond the harbor, are composed of metamorphic
rocks, and are probably remnants of a dissected and greatly worn pene-
plain. -: The rounded crests of the mountains beyond suggest that they
were overridden. by the Pleistocene ice-sheet. See page 132.
From a photograph made by E. S. Curtis, June 5, 1899. Negative
NO. 195.
Lower FicurE.— FORELAND AND ISLANDS NEAR SITKA
The view looks south and southwest from the hillside back of Sitka.
The islands of the harbor, and the foreland beyond, Cape Baranof, are
believed to be parts of a peneplain subsequently worn by a glacier.
See page 131, and compare figure 65, which gives a bird’s-eye view
of the same features.
From a, photograph made by E. S. Curtis, June 16, 1899. Nega-
tive No. 236.
VULIG UVUN SANVIST GNV CNV Tadeo
NO1SO8-NOS13 SiLUund Ag 'OL.ond
,
TIHONVUM LYOJ UVAN SANVIMOT
SiILYND AG ‘OLONRG
NOLSOG-NOS13
MAX BZlvVTd HI ‘IoA aw H
Me
i
&
5 eae
\ ae?
a yaa)
Vv he
rath
ied Neby SP,
ve
“ 7,
a5 Ag
ot) ”
in +)
Wis
;
a)
ts
y Hh
a \
‘
HL
Shey |
piky
he
o
ot
AK if
Lott
a
133
LOW PENEPLAINS
*‘MOTSOJa [eIOL]s Aq popunol a1B S}IWIUINS sy, “19; 9} DAOGB Joaj porpuny
[BI9AIS 2O¥III} Te[NZa1sy ue Suoye uado puvyst aq} Jo SAd][VA DUT, “HUNTED NveutyseD PUL BPEp III) JAAII[S 94} Sso19e ysaMYINOS SAOOT JOAIISqO 4,
‘avanal woud ‘GNVISI SVIONOG ‘99 ‘Ola
te Ce Oa GF LW Cu Se Osa Se. eS SS SO et PS Se ae. ls |” A
oo So Reha Vege meta Get oe ea ass eed
~ —
ove Rete we SG Do ty & © om ° @ 23 Bie 6 oy Oa a
SS = oa Wi, & "an ag a2 wo ® Bega 6 hie © op
3 ae oe eon St bn oe oon “es ev a Gm Om Fw yg, . .«— @
» O a oi, Goo Aw » & aeanmiunuka ht # y —_ e¢G o Goer
SReoaekeMtp,pekhbhouvues se PeaRA Pe Sesgeagey, MOB. &
= »~O OO Go WG YO SE aes Ses 3} Sse Oh Gia ag Baas =
SH Me HHP YP BSH HH SP SD OO we Ay SBePAncs BS VoHPne OB OA aT
134 ALASKA GLACIERS
period that the chief pre-glacial erosion of the plateau
was accomplished. While the granite tables were being
dissected and the harder metamorphics worn into varied
and rugged mountains, flat valleys and plains were devel-
oped from the broader bodies of weak rocks.
A Lower Base-level. —'The degradation of the troughs
in which lie the channels, passages and straits among the
islands, and the fiords of the mainland, has been carried
far below the horizon of the lower peneplains. Close to
the Annette Island peneplain Clarence Strait has a depth
of 1,675 feet, and 50 miles farther north, where the
strait is narrowed by Cleveland Peninsula, a depth of
2,100 feet is recorded. Thirty miles inland from Annette
Island Behm Canal is 1,800 feet deep; and 60 miles in-
land, toward the head of Portland Canal, is a depth of 1,250
feet. The greatest recorded depth of Chatham Strait, 60
miles from either end and 25 miles inland from the Sitka
peneplain, is 2,900 feet; and its northward prolongation,
Lynn Canal, has one sounding of 2,475 feet. These fig-
ures are selected from charted soundings which indicate
great irregularity of bottom configuration; they are
maxima, and not averages; but the averages also are im-
pressive. Inthe main part of Lynn Canal (55 miles long)
the average sounding along the line of greatest depth is
1,300 feet. The similar average for the surveyed part (60
miles) of Chatham Strait is 2,000 feet; for Stevens Passage
1,000 feet, Frederick Sound goo feet, Summer Strait
1,100 feet, Clarence Strait 1,500 feet, Behm Canal 1,400
feet, Portland Canal 1,000 feet. These are all in the
region of the Alexander Archipelago. ‘The broad sound
east of Queen Charlotte Islands, called Hecate Strait,
ranges from 150 to 600 feet, and the narrow passages
east of it are somewhat deeper. Queen Charlotte Sound,
northeast of Vancouver Island, has a general depth of
600 feet and a maximum of 1,140; the Gulf of Georgia a
LOW BASE-LEVEL 135
rough average of goo feet and a maximum of 1,470; the
narrow passage joining the sound and gulf an average of
600 feet, with a greatest depth of 1,000. At the extreme
south Puget Sound has an average depth of 500 feet and
a maximum of 925.
With the possible exception of Hecate Strait, these
water-filled valleys are clearly products of erosion; and
it is probable, though not proved, that they are younger
than the low peneplains. Whatever the extent to which
they were hollowed out by rivers, they were afterward
greatly modified by glaciers; and the glaciers are respon-
sible for the conspicuous unevenness of their floors. The
demonstration of ice work is found in the thorough glaci-
ation of all bordering lands, to be presently described, and
in the sculpture of rocky islets, which have characteristic
moutonnée forms. Much of the unevenness, and espe-
cially the deeper basins, must be ascribed to glacial
erosion, but a share may also be referred to glacial depo-
sition.
Whatever the extent to which the hollows were deep-
ened and enlarged by glaciers, it is probable not only
that they were initiated by rivers, but that some of the
rivers sunk their beds considerably below present tide-
level. The most satisfactory evidence on this point was
found at the extreme south. In the Puget Sound region,
as shown by Willis, the ice movement was southward, a
lobe of the ice-sheet ascending the broad valley of western
Washington. This lobe made extensive modification of
the face of the country, but chiefly by deposition and only
secondarily by erosion. The system of troughs it left
behind are regarded as preexistent stream valleys, only
moderately scoured and straightened by the ice which
overran and occupied them.’
1Drift Phenomena of Puget Sound. By Bailey Willis. Bull. Geol. Soc.
Amer., vol. rx, pp. 111-162, 1898.
136 ALASKA GLACIERS
This interpretation by Willis seems to me reasonable.
The glacial deposits in the southern part of the Puget
Sound region are voluminous, and much of their material
is of distant origin. This is the place where the ice lobe
discharged its load, and it is not probable that in the field
of deposition the ice also developed by erosion a system
of narrow deep troughs. Regarded as stream valleys, the
channels of the sound tell of a pre-glacial base-level at
least 500 feet, and probably 1,000 feet or more, below the
present sea surface.
A few features seen at the north might be regarded as
confirmatory, but their interpretation is subject to con-
siderable doubt. They are apparent exceptions to the
general rule that at all low levels the sculpture forms of
trough walls are glacial.
But while the existence of a pre-glacial low base-level
is on the whole probable, its precise relation to present
base-level and the period of its duration are altogether
conjectural. To bring all parts of the deep channels
within reach of stream erosion it would need to be 3,000
feet below present sea-level in the region of the Alexander
Archipelago. Under present climatic conditions, such a
change would carry a very large area above snow-line,
and would so promote the alimentation of glaciers as to
flood the whole district with ice and abolish stream ero-
sion. Stream erosion, therefore, could not have been
carried, by lowering of base-level, to the lowest parts of
the channel system without the aid of important climatic
variation. Without doubting the possibility of wide range
in independent climatic factors, it seems easier to assume
that the lowering of base-level was comparatively mod-
erate, and that a considerable part of the down-cutting of
the channels was accomplished by Pleistocene glaciers.
There is equal doubt as to the duration of the low
base-level, or the extent of the erosive work it enabled
LOW BASE-LEVEL 137
the streams to accomplish. The questions whether the
broader channels of the archipelago were merely outlined
by river gorges or were widely opened, whether the low
peneplain was only trenched or was largely replaced by a
peneplain at a level now submerged, whether the grading
of river beds was restricted to the coastal district or was
carried far into the interior, are not answered by any facts
in my possession.
To escape the confusion arising from the glacial re-
modeling of water-wrought topography, it is natural to
turn to the region just outside the glacial district. This
region may be assumed to have shared the same oscilla-
tions of base-level, so that whatever history may be derived
from it can be transferred to at least the neighboring parts
of the glacial district. The glaciation of what may be
called the inner coast has its southern limit in Puget Sound.
As the Olympic Mountains, separating the sound from the
outer coast, contained Pleistocene glaciers, the outer coast
also may have been modified by ice in that latitude. But
farther south the coast was not directly affected by glacial
ice. Between the Olympics and the mouth of Columbia
River are two shallow bays, partitioned from the ocean by
sand spits. The more northerly, Gray Harbor, receives
the Chehalis River, a stream of moderate size, but the
map gives no indication of a delta. Willapa Bay receives
two small streams, Willapa and Nasal rivers, and these
also are without deltas. It is evident that the bays are
estuaries, or submerged portions of the river valleys, and
they indicate a recent change in the relation of sea and
land, the sea rising or the land sinking.
Columbia River also ends in an estuary, its banks grad-
ually separating, until near the sea they are ten miles
apart. The estuary is shoal, and it is a matter of observa-
tion that the parts protected from the current are being
rapidly filled by the abundant silt of the river. The banks
138 ALASKA GLACIERS
are in part low, but include also hills and bluffs. While
this estuary is much larger than those of Chehalis and
Willapa rivers, it is small in relation to the Columbia
River, which carries a great volume of water, and the val-
ley whose submergence it records was of very moderate
dimensions. This valley was of course formed while the
river ran at a lower level, but the erosive work accom-
plished at that level was surprisingly small. As the con-
tinental shelf is narrow along this part of the coast, the
river may be supposed to have promptly graded its chan-
nel to harmony with the depressed base-level, and the
conditions would seem to have been favorable for the
development of a broad and branching valley like that
submerged in Chesapeake Bay. The fact that no such
development took place seems to indicate either that the
lowering of base-level was small or that the period of low
base-level was short. Despite the great volume of the
river, the valley developed by the discharge at lower level
was quite insignificant in comparison with the fiords and
channels of the neighboring glaciated coast.
These features would have an important bearing on
the question of low base-level in the district of the inside
passages if we could be sure that the history of the
Columbia estuary was really pre-Pleistocene; but there is |
reason to suspect that the Columbia has somewhat re-
cently come into possession of the lower part of its valley.
After passing the Cascade Mountains it turns northward
in the great structural valley which farther south contains
Willamette River and farther north holds Puget Sound.
Then at the mouth of the Cowlitz it again turns westward,
and traverses a low range of mountains or hills in a some-
what narrow passage. Close to the river these mountains
have a height of 1,000 feet or more. From the mouth of
the Cowlitz northward to Puget Sound the country is
comparatively low, and the summits are occupied by
GLACIATION 139
Pleistocene gravels. These features, while not demon-
strative without further study, clearly suggest that the
Columbia may formerly have followed the structural val-
ley northward to and through Puget Sound, reaching the
ocean by way of Fuca Strait. The occupation of the
strait and sound by the great Pleistocene glacier would
have compelled the river to find some different course,
and when it had once carved a channel through the coastal
hills the filling of its previous channel by glacial gravels
would prevent its return to the earlier course.
In view of the possibility that the lower course of the
Columbia dates only from the Pleistocene, it is evident
that the character of its estuary has no decisive bearing on
the problem of pre-Pleistocene base-level.
Summary.— Before the great glaciers of the Pleistocene
began their work the district included a varied topography.
The larger part was mountainous in the ordinary sense,
with crests at various heights and a complicated system of
steep-sided ridges, spurs and gorges. There were exten-
sive remnants of a high-lifted peneplain, its plateaus mark-
ing the areas of most resistant rock, and above these
plateaus rose summits of the nature of monadnocks.
There were remnants of a low peneplain—a peneplain
which is now near sea-level—and these occupied areas
of relatively weak rock. There was a system of river
valleys or master lines of drainage, narrow where the
rocks were most resistant and more open among weak
rocks. The bottoms of these valleys were in part below
tide-level.
Glaciation
Rounding of Angles.— Turning now to the results of
Pleistocene ice erosion, one of the most evident is the
rounding of salient features. Where the slopes of moun-
tain spurs have an average inclination as steep or steeper
than that which permits the resting of talus, the inter-
140 ALASKA GLACIERS
mediate crest line is normally acute and serrate. The
association of steep slopes with rounded summits is an
abnormal condition requiring special explanation, and in
glaciated districts there is a strong presumption that the
rounding has resulted from the removal by ice of the
salient parts of the spurs. ‘The rounding, therefore, serves
to show the extent of the district which has been subjected
to glaciation. It also affords a rough measure of the depth
to which the erosion has locally extended, for the imagi-
nation restores, more or less truthfully, the original sharp-
crested form, and thus realizes the difference between
that and the rounded form presented to the eye.
In the district under consideration the work of round-
ing has been extensive. Below certain levels the crests
and profiles of hills, mountains and mountain spurs are
devoid of crags and sharp angles and have curved outlines.
From this general rule there are no deviations within the
range of our observation, except where it is evident that
the forms of glacial sculpture have been modified by later
work of torrents or breakers. The rounding is more
thorough at low levels than at high. Near its upper limit
it often amounts only to the removal of pinnacles and the
blunting of angles which would otherwise be sharp;
farther down it has not infrequently been carried so far
that no suggestion remains of the pre-glacial forms. In
many places the depth of rock pared away in the mere
smoothing of a rough topography must have amounted to
several hundred feet.
The upper limit of rounding was estimated to range
from 3,000 to 5,000 feet in the region of the inside pas-
sage, and these estimates are in substantial agreement
with data given by the maps and photographs of the
Canadian Boundary Commission. From the latter I esti-
mate the height at 4,500 feet near Behm Canal (fig. 63)
4,000 feet near Berner Bay (fig. 62), 5,000 feet above
GLACIATION I4I
Chilkoot Lake (fig. 77), and 3,500 to 4,000 feet near
Brady Glacier (fig. 61). In the neighborhood of Sitka it
is about 2,000 feet.
In a general way this limit records the extreme height
locally attained by the confluent ice of the Pleistocene.
As the line often runs among modern névés and glaciers,
where glacial erosion has been in progress ever since the
maximum ice flood, there is possibility that the later
development of cirques has, in places, carved out sharp
blades and pinnacles from summits that had been rounded
by the earlier flood, but this qualification is not believed
to be important. The upward diminution of the paring of
salient angles is such as would naturally obtain near the
upper limit of ice action.
My observations of the limit of rounding are not so dis-
tributed as to give a comprehensive picture of the extent
of the maximum ice-sheet,
but they agree fully with
Dawson’s conclusion that
the whole district was oc-
cupied. Where now are
sounds and channels the
ice depth was _ probably
from 3,000 to 6,000 feet, FIG. 67. A FIORD OF THE INSIDE PASSAGE.
but many summits were ‘he tops of distant mountains were smoothed
ice-free. Some of the un- and blunted by overriding ice.
covered peaks were nunataks, about which ice currents
parted to unite again. Others were the culminating
points of mountain masses which served as centers of
glaciation. :
Cirques. — Other features due to ice sculpture are cir-
ques. These occur at all altitudes above 1,000 feet, being
most abundant in the higher regions. ‘Those above 3,000
to 3,500 feet now contain névés, and it is probable that they
have been occupied not only since the last maximum of
142 ALASKA GLACIERS
glaciation, but in interglacial epochs and during a part of
pre-glacial time. ‘Therefore, only a part of the erosion
they represent can be ascribed to Pleistocene ice. Those
at lower levels were made under Pleistocene conditions
and belong strictly to that epoch. It is noteworthy that
they occur considerably below the upper limit of ice
sculpture; on Kupreanof Island and in Glacier Bay they
were seen on the flanks of mountains whose summits are
well rounded. Though these lower-lying examples are
less fully developed than those about the higher summits,
they represent a notable amount of ice work, and that ice
work was performed during stages of glacier development
intermediate in extent between the modern and the maxi-
mum.
Fiords and Hanging Valleys. —'The fiords admit of
a partial classification as longitudinal, or strike, and trans-
by Ry Pa
mya EZ 2) Uy phi}
YY intel
ne ZL “a9
ZZ sy
a) yy
i}
es
igs Zee
oN 2
FIG. 68. A FIORD OF THE INSIDE PASSAGE.
Ice-rounded mountains in the distance.
verse. Where the courses are direct and accord with
the general trend of the coast, and especially where two
or more fiords or channels are parallel, it is fair to assume
that their positions were determined by structural factors.
Where the courses make wide angles with the trend of
FIORDS AND HANGING VALLEYS 143
the coast, and are in detail characterized by short turns,
it may be assumed that they are independent of strike.
In the case of strike fiords, erosion may have been favored
by the presence of weak rocks, but the erosion of trans-
verse fiords had no such aid. Our best opportunities for
direct observation were of fiords that either probably or
possibly follow the strike, and the discrimination of
aqueous and glacial erosion, or the problem of the amount
of glacial excavation, is thus complicated by a factor in-
volving much uncertainty.
Discovery Passage and Johnstone Strait, separating
FIG. 69. HANGING VALLEY ON VANCOUVER ISLAND.
Photographed from Johnstone Strait. In the distance, an ice-rounded summit.
part of Vancouver Island from various minor islands and
the mainland, constitute a well recognized fiord for 70
miles. With little exception, its walls of rock are steep
at the water’s edge and for some distance above and be-
low. The central depth of water ranges from less than
144 ALASKA GLACIERS
200 to more than 1,000 feet. The immediate walls are
1,000 to 2,000 feet high, curving back to rounded sum-
mits. On the mainland side the fiord is joined by many
troughs of similar depth and character, and by a few
hanging valleys. From Vancouver Island it is joined by
many hanging valleys. The sills of the hanging valleys
best seen lie from 200 to 500 feet above tide and are evi-
dently carved from the rock. Below each sill the con-
tours of the main trough are continuous, without any de-
flection toward the side valley, and the draining stream has
only begun the work of grading its channel. A shallow
trench is cut on the edge of the sill, and escaping from
this, the water tumbles down the open face of the fiord
wall. Other valleys hang so high that from our low point
of view we could not look into them. At a moderate
estimate the highest seen are 1,000 feet above the water,
and as these occur opposite the deeper part of the chan-
nel it is probable that the maximum discordance of valley
floors is not less than 2,000 feet. All the hanging valleys
appeared to be steep-sided glacial troughs, and those we
saw best are at least several miles in length, with moun-
tains behind them. :
For this complicated system of troughs I have not been
able to suggest an origin that does not involve an immense
amount of excavation by ice. The hypothesis demanding
least of the ice is one which assumes the main fiord to
follow a belt of weak rock,in which pre-glacial streams
had sunk their beds rapidly, outstripping such small trib-
utaries as had strong rocks to contend with. Under
such conditions, all pre-glacial valleys, with the possible
exception of those in the weak rock, would have been
narrow gorges, and the work of the ice in enlarging them
to existing dimensions would be at least as great as the
preceding work of the streams. While this work was be-
ing done by the tributary glaciers, the trunk glacier may
FIORDS AND HANGING VALLEYS T45
readily have carved from the weaker rock all that part of
the fiord trough lying below tide-level.
The hanging valleys seen on Vancouver Island were
evidently shaped by ice currents originating on the island
and directed toward the mainland. During their existence
the island contained a center of ice distribution. The
general condition of the district at this time has been
worked out by Dawson from studies of the strie and
other features of ice sculpture, made along the coasts of
Vancouver Island, of the neighboring mainland, and of
various smaller islands in the intervening sound. The
principal flow of ice was from the mountains of the main-
land, taking the form either of wide individual streams or
of a great confluent sheet; and this flood, banking against
Vancouver Island, was divided and deflected. One great
division, the ‘ Queen-Charlotte-Sound Glacier,’ moved
northwestward to the ocean, spreading over the north end
of the island. nee
Theother great ‘Wf
division, the
‘Strait-of-Geor-
gia Glacier,’
moved south-
eastward and
then turned
westward to
the Strait of i= == =
Fuca Itis ny aie
- 70. H. I ALL
probable, also, FIG. 7 ANGING VALLEY ON PRINCESS ROYAL ISLAND,
B. C., SEEN FROM FRAZER REACH.
that a branch of
this stream, reinforced by tributaries from the Cascade
Range in northern Washington, flowed southward as the
Puget Sound Glacier.
- 1 Additional observations on the Superficial Geology of British Columbia and
adjacent regions. By George M. Dawson. Quart. Jour. Geol. Soc. London, vol,
XXXVI, p. 278, 1881.
= nm)
i,
,
Wir
146 ALASKA GLACIERS
The thorough rounding of crests on Vancouver Island
extends so far above the floors of the observed hanging
valleys as to indicate that their glaciers were not features
of the stage of maximum glaciation. It is quite possible
that the greatest flood from the mainland turned back the
feebler streams originating on the island and sent currents,
here and there, through mountain passes to the southwest-
ern coast.
Along the narrow passages separating Princess Royal
and Pitt islands from the mainland, hanging valleys are
| : equally abun-
; dant, and the
illustrations of
the physio-
graphic type
are even more
striking. The
greater tribu-
FIG. 71. HANGING VALLEY, FRAZER REACH. tar y va 1 1 e y S
Ice-rounded summits in the distance.
approach the
fiords from the mainland and have sills near water-level,
some of them lying so low as to contain shallow bays.
All of the sills on the side of the islands are above tide,
and the valleys back of them are surprisingly broad when
considered as the channels of glaciers originating on is-
lands only fifteen to twenty miles wide. The change of
gerade from the floor of the hanging valley to the side
wall of the main valley is so abrupt as to give the impres-
sion that the sill is really a parapet, and that the alcove in
the fiord wall contains a basin. At one point (fig. 70)
we climbed to a sill with the half expectation of discover-
ing a lake beyond, but found only the uneven, and in
places marshy, floor of an ordinary U-trough. The high-
est sills seen are about 1,000 feet above tide.
As Grenville Channel, the passage separating Pitt Is-
FIORDS AND HANGING VALLEYS 147
land from the mainland, is straight, and as it has a parallel
on the opposite side of the island, it is confidently classed
with the strike valleys. At each end it connects with
much wider fiords of the mainland, having the crooked
courses of transverse valleys. From these relations I
infer that the pre-glacial master drainage was transverse,
and that the Grenville valley was not followed from end
to end by a
pre-glacial
stream, but
contained two
streams, flow-
ing in opposite
ways from a
medial sum-
mit. The pas-
sage about.
Princess Royal Island is not clearly marked as a strike
valley, but its narrowness as compared with the trans-
verse valleys in which it ends indicates that it origi-
nally contained two minor streams, with a summit be-
tween. No trace of either summit has survived the
glacial remodeling. As in other fiords, the bottoms are
irregular, but some of the lowest points lie midway be-
tween the ends. In fact, the deepest soundings reported
in the two passages (severally 800 and goo feet) are near
their middles, and are not exceeded by recorded sound-
ings in neighboring waters. When it is considered that
these fiords, being parallel to the coast, run athwart the
general movement of the ice from land to sea, the fact
that their depth is comparable with that of troughs lying
in the direction of general movement is certainly remark-
able. It probably depends in part on the presence of a
belt of easily eroded rock, but after all allowance for such
favorable condition, one is impressed by the ability of ice
——“- y
FIG. 72. HANGING VALLEY, FRAZER REACH.
148 ALASKA GLACIERS
to cut down its bed far below the profile which limits the
action of running water.
The essence of the explanation is contained in Gan-
nett’s theorem
that the glacier-
fon Pee rag made valley is
Soe! teem AY ,{/ homologous, not
< ; ‘aS Ae Vas with the river-
yy See g'| made valley, but
a oi gi) with the chan-
YAY, nel made by the
eet river. The bot-
" tom of a river
channel is not
evenly graded
like its flood
plain, but it
abounds in hol-
lows and hills,
and the bottom
ofa glacier chan-
nel has irregu-
larities that are
similar but on a
larger scale.
A phase of the
Pleistocene con-
dition of these
passages is illus-
trated along the
The inlet occupies a glacial trough entering Grenville Channel base of the Fair-
from the east. weather Range
from Icy Cape to Cape Fairweather. A foothill ridge, 35
miles long, is separated from the range by a nearly con-
tinuous groove. <A dozen alpine glaciers descend to the
‘ Lr
rave -
- :
-
< ot oat
FIG. 73. NORTH WALL OF LOWE INLET.
149
FIORDS AND HANGING VALLEYS
‘XV VAQLIT AO aGvVaH +4 ‘914
1 = <T
RY VY}, hf Vee 4 Ls fiz
Ae Wy a STS Ail 5
yh \vs Nie NVA | MESSE:
arn CEREALS
’ f pp
aw?
MY,
Aas
mar Jf tienen a
2 a eae ae
VIA gue § ns eel
Vs meat ® Lf aA yy;
La oi 4/ Le “yp Me me OY eee
a : 4 : 4
. yi Yay , y a Y
hin ox dy N/M FY. 0 RS PPE es
a ae a en 7 {opty
OS et a ; ems
AY:
150 ALASKA GLACIERS
groove and are there gathered into trunks which follow
the groove lengthwise till escape is found through some
break in the ridge. The surfaces of trunks and tributaries
are mutually adjusted where they join, but it is easy to
imagine that the progressive erosion of their beds is: re-
lated to the volumes of the glaciers, and that the greater
ice streams have the deeper channels. It is interesting
to note in this connection that the bottom of this trough
is below present tide-level— at least in part—in spite of
the fact that there has here been a post-Pleistocene eleva-
tion of land. Figure 74 shows a portion of the trough
where it is occupied partly by glaciers and partly by an
arm of the sea. The observer stands on the foothill ridge.
Lituya Bay has the form of a letter T, the cross-bar ap-
pearing inthe view, and the shaft running through the foot-
hills at the right. ‘The large glaciers in the distance and
foreground reach the longitudinal groove from deep
mountain gorges. A small glacier, whose end barely
touches the water, cascades over a sill that may be 800
feet above tide. A hanging glacier at 2,000 feet or more
sends a tongue down a shallow groove in the steep wall
of the fiord. And, at the extreme left, a pocket glacier
occupies a hanging valley at an altitude of 3,000 feet.
The depth of the glacial excavation in the passages by
Pitt and Princess Royal islands was probably about as
great as in the passage by Vancouver Island. ‘The scale
of the topography is not far different, the evidence from
hanging valleys is equally cogent, and the case is strength-
ened by the presumption in favor of pre-glacial summit
levels. Even with a low base-level it is not at all prob-
able that pre-Pleistocene streams carried the erosion of
any considerable part of these troughs below present sea-
level, and the water partings within them may well have
been a thousand feet higher.
One of the more important passages of the Alexander
STRIKE FIORDS I51
Archipelago is so direct in its course that a straight line
190 miles in length could be laid out upon it without
touching either shore. It heads in the mainland at the
extreme north and, trending a little east of south, termi-
nates in the Pacific coast. The southern three-fifths, which
bears the name Chatham Strait, has an average width of
about seven miles; the northern two-fifths, known as -
Lynn Canal, averages five miles. Our direct observation
-was restricted to the northern part.
This straightest of all the passages is also deepest. No
soundings have yet been charted for the southern third,
but those of the northern part indicate that a continuous
channel can be traced with 7oo feet as its minimum
depth, and the maximum depth, as already mentioned, is
2,900 feet. The bounding mountains, so far as we saw
them, are 4,000 to 5,000 feet high, and the full depth of
the trough is in the neighborhood of 6,000 feet. At its
head the trough divides into four parts, which penetrate
the upland, first as fiords or inlets and then as river val-
leys. These parts diverge from their point of junction
like the ribs of a fan, their directions ranging from north
to northwest; and their courses are remarkably straight,
especially in the lower parts.
The unusual straightness of this great trough naturally
suggests that its course was determined by some struc-
tural feature, such as a fault or the outcrop of an easily
eroded rock. Its breadth is in better accord with the
second of these tentative explanations; but the matter is
not free from doubt. If the trough is a strike valley, we
should naturally expect to find parallel valleys associated
with it, but the number of such is limited. A short
parallel trough lies fifteen miles west of Lynn Canal
and contains Excursion Inlet. East of Chatham Strait
are Seymour Canal and Stevens Passage, which are
approximately parallel. But a number of other features
ALASKA GLACIERS
152
‘}29J C009 ULT]} SST JOU SBM Jo[UY BAIL]
Uy I} SuI00}sfoq JO Yidop oyT, “<Supunoy-sor yo auoz 94} aaoqge Ap} YSIs Joolord ‘Bry 429 c00'S pure ooz'S ‘J J9] SW917K9 pue 4Y 311 9uI93}x9 94} ye sxvad ay
*}99} C0o'S ATWO ST YIpPTA SPT sty A ‘soTIUT [VIVAaS IO} 399 COP'r Jnoge Jo YIdaplesyus. B sey joruy eArey, ‘daap yaoz oF
PUB opts SaTIM Hz St [eueD uUA’T Jo yred a[qisia ayy *(4L By) axe] & OSTe sute}nOD JOOATIYD oy, “Asats v Aq pred uy puv vas aq} Aq red ur pardnaoo st youy
‘eATEY, pure soqetag ‘(721 3¥) JOORTIYD ‘sayouesq Jy} sj} oas pus ‘ya UJ FEATIYD PUL VOISIAIp ulew s}T WseA\jeq B[NsuINAd 34} MoI [eUL ay} dn Yoo] am
“IVNVD NNAIT 4O avaH ‘Sl ‘ola
wl enn SERS .
: : : > °
=> = c = : errs ~- =
z z a ire eS 53 SNe
peel 4 ae FEE See See =
.s~ oO cm, ee ape SS, NSIS NSS
tne SESS
STRIKE FIORDS 153
in close association exhibit a systematic northwest trend;
these are Icy Strait, Freshwater Bay, the main part of
Tenakee Inlet, and Peril Strait with its prolongation in
Hoonah Sound. The divergence of the branching fiords
at the head of Lynn Canal is also perplexing; for, while
each of these is so straight as to suggest an origin con-
nected with strike, they are not parallel, but diverge fan-
wise from a common point.
The walls of Lynn Canal are well-defined features. At
the water’s edge and for some distance above, their con-
tours aresimple. There are few bays and no jutting prom-
ontories. The slope of the walls is not so steep as in
some fiords; it rarely exceeds 45°, and in places is as low
as 30°. Near the head of the canal the walls are well
defined up to an altitude of about 2,000 feet, the height
increasing toward the north and decreasing toward the
south. Higher up, the mountains exhibit a varied topog-
raphy: There
are U-shaped
troughs end-
ing as hang-
ing valleys at
many differ-
ent heights;
there are V-
shaped gorges
modified at
bottom by
glaciers and
The sill of the hanging valley is 3,500 feet above sea-level. For
separated by more than 1,000 feet below the glacier the fiord wall is kept bare by
narrow ten ti- falling fragments of ice.
form spurs. These troughs, gorges and spurs approach
the canal wall at all angles and there end. Some-
times they end abruptly, sometimes with a certain amount
of prolongation down the steep wall; but this prolon-
FIG. "6. HANGING GLACIER, TAIYA INLET.
154 ALASKA GLACIERS
gation never extends to the water, and usually does not
affect the slope within one or two thousand feet of the
water. Their relation is such as might arise if the topog-
raphy of the upland had formerly extended farther in the
direction of the main trough and afterward been truncated
by the development of the trough.
The branch troughs which unite to form the canal
have similar walls, which rise higher before meeting the
varied topography of the upland. They are also narrower,
and at least two of them contract in their upper parts so
~~ Lf, ALE
VI oy
tf): ¥ A
\ ¢ Mi fe
Wz. WY PD
Yl LLEEZ Le ZZ Zi y —Yy yy,
oy 4
FIG. 77. NORTHEAST WALL OF THE CHILKOOT TROUGH.
Below is Chilkoot Lake, and beyond are Chilkoot Inlet and Lynn Canal. The lower part’
of the mountain was shaped bya great Pleistocene glacier, the upper by small tributaries,
which survive. The summits are ice-rounded nearly or quite to 5,000 feet. The floors of hang-
ing valleys are at 3,500 to 4,000 feet.
that the cross-profile is more nearlya V thana U. Skag-
way Canyon, a tributary to the Taiya trough, is narrow at
bottom, except where occupied by alluvium. Glaciation
has smoothed its walls on a grand scale, and has degraded
its bottom enough to render the floor of a tributary dis-
cordant to the extent of 50 or 100 feet, but the type of
cross-section acquired from pre-glacial stream erosion has
not been destroyed. Photographs show that the upper
STRIKE FIORDS 155
part of Taiya Valley has a similar character, and it
seems to me probable that these gorges have been only
moderately deepened by glaciers. The pre-glacial stream
grades which they suggest would pass below present tide-
level before reaching the head of Lynn Canal, and would
be adjusted to a quite low base-level at the south end of
Chatham Strait.
The bottom of the main trough is characterized by much
WH YVAVVVWJJJC=/-
FIG. 78. PROFILE FROM TAIYA PASS SOUTHWARD.
The profile follows the lowest line through Taiya Valley, Taiya Inlet, Lynn Canal and
part of Chatham Strait. Whole distance 165 miles. Vertical scale about ten times the hori-
zontal. Base line 3,000 feet below sea-level. The approximate height of mountains east of
the trough is indicated.
irregularity. The line of deepest water is sinuous and
often wanders far from the middle, and along this line the
depth varies irregularly (fig. 78). The soundings are
Preis Pp VPr=:
Y/7 ys
CTX.
OEP VME EEL.
FIG. 79. CROSS-PROFILES ABOUT HEAD OF LYNN CANAL.
Based on contour map by Canadian Boundary Commission and soundings by U. S. Coast
Survey. The positions are indicated by corresponding letters in figure 78. Profile A crosses
Chilkoot Lake (fig. 75), Ferebee Inlet and Taiya Inlet. Profile B crosses Chilkat Inlet, near
Davidson Glacier, and Lynn Canal. Profile C crosses Lynn Canal below Sullivan Island.
S. L., sea-level. Base line 3,000 feet below sea-level. Vertical scale same as horizontal.
too far apart to give expression to details of configuration,
and we do not know to what extent the irregularities may
156 ALASKA GLACIERS
be ascribed to unequal deposition of drift, but there is
reason to believe that much of the inequality pertains to
the rock floor and is to be ascribed to glacial erosion
as conditioned by varying resistance of the terrane. A
number of islands and one long peninsula are so placed
that they may properly be regarded as portions of the
trough bottom which rise too high to be covered by the
sea. They are of rock, are thoroughly glaciated, and their
axes, as well as all flutings and other lines of sculpture, are
parallel to the fiord walls. Ice erosion has gone so far as
to destroy all semblance to the forms characteristic of
aqueous sculpture. Several islands and the southern
part of the peninsula are shown in figure 3, and the view
in figure 75 was made from the summit of the penin-
sula, 1,750 feet above sea-level.
From these various facts, as well as from general im-
pressions to which it is not easy to give definite expres-
sion, I would draw the following tentative inferences: The
V-gorges at the heads of branches of Lynn Canal and in
the uplands bordering the canal, were made chiefly by
pre-glacial streams, and they have been but moderately
deepened by glaciers. There was a pre-glacial, com-
paratively narrow, valley through Lynn Canal, the floor
of the valley being below present sea-level and related to
a low base-level. Lateral V-gorges were tributary to
this and were largely adjusted to it in grade. The Pleis-
tocene glacier broadened the river valley, truncated the
side spurs and the tributary gorges, and at the same time
materially deepened the valley for the whole breadth of
the trough. The glacial degradation is conceived as
averaging hundreds of feet and possibly more than one
thousand.
The lateral valleys so situated as to carry glaciers under
other than Pleistocene conditions, are thoroughly shaped
in characteristic U forms, and they now contain glaciers.
STRIKE FIORDS 157
There are also valleys which are now free, or nearly free,
from ice, and which were filled with ice only in the
presence of the great glacier, and these have less charac-
teristic glacial forms. It would seem that the presence
of the great glacier in Lynn Canal gave them so high a
base-level that their ice streams were sluggish and had
little power of erosion.
The valley of Davidson Glacier deserves special men-
tion as an illustration of the broad contrast which may
exist between the systems of currents associated with
different stages of glaciation in the same district. The
névés supplying the glacier are not in sight from Lynn
Canal, but lie back of the first line of summits, and the ice
river flows eastward through a lateral or transverse valley,
entering the great fiord approximately at right angles.
During the great ice flood the general direction of move-
ment was toward the south, and Davidson Glacier did not
exist; its valley was not only filled with ice but over-
ridden. It results that the upland bordering the Davidson
trough in the vicinity of the Lynn trough, is planed and
fluted with lines trending southward, while the Davidson
trough, being shaped wholly by the Davidson Glacier dur-
ing epochs of moderate ice supply, has an entirely inde-
pendent sculpture, the lines of which are transverse to
those of the overlooking upland. The Davidson trough
is a fine example of its type. So far as visible from the
sea, it is of uniform width; its parallel walls sweep ina
simple curve of large radius and are steep. Although
the topography just above and back of them is varied, they
themselves have neither salient nor reentrant angles. The
glacier has evidently adjusted its channel quite com-
pletely to the conditions of its flow, and has at the same
time sunk itself deeply into the mountain it traverses
(see fig. 2).
The transverse troughs of the mainland we did not
158 | ALASKA GLACIERS
visit; they are known to me only through photographs,
the contour maps of the Canadian Boundary Commission,
and the soundings of the United States Coast Survey.
As already mentioned, they are judged to be transverse
to the strike, because they make wide angles with the
general trend of the coast and because they are charac-
terized by manyshort
turns (fig. 80). Be-
ing independent of
strike, their courses
are also independent
of variations in rock
texture, and this
character makes
them specially avail-
able for the study of
glacial erosion.
“Sie, | ‘Theirwalls are steep;
-—WIE | photographs give the
f, | impression that they
are decidedly steeper
than those of Lynn
Canal’ and 18
branches, but this
FIG. 80. MOUTH OF SPEEL RIVER. impression is pos-
The river is rapidly filling its deep trough withalluvium. «j e to th e ten d-
Glacial rounding extends above the base of clouds, which sibly du
cut off the view at about 3,000 feet. ency of photo graph-
ers to select localities exhibiting bold scenery. The
walls stand well apart, after the habit of glacial troughs,
and exhibit notable parallelism (fig. 62). Hanging valleys
abound, ranging in height up to 3,000 feet or more and being
more numerous at the greater altitudes. Some, like the
Stikine and Whiting, are occupied by rivers; others, like
the Taku, Speel, Unuk and Skeena, contain rivers in their
upper parts and admit the sea below; others, like Tracy
TRANSVERSE FIORDS 159
Arm, Behm Canal and Portland Canal, have the character
of fiords through their whole extent. Where rivers flow
through them, the whole width from wall to wall is
occupied by alluvium, and a lace-work of channels indi-
cates rapid deposition. The open water has the depth,
and the irregularity of depth, characteristic of fiords. In
Tracy Arm, which has a breadth of one mile and a length
of twenty, the soundings range from 850 to 1,150 feet.
~The main part of Behm Canal, with a width of two to
three miles, has a depth ranging from 1,100 to 1,850 feet.
In Portland Canal, which for eighty miles has an average
width of two miles, the range of soundings is from 300 to
2,100 feet, and a depth of 1,200 feet occurs near the head.
It is scarcely to be doubted that all these long troughs
were initiated by pre-glacial rivers; but the rivers could
not have opened their valleys to the present width with-
out giving time for the breaking down of the walls. If
the river valleys were deep, they were also narrow, and
their widening was the work of the Pleistocene glaciers.
In the work of widening, the more obstructive projections
were removed and the contours of the walls were simpli-
fied. The amount of erosion necessary to convert the
assumed V-gorges into the observed U-troughs is large,
and the ice streams by which it was done could not have
failed to wear down the floors of their channels at the
same time. While it is quite possible that the down-
stream parts of the river gorges had been sunk below
present sea-level, the greater part of the excavation below
sea-level was probably performed by the glaciers.
Inequality of Glacial Erosion.— The great work
which it has seemed reasonable to ascribe to ice in the
deepening and widening of fiords and other troughs stands
in striking contrast to the feebleness of ice erosion in
other places, which permitted, for example, the preserva-
tion of the low peneplains of Annette Island and the
160 ALASKA GLACIERS
vicinity of Sitka. In the one case the depth of the ero-
sion is measured by hundreds of feet, in the other by
tens. To a certain extent inequalities of erosion were
determined by inequalities of resistance, but as the rock
of the low peneplain is not of notably resistant character,
and the rock traversed by the transverse troughs is in part
of highly resistant character, it is evident that this is
not the dominant factor. To an important extent also
differences of erosion were determined by differences in
the depth and consequent pressure of the flowing ice.
But I conceive that the most important of the variable
factors was the velocity of the ice currents. At the height
of the Pleistocene flood the snow-fields were on high pla-
teaus and mountain masses, from which the ice crept in
broad sluggish streams to the preexisting channels of
drainage. In these channels it assumed the character of
rivers, and the lines of pre-glacial water drainage became,
in the main, the lines of Pleistocene glacial drainage.
Along the deeper waterways the ice could flow more
rapidly because its depth was greater, and its ability to
erode was correspondingly increased. ‘Thus it was that
the old river gorges, being adopted as lines of flow by the
ice, were widened, straightened and deepened, while
the adjacent uplands received comparatively little modifi-
cation. The remnants of low peneplain were preserved,
despite the softness of their rocks, because they lay out-
side the lines of flow of the strong currents. ‘The remark-
able deepening of the fiords of the mainland is probably
connected in part also with the fact that they were longer
occupied by glaciers than were the channels of the archi-
pelago. Many of them still have glaciers at their heads;
others are flanked by glaciers which would descend and
fill them should the climate swing but slightly toward the
Pleistocene condition.
The more thorough rounding of salient angles at low
GLACIAL DEPOSITS 161
levels than at high is probably due to the concurrence of
several causes rather than to a single one. First may be
mentioned the difference in pressure. The rate of abra-
sion, and of other forms of erosion, is probably enhanced
by pressure, and during the height of the glacial flood all
low-lying surfaces were subjected to greater pressure than
those at higher levels. A second cause is connected with
duration. The coming on and the passing of each Pleisto-
cene epoch of glaciation was probably gradual, and there
were doubtless glacial epochs of less intensity than the
maximum. ‘Thus the crests of low hills were subjected
to glacial wear for longer periods than those of high spurs,
and the difference may have been very great. Some al-
lowance may also be made for subsequent modification at
high levels. Ever since the last great ice flood began to
wane, the valleys-between high spurs have been occupied
by small glaciers, and these have tended, by the develop-
ment of their valleys, to reduce the width of the separat-
ing ridges. Thus, while the rounding at low levels was
still in progress, a work had been begun which tended to
reduce the effect of the rounding at high levels.
Glactal Deposits. — In the narrower parts of the inside
passages we saw no accumulation of glacial drift. It is
possible that drift masses were concealed here and there
by the dense forest, but usually the spaces between cliffs
and other visible outcroppings of rock were not large. It
is probable that drift masses are concealed by the water,
_ and have share in the production of the irregularity of the
bottom; and a few bars and dams which are known to
interrupt the continuity of other fiords are presumably
morainic. As it is natural that the routes of travel should
avoid such obstructions, it would be rash to infer the ab-
sence of local moraines from our failure to observe them.
The only important bodies of Pleistocene drift which we
saw are on the shores of the Gulf of Georgia, where
162 ALASKA GLACIERS
several extensive banks of waterlaid material constitute
terraces, both on the mainland and on the shore of Van-
couver Island. These banks are flat-topped, and esti-
mated to rise from 100 to 200 feet above the water. One
of them was seen to overlap hills with distinctly glacial
sculpture, and as they are from 50 to too miles within
the limit of the glaciated district they must have been
accumulated after the last ice maximum.
The glacial deposits we encountered are of trivial mag-
nitude collectively, in comparison with the glacial erosion
of which we saw evidence, and it was therefore inferred
that the principal regions of glacial deposition lay outside
the field of our observation. This inference agrees with
the conclusion of Dawson that the ice-sheet embraced the
entire Alexander Archipelago, together with all other is-
lands of the coast except the Queen Charlotte, and that its
outer margin was beyond the present line of coasts.
Associated Sea-Levels.— The question of the relations
of sea and land at the time of the great Pleistocene glacia-
tion is of much interest, and some considerations bearing on
the question will be mentioned, although the evidence at
present available is either indirect or negative. As gla-
ciers are chiefly phenomena of the land, and as glacial
erosion in this district has been carried far below the
present sea-level, it is natural to assume that the sea-
level associated with that erosion was much lower. A
little consideration, however, will show that such a con- .
clusion does not necessarily follow. ‘The deepest known
hollow ascribable to ice work is in Chatham Strait, and
lies 2,900 feet below sea-level. At that point the total
depth of the great glacier was probably 6,000 feet. It is
commonly assumed that where a glacier enters a sea not
deep enough to float it, a part of the ice, equal in weight to
the displaced water, is upheld by the water, and the pres-
sure of the glacier on its bed is correspondingly dimin-
PLEISTOCENE SEA-LEVEL 163
ished. While I do not regard this assumption as valid,
I entertain it for the moment because it gives a minimum
estimate of the pressure of the Chatham Strait glacier.
If the then sea plane had the same height as the present,
the pressure of the glacier would be modified, by assump-
tion, by the sustaining power of 2,900 feet of sea water.
This sustaining power is equivalent to about 3,300 feet
of the total ice thickness, leaving 2,700 feet of ice to press
upon the bottom of the strait; and such a pressure would
manifestly be ample for the work of erosion. So far as
our numerical data go, this locality affords an extreme
case; and as the hypothesis of glacial erosion below
present sea-level is not barred for this locality, it is prob-
ably not barred for the whole district.
Another consideration is connected with the. reaction
of the ocean on the front of the glacier. My own obser-
vations, though comparatively limited, are so accordant
with Dawson’s generalization that I accept with confi-
dence his conclusion that the Pleistocene ice front lay
outside the present coast line throughout practically the
whole district. If the ocean had then its present level, it
washed the ice front for hundreds of miles. The power
of the ocean to waste a glacier by melting is ordinarily
greater than the power of atmospheric agents, and along
the present coast of Alaska is much greater. As the fac-
tors are complex, it would be difficult to give an analytic
demonstration of this proposition, but it is easy to illus-
trate by anexample. The great confluent glacier which
filled Glacier Bay in the eighteenth century had a general
depth of 1,000 to 2,000 feet along the axis of the bay, and
rested with less depth on adjacent tracts of land. All
through the nineteenth century it was depleted, its wast-
ing being brought about partly by the sea and partly by
atmospheric agencies. The sea not only melted back the
1See discussion in chapter 111.
164. ALASKA GLACIERS
front for 35 miles, but disposed of a continuous accession
of ice from the Muir, Grand Pacific, and other glaciers.
Of that portion of the confluent glacier which lay upon
the land, a part slid into the sea and was there melted, but
another part, which happened to rest on comparatively
flat surfaces, remained on the land and has been subjected
to only atmospheric agencies of waste. These agencies
have not yet completed its destruction, so that extensive
patches of stagnant ice, receiving no accessions from
névés, remain to testify to the comparative feebleness of
the atmospheric attack. I think there can be no exag-
geration in the estimate that the melting by the sea has
exceeded by ten times the melting from direct insolation
and the contact of warm air and warm rain. It is further
to be noted that this work of the sea was performed in a
land-locked bay, where water cooled by the ice tends to
accumulate and is but slowly exchanged for the warmer
water of the open ocean. On the outer coast, where the
supply of warm water would be constantly renewed by
currents, the melting power would be still greater.’
The warmth of the Pacific Ocean in this region depends
chiefly on the great circling current of the North Pacific,
a part of the planetary system of oceanic circulation which
might be modified but would not be stopped by any causes
‘we may suppose to have existed in Pleistocene time. All
through the Pleistocene the melting power of the ocean
along this coast must have been great, and it is not prob-
able that glaciers could so far have withstood it as to ad-
vance in deep water. The features of another part of the
Alaska coast, to be presently described, render it probable
that the glaciers were checked by the oceanic melting
somewhere in the belt of shallow water, and were com-
1 Muir Inlet near the glacier is 7,000 feet broad and 500 feet deep. Here Reid
found a general temperature, at all depths, of 38° F. The oceanic temperature
in the Gulf of Alaska is 58° F. The water of the inlet is 6 degrees warmer than
melting ice, that of the neighboring ocean 26 degrees.
PLEISTOCENE SEA-LEVEL 165
pelled there to yield up their load of rock waste. We
know, from the extent of Pleistocene erosion in this dis-
trict, that the burden of rock waste was large, and wher-
ever the moraines were built they made an important de-
posit. Ifthe Pleistocene base-level had been the same as
the present I should expect to find that deposit as a con-
tinuous bar, or string of linear islands, along.the outer
coast of the Alexander Archipelago and at various points
farther south, but no such features have been described,
and the coast seems to have an entirely different character.
This consideration, though connected at present with only
negative evidence, distinctly favors the theory that the sea-
level associated with the greatest Pleistocene ice floods
was considerably below the modern sea surface.
There is some evidence, on the other hand, of a com-
paratively high sea plane after the glacial maximum.
Dawson describes an extensive marine deposit, reaching
a height of 200 feet, on the east side of Graham Island, the
most northerly of the Queen Charlotte group, and infers
from its relations that it was contemporaneous with a
development of local glaciers. At Nanaimo, on the
inner coast of Vancouver Island, he found shell-bearing
marine clays, resting on glaciated rocks, at a height of 70
feet above the sea”. In Gastineau Channel is a narrow
shore terrace at a height of 200 feet, and in an associated
clay Dall found marine shells. At two, at least, of the
localities the shells are of species indicating cold water,
and each locality is on the border of a sound or channel
which would be filled with icebergs by a moderate devel-
opment of glaciers. Ifthe phenomena all belong to the
same chapter of Pleistocene history, they record an
episode similar to that of the Champlain clays of the At-
lantic seaboard.
1 Quart. Jour. Geol. Soc. London, vol. xxxvu, p. 281, 1881.
2 Quart. Jour. Geol. Soc. London, vol. xxxvul, p. 279, 1881.
166 ALASKA GLACIERS
The terrace about Gastineau Channel is rather con-
spicuous at Douglas, where the forest has been removed,
and was detected at several points where the forest still
stands, but I searched in vain for its continuation about
the shores of Lynn Canal and Cross Sound.
HIGH MOUNTAIN DISTRICT
Between Cross Sound and Prince William Sound are >
high mountains visible from the sea. They are much
loftier than those of the Inland Passage district, and
probably comprise a number of distinguishable ranges,
though their system is not yet known. A mass cul-
minating in Mount St. Elias (18,100 feet), west of Yak-
utat Bay, has been called the St. Elias Alps, and this
name is sometimes made to include the whole chain. A
more easterly portion, culminating in Mount Fairweather
(15,000 feet), is sometimes distinguished as the Fair-
weather Range. Opposite these mountains the coast line
is comparatively simple, being interrupted by fiords at a
few points only and having no important islands. From
Icy Cape westward the mountain base is bordered by a
low foreland, narrow at first, but broadening to ten miles
at Alsek River and fifteen miles at Yakutat Bay and
beyond.
Many alpine glaciers now creep down the face of the
range and unite in plateau masses on the foreland, a
few of them spreading to the sea. The foreland bears
also a system of ridges, of peculiar type, which are be-
lieved to be morainic and of Pleistocene age. Mention
has already been made of one of these in describing the
La Perouse Glacier. The ridge against which that glacier
crowds, at the point of our visit, runs parallel to the coast
for about seven miles and has an actual height of 1,000
feet, as indicated on the map of the Canadian Boundary
Commission. It is nearly straight, is steeper toward the
HIGH MOUNTAIN DISTRICT 167
land than toward the sea, and is contoured on the sea-
ward side by a terrace, which probably lies 200 to 300
feet above tide. At the single point of examination this
terrace contains marine beds overlain by glacial gravel,
and the ridge back of it appears to consist of unsorted
drift. ‘The clays, where seen in section, are in part level
-and in part disturbed (page 41). The completion of
the moraine ridge was subsequent to the deposition of
the clays. The undisturbed clays imply, by their posi-
tion, a higher stage of the ocean, and the overlying
gravels are more readily explained by assuming that the
sea-level was still high at the time of their deposition. It
seems to me probable that the moraine ridge was depos-
ited when the sea stood several hundred feet higher than
now against the land.
Toward the southeast the ridge ends against the side
of the La Perouse Glacier, and the relations indicate that
the glacier is wearing it away. At one time it probably
extended considerably farther in that direction, but was so
low as to be overridden by the modern glacier and thus
subjected to erosion by it.
Lituya Bay, a few miles up the coast toward the north-
west, penetrates the land for seven miles, dividing not only
the foreland but a low outer range of mountains. Within
the mountains its trough has fiord characters, and from the
walls of the mountain gateway run two morainic ridges,
parallel at first, but curving toward each other and de-
scending so as to unite under water at the entrance to the
bay. These were seen only from the ship’s deck, but
their character is unmistakable. They are steeper within
than without, and their inner contours continue those of the
passage through the mountain ridge. They extend some-
what beyond the general line of the foreland, making a
pair of capes which embrace the outer part of the bay.
Close to the mountains they have an extreme height of
168 ALASKA GLACIERS
1,000 feet above the sea, as indicated by the contours of
the Canadian Boundary Commission’s map.
Between Lituya Bay and the mouth of Alsek River
are several other morainic ridges, more or less crescentic
in form, and so related to modern glaciers as to indicate
that they were formed by them at some earlier epoch, when
the ice streams were greater than now. In some cases
the modern ice seems to extend to the base of the mo-
rainic rampart, and in one instance ice projects through a
gap in the rampart; but the height of the old moraines
forbids the idea that they were adjusted to glacial condi-
tions closely resembling the present. From a distant
view some were judged to be as high as 1,500 feet,
and the modern glaciers seemed merely to touch their
bases, instead of pressing against their inner faces. Asso-
ciated with them, and extending along the coast beyond
them, are a system of terraces, the highest of which was
estimated to be 500 feet above tide; and these suggest
that the sea surface stood comparatively high when the
moraines were built.
The fact that the old moraines rise far above the modern
glaciers but yet inclose areas only a little larger than the
modern ice is able to occupy, is notable, and doubtless has
an important significance if rightly interpreted. The ex-
planation which occurred to me is, that the extent of the
old glaciers was restricted by contact with sea water. As
already pointed out, a warm ocean, like the Pacific in the
Gulf of Alaska, is a most efficient agent for the wasting
of glaciers. The high specific heat of water, the freedom
of the circulation by which warm water is brought to re-
place the water which has parted with its heat, and the
great depth of the body of warm water on which this cir-
culation can draw, all contribute to this efficiency. It
seems to me entirely possible that if the greater glaciers
descending from Fairweather Range in earlier times en-
HIGH MOUNTAIN DISTRICT 169
countered the sea soon after reaching the basal plain,
they may have been wasted so rapidly along the line of
contact as to determine there a principal line of morainic
accumulation, and the ramparts of the coast may constitute
the record of a successful resistance by the sea to glacial
invasion.
If this explanation is correct, the Pleistocene submer-
gence of the coast probably extended considerably above
the zone of terraces. The oceanic resistance determining
the deposition of drift would not be effective after the
moraine ridge had been built so high as to become a
partition between ice and water, and the theoretic posi-
tion of the old sea plane is therefore along or above the
highest crests of the moraine.
The hypothetic conditions are similar to those at the
foot of Davidson Glacier. If that glacier should shrink,
and the sea-level should be lowered in Lynn Canal, the
Davidson moraine, if composed wholly of rock débris,
would survive as a crescentic rampart with a flat top;
and if the ramparts of the Fairweather region are strictly
homologous they should have broad and level crests. If,
however, the Davidson moraine is not wholly built of
rock débris, but consists rather of an apron of débris
resting against a concealed ice slope, the resulting ram-
part, when ice and water are withdrawn, would have an
acute crest, with uneven sky-line; but the crest, instead of
representing the plane of the present water-level, would
stand somewhat below it. In viewing the old moraines
of the Fairweather coast I recognized a few local flat |
summits, but the general character of the crest line is
acute and its height is not uniform. If, therefore, the re-
lation of the old glaciers to the sea was like the present
relation of the Davidson Glacier, the sea then stood much
higher against the land than now — or else the land then
stood lower.
170 ALASKA GLACIERS
Whether these old ramparts represent the limit of
Pleistocene ice at the time of maximum glaciation is a
question as to which there may be doubt, but I incline to
the view that the affirmative answer is the true one. So
far as I could judge from distant views, the rounding of
rock ridges and crests, characteristic of flooding by ice,
extends but a moderate distance above the surfaces of
modern glaciers on this part of the coast, and indicates
glaciers of about the same magnitude as are indicated by
the rampart moraines.
On the northwest side of Dry Bay, which receives
Alsek River, a single fragment of a high rampart was
seen, and in association with it a terrace; but thence to
Yakutat Bay the broad foreland is low, its flatness being
relieved only by ridges of moderate height. About Yak-
utat Village and Ocean Cape, at the mouth of Yakutat
Bay, some of these ridges were seen to be morainic,
and it is supposed that the whole foreland is constituted
of glacial waste, chiefly of waterlaid gravel. If high ram-
parts were formed along this portion of the coast they
were afterward destroyed and the material carried sea-
ward by later advances of the ice.
On the mountains near the head of Yakutat Bay are
fragmentary terraces at various heights ranging up to
1,200 or 1,500 feet, but as they face the bay rather than
the ocean, it is entirely possible that they are of glacial
rather than marine origin. Hanging valleys occur on the
eastern wall of Yakutat Bay and on the walls of Russell
and Nunatak fiords. One of these, near Nunatak Fiord,
is now occupied by a glacier which cascades for 1,000
feet down the steep wall of the fiord. The sills of these
valleys range from tide-level to a height of 1,500 feet or
more, and they tell of great erosion by the trunk glaciers.
The associated rounding of topographic angles is carried
higher above surfaces of modern glaciers than in the
HIGH MOUNTAIN DISTRICT I7I
vicinity of Mount Fairweather, and this character seems
naturally related to the gentler declivity of the mountain
front. The enhanced alimentation of Pleistocene glaciers
would tend everywhere to increase their thickness and
their rate of flow, but it is easy to understand that the
greater resistance to flow encountered on a gentle slope
would cause
the thicken- WM CLUE
: Gif SN VG ALN (6g
ing there to | (S85 LL vs Gi Os SD g
FEM 4 ig a
be more nota-
ble than ona
steep slope.
So far as
may be judged
by the gradi-
ents of the
neighboring
Malaspina
. FIG. 81. HANGING VALLEY ON THE SOUTH SIDE OF
Glacier, the
NUNATAK FIORD.
ice flood as-
sociated with the hanging valleys and rounded crests of
the Yakutat region should have extended farther seaward
than the line of the present coast, and it is probable that
the outer morainic deposit is not visible. ‘The submerged
moraine ridges within the bay and across its mouth (page
49) pertain to quite moderate expansions of the Malaspina
Glacier. |
The inference that the sea-level associated with the
moraine ramparts coincided with their highest summits
may be interpreted in terms of land change or sea change.
The local phenomena would be explained by assuming
that the land has risen about 1,500 feet since the building
of the moraines, or by assuming that the sea has subsided
that amount, and it is, of course, possible that there have
been changes of both land and sea, and that the discord-
172 ALASKA GLACIERS
ance of levels represents their sum or difference. While
the question thus raised is not susceptible at present of
a complete answer, it is nevertheless possible to make
some progress in that direction.
In studying the Alexander Archipelago, which adjoins
the Fairweather coast on the southeast, no evidence was
found of a high sea-level in association with the greatest
Pleistocene glaciers; but it seemed probable, on the con-
trary, that the mid-Pleistocene sea-level was considerably
lower than the modern sea-level. Beyond the St. Elias
Mountains, in the opposite direction, lies the district of
Prince William Sound, and the Pleistocene history of that
region appears to resemble closely that of the Alexander
Archipelago. The Pleistocene history of the Fairweather-
St. Elias coast thus appears to be exceptional and to be con-
trasted with the histories of neighboring coasts on both
sides. ‘This contrast is associated with a contrast in gen-
eral geologic history, as revealed in the physiography.
The district of the Alexander Archipelago is genetically
a plateau, from which mountains and valleys have been
developed by erosion. The district about Prince William
Sound has been found by Schrader and Spencer? to have
the same character and history. In each case a region of
complex structure was reduced to a condition of low
peneplain by long-continued erosion and then uplifted
bodily though somewhat unequally. The original altitude
of one plateau ranged from 3,000 to 7,000 feet, that of the
other averaged 6,000 feet. The intervening tract has
been lifted to a much greater height, so that its culminat-
ing peaks have altitudes of 15,000 to 19,000 feet, and it is
probable that crustal deformation here produced mountain
ranges directly, instead of creating a plateau from which
they were developed by erosion.
1 Geology and Mineral Resources of a portion of the Copper River district,
Alaska. U.S. Geol. Survey, pp. 62-76, 1901.
PRINCE WILLIAM SOUND 173
Two facts indicate that these mountains are geologically
young. The first is paleontologic. Russell found, in
one of the lower spurs of Mount St. Elias, a fossil marine
fauna composed wholly of forms which still inhabit the
coastal waters of Alaska.’ These show that the last great
elevation of the mountain range is recent, as measured in
terms of biologic evolution. The other evidence of youth
is found in the great height of the mountains. As pointed
out by Powell, the degradation of mountains is so rapid
that only young mountains can be lofty. The St. Elias
Range is not only lofty but steep, and its rate of waste
must be rapid. The fact that it is lofty despite rapid
waste indicates that its waste is compensated by growth.
In view of the differences in general geologic history,
there need be no surprise if the Pleistocene history of the
district of high mountains should differ from the Pleisto-
cene history of the districts of Alexander Archipelago
and Prince William Sound. In view of the loftiness of
the mountains, it is rather probable than otherwise that
uplift has occurred since the epoch of chief Pleistocene
glaciation. It is therefore inferred with some confidence
that the discordance between the sea-level indicated by
the rampart moraines and the present sea-level has been
brought about chiefly by local uplift of the land.
If this view is correct, the disturbed marine clays ob-
served near La Perouse Glacier (fig.22) may be con-
nected with a fault zone of Pleistocene or post-Pleistocene
date.
PRINCE WILLIAM SOUND
Prince William Sound is a very irregular bay, opening
southward (pl. x1). All about it are mountains, the
higher being massed at the north, and others encroaching
on its area as promontories and islands. The largest islands,
1 National Geographic Mag., vol. 3, pp. 171-172, 1891.
174 ALASKA GLACIERS
Montague and Hinchinbrook, lie at the south, separating
the sound from the open ocean. The inlets of the north-
ern coast, some of which we visited, are fiords, abounding in
evidence of glacial sculpture, and the lower slopes of the as-
FIG. 82. PENINSULA NEAR ORCA, PRINCE WILLIAM SOUND.
Shows the glacial rounding of mountain crests, fifteen miles from the ocean.
sociated peninsulas and islands are well rounded. On the
east side of the sound the rounding extends to an estimated
height of 3,000 feet, in Columbia Bay, at the north, to about
*
FIG. 83. HINCHINBROOK ISLAND, FROM THE SEA.
Shows a serrate crest line, little, if at all, modified by overriding ice.
4,000 feet, and to the same or greater height in Port Wells.
Seaward the height diminishes and the higher crests of
the outer islands are comparatively angular and serrate.
PRINCE WILLIAM SOUND 175
It is probable that Pleistocene ice occupied the whole
sound, but nothing is known of its seaward limit.
In College Fiord, a branch of Port Wells already de-
scribed (page 81), there is a magnificent system of hanging
valleys, the larger being still occupied by glaciers, which
enter the fiord with ice cascades. These side glaciers
have accomplished something in the way of erosion since
the disappearance of the trunk glacier to which they were
once tributary, so that they do not rest upon the un-
modified face of the fiord wall, but occupy shallow chan-
nels. In a general way the surfaces of the glaciers, in
their lower courses, are flush with the adjoining portions
of the fiord wall.
My attention has been directed by Gannett to the fact
that several of the cascading glaciers make two leaps, and
that there is a certain amount of harmony in the spacing
of the falls. When the region shall have been thoroughly
studied it is possible that the interpretation of these corre-
spondences may develop a special chapter in the history
of the ice retreat.
With the aid of a series of photographs made by Mer-
riam, I have computed the approximate heights of the
more important cascades, as follows: Wellesley, 1,700
feet; Vassar, 2,200; Bryn Mawr, (trunk) 1,300, (left
branch) 2,700, (right branch) 2,500; Smith, 1,250, 1,700
Well Vas. BM. Smith Red
FIG. 84. DIAGRAM OF NORTHWEST WALL OF COLLEGE FIORD.
Short horizontal lines show the relative positions of the cascades of Wellesley, Vassar,
Bryn Mawr, Smith and Radcliffe glaciers. S.L. sea-level. Scale, 14,000 feet =1 inch. Com-
pare figures 44 and 45.
and 2,600; Radcliffe, 1,800 and 3,500. When these are
platted to scale in their proper vertical and horizontal re-
lations (fig. 84) they fall into two series, descending south-
ward from the head of the fiord. Making some allowance
176 _ ALASKA GLACIERS
for the greater volume of the side glaciers when the trunk
glacier filled the fiord, I have indicated the profile of the
trunk glacier by a dotted line (as). The inclination of
this line from the horizontal is about 2°, or one in twenty-
five. Its height above tide ranges from 2,800 to 4,800 feet,
and it indicates a thickness of ice exceeding these figures
by the depth of the fiord, whatever that may be. In the
line of Gannett’s suggestion, a second tentative profile
(cp) is drawn in similar relation to the crests of the lower
series of cascades.
The depth of ice indicated by the hanging valleys is
somewhat less than that which would be inferred from
the rounding of projections, and it seems probable that
the epoch during which the hanging valleys received
their principal sculpture was not the epoch of maximum
glaciation.
A cordon of high hanging valleys surrounds Harriman
Fiord. Above Barry, Serpentine and Surprise glaciers
they contain hanging glaciers at a general height of about
4,000 feet, and east of Harriman Glacier their ice banks
coalesce in a continuous terrace along the valley wall (page
95). ‘The surface of the trunk glacier to which they are
adjusted probably lay 5,000 feet above present sea-level.
On the north side of Montague Island and at various
points on the peninsulas of the east and west sides of the
sound, a horizontal terrace was observed, at an estimated
height of 50 to 75 feet above tide. No near view was
obtained, and I did not learn its character.
As the Pleistocene glaciers extended at least to the
outer coast line, as their work of erosion was great, and
as their limit is not indicated by conspicuous moraines, the
provisional inference is made, as in the discussion of the
Alexander Archipelago, that the ocean surface was com-
paratively low at the time of their greatest expansion and
that their outer moraines are now submerged.
KADIAK ISLAND 177
KENAI PENINSULA
My observation of the Kenai Peninsula was restricted
to the northwest side of its more southerly arm. It is
there constituted by a lofty upland partially dissected by
large trenches, some of which now contain glaciers. Its
upper parts have a comparatively mature topography,
and seem to constitute remnants of an ancient pene-
plain, which has been bodily uplifted, with some disturb-
ance of original horizontality. The plateau resulting
from this uplift was deeply trenched along the main lines
of drainage, and the valleys thus opened were modified in
characteristic manner by Pleistocene glaciers. They are
now U-troughs, and some are partly submerged, so as to
constitute fiords. On the side facing Kachemak Bay and
Cook Inlet, it was evident that the old glaciers extended
beyond the position of the modern coast line, but nothing
was seen to indicate their outer limits.
KADIAK ISLAND
Kadiak Island is 100 miles long and 50 miles broad. Its
longer axis, trending northeast, is parallel to the neigh-
boring coast of the Alaska Peninsula, from which the is-
land is separated by Shelikof Strait, 30 miles wide. Afog-
nak Island, a close companion of Kadiak, continues its
northeasterly trend; and the Barren Islands serve as
physiographic stepping stones to connect the group with
the axis of uplift following the oceanic side of Kenai
Peninsula.
The island is mountainous throughout, but contains no
lofty range. As on the Kenai Peninsula, the summits
tend toward uniformity and an even sky-line, and there
are remnants of an ancient uplifted peneplain. Such
lowlands as we saw are of moderate extent and uneven
surface. The coast line is sinuous, and some of the nar-
178 ALASKA GLACIERS
row bays may properly be designated fiords, although
_ less strongly characterized than those of southern Alaska.
Opportunities for personal observation included near
views of the northern coast, a brief landing near the west-
ern extremity, and a longer stay near the eastern extremity,
with Kadiak Harbor as a base of operations.
Our landing at the west was on a part of the coast fa-
cing Shelikof Strait, west of Sturgeon River. The view
was limited by a fog, but I was able to recognize two
narrow U-troughs with simple contours. The ridge be-
tween them, composed of granite rock, was seen to have
a narrow, straight crest; and a parallel ridge, less clearly
revealed, appeared to be of the same character. The
troughs were evidently shaped by glacial ice, and the nar-
rowness of the intervening crest indicates that the chief
work was done by valley glaciers, rather than by an over-
riding ice-sheet.
Thirty miles farther east we entered the mouth of Uyak
Bay, a long inlet heading south of the middle of the island
but opening northward. The mouth lies among hills or
low mountains, whose thorough rounding indicates com-
plete flooding by Pleistocene ice. ‘Toward the interior I
could see mountains, several thousand feet high, whose
blunt summits told of ice-scoring, and beyond them loftier
peaks with angular crests. ‘The slopes bordering the bay
descend steeply to the water, and there is no foreland, but
the sweeping curves characteristic of the typical fiord are
wanting. No accumulations of drift were seen.
Steaming north from Uyak Bay and then eastward, we
passed two large projections of the coast, one a peninsula
(Ugat) and the other an island (Uganuk), and the extrem-
ities of these were thought not to be glaciated. On the
peninsula are hills with ragged summits, apparently crested -
by outcropping igneous dikes.
Straits separate the north end of the island from three
KADIAK ISLAND 179
smaller islands, all mountainous. Traversing the straits,
we found familiar signs of ice work: on Raspberry Island
a straight wall with hanging valleys; on the Kadiak side
a general rounding of all summits up to the clouds, which
hung at about 2,000 or 2,500 feet. Here, too, the water
is bordered in places by a lowland or terrace (fig. 85),
carved, for the most part, from vertical slates. In detail
the lowland is uneven, and it is locally broken into islands,
but its general plane is easily traced and, as already noted
by Dall,* inclines from east to west. The height ranges
from about 100 feet to sea-level.
At the extreme east lies Chiniak Bay, a broad opening,
invaded on one side by mountain promontories, and partly
FIG. 85. TERRACE ON SPRUCE ISLAND, OPPOSITE KADIAK ISLAND.
sheltered from the ocean by a group of low islands. Close
to the islands is the village of Kadiak. The general trend
of promontories and islands is northeast-southwest. The
islands are shredded remnants of a plain carved from ver-
tical slates, probably a base-level plain contemporaneous
with the terraces along the straits (fig. 86). Their uneven
surfaces include rounded hills about 100 feet high, but the
plane of the original peneplain must pass above these.
All surfaces about the bay are glaciated. The island
topography is moutonnée, with a large pattern, individual
bosses being sometimes half a mile or more in length. A
few patches of glacial polish and striz were found, though
such records have been generally obliterated by weather-
1 Seventeenth Ann. Rept. U. S. Geol. Survey, part 1, p. 863, 1896.
ALASKA GLACIERS
ISLANDS OFF KADIAK.
FIG. 86.
The observer stands on a promontory of Kadiak Island at a height of 1,000 feet and looks eastward. At the left is the village of Kadiak, built on a slo-
ping foreland. Islands and foreland are remnants ofa peneplain. See page 179.
ing. The valleys be-
tween promontories
of the mainland are
U-troughs. The steep
hill back of the village,
a mass of slate, is
smoothed and fluted
on a grand scale, its
original topography
being so completely
remodeled that its
drainage seeks new
routes and is engrav-
ing narrow canyons
across the rounded
slopes (fig. 87).
Northwest of this hill
stands a higher ridge,
where the upper limit
of ice-rounding is seen
to be about 3,000 feet
above tide, and where
several hanging val-
leys overlook a finely
sculptured trough (fig.
88). It is evident that
a confluent ice-sheet,
enveloping all but the
highest summits, here
flowed to the north-
east, with a thickness,
along the present coast
line, of 2,000 to 3,000
feet. No important
masses of drift were
seen.
KADIAK ISLAND 181
While these observations cover but a small part of the
island, they are so distributed as to throw considerable
light on Pleis-
tocene con-
ditions. The
glaciation of
the eastern,
northern and
western ex-
tremities of
the island, and
the notable
A
h e i g h t.ta FIG. 87. HILL BEHIND KADIAK VILLAGE.
Showing glacial sculpture and subsequent erosion by a stream.
which ice
sculpture extends at the east and north, indicate a practi-
cally continuous glacial envelope, from which scattered
peaks pro-
jected as
nunataks.
Afognak and
the other im-
portant is-
SN lands of the
= ¥. ih 7 i a group were
2 wr probably in-
NC SSE] cluded in the
4 same envel-
: | ope, and the
“ice extended
in many di-
rections be-
yond the po-
sition of the
present coast line. The apparent absence of glaciation
from salient features of the northwestern coast indicates
FIG. 88. HANGING VALLEY NEAR KADIAK VILLAGE.
The lower ground was shaped by . large glacier moving from left
to right.
182 ALASKA GLACIERS
that the ice-sheet of the island was not an overflow from
the mainland, for mainland ice could not have crossed
the island without burying deeply the whole northwest
coast. And the same interpretation may be given to the
narrow-crested ridge observed between glacial troughs at
the west, for a strong overriding current would have flat-
tened the crest. The relation of land to sea in Pleistocene |
time is not shown, but remnants of a low base-level plain
indicate a pre-Pleistocene period of stability, during which
the attitude of thé land was slightly different from the
present, the eastern side of the island being somewhat
lower than now.
The reasoning tending to show that Pleistocene glacia-
tion was associated with a low sea-level applies to the south
coast of Kadiak with even more force than to the district
of Prince William Sound, for the island, standing forward
beyond the general line of the Alaska coast, is specially
exposed to the influence of the great ocean current.
REGION OF THE GULF COAST
Fragmentary as were our observations in the districts
we have already described, they were still more fragmen-
tary in those touched farther west and north, and the pres-
ent is therefore a convenient point for retrospect and
summary. The district of the Alexander Archipelago,
the district of high mountains, the district of Prince Wil-
liam Sound, Kenai Peninsula, and Kadiak Island, circle
about the Gulf of Alaska. A curved line passing through
them is more than 1,000 miles in length, and its extremities
are goo miles apart.
In the high mountain region the Pleistocene glacial
system seems to have included alpine glaciers similar to
those of the present time but larger; and these united ina
system of piedmont glaciers, or possibly in a confluent
piedmont glacier, which everywhere reached the sea. In
REGION OF THE GULF COAST 183
the other districts the Pleistocene glaciers were confluent,
extended beyond the line of the present coast, and prob-
ably reached the sea, although their limit is undetermined.
In the high mountain region there has been post-glacial
uplift of the mountains, and in connection with that uplift
great moraines, which were probably formed at the water’s
edge, have become part of the land. In the other districts
the apparent absence of similar great moraines is pro-
visionally explained by the hypothesis that the sea surface
then lay lower with reference to the land and that the
subsequent submergence of a portion of the land has con-
cealed the zone of morainic deposit.
Assuming that a change has transpired in the relation
of land and sea since the epoch of maximum glaciation, it
is of interest to inquire whether that change was a sinking
of the land or a rising of the sea. The general theory of
the subject has not yet reached such a condition as to
afford a satisfactory answer, but, on the contrary, is so
unsettled as to find advantage in every local determina-
tion of the nature of the change which may be made on
independent grounds. In the case of the high mountain
district, the geologic recency of orogenic movement is
indicated in other ways, and the post-Pleistocene emerg-
ence of land is therefore referred with confidence to land
change rather than water change. In the other districts
we have no evidence of recent orogenic change, and the
mountains appear to have been produced by the dissec-
tion of broad plateaus. The uplands about the Alexander
Archipelago and Prince William Sound, and those of
Kenai Peninsula and Kadiak Island, all contain traces of
uplifted peneplains, the uplift having occurred so long ago
that the resulting plateaus were profoundly sculptured
before the advent of Pleistocene glaciers. The districts
of the Alexander Archipelago and Kadiak Island are also
characterized by peneplains near present sea-level; and
184 ALASKA GLACIERS
low terraces observed in Prince William Sound are pos-
sibly of the same order. It is, furthermore, probable that
the pre-Pleistocene dissection of each area was continued
in association with a comparatively low base-level. In
view of the large number of common elements, the whole
region, with the exception of the high mountain district,
may be provisionally regarded as a unit in its later geo-
logic history. The uplifted peneplains do not all stand at
the same height, and there are important differences of
altitude within individual plateaus. ‘These local differ-
ences suffice to show that not all changes can be ascribed
to the sea, and make it probable that the plateaus were
created by changes originating within the earth’s crust.
The low peneplains also show minor discordances, and
while these also must be ascribed to crustal movement,
the fact that they are of moderate amount is, on the
whole, indicative of general crustal stability. It is a note-
worthy, and probably significant, fact that the oceanic
base-level of the region, after resting for a long time at
the height indicated by these low peneplains, dropped
below them at the time of the excavation of the fiords
and then returned to approximately the same position. If
this oscillation was an oscillation of the land, it was of the
broad or epeirogenic type, and the association of wide
extent with approximate uniformity of position after the
completion of the cycle is most remarkable. It would
seem probable that so great a general movement of the
earth’s crust would afford opportunity for the relief of
local strains, and thus be accompanied by important
differential movements. On the other hand, sensible uni-
formity for any region of the magnitude here considered
would theoretically be a characteristic of an oscillation
of the sea. The local evidence, therefore, seems to me
more favorable to the hypothesis that the sea was low
during the fluvial and glacial erosion of the fiords and has
UNALASKA ISLAND 185
since risen, than to the hypothesis that the land was then
high and has since subsided.
UNALASKA ISLAND
On two occasions we spent a few hours at Dutch Har-
bor, making short excursions in the immediate neighbor-
hood, and we also sailed along the north coast on a foggy
day. The opportunities for observation thus afforded
were much more limited than those enjoyed by Russell,’
and my notes are chiefly of service as affording verifica-
tion of his description. The north coast, west of Cape
Cheerful, is faced by a high sea cliff which testifies to
rapid aggression by waves. The cliff shows in cross-
section a number of U-shaped valleys, and these, so far as
the fog permitted us to see them, have the simple contours
characteristic of complete adjustment to the conditions of
ice flow. Several of them end hundreds of feet above the
sea, this condition being manifestly due to truncation by
the receding shore cliff. One of them reaches the shore
at tide-level, and the walls of that one seemed to be
sheathed with a layer of drift in which post-glacial rills
and brooklets have cut narrow gashes. The shore cliff
also truncates, at rather high levels, a few V-shaped
gorges, and the association of these with the glacial troughs
gave the impression that the Pleistocene glaciers were of
alpine type and not confluent. As the mountains were
concealed by fog, I was unable to observe the cirques of
which Russell makes mention.
The forms of the hills about Unalaska Bay are not typi-
cally glacial, but, on the other hand, they are not con-
structional (with a single exception), and if products of
atmospheric waste, they are of unusual type. The single
constructional form is a young volcanic cone near Cape
Cheerful. The other hills are also of volcanic rock, but
1 Bull. Geol. Soc. Amer., vol. 1, pp. 138-140, 1890.
186 ALASKA GLACIERS
give little suggestion of the original mountain forms from
which they were derived. They are irregular alike in
their larger and smaller features.
If the forms of land in this part of Unalaska Island were
constructional, the sinuosity of the coast might be ascribed
to irregularities of volcanic eruption; but as they are ero-
sional, the deep embayments between steep-sided points
and islands, and the dearth of plains near sea-level, point
toward a somewhat recent subsidence of the land or rising
of the sea.
Spurr describes a series of terraces near Unalaska Bay,
ranging up to a height of 1,500 feet, ascribes them to
marine action, and infers a gradual rising of the land in late
Pleistocene time.’ He notes also that the village of Iliu-
liuk stands ona spit which is evidently of recent formation
but is shown by its vegetation to be above the reach of
storm waves, and infers that elevation of the land is now
in progress. The last mentioned observation I was able
to verify, but I was not satisfied that any higher terrace I
saw had been formed by the sea.
BERING SEA
The most extreme and contrasted opinions have been
advanced with reference to the Pleistocene condition of
Bering Sea. It has been stated by one high authority*
that the western coast of Alaska, the eastern coast of
Siberia, and various islands of Bering Sea, are all glaciated
in such a way as to indicate the occupation of the eastern
part of the sea by an ice-sheet; and it has been asserted
1Kighteenth Ann. Rept. U. S. Geol. Survey, Part 11, pp. 266-267, 273, 276,
1898.
2John Muir. On the Glaciation of the Arctic and Subarctic Regions visited
by the U. S. S. Corwin in the year 1881. Rept. Cruise of the Corwin, 1881,
Washington, 1885. .
BERING SEA 187
by another high authority’ that there are no evidences of
glaciation, either general or local, on these various coasts
and islands. A third investigator,’ also of high rank,
ascribes the fiords of the Siberian coast to glaciers, but
finds no evidence of glaciation on the neighboring coast
of Alaska about Port Clarence. My own opportunities
for observation were limited to a few hours each on St.
Paul, St. Matthew and Hall islands, a few hours sailing
past the Siberian coast, with a brief landing in Plover Bay,
a distant view of Cape York, a point southeast of Cape
Prince of Wales, and a few hours on the tundra near Port
Clarence. The scanty facts thus gathered can not be
expected to settle the vexed question; but, in view of the
wide diversity of existing opinion, it appears worth while
to make record of even hasty observations and first im-
pressions.
Of St. Paul Island we saw the southern peninsula. The
land is there composed of remnants of volcanic cones
FIG. 89. CRATER RIM ON ST. PAUL ISLAND.
Shows projections which would not survive glaciation. Photograph by U. S. Coast Survey.
whose softened profiles indicate long-continued weather-
ing. The forms are smooth, except where cut by the sea
1W.H. Dall. Bull. 84 U.S. Geol. Survey, p. 258, 1892. Alaska and its Re-
sources, pp. 461-464, 1870.
2A.E. Nordenskiold. The Voyage of the Vega. New York ed., pp. 569,
583-585, 1882.
188 ALASKA GLACIERS
or varied by traveling dunes of lapilli. To my eye they
conveyed no impression of ice sculpture; I saw neither
the long parallel grooves and ridges which glaciers some-
times carve from homogeneous rocks, nor the groups of
moutonnée bosses which they usually develop where rocks
are of varied texture. On the main part of the island are
younger cones with well-preserved craters, and photo-
graphs show that with these are associated crags such as
an overriding glacier would not spare (fig. 89). Neither
is it to be supposed that the craters themselves would
survive the erosive action of a great ice-sheet. It may
be affirmed with confidence that if the island was ever
traversed by a glacier the crater-bearing cones are of
later origin. >
St. Matthew and Hall islands are also volcanic, but
without constructional forms. The period of eruption was
so remote as to give time for the complete subsequent re-
modeling of the surface by weathering and erosion. The
coast shows a succession of cliffs, with rare bays and
spits, and is evidently retreating rapidly before the attack
of the waves. The higher slopes, though sometimes
steep, are in general mature, and well adjusted to the con-
ditions of erosion in a climate which obstructs the flow
of water by clothing all surfaces with a sponge-like mantle
of mossy and herbaceous vegetation. I saw nothing of
the peculiar forms characteristic of glacial sculpture, but
noted, on the contrary, a few blunt pinnacles projecting
from the general surface and exhibiting such ragged de-
tails as one does not find in glaciated regions. Figure go
represents one of these which happened to come within
the field of a photograph.
The ordinary landing at Port Clarence is upon a long
spit, but we visited the mainland also, going ashore at a
point where a gently undulating surface rises within a
few miles to hills several hundred feet high. The rock is
BERING SEA 189
a highly inclined slate, and the shaping of the surface has
been wholly by erosion. Except at the coast, the rocks
are concealed by tundra. This spongy growth obstructs
the flow of water, so
that streams are rare;
but we landed at one
of these rare streams
and had a view of its
valley (fig.91). The
valley is evidently
one of mature de-
velopment, and _ its
profiles are perfectly
adjusted to the associated lines of drainage. The divides
are broadly rounded, but the rounding is that characteristic
of inter-stream summits where the vegetal mat is close,
and is distinctively non-glacial. The bed-rock here has
the same physical character as that in the Kadiak region,
but the topographic aspect is altogether different. About
FIG. 90. UNGLACIATED KNOB ON ST. MATTHEW
ISLAND.
an ee SES ae Sane
Sa: &: ft
FIG. 91. STREAM-GRADED VALLEY NEAR PORT CLARENCE.
Kadiak the hills have moutonnée forms, the hills and hol-
lows have a dominant trend, and the drainage is youthful.
At the Port Clarence locality the topography does not
Igo ALASKA GLACIERS
exhibit a dominant trend and all slopes are fully adjusted
in harmony with the drainage.
The southeastern part of the Siberian peninsula is char-
acterized by low mountains with spurs projecting seaward
as promontories and alternating with fiord-like bays. The
topographic details near the coast fall into three categories:
(1) A system of relatively gentle slopes chiefly occupying
uplands; (2) a system of relatively steep slopes chiefly
exhibited in the walls of the fiords (at points of junction
these are sharply contrasted with the slopes of the first
system); (3) coastal features, especially shore cliffs and
FIG. 92. EAST WALL OF PLOVER BAY, SIBERIA.
The sky-line follows the boundary between the steep fiord wall and the smooth topography
of the upland. A spit projecting from the end of the wave-wrought shore cliff protects the
more distant part of the wall.
spits, the product of wave action under present conditions,
The smoother and older topography is not altogether de-
void of steep slopes, but gives an impression of close ad-
justment between processes of subaerial erosion and the
unequal resistances of rock masses. I saw nothing in its
profiles and contours to indicate glaciation. The newer
and steeper slopes are associated with the troughs con-
taining the bays in such way as to suggest glacial action,
but those that we passed near betrayed no smoothing,
grooving, or other minor feature of glacial abrasion. The
shore walls of Plover Bay are precipitous rock cliffs at top
and consist of talus at base, one phase passing into the
other in a manner suggesting that the original rock pro-
file was somewhat similar to the one brought about by
BERING SEA IgI
partial disintegration. They run straight for long dis-
tances. The chief agencies competent to produce such
features are faulting and glacial sculpture, and in this
case glacial sculpture appears to me the more probable
agent, although subsequent weathering seems to have de-
stroyed those minor details of configuration which one
naturally seeks as confirmatory evidence.
There are two accessory features which lend support to
the hypothesis
of glaciation.
In the far dis-
tance, at the
head of the
bay, we could }
see that its a7
trough is con- F=-
nected with
two or more
land valleys,
andit was evi- F!G-93- HANGING VALLEY ON WALL OF PLOVER BAY.
dent that the Figure 92 gives an oblique view of the same wall.
valley most nearly in the direct line of prolongation is dis-
tinctly U-form in cross-profile and has walls of simple con-
tour. The other feature is a niche, high on the wall of the
fiord, having the form of a cirque or hanging valley (fig. 93).
In this case I attach little weight to the testimony of the
hanging valley, because it has no companion on the long
line of cliffs, and therefore may possibly be a simulative
form, determined by local peculiarities of rock texture;
but the distant valley is distinctively glacial in habit.
It seems to me onthe whole probable that the fiords
of this coast contained Pleistocene glaciers of large size,
which extended farther seaward than the general line of
the present coast, but that the spaces between the fiords
were not covered by ice.
192 ALASKA GLACIERS
My observations on the coasts of Bering Sea may be
summed in the statement that Plover Bay and neighbor-
ing Siberian fiords have features indicating local glaciers
of considerable magnitude, that evidence of glaciation was
seen at no other points, and that certain crags and pin-
nacles on St. Matthew and St. Paul islands seemed incon-
sistent with the theory of a continental glacier in the
Bering Sea region. My interpretations at the north agree
substantially with those of Nordenskiold; at the south
with those of Russell.
So far as the Port Clarence region is concerned, what
I have said above has become ancient history before reach-
ing the press. A delay of four years between observation
and publication is fatal to novelty, if one’s theme concerns
a region developing under the stimulus of the discovery
of gold. Near where we landed on the shore of Port
Clarence the town of Bering now stands, and all Seward
Peninsula has been explored by the prospector. To aid
him the U. S. Geological Survey has sent active parties
of geologists and topographers; and as the proof sheets
of these pages pass through my hands, I am able to
examine contour maps of a large part of the peninsula,
and study three comprehensive reports of geologic recon-
naissance. ‘These reports are by Brooks, Mendenhall and
Collier, and tell of explorations and surveys made in the
seasons of 1900 and 1go1.’
They cover the general question of Pleistocene glacia-
tion in a demonstrative and altogether satisfactory way.
The Kigluaik Mountains, between Port Clarence and
Cape Nome— mountains with an extreme height of about
1A Reconnaissance of the Cape Nome and adjacent Gold Fields of Seward
Peninsula, Alaska, in 1900. By Alfred Hulse Brooks. 1901. See pp. 42-53.
A Reconnaissance in the Norton Bay Region, Alaska, in 1900. By Walter
Curran Mendenhall. 1901. See p. 208.
A Reconnaissance of the Northwestern Portion of the Seward Peninsula,
Alaska. By Arthur J. Collier. In press. See pp. 24-29 and 34-42.
SEWARD PENINSULA 193
4,700 feet — nourished in Pleistocene time local glaciers
of some magnitude. These are attested by U-troughs,
cirques, moraines, and moraine lakes. One of them
passed southwestward beyond the foothills of the range,
and may have reached the sea. Another approached or
reached sea-level at the north. The Bendeleben Moun-
tains, farther inland, also contained glaciers, but too small
to push beyond the foothills. Among the York Moun-
tains, which stand between Port Clarence and Cape
Prince of Wales, and have an extreme height of about
2,900 feet, were probably small glaciers, but, if so, they
were wholly contained in the mountain valleys. Except
for these local developments, the surveyed parts of
Seward Peninsula—namely, the southern and western
parts— were not occupied by Pleistocene ice. Over
large areas the mantle of residuary waste lies undisturbed
on the rock from which it was derived; and in these areas
are angular and slender crags, as well as perched boulders
of disintegration, lying in their original positions. Other
large areas bear rolled gravels, associated with a series
of marine terraces.
One of the marine terraces described by Collier and
Brooks was seen by us along the southern base of York
Mountains. It is there a conspicuous bench, ending sea-
ward in a steep bluff, and has a height of about 600 feet.
According to Collier, its uplift has been unequal, so that
the old marine plane is now a warped surface. The fact
of warping also accords with my observation, for such
parts of the neighboring Siberian coast as I was able to
study from the ship seemed altogether free from marine
terracing.
An observation of progressive modern change of level
was made on St. Matthew Island. A small bay on the
east shore, near Glory of Russia Cape, has been cut off
from the sea by a series of shore bars. After the first bar
194 ALASKA GLACIERS
or spit was completed, another was built outside it, and so
on to the number of six or more. The one next the sea
has a crest considerably above high-tide, at the extreme
limit reached by storm waves, and the top of it is covered
by drift-wood, to which annual additions are doubtless
made. The next bar, lying back of this and parallel to
it, is six feet lower. It also is covered by drift-wood, but
the wood is decayed, so that no sound logs were found.
Two others are successively lower and have no drift-
wood, and the innermost are so low as to be covered by
the water of the bay. It is evident that each of these
ridges of shingle was formed bystorm waves at the shore,
and we may assume that its crest height was originally as
far above high-tide as the crest of the outer ridge is now.
The existing differences in height have resulted from the
gradual sinking of the land, and a rude indication of the
rate of sinking is given by the drift-wood. The inner
ridges were made so long ago that the drift-wood they
originally bore has rotted away and disappeared. The
age of the second ridge has given time for only the partial
decay of the timber upon it, and the inference is that the
island has sunk to the extent of six feet in a period less than
that necessary for the complete destruction of logs through
the processes of decay.
CHAPTER III
GENERAL CONSIDERATIONS AS TO GLACIERS
SoME of the field observations recorded in the preced-
ing chapters have more than local interest in that they
open theoretic questions and lead to suggestions bearing
on the general subject of glaciers and their work. Certain
of the suggestions have already been noted, as they seemed
to belong to the discussion of the associated observations,
but others may more appropriately be considered by them-
selves and have been reserved for the present chapter.
The general considerations already set forth refer to an
annual cycle in the distal extent of tidal glaciers (p. 22),
the production of features of shore topography by waves
generated by the calving of icebergs (p. 69), anomalies in
the variations of glaciers (p. 106), the origin of pitted
plains (p. 54), and the origin and interpretation of hanging
valleys (p. 114). The considerations to be presented in
the following paragraphs pertain (1) to the broader char-
acters of the surface of a glacier, (2) to the conditions af-
fecting types of glacial sculpture, (3) to the conditions
(195)
196 ALASKA GLACIERS
of wear below sea-level, and (4) to the parallelism of gla-
ciers and rivers.
THE SURFACE OF A GLACIER
Evenness as Compared to Rock Floor.— The parts of
glaciers which came under my observation were the lower
or distal portions, with surfaces usually less than 1,000
feet above sea-level. In these lower parts the master
characters of the surface are a forward slope in the direc-
tion of flow and horizontality in the direction normal to
the flow, the direction of flow being inferred from the
courses of medial moraines.
The configuration of the rock floors beneath the glaciers
could not be directly observed, but it was possible to infer
their general characters, with high probability, from what
could be seen of the rock floors in front of the glaciers.
Such rock floors are in all cases abandoned glacier beds,
having been covered by the ice not only in Pleistocene
times but, in many instances, in historic time also. As
a rule these bared portions of the glacier troughs exhibit
much irregularity. The fiords vary rapidly in depth; in
places they are diversified by islands. ‘The land troughs
have hills and hollows; and other hills jut through the
glaciers as nunataks. It is therefore believed that the
bottoms of the glacier channels have in general consider-
able inequalities.
These irregularities are only slightly represented in the
configuration of the glacier surface. The greater inequali-
ties of the longitudinal profile of the bed are shown by
cascades of the glacier, but inequalities of the cross-pro-
file are rarely indicated by visible shapes of the ice, and
bosses or hills hundreds (perhaps thousands) of feet high
may fail to influence the surface. If the summit of a boss
approaches the surface it produces crevasses, but the
broader features of the surface contours are not changed.
THE SURFACE OF A GLACIER 197
This leveling of the surface is of course ultimately
caused by gravity, and it is immediately brought about by
variations in the flow of the ice, the directions and veloci-
ties of the flow of different parts being so modified as to
permit the ice to pass around and over obstructions with-
out lifting the glacier bodily. The existence of internal
variations in direction, being attested by the arrangement
of striz on lands that have been glaciated, is a well-recog-
nized fact, but variations of direction alone are not sufhfi-
cient to explain the coexistence of an approximately even
glacier surface with a very uneven glacier bed. The con-
dition of continuity can not be satisfied without variations
of velocity also within the mass. The adjustment of an
ice stream to an irregular channel through the formation
of differential currents is thus quite analogous to the ad-
justment observed in water streams, although the greater
viscosity of the ice may be assumed to prevent the occur-
rence of reversed currents or eddies.
Another factor in the leveling of the ice surface is prob-
ably connected with ablation, or the process of wasting by
melting and evaporation. Portions of the Muir and Hugh
Miller glaciers which were demonstrably stagnant, never-
theless exhibited to the general view a conspicuous even-
ness, and the same remark applies to glacier remnants
stranded, like Reid’s ‘ Dying Glacier,’ on saddles, or trough
summits. These motionless and wasting ice bodies,
though not tabular but curved downward toward their
edges, were bounded by simple symmetric contours, in-
dicative of equable reduction by the wasting agents and a
general interdependence of process for the whole surface.
Lateral Cliff.— Coexistent with the general tendency
toward evenness are several kinds of unevenness, each
determined by some evident special condition. Wherever
the side of an ice stream was observed adjacent to a rock
wall, it was found to present a cliff toward the rock, the
198 ALASKA GLACIERS
ice cliff and rock wall constituting the sides of a narrow
valley or fosse, usually 50 to 100 feet deep. A stream of
water sometimes followed the valley. This feature, fa-
miliar in all glacier districts, has been explained as due to
the heat acquired by the rock through insolation and then
conveyed by radiation to the adjacent ice; and the stream
of water, when present, would help to account for the
valley, for so much of its volume as came from the sun-
heated rock would be warmer than the water of ablation
and have some power to melt ice.
Crevasse Cycle.— Wherever the work of the sun is not
complicated by the presence of rock débris, the inequali-
ties initiated by crevassing are carried by ablation through
a regular cycle of change, ending in their complete re-
3
na
Sh
fe!
eee BSS ty
Rhee. yi mis
* +m. ra «
at Ps Nu, Ee fer
“ec ny OPA
Fag ag
. 4 cea
ee
1800,
FIG. 94. DOWNWARD LIMIT OF CREVASSES IN MUIR GLACIER.
The lower part of the ice is undivided; the upper is split into slabs and columns. The
dark hill in foreground is of ice with a cover of gravel, a remnant of the retreating glacier.
moval. In the crevassing which begins abruptly at the
head of a cascade, the cracks divide the ice into flat-
topped, elongated blocks, usually tapering toward the ends
and more or less connected at the surface by slender
masses analogous to the slivers of half-broken timber.
Whatever the distance downward to which the cracks may
originally extend, the resulting permanent crevasses have
CREVASSE CYCLE 199
only moderate depth, the ice being welded into a practi-
cally continuous mass beneath. Wherever a crevassed
tract was exhibited in section in a tidal cliff, the crevasses
were seen to terminate uniformly along a definite zone,
which was usually nearer the top of the cliff than its base.
The depth of this zone was estimated in different instances
at from 50 to 125 feet, but this did not represent the full
original depth of the crevasses, as something had in every
case been lost by ablation (fig. 94).
AAs soon as the cracks are opened, melting begins on
FIG. 95. CREVASSES AND SERACS, MUIR GLACIER.
their faces, the rate being greatest above, and the flat
tops of the ice blocks, the sevacs of alpinists (fig. 95), are
converted into roof-like crests and pinnacles. In this
condition the surface is nearly or quite impassable (fig.
96). With continuance of ablation the height of the
seracs is reduced, their slopes become less steep, and
many connecting cross ridges become available to the
wayfarer, so that with the exercise of care and patience
one can make his way safely in any direction. Figure
97 shows a characteristic field of this sort, crossed by
some of our party on their way to the great nunatak of the
Columbia Glacier. A continuance of the same reduction
by ablation eventually obliterates the ice waves alto-
200 ALASKA GLACIERS
gether, leaving a plain surface over which progress is
absolutely unimpeded (fig. 98).
FIG. 96. PINNACLES ON COLUMBIA GLACIER.
Thus the cycle of ice degradation by ablation is strictly
analogous to
the cycle of
land degrada-
EZ ig tion by erosion;
Ziggy YL LZL SE an original
plain is rapidly
=
Liye eine ‘
‘Up == —-.-> converted into
=
$56 a region of
highly acci-
dented topog-
raphy, which
slowly returns
to the plain condition through the removal of its promi-
nences. If the cycle is interrupted by the formation
of a new system of crevasses, the analogy still holds,
FIG. 97. BACK OF COLUMBIA GLACIER.
Illustrating gradual smoothing of surface.
CREVASSE CYCLE 201
for the features of the new cycle thus instituted at first
combine with those of the old and eventually supplant
them.
As my excursions on glaciers were all short, it hap-
pened that I never saw a
complete illustration of the
ablation cycle on one gla-
cier, but such examples
should be readily discover-
able. Where the even bed
of a glacier increases its
grade, where it is interrupted PEPER
by a step, producing a CaSs- The rock retards the melting of the ice on
ca de, or where the overrid- which it rests, and thus preserves a pedestal.
ing of a submerged peak produces breaking strains in the
upper part of the ice stream, the smooth ice plain above,
the prismoidal
blocks, the acute
peaks, the gradually
subsiding waves, and
the final ice plain
FIG. 98. LEVEL TRACT ON MUIR
Wann.
Het! ero
SHEET Tsp gay
FIG. 99. IDEAL PROFILE AND SECTION should appear in reg-
ws Ns abate 9 ular sequence, sub-
Illustrating the formation and obliteration of crevasses ‘ =
re stantially as repre
sented in figure gg.
An exceptional condition was observed on the tongue of
the Columbia Glacier which flows into the western embay-
ment of its valley. A plain surface was there interrupted
by an extensive plexus of crevasses, which were filled to
the brim with water and snow (fig. 100). The normal
cycle appeared to be varied in this case by a lack of
drainage, surface ablation progressing only where the air
had access, and truncating the seracs down to the water-
line. It is conceivable that under such conditions a set
of crevasses originating from horizontal stresses may pro-
202 ALASKA GLACIERS
duce no crests and pinnacles, but remain as mere inter-
ruptions of a general plain surface until obliterated by
progressive ablation.
This exceptional condition draws attention to the fact
that crevasse systems are normally underdrained. Look-
ing into crevasses on a warm day,
one may sometimes see the water
of ablation in slender rills disap-
—'} pearing down tunnels or shafts in
FIG. 100. IDEAL sEcTion or the compact blue ice below — to
WATER-FILLED CREVABSES AND. he pathered Goubtiess in eapiacia:
TRUNCATED SERACS. *
or subglacial streams, and eventu-
ally escape at the end of the glacier.
Where the ice carries a heavy back-load of drift the
normal crevasse cycle is greatly modified (fig. 101) and
its completion indefinitely postponed.
: ‘ : Ly nt
As already mentioned in connection , Hara yer
with the Hidden Glacier, the drift |§J7ict light at
é cee pi et
falls into the crevasses and gathers at ‘= -
their bottoms. As the intervening
. rit = Fj
ice blocks acquire acute crests the 5 Vi nat eh Ti
: ; aye! { x ae va ity
greater part of the drift rolls and ra sr ilet Ae
slides from them, and they retain only
enough to darken the surface. Under
the familiar law that a sprinkling or
thin cover of drift promotes melting,
while a heavy mantle retards it, the
pinnacles are rapidly reduced, and "% 10%: “SeLuRNS
h . : ll d d OF DRIFT ON SURFACE
their sites are eventually depressed ....,,cven ov Gian
below the dritt masses accumulated _ Crevasses formed in drift-
z ae Ke F covered ice (a) accumulate the
inthe crevasses. The original asperi- arift (2), and eventually be-
ties made by the crevasses have now °™* ‘Re Sites of Bilis (¢).
been destroyed, but a secondary system has been evolved,
which tends in similar manner to produce a tertiary sys-
tem, and so on indefinitely. Wherever we found a broad
GLACIAL SCULPTURE 203
tract of ice heavily loaded with drift, its surface was made
up of hummocks and hollows, varied here and there by
cliffs of black ice, down which pebbles and boulders oc-
casionally rolled in shifting their position from hill to
hollow. These irregularities, involving, as they do, in-
equality in the distribution of the drift on the surface of
the ice, help to account for the irregularity observed in
terminal moraines.
GLACIAL SCULPTURE
The work of rock sculpture accomplished by the middle
and lower parts of a glacier is performed chiefly by the pro-
cesses of abrasion and plucking. Inabrasion, fragments of
rock held in the under part of the ice, being dragged over
the fixed rock of the glacier bed, file away and reduce it.
In plucking, blocks of bed-rock, being partly surrounded
by the ice, are forced from their bearings and rolled or
slidden forward. If the plucked blocks have originally
stood as projections, they may be broken away, even if
quite firm and flawless; otherwise it is probable that they
can be removed only if originally separated by joints or
other structural partings. The waste resulting from abra-
sion is clay and sand; plucking yields boulders.
One of the chief factors on which the rate of abrasion
depends is the velocity of the moving ice. If the bed-
rock surface is uneven, the ice does not flow over all parts
of it at the same rate, but moves slower in the hollows
and faster across the prominences. This difference results
partly from the condition of continuity, which demands
higher average speed where the cross-section is less, and
partly from the tendency of parts embayed in hollows to
lag behind the general mass. The prominences are there-
fore abraded more rapidly than the adjacent hollows, and
the profile is thus reduced to simple forms.
Another factor on which rate of abrasion depends is
204 ALASKA GLACIERS
pressure; the abrasion is more rapid as the pressure of the
glacier against the bed-rock is greater." The resistance
which the moving ice, through its viscosity,? opposes to
change of form, causes it to press unequally on different
parts of an uneven bed, and to abrade most rapidly those
parts whose prominence compels the ice to change its
direction. Thus in a second way there is a tendency to
reduce the profile of the bed to simple forms.
The amount of resistance developed by viscosity de-
pends on the rate of deformation; more force is necessary
to deflect the ice quickly than to deflect it slowly. The
parts of the bed which cause the most abrupt turns are
therefore subjected to greatest pressure and to greatest
wear, with the result that the profiles of the bed eventually
become curves of large radius, adjusted to slow bending
of the moving ice.
If the general motion of the ice is very slow, the resist-
ance developed by viscosity is small and the resulting
sculpture curves have comparatively small radius. If the
ice moves rapidly, the sculpture curves have large radius.
1There are two theoretic limits to the law that abrasion increases with pres-
sure. It has been argued by N.S. Shaler that because the melting temperature of
ice is lowered by pressure, the basal part of a thick glacier must consist of water
instead of ice (Outlines of the Earth’s History, pages 237-239, 1898); and such
‘pressure-molten’ water would manifestly be powerless to grind rock waste
against the rock bed. G. F. Becker has suggested to me in conversation that
where the pressure is great there also the elastic limit of the ice is far exceeded
and the ice should be expected to flow about rock fragments so as to incorporate
them in the glacier and reduce or destroy their effectiveness as tools of abrasion.
These considerations are not included in the above analysis because, while I do
not see my way to their satisfactory discussion, I fail to perceive that they help
to explain the phenomena of ice erosion as seen in Alaska. Whatever their in-
fluence may be, it has not prevented exceptionally great erosion in places where
the Pleistocene ice was exceptionally deep.
2In untechnical usage the word véscostty is ambiguous, being applied to a
property of liquids opposed to mobility and to a property of solids opposed to
rigidity. In the present paper it has the technical meaning given by the physi-
cist, and is the property of fluids and solids in virtue of which internal dif-
ferential movement, or shear, consumes time. The greater the viscosity the
slower the yielding to a given shearing force.
te
= _ a j
Se ey Oe lL oF
.
GLACIAL SCULPTURE 205
The tendency toward curves of large radius is more effect-
ive where the material of the bed is easily worn than
where it is obdurate.
A third factor affecting rate of abrasion is the material
abraded. Some materials yield more easily than others
and are worn more rapidly. Where the material of the
glacier bed is heterogeneous, including both yielding and
obdurate rocks, there is a tendency to hollow out the
yielding rocks and leave the obdurate masses prominent.
This tendency is opposed by those arising from the vis-
cosity of the ice, and the type of the resulting sculpture
in each individual case is a compromise. It is thought
that the relative importance of viscosity is greater with
swift-moving ice than with slow-moving ice.
A fourth factor is found in the quality and quantity of
the abrasive material, the rock particles set in the base
of the ice. The particles picked up from shale would not
be effective in grinding quartzite, but particles from
quartzite would act vigorously on most other rocks. The
abrasive action of pure ice is probably nil. The influence
of this factor is not easily formulated, but there can be no
question that it qualifies the influence of other factors in
important ways.
The sculpture wrought by plucking differs notably
from that due to abrasion. The plucking of a block of
rock removes a projection and leaves a hollow. A sur-
face which has been reduced chiefly by plucking abounds
in salient and reentrant angles, and would be called
hackly if its pattern were smaller. Usually its salients,
and often its reentrants, are rounded by subsequent abra-
sion, producing a topography to which Saussure’s title of
moutonnée is peculiarly applicable.
The conditions which locally determine plucking rather
than abrasion are not clear to me. Evidence of plucking
is seen more frequently on hard rocks than on soft. The
206 ALASKA GLACIERS
clearest examples are on salient masses, but this may be
merely a question of exposure, for the finest illustrations
of abrasive sculpture are also onsalients. Where a heter-
ogeneous rock bed acquires an uneven surface by abrasion,
the prominences of obdurate rock would be specially ex-
posed to plucking, and it is easy to understand that pluck-
ing may be combined with abrasion in the reduction of
such a tract.
The unevenness produced by plucking is a minor feature
of the sculpture topography. When greater features are
considered it is evident that plucking as well as abrasion
is more active on salient than on reentrant profiles, for how-
ever hackly an ice-worn hill may be in detail, its general
profile and contours have the same sweeping curves which
characterize the products of abrasion.
The preceding discussion, which for brevity has been
given somewhat deductive form, is largely based on field
observation, being the result of an endeavor to understand
the varied phenomena of sculpture observed in Alaska.
In a region where the evidence of great glacial erosion is
overwhelming, where multitudinous hanging valleys, the
general obliteration of spurs from the sides of U-valleys,
and the dominant and thorough rounding of crests and
corners of hills and small mountains, testify to an enor-
mous amount of glacial degradation, it was a matter of
surprise to find the reduction of the surface to smooth-
sweeping curves a somewhat rare phenomenon. By far
the greater number of well-exposed glaciated areas, even
where the degradation has been profound, abound in low
embossments and in more or less angular groins or re-
entrant spaces showing little trace of abrasive action.
These surface characters presented themselves as facts
requiring explanation; and I have come to regard them
as indications of the great importance of plucking in the
work of glacial erosion.
re =
‘on
fi
PLATE Avil
“Vevwe
sortonimorg atow-99i 18 eworle bavorgst0t afT seg. 5 ee
aij] .toioslD miC1 odd to dioe jeuy polls V tiuM to [lew sano ont to
ta S20 © ze. asd ai spusiole el bia msse-qu oft mont boewsiv
rts EP ome re aes
’ : > ota / ee ee ne A
ee |S
> ae
Mk age
(
LS are
ul
4 +
Y=" sh
PotuaTe
E
=.
er j
7
‘*
sy oe
Ss
<a:
”%
‘&
wees eile are on salient sismalll, bait this may
mere! question of exposure, for the finest iliustrat io s
of sbemaisil sculptixe dre also on salients. Where a oe . . |
ceneous rock bed acquires an uneven surface by abr:
the prominences of obdurate rock would be specially e :
posed to plucking, and it is easy | to understand that pluc we :
ing may be combined with. abrasion. in the ‘Feduction(
such @ tract :
The “ARERR HON OR DY
of the sculpture topography.
ie picvinete | 6 -Guactarep Rocks ~ as well as ab
Upper Figure.—A portion of the'east wall of the valley son sin
i ie Rater sare Pas. 899.
and were probably pias tie century ago The dretion ae
movement was from left to 207...
yy) : fy
The pes of re Gat : tbe as Sretes iby a: rap
bert, uit SOPRESY oy ae ESS SS fb ited States Geo
Surveyose rvation, berg the reat of ape
Lower Figure. —The foreground welsieandiiaedhia
of the gaat mee of Muir Valley, just south pe PD omega |
views i tae ced yea cetry t
was probably cove tury ago
The eine vane ioe |
of hw peg an i at i : alee #ué : ° avian itp sh 2 ferdene “Sa er
Photographed by G. June: Negative sai
United ranaerbibiibe der de mist it was. a waatter @
surprise to find the reduction of the surface to smootm
sweeping curves a soméwhat rare phenomenon, Bye
the greater number of well-exposed glaciated areas, eam
where the degradation has been profound, abound im ia™
emihossments and in more. or less angular groins ora
entrant spaces showing little trace .of. abrasive th .
hewe surface characters presented themselves as i “a
ping explanation; and I have come to regard Gy
fieaifons of the great importance of plucking i int
& <i aiaeantt erosion,
ae
H, A. E. VOL, Ill PLATE XVIiil
ee
ve
da le ln ig
GLACIATED ROCKS
HELIOTYPE CO., BOSTON.
GLACIAL SCULPTURE 207
The importance of plucking may also be inferred, as in
fact it has been by Dana, from the abundance of boulders
in the moraines of an ice-sheet. In the waste deposited
by an alpine glacier it is not easy to discriminate
plucked boulders from the boulders which have fallen to
the ice from adjacent rock slopes and been carried for-
ward as back-load, but the waste carried to the edge of a
great ice-sheet like the Laurentide has all been picked
up as well as transported by the ice. <A portion of such
a body of waste must be referred to the mantle of resid-
uary and alluvial débris found initially on the land by the
expanding ice mass, and this portion of course includes a
contingent of boulders; but there is no reason to regard
this factor as of great importance. It is probably much
more than offset by the destruction of boulders in the
glacial mill, for in the making of the rock flour which
constitutes the body of glacial till, the abrasion of the
coarser waste carried by the bottom ice may approach,
or even exceed, the abrasion of the rock floor. While
these various factors do not admit of definite valuation, I
think it fair to say that the ratio of boulders, on the one
hand, to clay and sand, on the other, in the waste deposits
as a whole, is something less than the ratio of plucking
to abrasion in the erosive work of such an ice-sheet as
the Laurentide. |
The study of this subject made such slow progress in
the field that opportunities for good photographic illustra-
tion were not improved. The views reproduced in plate
XVIII were taken to show abrasive work, and illustrate
plucking only incidentally. ‘The upper view looks up the
wall of Muir Inlet. It shows stratified rock, with a boss
of more massive, possibly plutonic, rock beyond. A
century ago all the stratified rock was covered by Muir
Glacier. At the left near the sky-line the strata are seen
to be obliquely truncated, and the plane or nappe of trun-
208 ALASKA GLACIERS >
cation can be traced across the view. It really includes
the foreground, at least down to the mantle of moraine;
and it is part of the wall of the glacier trough, wrought by
the ice into curves of large radius. But the detail of this
erosion plane, shown in the center of the field, is distinctly
hackly, as though (and probably because) the degrada-
tion of the stratified rock was accomplished largely by the
breaking away of blocks. The prominent angles and
edges of strata are abraded and highly polished on their
stoss sides, but their lee facets are unworn.
The lower view shows the stoss side of a granite knob,
also near Muir Glacier. Here the indications of abrasion
are most conspicuous, but a groin crossing the foreground,
and a niche at the right, are probably remnants of scars
made by plucking.
The rock areas best showing the character of the sculp-
ture due to plucking are in the barren regions about the
glaciers, and these were often included in our views of
glaciers; but the photographic methods employed to show
details of the white ice do not secure the details of dark
rocks. The peculiar embossment topography is merely
suggested in some cases by the pattern which results from
the preservation of snow in concavities of the surface.
See the mountain spur beyond Reid Glacier in figure 14
and the hill at the left of Hugh Miller Glacier in plate m1.
Similar patterns appear on both sides of Serpentine Glacier,
in the photogravure at page 124 of volume I.
Figure 102 contrasts several types of sculpture. A tract
bordering the water of the fiord at the right shows elab-
orate fluting on a grand scale, the abrasive work of a
powerful, and doubtless fast-moving, ice stream, flowing
from left to right through the fiord. The material here
sculptured is argillaceous slate, similar to that at Kadiak
(figs. 86 and 87). The spurs beyond are partly of more
obdurate material, including schists and granitoid rocks;
GLACIAL SCULPTURE 209
they were sculptured chiefly by currents approaching the
fiord from the right; and plucking was an important fac-
tor of the process. The peaks against the sky were above
the Pleistocene ice.
In the last example the unevenness in the region of
extensive plucking is partly due to the varying resistance
of heterogeneous bed-rock. This factor finds strong ex-
pression in the forelands and low islets at New Metlakatla,
Sitka, and Kadiak, where peneplains well reduced toward
base-level, and therefore
presumptively of nearly
even surface, were much
roughened by a moderate
amount of glacial deg-
radation (see figs. 64, 65
and 86, and pl. xvi). =e"
It is also strongly ex- ~
pressed on the slopes of
Unalaska Island about
Unalaska Bay. There is
a general lumpiness of
the surface which would hao ail ONS
throw doubt on the |i : it ones ua 2S Zs
theory of extensive Pleis- Ae sai i. i
tocene glaciation were
the theory not strongly
supported by the con-
spicuous glacial sculp-
ture of other parts of the
island. Except where
exposed in sea cliffs, the rocks are largely covered by a
tundra mat, and this leaves room for doubt as to the steeper
slopes, where many of the knobs may be landslips; but on
the gentler slopes the knobs are clearly obdurate elements
of the heterogeneous volcanic mass, rendered prominent by
WLAN 7,
ivy Jf M { i a
| h
Y Wy Y Wy
FIG. 102. ICE SCULPTURE IN RUSSELL FIORD.
210 ALASKA GLACIERS
differential erosion. A strip of lowland between Dutch
Harbor and Iliuliuk is so hummocky and so set with lake-
lets as to remind one of a terminal moraine of the Lauren-
tide ice-sheet, and I half expected to find it a heap of glacial
waste; but every discovered break in its turfy-mantle
revealed volcanic rocks zz stu, and I was forced to regard
its undulations as products of sculpture.
PRESSURE AND EROSIVE POWER OF TIDAL GLACIERS
The discussion, in the last chapter, of the fiords of the
Alexander Archipelago assumes (page 163) that a tidal
glacier is partly supported by the sea, so that the full
weight of the ice does not press on the rock floor, and
the glacier’s power to erode is correspondingly diminished.
This assumption has been often made, and is usually given
quantitative form. The sea is said to sustain a portion of
the glacier equal in weight to the body of water displaced
a by the ice, and correspondingly to dimin-
ish the pressure of the glacier on its bed.
WELLE When the subject is approached in a
certain way this view seems altogether
plausible. In figure 103, @ represents in
“iusilidméa Section a sea 2,000 feet deep with a flat
== | bottom. In the sea floats an iceberg of
which the sides are vertical and the top
- and bottom are horizontal planes. Its
one thickness is 1,600 feet, and the submerged
part measures 1,400 feet, the densities of
the ice and the water having the ratio of
FIG. 103. DIAGRAMS 3 ‘
mivermatina vio. 7 108. The water sustams theooim
TATION THEORY OF weight of the ice. Now conceive the
Bapak GRACES: water of the sea to be drained away.
The block of ice sinks to the bottom (4) and is wholly
supported by it. Again, conceive the water of the sea to
be only partly withdrawn, the depth being reduced from
|
|
]
|
|
|
|
He
l
|
|
|
N
'
% VMdddiM bi UddiMdlddddee
PRESSURE OF TIDAL GLACIERS 211
2,000 feet to 1,400 feet (c). This is equivalent, so far as
the block of ice is concerned, to raising the sea bottom
from its position in @ until it touches the base of the ice-
berg. The ice is not lifted by the sea bottom; it still pro-
jects into the air just 200 feet; it is still supported by the
water, and though touching the sea bottom does not press
on it. Finally, conceive the water drawn down until its
depth is but 7oo feet (d). This depth of water is just
able to float a berg 800 feet thick. Therefore 800 feet of
ice, or one-half the thickness of the block, are now sup-
ported by the water, and the remaining 800 feet by the
sea bottom.
Let us now approach the subject in a different way.
Begin with a block of ice of the same dimensions as be-
fore, resting on a horizontal bed, with which it is every-
where in contact (fig. 104,@). The pressure on each square
inch of the bed equals the weight of the
column of ice above it—about 640
pounds. Now introduce sea water about
the ice until it has a depth of, say, 700
feet (4). The water presses horizontally
against the vertical faces (as indicated by
the arrows), but, as there is no vertical ric. 104. pracrams
component to a horizontal force, the water 'tUSTRATING NoN-
+ . ° FLOTATION THEORY
pressure neither lifts the ice block nor 4. rar ctactes.
pushes it down. The block continues
to rest on the bed, exerting still a downward pressure of
640 pounds per square inch of base. ‘This line of reason-
ing seems quite as plausible as the other, but the result
is different.
A little consideration discovers the cause of the dis-
crepancy. In the first analysis it is tacitly assumed that
the water exerts its pressure not only on the sides of the
ice block but on its base, and this whether the block floats
free or touches the sea bed. In the second analysis it is
212 ALASKA GLACIERS
tacitly assumed that the contact of the ice with the bed
excludes the water. In order to determine which analy-
sis is applicable to the case of the tidal glacier, it is neces-
sary to consider whether the nature of the contact between
the glacier and its bed is or is not such as to exclude the
sea water and its pressure.
It was suggested by my colleague G. F. Becker that a
laboratory test might be applied to one of the principles
appealed to in the second of the two analyses — the prin-
ciple that a solid rectangular block immersed in a liquid
is not buoyed up by the liquid provided its base is in com-
plete contact with the bed on which the liquid rests; and
at his request two pertinent experiments were made by
A. L. Day in the physical laboratory of the U. S. Geolog-
ical Survey. In the first experiment a small slab of plate
glass was cemented to the bottom of a glass vessel (fig.
105 ), for the purpose of giving an accurately plane surface,
and the vessel was then partly filled
with mercury. A second piece of
Z plate glass was immersed in the
_-=Z mercury and pushed down until
{ii + one of its faces came into contact
Fic. 105. conracr ramxom- With the face of the fixed slab. Ag
ENA OF GLASS AND MER- the density of mercury is about five
CURY. °
A block of glass rests ‘on ihe bot- times that of glass, some force was
tom; asimilar block floats needed to immerse the block of
at the surface.
glass, but as soon as contact had
been secured with the slab below, the block remained at
the bottom. Not only did it show no tendency to rise,
but force was necessary to detach it. As both glass sur-
faces had been carefully cleaned, there could be no cemen-
tation; the phenomenon was one of hydrostatic pressure,
conditioned by the contact relations of glass with mer-:
cury.
In the second experiment water was substituted for
PRESSURE OF TIDAL GLACIERS 213
mercury; and, as glass is heavier than water, the glass
block was replaced by a block of cork, to the bottom of
which a thin plate of glass was cemented. When the
cork was pushed down through the water and its glass
face squeezed against the slab of glass at the bottom, it was
found to adhere, but not permanently. The pressure ap-
plied did not force all the water from between the glass
faces, and the remaining water film gradually thickened,
until, in a few seconds or a few minutes, the cork was
freed and rose to the surface.
As regards conditions, the only essential difference be-
tween the two experiments was in the liquids employed,
and the properties of the liquids which determined the
diverse results were the relations of internal to external
molecular forces. Because the cohesive force of water is
less strong than its force of adhesion to glass, water ‘ wets’
a glass surface; it is able to spread and interpose itself
as a film between two glass surfaces pressed tightly to-
gether; and when thus interposed it can not be forced
out by pressure (at least, by such pressure as is involved
in the problem of the tidal glacier). Because the cohe-
sion of mercury is stronger than its adhesion to glass, it
does not wet glass; and it does not tend to insinuate itself
between closely approximated glass plates, but tends rather
to withdraw from the interspace.
These experiments indicate that the ability of the sea
to penetrate, and communicate its pressure, along the
contact surfaces of a tidal glacier and its bed, may depend
on the cohesive force of water, as compared with its ad-
hesive force in relation to ice and rock. It is a familiar
fact that water wets both ice and rock; and the problem
of the glacier is therefore better represented by the second
of Day’s experiments than by the first.
Another factor of the problem should now be consid-
ered, the temperature of the bottom ice and adjacent rock;
214 ALASKA GLACIERS
for if these fall below the freezing temperature, a film of
water can not exist between them. This is a subject
which has received considerable attention, and although
direct observation is impossible, there seems a good
foundation for inference. By the aid of crevasses and
borings it has been found that the upper ice (outside the
névé region) has at all times a temperature of almost ex-
actly 32°, seasonal and diurnal variation being confined
to a very thin surface layer. The upper ice therefore has
no cooling effect on the bottom ice. On the other hand,
the bottom ice receives heat in three ways: Heat comes to
it by conduction from the interior of the earth; heat is
developed by the friction of ice and waste on the bed-
rock; and the internal work of the flow of the ice devel-
ops heat, of which a part is conducted downward. The
bottom ice therefore maintains a temperature of 32°
(more precisely, the freezing temperature corresponding
to the pressure), and the adjacent rock is slightly warmer.
There is a continual, though very slow, melting of the
basal ice, and a film of water is maintained between it
and the rock. It is probable that the streams of water
which flow from glaciers all through the winter are sup-
plied chiefly by basal melting; and we may further sup-
pose that the tunnels through which those streams flow
are connected with the thin water film by a graduated
and ramifying system of minor passages. The ways
which serve for the escape of the product of basal melting
serve also, in the case of tidal glaciers, for the communi-
cation of the hydrostatic pressure of the sea water.
Statically considered, the film of water under the gla-
cier is subject to a group of forces in equilibrium. The
weight of the glacier presses on it and tends to expel it.
This is resisted by the molecular forces associated with
the contact faces of the film, and by the hydrostatic pres-
sure of the sea water outside. As the film is added to by
PRESSURE OF TIDAL GLACIERS 215
melting, and as the added water must escape by flow,
there is also a dynamic factor, the viscous resistance to
flow. These forces conjointly determine the thickness
of the film. The film is thicker as the ice column is less,
as the sea-water column is greater, and as the melting is
more rapid. It is always very thin.
We may now advantageously return to the question of
the mode of support of the tidal glacier. Referring to the
diagram (fig. 106), it is evident that the ice receives no
support from the pressure of the sea
water against its frontal cliff. It rests
wholly on the film of water beneath
it, and its pressure is communicated
by the film, without loss, to the rock QZ
beneath. The film is not a mere con-_ ric. 106. eat sxc-
duit, communicating the static pres- 710N OF TIDAD GhACIES:
° Showing relation of the
sure of the sea water. If it were, the sea to the subglacial water-
ice would not be supported, because fiw is cuormucly exaggen
that pressure is less than the down- *¢
ward pressure of the ice. In virtue of the molecular forces
brought into play along the contact planes, the film has
some of the properties of a solid. It is, in some sense, an
elastic spring or cushion interposed between the ice and
the rock. It performs its function of transmitting the
pressure of the glacier to the rock bed quite indepen-
dently of the presence of the sea. The pressure of the
sea water modifies the infinitesimal thickness of the film,
but does not prevent the rock bed from supporting (through
the mediation of the film) the whole weight of the glacier.
The last statement is subject to a single qualification.
Wherever the feeble flow of water from basal melting
maintains passages of more than capillary size, the molec-
ular forces locally cease to dominate, and the hydrostatic
pressure of the sea water contributes support to the
glacier. To this extent, which must always be relatively
216 ALASKA GLACIERS
very small, the pressure of a tidal glacier on its bed is
diminished by the sea.
It thus appears that there is no important difference, as
respects pressure on the rock bed, between a glacier rest-
ing on the land and one which is partly bathed by the
water of a fiord; and, so far as glacial erosion is con-
ditioned by pressure, the presence of the sea does not
diminish the efficiency of the glacier. It is possible, how-
ever, that the rate of erosion is affected by changes in the
thickness of the capillary film of water. In the familiar
case of the grindstone, the application of water modifies
abrasion in two ways: It acts as a lubricant to diminish
friction and reduce the efficiency of the stone; and it acts
as a carrier to remove the product of abrasion, prevent
clogging, and thus enhance the efficiency. The sub-
glacial film doubtless has both these functions, and both
should be affected by its thickness; but as the two are
antagonistic in relation to abrasion, it is not at once
evident whether a thickening of the film should increase
or diminish the erosive work of the glacier.
It seems furthermore possible that the influence of film
thickness on abrasion may not be the same for waste par-
ticles of all sizes. It may be important with reference to
the finest rock flour, where the diameters are of the same
order of magnitude as the depth of the film, and quite un-
important with reference to the work of sand and still
coarser waste. And if we turn from abrasion to plucking,
we seem to pass altogether out of the field of influence of
the subglacial film.
While it is not altogether easy to picture the combina-
tion of molar and molecular forces associated with the sub-
glacial film, and while it is still more difficult to analyze
the eftect of variation in that film on so complicated a proc-
ess as glacial erosion, I am nevertheless confident that
the influence of the sea in diminishing the pressure of a
PRESSURE OF TIDAL GLACIERS 217
tidal glacier has been greatly overrated, and I discredit
the supposed power of sea pressure to make important
reduction of a glacier’s efficiency for erosion.
The preceding pages were submitted in manuscript to
several friends competent to consider questions in molec-
ular physics. Some of them think the ability of the sub-
glacial film to resist expulsion has been overestimated, and
especially that the film should not be assumed to exist
between the bed-rock and the abrading angles of rock
particles held in the ice. If it be true that abrading par-
ticles are in absolute contact with the bed, and if it
be further true that there is no film between the same
particles and the partly enveloping ice, then parts of the
glacier (regarded as a body of ice and fragmental rock)
are directly supported by the bed. However important
the distinction may be with reference to a complete
theory of glacial abrasion, it seems to have little bearing
on the question of pressure as here considered. We
may conceive the whole glacier to consist of infinitesimal
vertical columns, some terminating on the bed and sup-
ported by it, others resting directly on a capillary film of
water and thus indirectly supported by the bed, and yet
others terminating on a water stratum of supercapillary
depth. The last are sustained in part only by the hydro-
static pressure communicated by the water stratum, and
are otherwise upheld directly by their coherent neighbors
of the first and second groups, and through then, indi-
rectly, by the bed.
It is a corollary to the general conclusion of this section
that the existence of a fiord — that is, of a glacial trough
partly occupied by an arm of the sea— is not demonstra-
tive of a relatively low base-level at the time of its excava-
tion. In the regions of the Alexander Archipelago and
Prince William Sound there is independent reason to
think the base-level was relatively low when the glaciers
218 ALASKA GLACIERS
were largest, but the case is not strengthened by the pres-
ence of the sea in the glacier channels.
RIVERS OF ICE AND OF WATER
The resemblance which glaciers of the alpine type bear
to streams of water, has impressed all observers, and it
includes so many details of form and work that the phrase
‘river of ice’ seems more than a mere figure of speech.
The fact that resemblances arrest attention, of course im-
plies that there are also differences; the contrast between
the two materials, ice and water, is so extreme that cor-
respondences in their behavior are unexpected and there-
fore striking. If we disregard this fundamental difference
in material and restrict attention to other causes controlling
the phenomena, then we may say that some of the re-
semblances between glaciers and rivers are of the nature
of homologies, in that the causes of the corresponding
features are like, and other resemblances are of the nature
of analogies, in that the causes are unlike. Before attempt-
ing a classification of resemblances on these lines, I shall
enumerate the features of alpine glaciers which have been
regarded, or which seem worthy of regard, as correspond-
ing to similar features of rivers.
Resemblances.—(1) Upland precipitation is gathered
into streams which flow down the slopes. (2) As they
flow they meet and join together, forming greater streams,
which follow the main valleys or gorges. (3) Sometimes
a stream parts against a prominence and reunites beyond
it, thus surrounding an island (nunatak); (4) sometimes
the parted members proceed independently, as distribu-
taries. (5) All parts of the stream are subject to gain
and loss of material. In an upper division gain is in
excess; in a lower division, loss. In complete examples
the maximum volume is in mid-course, and the stream
ends distally by complete dissipation. (6) If the stream
a ——<—_ L e
GLACIERS AND RIVERS COMPARED 219
reaches the sea it is cut off, and its history of volume-
change ends abruptly.
The velocity of flow is greater (7) in the middle of the
stream than at the sides, (8) at the top than at the bottom,
(9) on the outer side of a bend than on the inner, (10)
where the channel is narrow than where it is broad, (11)
where the grade is high than where it is low, (12) ina
large stream than in a small.
(13) The surface of the stream, considered as to its
major features, is smoother than the channel bed. (14)
It is exceptionally high on the upstream side of an island,
and exceptionally low on the downstream side. (15) It
is roughened in detail by concealed prominences of the bot-
tom, especially where the stream is shallow. (16) The
surface descends normally in the direction of flow, but
exceptionally, and for short distances, ascends.
(17) The stream erodes its bed and the walls of its
channel. (18) The chief tools of erosion are rock frag-
ments carried by the stream. (19) The greater the
velocity of the stream the more rapid the erosion (except,
perhaps, in cirques). (20) The stream shapes its chan-
nel, making the width several times greater than the
depth. (21) The fully adjusted channel is broader in
yielding material than in obdurate; but has uniform width
in uniform material. (22) The contours of the adjusted
channel are smooth curves of large radius. (23) The
adjusted channels of large streams are broader and deeper
than those of small streams. Where a large stream is
joined by a small tributary and the surfaces of the two
have the same level, the bed of the large stream lies lower
than that of the small. (24) The erosion of the channel in
gorges saps the cliff walls, causing coarse waste to fall to
the stream. (25) The waste from erosion and sapping is
carried forward by the stream and eventually deposited.
(26) Where a heavily loaded stream issues from a moun-
220 ALASKA GLACIERS
tain gorge to an open valley, it sometimes deposits waste
at the sides and beneath until it comes to flow in a walled
causeway, or raised trough, of its own construction. It
may then overflow a wall of the trough and assume a new
course." :
Differences.— The features of difference are equally
noteworthy. The speed of the glacier is very much
slower than that of the river, being better expressed in
feet per year than in feet per second. The rates of wax-
ing and waning are correspondingly slow. A river flood
is propagated downstream by the actual transfer of the
water added about the upper course; a glacier flood is
believed to be propagated downstream as a wave travel-
ing more rapidly than the ice. The depth and width of a
glacier are much larger, in relation to length, than those
of a river. The threads of flow in a glacier run nearly
parallel; in a river they weave freely in and out. That
which falls to the back of a glacier, though much denser
than the ice, does not sink to the bottom, but is carried for-
ward as a back-load; only light materials float on a river.
Most of the waste embedded in a glacier is moved along
continuously; most of the waste constituting the load of
a river is transported intermittently, being repeatedly
picked up and laid down.
Homologies and Analogies.—The gathering of ice into
streams and its downward flow are caused by gravity, just
as inthe case of water. Most of the inequalities of veloc-
ity are determined by gravity in conjunction with the fric-
tion of the ice on the channel and the resistance of ice to
internal shear; and the processes are essentially the same
as with water. But the greater velocity on the outside
of a bend involves an analogy only. The bending stream
of ice distributes the velocities of its elements in such
1]. C. Russell. Eighth Ann. Rept. U.S. Geol. Survey, part 1, pp. 337-342,
360-366, 1889.
GLACIERS AND RIVERS COMPARED 221
way that the total work of channel friction and internal
shear is a minimum, and that distribution throws the locus
of maximum velocity to the outer side of the middle of the
stream, but the general relations of the parts of the stream
are not changed. The preservation of the general rela-
tions is clearly shown by medial moraines, which map out
surficial lines of flow. Inthe bending river, momentum
is the controlling factor. Those fillets of the stream which
above the bend moved fastest are thrown to the outer side
of the curve, and the slower-moving fillets are crowded to
the inner side. Usually the upper water moves to the
outside of the bend and the lower water to the inside, so
that there is a torsion of the body of water as a whole.
The correspondences connected with gain and loss of
material are close, and the parallelism can be traced
through many details, but the processes are so different
that the similarities of result can not be classed as homol-
ogies. Alimentation of the glacier is primarily through
snowfall, secondarily through rainfall, and there is storage
in snow banks that subsequently descend as avalanches.
Alimentation of the river is primarily through rainfall,
secondarily through the melting of snow and ice, and
there is storage in ground water that slowly issues in
springs. Dissipation of the glacier is chiefly by melting
and secondarily by evaporation. Dissipation of the river
is wholly by evaporation, but part of its evaporation is
preceded by absorption by the ground.
The general evenness of the stream surface is deter-
mined in each case by gravity, and so is its descent in the
direction of flow; but the exceptional ascent in the direc-
tion of flow has diverse causes. Where the passage of
an ice stream over an embossment of its bed is expressed
by a local rising of its surface, the imperfect adjustment
of the surface is a result of viscosity; the upward slope of
water under similar circumstances is a result of impetus
222 ALASKA GLACIERS
or momentum. So, too, the roughening of the glacier
surface where the flow is disturbed, by breaking into
seracs and pinnacles, is analogous to, rather than homol-
ogous with, the breaking of a river surface into waves.
Viscosity causes the rupture of the ice, momentum the
undulation of the water. The deflection of the viscous
ice produces stresses and strains, some of which are ten-
sile; in the depths of the stream the tensile stresses are
balanced by compressive stresses due to the weight of
overlying ice, but higher up the ice is overstrained and
ruptured. When the swift-flowing water rises over an
obstruction its momentum causes a portion to shoot above
the normal level, and thus starts an undulation.
The causes of the relation of channel depth to channel
width are not sufficiently understood in the case of glaciers
to warrant a comparison with rivers. The disparity of
channel depth at the mouth of a small, fully-adjusted trib-
utary is in each case a phenomenon of base-level con-
trol. The surface level of the tributary is determined by
the main stream, and if the tributary at any time erodes
its channel rapidly, its stream becomes deeper, its velocity
less, its power to erode less, and thus the tendency to
deepen is limited. The resemblance of glaciers to rivers
in this respect is a homology.
The adjustment of channel contours to simple curves is
brought about, in both classes of streams, by the more
rapid erosion of projecting angles, but the work of the
water is concentrated on these through the property of
momentum, and the work of the ice through viscosity.
The walled causeways sometimes built by streams of
ice debouching onto a plain have a different process of
construction from the similar causeways occasionally built
by streams of water. The walls of the glacial causeway
are made by the deposition of lateral moraines that had
been carried chiefly as back-load. The walls of the fluvial
VISCOSITY AND MOMENTUM 223
causeway are made by the deposition of suspended waste
through the slackening of spreading side currents.
The salient fact brought out by these comparisons is
that many features of rivers and river work which arise
from inertia in association with swift motion are paralleled
by features of glaciers and glacier work which arise from
high viscosity in association with slow motion. In each
kind of stream, changes in the direction of flow are caused
by irregularities of the channel, and complex series of
phenomena arise from the resistance of the current to
deflection. These series are strikingly parallel, but the
resistance to deflection is occasioned in one case by
momentum and in the other by viscosity.
INDEX
Abercrombie, Captain W. R., map 72
Acknowledgments, assistance by col-
leagues 10
photographic material 5
Alexander Archipelago, depth of fiords
134
fiords 150-159
pre-glacial topography 130
Amherst Glacier 82, 82 (pl.)
Annette Island 130
Baranof Cape 132, 132 (pl.)
Barry Glacier 90-93
Base-level, pre-glacial 134
Base-level plains. See Peneplains.
Base-levels, Pleistocene 162-166, 172,
184
Becker, G. F., cited on glacial erosion
204
cited on statics of tidal glacier 212
Behm Canal 128, 134, 140, 159
Bendeleben Mountains 193
Bering Sea 186-194
Berner Bay 127, 140
Biological Survey, U. S., acknowledg-
ments v
Alaska photographs 5, 6
photograph of Wellesley Glacier
88
photograph of Yale Glacier 83
Bonney, T. G., cited on hanging val-
leys 114
Boundary Commission. See Canadian
International Boundary Commission.
Brabazon, A. J., photographs 27, 28, 29,
38
Brady Glacier 45, 106, 123
British Columbia, glaciation of coastal
region 141-150
Brooks, A. H., geology of Seward
Peninsula 192
Bryn Mawr Glacier, frontispiece, 87,
88, 175
Canadian International Boundary
Commission, acknowledgments v
maps and photographs about Gla-
cier Bay 16, 25, 26, 28, 29, 38
maps and photographs about Lynn
Canal 12, 13, 15
maps and photographs about Ya-
kutat Bay 46, 62, 65, 67, 209
photograph series 6, 122
photographs of fiords 158
photographs of upland topography
123, 125, 127, 128, 140
Cape Baranof 132, 132 (pl.)
Cape Spencer peneplain 123-126, 141
Cataract Glacier 94
Cascading glacier, Nunatak Fiord 61
glaciers, College Fiord 89, 175
Caves in Barry Glacier 91
Chamberlin, T. C., cited on hanging
valleys 114
Charpentier Glacier 34-37
Chatham Strait 134, 151-155
Chatham Strait Glacier 162
Chilkat Inlet 13, 15
Chilkoot Lake 141, 154
Chiniak Bay 179
Cirques 141
Clarence Strait 134
( 225 )
226 INDEX
Coast Survey, U. S., maps 12, 15, 26,
49; 50, I19
photographs 122, 187
soundings 158
College Fiord, existing glaciers 81-89
map 8o (pl.)
Pleistocene glaciation 175-176
Collier, A. J., cited on geology of
Seward Peninsula 192
Columbia Bay 73, 81, 174
Columbia Glacier 70 (pl.), 71-81, 104
surface features 200
Columbia River 137
Coville, F. V., acknowledgments 10
observation of young spruces 78
visit to Columbia Glacier 71
Crescent Glacier 82, 82 (pl.)
Crevasse cycle 198-203
Curtis, E. S., official series of views 5
photographs of glaciers 6, 74 (pl.),
86, 88, 94, 94 (pl), 95
photographs of Wrangell and Sitka
132 (pl.)
Cushing, H. P., geologic studies in
Glacier Bay 16, 17
Dall, W. H., acknowledgments 10
cited on Kadiak terraces 179
cited on Pleistocene glaciation 187
observations of Grewingk Glacier
98, 100
Pleistocene shells 165
Dana, J. D., cited on glacial erosion by
plucking 207
Davidson Glacier 12-16, 105, 157
compared with glacier of Russell
Fiord 51
compared with Pleistocene glaciers
of Fairweather Range 169
Davis, W. M., cited on hanging val-
leys 114
Dawson, G. M., Alexander Archipelago
141
cited on ancient glaciers of Van-
couver Island region 145
cited on geology of coast ranges
129
Day, A. L., experiments 212
Denudation. See Erosion.
Discovery Passage 143
Disenchantment Bay 46-49, 62 (pl.),
63-70, 104
Doran Strait 90
Disenchantment Bay Glacier 49
Douglas Island 132, 165
Drift 35, 161 ,
influence on topography of glaciers
202
Dutch Harbor 185, 210
Earthquake 23
Emerson, B. K., acknowledgments 10
Erosion, by glaciers and rivers com-
pared 218-223
by Pleistocene glaciers 139-163
by tidal glaciers 210-217
fiord 162
principles of glacial 203-210
Estuaries, coast of Washington 137
Fairweather Range 39, 123, 125, 126
existing glaciers 148-150
La Perouse Glacier 39-45
Pleistocene glaciation 166-170
variations of glaciers 105, 107
Fiord erosion 162
Fiords, Inside Passage 141-150
strike 125, 142-157
transverse 142, 157-159
Fiords and islands 119-122
Fish Commission, U. S., photographs
44, 65, 67
Fort Wrangell 132 (pl.)
Fraser Reach, hanging valleys 145-147.
Gannett, Henry, acknowledgments 10
cited on cascading glaciers 175
cited on hanging valleys 114
map of Alaska 1 (pl.)
map of Disenchantment Bay
62 (pl.), 65
map of Hidden Glacier 52 (pl.)
map of Muir Inlet 21
map of Nunatak Glacier 58 (pl.),
62
map of Port Wells 80 (pl. ), 81
route 4
Garwood, E. J., cited on hanging val-
leys 114
INDEX
Gastineau Channel 132, 165
Geikie Glacier 38
Geikie Inlet 38
Geological Survey, U. S., acknowledg-
ments v
photographs by 5, 6
Georgia, Gulf of 134
Glacial deposits 161
Glaciated rocks 206 (pl.)
Glaciation, Pleistocene 113-194
Glacier, Amherst 82, 82 (pl.)
Barry 90-93
Brady 45, 106, 123
Bryn Mawr frontispiece, 87, 88,
175
Cataract 94
Charpentier 34-37
Chatham Strait 162
Columbia 70 (pl.), 71-81, 104, 200
Crescent 82, 82 (pl.)
Davidson 12-16, 51, 105, 157, 169
Disenchantment Bay 49
Geikie 38
Grand Pacific 26-33
Grewingk 97-102, 104
Harriman 94, 94 (pl.)
Harvard 82, 84
Hidden 47, 52 (pl.), 52-58, 202
Hubbard 47-49, 62 (pl.), 63-70,
196
Hugh Miller 34, 35-38
Johns Hopkins 27, 28, 32, 106
La Perouse 39-45, 104, 167
Malaspina 46, 49, 106
Muir 20-25, 198, 199
Nunatak 47, 58 (pl.), 58-63
Puget Sound 135, 139
Queen Charlotte Sound 145
Radcliffe, 84-87, 175
Reid 27, 28-32
Roaring 96
Serpentine 93
Smith 86, 87, 175
Strait of Georgia 145
Surprise 94
Turner 47, 62 (pl.), 64, 66 (pl.),
66-69
Vassar 88, 175
Wellesley 175
2247
Glacier, Wood 38
Yale 82, 83
Glacier Bay 16-39
variations of glaciers 103
Glaciers, annual cycle 22
basal melting 214
cascading 61, 89, 175
causes of variations 102-112
classification 10
College Fiord 81-89, 175-176
comparison with rivers 218-223
dates of photographs 5
existing 7-112
general distribution 7-9
Glacier Bay 20-39
hanging I1, 114-119
Lynn Canal 11-16, 126, 134, 150-
157
piedmont 10
Pleistocene 113-194
Port Wells 81
pressure and erosive power in
fiords 210-217
principles of erosion and sculpture
203-210
relation to forests 41-44, 45, 49, 51,
52, 76, 78-80, 88, 92, 95, 96, 98,
IOI, 106
sculpture by Pleistocene 139-163
summary of modern changes 102-
106
surface characters 196-203
tidal 11, 210-218
Glenn and Abercrombie, map 72
Graham Island 165
Grand Pacific Glacier 26-33
Gray Harbor 137
Grenville Channel 146
Grewingk Glacier 97-102, 104
Gulf coast, summary of Pleistocene
geology 182-185
Gulf of Georgia 134
Haenke Island, contact with Hubbard
Glacier 48, 70
photographs 65, 67
position 47, 50
Hall Island 188
Hanging glaciers 11, 114-119
228 INDEX
Hanging glaciers, in Harriman Fiord
93, 94, 95, 176.
See also Hanging Valleys.
Hanging valley, Kadiak Island 181
Plover Bay 191
Princess Royal Island 116 (pl.)
Hanging valleys 114-119
Inside Passage 142-150
Lynn Canal 153, 154
Nunatak Fiord 60, 61
Yakutat Bay 170
Harriman, E. H., photograph by 95
Harriman Fiord 80 (pl.), 89-97
Pleistocene glaciation 176
Harriman Glacier 94, 94 (pl.)
Harvard Glacier 82, 84
Hayes, C. W., cited on height of névé
line 8
Hecate Strait 134
Hidden Glacier 47, 52-58, 52 (pl.), 202
High mountain district 166-173
Hinchinbrook Island 174
Hubbard, Gardiner G. 63
Hubbard Glacier 47-49, 62 (pl.), 63-
70, 106
Hugh Miller Glacier 34, 35-38
Hugh Miller Inlet 34-38
Ice. See Glacter and Viscosity.
Iceberg waves 31, 69
Icebergs, Muir Inlet 24
Reid Inlet 33
Iliuliuk 186, 210
Inertia of rivers compared with vis-
cosity of glaciers 223
Inland Passage district 119-166
Inside Passage 121, 142-150
Inverarity, D. G., photographs by 62,
92, 94 (pl.)
Island, Annette 130
Douglas 132, 165
Graham 165
Haenke 47, 48, 50, 65, 67, 70
Hall 188
Hinchinbrook 174
Kadiak 177-182, 189
Montague 176
Osier 47, 65, 69
Pitt 146
Island, Princess Royal 116 (pl.), 145,
146
St. Matthew 188, 193
St. Paul 187
Unalaska 185
Vancouver 143-146, 165
Islands, Queen Charlotte 165
Islands and fiords 119-122
Itinerary 3
Johns Hopkins Glacier 27, 28, 32, 106
Johnstone Strait 143
Kadiak Island 177-182, 189
Kenai Peninsula 97, 177
Kerr, M. B. 1
Kettle-holes, near Grewingk Glacier
100
near Hidden Glacier 54 (pl.), 54-
56
Kigluaik Mountains 192
Klotz, Otto J., cited on variations of
glaciers 45, 103
La Perouse, J. F. de G., exploration of
Lituya Bay 45
observations of Disenchantment
Bay Glacier 51
La Perouse Glacier 39-45, 104, 167
La Perouse Peak 123
Lituya Bay 149, 150, 167
Lowe Inlet 148
Lynn Canal, configuration of bottom
134
glaciers 11-16
origin of 150-157
upland topography near 126
McArthur, J. J., photograph by 13
Malaspina, A., visit to Disenchant-
ment Bay 48
Malaspina Glacier 46, 49, 106
Map of Alaska, showing route 1 (pl.)
Mendenhall, W. C., cited on glaciation
of Alaska Peninsula 192
Merriam, C. Hart, photographs by 5, 6
photograph of Amherst Glacier
82, 82 (pl.)
preface v
Montague Island 176
Moraine, section 56 (pl.)
ae
ee. ee ee
INDEX
Moraine-building at sea front 163-165,
168-170
Moraine delta, Davidson Glacier 13-16
Grewingk Glacier 97
Hidden Glacier 52-57
Muir Glacier 19
Moraines, base of Fairweather Range
166-170
near Yakutat Bay 171
overridden by Columbia Glacier
77
under Yakutat Bay 49-51
Moraines, push-, Columbia Glacier
76-80
Grewingk Glacier 100
La Perouse Glacier 42
Muir, John, acknowledgments 10
cited on Hugh Miller Glacier 35
cited on Pleistocene glaciation of
Bering Sea region 186
exploration of Glacier Bay 16, 17
route in 1899 3, 4
studies of Brady Glacier 45
studies of Geikie Inlet 38
studies of Grand. Pacific Glacier
26, 29, 32
studies of Muir Glacier 21
visit to Harriman Fiord 81
Muir Glacier 20-25
limit of crevasses 198
seracs 199
Muir Inlet, glacial erosion 207
ice pack 24
map 21
Nanaimo 165
Nordenskiold, A. E., cited on glacia-
tion of Siberia and Alaska 187, 192
Nunatak Fiord 46, 58, 61, 62
Nunatak Glacier 47, 58 (pl.), 58-63
Ocean Cape 170
Ogilvie W., photograph of Davidson
Glacier 12
Orca 174
Osier Island 47
ice-fall waves 69
photographs 65
Palache, Charles, acknowledgments 10
229
Palache, at Columbia Glacier 71
route 3, 4
Penck, A., cited on hanging valleys
114
Peneplains, high, Kadiak Island 177,
183
Kenai Peninsula 177, 183
Prince William Sound 172, 183
southeastern Alaska 123-130, 183
Peneplains, low, Alexander Archi-
pelago 130-134, 159, 183
glaciation of 209
Kadiak Island 179, 180, 182, 183
Photographs of glaciers 4
Pitt Island 146
Pleistocene glaciation 113-194
Plover Bay 190
Plucking 203, 205, 207-209
Port Clarence 188
Portland Canal 134, 159
Port Wells 80 (pl.)
existing glaciers 81-97, 104
Pleistocene glaciation 175
Pre-Pleistocene topography 122-139
Pressure of tidal glaciers 210-217
Prince William Sound, ancient base-
levels 172
existing glaciers 71-97
map 80 (pl.)
Pleistocene glaciation 173-176
Princess Royal Island, hanging valleys
116 (pl.), 145, 146
Puget Sound 135
Puget Sound Glacier 135, 139
Push-moraines, Columbia Glacier 76-
80
Grewingk Glacier 100
La Perouse Glacier 42
Queen Charlotte Islands 165
Queen Charlotte Sound 134
Queen Charlotte Sound Glacier 145
Rabot, Charles, cited on cause of gla-
cial variation 106
Radcliffe Glacier 84-87, 175
Reid, H. F., cited on cause of glacial
variation 109
cited on variations of glaciers 103
nomenclature of glaciers 11
230 INDEX
Reid, H. F., studies of Muir Glacier
at, 23
survey of Glacier Bay 1, 16, 17,
25, 26, 28, 29, 38
Reid Glacier 27, 28-32
Reid Inlet 25-34
Rivers of ice and water compared 218-
223
Roaring Glacier 96
Rock table 201
Route, map of 1 (pl.)
of author 3
of Expedition 1, 2,3
Russell, I. C., cited on buried forest 52
cited on Disenchantment Bay and
Russell Fiord 48
cited on glaciation of Unalaska
Island 185
cited on Hidden Glacier 56
cited on marine shells 173
cited on nomenclature 11
cited on Nunatak Glacier 62
cited on variations of glaciers 103
classification of glaciers 10
Davidson Glacier 13
photograph of Hubbard Glacier 65
photograph of Turner Glacier 66,
66 (pl.)
studies in Glacier Bay 16, 17
survey of Malaspina Glacier 1, 46
Russell Fiord 46, 47, 51-63, 69
types of glacial erosion 208
St. Elias Alps 166
height of névé line 8
recent uplift 173
St. Matthew Island 188, 193
St. Paul Island 187
Sea-levels, Pleistocene 162-166, 172
Seracs 198
Serpentine Glacier 93
Seward Peninsula 192
Shaler, N. S., cited on pressure melt-
ing 204
Shells, Pleistocene 165
Siberia 190, 193
Sitka 131, 132 (pl.)
Smith Glacier 86, 87, 175
Speel River 158
Spencer Cape, peneplain 123-126, t41
Spurr, J. E., cited on terraces of Un-
alaska Island 186
Stevens Passage 134
Strait of Georgia 134
Strait of Georgia Glacier 145
Streams of ice and water compared
218-223
Surprise Glacier 94
Terrace, Annette Island 130
near La Perouse Glacier 167
Seward Peninsula 193
Spruce Island 179
Terraces, Prince William Sound 176
Unalaska Bay 186
Yakutat Bay 170
Tidal glaciers 11
Tidal glaciers competent to erode 210-
217
Tittmann, O. H., ice pack in Muir In-
let 24
Tracy Arm 159
Turner Glacier 47, 62 (pl.), 64, 66
(pl.), 66-69
Unalaska Bay, glaciation of 209
Unalaska Island 185
U. S. Biological Survey, acknowledg-
ments iii
Alaska photographs 5, 6
photograph of Wellesley Glacier 88
photograph of Yale Glacier 83
U.S. Coast Survey, maps 12, 15, 26,
49, 50, 119
photographs 122, 187
soundings 158
U.S. Fish Commission, photographs
44, 65, 67
U.S. Geological Survey, acknowledg-
ments v
photographs by 5, 6
Uyak Bay 178
Vancouver, George, cited on Columbia
Glacier 71
map of Columbia Bay 71, 80
observations in Disenchantment
Bay 48
observations in Glacier Bay 17
—
-
INDEX
Vancouver, George, observation of
Brady Glacier 45
Vancouver Island, hanging valleys
143-146
marine clays 165
Variations of glaciers 102-112
Vassar Glacier 88, 175
Viscosity of ice, compared with inertia
of rivers 223
in relation to glacial erosion 204
Walker Bay 128
Waste plain, Davidson Glacier, 13-
16
Grewingk Glacier 97
Hidden Glacier 52-57
Wellesley Glacier 175
231
Whidby, Joseph, cited on Columbia
Glacier 71
Willapa Bay 137
Willis, Bailey, cited on Puget Sound
Glacier 135
Wood Glacier 38
Wrangell 132 (pl.)
Wright, G. F., studies in Glacier Bay
16, 17, 21
Yakutat Bay, submerged moraines 49-
51
terraces 170
Yukutat Bay region 45-70
Yakutat village 170
Yale Glacier 82, 83
York Mountains 193
; eakatiiecee rote! <
:. 7% S
sath be * a he
: . « ¢ -
se u
< x i
: «
“ =
- We tae) wae a —* puis
— nee i N ete
— ach
=
Sy =e AE . ‘
ee
—
. 3 ~
~> ” =
- ee ue :
¢
=
-
i =
Q Harriman Alaska E
115 Harriman Alaska
H37
ve3
PRA Sci,
PLEASE DO NOT REM
CARDS OR SLIPS FROM THI
UNIVERSITY OF TORONTO
aoe Z : eae a 2 ae Scweaeee rer 2 =
4 - _ : io, x8 reer 3 wees ate x : pen sm eae ee ee n se parshy
" KA =) cs g
Sere
CS Sere =
SS Spa ereynamataaleehiet 8/te imap tke
e
totem
ee TT
“anya, ByS Gh Fatah 2 :
Setqe ae na TEetasen aa Rahoalgna aah beng ty
Fg ng Rage dys tohpeph Achim int
; ona 2
reeeS SS ACW S PLN SCARE WE ME PCTS OS ST . < ee eae pereetinee ; % eaten aes re :
Le babatte kedk aS EL TDR ey ha = 7 Hane Hoe ns vet 5 * + . yeqeyee > - —— : — ~ — ae reverie : Aeieto® tad re s acest S
ao — = Te lokctekald eeahe hae Sat i sewrevietet oe 7 5. 5 . " one —_ . r en —r- ames : acetate r LSE SENT TW a WPS 9 RE TE See ATEN ee PY NT
- ee = wore * ee wh BRIBED tee mel he Sib haderqwenwse ne tnt; Pr tt ~
strovedenan sake Renpeetetcieietey atta et
aan eo =
reer B
tetcietete. mectatahat ta tal 68s Spas bod
Soave e sicee Bein heiaehenck fitch gh Ais sRgty Oy Wi, OrbaP rts 2sOeGyE
ee,
win jt penne ay Ost PE Res) WE
: peseptrsd ies
5
r
i
ce not Pcanetotrsenntat jayytsdyayt)tresey@eteselet
eer hele Sates
pateica® yest yt) pane anenaty Sey gy 8-426;
Sgiapighy teh
tote tak esy yt, 8, Poly!
CICSen er errors pysans 38 tats
21, Wy) peewee wR opt emai Seb®
Howe ee
zy
ah
SSUES SION eee eee
eee newest
“ oes i 2 7 : c Es R : " he Mnegter are. S
atghasatered ; ot ™ : ms ~ Se a ~s o irc 2 wsoce sinter.
Eceeatacopaes vs > ~ fe 2 oot ; . ne pan) ay ol oe
* : —— . nena pa ~ ~ ew — = i 6 3 ~ “ soe : . = ? ? Se w
eee ERIC
Rawk ona tee
iedplnioneinentyesyy cre sitet
Live Music Archive
Librivox Free Audio
Metropolitan Museum
Cleveland Museum of Art
Internet Arcade
Console Living Room
Books to Borrow
Open Library
TV News
Understanding 9/11