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Glaciers of North America,

Plate l.

Sketcli map showing the distribution of goino of the better-known sUiciors of North America
Southern limit of Pleistocene ice sheet intlicateil by a heavy broken line.

o • I

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• « • • •
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• • • • •

• • I • ■

GLACIERS

]^OETH AMEEICA

A READING LESSON FOR STUDENTS OF
GEOGRAPHY AND GEOLOGY

ISRAEL C. RUSSELL

PROFESSOR OF GEOLOGY, rNIVKRSITY OF MirHIOAK. AUTHOR OW
"LAKES OF NORTH AMERICA," ETC.

GiNN & 'Compact''/' '

« I' #

■> t .

3 » » I

IS J » ••

» • . ^ I

• Re

ALL AIOHTS RESERVED
30.8

• «

« • «

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, ^ GINN' ,V COMfANY . PRO.

• ••

• •

»• •

* •
« • ■

TO THE EEADER.

-*oj»-:o<-

Until within the pafit few years, nearly all current knowledge of
glaciei-s was based on the study of those of the Alps. Practically all
theories of the orrgin, growth, motion, etc., of glaciera were inspired from
the same source. An enlargement of the field of study, however, has
shown not only that glaciers of the same type as those of Switzerland exist
in many other lands, but in numerous instances are larger and present
greater divei'sity ; and besides, additional types or " genera " have been
discovered that are not represented in Europe or in fact on any of the
three continents of the Eastern Hemisphere.

As geological and geographical explorations have been extended, it
has been found that North America is not only a favorable field for the
growth of these twin sciences, but in many ways furnishes the best
example of continental development that has as yet been studied. Strange
as it may appear in the face of the overshadowing popular interest that
centers in the glaciers of the Alps, North America offers more favorable
tonditions for the study of existing glaciers and of the records of ancient
ice sheets than any other continent. Of each of the three leading tyj^es
of glaciers thus far reorganized, namely, the alpine, piedmont, and conti-
nental, North America furnishes magnificent examples. In fact there is
no other continent, except the little known region about the South Pole,
in which other than the alpine type of glaciers exist. Of alpine glaciers
representatives occur in North America in abundance and in great variety,
ranging from the " pocket editions " about the summits of the High Sierra,
California, to the magnificent Seward glacier, Alaska, the largest river of
ice flowing from a mountain group that has yet been disco^Aered. Of
piedmont glaciera, the type specimen, so to speak, and the only one of
the class yet explored, is the great ice sheet that intervenes between

TO THE UEAUKU.

Mount St. Elias ami the Pacific, known as tlie Malaspina glacier. The
still larger continental glaciera — of the nature of tlie ice sheet that
formerly covered the northern half of North America, and the smaller
sheet beneath which northwestern Europe was once buried — are repre-
sented in the Northern Hemisphere at the present time by a single
example in Greenland.

The magnificence of the field for glacial study in North America has
only l)e3n appreciated within recent years, and is still unrecognized out-
side of a limited circle of special students. By gathering in the book
before you the information now available concerning North American
glaciera, it has been my aim not only to report the present condition in
this country of an important branch of geological and geographical enquiry,
but to make you familiar with glacial phenomena in general and stimu-
late a (hirst for fresh explorations and renewed study along an almost
untrodden path.

From what I have seen personally of the glaciers of the United States
and Canada, and from glimpses obtained in previous years of thooe of
Switzerland and New Zealand, as well as from all that I have read con-
cerning the ice fields of other lands, I think I can affirm, without fear of
contradiction, that southern Alaska and adjacent portions of Canada offer
one of the most promising fields for glacial study that can be found. I
shall be more than repaid for the labor expended in writing this little
book if it leads even indirectly to a renewal of the explorations now barely
begun in that instructive, highly picturesque, and most attractive region.

Israel C. Russell.

co:n^teis^ts,

CHAI'TEU I.

iNTRODt'CTION

A typical glacier. — Variations from the type. — The term " glacier " indeflnlte.

LkaIMNO ClIAKAtTKlUSTICS OK 'jI-AClERS

Mode of nccuimilation. - Hnu- of flow. - Three types of glaciers ; alpine, piedmont, and
continental.— Divisions of tin- surface of a glacier, n<5ve and glacier i>roper. - Handed
structure.- ({lacier grain. - Moraines : lateral, medial, terminal, and frontal. - Crevasses.
— The starting of ercvussfs. — IJergsclirunds. — Ice falls. — Marginal crevasses. — Surface
features : glaci.-r tables, sand cones, debris pyramids. — .Melting and drainage ; super-
glacial and subglacial streams. — Characteristics of streams Uowing from glaciers.

WiiA IS A Glacier ? . . .

Glacial Ahrasion

Worn and striated rock surfaces.

Smoothed and Striated Siriaces not Produced by Glaciers

Scorings made by river and lake ice and by ice ttoes.
Special Featlres of Glaciated Surfaces

Semilunar cracks, chatter marks, disrupted gouges, etc.

Glacial Deposits , _ .

Lateral moraines. - Perched blocks. - Terminal moraines. - Morainal embankments.
— Frontal moraines. - Interlobate moraines. — Till. — Boulder clay. — Drumlins.

Glacial Sediments

• • • • • • . . ,

Osars. — Kanies. — Sand and gravel plains.
Changes in Topography Produced by Glaciers

CHAPTER II.

General Distribution of the Glaciers of North America

Cordilleran region. — Greenland region.

PAGE
1

16
18

28
30

CHAPTEU III.

Glaciers of the Sierra Nevada ^ 07

The High Sierra „_

Southern limit of glaciers in the United States,

Mount Dana Glacier \ „,.

Mount Lyell Glacier .... .n

... 40

Parker Creek Glacier ... .,,

• • 41

CONTENT8.

ClUHACTEKISTICS OK TIIK GlaCIKHS OF THE IIuJH SlEHHA

Wv.%.-Cr«v««8e«._ Lh, atl.... or rll.lK„.e.l «t,uctur«. -Dirt' b.ui.l..-«iacler 'trfbles'

LntV'^'r:,."""^'".'"'"";"'- ""'""•■""'"' ''"■^""*''' '""' """t"'"-'! .ton... -<Jlacler .uovel
nients. -Glacier im.d.- Ice toi.gueH or devir* slkleH. _ ited »now. -Surface melting.

Pioneer Explorations in the High Sierra

John Mulr -Jo«e,.h Le Conte. - Geological Survey of California. -J. U. Whitney -
Clarence King. - Coniiilions favoring obnervationi.

Ancient Glaciers ....

rAoa

CHAPTER IV.

Glaciehs of Northern California and the Cascade Mountains .

Volcanoeg of the Paclflc coaat.
Mount Shasta

Observations by Clarence King. - Observations by Gilbert Thompson.
MoiNT Rainier (Tacoma)

Glaciers In the Unlte.l States first reported by A. V. Kautz. - Observations by S F
hmmons. — Uecent fwcents. '

Mount Hood

Observations by A. Wootl. - Observations by Arnokl Hague.

Mount Rakek

• . .

Observations by E. T. Colman, J. S. Diller, andJ. S. Newberry.

66
66
62

07
69

CHAPTER V.

Glaciers op Canada

W^'s'lfrTn"' m ^°;'"»«'-'«- -«"*«'«" "' t>»e Sel-irk mountains. - Observations by
W. S Green. - Illecellewaet glacier. - Glacier of the Siiklne Kiver region. - Glaciers of
Northwestern Canada described In connection with those of Alaska.

CHAPTER VI.

Glaciers of Alaska

Topographic an.l climatic conditions favoring glaciation. - Height of Mount Login and
ot Mount St.EIIa8.-Narrative8 of early voyages. - Belcher, Vancouver, and otlfers-

r^rZbTc^VHsr- " "• "*'-^-^' ''■ «• "---«- ---s-

Tide-water Glaciers

Hutu glacier. — Norris glacier.

Taku Glacier . . .

**■•••..
Mum Glacier . .

Indian names. -Muir's exploration. - Observations by Trofessors Wright and Reid 1
Msit by the present writer. - Glacier bay. _ Thickness of the Ice. - IcebergT two
hypotheses concerning. - An ancient forest beneath the ice. - Characteristlcs^f tie
glacier's surface. - Dying glacier. - Recent recession. - Vancouver's observa on on he
former extent of glacial ice in Glacier bay. o"»ervauon on tne

Glaciers on the West Side of Glaciek Bay
Pacific glacier. — Glacier of Dundas bay.

78
80

■i
I

PAGE

66
66

. 67

CONTENTS. VJI

I'.VdK

Glaciers ok Disenciuntment Bat U2

Turiii-r, Hubbard, and Nuiiatak glaciers. — View from Ua^^nke iiland. — View from
Oaier inhind. — Caiio Enciiantiiient.

Icy Cai'k ". . . . . . .96

AlI>INE (il.ACIERA 90

Vaiit ik'vi'i region aUxit Momiti! Fiilrweatlier, Lugaii, aiid Ht. Eliai. — View nortliward
from Mount St. Kliaa. — 8eward glacier. —ice falls and rapids. — Agassi:^ glacier.—
Uuyot glacier.

Olacikrs of Lynn Canal 101

Tnya inlet. — Cl.ilkat Inlet. — Davidson glacier.

Glaciekh of the Interior 104

(llncitTH of Chilkoot and C'hi'.kat passes. — Observations W>' E. T. Olave. —Glaciers be-
tween Yukon luul topper rivers. — Ubservatioi of C. W. lliiyes. — Fredrick Schwntka. —
H. T. Allen.

AbAENCE of (iLACIEKS IN CENTRAL AND NORTHERN AlAHKA .... 107

Gla( ii;iis OK THE Alaskan Peninsula ano the .ileltian I.'iLANiis . . . 10b
Mt. Mukiishin.

Piedmont Glaciers • . 100

Characteristics. — Bering glacier.

Malaspina Glacier 109

Area. — Lobes. — Characteristics of the uon-moralne-covered surface. — Moraines. — Sur-
face of the fringing moraines. — Forests on the moraines. — Character of the outer nuirgin.

— Icy cape. — Sitkagi bluifs. — Marginal lakes. — Crater lake. — Lake 'Jastani. — I.akes
about the Clialx hills. — Drainage. —Fountain stream. — Vahtse. — Osar, Kame.nnd Kiwik
streams. — Sub- and englacial deposits. — (Jsars. — Alluvial cones. — (ilaclal and ocean
records. — Kecent advance of the ice. — Fossil shells of living marine species at high
elevations.

Subsoil Ice . . • 127

Frozen subsoil along the Yukon. — Lieut. CartwcU's explorations on Kowak river. — Ice
cliffs of Kschscholtz bay. — Remains of the mammoth. — Character and origin of the
tundra. — Deptli of frozen subsoil in Siberia. — Explanations of the origin ()f subsoil ice.

— Computations of Prof. K. S. Woodward. — A possible origin of frozen subsoil.

CHAPTER VII.

78
80

Glaciers in the Greenland Region

Grinnell Land

Observations by members of the Lady Franklin Hay expedition. — Report by Gen. A. W.
Greely. — Henrietta Nesndth glacier. — Reports by Lieutenant Lockwootl and Sergeant
Brainard. — Mer de Glace Agassiz. — " Chinese Waiy

Greenland

Extent of continental glacier. — Character of the interior. — Elevation of central part of
the ice sheet. — Characteristics of the margins of the Inland ice. — Observations of Lieu-
tenant I'eary near Disco island. — Hunil)oldt glacier. — Observations by Dr. Kane on the
west coast. — Observations by Dr. Xansen on the east coast. — Reports of Lieutenant
Lockwood and Sergeant Brainard concerning glaciers in the north of Greenland. — Cape
Britannia. — ExploTations of the interior. — Baron Xordenskiold. — Lieutenant Peary. —
Christian Maigaara. — Dr. Nansen. — Importance of the study of Arctic glaciers. —
Observations by Chamberlin.

131
131

133

CONTENTS.

CHAl'TKU VIII.

PAOE

Climatic Changes iNUiCATKi) in tiik (;i.a. ikiis ok Nohiii AMEmtA . . .140
(;i.«ra.-t.T <.f tlu< ..vl.l,.„,.,.._u.,v,r,lH of n-oei.t reocMloii In tlio glacleri of (•Hllfornla.
Or^-go... an.l WiuihlnKt..,,. - HrltlM. (oh.mblfi. - .\la«ka. - <lr..ei.l«n.l. - W.-IkIu ..f the
evl.lence.-CUiiiatle ol.aiitft'H iiHllcHt.Mi l>y H,.. glaficrn of the NorthtTii llfiiii»i.lierv .
THE«>HETI( AI. C'ONSIUEHATIONS ,rQ

Influence of dt'brls on the ««lvBn<'.- and retreat of glaciers. *

CHAPTEH IX.

How AND VVllV Gt.A( IEI18 MoVK .

• • • . .

The nature of glueial Mow. — (Jl)8erv;.tlons by Koch and Ktocke.

IIVI'OTHEHEH OK (il.ACIAI, MoTION

The «1I.11„K hypothenlH. _ '• In, SauMure'B theory." - The hypothesis of .Ulatatlon.- The
hypothesm o pla«tl.-lty. -The hypotlu-Kin of r-Melation. - The hypotheniH of expannlon
an. eontiuetlo..._The hypothe«m of Ihiuefaction un.ler prtxHure. - T!... hypothesis of
molecular change. -The hypothesis of granular change. - Observations l.yT. V. Cham-

An Eclectic Hvpothesis

Summary of the properties of lee.
eclectic hypothesis.

■ Sunnnary of glacial »>henoniena. — Authors ot the

100

103

186

CHAPTER X.

The LirE History of a Glacieu

Periods of growth and decline. - The ano«- line. - Spheroid of 32«. - Birth of a glacier -
i)evelopM.ent. - Moraines. - Marginal lakes. - Ice casca.les. - Widening and tlattening of
moraines.- Buried forests. - Forest-covered moraines. - Debris pyramids. - Stran.led
lateral moraines. - Polished and striated surfaces. - Terminal nu.raines. - .Moralne-
damme.1 lakes. - Kock-basin lakes. - l>eath of a glacier. - Climatic cycles. - Pleistocene
Ice sheets.

Concluding Note
Index

190

. 206
. 207

l-AOK
. 1-IU

. 160

ili.u8tratio:n^s.

-aoJOJoo-

100

103

186

. 100

206
207

P.,ATK

it
(I

SKETcir Mai- of North AMEiiifA

Fi<i. A. — MoivT Dana Gi-a( ieu, Cai.ifoknia

10.

11.
12.

•' 13.

" 14.

♦• 16.

-' 10.

PAflK

Frontispiece

NA Gl-A( IEU, CaMFOKNIa )

Fk;. H. — M,„NT LvELL Glacieh, Calikohnia ) ^

MoiNT Lyei,l, Camkohnia

MoiiAiNAL Kmhankmenth, Bu)of)v CaSon, Califok.ma

Sketi II Mai- of Moint Shasta, Camfoiima

F„j. A. — Whitney Glacieh, Moi:nt Shasta, Camfohnia,

Fkj. JJ. — Summit or Moi;.nt I{aime«, WAsiiiNoroji

Sketch Map of Mount Kainiek

Fio. A. — Surface of Cowmtz Glacieh, Mount Rainieh
.Fig. B. — Ice Cave at the Eni. i Nisijuallv Glacieu, Mount Raimei.:
(Fig. a. — Summit of Mount Baker, Washington
|Fig. B. — Cuevasses, Illeceli.ewaet Glaciek, Canada

jFlO. A. — iLLECELLEWAEl Gl.ACIKIt, SELKIRK MOUNTAINS, CaNADA i

/Fuj. B. — Side View of Illecellewaet Glacier J

NoRRis Glacier, Taku Inlet, Alaska

Map of Muir Glacier, Alaska

(Fig. a. — Ice Cliff at thk End of Muih Glacier )

(Fig. B. — Ice Cliff OF Muir Glacier AT Low Tide)

jFio. A. -Surface of Mum Glacier, with White Glacier, a Tributary,

(Fig. B. —Buried Forest at the End of Muir Glacier

17.
18.
19.
^0.

21.

(Fig. A. — HuDRARD Glacier, Disenchantment Bay, Alaska)
I Fig. B. —Glaciated Rocks, Haenkb Island, Alaska {

(Fig. a. — Surface of Seward Glacier, Alaska
{Fig. B. — Davidson Glacier, Lynn Canal, Alaska
Sketch Map of Mount St. Elias Region, Alaska
Front of Malaspina Glacier, Alaska
Central Portion of Malaspina Glacier, Alaska
Malaspina Glacier, from the Chaix Hills . . . .
(Fig. A. — Moraine-covered Border of Malaspina Glacier)
/Fig. B. — Entrance to Tunnel in Malaspina Glacier J

(Fig. a. —Bryant Glacier, Greenland
|Fio. B. — Tuktoo Glacier, Greenland

42
62
66

04
(iO

78
80

. 84
88
!»4

100

108
110
112
118

124
142

X ILLUSTRATIONS.

PAOB

FionnE 1. Ideal Sketch Map of an Alpine Glacier 7

" 2 Drllilin _ 25

" 3. Glacier Tables, Parker Creek Glacier, California . . . 44

" 4. Ice Pyramids, Mount I yell Glacier, California 45

" 6. Iceberg, MuiR Inlet, Alaska .83

" 0. Section OF THE End OF A Tide -WATER Glacier. (After Keid.) . . 85

7. Section OF THE End OF A Tide -WATER Glacier^ (After Russell.) . 86

8. Side View of a Medial Moraine on Muir Glacier, Alaska . . 88

" 9. Lakelet on Malaspina Glacier, Alaska 116

" 10. Grain of Glacial Ice ' ^ ^ I75

I am especially indebted to the Director of the U.S. Geolofrical Survey for the electro-
types used in reproducing the illustrationa forming Plates 3, 4, 6, 1 7, 18, 19, and 20. Other
acknowledgments for sim'lar favors will he made m advance

I. C. R.

GLACIERS OF NORTH AMERICA.

o>tioo-

CHAPTER I.

INTRODUCTION.

It iriay be said of glaciei-s in general that, Lhey are bodies of ice formed
by the accumulation and consolidation of snow in regions where the
snowfall for a series of yeai-s is in excess of the amount melted and that
they flow to regions where waste exceeds supply.

While a typical glacier is easily recognized, and there is no dissent
from what is commonly undei-stood by the name applied to bodies of flow-
ing ice, yet the limitations of the term are indefinite. A type may be
chosen, as the well-known Mer de Glace, Switzerland, for exam{)le, in
which most of the characteristics of glaciei-s are exhibited. Other ice
bodies are known, however, equally deserving to be classed as glaciers,
that are markedly different from such a typco The vast ice sheet of
Greenland exhibits a great departure from the ice streams of Switzerland
in certain features ; while the small ice bodies in the Sierra Nevada,
California, present minor vacations in other characteristics. In both of
these illustrations, and in many others equally at variance with the type
chosen, the term glacier is as appropriate as in the case of the ice stream
on the border oi the Vale of Chamounix.

The difficulties in determining the limitations of the term glacier may
be illustrated by the use of the word river. When does a stream cease to
be a brook, or a creek, or even a lake, since many lakes are but ♦expan-
sions of streams, and reach the dignity of a river? In a similar way, it
is difficult to decide when an accumulation of snow acquires sufficient of
the characteristics of a typical glacier to be included in the same class ;
or again, when a glacier loses motion and becomes a stagnant ice body,
when it shall ce?^se to be known by tiie title it ea'-ned when it was au
avenue of ice drainage.

GLACIERS OF NOIiTH AMKKICA.

In instances where the conditions are indefinite or peculiar, only an
arbitrary decision can, perhaps, be reached ; but usually the presence or
absence of a number of the commonly recognized characteristics of typi-
cal glaciers is sutlicientiy pronounced to exclude controversy.

11'

Leading Characteuistics of Glaciers.

Mode of Accumulation. — The formation of glaciers in any region
depends primarily on climatic conditions. When the climate is such that
the amount of snow falling for a term of years is in excess of the amount
melted, evaporated, or blown away, perennial snow banks are formed, the
more deeply buried portions of whir a become compacted into ice. The
change i.om snow to ice is known to r3sult from pressure and from par-
tial melting and refreezing. Many observations have been made which
show that normal glaciers liave a characteristic flowing motion. The
material of which they are composed is drained from regions of
accumulation in much the same manner as rivers drain areas where
the rainfall exceeds evaporation. This process of ice drainage relieves
areas of heavy snowfall from their burdens, and prevents indefinite
accumulation.

Three Tj'pes of Glaciers. — For convenience of reference the glaciers
nov/^ known may be arranged in three classes, namel}', alpine, piedmont^
and continental. These three classes are not always distinct and clearly
sejjarable, but typical examples of each may be selected that are well
characterized, and dilfer in essential features from typical examples of each
of the other classes. In each group there are conspicuous variations
which suggest minor or more specific subdivisions.

Of the three great classes referred to above, the most widely known is
the alpine type, which derives its name from the mountains of central
Europe, where it was first studied. Alpine glaciera occur about high
peaks and on the summits and flanks of mountain ranges in many parts
of the world, but reach their most perfect development in tempernte
regions. The Himalayas, the Alps, the mountains of Scandinavia, the
Southern Alps of New Zealand, the Cordilleras, etc., furnish well-known
examples. Glaciere of this type originate as a rule in am[)hitheatres and
cirques, partially surrounded by lofty peaks and oversiiadowing preci-
pices, and flow through rugged valleys leading from them as winding
ice rivers which carry the excess of snow falling on the mountains to

INTUODUCTION.

lower regions, where a higher mean annual temperature causes it to melt.
They are essentially streams of ice, formed usually by the union of many
branches, and end aljruptly when the drainage changes from a solid to a
liquid form.

(ilaciers of the piedmont type are formed where alpine glaciers leave
the rugged defiles through which they flow and expand and unite on an
adjacent plain. They may be considered as analogous to lakes, for the
reason that they are fed by tributary ice streams. The influx of ice is
counterbalanced by melting, especially from the surface and borders of
the partially stagnani mass. The chai-acteristics of glaciers of this type
are foreshadowed when individual alpine glaciera leave a high-grade gorge
and expanil in a lateral valley or on a plain. The expanded terminus of
Davidson glacier, on the border of Lynn canal, Alaska, illustrates what
may be take, as the first step toward the formation of a piedmont glacier.
The semicircular or delta-like ice foot of the Rhone glacier, Switzeiland,
v/here it spreads out at the head of the Rhone valley, is a more widely
known, although a comparatively diminutive example of the same char-
acter. If one fancies a score or more glaciei-s of the Davidson and Rhone
type, uniting on a plain and forming a single confluent plateau of ice
many square miles in area, he will appreciate the leading characteristics
of tlie ice sheets termed piedmont glaciers.

A type of the piedmont glacier, and the only one of the class thus far
described, is Malaspina glacier, Alaska, situated at the southern base of
Mount St. Elias and neighboring mountains, from which it is nourished
by many ice streams. This magnificent ice sheet covers an area of 1500
square miles, and is from 1000 to 1500 feet thick. West of Malaspina
glacier, and occupying a plain intervening between high mountains
and the sea, is another piedmont glacier, knovai as Bering glacier,
which is of the same general character as its companion, but has not
been explored.

Ice bodies of the third class, as their name implies, are of vast extent
and may even cover entire continent'^. Existing examples are confined
to Greenland and to Antarcti' regions. Others that have now vanished,
left unmistakable records over large portions of northeastern North
America and northwestern Euroije. The principal characteristics of con-
tinental glaciers are their vast extent, their comparatively level surfaces,
and the prolongation of portions of tb.eir Iwrdei's into lol>es and even
into well-defined streams, where the topographic and other conditions are
favorable.

4 GLACIEHS OF NOKTH AMERICA.

On comparing the three classes of glaciers just enumerated, one finds
that alpine glaciers, when well developed, appear as trunk streams formed
by the union of many branches. ^ They usually flow through narrow
valleys froii higher to lower regions, and end abruptly in precipitous
walls of ice or expand at their extremities and terminate with low frontal
slopes, according to local conditions. In many ways they are analogous
to rivers. Piedmont glaciers receive many tributaries of the alpine
type, are not confined by rocky walls, and do not have the well-defined
stream-like flow exhibited by glaciers descending narrow valleys. Tney
are only moderately lobed, do not send out well-defined branches, and are
in part stagnant, ice masses. Their nearest counterparts in ordinary water
drainage, as already mentioned, are found in lakes fed by mountain
streams. Continental glaciers are without tributaries, their broad surfaces
forming the necessary gathering-ground for snov/ accumulation. Their
margins may be strongly lobed, or even send out well-defined tongues of
ice, but the area of ice extending beyond the margins of the central snow
field is in existing examples comparatively small.

Each of the three types of glaciers here enumerated is represented in
North America, and their characteristics and distribution will be described
in the following chapters.

N6v6 and Glacier Proper. — Glaciers of the alpine type, and in a
less marked way those of the continental type, have their surfaces
divided into two portions, a nev6 or snow region above, and an ice portion
below. The lower portion has no specific name, but is frequently desig-
nated as the "glacier proper. " The line of demarcation is the snotv line,
i.e. the lowest limit of perennial snow. As compacted ice occurs also
directly beneath the n^v^ from which it is formed, this division of a
glacier into two portions applies only to the surface. Moreover, the
position of the dividing line is subject to secular variations. At times,
possibly for many consecutive years, in the case of small glaciei-s, the
snow may completely cover the true ice, so that one might Avalk over the
accumulation and easily mistake it for the snows of a single winter, and
be led to conclude that it was not entitled to be considered as a member
of the great family of glaciei's.

The n4iv6 is composed of str.atified granular snow which is white or
grayish white in color. The snow on high mountains is apt to be exceed-
ingly fine, light, and dry when first formed ; but by partial melting and
ref reccing it acquires a coarae, granular texture, much like compacted hail,

INTRODUCTION.

and also becomes consolidated and hard. The surface of the n6y6 is many
times so softened l)y the warmth between summer storms, that a thin crust
of ice is formed when the temperat'ne is again lowered. 1'his crust is
buried beneatli the next succeeding snowfall and remains in the growing
deposit as a thin stratum of ice. Ndves are almost entirely free from
stones or dirt, although even on the highest mountains, the dust borne
from naked cliffs is widely spread over their surfaces and diminishes their
brilliancy. This general dust-covering is frequently not noticeable until
some really clean snow surface is brought in contrast with it. Whcit u lake
on the n6y6 is drained and leaves a fresh surface of dazzling whiteness, the
surrounding area frequently shows a gray tint by contrast, thus revealing
tlie presence of dust which has been sprinkled over it. Sometimes thv.
covering of dust, especially on the lower portions of the n(;v(is of alpine
glaciers, is sufficiently pronounced to form a definite division plane when
buried by subsequent snoAvfalls. Illustrations of such an occurrence may
frecpiently be seen in the walls of fissures. In the great open fissures or
crevasses that bre'^-k the ndv^s in the region about Mount St. Elias, a
dozen more or less distinct strata separated by bands of blue ice, a fraction
of an inch thick, or by still more conspicuous dust-stained layers, may be
frequently counted. In some instances the layei-s of granular snow are
fully fifty leet thick, even after having passed from the light, mealy
consistency of freshly fallen snow to the much more compact condition
of the granular n<?v6 snow, thus indicating the abundance of the snow-
fall in the regions where glaciers have their birth. The surfaces of
n6\6s are renewed many times during the year by fresh snow. Stones
and dirt falling on them from surrounding cliffs, or swept down by
avalanches from tributary slopes, are buried from sight and enclosed in
the growing deposits.

Below the snow line, the true glacier, composed of compact ice, makes
its appearance at the surface. The horizontal stratification so well marked
in the n^v^ is nearly or quite obliterated, but the ice takes on a character-
istic bant'ed structure, due to alternation of thin sheets of clear, blue ice
with sheets of vesicular, white ice. As has been shown by laboratory
experiments as well as observations on glaciers themselves, this peculiar
banded or ribboned structure is caused, in part at least, by pressure, and is
analogous to the slaty cleavage observable in certain rocks. At the lower
extremities of glaciers in many instances the banded structure is obscure,
or ijerhaps entirely obliterated, and the ice presents a coarse, granular
appearance not unlike the grain oi crystallized marble. As will be

GLACIERS OF NORTH AMERICA.

explained, this " glacier grain " is not confined to the extremities of
glaciei-s, but has been recognized throughout the extent of the glaciers
proper.

The ice below the snow line is frequently dirt-stained and more or less
completely covered with angular stones and large jock masses. This
superficial covering is so general on many glaciers that from a distance no
traces of ice can be seen, and they appear as dark and barren as a newly
plowed field. In a general view of a snow-covered mountain range the
two surface divisions of the glaciers on its sides are usually distinctly
shown by coutnist in color. The higher or neve portions are white and
glistening, while the lo'ver portions either reveal the blue tint of compact
ice or are dark with earth and stones.

The debris that falls on a neve from bordering cliffs, and the dust blown
over its surface, sink into the soft snow, principally on account of the
absorption of heat owing to their dark color, and are buried by later snow
storms. As the neve becomes consolidated and acquires motion, this
debris is carried along within its mass. In the region below the snow-
line, however, where the annual melting exceeds the annual snowfall,
the surface of the ice is liquefied, and foreign substances previously buried
become concentrated at the surface. The tendency of the neve is to bury
foreign objects, and of the glacier proper to concentrate them at the
surface. For this reason the lower and consequently the more wasted
portion of a glacier is the more thoroughly dirt-covered.

"fi:

Moraines. — All of the debris carried by glaciers may be designated
in general as morainal material. When arranged in certain more or less
definite ways it is known under specific names. When distributed along
either margin of a glacier it forms lateral moraines. When two glaciers
unite, the right lateral moraine of one of the branches joins the left lateral
moraine of its companion, thus forming a medial moraine in the central
portion of the compound glacier below the junction. When a trunk
glacier is formed by the union of several branches, as is frequently the
case, the number of parallel lines of debris on its surface is correspond-
ingly increased, being always one less than the number of well-defined
branches that unite to form the compound stream. This nomenclature
will be better understood by referring to the following ideal sketch map
of the surface of an alpine glacier, formed by the union of four tribu-
taries. The moraines on the surface of the ice are shown by dots and
the mountain slopes by sketch contours.

INTKODUCTION.

The debris carried to the end of the glacier and deposited about its
extremity, in some cases forms a crescent-shaped ndge, known as a
terminal moraine. Simihir moraines about the margin of piedmont and
continental glaciers are usually designated as frontal moraines; when two

Pig. 1. — Ideal sketch Map of an Alpink Olaciee, showing Lateral, Medial,

AND TEUMINAL MoHAINES.

I lobes on tbe outer margin of such glaciers unite, the debris deposited
lalong the i. le of junction forms interlobate moraines. Moraines are
isubglacial, englacial, or superglacial according to their position.

Other somewhat technical terms used to designate various modifi-
[cations of morainal deposit will be explained in treating of glacial
records.

Crevasses. — Moving ice masses, especially when flowing over rough

Surfaces or through rugged valleys, are subjected to stresses which cause

(them to break and fissures to open. Such open fissures were termed

revasses by Swiss mountaineers, long before the attention of scientific

len had been called to them. The name has been adopted by glacialists

a general term for the gaping fissures that so frequently break the

GLACIEU8 OF NOKTH AMEKICA.

surfaces of moving ice masses. Crevasses occur both in n6v^s and in
true glacial ice, and present varying characteristics which have led to a
somewhat specific classification.

The snow fields at the heads of alpine glaciers are frequently
traveled by fissures several hundred feut long and varying in width
up to 50 feet or more. They are widest in the central [)()rtion, and
taper gradually to mere cracks at their extremities, wliich are frequently
curved in opposite directions. Even the greatest crevasses are at first
simple or compound fractures, too narrow to allow one to insert the
thinnest knife blade, and slowly open in the course of weeks or months.
This widening of crevasses, especially in neves, is due to the stretching
of the material that they travei'se. It is frequently stated that ice,
though jjlastic under pressure, yields to tension only by rupture. The
slow o[)ening of crevasses by the widening of their central portions,
certainlv indicates, however, that ice, when subjected to slowly acting
tension, does stretch to some extent without fracture.

As stated above, crevasses begin as narrow cracks and gradually widen.
While camping on the broad neves in the Mount St. Elias region, my
attention was frequently called to the formation of these breaks in the
ice. On one occasion, while sleeping in a tent far out on the neve of the
Agassiz glacier, I was wakened several times during the night by rum-
bling sounds accomjjanied by sharp crashes, which seemed to proceed
from the ice immediately beneath our tents. With each crash the ice
trembled and vibrated as if an earthquake wave had passed through it.
The sounds came so suddenly and were so startling that some of my
party who were not familiar with the behavior of glaciers, rushed from
the tent in considerable alarm, fearing that a crevasse was about to yawn
beneath them. In the morning we found that a crack in the ice, several
rods in length but without appreciable width, had formed immediately
in front of our tents.

The walls of crevasses in n^ve regions are of the most exquisite
turquoise blue, the color deepening below the surface until it seems
almost black. The only color in nature that rivals the blue of glacial ice.
is seen ^vhen one looks down into the unfathomable sea. The sides of
crevasses are frequently hung with icicles, forming rank on rank of
glittering pendants, and fretted and embossed in the most beautiful
manner with snow wreaths, and partially roofed with curtain-like cornices
of snow. These details are wrought in silvery white, or in innumerable
shades of blue with suggestions of emerald tints. When the sunlight

INTHODUCTION.

s and in
led to a

■equently
in width
tion, and
tequently
e at tirst
nsert the
r months,
itretching

that ice,
ire. The

portions,
/ly acting

lly widen,
■egion, my
iks in the
eve of the
t by rum-
D proceed
h the ice
hrough it.
me of my
ished from
it to yawn
ce, several
imediately

■m

enters the great chasms, their walls seem encrusted with iridescent
jewels. The still watei-s with which many of the gulfs are partially tilled,
rertect every detail of their crystal walls and make their depth seem
infinite. No dream of fairy caverns ever exceeded the beauty of these
mysterious crypts of the vast cathedral-like amphitheatres of the silent
mountfiins.

Encircling the upper bordei-s of the nev6 in most snow-filled amphi-
theatres, there is a great crevasse or a series of nearly parallel and
intersecting fractures that differ in certain ways from the crevasses formed
lower down. The most rapid motion in a n^ve probably occurs deep
below the surface, where the p ;ssure is greatest and the ice compact. The
light snow forming the surface of the nev6 is carried bodily forward by
the flow of the ice on which it rests ; this together with the general settling
of the newer and more incoherent snow causes it to break away from the
f:urrounding cliffs, (ireat open fissures are thus formed, which border the
upper margin of the n^ve and separate it from the rocks above in
such a manner, in many instances, as to offer an impassable obstacle.
These breaks frequently mark the boundary between snow work and
rock-climbing, and are known as heiyschnimh, or mountain crevasses.
Break . of this character are among the very first to form when an amphi-
theatre becomes snow-filled, and continue to appear at the same localities
as the glacier advances in age. They occur close to the bordering cliffs
but leave portions of the neve, frequently several rods broad, still clinging
to the rocks. A bergschrund, in the majority of instances, is of the nature
of a fault. The snow left attached to the rocks and forming the upper
margin of the crevasse stands higher than the opposite margin of the
fracture. The snow forming the thrown block, has been affected by a
downward movement, and also by a horizontal movement which opened
the fracture. In observed instances, the vertical displacement is from a
few inches to fifty or sixty feet or more ; and the horizontal movement
shown by the breadth of the crevasse, frequently from fifty to seventy-five
feet. At times compound, or step faults, as a geologist would call them,
are formed and two or more nearly parallel crevasses break the surface.
In winter these breaks are filled and a new layer is added to the surface
of the ,n6ve, but during the succeeding spring they form again in about
the same position as the year previous.

In the breaks encircling the head of a neve, the rock beneath the snow
left clinging to the mountain is usually exposed and becomes greatly
shattered by frost and changes of temperature. The blocks thus loosened

GLACIERS OF NORTH AMERICA.

are plucked oft the succeeding year, when another crevasse forms in the
same locality. It is thought by some students of topography that the
waste from these exposed surfaces leads to the growth of amphitheatres
and cirques and explains many of the peculiarities in the relief of
glaciated mountains.

When a glacier descends a precipice it may become broken find fall in
detached blocks, thus forming veritsible ice cascades; but the fragments
unite again at the base of the cliffs and become reconsolidatcd, and the ice
flows on as a continuous stream. At other times the descent is completely
covered with ice so shattered as to be impassable, and presents all degrees
of diversity between ice cascades and ice rapids. The places of steep
descent in the floor of a n^ve frequently lead to the breaking of the snow
and ice into cubical blocks of all dimensions up to hundreds of feet in
diameter, which bear a striking rese mblance to towers and other architec-
tural forms, and add most attractive features to the scenery of glacier-
covered regions. During night marches on the glaciers of Alaska, the
writer could scarcely put aside the idea that these shadowy forms par-
tially illuminated by the r|orthern twilight, were in reality the ruins of
marble temples. In the lower portions of glaciers, where the ice is more
solid and where surface melting is more rapid, the steep descents are
marked by spires and pinnacles having extremely rugged and angular
forms, separated by profound crevasses. These true ice falls are much
more rugged and much more difficult to traverse than similar descents
in the n6v6, and are seldom accessible even to the most experienced
mountain climbers.

When a glacier passes over a moderate inequality in its bed, it is
fractured so as to form crescent-shaped fissures which are widest just
below the obstruction and gradually close as the slowly moving stream
flows on. In pas^nng over such obstructions the surface of a glacier,
especially in the n6v6 region, sometimes rises so as to have a buekward
slope. Instances of this nature have been observed in the neighborhood
of Mount St. Elias. Marginal crevasses are formed on the sides of well-
defined glaciers, owing to the friction on the sides and the more rapid
flow of the central portion. These breaks trend up stream at angles of
approximately 40°, and are broadest at the shore. When the banks of an
ice stream are of snow and ice, counterparts of the marginal crevasses
are formed in them and trend down stream, and are practically continuous
with the breaks in the margin of the glacier itself. The marginal
crevasses in the glacier and the similar breaks in the adjacent bank,

INTUODUCTION.

rms in the

Y that the

)hitheatre8

relief of

ancf fail in
fragments
and the ice
completely
all degrees
8 of steep
f the snow

of feet in
3r architec-
of glacier-
Alaska, the
forms par-
he ruins of
ice is more
escents are
lid angular

are much
ar descents
ixperienced

bed, it is
widest just
ring stream
■ a glacier.
I bi-ckward
ighborhood
ies of well-
more rapid
it angles of
janks of an
,1 crevasses
continuous
e marginal
,cent bank.

however, are separated by a band of shattered snow sometimes several
rods b'-oad, which sharply defines the margin «>f the current. These
crevassed banks of snow and ice are common in the St. IClias region, and
have been d'scrilxjd by tlie writer.*

In the ciise of glaciers that expand on leaving narrow volleys, stresses
are produced in other directions than in the cases cited above, and longi-
tudinal or more or less regularly radiating breaks are produced. A well-
known instance of this nature is furnished by Rhone glacier.

It may be judged from this brief sketch that the conditions leading to
the fracture of moving ice masses uro exceedingly varied an«l pro(hice
diveree results. The series of more regularly arranged fractures, to which
special attention has l)een directed, are united by other and less easily
explained breaks, so that the detail of the surface of an ice stream, espe-
cially when modified by melting, becomes at times wondeifuUy complex.
It is only by selecting isolated and well-defined instances for study that
the laws governing the behavior of ice under the varied stresses produced
in flowing through irregular valleys and over rough surfaces can be at all
understood.

The ice of glaciers is also broken along planes more or less inclined to
their surfaces. Movement takes place along these breaks, and produces
thrusts, analogous to the over-thrusts, or under-thrusts, sometimes seen
in rocks that have been folded and broken. In fact, the counterpart of
many of the structural features observed in rocks, such as faults, folds,
joints, contortions, etc., may be observed in the ice of glaciers.

Surface Features. — Owing to the presence of crevasses and to unequal
melting, the surfaces of glaciei-s are frequently exceedingly rough and
irregular. Foreign matter resting on the ice, when sufficiently thick not
to be warmed through by the sun's lieat in a single day, protects the ice
beneath, while adjacent surfaces not so protected are lowered by melting.
Blocks of stone thus shelter the ice beneath and remain on i)illars or ped-
estals as the surrounding surface is lowered. A group of such " glacier
tables," as they are called, is shown on page 44. Tliese were observed
by the writer on a small glacier on the High Sierra of California, and
present a fair idea of the character of the mushroom-shaped prominences
common on many glaciere. Glacier tables frequently incline southward
in north temperate latitudes, owing to the greater melting of their sup-

1 "An Expedition to Mount St. Ellas, Alaska," National Geographic Magazine
(Washington, D. C), vol. 3, pp. 127, 128.

GLACIERS OF NOKTU AMERICA.

poitinp columns on tho Houth side. Eventually, the uprawed block slips
off its pedestal in a southerly direction, leaving a stunij) of ice to mark
its site. When this happens, the process is renewed and the hlock aj^ain
left in relief by the meltinpf of the surrounding surface. 'J'lie boulders
and stones carried on the surface of glaciei-s thus receive many falls,
and Inicome broken and more or less comminuted. This illustrates the
fact that not all of the crushing and commingling of rocks performed by
a ghuuer takes place deep within or beneath its mass.

Moraines on the surfaces of glaciiei-s are composed in a great measure
of blocks of stone, whic^h protect the ice beneath, as stated above, and
produce still more marked ine<iualities of the surface. What appear to
be massive embankments of ."tones and dirt are many times ridges of ice
covered witli a veneer of debris only a foot or two thick. The slow melt-
ing of the ice beneath superficial moraines causes the larger and less
angular stones to slide and roll down the sides of the ridges, thus lead-
ing to a rude assortment of the material, with reference to size and
sliJipe. Sudi an assorting may l)e seen in the side view of a medial
moraine shown in Figure H. Tiie friction and impact of the frequently
disturbed roctks cause breakage and the formation of angular gravel, and
even clay. Disintegration and weathering are thus j)romoted, and the
surface material becomes divided into smaller and smaller masses the far-
ther it is carried or the longer it remains on the ice.

When there are several i)arallel moraines on a glacier the surface
becomes exceedingly rugged ; and when, in addition, creviisses cross
such a region, it is frequently rendered entirely impassable. I well
remember a long, weary march across the Malaspina glacier, when our
route lay at right angles to fully a score of huge moraines, each one
forming a ridge from 50 to 200 feet broad at the top, and rising 100 or
150 feet above the adjacent troughs. These ridges were completely
sheathed with stones held in sockets of ice, which would frequently slip
from beneath our feet and roll to the bottom of the escarpment. The
sides of these ridges were so steep that we could ascend them only by
choosing zigzag courses. Many were the slips and tumbles experienced
during the day. Between the ridges that caused so much delay and
fatigue, there were lanes from a hundred to several hundred yards broad,
floored with comparatively smooth ice, which, had been deepened by the
melting of the glacier, where unprotected. When standing on the crests
of the dark, stone-covered ridges one could trace their courses for miles
on either har d, until a change in the slope of the glacier carried them

INTKODICTION.

the surface

out of view. At rij?ht angles to tiieir tren<l there was nothing in
Hi^ht except the (llHtaiit niountaiiiH und the Heeniingly eiullesa expunse
of hiirrtiii and exceedingly desolate dehris.

MaHses of sand and gravel renting on ice behave in nnu-h the same
manner as <lo rock masses and moraines, except that wln^re they are left
upraised alK)ve the wasting surface the grains and pebhles roll ami slide
downward, and the pedestal is transformed into a cone of ice sheathed
with a thin covering of loose njaterial. At times, many acres far out
on a glacier, are studded with groups of these peculiarly regular cones
or pyramids, from a few inches to ten or twelve feet in height. Not
infrecpiently tluy lH»ar a striking resemblance to Indian tei)ees ; in fact,
one might easily mistake a group of these structures for an Indian en-
campment.

Still greater inecpialities occur when moraines rest on stagnant ice and
basins holding lakelets are formed. The sides of these depressions melt,
and the stones and dirt previously spread out as a general morainal cov-
ering over the surface fall into them. The surface material thus l)ecome8
locally concentrated. As melting progresses, the lakes are drained.
These thick accumulations of debris protect the ice beneath and become
elevated in the same manner as the sand cones descriljed above; but the
mass of the material being greater, and frequently containing large boul-
ders, the cones fc»rmed are of large size, and in many instances have an
elevation of i)0 to 150 feet. Although looking like pyramids of rudely
piled bouldei-s, one finds on climbing their sides that they are really
pyramids of ice with a comparatively thin sheathing of stones and dirt.
Large bouldei-s, i)erched on the summits of these rugged ]>yramids,
become detached from time to time, and descend in small avalanches to
the depressions below, illustrating, again, the process of breaking and
disintegration which takes pLice in the debris covering the surfaces of
glaciera.

While large rocks or thick masses of dirt and stones resting on ice pro-
tect it from melting, the reverse is the case Avith pebbles and other small
objects, particularly those of a dark color, which become Avarmed through
by the sun's heat during a single day, and lead to the melting of the ice
beneath. Such bodies sink into the ice and are commonly found at the
bottoms of little water-filled wells five or six inches deep. On glaciers,
where there is a scanty covering of pebbles, each individual stone will
be found at the bottom of a water-filled depression. Sometimes the
holes are so abundant that in walking over the surface one really treads

GLACIERS OF NORTH AMERICA.

on the summits of thickly set columns of ice, separating the depressions.
Leaves are frequently blown far out on glaciers, and becoming warmed
by the sun sink into the ice in the same manner as the pebbles already
refeiTcd to, and even insects, especially butterflies, are conspicuous in
such localities. Op one occasion, when traversing an ice stream tribu-
tary to Malaspina glacier, I found a fish, about four inches long, at the
bottom of one of these holes. The nearest water in which it could have
lived was at least twenty miles away. The most probable supposition is
that it had been carried to the place where found by a bird.

iijli
ill

Meltin§r and Drainage. — The silence on broad glaciers when the winds
are still and the temperature below freezing is frequently oppressive.
This is especially noticeable on summer nights, for after sunset even in
summer the teiaperature falls below freezing on the surfaces of large
glaciers ; but when the morning sun warms the air, rills and ri v^ulets are
formed, a'.id the murmuring of running water is heard on every hand.
By midday, brooks and creeks, too deep and rapid to wade and too broad
to vault over, are coui'sing along In channels of ice. But their exist-
ence is brief. Soon a crevasse is reached, and their floods pour down
into the depths of the glacier with a deep roar, telling of caverns far
below the surface. The crevasses into which surface streams find their
way are frequently enlarged, and become well-like openings, or moulina,
as they are termed, which are sometimes several yards in diameter, and
of great depth. In many instances, these openings must penetrate to
the very bottom of a glacier. When this happens, the bould'^"3 and
stones that find their w. into them are washed about, and are given
a rotary motion by the descending waters, so as to act as veritable mill-
stones, and grind the rocks beneath. The result of this action is the
formation of pits and holes in the rocks, resembling kettles, and termed
pot holes, in which the stones that made them may frequently be found.
These peculiar excavations are Avell known in regions of former glaci-
ation. Typical examples in the Glacier garden, near Lucerne, Swit-
zerland, are familiar to many.

The surface melting of glaciers leads to the formation of broad, shal-
low lakes. These appear especially on the neves, and by the intensity
of their deep blue color impart an additional charm to the wintry scenes
reflected from their surfaces. The chores of such lakos afford favorable
camping places for glacier explorei-s, since water, the only necessity of
camp life to be found in such regions, can there be had without the

UNTKODUCTION.

expense of time and fuel necessary to procure it by melting snow.
Many times during two expeditions conducted by the writer on the
broad n6\e fields of southern Alaska, we had occasion to pitch our
tent by the shores of these snow-bound Lakes, and fully appreciated the
advantages they afforded. In other instances, when necessity required
us to camp on greatly crevassed snow, our water supply was bometimes
obtained from the crevasses by means of a bucket attached co a line.

tf he water formed on the surfaceii of glaciei-s, and draining from the
land surrounded by them, or lying in front and sloping to^^ irds them,
finds its way into the ice and escapes by tunnels situated either at the
bottom of the glacier or in the ice itself. At the ends of alpine glaciers,
and about the margins of both piedmort »rd continental ice sheets, there
are ice caverns from which flow turbid streams of ice-cold water. (Fig. B,
Plate 17.) The archways are the mouths of tu.^ne^" into which one
can sometimes penetrate for a long distance. The sti:.ams issuing from
such openings are supplied by both surface and basal melting, and pos-
sibly also by subglacial springs. These tunnels appear in all stages of
glacier growth, and are kept open even when ice sheets reach great dimen-
sions. On Malaspina glaciers, the course of such tunnels csin in some
instances be followed for miles, by listening to the muflBed roar of the
rivers rushing along through »oe caverns far below the surface. Some of
the tunnels, through which the waters formed by the melting of glaciars
escape, are known to be situated on the underlying rock, but in other
instances the openings traverse the ice itself, perhaps several hundred feet
above its bottom. The tunnels through the body of the ice are thought
to have originated from crevo,sses which allowed the surface water to
escape from one break to another, and maintain a continuous passage-way.
But observations proving this to be the true explanation are wanting.
In the sides cf deep crevasses in the Malaspina glacier one some-
times discover a circular openiug several feet in diameter, which reveals
the position of an abandoned tunnel. In traversing the extremely rough
outer margin of the glacier leferred to, these openings were at times
of great assistance, as they allow an explorer to pass from one deep
valley in the ice to another, and thus avoid a steep climb over moraine-
covered ice.

The drainage of glaciers, particularly those of the piedmont and conti-
nental types, is of special geological interest, for the reason that vast
quantities of mud, sand, gravel, etc., are carried into the tunnels through
which the sub- and engJacial streams flow, and either left on the bottoms of

GLACIERS OP NORTH AMERICA..

i ;i

the channels, or swept out at the margins of the ice and deposited in part
over the adjacent land. The sediments now forming about the border of
Malaspina glacier are of great volume, and of more geological interest
than even the abandoned moraines left by the slowly retreating ice mass.
As will be described, thousands of acres of dense forest are there being
overwhelmed and buiied by the deposits of streams, that pour out from
tlie ice, heavily freighted with sediment and even sweeping along large
bouldei-s. *

The chief characteristic of the streams that emerge from beneath
glaciers is their peculiar turbidity or milkiness. In exploring regions
where the glaciers are small and hidden in sheltered recesses about high
peaks, one is frequently enabled to discover them by noting the character
of the waters flowing from the mountains. Upland streams not fed by
melting glaciers are usually clear and sparkling, except during stoiTis,
while those born in ice caverns are rendered opalescent, and have a pecu-
liar greenish-yellow tint, on account of the extremely fine material sus-
pended in them. This fine rock flour, as it is termed, is retcined in sus-
pension even after the streams emerge from the highlands and flow through
adjacent plains. Deposits of fine sediment of peculiar geological interest
are formed by such streams, and enable one to interpret similar accumula-
tions termed loess, left about the margins of ice sheets that have now passed
away, and along the stream channels leading ^'-om them. The bluffs of fine,
yellowish, clay-like material along the Mississippi and Missouri are of this
character. ' ,

What is a Glacier?

The preceding paragraphs contain, I believe, an enumeration of the
principal characteristics of glaciers. Although it is diflicult, and perhaps
impossible, to frame a concise definition of a glacier which will embrace
all ice bodies that should be properly included, and exclude other accumu-
lations of snow and ice to which the name should not be applied, 5^et it
seems safe to assert that any considerable mass of snow and ice which
presents a number of the characteristics referred to above may with
propriety be included in the term.

As a provisional definition, it may be said that a glacier is an ice body
originating from the consolidation of snow in regions where secular accu-
mulation exceeds melting and evaporation, i.e. above the snow line, and
flowing to regions where waste exceeds supply, i.e. below the snow line.
Accompanying these primary conditions are many secondary phenomena

INTRODUCTION.

dependent upon environment, such as the grain of the ice, crevasses, melt-
ing, laminations, dirt bands, moraines, glacier tables, ice pyramids, sand
cones, et(f., which may or may not be present. Glaciers, even of large
size, may exist in which few and perhaps none of these details can be dis-
covered. We may conceive of a glacier as flowing through a channel so
even and so well adjusted to its progress that no crevasses will be formed.
So little debris may reach its surface that moraines and all accompanying
details will be absent. The most persistent features of an ice stream
are, perhaps, the slow movement or downward flow in both the neve and
ice regions, the stratification of the neve, and the laminated structure
and grain of the glacier proper. Yet even these important characteristics
may not be readily discernible, even in ice sheets that are unques-
tionably true glaciers. Although the brief definition given above may
assist one in obtaining an idea of what constitutes a glacier, it is mani-
festly open to qualifications and exceptions. If we consider the snow line
as defining the boundary between the neve and the glacier projjcr, it is
evident that there must be numerous exceptions to the rule. As before
remarked, during certain yeai"s, and at times for many years in succession,
the snow line is much lower than at other times, and may even completely
conceal the hard ice which usually protrudes below the neve. Again, an
ice stream may end in the sea, and be broken off and float away as bergs,
before the division into neve and glacier proper is distinguishable on the
surface. One of the most characteristic features of glaciers is their slow
flowing motion, yet in their old age this may cease, so that the limits
between a true ice stream and an inert ice mass may be indefinite, and
perhaps impossible to define.

From what has been learned concerning glaciers it is evident that they
form »ne of the transition phases in the history of drainage in many
regions, and that the variations they present, like genera and species in
the organic kingdom, cannot be limited by hard and fast lines, but should
be classified by means of comparisons with typical examples. From snow,
hail, and frozen mists, usually on elevated regions, the granular ice-snow
of a neve is formed. By pressure and alternate softening and re freezing
the n^ve is changed into compact glacial ice, but the plane of separa-
tion is indefinite, and no one can say where in a vertical section, the nev6
ends and the true glacial ice begins. Both the neve and the glacier
proper are wasted hy melting when ihe temperature is above 32° of
the Fahrenheit scale, and the solid drainage is transformed to a liquid
co'^dition.

GLACIERS OF NOUTH AMERICA.

'! Ill

;'#

Glacial Abrasion.

■Worn and Striated Kock Surfaces. — The movement of glacial ice
causes friction and leads to the grinding, smoothing, and scratching of
the rocks over which it passes. The intensity of this grinding can be
appreciated to some extent by considering the force with which a thick
ice mass presses on the rocks beneath. The weight of a cubic foot of ice
is about fifty-seven pounds; hence a glacier 1000 feet thick, which is by
no means the maximum, would exert a pressure on its bed of twenty-eight
tons to the square foot. A movement of ice charged with sand and
stones under such a pressure cannot fail to produce abrasion of the
rocks beneath.

As will be shown in a future chapter devoted to theories of glacial
motion, the precise mechanics of glacial flow is not clearly understood.
It is well known, however, that the ice is not forced along as a rigid body.
If such were the case, the grinding would be far more intense than is now
believed to occur. It is, also, known that the flow of glacial ice is at least
analogous to the flow of what are commonly considered plastic solids, as
pitch, for example. In an ice stream the movement is most rapid at the
surface at a distance from its borders, and decreases toward the bottom
and sides, where the friction is greatest. Under similar conditions the
movement of clear ice is greater than when it is charged with ddbris.
The study of glaciers has shown, also, that sometimes the ice is sheared,
and a forward movement is accomplished by a thrust of the upper portion
of the mass over the lower portion. However accomplished, the fact
remains that there is frequently a movement of even the saud-charged
layers at the bottom, and that friction does occur between the ice and the
underlying rock.

The conditions governing the flow of glaciers are so complicated that
varying results are to be expected. When the bottom layer is heavily
charged with debris, and, especially when containing a large proportion
of gravel and stones, the friction is increased, and may possibly become
so great that the bottom layer will be practically stagnant and allow
the clearer ice above to flow over it ; or a shearing of the mass may
result, and the lower portion remain stationary for a time, while the
upper portion moves on. Probably the mo&t favorable conditions for
rock abrasion are when the bottom of a glacier is lightly charged with
sand, and the surface of contact with the rocks beneath is lubricated with
water. That glaciers abrade the rocks over which they pass, as already

til

INTRODUCTION.

stated, there is abundant evidence. At the lower end, and along the
[sides of many alpine glaciers, the ice charged with sand and stones may
be seen in direct contact with the smooth, polished, and striated rock
surfaces. Below glaciers that have recently retreated, and where the
surface is still bare of vegetation, records similar to those jubt mentioned
may be observed in thousands of localities. The same is true, also, over
vast regions that are known to have been formerly glaciated ; \*hile on
adjacent areas, where the c nditions are similar, excepting that they were
not occupied by ice, the peculiar and not easily mistaken evidences of ice
abrasion are lacking. vVe have, therefore, both positive and negative
evidence pointing to the conclusion that glaciers abrade the rocks over
which they flow.

Smoothed and Stria teu k Surfaces not Produced by Glaciers. —

There are markings that simulate glacial polishing and striation, an '.
might be mistaken for them, but are produced by other agencies. River
ice, especially when swept along by freshets, sometimes scratches and
striates the rocky ledges with which it comes in contact, but this action is
confined within narrow vertical limits, and the marks produced are by no
means so regular, or so deeply engraved, as those frequently made by
glaciers. The abrasion of river ice was observed by the writer under
favorable conditions along the Yukon river, but it did not appear as if the
smoothing and striation produced in that way, except, perhaps, when only
limited exposures were observable, could be easily mistaken for the work
of glaciers.

The action of floe ice on the shores of lakes and northern oceans, when
driven landward by wind pressure, on shelving beaches, makes the nearest
approach to glacial abrasion and striation that is known. Except that the
action of floe ice is confined to narrow vertical limits, it is difficult to
understand how the planing and striation it produces on the rocks bene ith
could, in the absence of other data, be distinguished from the work of
glaciers. Glaciers smooth and striate vertical walls, Jis well as flat sur-
faces, however, and make these and other records at all elevations from
the surface of the sea — and to a limited extent even below sea level —
up to the summits of lofty mountains. It is to be expected, also, that
the records of floe ice would be accompanied by other evidence, such as
deposits of clay and sand containing marine or lacustral shells, and topo-
graphic features due to the abrasion and deposition produced by waves
and currents. When a considerable body of evidenca is in hand in connec-

GLACIERS OF NORTH AMERICA.

m '

tion with the abrasion of ro( k surfaces in a given locality, there usually
remains no room for doubting in what way tlie planing and striation were
produced.

Special Features of Glaciated Surfaces. — The minor changes
produced on rock surfaces by the movement of ice over th^m are
so numerous that attention can only Ix- directed at this time to those
that are most common and most characteristic. The details of
these wonderful inscriptions can only be appreciated by studying the
originals.

Rock si;rfaces that have been subjected to the grinding of an ice sheet,
or crossed by even a small alpine glacier, are frequently found to be
worn and the angles and prominences rounded and planed away. All
weathered and oxidized portions of the preglacial surface are removed,
and the fresh hard ro k exhibits a polish approaching that given by
marble-workers to finished monuments. The hardest and finest-grained
rocks receive the most brilliant polish. Limestone, granite, and quartzite,
especially, are frequently so highly burnis)ied that they glitter in the
sunlight with dazzling brilliancy. On such surfaces there are usually
scratches and grooves, frequently in long, parallel lines, which show the
direction in which the ice moved over them. These markings vary in
size from delicate, hair-like lines, such as might be made by a crystal
point, to heavy grooves and gouges, a foot and sometimes several feet
deep, which frequently run in one general direction for many yards
and even several rods, and indicate by their straightness and evenness
that the engine which made them was one of great power and m-^ved
steadily in a continuous direction. In regions formerly occupied by
continental glaciers, particularly, two, and possibly three, well-defined
series of parallel striations are sometimes observable on the same sur-
face, crossing each other at varying angles. The most probable explana-
tion of these double or triple inscriptions is that the direction of the
ice current varied with the growth and decline of the glacier which
made them, or that the ice flowed in great swirls or eddies, as in the
case of the Malaspina glacier, and that the direction of these currents
changed with variations in the volume of the glacier, or perhaps with
variations in the amount of ddbris in the ice. On small areas the
parallel striations appear straight, but if one could examine square miles
of surface it would probably be found that the lines are frequently
portions of broad curves.

INTRODUCTION.

3re usually
iation were

)!• changes
thbin are

le to those
details of

iclying the

n ice sheet,
iind to be
away. All
e removed,
it given by
lest-grained
d quartzite,
tter in the
are usually
!h show the
ngs vary in
y a crystal
several feet
many yards
id evenness
and m^ved
ccupied by
well-defined
3 same sur-
)le explana-
ion of the
acier which
s, as in the
se currents
irhaps with
areas thr
quare miles
frequently

Occasionally the more strongly marked glacial grooves in resistant

i rocks, like hard limestone and quartzite, exhibit curved or semilunar

cracks, which cross the furrows from side to side at quite uniform

j intervals of a fraction of an inch up to au inch or more, and are con-

jvex in the direction of the former ice movement. These "chatter

marks" are thought to have been formed by pebbles that were checked

in their movement by friction, and when the force became sufficient to

carry them onward, were forced forward suddenly, perhaps turning over,

land struck the rock with such force as to produce cmcks. A similar

[action may be observed in sliding bodies, as wlien the wheels of a car

[slide on the track and a jar is felt when they slip and are arrested.

[These peculiar semilunar cracks are not confined to bottoms of grooves,

however, but appear on flat surfaces, where they are sometimes two or

three inches or more in length, and are separated by intervals fully as

great. These larger cracks, or " disrupted gouges," as Chamberlin has

called them, are concave toward the point of the compass from whicu

[the ice came.

Another characteristic feature of glaciated surfaces is observed when
[hard knobs occur in rock, as, for example, when limestone is charged
with small masses of chert, or with silicified shells and corals. In
[such instances the hard portions are left in relief by the abrasion of
the softer matrix. Starting from each elevation there are frequently
[raised ridges, tapering to a point in the direction of the ice movement,
land showing the manner in which the soft rock in the lee of the prom-
linences was protected. On the opposite side of such knobs, i.e. on
[the side from which the ice came, the rock is sometimes worn into a
[furrow, which bends around the obstruction, and from its form indi-
[cates that the ice behaved as a plastic body and moulded itself to the
Isurface over which it flowed.

Many other features of ice-worn surfaces might be enumerated,
nit in an elementary introduction it is perhaps better not to burden
Jthe reader with details.^

1 In the report on "The Rock Scorings of the Great Ice Invasion," byT. C. Chamber-
in, in the 7th Annual Report, U.S. Geological Survey, the reader will find many illustra-
lions of ice abrasion, accompanied by clear and concise explanations of the manner of
their formation, which will enable him to interpret such inscriptions for himself wherever
ifound.

GLACIERS OF NORTH AMERICA.

'Ill fi

Glacial Deposits.

The morainnl material carried by glaciers either on their surfaces
or within their mass, is left when they melt, and forms accumulations
to which, in part, the term moraine is still applied. The characteristics
of such abandoned moraines are frequently well exhibited in mountain
valleys from which glaciers have recently retreated. The most common
of these deposits are briefly described below.

Lateral Moraines. — The debris accumulated on the borders of an
ice stream, and constituting the lateral moraines of a living glacier, is
left when the ice melts and appears as a ridge or terrace at varying I
elevations. Steep-sided mountain valleys are frequently bordered on
either side by ridges of this character, which may be situated 1000 feet
or more above the bottom of the trough and clearly traceable for miles.
On the precipitous sides of such valleys, above the highest of the
abandoned moraines, the slopes are usually rough and irregular, and
bear evidence of the work of streams and rills descending from higher
elevations, as well as other results of atmospheric waste ; while below
the horizon referred to the relief is subdued, and the valley has the
smooth and flowing contours characteristic of ice work. Moraines of
this character are frequently similar to stream terraces, but usually |
have a raised outer margin, and besides are composed of angular and
unassorted material.

Terminal Moraines. — At various stages in the retreat of an ice
stream, the lateral moraines on its sides are united by a terminal
moraine, which crosses the abandoned bed of the glacier and forms a |
somewhat regular and usually crescent-shaped pile of stones, gravel, and |
sand, which is convex down stream and in many instances 100 feet or more
in thickness. Between successive terminal moraines the bottom of the
trough may be deeply filled with morainal material, deposited without
special arrangement, and in many instances evidently accumulated J
beneath the ice as a "ground moraine." These low spaces between
well-defined terminal moraines are frequently occupied by lakes or bv |
grassy meadows, and furnish some of the most charming features of
mountain scenery.

Morainal Embankments. — When a glacier is prolonged bey o] id ^
the entrance of a mountain valley and reaches an adjacent plain, it^P"^'*^'

INTUODUCTION.

may expand and end in a semicircular ice foot, or preserve its stream-
like form and finally melt without expanding laterally. The marked
contrast in the behavior of different glaciers in this respect depends on
the relative abundance of d<5bris in their lateral and in their ten:iinal
moraines. When the debris on the margins of a glacier is small in
volume, the ice has freedom to expand on getting Tree from the valley
through which it descended, but when the margins of the prolonged
stream are more heavily charged with debris than its extremity, lateral
exi)ansion is checked, while the clear ice at the extremity flows on.
The ice advances between the stagnant bordera of the stream to a greater
or less distance, depending upon the supply from the higher mountains ;
and when it retreats, the heavy lateral moraines are left as parallel
ridges with steep slopes on each side. These ridges frequently
resemble great railroad embankments. The best examples of structures
of this character that have been described are situated at the east base
of the Sierra Nevada, in Mono valley, California.^ Their general appear-
ance is shown in Plate 4.

Morainal embankments, like lateral moraines on the sides of a valley,
may be united by terminal moraines so as to form lake basins. When
the terminal moraines are composed of coai-se material and are too
open to retain water, or when they have been breached by overflowing
streams, grassy meadows and forest-covered parks, frequently of great
; beauty, occupy the spaces between them wliicli were formerly fiUeu by
[the retreating ice stream.

Frontal Moraines. — Moraines left by piedmont and continental

j glaciei"s are of the same general character as those deposited by alpine

glaciers, but are frequently of vast extent. The frontal moraines of

continental glaciers corresponding to the terminal moraines of local

ice streams, are in some instances a score or more of miles broad and

not only hundreds but thousands of miles long. Where two lol)es of

[a continental glacier come together *heir frontal moraines are united

[and form what is known as an interlohate moraine. The best known

lexaraples are in the upper Mississippi valley, and mark the junction of

Ithe larger marginal extensions, or lobes, of the Pleistocene ice sheet of

phat region.

1" Quaternary History of Mono Valley, California," 8th Annual Report, U. S. Geo-
logical Survey, pp. 300-368, Pis. 35, 30.

f _

"I^W

GLACIERS OP NORTH AMERICA.

Till. — Besides the irregular piles and ridges of unassorted d^bns
composing the moraines formed about the margins of glaciers, there
are accumulations of clay, filled at times with stones and boulders,
which are deposited l)eneath the ice during its advance, and fortn what
are frequently termed ground moraines. This material is widely spread
over formerly glaciated regions, and is now generally designated by the
Scottish name till, and is less frequently spoken of as boulder clay.
The term boulder clay, however, has been given a somewhat different
meaning by a few authors.

The characteristics of till aro its compactness, due to the pressure
to which it was subjected beneath the ice, and the worn and striated
condition of many of the pebbles and bouldera scattered irregularly
through it. As till was not exposed to the atmosphere during its de-
position, and, on account of its compactness, is impervious to surface
waters, the material of which it is composed is in an unweathered
condition and frequently of a bluish color, owing to the fact that the
iron contained in it has not been oxidized. Its unweathered condition
is in marked contrast to the surface moraines of many glaciers and to |
ancient glacial deposits which have been long exposed to the atmosphere.

Drumliiis. — The abandoned paths of great glaciers are sometimes
marked by smooth, oval hills that are lenticular in horizontal sections
and have their longer axes parallel to the movement of the ice which
formerly covered them. These peculiar and easily recognized emi-
nences are, in the case of certain typical examples, about 500 feet in I
least diameter, with a length of from 1500 to 2000 fee, and a maxi-
mum height of from 50 to 150 feet. They exhibit many variations in
tize and shape, however, some being nearly circular, mammillary hilh.
and othera lenticular hills, in which the longer axis is two or three
times as great as the shorter axis. In some instances they form narrow
ridges several miles in length. The beautiful curves formed by their
crests when seen from the side, is illustrated by the outline of a typi- ^
cal example near Groton, Mass., here presented. They occur at all
elevations from s;a level, and even below that horizon, to 1500 feet or |
more above tide, and are found on uneven, rocky ground as well as on
smooth plains. They are composed of compact till which is frequently
laminated, and seldom exhibit evidences of stratification or other wattr
action. Boulders and large angular stones occur within their mass, and
scattered over their surfaces. These peculiar hills, for which the Irisli

INTRODUCTION.

term drumlin is now gjiiemlly adopted, have been studied especially
near lioston, and occur also in many other parts of New England.
They are abundant in the upper portion of the Huflson Kiver valley,
in centiul New York, and have been reported from Michigan and Wis-
consin. In general they are situated well within the terminal moraine
which marks the southern limit of the last ice invasion of northeastern
North America. Many diundins in the Connecticut and Hudson val-

Pio. 2. — DRUHLnr nbab Groton, Mass. After Frvk.

leys, and other similar regions, are partially or wholly buried beneath
Champlain clays, which were deposited during a time of land depres-
sion immediately after the last recession of the ice. Thus far, drumlins
have not been observed in connection with existing glaciers. This is
due, perhaps, to the fact that they are not known to originate beneath
glaciers of the alpine type, and also because they seem to be a phase
of the l)t'havior of the somewhat central portions of large ice sheets, and
are only open to view when the ice has withdrawn.

The characteristic whahhack shape of drumlins, the compactness
and frequent lamination of the till composing them, as well as other
facts in connection with their composition and distribution, have led to
the generally adopted conclusion that they were formed beneath moving
ice sheets. Various hypotheses have been proposed to explain their
origin, but thus far opinion is divided in reference to the precise man-
ner of their formation. ^

Without attempting to present a review of the various hypotheses that
have been advanced in reference to the origin of drumlins, I venture to
suggest that the effect of debris on the flow of ice enclosing it may fur-
nish the desired explanation.

The presence of debris, i.e. boulders, stones, sand, dirt, etc., in glacial
ice, increases its resistance to motion, as will be more fully discussed in

^ A discussion of the origin of draralins, by Warren Upham, containing references to pre-
vious papers on the same subject, may be found in the Proceedings of the Boston Society of
Natural History, vol. 26, 1892, pp. 2-17.

V.6

OLACIKlta OF NORTH AMERICA.

;i I.

li !

;

advance. I)6hriH included in ic^e may Ih) said to .stiffen it and to decreiiHe
its pljiHticity ; or, in other wonls, increase its reHiHtiince to forces tendinpr
to shear it. With this principle in mind, we are led to conclude that if a
mass of d^hris is inchuhfd in a fjfhicier, motion in the debris-charged mass
will be retarded, ond the adjacent clear ice will flow around it. When the
debris reaches a >;!ertain proportion, varying with conditions, motion will
cease, and if the rate of flow of the clear ice does not increase, the ddbris-
charged niiuss will remain stagnant. If the debris is most abundant about
a central nucleus, and becomes less and less abundant in all directions
from the nucleus, the flow of the ice will be least in the center, or if the
debris is there suthciently abundant, will remain stagnant, while motion
in adjacent portions will increase in a definite ratio until the normal flow
of clear ice under given conditions is reached. If a nucleus of debris, as
above postulated, is situated in the central part of a glacier, with clear ice
beneath, it may behave like a boulder and be carried bodily forward ; but
if situated at the bottom it will retain its position, and the clear ice will
flow over it. If the ice flowing past the stagnant maas has earth and
stones scattered through it, the d6bris reaching the nucleus will Ije
retarded and the clear ice flow on. The nucleus of debris would thus
receive additions and be compacted and moulded by the clear ice, or ice
but moderately charged with foreign matter, flowing past it. A shape
presenting least resistance to llie flowing ice would thus be acquired,
and the longer axis of the stagnant mass would be parallel with the
direction of glacial flow. Under this conception of the growth of
drumlins, the fact that they frequently, and possibly normally, contain
debris that has been derived from lower levels presents no difficulty,
since ice under pressure behaves as a viscous fluid, and will flow in
the direction of I'^^st resistance. If the resistance at the sides of a
stagnant nucleus y^-kf greater than over its summit, the approaching ice
would rise and ii-w over the oKstruction, carrying with it the debris
contained wilhin its mass. The varying forms of drumlins, the fact that
they sometin.es cover a nucleus of rock-in-place, their laminated structure,
remarkable compactness, and general flowing outlines, all seem to harmo-
nize with the view of their origin here suggested.

Certain drumlins of what may be termed the New York type, i.e. those
that are greatly elongated, are not symmetric, but their ends in the direc-
tion from which the ice came which moulded them into shape are moder-
ately broader and more blunt than the opposite extremities. These elon-
gated hills may be said to have the shape of half a cigar cut lengthwise.

INTUODUCTION.

il».e larger end of the cigar pointing in the direction from which the ice
ciinie, which formerly covered the region where they occur. The sidcH
of these hills, an in common with all elliptical or elongated drumlins, are
more precipitous than the terminal .sloj)eH. On the larger or proximal
end8,of Heveral cigar-Mhaped drumlins observed by the writer in Wash-
ington county, New York, there is a noticeable increase in the nundn'r
of l)oulders scattered over the surface, while at their tapering or distal
extremities. Hue debris greatly piodominates, and is noticeable Ixjyond,
where the slope of the hills is lost. In these' examples, coarae debris
seems to haye Ixien deposited on the enlarged proximal ends, while
the sides and distal portion suffered erosion, which removed the larger
stones.

Under the hypothesis here proposed, drumlins are considered to have
grown by the accumulation of debris about a centnd nucleus either of
solid rock or of ice charged with stones to such a degree as to increase
its resistance above the shearing forces brought to bear upon it; the added
material being derived from the ice which flowed past it. The location
of a drumlin would be determined by the presence of debris sufficiently
abundant to cause stagnation in the ice containing it, which would vary
with the rate at Avhich the ice moved. When the ice contained but little
debris it might all l)e carried forward ; when the debris was in excess, it
might be left in a general sheet, without special form. The most favor-
able conditions would be when certain threads, so to speak, of the ice
current were lightly charged with debris, which on account of changes
in the contour of the land over which the ice flowed, or variations in
velocity due to other causes, would become sufficiently abundant at cer-
tain localities to check the flow of the debris-charged ice and cause it to
become stagnant. The ice current would then add fresh debris to the
stagnant nucleus, and a drumlin representing the excess of deposition
over erosion would result.

The hypothesis outlined above has not been subjected to severe tests,
and is introduced here in the hope that it v ill stimulate the student to
make observations in the field, which will either sustain it or lead to its
modification or rejection. In the study of the origin of topographic
forms, many trial hypotheses have to be introduced and their value
tested, in order to arrive at a true explanation. The above may be
considered an example of such a working hypothesis. It is the duty
of the compiler to take his reader as far as present knowledge seems
to warrant, and to point the way into the unexplored country beyond.

^ww

GLACIERS OP NORTH AMERICA.

I trust this little excursion beyond generally accepted conclusions will
encourage the student to continue the investigation.

il I

Glacial SEDiMENrs.

Deposits made by streams while yet confined by glacial ice, and for
some distance after escaping from its borders, may for convenience be
termed glacinl sediments^ in distinction from glacial deposits made
directly from the ice and classified as moraines, till, drumhns, etc.
These fluvio-glacial sediments are characterized by the worn and
rounded condition of the aand, pebbles, and boulders composing them,
and also by their moie or less perfect stratification ; while glacial
deposits are, in the majority of instances, composed of unassorted,
angular debris. Glacial sediments are in reality stream deposits made
under peculiar conditions, determined by the presence of land ice. For
this reason, they are of greatest interest when studied in connection with
other glacial phenomena. The deposits here referred to are designated in
many geological books, some of them of recent date, as modified drift ;
the early supposition on which this term is based being that they consist
of glacial deposits that have been worked over and modified by streams.
The leading characteristics of some of the bestrdefined deposits made by
glacial streams are briefly described below.

Osars. — In formerly glaciated regions there are, in certain instances,
long, gently curving, and sometimes tortuous ridges, trending with the
direction of former ice movement, and composed of water-worn sand
and gravel. When their internal structure is exposed, they exhibit
more or less well-<lefined cross-bedding or oblique stratification, pro-
duced by rapid water currents : and on their surfaces large, angular
boulders are frequently to L, observed. Ridges of this chai'acter, some-
times 50 to 150 feet or more in height, and perhaps scores of miles in
length, have been named osars, and are believed to have been formed
by streams flowing in channels beneath ice sheets. The large, angu-
lar stones resting on them are of the same origin as the similar bouldei's
on the surface of drumlins already referred to, and were deposited when
the ice in which the osars were formed was melted.

Karnes. — Other accumulations of water-worn sand and gravel, depos-
ited beneath glaciers or about their immediate margins, have irregular
shapes and form hills and knolls with undrained basins between. These

INTRODUCTION.

lusions will

peculiar and frequently very picturesque topographic forms are known as
kames. They are believed to owe their origin to the drainage of glacieir,
and to have been formed by the deposition of gravel and sand in cavities
beneath the ice, or after being swept out from ice sheets by the streams
flowing from them and dropped in open channels in their margins.
These are the most common of topographic forms composed of glacial sedi-
ments, and, like osars, frequently have large, angular blocks of rock scat-
tered over their surfaces, and are sometimes completely coated with what
was at one time englacial or superglacial material. They differ from osare
in the fact that they form inegular hills with basins between, instead of
long, winding ridges ; and are distinguished from drumlins, since they are
comi)Osed of water- worn sand and gravel, instead of till, and differ in
their outlines. Their distinguishing characteristics are, especially, t'.e
irregularity and frequent changes in the character of the layers of which
they are composed, their knob and basin topography, and the tact that in
general they trend at right angles to the direction of movement in the ice
sheet to which they owe their origin.

Sand and Gravel Plains. — About the margins of regions formerly
covered by ice sheets and associated with osars and kames, there are
frequently broad plains composed of irregularly strat! 'led sand and gravel.
These are the deposits made by overloaded glacial streams on emerging
from restricted channels in the ice and expanding and dividing into many
branches, and consequently dropping a large part of their loads, or flowing
inu; lakes where their sediments were deposited.

The formation of sand and gravel plains, both by subdividing streams
and in bodies of still water, may now be seen m progress about many
glaciers. Conspicuous examples occur at the extremities and along the
borders of several glaciers in Alaska. About Norris glacier in Taku inlet,
shown in Plate 11, there are large deposits of sand, forming a low,
gently sloping plain, across which the feeding stream divides into many
distributaries. Other deposits of this same general character will be
mentiou'id in advance in describing the Malaspina ice sheet.

Abundant examples of the deposits referred to above occur in the
region occupied by morainal material in the northeastern part of North
America, and also for many miles southward from the southenx limit
reached by the ice during what is generally termed the Second Glacial
epoch. Plains of sand and gravel, either formed in small lakes and having
horizontal f arfaces, or laid dov/n by bifurcating streams and having gently

GLACIERS OF NORTH AMERICA.

1 ::iili:!

sloping surfaces, make up a very large portion, and perhaps ihe major
part, of glacial deposits over great areas in the region of the Laurentian
lakes. At times these plains are marked by depressions, frequently rudely
circular in outline, with steep banks of gravel and sand, and in such in-
stances have acquired the name of pitted plains. The pits dotting their
surfaces, and forming a marked chamcteristic of their topography, are
believed to have been formed by the melting of isolated ice bodies which
were surrounded or perhaps deeply buried by the gravel and sand during
the last retreat of the glaciera.

Changes in Topography Produced by Glaciers.

Glaciers have a twofold and opposite effect upon the relief of the
regions they occupy. The abrasion produced by moving ice masses tends
to reduce and smooth out inequalities, cut away prominences, and, as a
minor feature, excavate rock basins. The deposits foi (Tied nrlaciers, either
directly or through the agency of streams, in many Oi.aCo ^iii up and level
off previously formed depressions, but in other instances, especially during
retreat, tend to accent the relief of the surface and produce inequalities.
The debris carried by ice streams and by ice sheets is left in confused
heaps when melting takes place, and produces well characterized topo-
graphic forms. Frequently these deposits cover immense regions, and
are striking in appearance, and vary abruptly in relief. The sediments of
glaciers, and particu] \rly the fine debris washed from them by outflowing
water, fill inequalities, and on the whole, except in the case of osars and
similar accumulations, tend to subdue and make uniform previous
inequalities of the land.

About the margins of existing glaciers that are retreating, ■ > are
barren areas in which the topographic forms peculiar to glacia! i,* re

well displayed. In such instances one finds tumultuous piles of eay; " lud
stones, now rising into knolls and steep-sided hills, and, again, sinking into
dales and sand plains with but little variation in the surface contours.
One of the most striking features in these fresh morainal deposits is the
presence of many depressions without surface outlets and very frequently
containing lakes. The drainage is markedly immature.

On old moraine-covered areas the ruggedness is commonly concealed
somewhat by vegetation, and many of the lakes that formerly existed in
the depressions are transformed into bogs and grassy meadowt. Streams
originating in such areas cut channels for themselves and tend still

INTRODUCTION.

further to drain the land. As time goes on, a well-developed drainage
system is established. The lakes disappear, and the work of the streams
in reducing the country to base level, i.e. the level of standing water into
which they discharge, is carried forward much the same as in regions that
have not been affected by glacial action. This task is frequently greatly
delayed, on account of the climatic conditions and for the reason, also,
that glacial deposits, especially osars, kames, etc., composed of unconsoli-
dated gravel and sand, are^ufficiently porous to absorb the rain water that
falls upon them and allow it to percolate slowly f^way, thus robbing it of
its power to erode. The most prominent relief of glaciated lands is fre-
quently such 18 is produced by open, porous deposits of the nature of
kames and osars. These retain their primitive form, while mountains of
indurated rock yield to the forces of the atmosphere and are sculptured
in various ways.

The most pronounced topographic evidences of the former presence of
an ice sheet are irregular moraines ; undrained basins ; numerous lakes ,
long, winding gravel ridges, or osars ; tumultous hills of gravel, or kames ;
lenticular hills of till with smooth surfaces, or drumlins ; broad and
frequently gently sloping gravel plains, sometimes with pitted surfaces ;
boulders, occasionally perched on hilltops and mountain sides ; faceted
and striated stones ; outcrops with smooth and rounded contoui-s, and
polished and striated surfaces.

With ihis elementary discussion of the general characteristics of
glaciers and of the records they leave when climatic changes lead to their
disappearance, we will pass in the following chapters to an account of the
glaciers now in existence in North Ambrica.

;

CHAPTER II.

GENERAL DISTRIBUTION OP THE GLACIERS OF

NORTH AMERICA.

The glaciers of North America are confined to the Cordilleran
mountain series and to the Greenland region.

Cordilleran Reg-ion. — The Cordilleran series is, in fact, a family of
mountain systems in most of which there are several independent ranges
and multitudes of individual peaks. It is the longest mountain series in
the world, extending as it does from Cape Horn to the western extremity
of the Aleutian islands, a distance of over 7000 miles. In Central
America it is represented by a single system, in Mexico it becomes divided,
and in the United States it is definitely separated into the Rocky mountains.
Sierra Nevada-Cascade, and Coast systems. In Canada the breadth of the
series increases northward, and four well-defined mountain systems are
recognized, viz. : the Rocky, Gold, Coast, and Vancouver. What is known
as the Coast range in Canada is not a continuation of the Cascade mount-
ains, as sometimes stated, but is distinct from them both topographically
and geologically. Vancouver system may sound strange to many readers,
but is an appropriate designation, proposed by the Geological Survey of
Canada, for the great system of uplifts beginning at the south in the
Olympic mountains, Washington, and extending northward through
Vancouver and Queen Charlo^^te islands, and attaining its greatest
development on the coast in southern Alaska, and finally terminating
at the west in the Aleutian islands.^

In Canada and Alaska the mountains of the Cordilleran series near
the coast become more elevated than those of the interior and bend
abruptly westward in the central part of their course. The eastern
system in the same series is prolonged northward, and judging from the
meagre information at hand, decreases in height and ends indefinitely
before reaching the shores of the Arctic ocean.

1 A. R. C. Selwyn and G. M. Dawson, " Descriptive Sketch, Geological and Geographic,
of the Dominion of Canada," Montreal, 1884, p. 35.

DISTRIBUTION OF THE GLACIERS OF NORTH AMERICA.

Several of the great volcanic peaks of Mexico, which belong with the
Cordilleran series but are of secondary origin, attain an elevation of from
17,000 to over 18,000 feet, a.*vl leach the horizon of perpetual snow. In
some instances true glaciers of small size are ::aid to exist about their
summits, but little if dny reliable information is available concerning
them, however, and we are obliged to pass them by.

The southern limit of glaciers in the United States is in the High
Sieri-a, California, in about latitude 39°. The ice bodies of that region
are small, but have many of tlie essential features of the most typical
ice streams of the alpine type. They are confined to sheltered amphi-
theatres about the highest peaks, and do not extend l'>wer than about
13,000 or 12,000 feet above the sea. In most instances they are at
the northern base of sheltering precipices, and terminate before reaching
the upper limit of timber growth.

In northern California, and in Oregon and Washington, glaciers are
more numerous, of greater extent, and reach lower limits than in the
Sierra Nevada, but are still confined to the higher portions of the more
elevated peaks and do not extend to a lower horizon than about 6000
feet above the sea. In many instances they reach the upper limit of forest
growth. The best examples cluster about the summits of Mount Shasta,
Mount Rainier (Tacoma), Mount Baker, and other volcanic peaks of the
same region.

In the Rocky mountains, glaciers are foreshadowed at the south by
small snow bodies in Colorado, which certain travelers who have examined
them consider worthy of being numlgred among glaciers.^ Perennial
snow banks increase in number and in extent towards the north, and true
glaciers occur in Montana and adjacent portions of Canada.

Glaciers are numerous in the Cordilleran series in Canada and furnish
some of the most attractive features in the scenery of that Wild and
picturesque land, but unfortunately only meagre information concerning
them is yet available. The best known examples appear in the Selkirk
mountains, one of the loftiest ranges in the Gold system, and in the
Coast mountains in the vicinity of the Stikine river. Further north, in
the same great mountain series, bodies of perennial ice become more and
more numerous, at the same time increasing in size, and reach their

Geographic.

1 F. H. Chapin, "The First Ascent of a Glacier in Colorado," Appalachia, vol. 6, 1887,
pp. 1-12.

An account of the occurrence of typical glaciers near McDonald lake, in northern
Montana, by L. W. Chaney, Jr., was published in Science, vol. 2, 1896, pp. 792-706.

GLACIERS OF NOlilH AMEUICA.

I'^iii m

most magnificent development in southern Alaska. The most thoroughly
ice-covered region in the Cordiileran series is in tne vicinity of Mounts
Fairweather, Logan, and St. Elias, and lies partially in Alaska and
partially in Canada. Westward from that stronghold of perennial
ice, as previously stated, the mountains decrease in elevation. The
effec". of this change, and probably also of accompanying variations
in climatic conditions, is seen in the glaciers, which become smaller and
more widely separated and are confined to higher and higher regions
when traced westward t > the Alaska peninsula and the Aleutian islands.

As one follows the great Cordiileran glacial belt northward from its
first appearance in the High Sierra, the lower limit of perennial snow, or the
"snow line," at first about 12,000 feet above the sea, descends lower and
lower, until finally in the vicinity of Mount St. Elias it has an elevation
of only 2000 or 2500 feet. Farther west, along the curve made by the
mountains about the northern shore of the Pacific, the snow line again
rises, and on the Aleutian islands has an elevation of perhaps 8000 or
10,000 feet. The glacial ice everywhere extends below the limit of peren-
nial, n6v6 snow, but is most thoroughly exposed in late summer or early
autumn, when the true position of the snow line is sharply defined. In
the High Sierra, the extension of glacial ice below the neves is but slight,
and during seasons of unusual snowfall, or when the summei-s are excep-
tionally cool, may not be recognizable. Proceeding northward, the ice
extension is more and more pronounced, until the region of maximum
glaciation is reached. Thence westward the length of the tongues of ice
below the snow fields decreases.

In the High Sierra, as already stated, the glaciers do not descend
below about 12,000 feet ; farther north they reach lower and lower limits,
until in the vicinity of Stikine river, in about latitude 67°, they gain the
sea level. Thence northward and westward to beyond Mount St. Elias, a
distance along the coast of between 700 and 800 miles, there are
hundreds and probably thousands of glaciers that descend practically to
sea level, and scores that enter the sea and, breaking off, form bergs.
Beyond the Mount St. Elias region their lower limit gradually rises.

At the southern end of the crescent-shaped belt of glaciere under
consideration, the ice bodies are small and detached, and are sepai'ated
from each other by intervening ridges and mountain peaks. Proceeding
northward, they increase in area and in frequency, and unite one with
another in the neve region. The snow belt broadens and finally becomes
a confluent sheet 80 or 100 miles broad in southern Alaska, and narrows

DISTKIBUTION OF THE GLACIEUS OF NORTH AMERICA.

again westward and is there broken into individual n^v^s of limited
extent similar to those of the High Sierra. The most thoroughly snow
and ice-cove»ed portion is in the region between Lynn canal and Cook's
inlet, Alaska, where not less than 15,000 square miles of mountainous
country is almost completely buried beneath a single vast nev6 field from
which ice streams of the alpine type flow both north and south through
rugged defiles in the flanks of the mountains. The southward flowing
glaciers are larger, more numerous, and much longer than those that find
their way northward, and, in gaining the low lands adjacent to the ocean,
expand and unite one with another, so as to form broad plateaus of ice,
known as piedmont glaciers.

Could the observer obtain a bird's-eye view of the western portion of
North America, he would find that the Cordillera' glaciers form an irreg-
ular curve, broadest and reaching sea level in the Mount St. Elias region,
and narrowing and becoming more and more elevated at lx)th its southern
and western extremities. The attenuated arms of this shining crescent are
broken, for the reason that only the more elevated mountains near its
extremities -jach the horizon at which perennial snow exists. As in the
crescent of light reflected from the surface of the moon, the mountains in
the Cordilleran ice crescent where the belt is broadest are white to their
bases, while only the peaks of the most lofty elevations at the extremities
of the broken circle are brilliant. The length of this crescent of snow
and ice is about 3000 miles. Its form is less regular, however, than the
comparison made above might lead one to suppose, as its southern
prolongation is broader and more broken than its central a^nd western
portions.

The study of the glaciers of the Cordilleras has only fairly begun, but
it is hoped that what has already been accomplished will convince the
reader that the subject is not only worthy of consideration, but of fascina-
ting interest, and that the work of exploration should be continued.

Greenland Region. — In the eastern portion of North America gla-
ciere are confined to Greenland, and to the islands adjacent to it on the
west. The vast ice sheet covering nearly all of Greenland is of the contin-
ental type, and, as is well known, is the largest existing ice body in the
northern hemisphere. Its extension northward has not been fully deter-
mined, but as nearly as can be judged it terminates in about latitude
82 °. Its a,vei is in the neigLoorhood of 600,000 square miles. If
transferred bodily to the eastern portion of the United States, it would

GLACIERS OF NORTH AMERICA.

extend from northern Maine to Georgia, and cover a belt of country 500
miles broad. Vast as this ice 8he,.t is known to be, it takes whit- may be
said to be second or third rank when contrasted with the continental
glaciers that occupied Canada and a large portion of the United States in
Pleistocene times. The exploration of existing glaciers derives one of its
principal attractions from the fact that such studies assist in interpreting
the records left by ancient glaciers in various parts of the world. This
in turn brings one to the consideration of the still broader problems of the
cause of climatic changes which favored the growth of vast Pleistocene
glaciers in regions now enjoying a temperate climate, and inhabited by
the most civilized people of the earth.

The glaciers on the islands to the west of Greenland are but imper-
fectly known, but from the somewhat meagre reports rendered by Arctic
explorers, few of whom, it is to be regretted, have been trained observere in
this direction, it appears that they are of the alpine type, although larger,
and with broader neve fields in proportion to the extent of true glacial
ics, than is found among the s^laciei's of Switzerland or other similar
regions. A remarkable feature of the glaciers of the far north is that
they frequently terminate in bold precipices of ice.

Having this general sketch of the distribution of glaciers in North
America in mind, the reader will be enabled to locate in the outline plan
the relations of the various ice bodies described in the following chapters.

CHAPTER III.

GLACIERS OP THE SIERRA NEVADA. '

The Sierra Nevada, in many respects the most attractive mountain
system in North America, attains its greatest elevation between hititude
30° and 38° 30', or in a more general way, between Owen's lake and Lake
Tahoe, California.

The High Sierra.

To the more elevated portion of the Sierra Nevada the name " High
Sierra " has been applied. Although the boundaries of the region thus
designated are indefinite, it is well worthy of especial recognition, as it is
a prominent and important topographic feature. Throughout its entire
extent it bristles with rugged peaks, narrow crests, and inaccessible cliffs,
overshadowing profound chasms, all of which combine to form one of the
most rugged and picturesque mountain ranges in North America. The
culminating point of this elevated region is near its southern limit, where
Mount Whitney rises to an elevation of 14,522 feet above the sea, and is
succeeded northward by Mount King, Mount Humphreys, and man}' other
elevations scarcely less magnificent. Southward from Mount Whitney the
Sierra declines rapidly, and the system is considered as terminating in that
direction at Tehichipi pass, a little north of latitude 35°. Northward of
Mount Whitney, there is a vast sea of rugged peaks and narrow moun-
tain crests, separated by deep valleys, which render the region almost inac-
cessible to beings not eqinpped with wings. This is the High Sierra
par excellence^ as will be admitted by all who attempt to scale its giddy
heights or thread its labyrinth of cations. In the neighborhood of Mono
lake a number of the more prominent peaks, of which Mount Lyell,
Mount Hitter, Mount Dana, and Tower peaks are examples, exceed 13,000
feet in elevation. The range retains its rugged character all the way to
Sonora pass, and even to Lake Tahoe, but northward of that " Gem of
the Sierra " the mountains are less elevated.

1 This account of the glaciers of the Sierra Nevada is taken almost entirely from a paper
I by the present writer, on the " Existing Glaciers of the United States," 6th Annual Report
U. S. Geological Survey, 1883-84.

GLACIERS OF NOIITH AMKUICA.

vli;

Very liirpo portions of tlie Higli Sierni iire c-omijosed of lightrcolored
granite, but thinly flotlu'd with vegetation, whieh inii)art8 a monotonous
gray tone to the rugged scenery. The peaks and crests overlo(»king Moiu*
lake, however, liave been sculptured from metamorphosed sedimentary
rocks, and are frequently richly tinted. The landscape in this portion
of the range is warm in tone, and presents pleasing and striking contrasts
ill comparison with the gray of the western slopes. Hugged and angular
precipices rising to narrow crests, hut softened in contour and varied in
color on their lower slopes by lichens and al[)ine llowers, dark billowy
forests of pine in the valleys, snow-lillcd am[)hitheatres, and hundreds of
placid lakelets and rock-rinuncd tarns are there grouped in i)i(,'tures that
are as delicate in detail and as pleasing in tone iw they are majestic and
far-reaching. ' '

Besides the splendor of their scenery, the mountains to the south-
ward of Mono lake present the additional attraction of living glaciers.
These, although small, are well worthy the careful attention of every
traveler.

Existing glaciers on Mount Dana and Mount Lyell were visited by
Mr. (t. K. Gilbert and myself during the sununer of 1883. I also exam-
ined one at the head of Parker creek, a tributary of Mono lake. Others
on Mounts Conness, McClure, and Ritter were explored by Mr. W. D.
Johnson, my associate for several years in western explorations, while
making a topographical survey of the region draining to Mono lake.
Besides the glaciers actually traversed, a number of others were seen
from commanding points, and their general nature almost as thoroughly
determined as if their surfaces had actually been trodden. Our combined
observations show that nine glaciers exist within the southern rim of the
Mono lake drainage basin. A somewhat larger number are sheltered by
the mountains, of which the dominant peaks are McClure, Lyell, and
Hitter. It is in ice caves beneath these glaciers that the Tuolumne,
Merced, and San Joaquin rivers have their birth.

The glaciers of the High Sierra are located between latitudes 36" 30'
and 38°, ana at their lower extremities have an approximate elevation of
11,500 feet above the sea. The lowest seen is on the northern side of
Mount Ritter, and terminates in a lakelet that is about 2000 feet below
the mountain top, or about 11,000 feet above the sea. The glaciers
observed are all small, the most extensive — that on the northern slope
of Mount Lyell — being less than a mile in length, with a somewhat
gi'eater breadth. Nearly all occur in amphitheatres on the northern side

);i,AitKHi« ">K N'liHIII AMKIch.4.

I'r. kTK '.'.

Fig. a. — mount DANA GLACIER, CALIFORNIA.
( >ii tli<' iiortlicrn «iiU' "f the smiiiiiit-|n'iik of .Ml. I >iiiiii.

Fig. B.— mount LYELL GlACIER, CALIFORNIA.
The liiKhest peak is the sutnmit of Mt. Lyell.

GLACIERS OF THK SIERRA NEVADA.

(if lofty peaks, where they are fiheltored from the iiooiulay sun hy liigh
cliffs and mountain ridges; and all How northward, with the exception of
a few cradled in deep cirques on the eastern side of the Minarets and
Mount Hitter. So far iis known, these are the most southern glaciers in
the United States. Snow fields are reported hy Mr. Johnson, however,
as existing in the mountains to the south of Mount Hitter, at the head of
some of the many brandies of Owen's river. If these should pn)ve to 1k3
veritable glaciers, they will extend the southern limits of the existing
glaciera of this country a few miles farther southward.

Mount Dana Glacier.

On the western shore of Mono lake the mountains rise abruptly from
the water's edge to an elevation of 5000 to 6600 feet, and have Iweii
sculptured by storms and frosts into indei)endent peaks of remarkable
giandeur. As seen from Mono lake, the most conspicuous point along
the serrate mountain crest outlined against the western sky is Mount Dana,
which rises 6600 feet abov«^ the lake, and has an elevation of 12,992 feet
above the sea. Although grand proportions, this peak is but one among
many prominent points crowning the divide between the drainage of Mono
lake and the Pacific. From the southward, Mount Dana presents a
somewhat rounded contour and is easy of ascent, but on the north its
culminating cliffs form a nearly perpendicular precipice more than a
thousand feet high. This northern face descends into a deep, narrow
gorge leading northward, known as Glacier cafion. During the glacial
epoch the whole extent of this cafion was occupied by ice, and formed a
tributary to a still larger glacier flowing into Mono valley.

At the head of Glacier cafion, and surrounded on nearly all sides by
towering precipices, lies the small ice body represented on Fig. A, Plate
2, to which the name Mount Dana glacier has been given. The picture
shows nearly the entire extent of the glacier, and is from a photograph
taken on an abandoned terminal moraine now retaining a lake of opalescent
water, into which the drainage from the ice discharges. In the illustra-
tion the terminal moraine now forming about the border of the ice can be
seen, as well as the crevasses, dirt bands, etc., that mark its surface. The
glacier is about 2000 feet long in the direction of flow, but appears much
foreshortened in the illustration. " Ice tongues " are seen extending uj>-
ward from the neve. At the base of the largest of these peculiar ice
tributaries a portion of a wide crevasse, or bergschrund, may be recognized.

GLACIERS OF NORTH AMERICA.

Ill

This miniature glacier exhibits many of the essential features of greater
ice streams, such as neve and glacier proper, crevasses, dirt bands,
morpines, glacier tables, etc., as will be described in connection with simi-
lar features on neighboring ice bodies a few pages in advance.

Mount Lyell Glacier.

In traveling ^rom Mount Dana to Mount Lyell, one finds it most
convenient to pass down Dana creek, which flows southward from
Mount Dana, to its confluence with Tuolumne river, and then ascend
the deep, broad caflon of the latter stream. Tuolumne river has its
birth at the extremity of the Mount Lyell glacier. It emerges from u
cavern in the ice as an insignificant, dirt-laden brook. The snowy
summit of Mount Lvell, as seen from the head of Tuolumne cafion, is
shown in Plate 3. The majestic mountain, when viewed from this
portion of the vp.Uey, is far more beautiful than any illustration in
black and while can suggest. In the soft, gray light of morning, it
has all tile solemn grandeur of the Tiernese Oberland. At sunset,
when flushed with the rosy light of the afterglow, this shrine of the
High Sierra rivals the splendor of Mount Rosa, To the right of Mount
Lyell rises Mount McClure, which is scarcely less imposing than its
companion; the former attains the height of 13,420 feet above the sea,
and the latter is but 150 feet less in elevation.

The Tuolumne cailon, when followed still nearer its beginning, is found
to lose its gentle grade and become rugged and precipitous. Its bed is
crossed at jntervalt^ by irregular cliffs, that must have caused magnifi-
cent ice cascades in the great glacier that once flowed over them. Tho
top of each steep ascent is usually separated from the base of the next
higher one by a comparatively level tract, sometimes holding a grassy
meadow or small, rock-enclosed tarn. This succession of cliffs and
terraces forms a grand stairway, leading to the opening of the amphi-
theatre on the north side of Mount Lyell, where a magn'ficent pano-
rama of the entire glacier may be obtained. The view given on Fig.
E, Plate 2, is from near the outlet of the amphitheatre, and exhibits
nearly the whole extent of the n6ve of the Mount Lyell glacier and
ol the small area of compact ice which projects from beneatli it In
the panorama the terminal moraine of dirt and stones, now forming'
at the foot of the glacier, may be recognized, and also the rounded
and worn rock masses that rise as islands in the central portion of the

GLACIERS OF THE SIERRA NEVADA.

sjlacier. Crevasses, contorted dirt bands, and moraines on the ice,
although noticeable features when traversing its surface, are but indif-
ferently shown m the illustmtion.

Parker Creek Glacier.

This glacier is situated at the head of a deep, high-grade caflon, down
which Parker creek descentls on its way to Mono lake. It is even smaller
than the ice bodies on Mount Dana and Mount Lyell, but is yet a true
glacier with a well-defined n^v6 region, from beneath which descends
a mass of ice that is crossed by dirt bands and crevasses, and has many
minor features that duplicate the details of more extensive ice streams.
About the lower margin of the ice there are comparatively large moraines
forming concentric ridges, and indicating the rapid disintegration of the
surrounding cliffs, since the material of which they are composed was
derived entirely from that source. The mass of debris surrounding
this glacier appears to exceed the volume of the ice of which it is
formed. These moraines are more characteristic examples of tho
tumultuous debris piles formed by ice streUms than any other deposits
of the same nature now forming in the High Sierra. Like the majority
of the glaciers of this region, the one at the head of Parker creek is shel-
tered by overshadowing walls, and flows northward. During the glacial
epoch, the entire extent of the deep valley through which it flows was
occupied by a glacier that descended upon Mono plain, and built huge
morainal embankments more than a mile in length. These fine examples
of the peculiar parallel embankments built by overloaded glaciera on
emerging from mountain gorges are second in interest, however, to
similar deposits at the mouth of the neighboring gorge, known as
Bloody caflon,! ^nd illustrated on Plate 4.

Characteristics of the Glaciers of the High Sierra.

That the ice bodies observed in the High Sierra, although small, are yet
veritable glaciers, I trust will appear from the following somewhat detailed
statement of observations :

1 The instructive records left by Pleistocene glaciers in the nei{,'hborhood of Mono lake
are described and illustrated in "Quaternary History of Mono Valley," in the 8th Annual
Report of the U. S. Geological Survey, 1886-87, pp. 261-394.

^pp*

GLACIERS OF NORTH AMERICA.

N^vds. — The distinction between n6v6 and true glacial ice is plainly
manifest on nearly all of the glaciers of the High Sierra. This is apparent
not only when viewing them from a distance, but also while traversing
their surfaces. In the case of the Parker Creek glacier, especially, the
change from the granular snow of the neve to the compact ice of tlie glacier
proper, can be discerned within the space of a very few feet. The neves,
although usually dust-covered, are invariably white as compared with the
rest of the glacier, and are composed of granular ice-snow. Their surfaces
are almost entirely free from stones and dirt, and are rendered very rough
and uneven by crests and spires of compact snow or neve ice, from two to
five feet high, that result fvom the unequal melting of the surface. These
" ice blades " have been described by Professor Le Conte, who refers their
origin to the unequal melting of wind-rippled snow.

At their lower limits the n^v^s pass into the glaciers proper, which in
part they overlie, and acquire a ribboned or laminated structure, dirt
bands, etc., characteristic of true glaciers.

Crevasses. — Marginal crevasses were observed in numerous instances,
but they occurred in quite limited numbei-s in any individual glacier. In
some examples, more especially in the neves, they are convex toward the
head of the glacier, while others far down in the same series are straight,
or hrtve changed their c irvature so as to be concave up stream. The cre-
vasses are largest at the upper margin of the neves, and frequently corre-
spond to the bergschrund of Swiss mountaineers. They vary from narrow
cracks up to chasms six or eight feet wide, and frequently cross almost
the entire breadth of the neve, thus rendering difficult the passage to
the rocks above. The depth of the crevasses could seldom be deter-
mined, as the irregularities of their sides limited the view, but some were
certainly not less than 100 feet deep. The crevasses were frei{uently
partially concealed* by arches of snow, hung within with vast numbers of
icicles. The walls beneath these treacherous roofs are incrusted with large
masses of well-formed ice crystals, with glittering faces half an inch in
diameter, resembling the most beautiful transparent spar. The light in
the^e fairy-like grottoes is of the most exquisite blue.

Lamination, or «« Ribboned Structure." — This structure was seen
in all the glaciera closely examined, but appeared most conspicuously
near the lower extremity of the ice, where the layers are approximately
horizontal. Hand specimens cut from the ice exhibited sections of alter-

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GLACIERS OF THE SIEKKA NEVADA.

nating narrow bands of compact blue ice and porous white ice, as plainly
as could be desired.

Dirt Bands. — These were observed on nearly all of the glaciere, and
were frequently jnarked, and even conspicuous, features of their surfaces.
It required no peculiar condition of light and shade to make them discern-
ihle ; on the contrary, they could be plainly distinguished at a distance of
two or three miles. Viewed from a distance, they were seen to sweep
entirely across the glacier in a series of graceful curves, concave toward
the neve. Sometimes this symmetry was interrupted by irregular undu-
lations, or even by contortions, as may be seen in the illustnition of the
Mount Lyell glacier. On Parker Creek glacier the dirt bands are about
six inches broad over a considerable area, and occur at quite regular inter-
vals of four to six feet, with comparativiely clear ice between. In this
instance, the dirt producing the bands was not confined to the surface,
but could be seen to discolor the ice in well-defined strata, dipping into
the glacier at a low angle with the surface. On all of the glaciei-s
examined, the dirt bands were observed only below the lower limit of
the neve.

In the study of the glaciers of Switzerland and Norway, particular
attention has been given to the influence of ice cascades in producing
lamination and dirt bands. In the Sierra Nevada glaciei-s, both of these
characteristics are distinct and well marked, but ice cascades are absent.
It seems evident, therefore, that the hypothesis which is apparently satis-
factory in Europe does not agree so well with the phenomena observed in
California.

In viewing many of the Sierra Nevada glaciera at a distance of a few
miles, and approximately on the same level, it is appar'^nt that their
surfaces frequently have a slope of from 15 to more than 30 degrees, and
are, in fact, sections of the ice bodies in which the internal structure is
exposed. When seen in this manner the appearance of the glaciers is
such as to lead one to suspect that the dirt bands are strata in the ice,
or in reality "annual rings"' formed by yearly accumulations of dirt
on the n^ves. A similar explanation was long since advanced by
Forbes after studying the dirt bands of apparently the same character on
Swiss glaciers. Prof. H. W. Brewer has suggested a modification in
this explanation to the effect that a year of exceptional melting — one
of those years in which the n6v6 is reduced to the minimum — would
have the effect of combining the dirt accumulated during several years

GLACIERS OF NORTH AMERICA.

into a single band, which would represent a climatic cycle rather than
a single year. This explanation agrees best with the facts noted above.

Glacier Tables. — Blocks of stone perched on columns of ice, and
usually designated glacier tables, did not form a marked feature on the
ice bodies of the Sierra Nevada in 1883, except in one instance. On
Parker Creek glacier they were numerous and in all stages of growth
and decadence. Some of the blocks of stone were poised horizontally
on pedestals of ice ; others were inclined southward, or had been partially
dislodged, and in some instances they had fallen and were lying on the
southern side of pinnacles which had formerly supported them. Sketches
of some of the more characteristic examples observed, diawn to a scale
of about one foot to the inch, are here shown.

Fig. 3. — Glacier Tableb, Parkeb Ckeek Glacier, California.

The largest glacier table was observed near the cente/ of the Parker
Creek glacier, a few hundred feet fro*^.^ its terminus. This is a block of dense
volcanic rock measuring 24 X 33 X 10 feet, and was supported by a column
of ice eight feet high on its northern and six feet high on its southern side,
and six to eight feet thick. The smallest observed blocks that are able to
protect the ice beneath sufficiently to form columns as the general surface
melts away were found to be about 16x10x10 inches ; when smaller
"than this they sink into the surface in a manner that is well known to all
alpinists. Small pebbles are frequently seen at the bottom of little ice
wells five or six inches deep, but good examples of sand cones and some of
the other minor details of glacier surfaces were not observed.

GLACIERS OF THE SIERRA NEVADA.

Ice Pyramids. — As the forms included under this name f urnisli a
detail of glacier surfaces not described before the glaciers of the High
Sierra were examined, I shall transcribe my notes concerning them at
some length.

On the lower portion of the Mount Lyell glacier, more especially than
in any other observed instance, the surface .bristles, over large areas in the
neve region, with acute pyramids of snow-ice from a few inches to fully
tliree feet in height, with bases having a diameter of perhaps one-half
tlieir height.

At the base of each pyramid on its northern side, there is invariably a
stone, sometimes measuring five or six inches in diameter, or a number of
loose pebbles, or a handful of dirt, which is usually depressed somewhat
below the general surface of the neve. The side of the pyramid rising

Fio. 4. — Ice Pyramids, Mount Lyell Glacier, California.

above the stone, i.e. the northern face, is usually concave, in horizontal
sections, and invariably composed of clear, compact ice, while the remainder
of the structure is of the ordinary porous ice forming the glacier surface.
Sometimes the nearly horizonttil lamination of the glacier ice can be seen
in the pyramids. A direct relation is noticeable, too, between the size and
shape of the stones and the height and form of the ice pyramids rising
above them.

In seeking an explanation of these phenomena, the only hypothesis that
seems to satisfy the observed facts, assumes that a stone or jnass of dirt
lying on the surface of a glacier becomes heated and melts the porous ice
beneath, and that the water thus formed freezes again into compact ice,
which resists the sun's heat more thoroughly than the surrounding porous

GLACIEUa OF NOltTH AMEKICA.

ice, and hence is left as the general surface melts away. In nearly every
instance, the stone at the base of the pyramid had been carried northward
as it melted its way downward, thus forming the steei), northern slope of
the pyramid, and at the same time tending to prevent the formation of a
prominence on the northern side of the sunken block. The pyramids
alwa^'s point toward the noonday sun, hence the compact ice formed on
tiie nortliern side of a pebble is more exposed than the ice on its southern
side, and is« therefore, more rapitlly melted.

Moraines. — No well-marked medial moraines were noticed on any of
the Sierra Nevada glaciers. The reason for their absence is because the
glaciei-s are simple ice streams, without tributaries. Lateral moraines
resting on and inclosed in the ice at the margins of the glaciers were seen
in many instances, and could be traced without difficulty to the cliffs fvom
which they came. Terminal moraines, however, are common, and occur
at the lower limit of every glacier observed, and owe their existence to
the moderate amount of morainal material scattered over the surfaces
or contained in the glaciers, without being concentrated into medial
moraines. The terminals are remarkable for their size, when compared
with the extent of the parent ice streams, indicating that the process now
observed has been going on essentially as at present for a long term of
years. The terminal moraine now forming at the lower extremity of
Mount Dana glacier is approximately 1000 feet long by 30 or 40 feet
broad, and api)arently 100 feet or more deep. Below this, and partially
united with it, is a second ridge of debris of somewhat greater dirien-
sions, which is followed by other similar crescent-shaped piles lower
down the gorge. The corresponding moraines at the extremity of
Mount Lyell glacier are considerably larger, as are also the still more
typical terminals at the foot of the Parker Creek glacier. In some
instances these moraines were coated with loose rubbish and dirt that
would be swept away by a single storm, indicating that they had received
their last addition within a very few months.

The bottom of the Dana glacier was seen to be heavily charged with
stones, pebbles, and sand, and to rest on a bed of boulders of a consider-
able thickness. This subglacial deposit may with propriety be termed a
ground mor9,ine.

Glaciated Surfaces and Scratched Stones. — The rock surfaces in
the immediate neighborhood of the Sierra Nevada glaciers are frequently

OLACIEHS OF THK SIEKHA NEVADA.

polished and covered with grooves and scratches, bnt it is usually impos-
sible to determine whether this is the work of existing ice streams, when
somewhat more extended than at present, or whether it is a part of the
vast glaciation imposed upon all the High Sierra during the glacial ei»()ch.
ill some instances, however, there does not seem room for doubting that
the markings were made during the past few years.

At the inmiediate foot of Mount Dana glacier, we found a numl)er of.
stones that were battered and worn and exhibited planed and scratched
surfaces, in many respects similar to the glaciated stones found in the
ancient moraines of New England. These occurred but a few feet from
the ice foot, and their bruises and scratches are, without question, the
work of the present glacier.

Glacier Movements. — That the small ice bodies of the Sierra Nevada
have a true glacial motion is apparent from the nature of the crevasses
and the curved coui-ses of the dirt bands that cross them. Measurements
of the movements of these glaciers have been made in only a few instances.
The rate of the flow of the glacier on Mount McClure was determined by
John Muir, who found that its maximum movement near the center was
about 47 inches in 46 days (from August 21 to October 0, 1872). A
more extended notice of these interesting observations is given in record-
ing "previous observations" a few pages in advance.

Glacier Mud. — The Tuolumne river has its source at the foot of
Lyell glacier. At its birth it is a rivulet, turbid with silt ground fine by
the moving ice from beneath which it issues. At the foot of the Dana
g^laoier there is a small lake confined in a rock basin, which has a peculiar
greenish-yellow color dlie to silt held in suspension. The water escapes
from this lake through a moraine piled on the rim of the basin, and is
gathered again into other depressions farther down the caflon. The
watei"S are thus filtered of matter in suspension, and the lower lakes are
clear and blue, like hundreds of other lakelets and tarns scattered over
the surrounding glaciated area. The sediment contributed to these glacial
waters is so extremely fine that it requires days and perhaps weeks to settle.

Ice Tongues. — In the steep walls of the amphitheatres overlooking
the n6vds of the glaciers here considered, there are frequently deep, nar-
row clefts leading toward the higher peaks. In many instances they are
partially filled with ice, which shoots up above the n^v^s in tapering

GLACIERS OF NORTH AMERICa..

tongues some hundreds of feet in height and at so steep an angle that it
is impossible to ascend or descend them without cutting steps. These
ice tongues are interesting features of the Sierra glaciers and are also
known to occur at the heads of similar ice streams in Wyoming.
One of them, in the shadow of a precipice, is shown on Fig. A, Plate
2. Whether they have glacial motion or not, has never been deter-
mined. They appear to have originated from the freezing of watei-s
flowing from adjacent areas, and not to have been formed entirely by
the consolidation of n6\6 snows, after the manner of true glacier ice.

Red Snow. — While Mr. Gilbert and myself were examining the
n^ve portion of the Mount Lyell glacier, we noticed that our foot-
prints in the snow had a bright pinkish tint, '.^hile the undisturbed
surface appeared white or perhaps grayish white. At the lower border
of the nev6 the color became more distinct and could be plainly seen
in the untrodden snow, and in som? instances the borders of rills
were outlined by delicate pencilings of crimson. In all cases the
" red snow " was superficial, or at most only covered by a thin layer
of fresh snow. Some of the coloring matter collected was examined
under the microscope a number of months later and found to consist
of red globules from 150 to 200 millimeters in diameter, which were
determined to be the minute algae known as Protococcus.

Surface Melting:* — Our examination of Mount Lyell glacier began
one August morning before sunrise, when the vast amphitheatre in which
the ice is cradled was hushed in the profound stillness peculiar to
mountain tops. As the sun rose above the granite spires to the
eastward and flushed the snow fields with a ruddy light, little rills started
here and there on the glacier, gradually gathering strength as the
sun's warmth increased, and by noon brooks of considerable size were
rushing down channels of ice, but sooner or later they plunged into
crevasses and were lost to sight. At midday the murmur of water
was heard everywhere over the glacier. As the chill of evening came
on the music of the streams gradually ceased, and by sunset a death-
like silence reigned over the frozen region.

That this noonday melting has more than counterbalanced the
annual additions received during the years previous to our visit, seems
evident from accounts of the former extent of the snow fields of the High
Sierra. The observations bearing upon this point are given below. From

GLACIERS OF THE SIERRA NEVADA.

all that has been learn«d concerning the fluctuations of the glaciers of
Ciilifornia, it appears that like those of Switzerland, they are subject to
periodic changes, due principally to climatic oscillations. Since their dis-
covery they have apparently not been increasing.

Pioneer Explorations in the High Sierra.

Although giving precedence to my own observations in describing the
gla(aei's of the High Sierra, it is not my intention to ignore the reports of
those who preceded me in the same field.

.rolin Muir. — An anonymous article on the " Living Glaciers of Cali-
fornia," which appeared in the Overland Monthly for Decemlxjr, 1872,
and now known to have been from the pen of John Muir, is, so far as I
tan learn, the first announcement of the existence of glaciers on the Sierra
Nevada. Mr. Muir states that in October, 1871, he was among the
nionntains of the Merced group and found a living glacier, with very-
recent moraines at its foot, from beneath which issued a stream of turbid
w liter. Furthv'r observatio.i? revealed dirt bands, crevasses, and lateral
moraines, thus leaving no doubt that the " snow bank," as it had pre-
viously been considered, was an actual glacier. Other similar ice bodies
were examined by Mr. Muir, on Mount Lyell and Mount McClure ; and
from the- top of the former peak he saw a dozen snow and ice filled
cirques on neighboring mountains.

In August, 1872, Mr. Muir placed five stakes in the glacier on Mount
McClure, for the purpose of demonstrating whether or not it ha<l true
glacial motion. Four of these stakes were ranged in line from the east
side to a point near the middle of the glacier, the fii-st being 25 yards
fiom the east bank ; the second, 94, the third, 152, and the fourth, 225
yards respectively. On observing the stakes on October 6, forty-six days
after being placed in position, it was found that No. 1 had been carried
down the glacier 11 inches ; No. 2, 18 inches ; No. 3, 34 inches ; No. 4,
47 inches. Stake No. 4 was near the middle of the glacier, and its dis-
placement was thought to iniicate the maximum motion of the ice.
Stake No. 5 was placed about midway between the head of the glacier
and No. 4. Its motion was 40 inches in forty-six days. These measure-
ments, though not as detailed and perhaps not as accurate as could be
desired, are yet sufficient to demonstrate, as claimed by Mr. Muir, that
the ice in this instance had true glacial motion. In this example, as in

GLACIEU8 OF NORTH AMERICA.

moHt noiniiil glaciers, the greatest movement wuh near the middle of the
iee Htreani.

The Mount McClure j^lacier, when visited by Mr. Muir, was approxi-
mately half a mile long and of about the same breadth in the widest part,
and was olwerved to Ix) traversed in the southeast corner by eroviusses
s(!veral yanls long, but oidy about a foot wide. The Mount Lyell
glacier, in 1872, is stated to have l)een about a mile in length by a mile
in breadth.

Mr. Muir also describes narrow, high-grade caSlons, called " devil's
slides," " devil's lanes," etc., which occur about the higher peaks and are
frequently occupied by ice. In one of these gorges the ice was found to
have a motion of a fraction of an inch a day. These small ice bodies
are what I have called " ice tongues " in describing my own observations.
It is to be lioped that further information concerning their origin and
behavior may be obtaine'd, since, so far as is known, they do not appear in
mor«! heavily glaciated regions.

In an article entitled, "In the Heart of the California Alps,"^ Mr.
Muir gives some account of the glaciei-s about Mount Kitter, combined
with enthusiastic descriptions of the magnificent scenery of the Sierra.
In another article from the same pen on " Living Glaciers of California," '^
several illustrations of glacial scenery are introduced, together with
popular descriptions of numerous ndves and ice fields.

JoHopli Lie Conte. — Professor Joseph Le Conte visited the High
Sierra during the summera of 1872 and 1873, and in company with Mr.
Muir examined the sun^ it of Mount Lyell.^ In describing- the records
of the ancient glaciei-s that once filled the Tuolumne valley, Le Conte
says, that what interested him far more than anything else seen during
his journey " was that on the main branch of the Tuolumne river, far up
among the cliffs and peaks of Mount Lyell, still exists a living glacier, in
a feeble state of activity, it is true, but certainly living." Professor Le

1 Rcribner's Monthly, vol. 20, 1880, p. 346. \

2 Harper's Magazine, vol. 61, 1875, p. 769. A brief account of the discovery of
glaciers in the Sierra Nevada, and of some of their more prominent features, may be found
in a charming book by John Muir, entitled "The Mountains of California," London, 18114.

* A portion of the observations made during these journeys was published in a paper,
" On some of the Ancient Glaciers of the Sierra," Proceedings of the California Academy of
Sciences, vol. 4, 1872, p. 169; and also in a more extended form, in the American Journal
of Science, Third Series, vol. 6, 1873, p. 325. See also Le Conte's "Elements of Geology,"
revised edition, 1882, p. «02.

GLACIEK8 OF THK HIKUKA NEVADA.

('onto accepts Mr. Mitii-'s mensurement, and concludes that "the ijlacier
iiiittlon titill i'j-iiitn."'

Mount Lyell j^hicier appears to have Imjcu more completely hidden by
snow when examined l)y l^e Contc in 1H72 than when seen by the present
writer ten yearo later. Le Conte's account, from the American Journal
of Science, referred to alK)ve, is as follows :

" Here, then, on Mount Lyell, we have now existing, not a true i/lacier,
perhaps, certainly not a typlml (/lacier (since there is no true glacitn- ice
visii)lo, but only snow and n6v^, and certainly no protmxion of an ice
tontfue beyond the snow field)^ yet, nevertheless, in some itense a ylacier,
since there is true differential motion and a well-marked terminal
moraine. It is, in fact, a glacier in feeble old age, a feeble remnant of the
Tuohnnne glaciei\ a glacier once of great proportions and j)laying ';n
important part in mountain sculpture, but now in its second childhood."

Le Conte fouuvl the surface of the snow on the n6v6 of the Lyell gla-
cier "traversed in a diiection at right angles to the slo})e by aharj) blades
of half-compacted ice about two feet apart and two, three, four, or even
live feet in height ; . . . the crests of the i^lades were not continuous,
hut irregular, both in outline and trend, very much in this respect like
ripple marks or like waves." ^ Ihe explanation offered — suggested by
Mr. T. C. Gardner — is that the blades are due to the action of the sun on
wind-ripples formed on the surface of the nev6.

Geological Survey of California. — In the publication of the Geological
Survey of California, no mention is made of existing glaciers in the Sierra
Nevada. The frontispiece of Volume 1 (Geology), showing Mount Lyell
as seen from Tuoli nine valley, and also a sketch of the summit of the
peak, forming Figure 73, indicate that the mountains were then far more
heavily mantled with snow than in 1882 and 1883. Professor J. D.
Whitney, formerly State Geologist of California, in his work on " Climatic
changes of later geological time,"'^ says, "It may be stated that there are
no glaciers in the Sierra Nevada proper and none in the Great Basin or
Kocky Mountain ranges, at least south of the parallel of 42 °. With the
exception of some recent discoveries said to have been made in 1878, in
the Wind River range (about latitude 43'^) by the U. S. Geological Sur-
veying party, of which no definite account seems as yet to have been pub-

1 American Journal of Science, Third Series, vol. 5, 1873, p. 3.32.
* Memoirs of the Museum of CompF.rative Zoology of Harvard College, vol. 7, 1882,
no. 2, p. 25.

GLACIER8 OF NORTH AMERICA.

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lished, it may be stated that there are no proper glaciers anywhere within
the limits of the United States (Alaska not included) except around the
great isolated volcanic cones of the Pacific coast. There are certainly
none in the higher portions of the Sierra Nevada or the Rocky mountains,
these most elevated regions having been sufficiently explored lo ascertain
that fact." It will be noticed that this passage was published in 1882, or
ten yefvrs later than Muir's and Le Conte's observations citeti above. On
pag'd 30 of Profess; T- Whitney's work, the notes of Messrs. King and
Gardner made in 1868, while exploring the eastern slope of Mount Hitter,
are transcribed as follows : " In a deep cul-de-sac which opens southward
on the east slope [of Mount Ritter] lies a bed of ice 200 yards wide
and about half a mile long. It has moved down from the upper end
of the gorge for 30 or 40 feet this year, leaving a deep gulf between the
vertical stone wall and the ice." In connection with these observations
Professor Whitney remarks that " it is doubtful whether these residual
masses of ice can with propriety be called glaciers."

iOlarence Kiii^r. — Mr. King also rejected Mr. Muir's observations, as
is shown by several emphatic passages in his Report of the Exploration of
the 40tli Parallel,^ but adds no new information on the subject.

Conditions Favoringr Observation. — From these quotations it will
be seen that the question of the existence of glaciers in the Sierra Nevada
nas been decided diiferently by different observers, who perhaps saw the
mountains under diverse conditions as regards their snowy covering. In
winter the glaciers are so deeply snow-covered that no one would suspect
their existence ; it is only late in summer, when the snows have decreased
to a minimum, that they are to be seen to the greatest advantage. That
Mr. Muir was correct in classing many of the snow masses among true
glaciers, has been sustained by recent studies, but the observations on
which his decision was based, were not sufficiently extended to convince
several geologists who visited the mountains when more completely snow-
covered thar. at the time the measurements referred to above were made.

Ancient Glaciers.

It is necessary in the present volume to restrict attention to living
glaciers, but in passing, I may mention that all of the higher portions of
the Siei.a Nevada, evcepting the very highest peaks and crests, were

1 Vol. 1, pp. 447, 448.

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loaded with snow during the glacial period, so as to form a vast ndv^
from which large ice streams flowed in various directions. Tlie glaciers
that went Avestward were far larger tiian those that descended the pre-
cipitous eastern escarpments. In several instances the ancient glaciers
were majestic rivera of ice 30 or 40 miles long. The present ice
l)odies are the shrunken remnants of these ancient ancestoi-s, or else mark
the beginning of a new cycle, the former glaciers having been completely
melted.

In the High Sierra to the westward of Mono lake, the more pro-
nounced topographical features resulting from the ancient glaciation are
conspicuously displayed. The broad-bottomed valley leading northward
from Mount Lyell was formerly occupied by the great Tuolumne glaciar.
This received an important tributary from the region about Mount Dana,
the path of which is deeply engraved in the topography of the country.
The glacier formed by the union of these two ice streams flowed down
the Tuolumne canon for 30 or 40 miles, with a depth of between 2000 and
3000 feet ; and it is believed to have occupied the Hetch-Hetchy valley,
but its full extent is not known. Other magnificent glaciers having their
sources about Mount Lyell and Mount Ritter descended the Merced and
San Joaquin valleys, which, like the Tuolumne caflon, were greatly modi-
fied by ice erosion. To the eastward of the divide between the drainage
to the Pacific and the Great basin, the paths of the ancient glaciers are
definitely recorded by the smoothed and rounded contours of the valley,
they occupied. Their channels are frequently fringed with lateral
moraines, which in some instances were carried beyond the mouths of the
canons and prolonged upon the plain as parallel f nbankments. This
feature is especially illustrated by the moraines at the mouths cf Bloody,
Parker, and Rush Creek caRons in Mono valley. At Bloody caflon and
Parker creek two . parate extensions of the glaciers are recorded by the
moruinal embankments. The glacier that flowed down Bloody caflon at
first a( anced upon the plain with a slight deflection to the right and
built o a pair of huge morainal embankments; subsequently the ice
retreatei it least as far as the mouth of the caflon, and then advanced a
second time with a deflection to the left, i.e. northward, and formed
a pair of parallel embankments, still larger than the first. Tv/o similar
advances of the Parker Creek glacier are recorded by the very perfect
morainal embankments still remaining. The ice stream which formerly
occupied the valley of Rush creek was by far the largest that entered the
Mono basin, and left man^ features of interest. As shown by smoothed

GLACIERS OF NORTH AMERICA.

rock surfaces and by well-preserved moraines, this glacier was over 1500
feet thick where it left the caflon: before reaching the plain it was
divided by a high rocky spur into two branches. The more southern
branch deposited terminal moraines in such a way as *to obstruct the
outlet of the valley and cause a reversal of the stream when the glacier
melted.

The evidence left by ancient glaciers in the Sierra Nevada is a part of
the records of a Great Ice age found throughout the northern half of
North America and in many other parts of the world, and falls properly
in a history of Pleistocene times. The records of this history can be
properly understood only by comparing them with similar inscriptions
now being made. The study of existing glaciers is thus a preparation
for the still greater task of deciphering the records of periods of ancient
glaciation.

CHAPTER IV.

QLACIBr.S OF NORTHERN CALIFORNIA AND THE CASCADE

MOUNTAINS.

The Sierra Nevada is considered as terminating at the northward
near the northern boundary of California ; but whether this is in reality the
limit of the disturbance that elevated the range remains to be positively
determined. The same great series of mountains so pronounced in
northern California is continued northward as a prominent topographical
feature, through Oregon and Washington far into British America.
North of California the chain had received the name of the Cascade moun-
tains, and, unlike the Sierra Nevada, is largely composed of lava sheets.
The volcanic overflows commence southward from what is generally con-
sidered as the southern extremity of the Cascade range, and form the
grandest peaks in northern California. When the region is better known,
perhaps the more southerly peaks will be classed in the same group as
Tacoraa, Jeffel'son, Hood, etc. These grand cones, the glory of the North-
west coast, have been but imperfectly explored, yet enough is known to
assure us that many of them are glacier-crowned.

Mount Shasta.

(A map of the glaciers on Mount Shasta is given on Plate 5.)

Observations by Clarence King. — The earliest account of the glaciers
of Mount Shasta is given by Clarence King, who in company with several
members of the U. S. Geological Exploration of the 40th Parallel, as-
cended the peak in September, 1870. From a report^ of this pioneer
climb, I have transcribed the portion relating to glaciers :

"On September the 11th, we climbed to the top of the lesser Sliadca
[named Shastina crater on Plate 5], a conical secondary crater jutting out
from the main mass of the mountain on its northwest side. . . . We

1 American Journal of Science, Third Series, vol. 1, 1871, p. 157. A more popular
account was published in " Mcantaineerin'' in the Sierra Nevada," by the same author.

II::;

GLACIERS OF NOKTH AMEHICA.

m !

-i -5#--*-'," ■- .-

reached the rim of the cone, and looked down into a deep gorge lying be-
tween the secondary crater and the main mass of Shasta, and saw directly
beijeath us a fine glacier [since named Whitney glacier ; see Plate 5 an<l
Figure A, Plate 6], which started almost at the very crest of the main
mountain, flowing towards us, and curving around the circular base of
our cone. Its entire lengLh in view was not less than three miles, its
width opposite our station about 4000 feet,^ the surface here and there
terribly broken in 'cascades,' and presenting all the characteristic fea-
tures of similar glaciers elsewhere. The region of the terminal moraine
was more extended than is usual in the Alps. The piles of rubbish super-
imposed upon the end of the ice indicated a much greater thickness of
the glacier in former days. After finishing our observations upon the
side crater and spending a night upon the sharp edge of its rim, oa the
following morning we climbed over the divide to the main cone, and up
to the extreme summit of Shasta, a point 14,440 feet above the sea level.
From the crest I walked out to the northern edge of a prominent spur
and looked down upon the system of three considerable glaciers, the
largest about four and one-half miles in length and two or three miles
wide. On the next day we descended on the south side of the cone,
folL ving the ordinary track by which earlier parties have made the climb.
From the moment we left the summit we encountered less and less snow,
and at no part of the journey were we able to see a glacier. An east and
west line divided the mountain into glacier-bearing and non-glacier-
bearing halves. The ascent was formerly made upon the north side,
where, as stated, there are no glaciera, and this is why able scientific
observers, like Professor Whitney and his party, should have scaled the
mountain without discovering their existence.

"Before and after the ascent of Mount Shasta, a week was given for an
examination of the southern half of the volcano. Since the earliest settle-
ment of Strawberry and Shasta valleys, there has never been such a com-
plete denudation. From June to November the snow masses were less
than they have ever been seen before. This favored greatly our geologi-
cal observations, and gave us an excellent opportunity to study the relics
of the former great neve. We explored one after another all the caiions,
whi(5h, approximately following the radius of the cone, are carved to a
greater or less depth into the lava flows. From the secondary cone around

1 J. S. Diller states that this glacier varies from 1000 to 2000 feet in width, and has
a length of two and one-fifth miles. National Geographic Monographs, vol. 1, 1805,
p. 269. _ .

(II.Al'IKRH OK XOUTH AMKHHA.

I'l.ATK 6.

SKETCH MAP OF MOUNT SHASTA, CALIFORNIA, by Gilbert Thompson.

Scale : 1 iju'h = 10,'.'00 teet.

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GLACIERS OF NORTHERN CALIFORNIA.

the eastern side of the main mass are only occasional fields of snow, and
ice bodies of a thousand or two feet long, usually quite nan-ow and lying
on the more shaded sides of the ravines. In nature and texture they are
quite similar to the true glacial ice, possessing in all cases planes of stra-
titication, which indicate the pressure of the formerly overlying masses.
There is little doubt that all the scattered snow fields that in the months
of August and September dapple the southern slopes are the relics of
glaciei's. They are found in the region of the ancient n^'ve, but extend-
ing downward into what was formerly the zone of movement.

" Upon reaching the eastern side we fovind in a deep caflon a consid-
erable glacier, having it« origin in a broad n6\6 which reached to the very
summit of the peak. The entire angle of this glacier can hardly be less
than 28°. It is one series of cascades, the whole front of the ice being
crevassed in the most interesting manner. Near the lower end, divided by
a boss of lava, it forks into two distinct bodies, one extending in an
abrupt, rounded face, no less than 900 feet in height. Below this another
branch extends down the caflon for a mile and a half, covered throughout
almost in entire length with loatbj of stones which are constantly falling
in showers from the caflon walls on either side. Indeed for a full mile
the ice is only visible in occasional spots where cavities have been
melted into its body and loads of stones have fallen in. From an archway
under the end a considerable stream flows out, milky, like the watei-s
of the Swiss glacier streams, with suspended sand. Following around
tlie eastern base of Shasta, we made our camps near the upper region
of vegetation, where the forest and perpetual snow touch each other.
A third glacier of somewhat greater extent than the one just described
was found upon the northeast slope of the mountain, and upon the
north slope one of much greater dimensions. The exploration of this
latter proved of very great interest in more ways than one. Receiving
the snow of the entire north sloj^e of the cone, it falls in a great field
covering the slope of the mountain for a breadth of about three or
four miles, reaching down the caflons between four and five miles, its
lower edge dividing into a number of lesser ice streams which occupy
the beds of the caflons. This mass is sufficiently large to partake of
the convexity of the cone, and judging from the depth of the caflons
upon the south and southeast slopes of the mountain, the thickness
cannot be less than from 1800 to 2500 feet. It is crevassed in a
series of immense chasms, some of them 2000 feet lon^^ by 30 and
even 60 feet wide. In one or two places the whole surface is broken

GLACIERS UK NOUTH AMERICA.

'{■ '

with concentric systems of fissures, and these are invaded by a set ot
radial breaks wliieh shatter the ice into a confusion of immense blocks.
Snow bridges, similar to those in the Swiss glaciei-s, are the only
means of crossing these chasms, and lend a spice of danger to the
whole examination. The region of the terminal moraines is quite
unlike that of the Alps, a larger portion of the glacier itself being
covered with loads of angular debris. The whole north face of tlie
mountain is one great body of ice interrupted by a few sharp lava
ridges whicli project above its general level. The veins of blue ice and
the planes of stratification were distinctly obseived, but neither mouJinx
nor regular dirt bands are present. Numerous streams, however, flow
over the surface of the ice, but they happen to pour into crevasses
which are at present quite wide.

" One of the most interesting of all the features of the country was,
however, the clearly defined moraines of the ancient and more widely
extended glacier system. Nearly the whole topography of the lower
part of the cone is modified by the deposition of glacial material. At
an elevation ot about 8000 feet upon the northern or snowless side
of the mountain is a gren* plateau-like terrace, 2500 or 3000 feet
wide, extending around one .ilf of the cone and composed wholly of
morainal material. Besides these, long straight or slightly curved
medial moraines jut from the mountain in all directions, not unfrequently
descending into the valley for several miles."

A brief account of the glaciers of Mount Shasta was contributed by
King to an article on gravel ridges in Merrimack valley. New Hamp-
shire, from the pen of G. F. Wright,^ in which special attention is given
to the moraines now forming on the margins of the glaciers and their
resemblance to certain glacial deposits of New England.

In the account of an ascent of Mount Shasta, published in the reports
of the Geological Survey of California,"-^ of which Professor J. D. Whitney
was director, no mention is made of the existence of glaciers. In Profes-
sor Whitney's recent work, " Climatic Changes of Later Geological Time,"
previously referred to, an account of these glaciers is introduced, but it
contains no observations in addition to those already published by King.

Observations by Gilbert Thompson. — In 1882, a topographical
survey of the region about Mount Shasta was begun by Gilbert Thompson,

1 Boston Soc. of Nat. Hist., Proc, vol. 19, 1870, p. 60.

2 Vol. 1 (Geology), pp. 332-351.

(JLACIERS OF NORTHERN CALIF(»RN1A.

(»f the U. S. Geological Survey, who, at my request, kindly furnished the
following notes and accompanying sketch map, which form a valuable
addition to the previous descriptions of the mountain :

" During a portion of the season of 1883, I was engaged in obtaining
the topographical details of Mount Shasta, California, and take {)leasure
in furnishing such information as I can concerning the glaciers now
existing on the mountain.

" Mount Shasta is a volcanic peak situated in latitude 41° 24' 30",
longitude 122° 11' 34". Its altitude, as determined by the U. S.
(ieological Survey, is 14,350 feet. It stands alone and has no connection
with neighboring mountains, none of which within a radius of 40 miles
attain two-thirds its height. The greatest length of its northwest slope,
terminated by Little Shasta valley, which has an altitude of 3000 feet, is
16 miles. The southwest slope reaches Elk flat and descends over 10,000
feet in eight miles. The highest divide to the northwest is six miles
distant and has an altitude of 0000 feet. The divide of the Sacramento
liver, ten miles to the westward, is 3500 feet above the sea. The
ordinates from the summit to the contour of 8000 feet will vary from
three to four miles in length. The point where the timber growth
receives its first check is at an elevation of 8200 feet ; the last tree,
however, so diminutive as hardly to cover the palm of one's hand, was
found at the altitude of 10,130 feet. Mount Shasta attracts the attention
at a distance of over 100 miles, and from nearer points the solemn repose
and grandeur of its isolation are impressive.

" The glacier's about the summit of Mount Shasta do not exist under
the protection of sheltering cliffs or in the depths of cafions, but occur on
the flanks of the mountains and are exposed for three-fourths of the
day to the full power of the sun. The streams that have their origin in
the melting of the snow, appear suddenly at the foot of the mountain as
rushing currents loaded with silt : these subside during the latter part of
the night and leave pools of clear water, which also gradually disap})ear.
The water again reaches the surface in unexpected places many miles
distant as immense springs. The stream channels are thus flooded once
a day during the summer ; and after the first snow, which occurs about
the first of October, no more water descends from the snow fields.

" Besides a few snow banks that last throughout the year and a few
small glaciers in the shadow of protecting cliffs, there are five ice streams
which especially invite attention. With the exception of the Whitney
glacier, which was named in honor of the former state geologist of

i J i

GLACIERS OF NORTH AMERICA.

H
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.1 ■ 1

California, these have been designated by the following Wintun names :
Konwakiton (mud glacier), Wintun (Indian tribal name), Hotlum
(Steeproek), and Bulam (great).

" The Konwakiton [McCloud] glacier is situated on the southeastern
slope and fills a basin at the head of a deep and rugged caflon. Its foot
is at the altitude of about 12,000 feet, and from beneath it a strong
stream flows down the gorge, at times di8a[)pearing Ixiueath a flooring
of ice, covered with l)oulders and debris derived from the walls that
overshadow it. On reference to the topographic sketch [Plate 3] it will
be seen that this stream falls in a cascade in the upper portion of the
caflon ; at a lower altitude it forms another beautiful waterfall about 400
feet in height. The surface of this glacier has an area of about 320,000
scjuare yards. When making the ascent by Sisson's southern foot-trail,
just as tlie weary climber turns the ' Red rocks,' at 13,000 feet altitude,
ha is forced to make a short detour on the n6v6 of this glacier, which is
'jsually separated from the wall of rock by a deep crevasse.^

" Til? Wintun glacier has an area of about 2,000,000 square yards, an
average breautu of 1000 yards, and is 3400 yards in length. In its
course it flows over two precipices and becomes greatly broken by curving
crevasses, inclosing huge rocks and pinnacles of ice. These are veritable
ice cascades of no mean proportions, and afford details of glacial structure
of great beauty and interest. Near its teiininus the glacier forms a true
ice stream confined by caflon walls, and finally terminates in an ice foot
several hundred feet high which, as indicated in the accompanying sketch,
is furrowed by numerous stream-cut channels. A close approach to the
ice wall is dangerous because of the stones and morainfil matter that at
least in summer are constantly falling as the ice melts. The glacier
terminates at an altitude of about 8000 feet, and froni It flows a
considerable stream which is always loaded with mud and silt. Some
distance below the terminus this yellow stream forms a cascade fully
400 feet in height. The walls of the caflon occupied by the lower

1 In describing this glacier .T. S. Diller states tliat tlie morainal material upon its
borders is small, and yet, of all the glaciers about Mount Shasta, it is the only one which has
left a prominent record of important changes. During a former period it was over five
miles in length and occupied an area of at least seven square miles, being twenty times its
present size. With this exception, there are no records upon the slopes of Shasta that any
of the existing glaciers were ever very much larger than at present.

The existing glaciers on Mount Shasta are but remnants of far larger Ice streams that
descended from the mountain in Pleistocene lime, and left large and well-characterized
moraines on its southwestern side some ten miles from the summit. National Geographic
Monographs, vol. 1, 1895, pp. 262, 263.

GLACIERS OP NORTHERN CALIFORNIA.

portions of this glacier, in common with nearly all the flunks of Mount
Shasta, are sombre in color and unpicturesque ; below the falls, however,
thure are many points of view that will hold the attention and excite the
enthusiasm of the traveler.

"The Hotlura glacier* is situated northward of the Wintun, and
separated from it by a series of narrow and precipitous spurs. On the
north it is bounded by a narrow crest of rock which at first glan(!c might
be tiiken to be a medial moraine. The foot of this £ iacier ends in an arc
of terminal moraines, at an altitude of 10,500 feet, which at certain
points rests upon the lower portion of the ice. A thousand streams
formed by the melting glacier find their way over and tlirough the debris
Held, and render it a treacherous terrain to explore.

" Through the n6v6 of the Hotlum glacier two ice streams may be said
to flow, one of which, in crowding past two rocky buttresses, is broken
into ])innacles of ice 50 to 60 feet in height, which are of a pearly blue
tint, and present a fantastic and beautiful spectacle. Tliu crevasses
])elow the rocks are very deep and wide. Associated with them are wells
of water of great depth having a translucent blue color; these were oval
in sliape, the longer axis being in the direction of the flow of the glacier.
Tiie glacier is 2500 yprds in length, and covera an area of about 3,200,000
square yards.

'' The Bulam glacisr, situated on the northern face of the mountain,
indicates by the magnitude of its terminal moraine tliat it carries greater
floods of debris than any of its associated ice streams. At the time of
my examination the foot of this glacier had retreated to a considerable
distance from the terminal moraines, and was divided into two flows.
The first crevasse in this glacier occurs at an elevation of about 11,000
feet, and is of great width, length, and depth. From this rent to the
terminus of the glacier the ice is oroken into rough blocks, and is deeply
seamed with fissures. The Bulam glacier is about 3200 yards in length,
and approximately 1,800,000 square yards in area. The crest of the
terminal moraine skirting its lower limit had an altitude of 10,000 feet.

"Separated from Bulam glacier by a steep, narrow ridge, as
represented on Plate 5, is Whitney glacier, a photograph of which is
given in Fig. A, Plate 6. This is the most typical ice stream on the
mountain, and originates in the n6v^ lying oii the table at the summit of

* The surface of the Hotlum glacier Ls convex from side to side, >>nd its widfi (1.23 miles)
is almost as great as its length (1.62 miles). J. S. Diller, National Geographic Monographs,
1895, vol. 1, p. 261.

rwm.TT-

IS-

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GLACIERS OF NORTH AMERICA.

the peak. "Whitney glacier, in crowding past the east base of Shastina
crater, which it has partially undermined, occasions a constant falling of
rocks and debris, and becomes broken into a multitude of blocks, whicli
are reunited as the stream flows on. The Whitney glacier is 3800
yards in length, and covers an area of 1,900,000 s(juare yards ; in Octo-
ber, 1883, its terminus was at an elevation of 9500 feet above the sea.^

"A careful examination of some of the ice bodies on the western flank
of Mount Shasta would perhaps lead to their being classed as glaciers of
secondary magnitude ; they occur on steep slopes at high altitudes, and
sill are over 700 feet in length.

"At the time of Mi. King's examination, in 1870, Mr. Watkins, of
Siui Francisco, obtained a number of i)liotographs of Mourit Shasta, from a
careful examination of which I conclude that ther j was more snow on the
mountain when they were taken than at the time of my visit in 1883 ;
this decision is also sustained by the statements of the residents in the
vicinity." ^

Mount Rainier.

(A sketch map of the glaciers on Mt. Kalnier forms Plate 7.)

In the Proceedings of the California Academy of Sciences for Mareli
6, 1871, it is stated by Professor George Davidson that Lieutenant, after-
ward General, August V. Kautz attempted the ascent of Mount Rainiei-
in 1857, but found his way barred by a great glacier. So far as can l)e
ascertained no published account of Kautz's observations has appeared.
but from Davidson's statement it seems that he first reported the exist-
ence of living glaciers in the United States. An abstract of Kautz's
manuscript account of his excursion is given by S. F. Emmons ^ iii uii

1 " The most striking feature of Whitney glacier, and that which is of the greatest
interest from a geologic point of view, is the debris it brings down tlie mountain and pilt s
ui> making a hirge terminal moraine at its lower ei.l. This moraine appears to be fully a
mile in length, measured down the slope of the mountain. Its apparent length is nuK li
greater than the real, however, from the fact that the glacier ice extends far beneath the
covering of detritus. It is so huge a pile of light-colored debris, just above the timber line,
that it is plainly visible from afar." J. S. Uillei, National Geographic Mouograplia, vol. 1,
1896. pp. 259, 260.

'^ Since the book before you was written, an instructive monograph on " Mt. Shasta, a Typi-
cal Volcano," had been published by J. S. Diller, which includes an account cf the glaciers
described above. The book referred to is one of a series entitled " National Geographic
Monographs," publish- 1 under the auspices of the National Geographic Society.

8 Journal of the ^luierican Geographical Society, vol. 9, p. 46.

I if

fl"l!|P

GLAriERs OF Xoicrii Amkkh .\

Pi.ATF n.

Fig. a. — WHITNEY GLACIER, MOUNT SHASTA, CALIFORNIA

Fig B. — summit OF MOUNT RAINIER, WASHINGTON.
.Che head of Emmons Glacier. Little Tahonia ami Gibraltar .1 the left

I' 1

■tv :r'^-' i

GLACIERS OF NORTHERN CALIFORNIA.

address before the American Geographical Society, but it contains little
information of special interest concerning the glacier seen.

Observations by S. F. Emmons. — The addr-iss referred to above,
entitled " The Volcanoes of the Pacific Coast of the United States," is
devoted, mainly to a description of an ascent of Mount Rainier by
Emmons in October, 1870, and includes many observations on the
glaciers examined during his survey of the mountain. A more detailed
account of these glaciers was contributed by Emmons to an article by
King ^ on the glaciers of the Pacific slope, and I shall quote from this in
preference to the more popular essay read before the Geographical Society :

"The glaciers of Mount Tachoma [Tacoma], or Rainier, as it is
more commonly called, form the principal sources of four important
rivers of Washington Territory, viz.: the Cowlitz, which flows into the
Columbia, and the Nisqually, Puyallup, and White rivers, Avhich empty
into Puget sound. . . . The summit of Tachoma is formed by three
peaks, a southern, an eastern, and a norihwestern ; of these the eastern
is the highest ; those on the south and nortliwest, being apparently a
few hundred feet lower, are distant about a mile and a half to two miles
from this, and separated by deep valley s. The eastern peak which would
seem to have formed originally the middle of the mountain mass, is a
crater about a quarter of a mile in diameter of very perfect circular form.
Its sides are bare for about sixty feet from the rim, below which they are
covered by a nev^ having a slope of 28*^ to 31°. This nevd, extending
from the sliouldei's of the southwestern peak to those of the northern, a
width of several miles, descends to a vertical distance of about 2000 feet
below the crater rim, an immense sheet of white granular ice having the
general form of the mountain surface, and broken only by long transverse
crevasses, one of those observed being from one to two miles in length ;
it is then divided up by the several jutting rock masses, or shoulders of
the mountain, into the Nisqually, Cowlitz, and Wliite River glaciers, fall-
ing in distinct ice cascades for about 3000 feet at very steep angles, which
sometimes approach the perpendicular. From the foot of these cascades
flow the glaciers proper at a more gentle angle, growing narrower and
sinking deeper into the mountain as they descend. From the inter-
vening spurs, which slope even more gradually, they receive many
tributary glaciers, while some of these secondary glaciers form inde-
pendent streams which only join the main river many miles below the
end of the glaciers.

* American Journal of Science, Third Series, vol. 1, 1871, p. 161.

GLACIERS OF NORTH AMERICA.

" The Nisqnally, the narrowest of the three main glaeierg ai#/>ve
tioned, has the most sinuous couree, vtirying in direction ft(rm uoalfclNsit
to south, while its lower extremity is somewhat west / ncmi^ of ^'
main peak ; it receives most of its tributaries from the «p»i ' I// tttt Mmt^
and has a comparatively regular slope iu its whole k^ngth ii&Ur^ the
cascade. There are some indications of dirt band.^ on >fo ^Mrfwm Wh^^tt
seen from a considerable elevation. Toward its low* -■ en4 A i* vdv
much broken up by transverse and longitudinal crevasses ; .*)»» is <.
the fact that it has here cut through the more yielding strata f/f v^/^«#ii^/
rock, and come upon an underlying and unconformaWe mi*m (A M/^nit*-.
The ice front [Fig- B, Plate 6] at its base is about 500 feet in height, and
the walls of lava which bound its sides rise from 1000 to 1500 feet above
the surface of the ice, generally in sheer precipi* es.

" The bed of the Cowlitz glacier is generally parallel to that of the
Nisqually, though its curves are less marked ; the ice cascades in which
each originates fall on either side of a black cliff of bedded lava and
breccia scarcely a thousand feet in horizontal thickness, while the mouths
of the glaciers, if I may be allowed the expression, are about three miles
apart. From the jutting edge of this cliff hang enormous icicles from 75
to 100 feet in length. The slope of this glacier is less regular, being
broken by subordinate ice cascades. Like the Nisqually, its lower
extremity stretches out, as it were, into the forest, the slopes on eithci-
ade, where not too steep, being covered with the mountain tir, Picea
nohilis, for several hundred feet above the level of the ice, while the
Pinns flexilis grows at least 2000 feet higher than the mouth of the
glacier.

" The general course of this glacier is south, but at its extremity it
bends to the eastAvard, apparently deflected from its course by a cliff of
older felsitic rock more resisting than the lava. The consequence of this
deflection is a predominance of longitudinal over transverse crevasses at
this point, and an unusually large moraine at its western side, whi(;h
rises several hundred feet above the surface of the glaciers, and partakes
of the character of both lateral and terminal moraines ; the main medial
morainfi of a glacier joins this near its lower end. [The crevassed and
moraine-covered surface of Cowlitz glacier is shown in Fig. A, Plate 8.]
This medial moraine proceeds from the cliff which bounds the ice-
cascade source of ihe glacier on the north, and brings down a dark
porous lava which is onh' found high up on the mountain near the crater.
The position of the medial moraine on the glac' "\^ indicate that at

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GLACIERS OF NORTHERN CALIFORNIA.

least half its mass came from the spur on the east, which is probably the
case.

" This spur, comprehending the whole mass between the Cowlitz and
White River glaciers, has the shape of a triangle, whose apex is formed
by a huge pinnacle of rock which, as its bedding indicates, once formed
part of the CwSt of the mountain, but now stands isolated, a jagged peak
rising about 3000 feet above tlie glaciera at its foot, so steep that neither
ice nor snow rests upon it. One of the tributarias to the Cowlitz glacier
from this spur brings down with it a second medial moraine, which is
traceable to the mouth of the glacier, though in general these tributary
glaciers bring no medial moraines.

"On the eastern slopes of this spur, between the two above-named
glaciers, spread secondary gl.aciera frequently of great width, but, owing
to the limited height of their initial points, of inconsiderable length.
These end generally in perpendicular cliffs overhanging the rocky amphi-
theatres at the heads of the smaller streams which flow eastward into the
Cowlitz. Looking up from the bottom o'' one of the^^" amphitheatres one
sees a semicircular wall of nearly 2000 feet of sheer rock, surmounted
by about 500 feet of ice, from under wliich small streams of water issue,
falling in silvery cascades onto the green bottom below.

" A ridge of high jagged peaks connects this spur with the main range
of the Cascade mountains in the east, and foi-ms the waterahed between
the White and Cowlitz rivre. From the connecting saddle one can look
northward across the brink of six glaciere, which all contribute to the
White river; of these the fia»t four come from tbe triangular spur
already mentioned, and are of comparatively little extent. The first two
are, however, interesting from the veined structure which they exhibit ;
they both originate in an irregularly oblong basin, having the shape
somewhat of an inclined ellipse, turning on its long diameter, the outlets
of the glacier being opposite the foci. Seen from a r^iyii point the veins
form concentric lines generally parallel to the side f the ijasin ; the
ends of those towards the center gradually l)end r(/U..d until they join
together in form of a figure S, and finally just above the outlets form
two small ellipses. They thus constantly preserve a direction at right
angles to that of the pressure exerted downward by the movement of the
ice mass, and upward by the resistance to this movement of the rock
mass between the two outlets.

" The main White River glacier, the grandest of the whole, pours
straight down from the rim of the crater in a northeasterly direction, and

GLACIEUS OF NORTH AMERICA.

1 i i

! J - i

'i J

pushes its „xtremity farther out into the valley than any of the others.
Its greatest width on the steep slope of the mountain must be four or live
miles, Harrowing towards its extremity to about a mile and a half ; its
length can be scarcely less than ten miles. The great eroding [)ower of
glacial ice is strikingly illustrated in this glacier, whic)i seem.s lu have
cut down and carried away on the northeastern side of the mountain, fully
a third of its mass. The thickness of rock cut away, as showii by the
Avails on either side, and the isolated peak at the head of the triangular
spur, in which the bed'ling of the successive flows of lava is very regular
and conftn-mable, may be estimated at somewhat over a mile. Of the
thickness of the ice of the glacier I have no data for making estimates,
though it may probably be reckoned in thousands of feet.

" It has two principal medial moraines, which, where crossed by us,
formed little mountain ridges having peaks nearly 100 feet high-. The
sources of these moraines are cliffs on the steeper mountain slope, which
seem mere black specks in the great wdiite field above ; between these are
great cascades, and below immense transverse crevasses, which we had no
time or means to visit. The surface water flows in rills and brooks on
the lower portion of the glacier, and moidins are of frequent occurrence.
We visited one double moulin where t'.vo brooks poured into two circular
wells, each about ten feet in diameter, joined together at the surface but
separated below ; Ave could not approach near enough the ii(\gQ to see the
bottom of either, but, as stones thrown in sent back no sound, judged
they must ^e very deep.

" This glacier forks near the foot of the steeper mountain slope, and
sends off a branch to the northward, which forms a large stream flowing
down to join the main stream fifteen or twenty miles below. Looking
down on this from a high, overhanging peak, we could see, as it were
under our feet, a little lake of deep blue water, about an eighth of a mih'
in diameter, standing in the brown gravel-covered ice of the end of the
glacier. On the back of the rocky spur which divides these tv/o glaciers,
a secondary glacier has scooped out a basin-shaped bed, and sends dcwii
an ice stream having all the characteristics of a true glacier, but its
ice disappears several miles above the mouths of the large glaciers on
either side. Were nothing known of the movements of glaciers, an
instance like this would seem to afford sufficient evidence that sucli
movement exists, and that gravity is the main motive power. From oui'
northern and southern points we could trace the beds of several large
glaciers to the Avest of us, Avhose upper and loAver portions only were

(II.AdKHS OK NilKTll AMKHIt A.

V\ \TK A

Fig. a. — surface OF COWLITZ GLACIER, MOUNT RAINIER, WASHINGTON,

Fig B. ICE CAVE AT THE END OF NISQUALLY GLACIER, MOUNT RAINIER.

WASHINGTON

GLACIERS OF NORTHERN CALi5C'7NIA

visible, the main body of the ice lying hidden by the high intervening
spurs.

" Ten large glaciers observed by us, and at least half as many more
hidden by the moun^aiij from our view, proceeding thus from an isolated
peak, formed a moM remarkable system, and one worthy of a careful ard
detailerl study."

A graphic ac^^ount of nn ascent of "Takhoma" [Rainier] was pub-
lished in the Atlantic Montiuy^by Geneml Hazar' Stevens, who ascended
tlifi peak in August, 1H70. Frequent reference!* are made in ihis essay
to the numerous ice streams that originate on the mountain, but no
detailed ac( ount of glacial phenomena is presented.

Recent Ascents. — Since the pioneer ascents of Mount Rainier
described above were made, the mountain has Ijeen ascended by many
tourists, and now that the route to the summit is familiar il appears that
the climb is not so difficult as at first supposed. Several excursion parties
have succeeded in reaching the summit, and have even passed the night
in the crater at the top. Ladies have been members of these expeditions
and have experienced no great fatigue or hardship from tl. ir ascent. A
graphic and entertaining account of one of the nore recent ascents, by
Rev. Ernest C. Smith, in which the luxuriance and beauty of the
vegetation clothing the lower slopes of the ma' jstic peak are contrasted
with the barrenness and desolation of die snow fields at the summit,
appeared in Appalachia,^ and is accompanied by a number of excellent
photographs of glaciers. •

The magnificence of the scenery about Mount Rainier and in the
neighboring Cascade mountains, as well as a widely spread popular
interest in the glaciers and other natural features of that region, has led
to an effort to have Congress set aside a reservation to be known as the
Washington National Park, and embi.>,cing an area of about 25 miles
square, of which the summit of Mount Rainier is the culminating point.

Mount Hood. -,.-./'S:^' ^' ['"I '-'■■"'"'[ ■P:;..C

In August, 1866, Professor A. Wood ascended Mount Hood, and
later in the year gave a short account of his observations before the Cali-
fornia A.cademy of Sciences.^ During his ascent he encountered chasms of

1 Vol. 38, 1876, p. 513. a Vol. 7, 1894, pp. 186-205.

» Proceedings, vol. 3, p. 292.

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(71*) ira-ASOS

GLACIERS OF NOllTU A.VEKICA,

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invisible depth in solid blue ice, in which the rush of subglacial streams
could be heard. Fron. the summit of the peak a deep cafion, eroded
in the steep southeast slope of the mountain, was seen to be partly
filled by a glacier. Both terminal and lateral moraines could be dis-
tinguished on the surface of the ice, and a torrent of water issued from
its terminus.

Observation by Arnold Hngrut^* — In a contribution to King's article
on the glaciers of the Pacific coast,* already referred to, the follo" 'ng ac-
count of the existing glaciers of ]Mount Hood is given by Arnold Hague:

" The cra.<er [of Mount Hood] is nearly one-half a mile wide from
east to west. The wall upon the inner side rises above the snow and ice
filling the basin some 450 feet, while upon the outer side it falls oft"
abruptly for 2000 feet. This rim of the crater is very narrow ; in many
places the crest is not more than 2 feet wide.

" Three distinct glaciers have their origin in this basin, each the
source of a stream of considerable size ; the glaciers of the White, the
Sandy, and the l^ittle Sandy rivers.

" The White River glacier heads on the eastern side of the crater and
extends in a southeasterly direction. It is barely a quarter of a mile
wide at the head, and about 2 miles long, extending 500 feet below the
line of the timber growth upon the side of the mountain.

"Near the top of the crate" a broad transverse crevasse cut-? entirely
across the glacier. Freshly fallen snow overhangs the perpendicular walls
of ice, making it exceedingly dangerous to approach. At one point only
the fissure may be crossed by an ice bridge. Further down the slope of
the glacier transverse crevasses are of frequent occurrc^ice, running nearly
parallel with each other ; most of them are, however, quite narrow. One
broad chasm presented clean, sharply cut vertical sides, for nearly 200
feet in depth, of clear deep-blue ice. Marginal crevassea, ice caves, and
caverns occur. Many of the latter are very beautiful and afford fine
opportunities for the study of the laminated and veined structure of
glacial ice.

" Very many of the phenomena attendant upon glaciers elsewhere
may be observed here. The terminal and lateral moraines are well marked
and extensive. Medial moraines, however, do rot appear, because the
glacier has no tributaries. Glacial grooving, glacial debris, and boulders
are quite characteristic.

1 American Journal of Sclsnce, Third Series, vol. 1, 1871, p. 165.

fil.AI IKItS UK Nlllll'll .\mi:kii a.

i'r.ATK 0.

■ i

FiG. A.— SUMMIT OF MOUNT BAKER, WASHINGTON.

Fig. B. — CREVASSES, JL' ECELLEWAET GLAr,ER. CANADA.
(Photograph by \Vm. Notniau Si Son.)

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GLACIEaS OF NORTHERN CALIFORNIA.

"The glacier of iSandy river is separated from that of the White
liver by a high, bare ridge, standing boldly up above the ice and dividing
the crater into two parts. The glacier descends to the southwest. It is
fed by the snow and ice of a somewhat larger area of country, and is
considerably broader than the glacier of White river. In length they
are about equal.

" An immense amount of glacial debris must be annually carried down
the streams whose waters are heavilj charged with fine, light gray trachytic
sand, brought down from above by this moving mass of ice. The
character of the rock, a brittle, porous trachytic, is such that under the
wearing action of the glacier it would be easily eroded and ground to fine
powder. The very extensive accumulation of sand banks, which are
constantly forming at the mouth of the stream where it empties into the
Columbia river, bears ample evidence of the fact.

" The Little Sandy river, a tributary of the main stream, with which
it unites a few milef5 below the base of the mountain, has its pource in
the third glacier which is formed on the western flank of the peak, separated
from the Sandy by a high wall, a somewhat broken, irregular ridge of
trachytic, which extends along the southwest slope of the mountain.

" The upper portion of the n^ve of the glacier is inclined at quite a
high angle, and is considerably fissured by broad, deep crevasses. It has
cut into the sides of the mountain a deep, narrow gorge, with bare, precip-
itous cliffs. The glacier and the valley of the Little Sandy are both
quite narrow.

" One of the mobt marked geological and topographical features of
Mount Hood and the vicinity is its very extensive system of exitinct
glaciers, which everywhere gouged out immense trough-shaped valleys,
cutting down deeply into the earlier trachytic lava flow of the old volcano.
The entire network of valleys was connected with two main glaciers,
that of Hood river on the north and the Sandy on the south. The
ancient White River glacier was undoubtedly very large, but, as far as my
observations have yet extended, had no tributaries."

Mount Baker.

Mr. E. T. Colman, of the English Alpine Club, ascended Mount
Baker in 1869. A popular account of this excursion appeared in Harper's
Magazine,^ in which snow fields, glaciers, crevasses, etc., are described in

1 Vol. 39, 1869, p. 793.

GLACIERS OF NOllTH AMEUICA.

■ i t

such a manner as to indicate that glaciers of very considerable magnitude
are now flowing down the mountain. The peak has since been ascended
by several parties. The accompanying illustratior of the summit of the
mountain is from a pliotograph taken by Professor E. S. Ingraham, of
Seattle, Washington, and sliows that glaciers of conspicuous size may
originate in unsheltered situations.

Glaciers on other Peaks of the Northwest.

Mr. J. S. Diller, of the United States Geological Survey, has made
various reconnaissances and surveys from Mount Shasta northward to the
Canadian boujidary, and has observed glaciers of considerable magnitude
on Mount Jefferson, Diamond Peak, the Three Sisters, and Mount St.
Helens. Mount Scott and Mount Thielsen were found to be free from
glacial ice. The group of peaks known as the Three Sisters is considered
by Mr. Diller as probably affording the most interesting field for glacial
studies in the United States, with the exception of Alaska. The glaciers
amid this group of peaks attracted the attention of Dr. J. S. Newberry,
while connected with the Pacific railroad surveys in 1855, but no report
of his observations has been published.

When the lofty summits of the Cascade mountains are more thoroughly
explored, it will undoubtedly be found that many more are glacier-crowned
than have been reported up to the present time. The glaciers of the
Cascade region are all of the alpine type, but are somewhat peculiar for
the reason that they radiate from isolated peaks which rise far above the
nuigliboring mountains. These peaks are all of volcanic origin, and
lingering manifestations of internal heat are to be seen in the hot springs
and fumaroles in their craters. Far down their flanks, and in some
instances for miles out on the surrounding plains, there are moraines and
other evidences showing that in Pleistocene times the climatic changes,
which caused half of the continent to be mantled in ice, were there in
operation ^Jso, and gave origin to glaciers of the same general character
as those still existing, but of far greater extenf,.

liij

CHAPTER V.

GLACIERS OF CANADA.

The CordillerrvS pass northward from the United States and traverse
the western part of Canada, Ae already stated, the general mountain
system subdivides northward and is composed of several series that are
distinct and separate both topographically and geologically. The northern
part of the system is far f:i*om being completely explored, but many
rugged peaks are known to reach the limit of perennial snow, and to be
covered in part with glaciers. About the only mountaineering that has
l)een done in Canada has btien in the Selkirk and neighboring ranges,
recently made accessible by the building of the Canadian Pacific railroad.
When explorers have conquered other mountains, there is reason to
believe from the reports of hunters, prospectoi-s, and others, that our
knowledge of the ice fields will be greatly extended, and that many fine
exarai)les of glaciers, of the alpine type, will be found clustering around
the higher summits.

'Jlie glac'ers of the Selkirk mountains are known principally from
explorations made by Rev. W. S. Green, in 1888. At least one
example, the Illece^lewaet glacier, is in sight from Glacier house on the
Canadian Pacific railroad, and has attracted the attention of thousands of
travelers from car windows. Views of this easily accessible glacier are
given on Pis. 11, 12. The scenery of the Selkirks, as seen from near the
summit of a rugged peak called Mount Sir Donald, near Glacier house,
is described by Green as follows : ^

"We were on a pinnacle of rock, according to the barometer, just
10,000 feet above the sea. On all sides were vast precipices, and down
these precipices our eyes ranged to the green, forest-clad valley of Beaver
creek, the river being visible for many miles, winding, with an infinity
of curves, 6000 feet below us.

• " Beyond the river rose a range of hills v;ith flattish plateaus on the
top, flecked with snow. Still farther to the e;istward, range rose upon
range, fading into purple and blue. Above them all the Rockies, bearing
silvery white glaciers, formed a sharply defined sky line, arid were visible

1 "Among the Selkirk Glaciers" (Macmillan & Co., London, 1890), pp. 86, 87.

GLACIEliS OF NORTH AMEKICA.

for over ir)0 miles. This wonderful panorama constituted our view to
the eastward. To the southward it was totally different ; in that direc-
tion the undulating iields of glaciers lay like a great soft white blanket
covering up everything for ten miles, beyond which other snow-seamed
crags rose, rivaling, probably in some cases surpassing, Sir Donald in
elevation. To tlie westward other ranges were to be seen, and one higli
ridge of black precipices capped by ice rose high . »ove the 'glacier and
seemed to dominate the scene. . . . Beyond the valley v,f the lUccellewati
to the northwest, some fine peaks were visible ; one dark, bare rock
pinnacle bearing n u-thwest was most striking, and, no doubt, over 10,0nf»
feet high. Our view to the northward was blocked by the last great
crags of Sir Donald, from which we were cut off by a notch 200 feet
deep. At its bottom a narrow rock arete joined the precipice below us
with the face of the final peak. Below this arite, on one side, lay the
glacier visible from Glacier house (the Illecellewaet glacier) ; and on the
eastern side, in a deep hollow, a fine glacier which we named the Sir
Donald glacier commences its course, and flows outward in beautii'id
fan-like structure, in the direction of Beaver creek."

During the explorations carried on by Greene, the Illocellewact
glacier was traversed to near its source, and several secondary glaciers
discovered. A sketch map of 500 scjuar-} miles, embracing many
rugged peaks and a score of small neve fields and glaciers, was coi:-
structed, and many photographs taken. AVith this excellent beginniii"'
it is hoped that others as well qualified for mountaineering as the dis-
tinguished writer just quoted Avill seek for new wonders among the mag-
nificent mountains of Canada.

The present writer visited the Illecellewaet glacier in the spring (if
1891, and saw something of the wonders of the Selkirks. My visit.
although brief, served to confirm the enthusiastic descriptions of that
remarkable region given by many travelers. The glaciers about tlie
higher peaks, descending, in some instances, into the deep -green
coniferous forests, and producing striking contrasts of color, are of the
same general character as the glaciei-s of the High Sierra and the Cascade
mountains. The extent of true glacial ice is greater than is presented
by the ice bodies of California, and the shining snow fields from which
it flows are broader than the similar areas on the mountains of Oregon
and Washington. In comparison with the glaciers of Ce' oral Europe.
the Selkirk glaciere lack the strongly defined, stream-like character of the
Mer de Glace, or the Gorner glacier, for example, and, in general, do not

i:. .- ...

f;LA(IKRS OK NdKTII AMEKKa

1'I.ATK 10

Fig. a. — ILLECELLEWAET GLACIER, CANADA.
(Pliotograph by Win. Kotinaii & Son.)

Fig. B. — ILLECELLEWAET GLACIER, CANADA.
(Photograph by Win. Notraan & Son.)

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OLA(;iEKS OF CANADA.

display the distinctive features of alpine glaciers so well as the archetypes
of that class of ice bodies.

Cilaciera occur farther north in Canada on the various divisions of tlie
Cordilleras, more especially in the region drained by the Stikine, and to
the northeast of Mount St. Elias ; but these are so closely associated with
the vast ice bodies of Alaska, that in the present sketch political bounda-
ries will l)e ignored and all of the glaciers of the far Northwest included
in a single chapter.

CHAPTER VI.

GLACIERS OF ALASKA.

In purchasing Alaska the United States not only acquired a vast
territory rich ii\ natural resources, but added new wondei's to her already
varied scenery. As sliown on the preceding pages, the glaciers of the
United States, previous to the purcluuse of Alaska, were by no means
insignificant, although at that time almost unheard of, and even now but
imperfectly explored. When we include Alaska and the adjacent portion
of Canada, the field for glacial study becomes almost unlimited.

The glaciers of the Alaskan region are of the alpine and piedmont
types. Masses of buried ice and frozen subsoil in the tundra region
bordering Bering sea and tha Arctic ocean and along arms of the great
rivers are not here included, and will be described in advance. All of
the true glaciers are confined to the southern portion of the territory and
depend on favorable combinations of climatic and topographical conditions
for their extent and geographical distribution. The mountains of the
Alaskan region occur mostly along its southern border, adjacent to the
Pacific ocean, and attain their greatest elevation near the 141st meridian.
The culminating peak, so far as at present known, is Mount Logan,
19,500 feet high. Second in rank stands Mount St. Elias, 18,023 feet in
elevation. These and a host of sister peaks rise from a vast n6v6 region
having a general elevation of 8000 or 9000 feet. The entire Pacific
border of Alaska is rugged and mountainous, and presents some of the
most sublime coast scenery to be found in the world. The currents of
the ocean bring warm water to the very base of these lofty mountains,
thus furnishing an evaporating surface in close proximity to cold peaks
where the vapors are condensed. About Mount St. Elias, as shown by
two seasons spent by the writer in exploring that regioii, the winds from
the south are warm and moist, and are almost invariably accompanied by
clouds and snowstorms on the mountains. The north winds are dry, and
are especially welcome, as they are frequently accompanied by clear skies
i*nd brilliant sunshine. The conditions, taken all together, are remarkably
favorable for the growth of glaciers.

GLACIERS OF ALASKA.

NarrntlvoH of Enrly Voyaifors. — The early voyagers to the southern
shore of Ahiska «aw luiiny bodies of ice, some of which we now know are
extensive gliieiera. Sir Kdwanl HeUfher, in his account of the voyage of
the Sitlpliur, niiikes Irief mention of cliffs of ice on the borders of Icy
hiiy, near the the foot of Mount St. Klia.-t.

In the account of Vancouver's voyages, Iwdies of ice, terminating in
clilTs at the water's edge, are mentioned as being numerous on the borders
of Prince \, illiam sound. In the same narrative brief dcscri[)tions are
jfivcn of an accunudation of ice in an arm of Stephen's passage, northwest
of Sitka, and ahio among the mountains along the coast opitosite Admi-
ralty island. Two large bays opening north and west from I'oiat
Couverdeen are described as terminating in solid mountains of ice rising
perpendicularly from the water's edge. Beyond the brief statement of
the presence of large masses of ice at sea level, the narratives of the bold
ex[)lorei'8 who first sailed along the wild Alaskan coast are of little interest
to the special student of glacial ])henomena. ; .

Some of the glaciers along the northern bank of Stikine river were
visited by Professor William P. lilake ^ in 1863. These ice bodies are of
the alpine type, and descend nearly to the level of the river. A popular
account of the remarkable scenery of the Stikine riv' r, in which glaciers
play a conspicuous part, was given by W. H. Bell, together with greatly
exaggerated illustrations, in Scribner's Monthly for April, 1879.

The positions of many glaciers to be seen from the decks of passing
vessels between the mouth of Stikine river and Cook's inlet, a distance
of about 1000 miles, have been indicated from time to time on the charts
published by the U. S. Coast and Geodetic Survey. Brief accounts of
the fine glaciers of Glacier bay were published by G. W. Lamplugh, in
Nature,^ in 1886, but did not serve to make the wondera of that region
generally known. Among the earlier accounts of the glaciers of Alaska,
the most noteworthy are those from the pen of Dr. W. H. Dall, the
pioneer explorer of the Yukon river and the author of a justly celebrated
work on " Alaska and its Resources."

This brief account of the sources of information relating to the
glaciers of the Alaskan region available in 3 883, when the author's sketch
of the " Glaciers of the United States " was written, brings us to the time

' Blake's observations were the earliest made in southeastern Alaska that have much
scientific value, and were recorded in the American Journal of Science, vol. 44, 1867, pp.
W-101. Republished with a map, in a report to the Secretary of State, bearing the title^
"Geographical Notes upon Russian America and the Stickeen River. Washington, 1808."

» Vol. 33, pp. 299-301.

GLACIEHS OF NORTH AMERICA.

when a wide interest was awakened in the natural features of the " Far
Noi-thwest."

'-' Kecent Exploj-ations. — Of the more recent Alaskan eyplorei-s we
are indebted especially to John Muir, who discovered the magnificent
g'acier since nam(^d in his honor, as well as many othei"s that come down
to the sea, or may be seeu from a canoe while threading the intricate
straits and bays of the southeastern portion of the territory. More
recently the glacierj of Glacier bay have been studied by Professor G.
Frederick Wright and Professor H. Fielding Reid, and the still vaster ice
streams in the regions about Mount St. Elias and Disenchantment bay
have been visited and described by a number of persons. Reference to
the principal contributions to the literature that iias grown out of these
explorations are given in the following footnote.^

Some of the glaciers flowing northward from the mountains of
southern Alaska were examined and their positions mapped by Dr. C.
Willard Hayes, of the U. S. Geological Survey, during a bold and highly
successful exploration from the Yukon to Copper river, in company with
Lieutenant Frederick Sclnvatka, in 1891.2 Other northward-flowing
glaciers were observed by E. J. Glave in 1891 ind 1892, to the north-
west of the head of Lynn canal.

In addition to the writings of the travelers referred to above, much

, 1 John Muir, " Ahaska," in Am. Geol., vcl. 11, 1893, pp. 287-299.
■ 't. F. Wright, ''The Ice Age in North America," Appleton & Co., 1889.

11. Fielding Reid, "Studies of Muir Glacier," in National Geographic Magazine
(Washington, D.C.), vol. 4, 1892, pp. 19-84.

Frederick Schwatka, " The Expedition of tht New York Times," in Ceniury Magazine,
April, 1891.

William Libbey, Jr., "Some of the Geographic Features of 3outheastern Alaska," in
Am. Geog. Soc, Bull,, 1880, pp. 279-300.

H. W. Seton-Kair, " Shores and Alps of Al'.ska," London, 1887.

H.W. Seton-Karr, "Alpine Regions of Alaska," in Roy. Geog. Soc, Free. (London),
vol. 9, pp. 2(59-285.

William Williams, " Climbing Mount St. Eiias," in Scribner's Magazine, vol. 5i 1889,
pp. 387-403.

11. W. Topliam, "An Expedition to Mount St. Elias," in the Alpine Journal (London),
vol. 14, 1889, pp. 345-371.

I. C. Russell, "An Expeditioii to Mount St. Elias" (1890), in National Geographic
Magazine (Washington, D.C), vol. 3, 1891, pp. 53-203.

I. C. Russell, "Second Expedition to Mount St. Elias," 1391, in 13th Ann. Rep. U. S.
Geol. Snrv., pp. 1-91.

John Muir, Century Magazine, vol. 60, 1896, pp. 234-247

«"An Expedition to tlie Yukon District," in National Geographic Magazine (W^asli-
ington, D.C), vol. 4, 1892, pp. 117-162.

1 ■;

GLACIERS OF AT,ASKA.

])opul..r interest in the subject here treated has lieen awakened by the
enthusiastic narratives of tourists who hav<^ made trips on the excursion
steamers sailing from Puget sound through the celebrated " inland
passage " to Taku inlet, Lynn canal, Glacier bay, etc.

From this brief summary it will be seen that the literature relating
to the glaciers of the Alaskan region is already voluminous. Instead of
attempting to give a detailed account of all the glaciers that have l)een
described, a few of the best-known examples will be selected as types.
These may be taken as representatives of the many hundred already
known, and as indicating the principal features of the probably still
greater number that have only been seen from, a distance or remain to be
discovered.

TiLF.- WATER Glaciers.

It is convenient to give a special name to glaciers which enter the
ocean and break off so as to form bergs. One should bear in mind, how-
ever, that the ice sti 3ams or ice sheets which terminate in this manner do
not differ from neighboring glaciers that fail to reach the sea, except
in the fact that they actually meet tide-water. But the striking appear-
ance of their broken extremities rising in sheer precipices above the surf
that beats against their bases, rendero them especially noteworthy and
warrants their having a special designation.

The tide-water glaciera of Alaska are the ones that claim the greatest
share of £.dmiration from tourists on account of the wonderful colorincr
and marvelous beauty of their ice cliffs and the picturesqueness of the
floating islands of ice ta which they give oi-igin. The approach to a tide-
water glacier is usually first made known by the fleet of bergs that dot
the water and chill the atmosphere. Tiiese become more numerous as
one proceeds, and many times completely cover the water before the ice
cliffs from which they came can be seen. Indeed, at times, the floating
bergs form an impenetrable pack through which it is impossible for a
vessel to advance. The vicinity of a glacier which terminates in the sea
is frequently made manifest also by the roar of avalanches, as iresh masses
of ice fall from its face and join the fleet of gleaming bergs crowding the
adjacent watei-s. The noise of the falling fragments may l)e heard many
miles, and sounds like distant thunder or the discharge of heavy guns.

When a large tide-water glacier is seen for the first time, the beholder
is fascinated by its beauty, especially if it is ilium," nated by a brilliant
sun, and learns a new lesson, for the reason that the scene is so dififei'ent

1 •

I ;

J ■

GLACIERS OF NORTH AMERICA.

from the popular idea of the appearance of glaciers, derived principally
from the well-known ice streams of Switzerland.

In going to Alaska by the customary " inland passage," through the
picturesque archipelago fringing the coast from Puget sound northward,
the first floating ice is usually seen soon after passing through Wrangell
narrows and emerging into an arm of Frederick sound. These bergs come
from a small glacier long known to the Indians as Hutli, or the thunderer,
on account of the noise produced by ice falling from its face.^ The glacier
is hidden by tlie bold, forest-covered shores of Hutli inlet, and is not seen
by travelers along the course ordinarily followed by vessels.

Proceeding northward, glimpses are obtained here and there on the
mountains of the mainland, of gleaming snow fields and of the blue of
glacial ice, rising abo"e the nearly universal green of the forest-covered
shores. The first unobstructed view of a large glacier is not had, however,
until one enters a wild fiord known as Taku inlet. On the northwest
shore of this indentation of the coast, and seen on the left as one enters
it from the sea, a stream of ice descends from the mountains and expands
into a broad, fan-like terminus at the margin of the water. This is the
Norris glacier shown on Plate 11. The mud and sand brought out by the
streams issuing from the ice have formed a fringe about its terminus, so
that it is now separated from the water of the inlet by a barren plain of
sand and mud crossed by many bifurcating streams.

Taku Glacier.

The comparative mildness of the scenery at the Norris glacier does
not prepare one for the marvels that await him a few miles beyond. At
the head of Taku inlet, and filling the gorge from side to side so as to
hold the watera of the ocean in check, is a wall of ice formed by the
extremity of a typical tide-water glacier. This is the Taku glacier, as it
has long been called by both Indians and white people. Unfortunately
an attempt has recently been made by the U. S. Coast and Geodotic
Survey^ to supplant this name by another less appropriate.

1 This glacier v. as first seen by John Muir, and the Indian name which he accepted
should be recognized. See American Geologist, vol. 2, p. 291.

8 The Hutli and Norris glaciers referred to above, a« well as several others in south-
eaf.tem Alaska, have also suffered a recent change of name on the charts of the U. S. Coast
and Geodetic Survey. I wish to protest against this useless duplication, especially when the
names of persons temporarily in political power, and for this reason simply, are put in place
of names long in use, and especially of pronounceable Indian namet'.

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GLACIEUS OF ALASKA.

Taku glacier heads far bad: in the mountains, no one knows where,
and flows toward the coast as a well-defined ice stream. It is yet in its
full strength when it reaches an arm of the sea and enters on an unequal
struggle with the waves. The wall of ice rising above the water is by
estimate 200 feet high, and nearly a mile in length. Its face is not one
sheer precipice, but is broken into buttresses and columns and diversified
by alcoves and recesses. Its crest line is irregular and serrate, and
surmounted by spires and battlements of the most varied description.
The details of the craggy slope are constantly changing and are never
the same for two successive days. In fact, marked changes occur from
hour to hour as fresh masses fall into the sea. The rapid waste, manifest
especially on summer days, is counterbalanced by the resistless onward
flow of the ice, so that but slight changes in the position of the terminus
can be recognized from year to year. Like many glaciers in the same
region its extremity is probably slowl)'- retreating, however, but no meas-
urements have been made to show the rate of recession.

The color of the fractured and cleft ice cliffs is as varied and beautiful
as their ever-changing forms. The surfaces that have been longest
exposed to the atmosphere are white and glittering, on account of the
multitude of vesicles formed in the partially melted ice ; but the clefts
and caverns reveal the intense blue of the crystal mass within. In the
deeper recesses the light issuing from the interior is of the darkest ultra-
marine, so deep that it appears almost black in contrast with the brilliant
outer surface. In the full glory of an unclouded summer day the scene
becomes resplendent with the reflected glories of the sea and sky. The
ice cliffs blaze and flash in the sunlight until one can scarcely believe that
it is an everyday, earthly scene that meets his admiring gaze. The
observer to whom such wonders are novel may well fancy that the picture
before him is but the fantasy of a dream. One is awakened from such
reverie, however, by a crash like the roar of artillery, when an avalanche
falls from the cliffs of light and is engulfed in the turbid waters below.
The white foam shot upwards by the avalanche, rises high on the iry preci-
pice, and perhaps dislodges other tottering pinnacles, which reawaken
the echoes in the neighboring mountains. After each crash, crested
waves, starting away from the scene of commotion, set numerous bergs
locking, and break in lines of foam on the adjacent shore, xloating ice
frequently whitens the entire surface of Taku inlet, and is occasionally
carried by the wayward currents far out into Stevens' passage and up
Ciastineau channel to beyond the town of Juneau.

l5;

GLACIERS OF NORTH AMERICA.

In former years Taku glacier extended far south of its present
terminus and received Norris glacier as a tributary. The former height
of the ice is clearly marked by the smoothed and rounded surfaces of the
cliffs, and by grooves and striations, for about 2000 feet above the water,
on the precipitous mountains enclosing the inlet. Above that height the
rough and angular sculpturing due to frost, rain, and rills is in marked
contrast to the ice-worn surfaces below. The glacier is still receding,
and in a decade or two will probubly have shrunken so that it will no
longer reach the inlet, but will end as Norris glacier now does, with a low
frontal slope. The waters from the glacier will then build an alluvial
plain about its extremity, and it will acquire the subdued and unpic-
turesque features characteristic of dying alpine glaciers.

MuiR Glacier.

. • (A map of Muir glacier is given on Plate 12.)

Proceeding westward from Taku inlet, the next tide-water glacier is
met with in Glacier bay. Several glaciers there pour their icy floods into
a land-locked arm of the sea. The wonders of this splendid bay, now
familiar to thousands of tourists, were unknown to civilized people
fifteen years ago. The bay and the magnificent glacier on its shores were
discovered by John Muir, the intrepid mountain climber and poetic writer
of California, in 1878. His account of the pioneer trip to Sita-da-ka^ as
the bay was called by his Indian comi)anions, has recently been i^ul)-
lished, and is a most graphic and interesting account of a canoe trip
among the islands of southeastern Alaska.^

One of the largest and at present the best-known glacier enterini,^
Glacier bay has been named Muir glacier, in honor of its discoverer. In
1886, Prof. G. Frederick Wright, with three companions, encamped for
about a month ne.ar the eastern end of the ice cliffs in which it termi-
nates, and began the study of its general features, its motions, the forma-
tion of icebergs, etc.^

The observations begun by Wright were continued and greatly

1 This brief account of explorations in southeastern Alaaka was first published as a
" folder" by the Northern Pacific Railroad Co. and afterward printed in the American Genl-
ogist, vol. 11, 1893, pp. 287-209. A revision of this charming paper, accompanied by fine
illustrations, appeared in Century Magazine, vol. 50, 1896, pp. 234-247.

* The principal account of these observations may be found in "Wright's book, " The Ice
Age in North America," Appleton & Co., 1889.

i 1

Glaciers of North ^iMERiCA.

Plate 13.

GLACIEUS OF ALASKA.

extended by Trof. H. Fielding Keid, and a nnnil)er of as!!«i8tants, in 1890,'
and again in 18'J'2.

The i>iesent writer visited Mnir glaeier in 1800, as a passenger on the
excursion steamer Queen, and spent a few hours in viewing the general
features of the region. Nearly all of the facts presented below in reference
to the more detailed cliaracteristics of the glacier, however, are taken
tiom the reports of Professoi-s Wright and Keid.

On entering Glacier bay from ley strait, one sees before him a mag-
nitii'ent inlet, the head of which is beyond the reach of vision. The bay
is 35 miles long and from six to ten miles broad. To the west rises a
group of 8now-(!lad and glacier-scored mountains, culminating in Mt.
Fiiirweather, over 15,000 feet high. The ^.e flowing from the northeast
slope of this rugged elevation reaches the western shore of Glacier bay
and forms a series of splendid tide-water glaciere. These were explored
and mapped by Ileid in 1892, but an account of them hiis not yet been
l)ul)lished, although their names and positions are sometimes roughly
indicated on charts of the bay.

As one proceeds up the Glacier bay large fields of floating ice are
usually encountered and numerous bergs are always in sight. These
floating fragments of glacial ice are driven here and there by the winds
and currents, so that the details of the arctic picture are constantly chang-
ing. At times, the ice is packed in such a way that it is difficult if not
inii)ossible for vessels to force a passage through it so ac to gain the im-
mediate vicinity of the glacier beyond.

The truly wonderful scenery of Glacier bay appeals most forcibly to
the imagination during the lengthened twilights of summer. The
latitude corresponds with that of the extreme north of Scotland. In
summer the sun declines but a few degrees below the northern horizon
and the nights are sufficiently light to reveal the white-robed mountains
in half-tones of the most delicate beauty. At such times the thousands
of bergs and the broad ice-floes are transformed by the tricks of the
mirage into shapes of the most remarkable description. Vast cities, with
colonades and ruined temples, towera and battlements, appear with mar-
velous realism where only a few moments before there was but a glassy
plain of water studded with fragments of floating ice. Sheaf-like foun-
tains and monumental shafts appear with such faithful imagery that one
is more than half inclined to yield to the delusion and believe that the

^ A report on this survey was published by Reid in the National Geographic Magazine,
Vol. 4, 1802, pp. 19-48.

!
i

OLACIEK8 OP NOUTH AMEItlCA.

apparitions are real. The weird l)eauty of the expanse of ice-freij^hted
watei-s and the cold, stern, snow-covered mountains, as well as the lively
anticipation of what is to come, make a sail on those northern watere, in
brilliant weather, an event that thrills the fancy and leaves an indelibh
picture on the memory.

On nearing the head of Glacier bay and approaching Mnir inlet, one
beholds a palisade of ice nearly two miles long and from 130 to 210 feet
high, rising from the water and uniting mountain with mountain and
forming a wall across the head of the inlet so as to hold back the waters
of the ocean. This wall of ice, shown on Plate 3, is the extremity of the
justly famed Muir glacier. As one draws near, the surface of the glacier
can be seen above and beyond the line of precipices in which it termi-
nates. The eye follows the gradually ascending plain of white to the
distant mountains, where it divides into many branches, separated by
wild, rugged peaks that stand as islands in the vast snow field.

Soundings made in the central portion of the inlet as near to the ice
front as vessels can safely venture, by estimate a thousand yards from
the base of the cliffs, gave a depth of 720 feet. The glacier extendotl
south of its present limit a few years since and occupied the site when;
this sounding was taken, and was then certainly fully one thousand feet
thick. There are reasons for believing that recent changes have not
sensibly altered the depth of the ice.

Surveys made by Reid have shown that the onward flow of the ice
near the end of the glacier, in its central portion, is seven feet per day,
and decreases to zero at the sides. ^ Knowing the width and thickness of
the ice and its iate of flow, it has been computed that about thirty million
cubic feet of ice break away each summer day and join the fleet of berths
that whiten the adjacent watera. The flow of the ice in winter is less
than in summer, but no winter measurements have been made. Judgiiiti-
from the behavior of other glaciers, it seems safe to assume that tlie
annual onward flow where the current is strongest is not less than 2000
feet.

The color of the ice wall in which the Muir glacier terminates is nf
the same marvelous character as already noted at Taku glacier. It is
especially remarkable for the deep ultramarine of the recesses. The
multitude of pinnacles and spires forming the serrate crest, as well as
each outstanding buttress of the mighty wall, are brilliant white. Tlie

1 S. Prentiss Baldwin, " Recent Changes in Muir Glacier," in American Geologist, vol,
11, pp. 307-375.

GLACIEKS OF ALASKA.

contrast in color and in form are greatest and most l)eantifnl when the
side lights of morning and evening hring out the details in strong relief,
i'lie crumbling cliffs are a ruin that is constantly renewed. The resist-
ance offered by individual features to the sun and air is brief, but new
forms take the place of tin se that succumb, and the general effect remains
tiie same. One never wearies of watching the ever-changing picture pre-
sented by the long line of cliffs in varying lights, or of studying the
formation of bergs as buttress after buttress gives way to the attacks of
the waves and topples over into the sea.

Icebergs. — The avalanches from the faces of tide-water glaciei-s take
place without warning and are fre(piently startling. The roar of the
falling masses on hot summer days is sometimes almost continuous.

Fi<i. 5. — IcEBEHo, MuiR Inlet, Alaska.

]\Iuir states that in the case of the glacier named in his honor, for twelve
consecutive hours the number of discharges loud enough to be heard a
mile or two were, by actual count, one in five or six minutes. The dis-
lodged masses falling into the sea cause great disturbances, and send the
white foam surging high up on the cliffs. On one occasion, while
traversing the surface of Muir glacier near its extremity, my attention
was attracted to a pinnacle higher than its neighbors, on the brink of the
precipice overlooking the water. While I was still gazing, it suddenly
disappeared from sight, and after a few seconds a cloud of spray rose in
its place. This is the only instance I recall in which the spray dashed
upward by falling ice rose higher than the general level of the crest of
the precipice from Avhich it was detached.

OLACIKU8 OK NOKTII AMKIIK.'A.

The icelKT^s of Gliu-ier ])ay an<l otluT portions (»f tlic Alaskiin coast
are Hinall in (!ompari.son with those of the (iieenhnul waters. Actual
measurements are not at hand ; but after several canoe trips amon<( the
rtoatin^ ice, I sliouM jud^'tj that llie hir^cr herd's are freqiu'utly loO to
200 feet, Umg by fiO to 100 feet broad, ami rise 20 to 30 feet alx)ve the
water. As they float with aliout one-seventh of their mass exposed, tlieir
total depth can be readily estimated.

In sailing >ip Muir inlet or any other arm of the sea on the wild
Alaskan shore whcni tide-water {glaciers disdiarge, one notices that tlif
bcr^s vary in character, but may be grou])ed in three cjuite well-dclincd
classes. Some are of dazzling whiteness ; others are of the color of tur-
(juoise or beryl ; others, again, are dark with dirt and stones. On watch-
ing the ice cliffs where these children of the gl{iciei*s are l)orn, we find that
when pinnacles already whitened by ex[)osure to the air fall into the sea.
they float away as white bergs. If we watch them drifting over the still
water and a[)[)caring in the distance like a fleet of glcatning sails, we note
that occasionally a white berg snddetdy turns over with great commotion
and joins the fleet having' lilue for their banner. The reason for the
change in color is that previous to turning over the porous exterior of
the submerged portion of the berg was dissolved away so as to expose the
compact ice of the interior. The sudden revei'sion of position is due to
unequal melting, which changes the center of gravity of the mass. A
cone of ice in which the height is about equal to the diameter of the base,
will float with its apex down. When a l>erg api)roaches a conical form,
the position of greatest stability is one in which the side having the
larger mass is uppermost. Bergs do not become top-heavy and turn over,
as is sometimes stated, but liecome hottom-huoyant and tend to adjust
themselves to the medium in which they float.

Blue bergs are also formed by the breaking away of portions of the
submerged ice foot of tide-water glaciers. These are frequently of laryc
size, and rise from below the surface of the water well in advance of the
visible end of the glacier. Their emergence is sudden. They bound ti>
the surface, and rising well above it carry tons of water with them. After
rocking to and fro for several minutes as if to be sure of their freedom after
centuries of imprisonment, they quiet down and float slowly away as shiiii-
mering islands of the most exquisite blue. The precise manner in which
the bottom ice of a tide-water glacier breaks off is not definitely known.
Reid has made observations in this connection at Muir glacier, and has
been led to think that the r^ )per portion of the submerged ice foot extends

(ll.A< IKUJ* i>K Nmi I II Ami iti. \.

I'laTR U.

Fig. a. ice CLIFF AT THE END OF MUIR GLACIER, ALASKA.

(Photoijraph by 11. F. Uei<l.)

q^HH^H^^^^^^^H^P^ir^^

l^^H^H^I

^H^^^H^^H

«SbhIh^^^^^^^^I

^^^^H

IQ^^P

Fig. B. — ICE CLIFF OF MUIR GLACIER AT LOW TIDE.

(PlioiiiaiiiOii bi I!, f". Kfiil.)

GLACIERS OF ALASKA.

beyond and overhangs the lower portion, for the reason that the flow of a
glacier is greater at the top than at the bottom, and also because the melt-
ing of the submei'ged ice, at least near the surface of the sea, is in excess
of the melting of the portion above water. These considerations have led
to the assumption that a longitudinal section of the extremity of a glacier
terminating in deep water would present the features indicated in the
following diagram :

Fl&. 6. — IDKAL SKCTION OP THE END OF A TiDE-WATEB GLACIER. AFTER REID.

The broken lines extending down from the surface and curving outward
are thought to represent the direction taken by fractures, v/hich permit
portions of the extremity to break off and leave an overhanging mass near
the summit of the cliff. The submerged portion would then breaF away,
and owing to its irregular form, might be thrown oittward as it rose, so
as to come to the surface some distance from the visible base of the
ice cliff.

The principal objection to this explanation, so far as can be judged
from the observations available, is that the bergs rising from below reach
*\e surface too far out from the ice cliffs. In some instances observed by
tiie present writer, they came to the surface not less than a thousand feet
from the visible ice foot. Besides, the observed rapid melting of the
submerged ice pertains to the portion within a few feet of tlie surface.
Near Muir glacitr the surface temperature of the water of JIuir inlet, as
observed \ y Prof. Wright, was 40° F. This would insure rapid melting,
but what the temperature is below the surface no one knows.

Another explanation of the formation of bergs from the submerged
jwrtion of a glacier, is that the falling of avalanches from the visible por-
tion of the ice cliff is greater than the melting of the submerged ])ortion.
A terrace-like projection of the deeply submerged ice foot is then pro-
duced, and poj'tions of the protruding base break away from time to time,
owing to their buoyancy, and rise to the surface. The conditions here
))ostulated are illustrated in the diagram on the following page.

GLACIERS OF NOKTH AMERICA.

]{ei(l objects to the hypothesis just stated, and suggests that the height
to which tlie suddenly emerging bergs rise above tlie surface of the watei'
is not so great as should be expected if they came from a depth of several
hundred feet. Until observations or computations have shown that this
objection is valid, however, it can have but little weight. Which of these
two explanations is correct, or what portion of each may be accepted with
confidence, must be determined by future observations. It would not be
difficult, or especially dangerous, to make soundings and temperatur3 cl>
servations in the central part of Muir inlet close to the visible base of thft
ice wall, and thus ascertain the slope of the submerged portion of the
glacier, and also to what depth the warm 8urfac(5 temperature extends.

The black, dirt-covered bergs occasionally seen in the vicinity of tide-
water glaciers are fragments of the bottom layei- of ice, or perhaps more
frequently portions of the sides of crevasses in which stones and dirt Iiad

1 1

Fio. 7. —Ideal Section of the End of a Tide-watek G',.a(ier.

lodged. These bergs, bearing a freight of foreign material, derive their
principal interest from the fact that they carry their loads to localities
more or less remote from their place of origin, and may drop them where
fine water-borne sediments are accumulating.

An Ancient Forest Buried beneath the Ice. — When the excursion
steamer to Glacier bay reaches within about a mile of Muir glacier, the
anchor is dropped and passengers are given an opportunity to go ashore.

On landing on either side of the inlet, the first fact that attracts the
attention of the geologist is the presence of a heavy deposit of cross-
stratified sand and gravel below the extremity of the glacier. This gravel
deposit passes beneath the glacier and is plainly of more ancient date
than the advance of the ice over it. In this deposit there are many
trunks and branches of trees ; and on the west side of the inlet there are
a score or more trunks of spruce trees, still standing as they grew, which
have been exposed by the removal of the strata in which they were
formerly buried. A photograph of this ancient forest is presented in Fiy.
B, Plate 14. The history of this deposit of sand and gravel and of tlic

GLACIEitS OF ALASKA.

forest entombed in it is in brief as follows : The glacier was formerly not
so extensive as. now, having undergone a retreat after a preceding peiiod
of marked extension, and a dense forest grew at least on the sides, if not
in the center, of the valley left exposed below its terminus. Coincident
with the retreat of the glacier and the growth of the forest there must
have been an elevation of the land which excluded the water from a por-
tion of the inlet now submerged. While the forest v/as still standing,
tJie stieams from the glacier, then terminating in the valley to the north,
brought down large quantities of gravel and sand and built up an alluvial
cone about the extremity of the ice. As this alluvial cone, which proba-
bly ended in the sea and in fact was in part a delta, increased in size, it
invaded the adjacent forest and buried the still upright trees. A subse-
quent advance of the glacier caused the ice to override the gravel with its
entombed forest. When the glacier once more retreated the deposits were
uncovered and cut away by streams flowing from the ice, so as to expose
. the trees buried within their mass. This last step in the history of the
inlet is still unfinished. The terminus of the glacier is still receding, and
as the streams flowing from it are still excavating channels through tlie
gravel, it is to be expected that additional portions of the buried forest
will be uncovered. In the moraines far up on the surface of the glacier
and on the islands of rock that project above its surface, there are bleached
and water-soaked branches and trunks of trees, which show that the now
desolate mountains bordering the ice vere formerly more or less forest-
covered.

The process by which forests about the extremities of glaciers became
buried in alluvial cones may be observed at Norris glacier and about the
expanded extremity of Davidson glacier, but is illustrated in a far more
striking manner alonf^ the bordei-s of Malaspina glacier, to be described on
a subsequent page.^

''IS^

I i

Characteristics of the Glacier's Surface. — At the locality on the
east side of Muir inlet, where excursionists usually land, the sul;glacial
gravels described above are well exposed. The border of the glacier and
the character of the ice at the extremity' where it overhangs the sea may

1 The literature bearing on the gravel deposits and buried forests at Muir glacier may be
found as follows : G. Frederick Wright, " Ice Age in North America," pp. 58-03, also in
American Geologist, vol. 8, pp. .330, 331. H. P. Cushing, American Geologipt, vol. 8, pp. 207.
I. C. Russell, American Geologist, vol. 9, pp. 190-197. II. Fielding Reid, National Geo-
graphic Magazine, vol. 4, pp. 38, 40, pi, 12. I. C. Hussell, "The Induence of Ddbris on the
Flow of Glaciers, " Jour. Geol., vol. 3, 1895, pp. 823-832.

GLACIERS OF NORTH AMERICA.

also be examined, and the broad surface of the ice that fills the valley
e.'isily reached. After walkiiig over the surface of the ice between long
lines of moraines, where it is as level and smooth as a v/ell-kept pavement,
one may climb a rocky promontory on the side of Mt. Wright, and obtain a
wide-reaching view of the remarkable scene that lies spread out before
him. There is not a tree or shrub in sight, but the crevices between the
rocks are bright with alpine flowers. The many streams of snow-covered
ice that unite to form the main trunk glacier may be distinctly traced
for a score or more of miles to their sources in the deep vallt^s and am-
phitheatres in the surrounding mountains. With the aid of the map

FiO. 8. —Side View of a ^Iedial Moraine, Muib Glacier. Photograph by H. B. Loomis.

published by Prof. Keid, reproduced on a reduced scale on Plate 12, one
can obtain a most graphic idea of the entire system of ice drainage termi-
nating in Muir inlet. The area of the actual ice surface in view is about
350 square miles. The total area from which the ice drainage is derived
is not far from 800 square miles.

Looking down on the glacier from an elevated station, for the first
time, one is filled with awe and wonder at the vastness of the panorama so
clearly and distinctly visible. The rough broken ice with shining pinna-
cles overlooking blue crevasses, in the central portion of tLo stream, just
before it makes its final plunge into the sea, reveals the line of greatest
movement. It was in this call but impossible portion of the glacier that
Prof. Reid after great exertion placed his signals in 1891, and measured

(iLAflKHS <IK XuIlTII AMKKK A.

I'LATK 14.

Fig. a. — surface OF MUIR GLACIER; WITH WHITE GLACIER, A

TRIBUTARY.

(Photograplr by H. 1"'. Ueid.)

Fig. B.— buried FOREST AND GRAVEL DEPOSITS AT END OF

MUIR GLACIER.

(Pliotogrnph hy JI. F. Keid.)

the

iiol

1)01

lull

SIM
Avll
JK);
tlil
Stil

rea
she
wh

sta
tlil
anc

var
fillt
tail

cur
twc
beg
apt
reg
bar:

onl

By'

ice
slop

sho
Wh
fina
exp
stre

GLACIERS OF ALASKA.

the strength of the glacial current. The actual center of the glacier was
not reached, however^ as the ice was there so shattered as to he impassable.

The number of narrow dirt-covered ridges running parallel with the
border of the' glacier, and extending from the summits of the cliffs over-
hanging the sea, up the surface until they disappear beneath the neve
snow of the higher regions, or reach rocky islands in the glacier from
which they originate,, mark the border of the individual ice streams com-
posing the main and highly com[)ound central trunk in which all of the
tributaries unite. We note, also, that the long, narrow moraine belts
stand in relief above the general surface like railroad embankments. In
reality these huge piles of stones and earth, as they appear, are but a thin
sheathing, covering ridges of ice which they have preserved from melting
while the general surface wasted away.

Fully a score of secondary glaciers are in sight from the elevated
station on which the reader is supposed to stand, but there are still other
tributaries to the eastward that are concealed from view by Mt. Wright
and neighboring elevations.

With the accompanying map in hand, one may readily identify the
various features of the vast landscape. One evident fact is that the ice
fills the valleys to a depth of many hundred feet, leaving the steep moun-
tain sides above the established grade almost free of snow.

The medial moraines coming from the northeast in broad graceful
curves, as indicated on the map, do not seem to be formed by the union of
two marginal moraines, as is the rule in such instances, but appear to
begin suddenly in the region bordering Main and Berg lakes. This
apnarent anomaly is due to the fact that the secondary glaciers in that
region are wasting away and have already melted at their sources and left
barren boulder-strewn areas, now filled in part with water held in check
by ice still filling the main valley. These secondary glaciers have not
only been beheaded^ but a reverse flow initiated in the portion remaining.
By observing the contour lines drawn oii the map where they cross the
ice in Main valley, it will be seen that the surface of the glacier has a
slope both east and west from a divide.

The most remarkable feature in the behavior of the medial moraines
shown on the map is the union of several trains of stones and dirt on
White glacier and on Southeast tributary, where they come together and
finally form a single ridge. This peculiar phenomenon has not been fully
explained, but is probably due to a decrease in volume of the several
streams by reason of their jpelting. ^

GLACIERS OF NORTH AMERICA.

Dying glacier, on the west side of Muir inlet, presents decisive evi-
dence of recent retreat. Its surface is almost completely concealed
beneath dirt and stones, and the valley l»olow its present terminus has
recently l>een abandoned by th<' 'ce and is barren and desolate. Similai'
evidence of the general waste and recession that is affecting many of tlu;
glaciers o'' Alaska is also manifest in Dirt glacier. In this case the ice is
so completely concealed by a superficial sheet of debris that one not familiar
with the various phases of glacial waste would scarcely recognize it as a
f^lacier at all. It appeai-s more like a plowed field washed by winter
storms than like an ice body.

Recent Recession. — In addition to the qualitative evidence of general
glacial retreat indicated above, we have direct quantitative measures of
the recession of the ice cliffs in which Muir glacier ends. As observed
by Wright and Reid, Muir glacier has in recent years been both of greater
and of less extent than at present. The fact of a former shrinking is shown
by an abundance of evidence. The bases of the enclosing mountains and
the summits of the rocky islands in the glacier are smoothed and striated,
and have boulders of various kinds of rocks scattered over their slopes.
These results of ice action reach, in vertical height, about 2000 feet on the
sides of the mountain near where Muir glacier now terminates, and extend
far south along the shore of Glacier bay. The absence of trees, and the
general desolation of the borders of Glacier bay and of all the valleys open-
ing from it, are in marked contrast to the densely wooded shores of
neighboring inlets, and are due to the recent occupation of the region by
glacial ice.

If the ice at the locality where Muir glacier now ends were 2000 feet
thicker than at present, making its total depth about 3000 feet, as was the
case when its maximum extension occurred, it is evident that its terminus
would be far to the south. At the time of the greatest extension, all of
the glaciers now pouring into Glacier bay were united and formed a trunk
stream which flowed southward and probably united with other similar ice
sheets so as to form a piedmont glacier. This great extension was during
one of the later maxima of the glacial epoch. There is evidence, how-
ever, of an extension of the ice far beyond its present limits within the
past one hundred years.

In 1794, Vancouver sailed through Icy strait and failed to discover
what is now known as Glacier bay, but states that a wall of ice existed at
its present entrance. The evidence that Va^co'ivcr actually saw the

GLACIERS OF ALASKA.

Uirminus of the Glacier bay ice sheet is not conclusive, as his description
would apply equally well to a jam of bergs closing the entrance of the
inlet. When taken in connection with similar evidence of ice extension
in Disenchantment bay, 150 miles to the west, it seems reasonable to
.suppose, however, that at the time of Vancouver's visit Glacier Iwiy was
actually occupied by a great glacier.

Olwervations on the position of the terminus of Muir glacier made by
Muir in 1879,8how that the ice then extended about one and three-fourths
miles, and when seen by Wright in 1886, about one mile below the posi-
tion of its extremity when surveyed by Reid in 1890. Still more recent
observations indicate that this rapid retreat, with many variations in the
trend of the ice cliffs, is still in progress.^

Glaciers on the West Side of Glacier Bay.

But little is known of the glaciera entering Glacier bay from the west,
excepting that they are of large size and set vast quantities of ice afloat.
The thunder of avalanches in that region may be heard while ascending
the bay, but the ice floes about the fronts of the glaciers are usually so
closely packed that, so far as I have been enabled to learn, no vessel has
made a near approach to them. Muir explored this portion of tlie bay in
a canoe, and states that next to Muir glacier, the largest ice stream enter-
ing it is at the northwestern extension. The glacier referred to is proba-
bly the one now known as Pacific glacier. As described by Muir, " its
broad, majestic current, fed by unnumbered tributaries, is divided at the
front by an island, and from its long, blue wall the icebergs plunge and
roar in one eternal storm, sounding day and night, winter and summer,
and from century to century."

The glaciers on the west side of Glacier bay present a most attractive
field for study and are within easy reach of lines of summer travel.
Results as valuable as those gathered by Wright and Reid might there be
had during one or two summer excursions.^

Another tide-water glacier is reported to exist at the head of Dundas
bay, opening into Cross sound to the west of Glacier bay, but there are no
authentic observations available concerning its character and extent.

^ A discussion of observations bearing on the rate of retreat of Muir glacier is given by
Reid in The National Geographic Magazine, Washington, D.C., vol. 4, 1802, pp. 37-42.

' Since this was written I have learned that Reid made a study of the glaciers on ^he
west side of Glacier bay in 1892. An account of these observations, together with a valuable
map, showing all of the glaciers that reach the sea in that region, will soon be published in
the 10th Annual Report of the U. S. Geological Survey.

OLACIEK8 OF NOUTH AMEKICA.

Proceeding Wtjstward from CrosH sound along the Hublime Fairweathei'
coaat, the next ghicier met witli which discharges directly into the sea, is
at the head of Disenchantment bay, 150 miles from Muir glacier and about
60 miles eastward of Mount St. Elias.

Glaciehs of Disenchantment Bay.

(See map forming Plate 17.)

On the shore of the narrow, winding inlet at the head of Yakutat bay,
known as Disenchantment bay, there are three glaciei-s which enter the
water and give origin to bergs, and at lejist a score of lesser ice streams
that have recently shrunken and are now separated from the bay by
narrow and exceedingly barren bouhler-strewn areas. On the higher
poitions of the mountains enclosing this land-locked arm of the sea, there
are hundreds of al[)ine glaciers descending from shining snow fields. The
tide-water glaciers referred to are the Turner, Hubbard, and Nunatak.
The positions of their extremities are shown approximately on the sketch
map forming Plate 17.

Turner, Hubbnr<l, and Nunatak Glaciers. — The best general idea
of the ice streams discharging into Disenchantment bay can be obtained
from the islands that break its surface. The largest of these, named
Haenke island in honor of the botanists of Malaspina's expedition, durinpf
which portions of the southern coast of Alaska were explored in 1792, was
visited by the write • in 1890, and a landing effected with some difficulty
through the closely packed icebergs that beset its shores. Its bordere are
high and rocky. Its surface has been worn into rounded and subdued
contour by the ice that once flowed over it, with a depth of about 2000
feet. The domes of light-colored granite are smooth and polished, and
give abundait evidence of the stubborn resistance they offer to the ice
current. Tne summit of the island is about 800 feet above the surround-
ing waters.

The follo'' :ng account of the tide-water glaciers to be seen from
Haenke island is taken from the report of my first expedition to Mount
St. Elias : 1

" Reaching the topmost dome of Haenke island, a wonderful panorama
of snow-covered mountains, glaciers, and icebergs lay before us. Tlu;
island occupies the position of the stage in a vast amphitheatre; the

1 National Geographic Magazine, Washington, D.C., vol. 3, pp. 08, 99.

■' 3 1 1

0LACIEU8 OF ALASKA.

spectator were hoary mountain peaks, each a monarch robed in ermine
and bidding detiance to the ceaseless war of the elements. How insignifi-
cant the wanderer who confronts such an audience, and how weak his
effort to descrilH) snch a scene !

" From a wild cliff-enclosed valley toward the north, guarded by tower-
ing pinnacles and massive cliffs, flows a great glacier, the fountains of
which are far back in the heart of the mountains Ixjyond the reach of
vision. Having vainly sought an Indian name for this ice stream I
clnistened it Dalton [Turner] glacier.* The glacier is greatly shattered and
])iiuiacle(l in descending its steej) channel, and on reaching the sea it ex-
jjiinds into a broad ice foot. The last steej) descent is made just l)efore
gaining the water, and is marked by crevasses and pinnacles of magnifi-.
cent proportions and beautiful color. This is one of the few glaciei-s of the
Mount St. Elias region that has well-tlefined medial and lateral moraines.
At the base of the cliffs on the western side there is a broad lateral moraine,
and in the center, looking like a winding road leading up the glacier,
runs a triple-banded ribbon of debris, forming a typical medial moraine.
The morainal material carried by the glacier is at last deposited in the sea
at its foot or floated away by icebergs and scattered far and wide over the
l)()ttom of Disenchantment and Yakutat bays.

" The glacier expands on entering the water, as is the habit of all
glacier's of clear ice when unconfined, and ends in magnificent ice cliffs
some two miles in length. The water dashing against the bases of the
cliffs dissolves them away, and the tide tends to raise and lower the
expanded ice foot. The result of these agencies and of the onward flow
of the ice itself is to cause huge masses, sometimes reaching from summit
to base of the cliffs, to topple over into the sea with a tremendous
crash. Owing to the distance of the glacier from Haenke island, we
could see the ice fall long before the roar it caused reached our eai"8 ; the
cliffs separated and huge masses seemed to sink into the sea without a
sound ; the spray thrown up as the blue pinnacles disappeared ascended
like gleaming rockets, sometimes as high as the tops of the cliffs, and then
fell back in silent cataracts of foam. Then a noise as of a cannonade
came booming across the waters and echoing from cliff to cliff. The roar
of the glacier continues all day when the air is warm and the sun is brght,
and is most pronounced when the summer days are finest. Sometimes
roar succeeds roar like artillery fire, and the salutes were answered, gun

* The U. S. Board of Geographic Names has for sufficient reason authorized the substi-
tut ion of the name of J. H. Ihiruer for the name originally given by me.

■r

! ' 11

I';'

OLACIKItb OF NUKTH AMKItlCA.

for gun, by the greut 'iul)l)iinl gliu i«!r, which [uniVH itH flood of ice into
the fiord a few miles uortlieivst of where Turner glacier terminates. This
ice stream, the most magnilicent of the tide-water glaciers of Alaska yet
discovered (with the exception, as is now known, of the southwest pro-
longation of Malaspina glacier), and a towering mountain peak from which
it receives a large [)art of its drainage, were named in honor of (Jardiucr
(f. IIul)l)ard, president of the Natioiial (ieographic Society. A dark head-
hmd on the shore of the mainland to the right slnits off the full view ot
the glacier, hut formed a strongly drawn foreground, which enhanced the
pictures(iue effect of the scenery."

A year later, on September 0, I renewed the exploration of Disenchant-
jiient bay. With two c()m[)anions I rowed northward near the base of the
cliff's to the east of Ilaenke island. We found the bay quite free from
floating ice, although the bergs were densely packed against the western
snore. The morning was bright and fresh after prolonged storms, but
dense cloud masses still clung to the coM summits of the higher moun-
tains. The vegetation on the rugged shores became more and more
stunted as we advanced. Before reaching Osier island, situated at tlic
abrupt angle formed where Disenchantment bay turns eastward, even tlic
more sheltered gorges were barren and desolate down to within 100 fctt
of the water's edge. At Osier island there is an outstanding cape, form-
ing an island at high tide, which is covered with a dense growth of
stunted willows, — hence its name, — and affords a fine station for ol)-
serving the magnificence of the surrounding glaciers and mountains.

Seated among the willows on the summit of the island, we noted the
luxuriance of the grasses at our feet and the profusion of dwarf rasp-
berries, Jiubus arctica, which were just ripening. We were at the actual
border of vegetation. All to the north was stern, wild, and desolate.
Cliffs and precipices without the so^u^ning tints of plant life rose precij)i-
tously from the water's edge tc ':l>i. snow-covered slopes which disa^)-
peared in the clouds. Just across the inlet, perhaps two miles distant,
rose the ice cliffs of Hubbar ' glacier to a height, by estimate, of 250 to
300 feet. Each shining buttress and glittering pinnacle, as seen in the
early morning light, was of the purest white or of the most delicate blue,
while the caves and deep recesses were of such a deep blue that they
appeared black in contrast with the sheen of the surfaces where the sun-
light fell. Reports like the roar of heavy guns frequently attracted our
attention to the cliffs, but owing to their distance, the avalanches causiut,'
the disturbances usually disappeared before the sound reached our station.

ULAdKHIt or NollTII A.MKUUA.

Tlatk is.

Fig. a —HUBBARD GLACIER, DISENCHANT^;FNT BAY, ALASKA.
«I*rii\i'n from n I'liotograiili.)

Fig. B.- glaciated SURFACE OF HAENKE ISLAND, DISENCHANTMENT BAY,

ALASKA, LOOKING NORTH.

GLACIKRS OF ALASKA.

Following the reports came the waves generated by the falling ice masses,
which broke on the beach in long lines of foam. The surface of the
bay was unruffled by wii;d, and the breaking of these occasional surges
seemed a phenomenon wiihout a cause, until their connection with the
masses of ice falling from the glacier was suggested.

Both Turner and Hubbard glaciers are in full view from Osier island,
as are also many lessci' ice streams that do not reach the sea. The lower
extremity of all of the smaller glaciers that approach the sea are com-
l)le<^ely concealed beneath brown and barren moraines. Many times these
sheets of debris are so uniform, and merge with the surrounding boulder-
covered area so gradually, that it is impossible to tell where the glaciers
actually terminate.

During our exploration of Disenchantment bay, we sailed eastwaid
along the coast to where the inlet abrujjtly clianges its coui-se and extends
southward through the mountains and into the flat, fo^ast-covered alluvial
plain bordering the Pacific. At the angle where the bay makes this sharp
bend there is a high, rocky promontory of glacier-burnished rock, which I
'laraed Cape Enchantment. From the summit of this headland another
splendid view of the mountain-enclosed bay was obtained. At the extreme
eastern end of the easc-and-west reach of the bay, a large glacier comes
down to the water, and breaking off sends many bergs adrift. This
glacier was not explored, but evidently flows from snow fields far back in
the highlands. Near where it discharges into the bay it is divided by a
rounded dome of rock which rises through the ice and forms a nunatak,
as such islands in ice are cjilled in Greenland, which suggested the name
Nunatak glacier.

Many other facts of interest to the student of glaciers ma}'^ be observed
from Haenke and Osier islands and from Cape Enchantment, some of
which are described elsewhere.^ As our immediate interest is concen-
trated on tide-water glaciers we must pass on, in our fireside travels, to the
next example, to the west of Yakutat bay, which is by far the most
magnificent of its class yet found in Alaska.

Icy Cape.

All of the tide-water glaciers of Alaska referred to above reach the
waters of the ocean at the heads of deep inlets or fiords, and are sur-

i"An Expedition to Mount St. Elias, 1800," National Geograpiiic Magazine, vol. A,
1391, pp. 53-203. " Second Expedition to Mount St. Ellas, 1891," 13th Annual Report U.
S. Geological Survey, pp. 1-01.

GLACIERS OF NORTH AMERICA.

rounded by precipitous mountains. At Icy cape, however, the western
lobe of Malaspina glacier advances boldly into the Pacific and meets the
full force of its surges. There are no highlands bordering the ocean foi-
scores of miles on either hand, and the glittering wall of ice rises above
ihe foaming waters to a height not less than three hundred feet. The
general appearance of these great precipices of ice when seen at a distance
recall the chalk cliffs of Dover, but are more varied in color and far more
impressive. The heavy waves of the Pacific undermine the cliffs, and
great masses of ice are almost continually falling into the sea. Their
thunder is seldom silent, and on still days can be heard distinctly at a
distance of twenty miles.

The scene presented by Icy cape, with its white girdle of floating
bergs, especially when a storm is raging and the heavy billows add their
roar to the thunder of the avalanches, is one of the wildest and grandest
ihat can be imagined.

The ice ciiffs formed where Malaspina glacier enters the sea prese .t
only one of th^ many interesting features of the great ice sheet . r
southern base of Mount St. Elias. This great glacier is the type of pied-
mont ice sheets, and will be described a few pages in advance.

To the west of Icy cape there are other great glaciei-s intervening be-
tween the mountains and the sea. The largest of these, known as Bering
glacier, is probably of the same character as the Malaspina ice sheet, but no
one has trodden its surface and scarcely anything is known concerning
even its more general features. So ^ar as has been reported, there are no
glaciers to the west of Icy cape which actually reach the sea, and there-
fore none that require mention at the present time.

Alpine Glaciers.

Several of the alpine glaciers of Alaska which enter the sea have
already been partially descriljed under the head of tide-water glaciers; but
there are others, numbering many hundred and probably several thou-
sand, that terminate before reaching the sea, and belong to the class heie
considered. Nearly all of the higher valleys and degressions among j;lu'
mountains from Stikine river northward and westward to Cook's inlet are
filled with n6vd snows and drained by ice streams. This great glacial
belt, nearly a thousand miles in length, has its maximum width in the
vicinity of Mounts Fairweather, Logan, and St. Elias, where it is from 80
to 100 miles wide. Over this central territory, about 350 miles in length,

GLACIERS OF ALASKA.

every depression at an elevation of over a thousand feet, is filled with
snow and ice, making one confluent neve field, through which the higher
and more rugged peaks rise like barren islands. An extended view of
tliis wild country, where so many glaciers have their sources, was obtained
l)y the writer in August, 1891, from the northern side of Mount St. Elias,
and may be taken as representing the general character of the entire
region between Lynn canal and Copper river. My report on the jjortion
of the climb referred to is as follows ^ :

" I was now so near the crest of the divide that only a few yards re-
mained before I should be able to see the country to the north, a vast
region which no 'one had ^"^et beheld. As I passed on, I pictured in fancy
its character. Having previously crossed this same system of mountains
at the head of Lynn canal and traversed the country north of it, I imagined
I should behold a similar region north of Mount St. Elias. I expected to
see a comparatively low, forested country, stretching away to the north,
with lakes and rivers and perhaps some signs of human habitation ; but I
was entirely mistaken. What met my astonished gaze was a vast snow-
covered region, limitless in expanse, through which hundreds and perhaps
thousands of barren, angular mountain peaks projected. There was not a
stream, not a lake, and not a vestige of vegetation of any kind in sight.
A more desolate or a more utterly lifeless land one never beheld. Vast
smooth snow surfaces, without crevasses, .'itretched away to limitless
distances, broken only by jagged and angular mountain peaks. The
general elevation of the snow surface is about 8000 feet, and the moun-
tiiins piercing it are from 10,000 to 12,000 feet, or more, in altitude above
the sea. Northward I could see every detail in tl /^ forbidding landscape
for miles and miles. The most remote peaks in view in that direction
were 40 or 50 miles distant. To the southeast rose Mount Fairweather,
ilainly distinguishable, although 200 miles away. About an equal dis-
:^ce to the northwest are two prominent mountain ranges, the highest
[h aks of which appeared as lofty as Mount Fairweather. These must be
in the vicinity of Mount Wrangel, but their summits were unclouded
and gave no token of volcanic activity.

"I could look down upon the coast about Yakutjit bay and distin-
i^uish each familiar island and headland. The dark shade on the shore,
too distant to reveal its nature, I knew was due to. the dense forests on
the lowlands between the mountains and the sea. This was the only

1 " Second.Expedition to Mount St. Elir ?, 1801," in 13th Annual Report U. S. Geologi-
cal Survey, 1891-02, pp. 47, 48.

GLACIEIIS OF NOUTII AMERICA.

indication of vegetation in all the vast landscape that lay spread out
beneath my feet. The few rocks near at hand, which projected above the
snow, were without the familiar tints of mosses and lichens. Even the
ravens which sometimes haunt the higher mountains were nowhere to be
seen. Utter desolation claimed the entire land.

" The view to the north called to mind the pictures given by Arctic
explorers of the borders of the great Greenland ice sheet, where rocky
islands, known as ' nvniataks,' alone break the monotony of the boundless
sea of ice. The region before me was a land of nunataks."

^t is impossible to give a detailed account of the great number of
ali)ine glaciers in southern- Alaska, but a few of those "best known may
be described, and serve as examples of the class to which they belong.

.iL

Seward Glacier. — The largest alpine glacier thus far discovered in
North America, exclusive of the Greenland region, has its source in the
neighborhood of Moun*: Logan, and was named the Seward glacier in
honor of the distinguished Secretary, to, whom we are indebted for the
jnirchase of Alaska. It has many tributaries in the rugged region where
it rises, and flows southward like a broad sluggish river to the ?Ialasi)ina
glacier, of which it is one of the principal feedei-s. A portion of this great
glacier and some of its branches, is shown on the map forming Plate 16,
but the entire area it drains has not been explored. A view of the glacier
and of many of its tributaries was had b}' the writer from the summit of
the Pinnacle cliffs, which embraced fully fifty miles of the ice stream and
nipuy of the magnificent peaks from which it receives the snow drainage.
The jjlacier in its narrowest part is by estimate three miles broad. Ex-
cept at a few places where it passes rocky precipices, its sides are poorly
defined, as it merges with broad snow fields in such a manner that only
the crevassed and broken condition of the snow en t'.e sides of the more
rapidly flowing central portion serves to define its boundaries. At tliree
localities where it descends steep slopes due to faults in the rocks beneath,
the ice is broken and stands in pinnacles between blue crevasses, but
these ice falls are not as high or as impressive as in some of the neighbor-
ing glaciers. The firat or upper fall, at the east end of the Corwin cliffs,
is an abrupt descent of several hundred feet, and from the west appears
like a huge wall crossing the glacier from side to side. Both above and
below the fall the surface appears nearly level for several miles, and is as
smooth and even as a snow-covered meadow. Some ten mil^s below t\\v
upper fall is the second ice cascade, or what may more property be called

GLACIEUS OF ALASKA.

an ice rapid. The ice is there greatly crevassed for several miles, but
letains a generally level surface and its remarkably stream-like character.
These rapids occur where the ice flows across an escarpment formed by a
prolongation of Pinnacle cliffs.

On looking down on the rapids from a commanding summit, one be-
holds a series of breaks in the ice which are small at first and trend up
stream from each margin of the central current. The first breaks to be
recognized are mere cracks, and although approaching the center of the
glacier, do not meet. A few rods below, the cracks are a little broader,
and meet in the center of the glacier so as to form a continuous break from
side to side. The fissures from either side meet at an angle of perhaps 50
or 60 degrees, and form V-shaped figures, with their apexes pointing up
stream. A few rods farther down, the crevasses cross the glacier in nearly
straight lines, and then begin to bow in the middle on account of tlie more
rapid central current. The more rapid flow of the central portion of the
stream is indicated throughout the descent by the curvature of the crevasses.
After becoming gently curved down stream they pass into semilunar
gashes, widest in the center and tapering towards the end. Finally, near
the lower end of the rapid, the crescents liecome sharply bent in the
center, and the bending increases until the gashes from either side unite
at an angle of perhaps 30 degrees, and again form V-shaped figures, this
time pointing down stream. With these progressive changes in the direc-
tion and size of the crevasses, cross fractures are formed, which become
more and more numerous in the central and lower portions of the rapid.
The parallel V-shaped gashes aiTanged in regular order, one above
another, impart to the central part of the glacier a peculiar wavy appear-
ance when seen from a distance, resembling the changeable figures to be seen
in " watered ribbon." With these changes in the direction and size of the
crevasses there are accompanying changes in color. The cracks in the
upper part of the rapids are in a white surface, but the ice forming their
walls is dark blue. At a distance the breaks appear as blue lines on the
snow. Lower down stream, where the cracks become wider, broad Avhite
tables are left between them. As cross fractures are formed, the sides of
the tables crumble away and portions falling into tl'.e crevasses tend to fill
tliem up. As the surface melts, the surfaces of the tables lose their purity
and become dust-covered and yellowish, but the broken blocks in the
crevasses expose fresh material and retain their whiteness. At this stage,
the sidas of the crevasses change from blue to white. The positions of i;he
l)reaT,.8 are then marked by broad, white bands on a gray surface. Far

100

GLACIERS OF NORTH AMEIilCA.

ill '.

do'v/i the rapids, where the lower set of V-shaped crevasses are most pro-
nounced, the tables have crumbled away and filled the intervening gulfs,
so that their positions .are distinguished solely by differences in color.
The scars of the crevasses formed above are shown by Avhite bands on a
dark, dust and dirt covered surface, instead of by blue m.arkings on a white
surface, as at the beginning. Before the lower ice fall is reached where
the Seward glacier makes a final plunge before joining the Malaspina
glacier, nearly all traces of the tens of thousands of fissures formed above
have disappeared.

An observer standing on one of the commanding summits at the western
end of Pinnacle cliffs can see the broad surface of Seward glacier from
the upper falls to where it disappears over the brink of the lower fall on
the border of Malaspina glacier. The glacier from side to side then drops
from sight, and the wild assemblage of pinnacles that occui-s below is only
indicated by a line of blue where the final plunge begins. Such a view
suggests the appearance of Niagara when seen from above the hoi-seshoe
fall, but the far mightier cascade in the Seward glacier is silent and
apparently motionless.

The writer was encamped for several days in July, 1890, on a narrow
crest of rock barely wide enough to support a small tent, which breaks
through the snow at the western end of Pinnacle cliffs ; and on the imme-
diate border of the rapids is Seward glacier. The murmur of water flow-
ing through icy channels could be heard far beneath the surface of the
glacier, but no streams traversed its broken surface. Crashes and rum-
bling noises produced by the slowly movinof mass frequently attracted our
attention, and sometimes at night Ave would be av/pkened by a dull, heavy
thud, accompanied by a trembling of the rocks on whicli v/e slept, and
producing the effect of a slight earthquake shock. Occasionally a tower-
ing pinnacle of ice on the extremely rugged surface of the glacier in front
of our tent would fall with a startling crash and be engulfed in an ad-
jacent crevass. These evidences of change showed that the apparently
motionless ice was in reality flowing onward. Changes in the relative
positions of easily recognized points on the glacier and on the distant
shore were noticed during various visits, but instrumental measurements
of the rate of motion of various prominent pinnacles made by my assistant
and myself failed to give satisfactory results.

When exploration shall be extended into the mountains clustering
alxjut Mount Logan and extending northward from Mount St. Elias, the
Seward glacier will furnish the most promising highway of travel. The

I-

i '

Glaciehs of Nobth Amkuha.

Plate 16.

Fig. a. — surface OF SEWARD GJ.ACIER, ALASKA.

Tlie suiitmit of Mount St. E •<«» is seen in the Uistance, beyonil the hills bordering the glacier.

(l)riiwn from a Photograph.)

■ r

Fig. B. — DAVIDSON GLACIER. LYNN CANAL, ALASKA.

GLACIKUS OF ALASKA.

101

snow fields along the margins of the glacier where its surface is most
broken afford easy lines of march, and the ice falls can be })assed without
serious ditliculty by scaling the adjacent cliffs. When once above the
upper fall the way is clear, and a broad, snow-covered surface affords a
direct route to the immediate base of Mount Logan. In making this
journey the explorer should pass around the southern end of the Hit(di-
cock range and gain the Seward glacier just above the lower fall. When
that point is reached the way ahead is well defined. By means of snow
shoes and sleds drawn b}' dogs, an advance can be made for perhaps a hun-
dred miles into the interior. By descending a glacier on the northern
side of the mountains some stream could be reached which would c:irry the
explorer again to the coast. The clor;^ of the winter season would i)rol>
ably be the best for this attractive journey, as the crevasses would then
be deeply buried, and the rivers of the interior could be reached in vime
to descend them during the short summer.

Although Seward glacier is the largest ice stream yet discovered in
Alaska, it does not differ materially from many other's of the same type
now known to exist in that region. It is the only glacier in the neigh-
borhood of Mount St. Elias, however, which, so far as known, heads far
back in the mountain and flows through a low-grade pass to the sea. The
Hubbard glacier may have this characteristic, but as its gathering-ground
has never been seen, its relation to the mountain cannot be definitelj'^
determined. The character of the surface of the Seward glacier is shown
on Fig. A, Plate 16 ; the summit of the upturned mountain-block
forming Mount St. Elias is seen beyond the hills forming the bank
of the glacier.

The next large ice stream to the west of the Seward glacier is the Agassiz
glacier, which drains the snow fields on the south side of the Augusta
range and the eastern slope of Mount St. Elias. To the west of Mount
St. Elias rises Guyot glacier, another of the great tributaries that unite to
form the Malaspina ice sheet, the type of piedmont glaciers.

Glaciers of Lynn Canal.

It has been the writer's good fortune to make three trips through
Lynn canal, each of which furnished many independent observations on
the glaciers diveraifying its shores. The first of these journeys was made
in a canoe with a single Indian, while returning from an expedition up
the Yukon river, an account of which has been published in the Bulletin

102

OLACIEUS OF NOUTH AMEUICA.

of the Geological Society of America.^ The second and third journeys
were made on steamei-s and were much less satisfactory than the first.

Taya Inlet. — Lynn canal divides near its head into two arms, known
as Taya and Chilkat inlets. The first leads toward Chilhoot pass an<l
the second toward Chilkat pass. Each of these arms, like the main
trunk of Lynn canal, is bordered by high mountains, and receives many
swift streams issuing from caves at the lower extremities of alpine
glaciers. The larger glaciei-s drain broad neve fields which whiten the
higher portions of the mountains throughout the year. The smaller ones
have their sources in sheltered amphitheatres and cirques, but at times
originate in snow fields that rest on the mountain side, and are so promi-
nent that when seen in profile, they give a convex outline to the sides of
the peaks about which they cluster.

From a mountain top about 3000 foet high, on the west side of Taya
inlet, I obtained an extensive and most instructiv^e view of the rugged
mountains in which the blue tranquil waters of the great canal are em-
bosomed. From one stati )n I counted nearly forty glaciers, and a change
in position of half a mile brought several others into view which before
were concealed by rugged crags and snow-covered slopes near at hand.
The outlines of vast amphitheatres in the mountain tops could be traced hy
lines of pinnacles and towering, frost-riven crags forming their rims, but
the basins within were so deeply filled with snow and ice that one could
walk across them with ease. Many of the views of the mountains enclos-
ing Lynn canal, obtained from the decks of steamers, are truly magnifi-
cent, but fail to give such a comprehensive idea of the entire plan of the
hundreds of snow-clad peaks, and of the deep valleys separating them, as
the broad panoramas which reward the climber who reaches some of the
less aspiring summits. Added to the sublime picture of snowy ranges
and winding waterways obtained from such a station are wonderful cloud
effects, to be seen especiall}'^ when a storm gives way to clear skies and the;
last remnant of the vapory hosts that previously enshrouded the ranges
still cling to the more lofty summits.

Davidson Glacier. — The finest glacier on Lynn canal, named in
honor of Prof. George Davidson, of the U. S. Coast and Geodetic Survey,
has its source in the rugged mountains between Lynn canal and Glacier
bay, and flows froia the same general n^ve fields that supply some of the
principal tributaries of Muir glacier. A photograph of its expanded ex-

1 Vol. 1, 1890, pp. 99-162.

GLACIEI'.S OF ALASKA.

108

tremity, as seen from a passing vessel, is reproduced in Fig. H, Plate 1<>.
It finds its way east'vard through a deep, high-grade gorge Injtween lofty
peaks, and reaches within a few score feet of sea level, hut does not enter
the watera of the canal so as to form a title-water glacier. Moraines left
hy the glacier in its retreat, and alluvial material brought out from it by
swift, heavily laden streams, have l)een deposited about the margin of the
ice foot so as to form an encircling girdle now covered on its outer margin
with a dense spruce forest. On passing from the Ixiach through the forest
for a distance of about a mile, one comes to a barren, desolate tract of
boulders and gravel of fresh appearance, and evidently but recently
abandoned by the glacier. The hirren area is perhaps half a mile broad,
and separates the extremity of the foot of the glacier throughf)ut the entire
periphery of its expanded terminus from the encircling forest. From
archways in the ice there issue swift, roaring streams of muddy water,
much too strong and too deep for one to w.ade. These streams are heavily
loaded, and at once b^gin to deposit their burdens and to build up their
channels, so that their courses are unstable and new distributaries ar; formed
from time to time. Standing by the side of one of the streams as it issues
from its icy cavern, one may hear the clash of the boulders that are swept
along at the bottom of the turbid waters. The localities at which the
streams emerge from the ice are changed from time to time, so that the
entire area bordering the ice foot is torrent-swept and covered with
stream-borne deposits.

The ice at the lower extremity of Davidson glacier has a crystalline
appearance, much like coarsely crystallized dolomite. The banded struc-
ture generally so characteristic of glacial 'ce- is not apparent in the ex-
posed surface*. On climbing the rough crags of ice forming the immediate
foot of the glacier one finds stones and dirt scattered over its surface, but
a definite arrangement of the superficial debris in medial aid lateral mo-
raines is not apparent in a near view. From a distance, however, as from
the decks of passing vessels, well-characterized medial bands looking like
roadways can be easily recognized, as well as broad, dirt-covered areas,
answering to lateral moraines, at the bases of the enclosing cliffs.

During my canoe trip down Lynn canal in 1889, I was storm-lx)und
for three days at Davidson glacier, and sought refuge in the somljre, moss-
covered forest about its foot. One cannot fully appreciate the varied
beauties of the dense forests of Alaska until he has actually lived in their
depths and witnessed the many changes that the primeval wilderness pre-
sents during storms and sunshine. The trees are large and rugged, and

104

GLACIERS OF NORTH AMERICA.

frequently clothed, even to the ends of their topmost briiiiehes, with dense
oouts of Hhiij,'^'y nioHH. Aged trunks long since dciid and stripped of their
foliage, but still standing, assume strange, weird shapes, due to the thick
masses of mosses, lichens, ajul fungi that make their homes upon them.
Mosse!? and lichens cover the grouiul as with a dense mat a foot or more
thick, into which one sinks knee-deep at every step as if walking over a
bed of wet sponges. The trunks of fallen sachems of the fonssts an;
buried from sight by a living mound of green and brown, most artistically
decorated with llowers and ferns. Every rod that one advances into the
moist and fre(piently mist-tilled forests reveals new beauties, and fascinates
the fancy with harmonies of form and color not exceeded by those of the
moss-draped cy[)ress and live-oak forests of Floriuu.

Along the shores of Lyini canal eastward from Davidson glacier, there
are other ice streams that drain the shining snow fields on the mountains
and add variet}' and beauty to the splendid scenery of that justly famed
arm of the sea ; but none of them reach tide water. The extremities of
the larger glaciers are hidden behind fringes of forests growing on the
deposits laid down during their slow retreat. To an observer on passing
vessels, the steep, broken surfaces of the ice streams, as they descend pre-
cipitous slopes, may k^e seen above the green of the forests into whir \ey
seen] to plunge. When the summits of the mountains are enshroi in

mis* the precipices of ice appear like frozen cataracts descending from the
clouds. The glaciers of Lynn canal that rank next to Davidson glacier in
size and beauty are the Auk, Eagle, Lemon creek, and Juneau. These
are all on the northeastern shore, and are better known than those on
the opposite coast because of their proximity to the beach. There are,
besides, hundreds of nameless glaciers that would well repay individual
study, of which glimpses may be had by those who pass in a day.

Glaciers of the Interior of Alaska.

In traversing the deep valleys leading from the head of Lynn canal to
Chilkoot and Chilkat passes, one sees small glaciers on the adjacent
mountains. After passing the divide between the waters flowing directly
to the Pacific and those tributary to the rivers of the interior, other
similar glaciers occur which descend the northern slope of the mountains.
The timber line in the interior is far below the limit reached by the
glaciers, and the intervening area is barren and rugged, and strewn with
debris left by former ice streams. In the clefts between the more lofty

CJLAriKKS OP ALA8KA.

106

summits rising above tho barren area, there are tongnes of ico that (U'seend
from snow fields, tilling elevated valleys and amphitheatres alM)ut the
crests of tho mountains. These glaciers all of the alpine type, are
usually of comparatively small size, and are the sources of many swift
streams of turbid water. Their extremities are seldom lower than 8000
or 4000 feet above sea level.

The general features of tlio region draining northward in tho vicinity
of Lynn canal are Iwlieved to be characteristic of an extended l)elt of im-
perfectly explored country along the iidand .slope of the mountains
bordering the coast. Hohl explorations nuido to tho westward of Chilkat
pass, bv E. J. Glave in 1890, and again in 1801, show that in the region
(Inuned by Also k river — a wild, imi)etu()us stream th)wing through the
mountains bordering the coast — and by numerous tributaries of the
Yukon, there are many ali)ine glaciers of the same general character as
those already referred to at the head of Chilkat pa«s.

Our knowledge of the glaciers draining to the interior was mucih ex-
tended in the summer of 1891 by important explorations made by Dr. C.
Willard Hayes ^ in com[)auy with Lieut. Frederick Schwatka. This ex-
pedition ascended Taku inlet, and after lossing a low divide reached the
head watera of the Yukon, and descended that stream in boats to Selkirk
house. Thence an overland journey was made westward to Copper river,
and an extended region explored on the northern flanks of the mountains
culminating in Mount Logan and Mount St. Elias. On gaining Copper
river the expedition descended that stream to the coast, and confirmed the
report of Lieut. H. T. Allen ^ in reference to the presence of glaciers near
the sea. The principal glaciera examined by Hayes lie at a distance of
50 to 80 miles to the north and northwest of Mount St Elias, and are
described by him as follows in the paper just cited :

"Three large glaciei-s flow into the White River basin west of the
Alaskan boundary; and numerous streams, crossed while following the
southern bank of the upper White river, rise in small glaciers which do
not descend to the level of the valley.

" The largest glacier known to discharge wholly in the Yukon basin is
one which lies approximately on the 14l8t meridan, called the Klutlan,
from the native name of the river to which it gives rise. Its source is in

* " An Expedition to the Yukon District," in National Geographic Magazine, vol. 4, 1892,
pp. 117-162.

'^ "Report of an Expedition to the Copper, Tanana, and Koyukuk Rivers, Alaska,"
Washington, 1887, pp. 37-43.

106

GLACIERS OF NORTH AMERICA.

the great snow fields between Mount St. Elias and the high peaks on the
northern border of the range called Nat-azh-at by the natives. It extends
several miles beyond the foot of the range, though it is rapidly recedinj,'
at the present time, and. is between four and five miles broad where it
enters the valley. The stagnant ice in front of the retreating glacier is
buried under a great accumulation of morainal material continuous with
the terminal moraine, sc that it is impossible to determine the exact limits
of the ice. The heavy mantle of vegetation which covers the terminal
moraine continues a mile or more beyond the outer edge of the ice, be-
coming gradually less abundant as the active portion of the glacier is
approached.

" The moraine in front of the Klutlan is the largest accumulated by
any of the interior glaciers. It is composed very largely of the white
volcanic tufa already described, but with this are mingled many angular
fragments of amygdaloid lava and a few of granite and gneiss. Much of
the moraine has been removed by streams flowing from the glacier, but
remnant.o 200 feet or more in thickness extend nearly across to the high-
land north of the valley.

" The second of the White River glaciers is about midway between the
Klutlan and Scolai pass. It is much smaller than the Klutlan and does
not push out into the valley, but its front forms a wall of ice someihiiirj
over a mile in length from side to side of the narrow valley in which it lies.

" The third and largest of the intsrior glaciers flows from the high moun-
tains northwest of Mount St. Elias down into Scolai pass, and from the
divide sends a lobe of ice toward White river and a smaller one toward
Copper River basin. This -vas named in honor of Mr. I. C. Russell. The
northern or White River lobe of Russell glacier is buried under a heavy
accumulation of moraine bearing some vegetation, while the southern lobe
is almost wholly free from morainal material, and the exposed ice has
melted down to the smooth convex surface and feather edge characteristic
of stagnant ice at the front of a retreating glacier."

Taken altoj^jther, the ice flowing northward from the St. Elias moun-
tains is insignificant in amount when compared with the vast frozen flocid
that pours down through every valley, cailon, and ravine on the southern
slope of the same uplift. The Seward glacier alone probably contains a
greater volume of ice than all the glaciers flowing into the White River
basin combined.

Space will not permit me to quote more fully from Dr. Hayes' instructive
description of the glacier seen by him, or to follow his discussion of the

GLACIERS OF ALASKA.

107

climatic condition on which the distribution of the glaciers of Alaska
dejjends. His exp'.orations defined the northern limit of the present ice
drainage and furnished additional information concerning the extent
inkT.d of the glaciers of the same region in former times.

Absence of Glaciers in Central and Northern Alaska.

In the interior of Alaska and of the adjacent portion of Canada, there
are many mountains that reach elevations of at least four or five thousand
feet above the sea, but are bare of snow during the summer, and no glaciers
are known to exist upon them. This fact is the more striking for the
reason that several of the peaks referred to are near, and some of them
even north of the Arctic circle, and might be supposed to afford favorable
conditions for ice accumulation. A good illustration is thus furnished of
the conclusion long since reached, that the existence of perennial ice does
not necessarily depend upon latitude. The snow line when traced from
the most southerly peak in California that is snow-capped in summer,
northward along the Cordilleras, becomes lower and lower, until at the
base 01 Mount St. Elias it is only 2500 feet above the sea. North of the
St. Elias mountain belt, however, it rises abruptly, and so far as known xa
not reached by any elevations in the interior.

The reason for the apparent anomaly in the distribution of the glaciers
of Alaska is to be found mainly in the direction of the currents of the
Pacific and in the topography of the land. A warm ocean current,
known as the Japan current, corresponding in many ways with the Gulf
stream, impinges on the southern shore of Alaska and greatly modifies
the condition of the atmosphere. The warm, humid winds from the south,
in passing over the mountains near the coast, part with a large share of
their moisture and descend to the lower regions to the north as com-
paratively dry winds. The snowfall on the mountains adjacent to the
coast is excessive, while in the interior it is light. At elevations ex-
ceeding 8000 or 10,000 feet on the mountains near the sea every stcrm
throughout the year is accompanied with snow, and above 13,000 feet,
it is safe to say that rain never falls. In the interior, however, not only"
is a snowstorm in summer unknown, but rain seldom falls duriiig that,
^season. In winter the prevailing air currents of the interior are from,
the fix)zen sea to the northward, and are in general dry winds, for thft
reason that they travel from cold to warmer regions and tend to absorb
rather than to precipitate moisture. The mean annual temperature, and

108

GLACIERS OF NOliTH AMERICA.

still more markedly the mean winter temperature of the interior, is far
below what ii is at corresponding elevations on the coast, but. for reasons
already stated, this is not necessarily favorable to the accumulation of
perennial snow.

The glaciera of Alaska illustrate the well-known fact that the most
favorable, conditions for ice accumulation are found where a region of
condensation is adjacent to a region of active evaporation.

The influence of climatic and topographic conditions on the existence
of glaciei-s, just referred to, is again strikingly shown in the far northwest
by the records of former periods of maximum ice extension. During the
glacial period the ice fields adjacent to the Pacific Avere more extensive
than at present, but were confined to the same general region. The
glaciers that flowed northward in the vicinity of Mount St. Elias reached
only about 100 miles inland. All of the central and northern portions
of Alaska were unglaciated.

Glaciers of the Alaskan Peninsula and the Aleutian Islands.

Glaciers of the alpine type similar to those on the shores of Lynn
canal are known to exist in the mountain-enclosed valleys on the border of
Cook's inlet, and, in diminishing numbers and decreasing size, from there
westward on the Alaskan peninsula and on some of the more rugged of
the Aleutian islands. The positions of a few small glaciers on the
borders of Cook's inlet are shown on the charts published by the U. S.
Coast and Geodetic Survey, but no description of them has ever been
published. The verbal reports of traders and hunters who have visited
that region indicate that the snow fields crowning the mountains are ex-
tensive and that the glaciei-s flowing from them are well worthy of con-
sideration. The snow line appears to have an elevation of some three or
four thousand feet, and the glaciei's are mostly individual tongues of ice
descending to within a few hundred feet of the sea. None of them now
reach tide water.

The most extensive of the isolated snow fields on the Aleutian islands
yet reported cluster about the summit of Mount Makushin, the highest
peak on Iluliuk island. A view of that imposing peak rising white and
shining above a most rugged setting of lesser mountains, obtained by the
writer from a commanding summit on the eastern portion of the same
island, showed that the glaciers on its sides are sniJill and similar in many
ways to those of the High Sierra. Their lower limit appeai-s to be about

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GLACIKUS OF ALASKA.

109

4500 feet above the sea^ but the distance rendered it impossible to deter-
mine special characteristics. Some of the volcanic piles on the Aleutian
islands to the west of Ilulink are higher than Mount Makushin, ^.nd are
known to be snow-covered in summer ; but no definite information in
reference to the presence of glaciers on them is available. It is to be ex-
pected that the great Cordilleran glacier belt, when traced westward from
peak to peak on the Aleutian islands, will rise higher and higher, and that
the glacier will at the same time diminish in size, until at last the topo-
grftphic and climatic conditions will preclude their existence. Where the
extreme western tip of the crescent formed by the Cordilleran glacier belt
actually terminates remains to be determined.

Piedmont Glaciers.

Some account has already been given of the alpine glaciers on the
southern slope of the mountains that culminate in Mount Logan and
Mount St. Elias. Many of these ice streams descend onto a low plain
intervening between the mountains and the sea, and there expand and
unite one with another, so as to form vast lake-like bodies of ice to which
tlie term piedmont glaciers has been applied. Two broad ice sheets of
this nature, named in honor of the distinguished navigators Malaspina
and Bering respectively, are now known, but only the former has been
visited. Bering glacier has been seen from vessels passing along the coast
to the westward of Mount St. Elias, but vo explorer has as yet set foot
upon it.

Malaspina Glacier.

(A sketch map of Malaspina glacier forms Plate 17.)

Area. — The Malaspina glacier, as indicated on Plate 17, extends with
unbroken continuity from Yakutat bay 70 miles westward, and ha^ an
average breadth of between 20 and 25 miles. Its area is approximately
1500 square miles, or intermediate in extent between the area of the
state of Rhode Island and the area of the state of Delaware.

It is a vast, nearly horizontal plateau of ice. The general elevation of
its surface at a distance of five or six miles from its outer border is about
1500 feet. The central portion is free from moraines or dirt of any kind,
but is rough and broken by thousands and tens of thousands of crevasses.
Its surface, when not concealed by moraines, is broadly undulating, and
recalls the appearance of the rolling prairie lands west of the Mississippi.

110

GLACIEHS OF NOKTH AMERICA.

From the higher swells on its surface one may see for many miles in all
directions without ohserving a single object to break the monotony of the
frozen 2)lain. So vast is the glacier that, on looking down on it from
elevations of two or three thousand feet above it^ surface, its limits aie
beyond the reach of vision.

Lobes. — The glacier consists of three principal lobes, each of which is
practically the expansion of a large tributary ice stream. The largest has
an eastward flow, toward Yakutat bay, and is supplied mainly by tlic
Seward glacier. The next lobe to the west is the expanded terminus of
the Agassiz glacier ; its current is toward the southwest. The third great
lobe lies between the Chaix and Robinson hills, and its main supply of ico
is from the Tyndall and Guyot glaciers. Its central current is southward.
The direction of flow in the several lobes explains the distribution of the
moraines about their borders.

The Seward lobe melts away before reaching Yakutat bay and ends
with a low frontal slope, but its southern margin has been eaten into by
the ocean, so as to form the Sitkagi bluffs. The Agassiz lobe is complete,
and is fringed all about its outer border by broad moraines. The Guyot
lobe pushes boldly out into the ocean, and, breaking off, forms magnificent
ice cliffs.

Characteristics of the Non-moraiiie-coverecl Surface. — On the

northern border of the glacier, but below the line of perpetual snow, where
the great plateau of ice has a gentle sIo^jc, the surface melting givi^s
origin to hundreds of rills and rivulets which course along in channels of
clear ice until they meet a crevasse or moulin and plunge down into the
body of the glacier to join the drainage beneath. On warm summer days,
when the sun is well above the horizon, the mu'-mur of streams may be
heard wherever the ice surface is inclined and not greatly broken ; but as
soon as the shadows of evening cross the ice fields, melting ceases and tlie
silence is unbroken. These streams are alwaj^s of clear, sparkling water,
and it is seldom that their channels contain debris. Where the surface of
the glacier is nearly level, and especially when broken by crevasses, sur-
face streams are absent, although the clefts in the ice are frequently filled
with water. The moulins in which the larger of the surface streams
usually disappear are well-like holes of great depth. They are seldom
straight, however, as the water in plunging into them usually strikes the
opposite side and causes it to melt away more rapidly than the adjacent

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GLACIERS OF ALASKA.

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surfaces. The water in descending is dashed from side to side ond in-
cresises their irreguhirities, A deep roar coming from the hidden chamhei-s
to which the moulins lead frequently tells that large bodies of water are
rushing along the ice caves l)eneath. In the southern portion of the
glacier, where the ice has been deeply melted, and especially where large
crevasses occur, the abandoned tunnels nmde by englacial streams are
sometimes revealed. These tunnels are frequently 10 or 15 feet high,
and occasionally one may pass through them from one depression in the
glacier to another. In «ome instances they are floored with debris, some
of which is partially rounded. As melting progresses this material is con-
centrated at the surface as a moraine.

The ice in the various portions of the glacier was observed to be
formed of alternate blue and white bands, as is the rule in glacial ice
generally. The blue bands are of compact ice, while the white bands are
composed of ice filled with air cavities. The banded structure is usually
nearly vertical, but the dip, when noticeable, is northward. Nearly
parallel with the blue and white layers, but crossing them at low angles,
there are frequently bands of hard, blue ice several hundred feet long and
two or three inches in thickness which have a secondary origin, and are
due to the freezing of waters in fissures.

The rapid melting of the surface produces many curious phenomena,
which, as explained in a previous chapter, are common to many ice bodies
below the line of perpetual snow. The long belts of stone and dirt form-
ing the moraines protect the ice beneath from the action of the sun and
air. while adjacent surfaces waste away. The result of this differential
melting is that the moraines become elevated on ridges of ice. The forms
of the ridges vary according to the amount and chamcter of the debris
resting upon them. In places they are steep and narrow, and perhaps
150 or 200 feet high. From a little distance they look like solid masses
of debris, and resemble great railroad embankments, but on closer exami-
nation they are seen to be ridges of ice, covered with a thin sheet of earth
and stones. The sides of such ridges are exceedingly difficult to climb,
owing to the looseness of the stones, which slide from beneath one's feet
and roll down the slopes. The larger boulders are the first to be dis-
lodged by the melting of the ice, and rolling down the sides of the
ridges, form a belt of coarse debris along their margins. In this way a
marked assortment of the debris in reference to size and shape frequently
takes place. In time the narrow belts of large bouldei-s become elevated in
their turn and form the crests of secondary ridges. Rocks rolling down

112

ULACIEIIS OF NOllTli AMEKICA.

the steep .slo[)e.s are luoken into finer and finer fiii(,'tnents and are reduced
in part to tlie condition of sand and clay. When the dehris is sufliciently
comminuted it is sometimes carried away hy surfac*^ streams and waslied
into crevasses and mouhns. Not all of the turbidity of the suh^dacial
streams (!an be charged to the grinding of the glacier over the rocks on
which it rests, as a limited portion of it certainly comes from the crushing
of the surface moraines during their frecjuent changes of position.

Isolated blocks of stone lying on the glacier, when of sufficient size
not to be warmed througli by the sun's heat in a singk; dny, also [jrotect
the ice beneath and retain their position as the adjacent surface melts, so
as to rest on pedestals fre(iuently several feet high. These elevated
l)locks are usually flat, angular masses, sometimes 20 feet or more in
diameter. Owing to the greater effect of the sun on the south<;rn side of
the columns whicii support them, the tables are frequently inclined south-
ward, and ultimately slide off their pedestals in that direction. No sooner
has a block fallen from its suppoi't, however, than tiic process is again
initiated, and it is again left in relief as the adjacent surface melts. Tlie
many falls which the larger blocks receive in this manner cause them to
become broken, thus illustrating another , phase of the process of comminu-
tion to which surface moraines are subjectf^d. On Malaspina glacier the
formation of glacial tables is confined to the summer season. In winter
the surface of the glacier is snow-covered and differential melting cannot be
marked. The fact that glacial tables are seldom seen just after the snows
of winter disappear suggests that winter melting takes place to some extent,
but in a different manner from what it does in the summer. Just how the
blocks are dislodged from the pedestals in winter has not been observed.

While large objects lying on the surface of the glacier are elevated on
pedestals in the manner just described, smaller ones, as is well known, and
especially those of dark color, become heated by the sun, and melting
the ice beneath, sink into it. When small stones and dirt are gathered in
depressions on the surface of the glacier, or on a large scale, when
moulins become filled with fine debris and the adjacent surface is lowered
by melting, the material thus concentrated acts as do large boulders, and
protects the ice beneath. But as the gravel rises in reference to the
adjacent surface, the outer portion rolls down from the pedestal on all
sides, and the result is that a sharp cone of ice is formed, having a sheet
of gravel and dirt over its surface. These sand cones, as they are called,
sometimes attain a height of ten or twelve feet, and form conspicuous and
cliaracteristic features of the glaciers over large areas.

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■iBHSiiAaliiSSiMaiiiki

GLACIKKS OK ALASKA.

118

The Hiirface of Maliispina glacier over many square miles, where free
from moraine, w covered with a coral-like crust, which results from the
alternate melting and frce/.ing of the surfa(!e. The crevasses in this i)or-
tion of the viust plat»'au are seldom of large si/.e, and owing to the melting
of iheir margins, are hroad at the surfacie and contract rapidly downward.
They are in fact mere gashes, sometimes 10 or 20 feet deep, and are
apparently the rcunants of larger crevasses formed in the glaciei"s which
flow down from the mountains. Deeper crevasses occur at certain locali-
ties about the border of the glacier, where the ice at the margin falls
away from the main mass ; but these are seldom conspicuous, as the ice in
the region where they occur is always heavily covered with debris and the
openings become filled with stones and boulders. The generally level
surface of the glacier and the absence of large crevasses indicate that the
ground on which it rests is comi)aratively even. Where the larger of the
tributary glaciers join it, however, ice falls occur, caused by steep descents
in the ground beneath. These falls are just at the lower limit of per-
petual snow, and are fully revealed only when melting has reached its
maximum and the snows of tlie winter have not yet begun to accumulate.

MornincH. — From any commanding station overlooking ]Malaspina
glacier, one sees that the great central area of clear, white ice is bordered
on the south by a broad, dark band formed by boulders and stones. Out-
side of this and forming a belt concentric with it is a forest-covered Jirea,
in many places four or five miles wide. The forest grows on a moraine,
which rests upon the ice of the glacier. In a general view by far the
greater part of the surface of the glacier is seen to be foraied of clear ice,
but in crossing it one comes firnt to the forest and moraine-covered border,
Avhich, owing to the great obstacles it presents to travel, impresses one as
being more extensive than it is in reality.

The moraines not only cover all of the outer border of the gkcier, but
stream off from the mountain spurs projecting into it on the north. As
indicated on the accompanying map, one of these trains starting from a
spur of the Samovar hills crosses the entire breadth of the glacier and
joins the marginal moraine on its southern border. This long train of
stones and boulders is really a highly compound medial moraine formed
at the junction of the expanded extremities of the Seward and Agassiz
glaciers.

All of the glaciers which feed the great piedmont ice sheet are above
the snow line, and the debris they carry only appears at the surface after

114

GLAClEllS OF NOKTH AMERICA.

the ice descends to the region where the annual waste is in excess of the
annual ipply. The stones and dirt previously contained in the glacier
are then concentrated at the surface, owing to the melting of the ice.
This is the history of all of the moraines on the glacier. They are formed
of the debris brought out of the mountains by the tributary alpine glaciei-s
and concentrated at the surface by reason of the melting of the ice.

Malaspiiia glacier in retreating has left irregular hillocks of coarse
debris which are now densely ^orest-covered. These deposits do not
form a continuous terminal moraine, however, but a series of irregular
ridges and hills having a somewhat common trend. They indicate a slow
general retreat without prolonged halts. The heaps of debris left as the
ice front retreated have a general parallelism with the present margin of
the glacier and are pitted with lake basins, but only their higher portions
are exposed above the general sheet of sand and gravel spread out by
streams draining the glacier.

The blocks of stone forming the moraines now resting on the ice are
of all sizes up to 20 or 30 feet in diameter, but those of large dimen-
sions are not common. The stones are rough and angular except when
composed of material like granite, which on weathering forms oval
and rounded boulders of disintegration. So far as has been observed,
very few of the stones on the glacier have polished or striated surfaces.
The material of which the moraines are composed is of many kinds, but
individual r" Iges frequently consist of fragments of the same variety
of rock, the special kind in each case depending on the source of the
thi-ead ii. the great ice current, which brought the fragments from the
mountains.

In many instances, particularly near the outer border of the ice sheet,
there are large quantities of tenacious clay, filled with angular stones,
which is so soft, especially during heavy rains, that one may sink waist
deep in the treacherous mass. Sometimes blocks* of stone a foot or
more square float on the liquid mud and lure the unwary traveler to
disaster.

On the eastern margin of the ice sheet adjacent to Yakutat bay, where
the frontal slope is low. there are broad deposits of sand and well-rounded
gravel which has been spread out over the ice. On the extreme margin
of the glacier this deposit merges with hillocks and irregular knolls of tlio
same kind of material, some of which rise a hundred feet above the nearest
exposure of ice and are clothed with dense forests. The debris is so
abundant and the ice ends in such a low slope that it is frequently im-

GLACIERS OF ALASKA.

115

possible to determine where the glacier actually terminates. The water-
worn material here referred to as resting on the glacier has been brought
out cf tunnels in the ice, as will be noticed further on.

Surface of the Fring-ingr Moraines. — A peculiar and interesting
feature of the moraine on the stagnant border of Mjilaspina glacier is
furnished by the lakelets that occur everywhere upon it. These are found
in great numbers both in the forest-covered moraine and in the outer
border of the barren moraine. They are usually rudely circular, and have
steep walls of dirty ice which slope toward the water at high angles, but
are undercut at the bottom, so that the basins in vertical cross-section
have something of an hour-glass form. The walls are frequently from 50 to
100 feet high, with a slope of 40 to 50 degrees, and sometimes are nearly
perpendicular. Near the water's edge the banks ere undercut so as to leave
a ri Ige projecting over the water. The upper edge of the walls is formed
of the sheet of debris which covers the glacier, and the melting of the ice
beneath causes this material to roll and slide down the ice slopes and
plunge into the waters below. The lakes are usually less than 100 feet
in diameter, but larger ones are by no means uncommon, several being ob-
served which were 150 or 200 yards across. Their waters are always
turbid, ovving to the mud which is carried into them by small avalanches
and by the rills that trickle from their sides. The rattle of stones falling
into iliem is frequentlj' heard while traveling over the glacier, and is
especially noticeable on warm days, when the ice is melting rapidly, but is
even more marked during heavy rains. The crater-like walls inclosing the
lakes are seldom of uniform height, but frequently rise into pinnacles.
Between the pinnacles there are occasionally low saddles, through which
in some instances the lakes overflow. Frequently there are two low
saddles nearly opposite to each other, which suggests that the lakes were
formed by the widening of crevasses. The stones and dirt which fall into
them, owing to the melting of the walls, gradually fill their bottoms. In-
stances are numerous where the waters have escaped through crevasses or
openings in the bottom of the basin, leaving an exceedingly rough depres-
sion, with a heavy deposit of debris at the bottom.

As the general surface of the glacier is lowered "by melting, the
partially filled holes gradually disappear, and their flooi*s, owing to the
deep accumulation of debris on them, which protects the ice from melting,
become elevated above the surrounding surface, in the same manner that
glacial tables are formed. The debris covering these elevations slides down

116

GLACIEltS OF NORTH AMEUICA.

li^

their sides tos melting progresses ; and finally a rugged pyramid of ice,
covered with a thin coating of debris, occupies the place of the former
lake. These pyramids frec^uently have a height of 00 or 80 feet, and arts
sometimes nearly conical in shape. They resemble "sand cones," but are
of much greater size and are sheathed with coarser debris. The sand cones

Fid. 9. — Lakelet ox Malaspixa Glaciee, Alaska.

are usually, if not always, formed and melted away during a single
season, while the debris pyramids require several seasons for their cycle
of change.

Like the lakelets to which they owe their origin, the debris pyramids
are confined to the stagnant portions of the glacier and play an important
part in the breaking up and comminution of the material forming the
marginal moraines. Owing to the sliding of the boulders and stones into
the lakelets and their subsequent fall from the sides of the pyramids, they

GLACIKHS OF ALASKA.

117

are broken and crushed, so tliat the outer portion of the glacier, where the
process has been going on longest, is covered with finer debris and contains
more clay and sand than the inner portions.

Just how the holes containing glacial lakelets originate it is difficult to
say, but their formation seems to be initiated, as already suggested, by
the melting back of the sides of crevasses. Breaks in the general sheet of
debris covering the glacier ex[)Ose the ice beneath to the action of the sun
and rain, which causes it to melt and the crevasses to broaden. The
openings become purtially filled with water, and lakelets are formed.
The waves wash the debris from the ice about the margin of the lakelets,
thus exposing it to the direct attack of the water, which melts it more
rapidly than higher portions of the slopes are melted by the sun and rain.
It is in this manner that the characteristic hour-glass form of the basins
origiirates. Tlie lakelets are confined to the outer or stagnant portion of
ihe glacier, for the reason that motion in the ice would produce crevasses
through which the water would escape. Vv here glacial lakelets occur in
great numbers it is evident that the ice must be nearly or quite stationary,
otherwise the basins could not exist for a series of years. The lakelets
and the pyramids resultinn- from them are the most characteristic features
of the outer border of the glacier. The number of each must be many
thousand. They occur not only in the outer portion of the barren mo-
raine, but also throughout the forest-covered area still nearer the outer
margin of the glacier. Large quantities of trees and bushes fall into them
with the debris that slides from their sides, and tree trunks, roots, and soil
thus become buried in the moraines.

Forests on the Moraines. — The outer and consequently older portions
of the fringing moraines art covered with vegetation, which in places, par-
ticularly near the outer margin of the belt, has all the characteristics of
old forests. It insists principally of spruce, alder, and cottonwood trees,
and a great varii v of shrubs, bushes, and ferns. In inany places the ice
beneath the denst orest is not less than a tl.ousand feet thick. The vege-
tiition is confined principally to the bordei of the Seward lobe. Near
Vahtse river the belt is five miles broad, but decreases toward the east and
is alxsent at the Sitkagi bluffs, where the glacier is being eaten away by
the sea. It is only on the stagnant borders of the ice sheet that forests
occur. Both glacial lakelets and forests on the moraines are absent where
the ice has motion. The forest-covered portion is, by estimate, l)etween
-0 and 25 square miles in area.

118

GLACIERS OF NORTH AMERICA.

Character of the Outer .^Inr^-in. — The soutliern margin of Malaspinu
glacier, between the Yahtse and Point Manl)y, is al)rn|)t, and forms a
bluff that varies in height from 140 to 300 feet or more. The bluff is
so steep in most places and is so heavily encuml)ered with fallen trees
and boulders that it is with difficulty one can climb it. Often the
trouble in ascending is increased by landslides, Avhich have piled the
superficial r.iaterial in confused heaps, and in other instances the melting
of tiie ice beneath the vegetation has left concealed pitfalls into which
one may drop without warning. The bluff formed by the margin of the
glacier, when not washed by the sea, is boldest and steepest where the
covering of vegetation is most dense. Where the covering consists of
stones and dirt without vegetation, however, the margin may still be
bold. This is illustrated between the mouth of the Yahtee and Icy cape,
where the ice is concealed beneath a general sheet of debris, but has a
bold convex margin which rises abruptly from the desolate, torrent-swept
waste at its base.

When the glacier meets the sea the ice is cut away at the water-level,
and blocks fall from above, leaving perpendicular cliffs of clear ice. At
Icy cape there is a bold headland' of this nature from which bergs are
continuall}^ falling with a thunderous roar that may be heard fully twenty
miles away. On the crest of the cliffs of clear blue ice there is a dark
band formed by the edge of the sheet of debris covering the glacier, and
showing that the moraine which blackens its surface along its outer
margin is entirely superficial. At Sitkagi bluffs the glacier is again
washed by the sea, but the base of the ice is there just above the water-
level and recession is slow. The bluffs are heavily covered with stones
and dirt, and icebergs do not form.

At the heads of the gorges in the margin of the glacier leading to the
mouths of tunnels, the dirt-covered ice forms bold cliffs which are most
precipitous at the heads of the reentrant angles. The eastern margin rt
the icf, sheet facing Yakutat bay is low, and covered to a large extent
with water-worn debris. The ridges on the glacier formed by moraines
are there at right angles to the margin of the ice, and are bare of vege-
tation. The reason for the exceptionally lo\v slope of the eastern margin
of the ice sheet seems to be that the current jn the ice is there eastward,
and the glacier is melting back without leaving a stagnant border. :

Marginal Lakes. — The water bodies here referred to are called
marflinal lakes, for the reason that they are peculiar to the margins of

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GLACIERS OF ALASKA.

119

glaciers. Where rocks border an ice field or project through it they
become heated, especially on southern exposures, and, radiating heat to
the adjacent ice, cause it to melt. A depression is thus formed along tlie
margin of the ice which becomes a line of drainage. Water flowing
through such a channel accelerates the melting of the ice, at least until
a heavy coating of debris has accumulated. When a steep mountain
spur projects into an ice field, the lines of drainage on each side converge
and frequently unite at its extremity, forming a lake, from which the
water usually escapes through a tunnel in the ice. Typical instances of
lakes of this character occur at Terrace point, at the south end of the
Hitchcock range, and again about the base of the Chaix hills.

When a stream flows along the side of a glacier a movement in tlie
ice or the sliding of stones and dirt from its surface sometimes obstructs
the drainage and causes the formation of another variety of marginal
lakes. In such instances the imprisoned waters usually rise until
they can find an outlet across the barrier, and then cut a channel
through it.

A glacier in flowing past the base of a mountain frequently obstructs
the drainage of lateral valleys, and causes lakes to form. These usually
find outlets, as in the case of lakes at the end of mountain spurs, through
a subglacial or englacial tunnel, and are filled or emptied according as
the tunnel through which the watei"s escape affords free drainage, or is
obstructed. Several examples of this variety of marginal lakes occur
on the west and south sides of the Chaix hills. They correspond in
the mode of their formation with the well-known Merjelen lake of
Switzerland.

Other variations in the manner in which glaciers obstruct drainage
might be enumerated, but those mentioned cover all of the examples thus
far observed about Malaspina glacier. The conditions which lead to the
formation of the marginal lakes are unstable, and the records which the
lakes leave in the form of terraces, deltas, etc., are consequentl} irregular.
When streams flow into one of these lakes, deltas and horizontally
stratified lake beds are formed as in ordinary water bodies ; but, as the
lakes are subject to many fluctuations, the elevations at which the records
are made are continually changing, and in instances like those about
Malaspina glacier, where the retaining ice body is constantly diminishing,
may occupy a wide vertical interval.

Drainage begins on the southeast side of Chaix hills at Moore's
nunatak, where, during the time of our visit, there were two small lakes,

1^0

GLACIERS OF NORTH AMERICA.

walled in on nearly all sides by the moraine-covered ice of Malaspinu
glacier. The water filling these basins comes principally from the high
ice fall at the north, where the glacier descends over a projecting spur
running east from Moore's nunatak. The water escaped from the first
lake across a confused mass of debris which had slid from the ice bluff
bordering the stream^ and formed a temporary dam. Below the dam the
water soon disap[)eared beneath deeply crevassed and heavily moraine-
covered ice, and came to light once more at the mouth of a tunnel nbout
a mile to the southwest. The second lake, at the time of our visit, had
almost disappeared, but its former extent was plainly marked by a barren
sand-flat, many acres in extent, and by terraces along its western border.
The lake occupied a small embayment in the hills, tlie outlet of which
had been closed by the ice flowing past it. Below the second lake the
stream flows along the base of densely wooded knolls, and has a steep,
moraine-covered bluff of ice for its left bank. About a mile below, it
turns a sharp projection of rocks and cuts deeply into its left bank, which
stands {is an overhanging bluff of dirty ice, over 100 feet high. The
stream then flows nearly due west for some three miles to Crater lake. On
its right bank is a terrace about 150 feet high, which skirts the base of
the Chaix hills, and marks the position of the stream at a former stage.
The terrace is about 100 yards broad, and above it are two other terraces
on the mountain slope, one at an elevati >*\ of 50 feet, and the other at
75 feet, above the broad terrace- The upper terraces were only observed
at one locality, and were probably due to deposits formed in a margiiud
lake at the end of a mountain spur.

The terraces left by streams flowing between a moraine-covered glacier
and a precipitous mountain slope are peculiar and readily distinguishable
from other similar topographic features. The channels become filled
principally with debris which slides down the bank of ice. This material
is angular and unassorted, but when it is brought within the reach of
flowing waters soon becomes rounded and worn. On the margin of the
channel, adjacen*" to the glacier, there is usually a heavy deposit of unas-
sorted debris, which rests partly upon the ice and forms the actual border
of the stream. When the glacier is lowered by melting, the stream
abandons its former channel and repeats the process of terrace-building at
a lower level. The material forming the terrace at the base of Chaix
hills is largely composed of blue clay filled with both angular and rounded
stones and boulders, but its elevated bqrder is almost entirely of angular
debris. The drainage from the mountain slope above the terrace is

GLACIERS OF ALASKA.

121

obstructed by the elevated border referred to, and swamps and lagoons
have formed back of it. In the material forming the terraces there are
many tree trunks, and growing upon its surface there is a forest of large
spruce trees.

At the extreme southern end of the Chaix hills the drainage from the
northeast, which we have been tracing, joins another sti'eam from the
northwest and forms Lake Castani. This lake, like the one at Terrace
point, is at the south end of a precipitous mountain ridge projecting into
the glacier, and drains through a tunnel in the ice. The stream flowing
from it is known as the Yahtse, and flows for six or eight miles beneath
the ice before emerging at its southeril margin. Large quantities of both
coaree and fine material are being carried into Lake Castani by tributary
streams, and are there deposited as deltas and lake beds. When the lake
is drained, as sometimes happens, vast quantities of this material must be
carried into the tunnel through which the waters escape.

On the west side of Chaix hills are several other marginal lakes of the
same general character as those just described. The one next northwest
of Lake Castani occupies a long, narrow valley between two outstanding
mountain ridges, and is retained by the glacier which blocks the end of
the recess thus formed. This lake was clear of ice July, 1891, and of a
dark blue color, showing that it received little drainage from the glacier.
Other lakes on the northwest side of the Chaix hills are of a similar
nature, and during my visit were heavily blocked with floating ice. On
the north side of Chaix hills there are other small water bodies occupying
embayments, and retained by the glacier which flows past their entrances.
The water from all these lakes escapes through tunnels.

The lakes to which attention has been directed are especially interest-
ing, as they illustrate one phase of deposition depending upon glaciation,
and suggest that a great ice sheet like that which formerly covered New
England very likely gave origin to marginal lakes, the records of which
should be found on steep mountain slopes.

Drainage. — The drainage of the Malaspina glacier is essentially
englacial or subglacial. There is no surface drainage excepting in a few
localities, principally on its northern border, where there is a slight sur-
ffice slope, but even in such places the streams are short and soon plunge
into a crevasse or a moulin and join the drainage beneath.

On the lower portions of the alpine glaciers, tributary to the ma' ■.. ice
sheet, there are sometimes small streams coursing along in ice channels,

122

OLACIEU8 OF NORTH AMKRICA.

but these are short-lived. On the borders of the tributary glaciers then;
are fre([uently important streams flowiupf between the iee and the adjacent
mountain slope, but when these come down to the Malaspina glacier they
flow into tunnels and are lost to view.

Along the southern margin of the glacier, between the Yahtse and
Point Manby, there are hundreds of streams which pour out of the escarp-
ment formed by the border of the glacier, or rise like great fountains from
the gravel and bouldei's accumulated at its base. All of these are brown
and heavy with sediment and overloaded with boulders and stones. The
largest and most remarkable of these springs is the one indicated on the
accompanying map as Fountain 'stream. This comes to the surface;
through a rudely circular opening, nearly 100 feet in diameter, surrounded
in part by ice. Owing to the pressure to which the waters are subjected,
they boil up violently, and are thrown into the air to the height of 12 or
15 feet, and send jets of spray several feet higher. The waters are brown
with sediment, and rush seaward with great rapidity, forming a roaring
stream fully 200 feet broad, which soon divides into many branches, and
is spreading a sheet of gravel and sand right and left into the adjacent
forest. Where Fountain stream rises ( Face of the glacier is steep and
covered with huge boulders, many of which are too large for the wateis
to move. The finer material has been waslied away, however, and a
slight recession in the face of the ice bluff has resulted. The largest
stream draining the glacier is the Yahtse. This river, as already stated,
rises in two principal branches at the base of the Chaix hills, and flowing
through a tunnel some six or eight miles long, emerges at the border of
the glacier as a swift brown flood fully 100 feet across and 15 or 20 feet
deep. The stream^ after its subglacial course, spreads out into many
branches, and is building up an alluvial fan which has invaded and buried
several hundred acres of forest.

In traversing the coast from the YahtSe to Yakutat bay, we crossed a
large number of streams which drain the ice fields of the north, some of
which were large enough to be classed as rivers. When the streams, on
flowing away from the glacier, are large, they divide into many branches,
as do the Yahtse and Fountain, and enter the sea by several mouths.
When the streams are small, however, they usually unite to form large
rivers before entering the ocean. The Yahtse and Fountain, as we have
seen, are examples of the first, while Manby and Yahna streams are
examples of the second class. Manby stream rises in hundreds of small
springs along the margin of the glacier, which flow across a desolate,

aHM

GLACIKUS OF ALASKA.

128

torrent-swept area, and unite just before reaching the ocean into one
broad, swift flood of muddy water, much too dee]) for one to wade.

On the border of the ghicier facing Yakutat Iwy, however, the <hain-
age is different. The flow of the ice is there eastward, although the
iiiargiki is probably stagnant, and instead of forming a bold, (Mintinuous
escarpment, ends irregularly and with a low frontal slope. The principal
streams on the eastern margin in 1891, were the Osar, Kame, an»l Kwik.
l"^ach of these issues from a tunnel and flows for some distance between
walls of ice. Of the three streams mentioned, the most inteicsting is the
Kame, which issues as a swift brown flood partially choked with broken
ice from the mouth of a tunnel, and flows for half a mile in an oj)en cut
between precipitous walls of dirty ice 80 to 100 feet high. I'his is the
longest open drainage channel that I have yet seen in the ice. It is about
50 feet broad where the stream rushes from the glacier, but soon widens
to several times this breadth. Its bottom is covered with rounded gravel
and sand, and along its sides are sand-flats and terraces of gravel resting
upon ice. The swift, muddy current was dotted with small bergs stranded
here and there in the center of the stream, showing that the water was
shallow. Evidently the stream has a long subglacial course, and carries
with it large quantities of stones, which are rounded as in ordinary rivers.
Gravel and sand are being rapidly deposited in the ice channel through
which it flows after emerging from its tunnel. Broad sand-flats aie being
spread out in the lakes and swamps two or three miles to the east. The
stream is some four or five miles in length, and near Yakutat bay
meanders over a barren area perhaps a mile broad. I have called it Kame
stream because of a ridge of gravel running parallel with it, which Avas
deposited during a former stage, when the waters flowed al)()ut 100 feet
higher than now and built up a long ridge of gravel on the ice which
has all the characteristics of the kames in New England. In the more
definite classification of glacial sediments now adopted, this would more
properly be called an osar.

Near the shore of Yakutat bay, the streams from the glacier spread
out in lagoons and sand-flats, where much of the finer portion of the
material they carry is deposited. Sometimes this debris is sj^read out
above the ice, and forms level terraces of fine sand and mud which Ijecome
prominent as the glacier wastes away.

Osars. — The drainage of tb^ glacier has not 'been investigated as
fully as its importance demands, but the observations already made seem

124

OLACIEKS OF NOICTII AMEIIICA.

jass.

to warrant certain conclusions in reference to deposits made within the
ghicier by suhghicial or engUuiial streams.

When the streams from tlie north reach the glacier they invariably
flow into tunnels and disappear from view. The entrances to the tunnels
are frecpiently high arches, and the streams flowing into them carry along
great cjuantities of gravel and sand. About the southern and eastern
borders of the glacier, where the streams emerge, the arches of the tunnels
are low, owing i)rinci[)ally to the accumul'Uion of debris which obstructs
their discharge. In some instances, as at tiie head of Fountain streanj,
the accumulation of debris is so great that the water rises through a
vertical shaft in order to reach the surface, and rushes upward under
great pressure. The streams flowing from the glacier bring out large
(juantities of well-rounded sand and gravel, much of which is immediately
deposited in alluvial cones. This much of the work of subglacial streams
is open to view, and enables one to infer what takes place within the
tunnels, and tr> analyze, to some extent, the processes of stream depo-
sition beneath gbaciai ic?

The streams issuing from the ice are overloaded, and besides, on
emerging, frequently receive large quantities of coarse debris from the
adjacent moraine-covered ice cliffs. The streams at once deposit the
coarser portion of their loads, thus building up their channels and obstruct-
ijig the outlets of the tunnels. The blocking of the tunnels must cause
the subglacial streams to lose force and deposit sand and gravel on the
bottom of their channels ; this causes the water to flow at higher levels,
and, coming in contact with the roofs of the tunnels, enlarges them
upwards ; this in turn gives room for additional deposits within the ice
as the alluvial cones at the extremities of the tunnels grow in height"
In this way narrow ridges of gravel and sand, having, perhaps, some
stratification due to periodic variations in the volume of the streams, may
be formed within the ice. When the glacier melts, the gravel ridges con-
tained within it will be exposed at the surface, and as the supporting walls
melt away, the gravel at the top of the ridge will tend to slide down so
as to give the deposit a pseudo-anticlinal structure. Ridges of gravel
deposited in tunnels beneath the moraine-covered portion of the ISJalaspina
glacier would have boulders dropped upon them as the ice melts, but
where the glacier is free from surface debris there would be no angular
material left upon the ridges when the ice finally disappeared. Such a
system of deposition as is sketched above would residt in the formation
of narrow, winding ridges of cross-bedded sand and gravel, corresponding.

riLArir.HH OK North Amkkk a.

P1.ATIC 21.

Fig, a. — moraine-covered BORDER OF MALASPINA GLACIER, FROM

BLOSSOM ISLAND.

(Dniwii lri>iii a I'liotonriiph.)

Fig. B. — ENTRANCE TO TUNNEL IN MALASPINA GLACIER.
CDrawn from a Photograph.)

seemi
proce;
of th€
it is e
mighl

Malas

sand,

deposi

comm

the "

portio

not be

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]\Ialas

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and d(

in this

of a ti

coarse

region

beneat

alluvia

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»nwj«wi

GLACIKUS OF ALASKA.

125

seemingly, in every way to the osars of many glaciated regions. The
process of suhglacial deposition pertains especially to stagnant ice sheets
of the Malaspina type, which are wasting away. In an advancing glacier
it is evident that the conditions would be different, and sul)glacial erosion
might take place instead of suhglacial deposition.

Alluvial Cones. — Below the outlets of the tunnels through which
Malaspina glacier is drained, there are immense deposits of boulders, gravel,
sand, and mud which have the form of segments of low cones. These
deposits are of the nature of the "alluvial cones" or "alluvial fans" so
common at the bases of mountains in arid regions, and are also related to
the "cones of dejection," deposited by torrents, and to the subaerial
portion of the deltas of swift strcrms. As deposits of this nature have
not been satisfactorily classified, I shall, for the present, call them " alluvial
cones."

As stated in speaking of osars, the streams issuing from tunnels in
Malaspina glacier at once begin to deposit. The larger bouldera and
stones are first dropped, while gravel, sand, and silt are carried farther
and deposited in the order of their coarseness. The deposits originating
in this way have a conical form, the apex of each cone being at the mouth
of a tunnel. As the apexes of the cones are raised by the deposition of
coarse material, their peripheries expand in all directions, and, as the
region is densely forest-covered, great quantities of trees beoorae buried
beneath them. As the ice at the head of an alluvial cone recedes, the
alluvial deposit follows it by deposition on the .ip-stream side. The growth
of the alluvial cones will continue so long as the glacier continues to
retreat, or until the streams vrhich flow over them have their suhglacial
courses changed. The material of the alluvial cones is as heterogeneous
as the material forming the moraines on the border of the glacier about
which they form, but the greater, and practically the entire, accumulation
is more or less rounded and waterworn. Cross stratification characterizes
the deposits throughout, and on the surface of many of the cones and
probably in their interior, also, there are large quantities of broken tree
tiimks and branches. The coarse deposits first laid down on a growing
alhivial cone are buried beneath later deposits of finer material in such a
way that a somewhat regular stratification may result. A deep section
<it' one of these deposits should show a gradual change from fine material
at the top to coarse stones and subangular ^ouldei-s at the bottom. Their
outer borders are of fine sand and mud, and when the distance of the

I UViipi W Wi|

120

GLACIERS OF NORTH AMERICA.

ocean is sufficient, the streams flowing from them deposit large quantities
of silt on their flood plains. The very finest of the glacial mud is
delivered to the ocean and discolors its water for many miles from land.
The formation of alluvial cones about the border of a stagnant kc,
sheet and the deposition of ridges of gravel within it, have an intimati;
connection, and are, in fact, but phases of a single process. The growth
of an alluvial cone tends to obstruct the mouth of the tunnel through
which its feeding stream dischar[;es ; this causes the stream to deposit
within the tunnel ; this again raises the stream and allows it to build its
alluvial cone still higher. In the case of Malasi)ina glacier, where this
process ^as been observed, the ice sheet is stagnant, at least on its border,
and is retreating. The ground on which it rests is low, but is thought to
be slightly higher en the southern margin of the glacier than under its
central portion. The best development of alluvial cones and osars would
be expected in a stac,'nant ice sheet resting on a gently inclined surface,
with high lands on tJie upper border from whi^;h abundant debris could
be derived. These ideal conditions are nearly reached in the example
described.

Glacial aiitl Ocean Records. — Much has been written concerning
the clifiracter of the deposits made ^)y glaciers wdcu they meet the ocean,
but so far as can be judged from the conditions observed about the bordeis
of Malaspina ice sheet, the sea is mucii more powerful than the ice.
Where the two unite their action, the sta leaves the more conspicuous
records. The waters are active and aggressive, while the glacier is
passive. Where the glacier enters the ocean its records are at once
modified and to a great extent obliterated. The presence of large boulders
in marine sediments or in gravels and sands along the coast 's about all
the evidence of glacial uction that can be expected under the conditions
referred to. Where the swift streams from the Malaspina glacier enter
the ocean, the supremacy of the waves, tided, and currents is even more
marked. The streams' are immediately turned aside by the accumulation
of sandbars across their mouths, and notliing of the nature of stream-worn
channels beneath the level of the ocean can exist. All of the deposits
along the immediate shore between the Yahtse and Yakutat bay have the
characteristic topogrtiphic features resulting from the action of waves and
currents, and do not even suggest the proximity of a great glacier.

Recent Advance. — On the eastern margin of Malaspina glacier,
about four miles north of Point Manby, there is a locality where the ice

GLACIEUS OF ALASKA.

127

lias recently advanced into the dense forest and cut scores of great spruce
trees short off and piled them in confused heaps. After this advance the
ice retreated, leaving the surface strewn with irregular heajjs of houlders
and stones, and enclosing many basnis, which, at the time of our visit, were
full of water to the brim. The glacier, during its advance, ploughed up
a ridge of blue clay in front of it, thus revealing, in a very satisfactory
manner, the character of the strata on which it rests. The clay is thickly
charged with sea-shells of living species, proving that the glacier, during
its former great advance, probably extended to the ocean, and that a rise
of the land lias subsecjuentlj' occurred. This is in harmony with many
other observations which show that the coast adjacent to Malaspina
glacier is now rising. The blue color of the subglacial strata is in marked
c<:ntrast with the browns and yellows of the moraines left on its surface
hy the retreati'ig ice, which, in common with the fringing moraines still
resting on the glacier, show considerable weatheriu'^, Among the shells
collected in the subglacial clay, Dr. W. H. Dall has identified the

following : '

Cardium aronlaniUcnm. Gronl.
Cardium islandieum, L.
Kennerlia (/randis^ Dall.
Leda fossa. Baird.
Macoma sahulosa, Spengler.

Similar shells, all of living species, were previously found at an
elevation of 5000 feet on the crest of a fault scarp at Pinnacle pass,
pillowing that recent elevations of land, much greater than the one
recorded in the marine clay just noticed, have taken place. In fact there
iue several indications that the coast in the vicinity has been rising, and
that the same process is still continuing.

Subsoil Ice.i

On several occasions while traveling in central and northern Alaska,
I fonnd, by removing a few inches of the moss which generally covers
the ground, that the subsoil was solidly frozen. This occurrence was
especially striking on summer days Avhen the (empj^ratnre of the air in
the shade was frequently l)etween 90° aiul 100° of the Fahrenheit scale.

' Observations on tlie subsoil ioe of Alaska by the present vvriler, logether with referencea
to a number of previously publislied papers oii the same subject, may be found in tlie Bulletl'i
of the Geological Society of America, vol. 1, pp. 125-133.

128

GLACIERS OF NORTH AMERICA.

Along the Yukon, from its mouth to near its source, one may fre-
quently see strata of clear ice, or more frequently of black, dirt-'AiaincA
ice and frozen gravel several feet thick, in the freshly cut l/df)ks <A th
stream. In general, throughout the low-lying portions of central AVdHiut
subsoil ice exists at a depth of but a few inches beneath the ioyesirfA/z-rfd
surface. The maximum thickness of this permanently frozen layer ig jv/
known, but in a few instances of which I have authentic intormati<»ii, M
has been penetrated to a depth of 25 feet without reaching the bottofti.

Explorations conducted by Lieut. J. C Cantwell,^ of the C H.
Revenue Marine service, along the Kowak river, which flows itt*/)
Kotzebue sound, about 260 miles north of the mouth of the Yukon, and
just within the Arctic circle, have shown that a layer of subsoil ice from
100 to 200 feet thick has there been cut into by the streams so as to
leave steep bluffs of solid ice along their borders. The ice covers the
land like a stratum of rock, and has been dissected by stream erosion in
much the same manner that river channels are corraded in other regions.
Above he ice there is a thin covering of rich black soil supporting a
growth of mosses, grasses, and trees. Instructive illustrations of the Kowak
river flowing between precipitous, caflon-like walls of ice are presented in
the report just referred to.

One of the most striking exposures of subsoil ice in Alaska, and one that
has been described by many travelers, exists on the shore of Eschscholtz
bay at the head of Kotzebue sound. The ice there forms a bold bluff.
and has been estimated to be from 150 to 300 feet thick. It is covered
with rich humus, on Avhich grasses grow luxuriantly. In this instance, as
in several other similar examples that are known, the ice contains the
bones of the mammoth and other large animals that are now extinct.
The soil which accumulates as the ice melts, owing to the concentration
at the surface of the impurities it contains, has a strong odor of decayiniT
animal matter. We are thus assured that the subsoil ice, in certain
instances, and probably over extensive areas, was formed at a time so
remote that the animals then inhabiting the country in great numbers
have sine'* become exLlnct.

The ice in the banks of the lower Yukon, and in the vicinity of
Kot'-ebue sound, is a part of a vast slieet of frozen subsoil that underlies
large portions of the low, marshy vegion fringing the shores of BeriiiLj

^ 'A Narrative Accou;it of the Exploration ot the Kowak River, Alaska," in Report "f
the Cruise of the Revenue Marine Steamer Cawnn, hi the Arctic Ore > -" ■ -^ar 18S j,
by Capt M. A. Healy, Ireasury Department, Wa&hhigton. D.C, i'.*""

..Ltt^>lV^

GLAOIEKS OF ALASKA.

129

4«A and the Arctic ocean. This tundra, as it is termed, covers many
ffj/msands of square miles. It is bright with mosses and a profusion of
low, flowering plants during the short Arctic summer, but beneath its
iiixuriant carpet of verdure the ground is always frozen.

Still juore extensive tundras cover the low lands forming the Arctic
^40^4^ *>i Asia, and have there been penetrated to a depth of nearly 400
(^M Wl^mut reaching the bottom of the subsoil ice. It is in this deposit
tl*»t tlie complete carcasses of the mammoth and of the woolly rhinoceros
re found from time to time. The fossil ivory gathered along the banks
of the rivers in this 4rctic region is said to be even more important as an
article of commerce than the elephant tusks obtained in the jungles of
Africa.

It is not probable that all of the subsoil ice of northern regions has
])een formed in one way. Along the flood plains and on the deltas of
rivers where layers of clear ice are interbedded with sheets of frozen
gravel and vegetable matter, as is frequently the case, it seems evident
that the growth of the deposit is due, in some instances, to the flooding
of previously frozen layers, and the freezing and subsequent burial of the
sediment thus added to their surfaces. When spring freshets spread out
sheets of debris over the flood plain of a river, as frequently happens when
streams in high latitudes flow northward, the previously frozen soil and
the ice of ponds and swamps may be buried and indefinitely preserved.
During the succeeding winter the surface layer thus added would itself
become frozen, and perhaps in its turn become buried beneath later
deposits of the same character at intervals of one or more years.

On the tundras the luxuriant growth of vegetation that start'^ into life
as soon as the winter's snow has disappeared, and grows rapidly during
the long, hot summer days, dies below and partially decays, but becomes
frozen and has its complete destruction arrested, while the dense mat of
roots and stems above continues to thrive. In this way an accumulation of
partially decayed vegetable matter is formed, which increases in thickness
from year to year by additions to its surface. The process is similar to
that by which peat bogs are formed in temperate latitudes, except that
the partially decomposed vegetation becomes solidly frozen. It is in
reality an example of cold storage on a grand scale. This slow accumu-
lation in northern regions of vegetable matter, together with the bones
and even complete carcasses of animals, is truly a Avonderful process.
Under existing climatic conditions there does not seem to be any limit
to the depth such deposits may ;\ttair.. The amount of carbonaceous

IP'PliHHSii,"-

■ ^

^^n '1

130

GLACIERS OF NOUTH AMERICA.

material already accumulated in the tundras of America and Asia must
ecjual that of the most expensive coal field known. i view of these
facts it does not seem an unreasonable suggestion thai '>me coal seams
might have originated from the vegetable matter accumulated in ancient
tundras.

There is still another process by which frozen subsoil may be formed
in higli latitudes : this is, the effects of the cold duiing the long winters
are not counteracted by the heat during the short summers. Under the
conditions now prevailing in northern Alaska, where the mean annual tem-
perature is below 32° Fahrenheit, the frozen layer tends to increase in thick-
ness from year to year just as the depth of frozen soil in more temperate
latitudes may increase from month to month during the winter season.
During the sliort northern summers, especially where the gro\ind is moss-
covered, melting only extends a few inches below the surface.

Computations made by Prof. R. S. Woodward ^ have shown that the
freezing of even the deepest ice stratum yet discovered in Ai'ctic regions
might have resulted in the course of a few thousand years from a mean
amrual temperature no lower than that prevailing in northern Alaska at
the present time.

The subsoil ice described above lacki^ most of the characteristics of
glaciers aaad should not he included among them. It is so closely analo-
gous, however, to the condition reached by continental and i>iedmont
glaciers when they iwecome stagimiit and are wasting away, that the mode
of its formation i-eiris to be understood in order that the two may not be
confounded- The liniiitic conditi'v .s admitting of the accumulation of
subsoil ^ simiar. uud probaLly identical, to those which initiate

glacial p'u it MCT. Im times immediately ]ireceding the formation of conti-
nental <]^u.'iers, it ie p«i<«ible that subsoil ice like ♦^hat of the tundras may
be formed over extensive regions before they become covered by a flowing
ice sheet. In soeli an instance the frozen subsoil might become a part of a
continental giaeier when covered by the advancing ice. During the
amelioration of climate following an ice invasion, the tundra phase might
again return, so that a glacial p<n"iod would l)e lx«th preceded and followed
by a time when the mean annual temperature would tavor the existence
of deeply frozen subsoil, and, at the same tmie, adnut of the grow th of
luxuriant forests.

1 Geological Society of America, Buleti'i vol. 1, pp. 131, 132.

CHAPTER VII.

^mm.

GLACIERS IN THE GREENLAND REGION.

Grlnncll Land. — Explorations in tlie extreme northeastern part of
North America have been carried on principally along the navigable water
ways. It is only recently that a knowledge has been gained of the vast
snow fields in which the glaciers descending to the sea have their origin.
The most instructive journeys that have been made on the islands to the
west of Baffin's bay, Davis strait, etc., were by membei-s of the Lady
Franklin Bay expedition in 1882. Gen. A. W. (Jreely, in his admiral)le
account of " Three Yeai-s of Arctic Service," describes the United States
mountains in the northern part of Grinnell land, as being buried beneath
neve snow, and apparently presenting much the >.ime appear.) nee as the
desolate region to the north of Moiuit St. Elias, described in the preceding
chapter.

The largest ice stream draining the snow lields rif (h-innell land yet
discovered, known as the Henrietta Nesmith glacier, floww south and
terminates near Lake Hazen. The most striking feature of tins great
glacier, and one that seems to l)e characteristic of many rrf the ice streams
of the far north, is the extremely i)r»*ipitous sloi)e in which it terminates.
As shown in an illustration pid)lishefl by General Greely. its exteemity i»
a nearly vertical wall of ice, perliaps 150 or 200 feet high. Tlie main
glacier is formed by the union of five ia<lependent streams, whicii pour
doAvn from an extensive ice cap to th«- north of the Garfield range and
south of the United States mountains. A tributary from tin- " ' -ins
the main glacier about four miles above its terminus, and ;t ^<-<. ymu and
third tributary comes in from the northeast about seven am^ ten miles,
respectively, inland. The main glacier is separated from the lowest tribu-
tary by a roundeH mountain s])ur, which from the statif)n occupied hj
the explorer cut off the view in that direction. In all other (juaitei's,
liowever, the view was unobstructed, and embraced aboet 18 degrees

of aZimUthr— i- _„-_--,-_-.. -,.;.-,„i.-..-,.., „:._^^^-„ , ,_.;^_._-,--:,,,_i>.,_;-^-^:„.

The description*) and sketches published by Greely seem to show that
the United States mountains are covered with a general neve field through
which the higher peaks project, and that large glaciiers, resembling most

132

GLACIERS OF NORTH AMERICA.

nearly those of the ai|)ine type, descend from the snow-covered uplands
in various directions. The ice streams flowing southward are the l)est
known, although hut hastily examined, as explorations have heen carried
nearest to the mountains in that direction.

Reports hy Lieut. J. li. Lockwood and Serg. D. L. Brainard ^ of
explorations across Griimell land from Archer fiord on the east to Greely
fiord on the west, show that the land hoth to the north and south of thti
route followed is heavily covered with snow fields and glaciere. The
region to the south, especially, is mounttiinous, and the higher peaks and
domes alone reveal their forms ahove the all-pervading snow fields. From
this elevated neve a vast glacier or series of more or less confluent
glaciers, named "Mer de Glace Agassiz," flows northward, and, hreakiiij.^
into individual ice streams, send out branches, some of which become tide-
water glaciers on reaching Greely fiord. The most remarkable feature of
the glaciers seen by Lockwood and Brainard, as in the case of the Henri-
etta Nesmith glacier, is the precipitous manner in which the ice ends.
The glaciers seem to terminate on the land as abruptly as do tide-water
glaciers in more southern latitudes on entering the sea. The long line
of ice cliffs marking the northern margin of Mer de Glace Agassiz is
termed the "Chinese Wall" in the report referred to, and, as shown in
sketches, when seen from the north present the appearance of a vast wall
of ice trending across the country in a general east and west direction,
and forming an escarpment apparently two or three hundred feet higli.
Kising beyond this wAi of ice, and seen over its crest, are the snow
fields and bald, snow-covered mountains where the great glacier has
its source.

From what is known of Grinnell land it appears that the glaciers
covering its more elevated portions are of the alpine tyj;»e, but differ from
the glaciers in the mountainous portions of more southern lands for the
reason that their gathering grounds are comparatively low, and also
because the snowfall is light and melting greatly retarded. The result is
that glaciei-s of great size are formed in regions but little elevated above
the sea, and that, from some combination of conditions not yet fully
explained, they end abruptly in precipitous escarpments.^

' Tn ""Tieport of the Proceedings of the U. S. Expedition to Lady Franklin Bay," by
A. W. Greely, Washington, 1888, vol. 1, pp. 274-206.

'•* Since this book was written, Prof. T. C. Chamberlin has made a study of some of the
glaciers of Greenland, and has suggested that the low angle of incidence of the sun's rays in
the far north may explain the peculiar manner in which the glaciers there terminate.

GLACIERS IN THE GKEENLAND llEOlON.

133

The general climatic and topographic conditions characterizing Grin-
iiell land seem to extend southward and cnd)race neighlK)ring land areas,
i)ut explorers have yet to discover the limits of the glaciei^s in that region,
and to make more critical studies of the entire glacial system of the north-
eastern corner of the continent.

^np

Greenland.

While the northern shore of Greenland remains unexplored it will he
impossible to determine the full extent of the land or of the ie3 sheet
covering it. From the most reliable data available, however, it is probable
that the land is about 1500 miles long from north to south, and 800 miles
broad in the widest portion. As estimated by Lieut. II. E. Peary, i .8
area is apiwoximately 750,000 square miles, of which fully 000,000 are ice
and snow covered.

The interior of Gregnland is reported by the few bold explorers who
have crossed it to be completely buried beneath a featureless plain of
snow. This covering has reached such a dei)th in all of the central part
that not a single mountain peak is known to break the even monotony of
its surface. The snow is highest and prcyr>ably deepest in the central area,
and descends toward the coast, thus giving the island a convex surface.
The general elevation of the central portion is from 7000 to 8000 feet,
decreasing gradually toward the coast, especially to the east and west, where
the glaciers, protruding like great tongues of ice from the central regi'^>n,
come down to the sea. The only mountain peaks that rise above the
surface of the general covering of snow are within from 50 to 75 miles of
the coast. These partially buried peaks rise like islands in the sea of
white. They are known to the inhabitants of the coast as nunataks; a
convenient name that has found a place in geological literature.

The depth of the nearly universal covering of snow and ice under
which Greenland is buried canno-t Ije told, as it is impossible to determine
ihe topography of the land beneath. The best esti nates that can be made
place its depth at several thousand feet. In the central portion, where
the covering is apparently thickest, its depth may be fully equal to the
height of the surface above the sea, or about 8000 feet.

Like the n^v^s of smaller glaciers, the surface of all the central part
of the Greenland ice sheet is composed of light granular snow. This
greatest of all n^ves in the northern hemisphere is remarkably uniform in
contour and unbroken by crevjisses and unscored by water courses in all

134

GLACIERS OF NOIITII AMERICA.

of itH central area. The ice formed Injueath the ii^'ve in the interior flows
outward iii all directions through the ])asse.s in the mountains in independ-
ent ice streams, many of which reath the ocean and form the largest tide-
water glaciers known, with the exception of those in Antarctic regions.
One of the grandest of these tongues of ice is the Humboldt glacier, whidi
flows westward ami discjiarges into Kane basin in about latitude 7U° 8U'.
The extremity of this glacier, exi)lorcd and named by Dr. Kane, forms a
wall of ice that is reported to be 40 miles long and from 'J"0 to 800 feet
high above the sea. The veritable mountains of ice thatbnnik away from
tlie partially submerged face are of astonishing dimensions, and in many
instances find their way southward through BalVm's bay to the banks of
Newfoundland, and endanger the safety of trans-Atlantic steamers.

At many localitikjs about the Ijorders of Greenland, the rough, broken
extremities of glaciei-s similar to Humboldt glacier are known to enter the
sea. The adjacent waters are crowded with bergs shed off by these tide-
water glaciers, and also with floe ice originating from the freezing of sea
water. In numerous instances the tide-water glaciers end at the heads of
deep fiords, as in tiie case of many Alaskan glaciei-s. Again, the ice
terminates on land and presents steep, broken surfaces, that are so deei)ly
gashed and so shattered into pinnacles and spires that it is imi)ossible to
cross them. When tlie topography of the high lands bordi'ring the coast
is not favorable to the formation of tongue-like glaciers in deep valleys,
the ice from the great interioi reservoir presses outwaid and terminates
in blue cliffs high up on rocky slopes, but melts before descending to the
sea. The rocks now bordering the glaciers, and in part confining them,
are in many localities rounded, smoothed, and striated, showijig that in
former times the ice inundations were much more extensive than at
present, and reached the sea on every hand. In other localities, as
recently determined by Chamberlin, the land near the west coast has
never been ice-covered. A small driftless area on the shove of Ingerfield
gulf is one of the most interesting discoveries made in Greenland in recent
years, and shows th.at the previously entertained idea that during former
periods of maximum glaciation the land was entirely ice-covered is
incorrect. -"'

The information now in hand concerning the Greenland ice sheet is
the result of combined observations of many explorers. Space will not
admit of an historical review of the slow progress that has been made in
gathering information of scientific value in the far north, but the student
who desires to follow up the subject will find the necessary references in

OLACIEUS IN THE OKEENLAND REGION.

185

the summaries of the j,'eoh)p[iejil results of northern exphuation iiulieated
in the f'>] lowing footnote.^

The rough ice met with on the borders of Greenland has been
deseril)ed by many writei-s. >(Miih of al)out latitude 70° it presents the
( haraeteristies of the lower extremities of alpine glacici-s in less remote
regions. In the northern part of the continent, however, it ends in
exceptionally ]ireci])itous : 'opes. T'le tongue (»f ice reaching seaward
between bold U[)lands on the west coast near Disco island, in latitude (11)°
^}0', is a characteristic examj)le of what may be seen at many other local-
ities on the M'ild (ireenland coast. This protrusion of the island ice is
described by Lieutenant Penry as follows :

" Wherever the ice projects down a valley in a long tonguf or stream,
the edges contract and shrink away from the warmer ro<ks on each side
having a deep cailon between, usually occupieil by a glacial stream. . . .
Higher up, along the unbroken portion of the dam [i.e. enclosing moun-
tains], where the rocks have a southern ex})osure or rise mucli above the
ice, there is apt to be a deep cailon between the ice and the rocks ; the
ice face, sometimes CO feet high, puic, pale green, and flinty.'-^ In another
place the ice face may be so striated and discoloied as to be a pi.cise
<'()unterpart of the rock opposite, looking as if torn from it by some con-
vulsion. The bottom of the cailon is almost invariably occupied by
water. . . . Still farther up, at the very crest of the dam, the ice lies
iimoothly against the rocks.

"As to the features of the interior beyond the coastlim;, the surface
of the ' ice blink ' near the margin is a succession of rounded hummocks,
steepest and highest on their landward sides, which are sometimes pre-
cipitous. Farther in these hummocks merge into long, flat swells, which
in tuin decrease in height toward the interior, until at last a flat, gently
rising plain is reached, which doubtless becomes ultimately level."

The great Humboldt glacier, alieady I'eferred to, j)resents another
example of the characteristic scenery of the Greenland coast, as is shown
by th.i following graphic description by Dr. Kane :

1 Dr. II. Rink, " Results of the Recent Danish Explorations in Greenland with Recjard
to the Inland Ice (1878-18d9)," in Edinburg G.jol. Soc. Trans., vol. 5, 1888, pp. ii80-20;i.
Dr. F. Nansen, " Firet Crossing of Creenland," vol. 1, pp. 450-610.
n. Frederick Wright, 'Ice Age in No"th America," pp. 07-01.

Warren Upham, "The Ice Sheet of Greenland," in American Geologist, vol. 8, 1804,
pp. 14 152.
__^ Jumes Geikie, "The Great Ice Age," 3d ed., 1894, pp. 42-61.

T. C. Chamberlin, in the Geological .louriial (Chicago) for 1804-1896.
^ American Geographical Society, Bullet i i, vol. 19, 1887, p. 286.

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136

GLACIEKS OF NOllTli AMEltlCA.

" The trend of this glacier is n, few degrees to the west of north. We
followed its tace eastward, edging in for the Greenland coast, about tin;
ro^ky archipelago which I have named after the Advance. From one of
these rugged islets, the nearest to the glacier which could be approached
with anything like safety, I could see another island larger and closer in
shore, already half covered by the encroaching face of the glacier, and
great masses of ice still detaching themselves and splintering as they fell
upon the poitions which protruded. Repose was not the characteristic of
this seemingly solid mass ; every feature indicated activity, eneig\ ,
movement.

" The surface seemed to follow that of the adjacent country over which
it flowed. It was undulating about the horizon, but as it descendeil
toward the sea it represented a broken plain with a general inclination of
some nine degrees, still diminishing toward the foreground. Crevtisses,
in the distance mere wrinkles, expanded as they came nearer, and were
crossed almost at right angles by long continuous lines of fracture parallel
with the face of the glacier.

" These lin^s, too, scarcely traceable in the far distance, widened as
they approached the sea, until they foimed a gigantic stairway. It seemed
as though the ice had lost its support belov und that the mass was let
down from above in a series of steps. Such an action, owing to the heat
derived from the soil, the excess of surface-drainage, and the constant
abrasion of the sea, must in reality take place. The indications of a great
propelling agenc}' seamed to bo just commencing at the time I was observ-
ing it- These split-off lines of ice were evidently in motion, pressed on
by those behind, but still widening their fissures, as if he impelling^
action was more energetic near the water, till at last they floated away in
tlie form of icebergs. Long files of these detached masses could be traced
slowly sailing off into the distance, their separation marked by dark
parallel shadows — broad and spacious avenues near the eye, but narrowed
in the perspective to mere lines. A more impressive illustration of the
forces of nature can hardly be conceived. , . .

" The frozen mass before me was similar in structure to the Alpine and
Norwegian ice growths. It would be foreign to the character of this book
to enter into the discussion which the remark suggests ; but it will be
seen by the sketch, imperfect as it is, that their face presented nearly all
the chamcteristic features of the Swiss Alps. The 'overflow,' as I ha\t'
called the viscous overlapping of the surface, was more clearly marked
than upon any Alpine glacier with which I am acquainted. When close

GL4CIE11S IN THE GREENLAND REGION.

187

to the island rocks and looking out upon the upper table of the glacier, I
was struck with the timely analogy of the batter-cake spreading itself
under the ladle of the housewife, the upper surface less affected by
friction, and rolling forward in consequence.

• '' The crevasses bore the mark of direct fracture and the more gradual
action 01 surface drainage. The extensive watershed between their con-
verging planes gave to the icy surface most of the hydrographic features
of a river system. The ice-born rivei-s which divided them were margined
occasionally with spires of discolored ice and generally lost themselvef? in
the central area of the glacier before reaching its foreground. Occasion-
ally, too, the face of the glacier was cut by vertical lines, which, as in the
Alpine growths, were evidently outlets for the surface drainage. Every-
thing was, of coui-se, bound by solid ice when I looked at it ; but the
evidence of torrentr-action was unequivocal, and Mr. Bonsall and Mr.
Morton, at their visit of the preceding year, found both cascades and
water tunnels in abundance.

" The height of this ice wall at the nearest point was about 300 feet,
measured from the water's edge ; and the unbroken right line of its
diminishing perspective showed that this might be regarded as its con-
stant measurement. It seemed, in fact, a great icy table-land abutting
with a clean precipice against the sea. This is, indeed, characteristic of
all those Arctic glaciers which issue from central reserviors, or .ners de
glace, upon the fiords or bays, and is strikingly in contrast with the de-
pendent or hanging glaciers of the ravines, whose every line and furrow
and chasm seems to indicate the movement of descent and the mechanical
disturbances which have retarded it. . . .

" As the surface of the glacier receded to the south, its face seemed
broken with piles of earth and rock-stained rubbish, till far back in the
interior it was hidden from me by the slope of a hill. Still beyond this,
however, the white blink or glare of the sky above showed its continued
extension.

" It was more difficult to trace this outline to the northward on account
of the immense discharges at its base. The talus of its descent from the
interior, looking far off to the east, rangec' from seven to fifteen degrees,
so broken by the crevasses, I-owever, as to g'-.e the PlTect of an inclined
plane only in the distance. A few black knobs rose from the white snow
like islands from the sea. The general configuration of its surface showed
how it adapted itself to the inequalities of the basin-country beneath.
There was every modification of hill and valle}', just as upon land."

'■:r
I

138

GLACIERS OF NOKTH AMEUICA.

III"

' The margin of the inland ice on the east side of Greenland has been
explored, especially by Nansen, and found to have the same general char-
acteristics as on the tvest coast, excepting that the strip of mountainous
country intervening between the sea of ice in the interior and the ben of
water to the east is nariov/er, and the ascent steeper. Several large glaciers .
are known on the east ccas^ similar in character to the Humboldt glacier,
and the adjacent watera are crowded with icebergs and with floe ice.

The northern coast of Greenland, at least as far as Cape Washington,
the present limit of exploration, was found by Lockwood and Brainard to
be formed by bold rock headlandd separated by deep valleys and wild,
desolate fiords. The mountains are snow-covered, but glaciei"s are not a
conspicuous feature of the stern landscape, and, so far as known, none of
them reach the sea. I'he character of the coast as seen from Cape
liiitannia, lat. 82° 45', is indicated in the following description bj Liea-
tenant Lockwood : ^

" Owing to the continued bad weather my view of the interior was
mainlj^ confined to what I saw from the two elevations recorded ; and
owing to their comparative lowness, the range of mountain peaks, with
their universal covering of snow, merging and overlapping one another,
made it very difficult to distinguish the topography at all. The interior
land seemed very high and on this account the farthest that I could see
could not have been very many miles removed. I could see (from
Britannia and Lockwood islands) no glaciers that I could recognize as such,
though from the floe, while traveling, I saw a very large one and one or
two quite small. From my farthest I saw mountains to the east, perhaps
twenty or thirty miles distant, and a high mountainous country doubtless
exists along this coast for some distance to the south; the ^hore line of the
fiords invariably begin at the base of steep cliiBfs and mountains. No land
was seen to the north. There was a very noticeable abundance of snow
everywhere."

The above observations on the snowy covering of the north coast of
Greenland were made in May. Judging from the reports of Lieutenant
Peary, who found an abundance of flowers at the farti.est point reached
during his overland journey, much of the land seen by Lockwood must be
bare of snow in late summer.

Far to the north, as discovered by Lieutenant Peary during his fii-st
famous journey over the inland ice, the fringe of mountains bordering the

1 "Report of the Proceedings of the U. S. Expedition to Lady Franklin Bay," vol. 1,
p. 188.

GLACIERS IN THE GltEENLAND REGION.

139

coast of Greenland and intervening between the vast snow plateau of the
Ulterior and the shore line,becomes broader, and the inland ice is limited
in that direction in about the same manner as on the better-known ^/^r-
tions of the coast to the southward. The termination of the inland ice
before reaching the northern border of the land is a signiticant fact, which,
taken in connection with the unglaciated condition of northern Alaska,
suggests that possibly the north end of Greenland was free of ice even
during the glacial period.

The combined observations of many explorere show that the great
reservoir of snow and ice covering central Greeidand, ond supplied solely
from the atmosphere, overflows in all directions through passes in the
bordering mountains so as to form separate ice tongues, but does not enter
the sea bodily, as one might say, on any considerable portion of its
boundary. In this respect the continental glacier of the northern hemi-
sphere differs from the similar ice body in Antarctic regions, which for a
large part of its periphery extends out into the sea, and forms continuous
ice cliffs several hundred miles long. Two phases in the existence of con-
tinental glaciers are thus illustrated. The one at the north is a})parently
receding and contracting its boundaries, while the one at the south is yet
in its full vigor, and is possibly still increasing.

Thanks to the daring and zeal of a few explorers who have traversed
the interior of Greenland, we know what the surface of a continental
glacier is like, and are enabled to picture with considerable confidence the
character of large portions of North America, now thickly peopled, as it
existed during the height of the glacial period.

The first successful attempt to pass beyond the rugged borders of
Greenland and travel on the snow surface of the interior, was made by the
celebrated Swedish navigator. Baron Nordenskiold, in 1883. Leaving the
west coast a little to the south of Disco bay, he traveled inland for
eighteen days over a continuous snow-covered ice field v hich presented the
characteristic features of the neve of Alpine glaciei-s, ajid rose gradually
higher and higher the farther he proceeded. The region of nunataks was
[.assed and a bold advance made over the clear unbroken surface of the
inland ice which stretched away to the horizon as a boundless sea of un-
broken snow. About the only conspicuous details of the surface were
channels in which clear, swift streams coursed along between walls of ice.
These streams were short, however, as they soon i)lunged into crevasses or
moulins and disappeared to join the general subglacial drainage. The
murmur of waters far below the surface told of streams flowing in icy

140

GLACIEKS OF NORTH AMEUICA.

caverns beneath We now know that these features pertain to the outti
border of the ice sheet, extending, it is true, some distance iidand beyond
the fringe of nunataks, but are wanting over the greater part of the
central region.

At tlie end of his inland journey Nordenskiold reached a locality
about 73 miles from the coast and an elevation of 5000 feet. He then
sent his two Lap companions forward on nki^ or Norwegian snow-shoes,
for a distance, it is estimated, of approximately 65 miles, or 138 miles from
the starting point on the coast. The elevation at the farthest poiiu
reached is reported as being 5850 feet above the sea. To the eastward
the surface still continued to rise, showing that the summit of the ice sheet
was not gained. Nansen^ has given reasons for concluding that the dis-
tance traversed by the Lapps after leaving the main party was over-
estimated, and that in reality the farthest point reached was but 118 miles
inland.

The explorations on the inland ice made by Nordenskiold decided once
for all that thj previously entertained hypothesis in reference to the
presence of an area in the interior of Greenland free from ice and perh.ips
inhabited is untenable.

In 1888, Lieut. R. E. Peary, who has since made thref. remarkable
journeys on the inland ice of northern Greenland, made a reconnoissance
in company with Chrit^tian Maigaara, a Danish officer in the Greenland
service, to the east of Disco bay, and some 75 or 100 miles north of the
route followed by Nordenskiold. During this reconnoissance Peary ad-
vanced about 100 miles from the coast and reached an elevation of 7525
feet on the unbi'oken surface of the inland ice.

Impo'-tant as was the first venture that Peary made into the unex-
plored interior of Greenland, it has been far surpassed both by Nansen and
by Peary himself in subsequent years

Dr. Fridtjof Nansen, the most intrepid of Arctic explorers, with four
companions, crossed Greenland from east to west in 1888, between lati-
tudes 64° 10' and 64° 15'. The width of the ice was there found to
be 275 miles. Where the line of march began the ice descended to tlu'
sea and formed a tide-water glacier- but on the west it did not reach within
about 14 miles of the head of Ameralik fiord, or 70 miles from the outer
coastline. The highest position of the vast convex covering of ice under
which the land is buiied was 8920 feet. This elevation was reached at a
distance of 112 miles from the east coast. The gain in elevation for the
1 "The Fii-st Crossing of Greenland " (Longmans & Co., London, 1890), vol. 2, p. 468.

GLACIERS IN THE GHEKNLAND KEGIOxV,

141

lirst 15 miles was 220 feet per mile, and ihence to the summit 38 feet per
mile. As tiie explorers proeeeded westward from the summit the deseent
was still more {gentle, and for fully 100 miles averaged alxiut 25 feet per
mile, a slope which no eye could distinguish from a perfect plain. A
cross profile of the inland ice was thus obtained, which shows a moderate
descent towards the oce'.in on either hand, with a broad, gently convex cen-
tral portion, and illustrates the form assumed by an ice sheet as the result
of accumulation at the surface and an outflow towards the margin.

The highly instructive journeys made by Peary in 1892, and repeated
in part in 1894 and still again in 1895, northejistward from Inglelield gulf
on the west coast, in about lat. 77° 30', confirmed the conclusions reached
during the previous ex])lorations referred to in respect to the character of
the Greenland ice sheet, and seemed to define its northern boundary, at
least in a general wav. In the far north the coast exhibits the same
rugged character as at the south. The border of the iidand ice is broken
by nunataks, but the central part forms a vast plain of snow over whicli
one may travel with dog-sleds and snow-shoes for hundreds of miles in a
continuous line without meeting serious obstructions. So far as the to})Og-
raphy is concerned it is only near the outer margin, where the ice flows
between rugged highlands and mountains tops project above its surface,
that serious difiiculties to travel are met with. The highest point
reached )n the broad, gently convex surface of the ice at the north was
about 8000 feet.

The principal lesson of geological interest learned from the study of the
continental glaciei-s covering Greenland is that such glaciera may originate
on land that is not mountainous and not elevated above the sea, and in
regions where the snowfall is not excessive.

Many of the hypotheses advanced to account for the previous exist-
ence of glaciers over northeastern North America and over north-
western Europe might be tested in the Greenland region at the present
day, and many of them, if so tested, it is safe to say, would lie found
wanting. It is evident that the more familiar we become with existing
glaciers and with the climatic and topographic conditions on which they
depend, including a study of the currents and temperatures of the adjacent
sea, the better able we shall be to interpret the records left by ancient
glaciers and to restore in fancy the condition of large portions of the earth
now thickly inhabited when covered by former ice sheets.

Our knowledge oi the glaciers of Greenland has been greatly extended
by observations made by Prof. T. C. Chamberlin in the summer of 1894,

142

GLACIIOliS OF NOKTll A.MKUICA.

wliile connected witli the second Peary relief expedition. The records ot
the studies then made were not avaihahle when the book now hefore you
was written, although in revising it several references to them have hccu
introduced.

A condensed account was given by Chamberlin of his observations in
(ireenland in the form of a presidential acUlress before the (icologiciii
Society of America, at Baltimore, in I)cccmbe» 1804, and subsequently
printed in the bulletin of the Society.^ A much jnore extended record
has since been jjublishcd in the .Journal of (Jeology. ^ These reports con-
tain a critical ai:d detailed account of glacial 2)henomen,a. Not only are
the actual conditions as they nov/ exist in the portion of Greenland visited
minutely recorded, but general principles are discussed that have a bear-
ing on glacial phenomena in other regions and on the interpretation of the
records of formerly glaciated countries.

Among the more interesting results of these recent studies is the con-
firmation of the reports of previous travelers in reference to the character
of the })recipitous and even overhanging precipices in which the glaciers
of the far north frequently end. The " Chinese Wall " described by Lock-
wood and Hrainard, which, to persons familiar with glaciers in temperate
latitudes only, a})peared to be such an abnormal feature, is shown by Chani-
bcilin to be chaiacteristic of the manner in which Arctic glaciei-s terminate.
Many of the photographic illustrations issued in connection with the
accounts of recent studies referred to bring out this feature with almost
startling reality. Two of these pictures, through the kindness of Pro-
fessor Chamberlin, are reproduced on Plate 22.

Another fact of great interest is the very definite stratification of many
of the glaciers in the far north. I)i this respect the sections displayed at
the extremities of the tongues of ice extending out from the central Green-
land sheet, rese ml >le the sections exposed in the sides of crevasses in the
neve regions of more southern mountains. In fact, several of the phases
of the northern glaciers suggest that they correspond more nearly with the
neves of Alaska and of Alpine regions generally than they do with
'' glaciers proper." In a certain sense they may be said to be examples of
"arrested development." The glaciers of the far north, it appears, are
frequently as definitely bedded and as beautifidly laminated as the best
exanqjles of sedimentary rocks. This resend)lance to rock exposures is
still farther increased by the fact that in some instances t e stratified ice

1" Recent Glacial Suidies in Greenland," Bull. Geol. Soc. Am., vol. 0, pp. 109-?20.
2 Vols. 2, 3, ami 4. , .^ -

(Ji-AC'iKiis OF Nonrii Amkiiua.

kX •

■^l«>f....

■■'•^-^^■^'■- .Kji-

^'S^

Plate 22.

>v^^/"'

1' ~ ^^"S!^-

<:V:

Fig. a. -FRONT OF BRYANT GLACIER, GREENLAND.
Showing viTtii'.il Willi and .'ilriitilioulidu of the ice. (After T. C. C'hiiim)erlin.)

fi^BM^^^W^BI^^MB^^^^B^Bi^BM^B^BMBBBi^^^^^^hB^M^Mmi Mil V

^g|HBHUi|H|flK^^.; ~

^^^^^^^^^I^^^^^^^^^^^^^^^^^^^^^^H^^HRISk''^?

■WIT"--- --.r

F'G. B. — PORTION OF SOUTHEAST FACE OF TUKTOO GLACIER, GREENLAND.
Showing projection of the upper layers and the Huting of their under surfaces. (After T. C. ChauibcrliuJ

OLACIKIIH I)K NoilTII AMKUK A.

I'LATi; 2-2.

c^ A r-o/^ki*T- ^\ r- rtrw/kk.iT- /^ i * ^ i r- f^ ^ >^ ^ ^_._l-. — ^

GLACIEUS IN THE GUEEXLAND REGION.

143

is folded and contorted in the Uiiinner fiXMjuently to bo observed in gneiss
and schist, and is also faulted and overthrust. These structural features
may be seen in the Malaspina ice sheet and in other glaciers of tenijjerate
regions, but nowhere, so far as known, on such a grand scale or such
clearness of details as in (ireenland.

Accompanying and frequently intimately associated with the marked
stratification of the (ireenland glaciers is the occurrence of debris in well-
defined layers. The scarps at the extremities of the glaciei-s, as stated by
Chamberlin, "usually present two great divisions, an upper trjict of thick,
obscurely laminated layers of nearly white ice and a lower laminated tract
discolored by debris. At the base there is usually a talus slope, but only
sometimes a typical moraine. In the up})er portion bluish solid layers
sei)arate the more pttious ice into minor divisions, and these are grou[)ed
by consolidation into more massive layers. Sometimes the whole U[)i)er
division consists of a single stratum, but more cf)mmonly it is divided into
several great beds separated by quite distinct i)lanes.

" The lower discolored divisions also sometimes consist of one great
stratum, but oftener it is divided into many thick layers, as in the case of
the white ice above. Very numerous partings further divide these beds
into minor layei-s of varying thickness, grading down into delicate
laminations, a dozen or a score to an inch."

The two strongly marked divisions exhibited by this and numerous
associated glaciers seem to indicate that they were formed separately.
To one studying the photogiaphs of these glaciers the marked contrast
between the upper and lower portic>ns suggests that the upper laj-ers
of clear ice have advanced upon the lower dirt-stained layers after the
debris they contain had been concentrated by melting. The two divi-
sions would thus represent two separate stages of ice advance. As
this explanation is not touched upon by Chamberlin, however, it is
probable that there are insuperable objections to it, and that the true
reason of the contrast referred to is less obvious and not fully under-
stood.

After discussing the various ways in Avliich glaciers may become strati-
fied, Chamberlin summ.arized his conclusions as follows : " It would ai)pear
that the stratification originated in the inequalities of deposition, emphii-
sized by intercurrent winds, rain, and surface melting : that the incipient
stratification may have been intensified by the ordinary processes of con-
solidation ; that shearing of the strata upon each other still further
emphasized the stratification and developed new horizons under favorable

144

ULACiiSUS OF NUKTU AMKUICA.

I i

coiiditiniiH ; thrt hasal int'(iimlitii'.s introduced new jdanes of stniiifu-ation,
accoini»aiiied by earthy debris, and that this process extended itself so
far as even to form very niiuntc laminae."

Anotiier phenomenon displayed in a wonderful way at the extremitij^s
of the (Jreenland ^Macier, and not previously noted in other regioits, is the
manner in which certain layers jut out from the faces of tlu; ice cliffs so us
to form projecting cornices. Their appearance is shown in Fig. B, Platii
22. These jjrojections were seen on almost every one of the vertical gla-
cial faces examined, an<l wtre found to vary in width from a few inches to
one or two feet, and in rare cases to reach eight, ten, or fifteen feet. 'J'lu;
under surfaces of the cornices are frequently fluted, as may be seen in t}ic
accompanying illustration. These cornices at Hrst sight appear to be due
to a thrusting ftaward of the edge of an individual layer beyond the next
layer below. Movement along shearing planes seems, then, to be indicated.
As shown by Chamberlin, however, if this jjrocess is really in action, the
results produced by it in the unequal extension of various layei-s at the
extremities of the glaciers, are modified and masked to yome extent by
unequal melting. Each layer of clear ice which projects so as to form a
cornice usually has a dark dirt-stained layer below it. The dark layer
absorbs heat more ra})idly than the clear ice and is consequently melted
back more rapidly. The fluting on the under side of the cornices, which
it wjis supposed might be produced by the ice being pushed forward over
stones or inequalities in the hayer beneath, Avas found on further study, to
be due, to a considerable extent at least, to water which trickled down the
face of the overlying layer. In some instances, hoAvever, the junction
plane between a i)rojecting layer and the stratum beneath was itself found
to be fluted. This and other evidence favors the idea that planes of shear
are the initial cause of the unequal projection of various layei-s in the
terminal escarpments. The development of such planes of shear seems at
first opposed to the commonly accepted explanation of the character of
glacial motion, but as the cornices are formed by the advance of layers
of clear ice over other dark layers, the shearing planes may be due to
unequal rigidity caused by the debris in the lower layer, and thus still be
in harmony with the hypothesis that ice flows as a plastic solid.

Measurements made by Lieutenant Peary, of the flow of Bowdoin
glacier, in about latitude 77° 45', showed that the rate during the month of
July was four-tenths of a foot at the southwest point, near the east border,
and 2.78 feet at the farthest point, near the center, with an average of
1.89 feet for the whole.

ULACIEUS IN TUB OUKKNI.AND UEUION.

145

Ore of the most interesting of (^liiPnlKMlin's disioveries, as previonsly
mentioned, is tiie presence of a small driftlcss area, on the shore of Howdoin
hay, in whieh the rocks are deeply decayed. Evidence is thus furnished
that no great extension of ice in the region referred tohasoccnrred within
re(!en^ geological tinier. It is to he renu'inhertjd, however, that Ingelield
gulf is to the west and on the side of the great (ireenlaiul ice sheet, the
How of which is supposed to he mainly southward. The tongues of ice
that c me down to the sea, or approximately to that level, may he the
lateral drainage of the partially stagnant horder of the main snow field,
and conse(iuently would he less affected hy an increase in accumulation
than the secondary glaciei-s farther south.*

Since C'hamherlin's visit to (ireenhmd in connection with the second
Peary relief expedition, a third expedition of the same character visited
that region in the sunnner of 1895. Prof. 11. 1). Salishury was a memher
of tliis last company, and, it is to he exi)ected, will make many additions
to the glacial observations previously obtained. Salisbury's reports will
jirohablybe pul)lished in the Bulletin of the (icological Society of America
and in the Journal of Geology.

1 I liave been led to make this su,i,'ge8tion from certain occurrences observed in Alaska,
liayden glacier, to the east of Mount St. Klias, Hows i)ast the )'"ail of a deep, hi;;li-f;rade lateral
valley without sending a tongue of ice into it. In iiscending the lateral valley one sees in
front of hini a wall of ice ISO or 200 feet lugli, formed by the border of ilayden glacier. Tho
ice in this wall is practically stagnant and protrudes but slightly into the lateral valley, although
th( central current of the glacier flows past ita entrance and joins the Malaspina ice sheet sev-
eral miles to the south. The conditions there seem to be similar, althougli on a much smaller
scale, to those found in the Ingefield region. It thus appears possible that a decided increase
in the main Greenland ice sheet might occur, the direction of tlow being soulliward, without
greatly changing the conditions in the lateral ice tongues that branch oft from tlie side of the
main current. These condilioiis may also account for the extreme sluggishness of tho small
glaciers about Ingefield gulf.

CHAPTER VIII.

CLIMATIC CHANGES INDICATED BY THE GLACIERS OF

NORTH AMERICA.i

It ^as been shown by Dufor ^ and othei's that in general the glaciers
of Eurojie and Asia are retrograding; that is, their extremities are ^\ith-
drawing farther and farther up the valley througli which they flow. Sim-
ilar changes are known to be in progress in the glaciers of the southf ni
heinisphere, but ^vhether a general recession is there in progress has not
been satisfactorily determined. The changes observed in the glaciers of
Europe and Asia make it important to ascertain If evidence of similar
climatic oscillations can be obtained from a study of the ice bodies of
North America. Whether the observed variations in the lengths of exist-
ing glaciers are wholly due to changes in their climatic environment, or
ai'e influenced to some extent by other conditions, will be briefly con-
sidered in the closing paragraphs of this chapter.

In the preceding portion of this book several references have been
miule to recent changes in the glacier described. The bearing of these
observations, however, on the study of the conditions governing the origin,
growth, and decadence of glaciers, and on still wider generalizations in
reference to the origin and decline of glacial epochs, is such as to warrant
some repetition.

The evidence thus far gathered concerning recent changes in the
glaciers of North America is remarkably consistent, and shows that with
the exception of a single glacier in Alaska and perhaps also of some of
the Greenland glaciers, they are all experiencing a general retreat. It
must be remembered, however, thac no precise and accurate studies in this
connection have been made. Almost all of the information in hand is ot
a qualitative character, obtained for the most part incidentally in connec-
tion with other studies. While the conclusion that the glaciers are
retreating is apparently well founded, more detailed observations will

1 This chapter is a reprint, with slight modifications, of a paper by the writer in the
American Geologist, vol. 9, 1802, pp. ii22-ii3(\.

a Bull. Soc. Vaud. So. Nat., vol. 17, 1881. pp. 422-426.

CLIMATIC CHANGES.

147

probal>ly show that. this is accomplished by many minor osciUations
which may include periods t>f local advance.

Character of the Evidenc*?. — Evidence of the advance or retreat of
the ends of alpiiie glaciers, or of the borders of piedmont and continent d
glaciei-s, may be obtained ni various ways. Glaciei-s which are advancing
sometimes plow into the debris in front of them and force it up in concen-
tric ridges, usually with the formation of cracks in the soil. The surfaces
of the ridges formed in this way are frequently covered with vegetation,
which in addition to their forms and the character of the material of which
they are composed, serves to distinguish them from terminal moraines.
When a glacier advances into a forest, the trees are broken off and piled
in confused japs about the margin of the ice. The upper surface of a
glacier is known to flow faster tlian the ice below, aiid an advance is prob-
ably aoomplished by the upper surface flowing over and burying the ice
which rests on the ground. For this reason advancing glaciers usually
present bold scarps at their extremities, and in general, are not covered
witli a broad shee^ of debris.

\n retreating glaciers the layei-s of new snow deposited on the n6v6
fields and changing to ice as they flow downward are melted before reach-
ing the end of the ice streams, and the slow-moving ice at the bottom is
thus left exposed and melts away. The retreat is accomplished not by a
contraction of the ice body, but by the melting of its distal extremity.
The ice which is not covered by the advance of fresh layei^s, melts at the
surface, and the englacial debris is concentrated at the surface. When
a sheet of debris of this character is extensive and cover's the lower
portion of a glacier from side to side, it indicates that the ice beneath is
practically stationary and consequently is melting and retreating. The
ends of retreating glaciers frequently have a gentle surface slope, and in
many instances are so completely concealed by debris that the actual ter-
minus of the ice cannot be distinguished. When the moraines are heavy,
however, and espe(ially when they are clothed with vegetation, the melt
ing of the ice beneath is greatly retarded, and in some observed instances
the glaciers thus protected terminate in bold scarps.

When the end of a glacier recedes more rapidly than soil can form on
the abandoned area, so as to admit of the growth of plants, a desolate
tract is left about its end, on which concentric lines of stones and boulders
may indicate halts in the retreat. Barren areas of this nature, when the
lack of vegetation is not due to the action of watt • from the ice, are good

148

GLACIERS OF NORTH AMERICA.

evidence of recent glacial recession. When glaciers.which flow tiirough a
valley having steep sides, become stagnant, a general lowering of the sur-
face, decreasing up stream, takes place, which leaves the bordering slopt.-*
bare of vegetation. The action of rain and rills on such surfaces may
indicate to some extent the length of time they have been exposed. The
presence of fine glacial debris on slopes from which it would be easily
washed by rain may also furnish evidence in the same connection. Retreat-
ing glaciers sometimes leave detached masses of ice which are melted in
the course of a few yeai-s, and hence when present indicate rapid changes.
The amount of sulKierial ei'osion on glaciated areas may also serve to
indicate the length of time they have been exposed.

These various classes of evidence usually enable one to determine defi-
nitely whether a glacier has recently advancet' or retreated, and may some-
times afford a clu.. to the rate of these changes. When an opportunity is
afforded for detailed study, various surveying and photographic methods
may be employed. If observations can be continued season after season,
the limits of a glacier at various times maybe recorded by monuments, by
marking the position of its margin with asphaltum,etc. Instructions in this
connection have been published by Prof. H. F. Reid.^ In the study of tlie
glaciers of America we have, with the exception of Muir glacier, no defi-
nite quantitative measurements, and must rely on such phenomena as have
been indicated.

California. — Some of the small glaciers in the High Sierra, as already
described, have barren areas about their extremities, showing that they
are slowly receding. No measure of the rate of this recession has been
attempted.

Observations by J. S. Diller, of the United States Geological Survey,
on Mt. Shasta indicate that the glaciers in northern California, like those
farther south, are retreating. Evidence of this is furnished by barren
areas about the ends of several of the glaciers and by a conspicuous lateral
moraine on the side of the Whitney glacier, which in 1887, was about
twenty-five feet above the level of the adjacent ice.

"11

Oregon and Washington. — The glaciers on the Cascade mountains
have been visited by a number ot persons, but I have been unable to

»"The ^a^iation9 of Glaciera," Journal of Geology, vol. 3, 1895, pp. 278-288. This
paper contains references to other puulications in which methods of observing changes in
glaciers are described.

CLIMATIC CHAN'GEH.

149

obtain satisfactory evidence of advance or recession. An inspection of
photograplis of the glaciers on Mount Rainier indicates tliat they end in
areas bare of vegetation, which presumably were recently occui)ied by
ice.

BritiHh Columbia. — The glaciei-s of British Columbia, altliougli
numerous and important, are but imperfectly known, and only a few
observations on recent changes have been made. Many of these glaciers,
however, have been seen by Dr. G. M. Dawson, who informs me that in
no instance are there evidences that they have recently advanced, and that
he consider it safe to assume that they are either stationary or slowly
receding.

R. G. McConnel, of the Canadian Geological Survey, has kindly
informed me that the glaciei's, both on tlie Stikine river and in the
Rocky mountains, have shrunken back from fresh-looking moraines, and
that the intervals between the ice and the moraines, in all instances
examined by him, were destitute of trees and contained but little vege-
tation of any kind. In his opinion a marked retreat has occurred within
the last century or two, but whether it has been in progress during
the past one or two decades cannot l)e decided from the evidence in
hand. Observations made by Macoun and Ingei"soll confirm this con-
clusion.^

The Illecellewaet glacier at Glacier station, on the Canadian Pacific
Railroad, in the spring of 1891, was bordered by a bavren area, between
the ice and the encircling forest, several hundred yards in breadth, which
had evidently been but recently abandoned by the glacier. A small
moraine on the western side of the glacier also suggested a recent shrink-
ing of the ice. The evidence of a recent retreat of this glacier hsis also
been noted by W. S. Green.^

An absence of vegetation al)out the extremity of one of the glaciers on
Stikine river was noted by Blake,^ and may probably be taken as an indi-
cation of a recent retreat of the ice. A legend current among the Stikine
Indians indicates that two glaciere on opposite sides of the stream were
formerly united and that the river then flowed through a tunnel beneath
the ice.

^"Mountaineering in British Columbia," by Ernest Ingersoll, Bull. Am. Geog. Soc,
vol. 18, 1880, p. 18.

2 "Among the Selkirk Glaciers," London, 18iK), p. 09.
' American Journal of Science, vol. 44, 1 307, pp. 90-101.

150

GLACIERS OF NOUTH AMERICA.

Alaska. — The evidence that a general retreat of the glaciers of Alaska
is still in progress is abundant, and in a few instances is of quantitative
value.

Lynn Canal. — About this magnificent inlet, as previously described,
there are many ice streams of the alpine type, which descend nearly to sea
level, but none of them are now actually tide-water glaciers. About the;
ends of many of them there are dense forests of spruce trees which musl
have been growing for at least one hundred and fifty years, but between
the forests and the present terminu.s cf the ice there is, in several instances,
a barren area covered with morainal and alluvial deposits and bearing every
indication of having but recently been abandoned by the glaciers.^ These
conditions are especially noticeable at the extremity of the Davidson
glacier. Between the present terminus of the ice and the encircling foresi
there is a barren tract half a mile broad, which has been left by a retreat
of the ice so recently that vegetation has not been able to take root upon
it. A decided retreat of the ice has here recently occurred, and to all
appearances is still in progress, but no observations of its rate have been
made.

Conditions similar to those seen at Davidson glacier were observed in
connection with several otlier ice streams in the same region. In Taku
inlet, the Norris gl.acier comes down to sea level, but is separated from the
water by broad mud flats. There is no indication that this glacier has
recently advanced, and an accumulation of debris over its surface and
about its extremity indicates that it is melting away- The Taku glacier,
near at hand, is of the tide-water type ; and evidence of recent changes in
the position of its terminus is wanting.

Glacier Bay. — The evidence of recent changes in Muir glacier has
been presented by Professor Wright,'^ who has shown that it has quitt'
recently been both more extensive and of less size than at present. Ad(U-
tional evidence of these changes has been supplied by Reid,^ who con-
cludes that Muir glacier and other ice streams now discharging into Glacier
bay, were formerly much more extensive than at present, and at the time
of Vancouver's expedition, in 1794, probably occupied the whole of the

1 Bull. Geol. Soc. Am., vol. 1, 1890, p. 152.

2 " The Ice Age in North America," by G. Frederick Wright, Few York, 1889, pp. 61-&7.
* " Studies of the Muir Glacier," by H. F, Reid, in National Geographic Magazine, vol.

4, 1891, pp. 34-12.

CLIMATIC CHANGES.

151

bay to a point some distance below Willoughby island. The retreat
during one hundred years is thought to l>e in the neighl>orhood of fourteen
miles. This conclusion, however, rests on certain passages in the narrative
of Vancouver's voyage,^ which may possibly reter to floating ice, and not
to actual glaciere, and therefore do not have the quantitative value indi-
cated above. But under any plausible rendering of Vancouver's account
it does not seem possible to escape the conclusion that the ice in Glacier
Day was far more abundant at the time of his visit than in recent yeai-s.

Observations made by Wright and Keid in 1886 and 1890, respectively,
show that Muir glacier has retreated during this interval more than 1000
yards. This observed rate of recession would, if continuous for one hun-
dred years, produce a retreat of approximately fifteen miles, and affords
ground for believing that the great retreat supposed to have occurred since
Vancouver's visit is approximately correct.

John Muir has kindly contributed the following note concerning the
retreat of the glaciers of southeastern Alaska, which conrirms the evidence
^ already presented :

" All the glaciere that have come under my observation in southeastern
Alaska have retreated and shallowed since first I became acquainted with
them in 1879 and 1880. Those in which the declivity of the channels is
least have of course receded the most. During the ten years between
1880 and 1890, Muir glacier has receded about one mile, at its mouth in
Muir inlet."

St. Ellas Region. — Much space could be occupied in recording obser-
vations which indicate a general recession of the glaciere about Yakutat
and Disenchantment bays and along the adjacent ocean shore, but a brief
summary of this evidence is all that seems necessary at this time.

The lower portions of a large number of glaciera in this region are
completely covered by continuous sheets of debris which has been concen-
trated at the surface through the melting of the ice. This debris is not
being carried forward and deposited in terminal moraines, but i^; distributed
over the surface of the ice in a thin sheet, and marks the stagnant condi-
tion of the glaciers on which it rests. In several instances, especially on
the outer border of the Malaspina glacier, the moraines resting on the ice
are clothed v/ith vegetation, which over many square miles forms a dense
forest, composed principally of spruce trees, some of which are three feet

1 "Voyage of Discovery around the World," by Vancouver, vol. 5, pp. 420-423. Quoted
by Wright in " Ice Age of North America," pp. 66-67.

152

GLACIERS OF NORTH AMERICA.

ill diameter. Within the forest-covered border and forming a belt concen-
tric with it there is a barren tract covered with stones and bouklers. The
forests growing on the glacier and also thousands of lakelets, both in the
outer border of the barren moraine and in the adjacent forest-covered
moraine, indicate conclusively that the ice sheet is stagnant and conse-
quently wasting away. On the coast bordering the Malaspina glacier on
the south, there were formerly two projections called Point Rio and Cape
Sitkagi, which were noted, by the explorei-s one hundred years ago. In
traversing this coast in 1891 I found that no capes exist at the localities
referred to. At the site of Cape Sitkagi there is evidence that the sea
has recently invaded the j^lacial boundary. On the sides of many of the
alpine glaciei's in the adjacent mountains there are steep slopes bare of
vegetation although well below the upper limit of tree growth on adjacent
areas, which indicate that the ice streams have recently shrunken within
their beds. My conclusion after two visits to the glaciers in the St. Elias
region is that without exception they are rapidly retreating.

Near Point Manby there is a locality where the Malaspina glacier has .
recently advanced about 1500 feet into a dense spruce forest, cutting off
the trees and sweeping them into confused heaps. After advancing the
ice retreated, leaving a typical morainal surface covered with lakelets.
This is the only instance of a recent advance that has come under
my notice in Alaska.

The head of Yakutat bay was visited by Malaspina in 1791, and again
by Captain Puget in 1794. Each of these explorers found the inlet
blocked by a wall of ice from shore to shore. No other observations in
this connection were made until my visit in the summer of 1890.^ From
what may now be observed it is evident that the Turner and Hubbard
glaciers, which come down to the water at the head of the inlet and break
off in bergs, must have extended some five or six miles beyond their
present position at the time of Malaspina's and Puget's visits, and were
then united so as to completely block the entrance to Disenchantment bay,
which is a continuation of Yakutat bay. These observations show conclu-
sively that the gl.aciei-s mentioned have retreated five or six miles within
the past one hundred years. The small recession that has here taken
place, in comparison with the changes reported in Glacier bay, during the
same time, is probably due co the fact that the n^v^ from which Muir

1 Map indicating the position of the ice in 1791 is shown on Plate 7, and its extent in
1800 on Plate 8, of my " Report on an Expedition to Mount St. Elias," in National Geograpliic
Magazine, vol. 3.

CLIMATIC CHANGES.

153

glacier flows is much lower than the snow fields drained by the Hul/bard
and Turner glaciers, and presumably more sensitive to climatic changes.

«li

North Side of tlie St. Elias Mountains. — Dr. C. Willard Hayes, of
the United States Geological Survey, in crossing from Selkirk house on
the Yukon river to Copper river in 1891, passed for a portion of the way
along the northern border of the great system of mountains which culmi-
nates in Mount Logan and Mount St. Elias, and discovered several large
glaciers of the alpine type flowing northward from the neve field north of
Mount St. Elias. and also other glaciers draining ueve fields about Mount
Wrangell and flowing southward. Respecting the evidence of recent
changes in these glaciers, Dr. Hayes has kindly supplied the following r.otes:

" Two large glaciei-s and many small ones were seen flowing from the
St. Elias mountains northward into the White Fiver basin. Another flows
from the southeast into the pass and drains into both the White and Copper
River basins. About 'e head of the Nizzenah are four large and many
small glaciers. Flowing into Copper river from the coast range are four
or five glaciers, one of them — Miles glacier — being larger than any seen
further in the interior. Observations were thus made on twelve glaciers,
and, with one exception to be described later, all show a more or less
rapid recession. The evidence of this recession in most cases is the accu-
mulated moraine covering the terminal edge of the glacier ; or where
there is not sufficient englacial drift to accumulate and form a protective
mantle, the stagnant ice melting to a feather edge. The White River lobe
of Russell glacier is of the moraine-covered type, while the Nizzenah
Icbc lias the feather edge. On the Klutlau and Russell glaciers the outer
portion of the moraine-covered ice supports a dense vegetation, which
becomes gradually more scanty and disappears about half a mile from, the
edge of the ice. The 'cession of the smaller glaciers along the Nizzenah
appears to have been more rajjid than the advance of the vegetation, so
that between it and the ice there is a belt of bare moraine.

" Miles glacier terminates in an ice clifl: fronting upon Copper river,
and the river has as yet cut only part way through the dam formed by the
northern lateral moraine. This moraine must, until very recently, ht.ve
been backed up by the glacier itself, though the front of the latter has
now retreated two miles to the eastward.

" While the fact of recession is manifest, the rate is more difiicult to
determine. In one case, however, it is possible to connect the amount of
recession with an important episode in the history of the region, namely,

154

GLACIERS OF NORTH AMERICA.

the eruption of a widespread deposit of volcanic ash wliiih extends from
near the head of the Pelly westward to Scolai pass. With regard to the
age of tliis deposit Dr. Dawson says : ^ ' While the erui)ti()n mnst have
happened at least several hundred yeai*s ago, it can scarcely l)e sup[)ost'(l
to have taken place nu)re than a thousand years hefore the })resent time.'

" For a distance of about three miles in front of the Klutlan glacier
there is a deposit of moraine material perhaps 200 feet thick, com[)osed of
volcanic ash and angular rock fragments. This evidently fixes the position
of the glacial front at the time of the volcanic erui)tion, and the amount
of recession since that e-vent. It is interesting to note that on the present
glacier surface the volcanic sish is found only a short distance from the end,
showing that since the eruption, while the front of the glacier has receded
about three miles, nearly the whole mass of the glacier has been renewed
by fresh addition from its source.

" The single exceptional case already referred to is the Frederika glii-
cier, which seems to be advancing its front instead of retreating. It has
its source in the lagh mountains forming the eastern membei-s of the
Wrangell group, and flows south in a lateral valley, joining the valley of
the Nizzenah at right angles. The front of the glacier is parallel with the
river and about three-fourths of a mile from it, the intervening space being
a gravel plain. The glacier terminates in nearly a vertical ice cliff about
250 fecL high. It is slightly convex, and stretches entirely across the
valley, about a mile in length. The surface of the glacier is free from
moraines, but is extremely rough and broken, unlike the ordinary surface
of stagnant ice at the end of a retreating glacier. At the foot of the cliff
is a small accumulation of gravel and fragments of ice, probably pushed
along by the advancing mass.'^

"An explanation of this anomalous case is suggested. Ten miles to
the westward of the Frederika another much larger glacier flows into the
valley of the Nizzenah. This is formed by the union of three separate
streams, and of these the eastern appears to be retreating much nioic
rapidly than either of the others. But this eastern branch probably has
its source in the same basin as the Frederika glacier, and it seems not
impossible that by some means the drainage has been diverted from the
western to the eastern outlet, thus causing the rapid retreat in the former
glacier and advance in the latter."

1 Report on Yukon District, p. 46, B.

2 Tliis is the only authentic instance of an advancing glacier known on the west coast of
North America. I. C. R.

CLIMATIC CHANGES.

155

Cireenlaiul. — Kefjfiinling recent changes in the ice sheet of Greenhind
there is but scanty evidence, and such observations as have lx;en made on
the advance and retreat of the margin of tlie ice are conflicting. Holts
found in 1880, between hititude 01° and <J5° 30', on tlie west coast, accord-
ing to Lindahl,^ that " the border of the ice ajjpeared to have retreated
quite recently in niany j)laces ; in othei's, it had decidedly advanced."
Nansen'^ remarks in this connection that we cannot even conjecture what
the present conditions are, and thinks that the ol)servations show that
there is no strong tendency either toward advance or retreat. Warren
Upham,^ Avho has recently reviewed the literature relating to the (ireen-
land ice sheet, informs me that in his judgment the ice is now slightly
increasing in thickness and generally . extent. This conclusion rests
largely on the general absence of debris on the borders of the ice sheet.
His studies have also led him to the conclusion that Greenland, in common
Avith other portions of the northeast border of this continent, is now having
an api)reciable increase in cold.

The observations of those Avho have traversed the inland ice agree in
showing that nearly its entire surface is in the condition of a ndve, and
suggest that growth and not retreat must be in progress. The absence of
debris on the borders of the ice sheet referred to by Upham, is important
in this connection, and seems to indicate that no great waste of ice occurs
before it is discharged into the sea. So far as one may judge from the
observations of others, it seems as if the evidence available i)oints to an
increase of the ice sheet, as sui)posed by Upham ; but the accuracy of this
conclusion is questionable, and Dufor, in a paper cited in the beginning
of this chapter, is inclined to the opposite opinion. He states that in 1880,
he made a communication on the retreat of the glaciers of Europe and
Asia before a scientific congress at Reims, and that, during the discussion
which followed, one of the persons present who had l)een in Greenland
several times mentioned that he " had noticed that the glaciers of that land
had also retreated considerably." It is known that the glaciers of Green-
land were much more extensive during a former epoch than at present,
and left records at an elevation of 3000 feet above the present ice surface.*

1 American Naturalist, vol. 22, 1888, p. 59.3.

2 " First Crossing of Greenland," vol. 2, p. 491.

* The conclusions of Mr. Upham are also contained in the following papers : " On the
Cause of the Cold of the Glacial Epoch," American Geologist, vol. 6, 18JK), p. .3.36 ; and "The
Ice Sheet of Greenland," American Geologist, vol. 8, 1891, p. 150 ; " Criteria of Englacial and
>Subglacial Drift," American Geologist, vol. 8, 1891, p. 385.

* American Journal of Science, Third Series, vol. 24, pp. 100, 101.

150

GLACIERS OF NORTH AMERICA.

It may be .suggested that the observations referred to by Dufor possibly
rehito to these ancient records.

\V«'lglit of tlio Evidence. — The observations suninuirized in ihis
chapter in reference to the Cordilleran region, altliough unsatisfactory in
many ways, indicate, with a single exception which seems to have a special
explanation, that the ice bodies in tliat region are retreating. This con-
clusion not only rests on direct observations of several individuals, but is
sustained by negative evidenca as well. An advance of a glacier, espe-
cially in a forested country, is' apt to be strongly marked, and would attrait
the attention of even a ciisual observer ; but in no instance, with the excc})-
tion reported by Dr. Hjiyes, and the slight extension on the border of the
Malaspina glacier already mentioned, has a recent advance been reported.

The fact that the glaciers at the head of Yakutat bay have retreated
several miles within the past one hundred yeai-s, as well as the still greater
recession of the glaciers of Glacier bay during the same period, indicates
that the present general recession of the glaciei"s of the Pacific coast has
probably been in i)rogress for more than a century. During tliis time there
must have been many minor oscillations which our imperfect observations
do not detect, but the conclusion that the general movement has been
backward is well sustained.

Theoretical Considerations.

The variations that glaciers are undergoing have received special atten-
tion during the past few years. A large body of evidence in this connection
is being collected, especially by members of various Alpine clubs, but as
yet these studies have been confined principall}' to the glaciei-s of Europe.
The importance of this inquiry led the International Congress of Geolo-
gists, at its meeting at Zurich in 1894, to appoint a committee for tlie
special purpose of collecting data all over the world, with the view, if pos-
sible, of discovering a relation between the variations of glaciere and
meteorological phenomena.^ An attempt to discuss systematically the
observations thus far recorded in this connection would be out of place ut
the present time, since no detailed studies have been nade. of American gla-
ciers ; but a few suggestions in reference to the directions in which this
investigation seems to point may be of interest to the reader.

All the explanations of the observed variations in the length of gla-
ciers thus far offered are based on the supposition that they are due to

1 H. F. Reid, " Variations of Glaciers," Journal of Geology, vol. 3, 1895, pp. 278-288.

CLIMATIC CHANOKS.

167

climatic changes. In resjiect to the greater oscilhitions it seems as if no
other (ionclusiou coiiM Ihj expected, hut minor changes, as I shall attempt
to show, may he due to other conditions.

Tile statement made in the opening paragrai)h of tlie present chapter,
to tlie etl'eet that the glaci VH of Europe and Asia are retreating, is perhaps
misleading, as it refers to liie algebraic sum of advances and retreats dur-
ing a term of years. VVitliin the cycle referred to there have undoubtedly
been many minor fluctuations which vary not only in amount but in (Urec-
tion, in different glaciers. In several instances, certain membei-s of a group
of glaciers have advanced during recent years, — '^ile othei-s in the same
group have remained stationary or retreated, and vice versa. Opposite
movements in ghiciers which so far as one can judge are exposed to the
same climatic changes have not been satisfactorily explained.

Changes in the length of a glacier may evidently result frcmi (1) vari-
ations in the amount of snow sui)plied to its neve region, (2) to changes in
tlie rate of melting, or (3) to fluctuations in the rate of flow.

Variations in the amount of snow added to the n^ve of a glacier, as
shown in part at least by Professor Forel,^ may be considered as of the
nature of a pulsation which is propagated throughout its length. I'he
end of a glacier might therefore alternately advance and retreat in sym-
patliy with vnriations in snowfall that occurred scores of yeai-s and even
centuries before. Two glaciers subject to the same climatic conditions,
but of unequal leilgth, or of the same length but having different mean
velocities, would advance or retreat at different periods for the reason that
the time required for the increment produced by an increase of snowfall
to reach their extremities would be different.'^

It has been suggested that variations in the rate of melting might be
a factor causing the ends of glaciers to advance or retreat. But as loss
by melting is greatest at the lower extremity of a glacier, similar effects
would be expected in neighboring instances, although alpine glaciers that

» Bibliot. Univ. de Genfeve, 1881.

2 Another explanation dependent on variations in snowfall has been suggested by I'ro-
fessor Kichter, who, as stated by Reid (.lournal of Geology, vol. .3, p. 281), "thinks that the
.accumulation of snow in the n^v6 region, even under uniform nieteorological conditions, would
in time produce a great enough pressure to overcome the resistance, due to the friction against
its bed, of the glacier's tongue, which is then pushed forward with a greater velocity, result-
ing in the advance of the glacier ; this continues until the drain on the n6v^ region, on account
of more rapid flow, exhausts the accumulation of snow ; after this the motion almost entirely
ceases, and the glacier melts back until another advance begins. I'rofessor Forel calls this
the ' theory of intermittent flow,' and points out that according to it variations in the size
of glaciers would be entirely independent of meteorological changes."

158

OLACIEU8 OP NORTH AMERICA.

descend into different valleyx mij^ht perhaps Ix; influenced differently. It
is unnecessary to discuss this surrgostion, however, since oliservation on
meteorological changes and on the variations of glaciei-s in the same region
do not sustain it.

While it is customary to refer the advances and retreats ohserved in
glaciers to climatic changes, and although opposite movements in glaciers
exposed to the same meteorological conditions may, perhaps, as shown
above, be explained in this way ; yet I venture to suggest that there is a
principle involved in the behavior of glacici-s themselves that might bring
about analogous results. I refer to the influence of debris on the flo\v of
ice containing it.

As is well known, a concentration of debris takes place at the end of
a glacier, especially when it is slowly retreating. This is due to the fact
that while the volume of the ice decreases, the amount of debris it con-
tains remains practically the same. The percentage of foreign material in
a given volume of ice is thus increased. The rate of flow of ice, however,
other conditions remaining the same, decreases as the percentage of
contained debris increasts.^

As the percentage of debris in the extremity of a glacier increases, the
flow of the ice will slacken, and when the concentration reaches a certain
point, stagnation will result. The d<;bris-charged ice will then act as a d.un
and check the flow of the clearer iee above. The effect of such a check in
the advances of the stream will vary with conditions, particularly as there
is a delicate adjustment at the extremity of a normal glficier between the
effects of temperature tending to melt the ice and the advance of fresh ice
from above. Fresh ice may advance upon the debris-charged portion and
become in turn concentrated, thus raising the dam ; or, in the ease of a
growing glacier, may flow over the obstruction and continue to advance
until melting and concentration of debris again causes stagnation at its
extremity, when the process would be repeated. If the glacier is slowly
wasting away, the dam would check the advance of ice from above and
cause it to increase in thickness and to expand in area, thus presenting a
broader surface to the atmosphere. Now, the presence of surface de))ri.s
influences the melting of a glacier in two ways. When small in amount,
especially if dark in color, it promotes liquefaction ; but if abundant, it
protects the ice from the sun and atmosphere and retards waste. In the
case of a slowly retreating glacier that has formed a d6bris-charged ice

1 1. C. Russell, " The Effect of Debris on the Flow of Glaciers," Journal of Geology,
vol. 3, 1895, pp. 823-832,

CLIMATIC CIlANtJES.

159

dum, the melting of the ( leiir, or hut sliglitly chaipeil i('e,ftlx)ve the olwtruc-
tion will go on nmch more rapidly than at the extremity, where the iee i»
covered with earth and Mtones. The iee alH)ve the oiwtruetion migiit then
Ik; melted, leaving the dam to .slowly wiuste away and finally leave a ter-
minal moraine. The retreating glacier hy again eoneentiating debris in its
extremity would again halt, and the [iroeess Ix; repeated.

An explanation is thus suggestetl of the varying l)ehavior of glaeiei"s
under the same elinuitie conditions. Two glaciers supplied in their ndv6
regions with equal quantities of snow, and alike in all respects except in
the amount of debris carried, would undergo the changes outlined above at
different rates. If their percentages of deln'is were the same and other
conditions varied, their periods of halt and advance or retreat wndd again
vfiry. So divei"se are the conditions controlling tiie flow of glaciers that
in no two instances would their pulsations l)e synchronous, even under the
same meteorological environment.

While the greater clianges exhibited by glaciers can only he accounted
for by variation in the supply of snow on their n6v6s, or changes in the
rate of melting, or both of these causes combined, due to meteorological
fluctuations, it seems evident that the minor advances and retreats of
their extremities may be due in part to the effects of debris on the flow
and on the melting of the ice as outlined above.

CHAPTER IX.

HOW AND WHY GLACIERS MOVE.

A REVIEW of the various hypotheses that have been advanced to account
for the movements characteristic of glaciers, necessitates an extension of
the geographical limits set for this book, since the critical investigation
of gl{\eial phenomena vas well advanced in Europe before the fact tliiit
glaciers existed in North America, with the exception of the remote
Greenland region, was known. It is only in recent years that the detailed
study of existing glaciers has been undertaken in this country. Although
Agassiz adopted America as his home, the investigations that placed him
in the foremost rank of glacia!'sts were carried out in Euro^ic. It is to
the physicists and geologists of Europe that we are indebted for nearly all
that has been done respecting the philosophy of glacial motion.

The Nature of Glacial Flow. — Many observations have been made
which show that glaciers have motion, and in probably all instances exhibit
a well-defined flow during some portion of their history. Al^^iough this
matter has claimed a large amount of attention, it is important to remem-
ber that glacial ice frequently does not flow, and that probably some part
of every glacier is stagnant.

The fact that glaciers move was first determined in a qualitative way
by noting the changes that take place in the moraines on their surfaces.
Conspicuous boulders resting on the ice were observed to slowly change
their positions from year to year vath reference to fixed points on adjacent
cliffs. These crude observations lead to measurements of the rate of flow.
In the case of several glaciers of the alpine type, rows of stakes have been
placed in the ice at right angles to the direction of movement, and their
displacement observed by means of surveying instruments from the adja-
cent banks. In this manner changes in the positions of the stakes have
been measured from day to day, and in some instances even from hour to
hour. Many observations of this nature have shown that in the case of a
river-like glacier, the most convenient variety for study, the maximum
motion is in the central part and decreases toward the bordei-s. It has
also been found that the rate of flow is greatest at the rurface, and decreajes
toward thr bottom. When a glacier follows a sinuous course, the thread

HOW AND WHY GLACIEUS MOVE.

161

of maximum current is deflected to the right and left of a medial line, in
the same manner that the swift central current of a winding river is thrown
first against one bank and then against the other ; but the bends in the
sluggish ice current are less abrupt than in the case of the more flexible
water current.

The rate of flow of a glacier varies from locality to locality, through-
out its length, in response to irregularities in the valley it occupies,
unequal distribution of the debris it carries, and other reasons. The rate
of flow also varies with the seasons, being greatest in summer and least" in
winter. Similar but much less pronounced variations occur between day
and night. These seasonal and daily changes comcide with variations of
temperature, the rate of flow increasing with an increase in the amount
of heat that reaches a glacier. It is important to note, however, that
although glaciers are sluggish in cold weather, they continue to flow, in
many instances at least, even in the depth of winter. A flowing motion
in the ice of piedmont and continental glaciers is frequently evideni Ivom
the arrangement of debris on their surfaces. The same fact is shown, also,
by the presence of lobes about their margins which many times become
well-defined streams. Although no measurements have been made of the
manner in which the currents in great ice sheets move, there is vo reason
for supposing thfvt the causes producing them are of a different nature
from those which urge an alpine glacier tluough a narrow valley. If an
explanation can be found for the flow of a mountain ice-stream, it is evident
that it should explain the movements of other types of glaciers as well.

The movements of a glacier are usually greatly modified by local con-
ditions. In seeking for general laws applicable to all glaciers, it will be
of assistance if we can determine what would be the behavior under normal
conditions of an ideal glacier composed of clear ice, flowing down a straight,
even channel of uniform width and with a uniform gradient both of the
valley and of the glacier's surface. Let us assume also that in cross sec-
tion our ^deal glacier has the form of half an ellips3, the division being
along the longer axis. From what is known concerning the behavior of
glaciers we may deternune in what manner our ideal ice stream would flow.

All students of glacial })henomena will agree, I think, that in the ideal
example before us the thread of maximum current would be at the center
of tlie surface, and that the rate of surface flow would decrease uniformly
toward each bank ; also, that the rate of flow would decrease uniformly from
the center of the half-ellipse along any of its radii. The ruinor axis of
the ellipse would divide a cross section of the glacier into two equal and

162

GLACIERS OF NORTH AMERICA.

similar figures, and similar points in each half would have a corresponding
motion which would differ from the motion of all other paints in the cross
section.

Any theory of glacial motion that is applicable to all glaciers should
account for the flow of our ideal glacier, and also explain all changes in
its movements resulting from alterations in the assumed conditions. With
a true and sufficient explanation of glacial motioii in mind, we should be
able to predict what modifications in the flow of our ideal glacier would
result : if, for example, its chaiinel was no longer straight ; if changes
should be made in the gradient of either its bottom or surface ; if the sides
or bottom of its channel should be made uneven ; if its width should
vary ; if the temperature to which it is exposed should change either grad-
ually from its source to its extremity, or fluctuate irregularly ; if the ice
should become unevenly charged with debris ; and in fact any other
changes in environment to which actual glaciers are subject.

The student who has in mind the movements in our ideal glacier, and
attempts to trace the changes that would result from such a combinauon
of conditions as exert an influence on even the simplest existing alpine
glacier, will no doubt be willing to accept the conclusion reached by gla-
cialists that in any existing glacier, no two points in any cross section, and
in fact no two points in any portion of the ice stream, move at the same
rate for any considerable time. In other words, adjacent molecules — or
other feniall divisions into which ice may be assumed 'j be divided —
throughout a glacier are moving at diffeient rates.^ That is, the flow of
glacial ice, in a general way, at least, is analogous to the flow of a liquid,

1 Observations by Messrs. R. H. Koch and Fr. Klocke (Philosophical Magazine, Fifth
Sei-ies, vol. 9, 1880, pp. 274-277) on the movements of a point in a vertical plane in a glacier
indicate that the movements of such a point are much more complex than has been generally
supposed. In the observations referred to it was found that a given point at one time moved
toward the source of the glacier, and at another time toward its extremity. Two adjacent
points were found to move in opposite directions at the same time. The maximum move-
ments occurred in the forenoon, beginning with the irridation of the glacier by the sun.
These morning movements were irregular, but on the whole tended down the valley ; while
at night the resultant in the direction of movement was toward the mountains.

So far as I am aware, these delicate observations have not been repeated, and conclusions
based on them may not apply to glaciers in general.

Messrs. Koch and Klocke do not state what precautions were ;,aken to shield their
instrument from changes of temperature, and it is possible that their observations are in error
from this cause. The difficulty of keeping a transit or other similar instrument in adjust-
ment, when exposed to changes of temperature, makes it desirable that the observations
referred to should be repeated with an instrument so arranged, perhaps with a prism, that a
fixed point on land can be seen at the same time that the movements of a point on a glacier
arc Measured.

HOW AND WHY GLACIERS MOVE.

163

or more nearly to the flow of a viscous fluid. It must be remembered that
in the above attempts to describe the flow of an ideal glacier, and to sug-
gest the nature of the changes that would result from modifications in the
conditions to which it is subjected, the aim has been to obtalu a graphic
idea of how a glacier flows, without attempting to explain why it flows. In
order to learn if possible the nature and mode of action of the natural
forces which cause ice to move, and at the same time become more familiar
with glacial phenomena in general, let us review briefly some of the
principal explanations that have been offered of glacial motion.

Hypotheses of Glacial Motion.^

Several hypotheses in explanation of the characteristic movements of
glaciers have been advanced, but no one of them has thus far met with
[;;eneral acceptance. H is manifestly the duty of the geologist and geog-
rapher, however, to examine these proposed ex[)lanations, and ascertain so
far as is possible how much of each can be safely accepted, even if it does
not afford a sufficient reason for all of the movements known to occur in
large ice masses. By so doing we may, perhaps, clertr the way for renewed
study, or possibly be able to frame an eclectic theory from portions of
previous explanations which will be satisfactory.

The Slidingr Hypothesis. — As far back as 1760, a?" stated by Tyndall,
Altman and Griiner proposed the view that glaciers move by sliding over
their beds. Nearly forty years subsequently this notion was revived by
De Saussure, and has therefore frequently been called " De Saussure's
theory," but is more frequently, perhaps, designated as the "sliding
theory" of glacial motion. Subsequently the hypothesis was ably discussed
by W. Hopkins.'''

Under this hyi>othe8is glaciers are supposed to slide bodily down the
valleys they occupy, in obedience to gravity, and grind away the rocks
over which they pass, by means of sand and stones frozen into their under
surfaces.

* Many reviews of glacial hypotheses have been published ; among those that the student
will find most interesting and instructive are : " Thr^ Physical Cause of the Motion of Glaciers,"
in " Climate and Time," by James CroU, llrst edition, chapters 30, 31 ; " The Great Ice Age,'
by James Geikie, second edition, chapters 3, 4 ; " Illustrations of the Earth's Surface —
Glaciers," by N. S. Shaler and W. M. Davis, chapter 12. The last-named book also contains
a useful list of works on glaciers, published previous to 1881.

2 "On the Motions of Glacier," Philosophical Magazine, vol. 24, 1895, pp. 607-600 :
Also, "On the Theory of the Motion of Glaciers," ibid., vol. 25, 1863, p. 224.

164

GLACIEUS OF NORTH AMEUICA.

It is unnecessary to discuss the sliding hypothesis, since, as is now
unanimously conceded, the normal movements to l>e observed in glacial
ice are of the mitt'.re of an onward flow, accomplished by the mutual dis-
placement of molecules of ice. It is of interest to note, however, that
this early and now totally rejected hypothesis dov^s contain an element
of truth.

Wlien glaciers descend steep slopes they become broken, and even
large r^asses sometimes move short distances by sliding bodily downward.
This, it will be understood, is an exception to the normf'. moveniMits
characteristic of glaciers, and is referred to simply to show that even the
crudest of the hypotheses we are considering contains a grain of truth.

The Hypothesis of Dilatation. — As the movements of glaciers
became better known, the sliding hypothesis just referred to wa'- sup-
planted by the " hypothesis of dilatation," advocated especially by Cliar-
pentier and Agassiz. The basis of this proposed explanntion is that water
on freezing expands and, if confined, will exert a pressure on the walls
retaining it. As water penetrates freely into a glacier through fissures
and capillary passages, it was concluded that it would freeze in such situ-
ations, and thus exert a pressure on the ice containing it, and that a
movement of the ice would thus originate which would take the direction
of least resistance ; and, as alpine glaciers were alone considered, it was
concluded that the direction of least resistance would be down the valleys
they occupy.

Tliis hypothesis, like the one it displaced, met with opposition and lead
to much discussion. Better still, it awakened fresh interest in glacial
studies and led to renewed observations of glacial phenomena.

Among the able opponents of the dilatation hypothesis Avas W. Hop-
kins, who showed, by means of mathematical demonstrations, that the
direction of least resistance to expansion at most points within a glacier
would be vertically upward, and that the assumed cause of glacial flow, if
really in action, would cause a glacier to increase in thickness rather than
advance down a valley.

Many other objections to the hypothesis under review have been
advanced from time to time. It has been shown, for example, that the
changes of temperature to which glaciers are ordinarily subjected do not
penetrate far beneath the surface ; and besides, if glacial flow is due
jolely to the freezing of water within the ice, it should be greater by
night than by day, and greater in winter than in summer, which, as

HOW AND WHY GLAUIEUS MOVE.

165

we know, is the reverse of the truth. These and other objections to
the hypothesis of dilatation have led to the conclusion that it is in-
adequate as a complete explanation of the normal movements of even
alpine glaciei-s.

In closing this brief review of a long and instructive discussion, I wish
to remind the reader that, although the hypothesis of dilatation as a Vv^hole
has been abandoned, the labors of its advocates were not in vain. It not
only served a useful purpose in stimulating inquiry, but that it is based
on a true principle must be conceded even at this time when several
younger and more promising hypotheses are in the field. It cannot be
truthfully denied that water does freeze in cavities and capillary passages
in glaciere, and in so doing does exert a force which tends to move tliem.
What the opponents of the hypothesis have demonstrated is that the force
appealed to is inadequate to brinj^ a" +he results observed, and that it
is not the only force that tends to produce glacial motion.

if'''
I

The Hypothesis of Plasticity. — The attempt to explain the flow of
glaciers, to which this name has been applied, is based essentially on two
principles: 1. Th.at ice is plastic, and will change its form under pressure.
2. That ice in sufficiently large masses, when unconfined, will flow under
the influence of its own might. Each of these propositions has been vig-
orously assailed, and evei, at the present day their correctness is not
admitted by eminent physicists. More will be said in this connection in
advance.

It is stated by TyndalP that the first suggestion in reference to
glacial ice behaving as a plastic body was made by Bordier, in 1773.
Thi^ germ, however, did not bear fruit.

In ] 841 Rendu presented a " Theorie des Glaciei's de la Savoie "
before the Royal Academy of Savoy, in which the idea that glacial ice
behaves as a plastic solid is clearly enunciated. This important discussion
not only of the movements of glaciers, but of many other phenomena con-
nected with them, has been republished, together with a translation in
English, and may be found in most scientific libraries.'^

The hypothesis that glaciers owe their movements to the inherent
plasticity of the ice composing them found its chief advocate in J. D.
Forbes, who first applied the term viscous to glacial ice, and by long con-
tinued study and careful experiments sought to establish a "viscous

J " Forms of Water," 1875, p. 163.

a "Theory of the Glaciers of Savoy," Macmillan & Co., 1874.

166

GLACIERS OF NORTH AMERICA.

theory" of g)acial motion. The formal h; pothesis, as stated by Forbes,^
is : "A glacier is an imperfect fluid or visciuis body, which is urged down
a slope of certain inclination by the mutual pressure of its parts." As the
terms viscosity and plasticity are now strictly defined, although applied to
phenomena which in reality i.ierge together, it is advisable to change the
wording of the hypothesis under review, as first stated, without, ho.^ever,
altering the meaning that was intended to be conveyed. We shall speak
of solids that yield continuous under pressure as a plastic solid, and a fluid
which Hows sluggishly as a viscous fluid.

Tlie conclusion that an alpine glacier flows more rapidly in its central
part than at the sides was fii-st definitely established by Agassiz, and after-
ward verified by Forbes. The flow of a glacier was thus shown to be
strikingly analogous to the flow of a river. This fact has been so well
established, and may be so eaeily verified, that we are justified in saying
that a glacier flows in the same manne" as a fluid body, that is, it advances
owing to differential molecular motion in essentially all its parts. Whether
the flow of glacial ice is due to its plasticity under the influence of its own
weight, or is owing either wholly or in part to other causos, I trust will
appear as we advance.

The propositions on which the hypothesis of plasticity are based must
necessarily be verified before they can be applied in explanation of the
behavior of glaciers. Let us see first of all whether conclusions have been
reached in reference to the plasticity of ice.

Ice, as we ordinarily see it, is a hard, brittle substance, which may be
shattered into angular fragments by a sharp blow. At the first glance it
would seem that scarcely any statement could be farther from the truth
than to say that such a substance is plastic, that is, will yield continuously
to pressure without fracture. Manj' substances, however, like pitch,
asphaltum, etc., which at ordinary atmospheric temperatures are as brittle
as ice, and like it may be broken into angular fragments by a force sud-
denly applied, Avill, if time be allowed, slowly change their form, or flow,
under the influence of their own weight. Many experiments have been
made which demonstrate that ice under sufficient pressure, if slowly
applied, will also change its shape without being broken. Without digress-
ing too far from the main subject in hand, I may state that perhaps the

1 " Travels through the Alps of Savoy and Other Parts of the Tennine Chain, with
Observations on the Phenomena of Glaciers," Edinburgh, 1846, second edition, p. 3(5o.
"Norway and its Glaciers," Edinburg'i, 1863. "Occasional Papers on the Theory of
Glaciers," Edinburgh, 1859.

HOW AND WHY GLACIERS MOVE.

167

most conclusive experiments in this direction have been made by J. C.
McConnel and D. A. Kidd,^ who demonstrated that a bar of ghicier or
other ice, if composed of many crystals, will yield continuously and with-
out fracture to both pressure and tension. That is, it apparently behaved
as a plastic solid. The greatest freedom of motion occurred when the
ice experimented on was near the melting point, and decreased with a
deciease of temperature. At — 2° C. its " plasticity " was twice as great
as at —10^ C.

Further experiments, by McConnel, with bare of ice cut from single
crystals, brought out most interesting results. It was found that when
such a bar with the optic axis of the cryjtal perpendicular to two of the
side faces was subject to bending stress, it would bend freely in the plane
of the axis either at or below the freezing point, but not at all in a plane
perpendicular to it. In the bent crystal the optic axis in any part was
normal to the bent faces in that part. The crystal behaved as if it was
composed of an infinite number of thin sheets of paper, normal to the optic
axis, attached to each other by some viscous substance which allowed one
to slide over the next with great difficulty.

The results of the experiments just cited seem to show that while ice
composed of many crystals yields to both pressure and tension in a manner
that is strikingly similar to the behavior of plastic substances under similar
conditions, yet the manner in Avhich it yields is decidedly different. The
flow of liquids and of viscous substances is accounted for by the movement
of adjacent molecules past each other, in any direction ; in ice, motion in
response to pressure or tension takes place along gliding planes which
have a definite relation to the optical axis of the crystals.

The movements observed in ice under pressure is not, therefore, true
plasticity, but, as pointed out by McConnel, is identical in nature with
the displacements along planes observed in rock salt, Iceland spar, and
other certain substances when subjected to pressure. For this peculiar
"plasticity" no definite name has been proposed.^

1 "On the Plasticity of Glaciers and Other Ice," Proc. Roy. Soc, London, vol. 44, 1888,
pp. 331-307. Also, J. C. McConnel, "On the Plasticity of an Ice Crystal," Ibid., vol. 48,
1890, pp. 256-260 ; vol. 49, 1891, pp. 823-343.

2 The experimenta by McConnel and Kidd cited above have recently been repeated by
Dr. O. Miigge, and are described by Cl'aniberliu, iu the Journal of Geology, vol. 3, 181»&,
pp. 905, 060, as follows :

" Prisms were cut from carefully formed ice in various directions to the principal crys-
tallographic axis, i.e. the optic axis of the crystal, particularly in directions parallel and
transverse to it. These were tested by placing their ends on supports, and weighting them in
the center. In testing the transverse prisms, the optic axis was firt^t placed in a vertical posi-

168

GLACIERS OP NORTH AMERICA.

Experiments by Tyiidall on the moulding of ice into various shapes,
by pressure applied with comparative rapidity, will be referred to in
advance in connection with the consideration of another property of ice,
namely, revelation.

The manner in which glaciiu ice moulds itself to the inequalities of
the rocks over which it flows, so as, in many instances, to polish and striate
the bottoms and sides of narrow trenches, and even the under surfaces of
projecting ledges, is undeniable evidence that it behaves as a plastic body.
One of the objections urged against the idea that ice is plastic is that
although it yields to pressure, it is supposed not to yield to tension, and
hence lacks one of the properties of a ulastic substance. The formation
of cracks in glaciei's is frequently cited as proof that ice breaks under t(;n-
sion. This conclusion was held by Tyndall, who apparently demonstrated
by delicate experiments that ice would not yield to tension except by frac-
ture. More recent experiments by McConnel and Kidd, already cited,
have shown, however, that ice does stretch under tension when slowly
applieu. The widening of crevasses, frequently to be observed both in neve

tion. The prisms sagged, and their ends were drawn inward. Optical examination showed
that tlie optic axis remained normal to the bent surface. Subsequent observations on surfaces
fractured for tlie purpose showed striation and other indications that plates of the crystal
parallel to the basal plane had sheared upon one another.

" When similar prisms were placed so i,hat these gliding planes stood on edge, no
appreciable results followed, even though greater weights and longer timos were employed.

" When prisms cut parallel to the principal axis were tested, the gliding planes being
transverse to the prism, the weight sunk sharply into the upper face of the prism and a corre-
sponding protrusion apjieared below. As the process continued, the protrusion below kept
closely parallel to the indentation above, both widening somewhat until a section of the prism
had been pushed entirely out. Optical examination showed that the optic axis remained par-
allel to itself throughout. The block remained transparent and free from fracture. The
weight appeared to have simply slipped the plates over their neighbors, carrying the adjacent
ones forward with them to some extent by dragging, but not visibly affecting the more
remote ones.

" If the prism be made of square cards and placed on its side, and a transverse force
applied, the result will illustrate the apparent metliod of movement within the ice crystal in
this last case. If such a prism be pressed at right angles to the cards, it will illustrate the
bending of the first case, and if the cards be placed on edge, they will illustrate the effectual
resistance to deformation of the first case. Variations of temperature through 10° were not
found to produce notable differences of result.

" Not to mention other significant points, the investigation seems to warrant the impor-
tant conclusion that ice crystals yield to deforming forces by the sliding or shearing of the
crystalline layers at right angles to the principal axis. No analogy to the motion of a viscous
fluid appeared. Dr. MUgge had previously found a similar method of deformation in other
minerals, including gypsum, stilbite, and vivianite. In respect to its mode of internal motion,
ice is therefore to be classed with these minerals, rather than bodies properly called
viscous."

HOW AND WHY GLACIERS MOVE.

169

regions and in the ice of the lower portions of glaciers, also snstains the
same conclusion As in the case of the compression of ice, its ability to
stretch under tension is lowered by a decrease of temperature.

Without attempting to review at this time all that has l)een written
concerning the plasticity of ice, it seems safe to conclude, on the strength
of the experiments and observations just cited, as well as many others
which might be given, that ice under pressure slowly applied can ')e made
to flow. That ice is truly plastic^ however, is not sustained by the ex})eri-
ments. The question how much pressure would be required to i)roduce
the flow observed in glaciers still remains. This is a more diflicult
question, and perhaps does not admit of precise determination.

The conclusion reached by Forbes and others, that glaciers flow by
reason of their own weight, that is, ice is sufficiently plastic to shear under
the influence of gravity, has, in the opinion of many physicists, been
demonstrated by the bending of planks of ice when supported at their
extremities. That planks of ice will bend under such conditions has .
been shown by experiments, and also by observing the behavior of blocks
of ice in Arctic regions, which slowly sag when supported at opposite
edges, even when the temperature is continuously far below freezing. In
the bending of a plank of ice under its own weight, there must of neces-
sity be a compression of the material on the upper side and an extension
on the lower side. In other words, the behavior of ice under the influence
of gravity is similar to that of plastic bodies under like conditions. ^

Certain experiments cited by Henry Moseley, ho^^ever, have been
claimed to show that the weight of an ice mass is insufficient to cause it
to change its shape, or shear, in the manner in which many plastic solids
are known to do under the influence of their own weight. But in the
experiments, referred to the difference in the behavior of ice under pres-
sure when slowly applied and when applied with comparative rapidity is,
in the opinion of several competent judges, not sufficiently recognized.
As shown by Moseley, the force necessary to shear a column of ice one
square inch in area of cross section, when applied in the course of 15
or 20 minutes, is about 75 pounds, or 34 times th? computed portion of
gravity available in producing glacial flow, and, therefore, these glaciers
cannot move by reason of their own weight.

Moseley's experiments have been repeated by other physicists, and also,
in part, by the present writer, with essentially the same results, so far as

1 This conclusion is hold by William Mathews and others.
212, 1871, pp. 332-534.

Philosophical Magazine, vol.

170

GLACIEUS OF KOHTH AMEUICA.

the amount of force required to shear ice under the conditions olwerved
in the experinuM : us are concerned. That the conclusions readied from
these exi)erinients can be applied in explaining glacier motion cannot he
so readily accepted.

The experiments made by Moseley have been discussed by J. Ball '
and others, who have shown that the time element is important, and that
there are reasons for doubting if the results reached can be applied in
explanation of the flow of glaciers.

Although the conclusion that ice will flow under the influence of its
own weight may not be established to the satisfaction of all who are inter-
ested in the problem, yet if applied provisionally t > glaciers it is found to
explain many of their movements, and enables one to predict what will
occur under given conditions.

By comparing the movements of glaciers with the movements of pitch
and other similar bodies vmder the influence of gravity, striking analogies
may be obtained. If pitch of the proper cons'stency be placed in a gently
inclined trough, haviug so far as practicable the proportions of a repiesen-
tative glacier-filled valley, it will slowly descend in the same manner that
glaciers move, even though it is extremely brittle at the temperature at
which the experiment is conducted. The flow of the pitch is most rapid
in the central part of the surface of the stream, but decreases gradually in
rate of flow towards the sides and bottom. If two streams of pitch be
made to unite so as to form a trunk stream, representing a compound glr.-
cier, lines of debris on the borders of the tributaries, representing lateral
moraines, will units and forma "medial moraine." Where inequalities
in the bottom of the trough exist, crevasses will appear in the pitch, etc.
In this and other ways the flow of a glacier may be shown to correspond
in a most striking manner with the flow of a plastic substance which is
urged forward solely by the influence of its own weight. Strong as are
the argumei.^s tending to show that glaciers are urged forward in the same
manner that truly plastic suljstances flow under the influence of gravity,
this explanation has not been unanimously accepted.

Many forcible objections to the hypothesis of plasticity have recently
been advanced by T. C. Chamberlin." These objections, however, are
based principally on observations ma^e on the glaciera of Greenland, where
the generally low temperature may be considered as reducing the plasticity

^"On the Cause of the Motion of Glaciers," Philosophical Magazine, vol. 42, 1871,
pp. 81-87.

2 " Recent Glacial Studies in Greenland," Bull. Geol. Soc. Am., vol. 6, 1894, pp. 199-220.

now AND WHY OLAC»EH8 MOVE.

171

of ice to its lowest limit us exliihited in glivcioi*s. Whether this condition,
however, may render the observations Ijss valuahle for determining tlie
existence of phisticity, or make the test more searcliing, might be dift'erently
conclnded.

Chaniberlin states that his ohservations seem to Ije adverse to anytliing
wliicli can be termed viscous fluency. In some instances the surfaces of
glaciei"S were found to rise in the direction of tlic motion of the ice, so
that surface streams flowed backward. Similar changes in surface slope
were observed by the i)resent writer in several instances in tiie neves of
Alaska, and is evidently not exceptional. This phenomenon may, how-
ever, not bo opposed to the hypothesis of plasticity, since the energy wliich
urges forward a given molecule within a glacier is the resultant pressure
of molecules at higher levels. It is principally the surface gradient that
determines the rate of flow. The formation of elevations analogous to
anticlinal folds may be due to the pressure of ice at higher elevations,
acting as a thrust on the edges of layers, the cohesion of which is suthcient
to allow them to bend upward and revei-se the nonnal surface gradient.

The breaking of glacial ice under moderate and slowly acting tension

•

was also observed by Chamberlin, who concludes, as others have done,
that if the ice could stretch even in a slight degree, crevasses would in many
instances be avoided in situations where they are found in abundance.
As the ability of ice *o stretch decreases with temperature, it is to be ex-
l)ected that in the far north the conditions are unfavorable for the stu^^y
of such phenomena. On the whole, the observations thus far made on the
breaking of glacial ice and the formation of crevasses, do not seem to
controvert the results of experiments which show that ice does yield to
slowly applied tension, without rupture. What has been shown by gla-
cialists in many countries, is that the limit to which glacial ice can yield
to tension under certain conditions is frequently exceeded. It was also
noticed that boulders resting on the glaciers in Greenland, or inclosed
within them, showed no tendency to descend through the ice a« heavy
substances descend through viscous bodies. This, as is well known, is
true of bouldei-s carried by glaciera in all countries, and offei-s an objection
to the hypothesis of plasticity that cannot be easily removed.

Everywhere, as stated by Chamberlin, the ice of the Greenland glaciers
appeared to behave as a rigid rather than as a plastic substance. The
rigidity did not prevent contortions and foldiivgs of the laminated ice, but
faults and vein structure also occurred, and there seemed to be no more
occasion to assume plasticity in the one case than in the other.

172

GLAClKUy or NOUTH AMERICA.

Tlie Haine autyio" also remarkn " that there w a theoretical objection to
the aH8umj)tiou of vihcoum Hovvage in the very fact of crystallization itself.
The property of viscous tlovvafjfe rests upon the relative imlifference of u
particle as to its special point of adhesion to its neighbor particles. Tin;
pr()|)crty of crystallization rests upon the strongest preferences respecting,'
such relationshi[)s. Particles of w/ater in their fluid condition lie against
and cohere to each other indiffei'^ntly. When they take on a crystalliru-
form they arrange themselves in specific relationships by the exercise of a
force of the highest order. In the presence of this very forceful disposi-
tion of the particles to retain fixed relationships to each other, it would
seem little less than a contradiction of terms to attribute to them viscous
tlowage. The crystalline body may readily Ix) made to change it« form l)y
the removal of particles from one portion by melting and their attachment
at other points by congelation, but not, I think, by the flowing of crys-
tallized particles over each other while in their crystallized condition."

While some of the objections to the hypothesis of plasticity advanced
by Chamberlin are at present unanswerable, and his general conclusion in
reference to the rigidity of the ice at the north of much weight, yet the
theoretical considerations just quoted would seem to be more than counter-
balanced by the experiments which show that ice composed of many
crystals does yield continuously without fracture both to compression and
tension. If a slab of ice supported at its ends does gradually sag under
the influence of its own weight, simply, and at temperatures that do not
admit of melting and refreezing, it seems unnecessary to argue that on
account of its crystalline structure it is impossible for it so to yield.

The discussion that has been carried on for half a century respecting
the hypothesis of plasticity has been ably advocated on each side, and
some of the arguments against it remain unanswered ; but to-day many able
investigators, and especially many of those who are familiar with glaciers
from actual contact with them, I*; d that it more nearly meets the re-
quired conditions than any other 'hypothesis that has been proposed. That
it is not a complete and sufficient explanation of all the phenomena asso-
ciated with the" flow of gla jers, however, will appear still more forcibly,
I think, from a review of other explanations that have been proposed.

The Hypothesis of Regelation. It is now well known, thanks tf)
Faraday, Tyndall, and others, that when two pieces of ice having a tem-
perature of about 32° F. are brought in contact they freeze together.
This property, now termed regelation, was studied especially by Tyndall,

HOW AND WHV OLACIEKS MOVE.

178

and by him first UHed in attempting to explain plaoier motion. Under the
hy[)Othe.si.s of ivgehition the ice of ghu-ieix is thought to l)e crushed and
tiio fragments reunited hy refreezing after a change of position. "It is
easy, therefore," says TyiuhiU, " to understand how a substance so endowed
can l)e scjueezed through the gorges of the AIjjs, can bend so as to accom-
modate itself to the flexures of the Alpine valleys, and can permit a dif-
ferential motion of its partw without at the same time possessing a single
trace of viscosity."

In illustration of the process of regelation numerous experiments have
been made by placing fragments of ice in moulds of various forms, and
subjecting them to pressure. When thus treated the ice is crushed and
the fragments move past each other so as to take new positions, and are
thus adjusted to the shape of the cavity containing them, but freeze to-
gether in their new positions and form a solid body. In this manner ice
has been made to assume almost any desired t'hape. When the pressure
is slowly applied loide fracture is avoided and the ice changes its shape in
apparently the same manner as many plastic substances would if experi-
mented with in a similar way.

In applying the principle of regelation to account for the flow of
glaciere, it is assumed that the ice is crushed and that the fragments are
made to move past each other and are refrozen in new positions. That
rude fractures may l)e healed by regelation is abundantly attested. When
a glacier passes down a steep descent it is greatly crevassed, but below
such an ice fall the fissures frequently close, their walls freeze together,
and the ice is possibly even more compact and homogeneous than before it
was fractured. The conclusion, however, that the characteristic flow of
glacial ice is accomplished in the same manner, but by incipient fractures,
has been seriously questioned.

In the hypothesis of regelation, as in the hypothesis of plasticity, the
force which causes motion is assumed to be the weight of the ice. Instead
of flowing as a plastic substance, however, the ice is considered as behav-
ing as a brittle substance, under the conditions to which it is subjected,
and as being crushed and having the fragments reunited by freezing after
a change in their relative positions. In all of the experiments that have
been made to illustrate the process of regelation a force greater than the
weight of the ice experimented on has been applied. Much discussion has
been carried on in reference to the regelation of ice once fractured and
having its fragments brought in contact at the proper temperature ; but
little has been said, however, in reference to the manner in which glaciera

174

GLACIERS OF NORTH AMERICA.

might be crushed so as to make regelatiop possible. As has been shown
by Moseley, a pressure of about 75 pounds per square inch is necessary
to shear ice if applied with comparative rapidity. Although it seems
impossible to appl}^ these experiments in a quantitative way in explain-
ing the movement of glaciers, they indicate that certain general con-
clusions may be valid. From the experiments referred to it has been
computed that a column of ice in order to begin to crush at its base
would have to be over 700 feet high. Evidently, then, glacier ice
caniiot be crushed under its own weight unless at least 700 feet thick,
and then the fracturing would be confined to the bottom layer ; we shoukl,
therefore, under the hypothesis of regelation, expect the greatest freedom
of move lent to occur in the basal position of a glacier. Yet, as is well
known, the maximum movement is at the surface. How, then, can the
principle of regelation be applied in explaining the surface flow, especially
of a glacier with a low surface gradient ? Again, regelation takes place at
a temperature of about 32° F., and cannot occur much below that temper-
ature unle'^s the ice is und \t pressure. The rate at which the melting-
point of ice Is lowered by pressure is so small that practically it may be
ignored in this discussion. Besides, the rate of surface flow of a glacier is
greater than the rate below the surface, even in winter, when the tempera-
ture of the ice is frequently far below the point where regelation is possible.
It seems, ' therefore, that the regelation hypothesis fails to meet several
important features of the problem of glacier motion.

The principle of regelation is not to be entirely discarded in seeking
an explanation of the behavior of glaciers, however, as the healiiig of
fractures, as already noticed, may be satisfactorily explained in this
manner. The principle of regelation apparently assists one in under-
standing hvHv the granular snow of neves becomes consolidated under
pressure into compact ice. As a neve becomes deeper and deeper, the
granules of which it is composed, but which originate and increase in
size from other jsauses, are brought in contact at the proper temperature
and freeze together. The granules formed from light, porous snow may
by this process be converted into compact ice.

It will undoubtedly occur to the reader that the question whether a
glacier flows by reason of its plasticity or on account of fracture and rege
lation, could be decided by a study of the intimate structure of the ice of
which it is composed. From a geological point of view glacier ice may l)e
considered as a "rock'" and investigated by petrographical methods. That
is, it may be cut into thin sections and examined by means of the micro-

HOW AND WHY GLACIERS MOVE.

175

scope and polariscope. As already described, glacier ice b .3 a peculiar
grain, wbicb is frequently so pronounced and cbaracteristic tbat even a
small fragment may in many instances be readily distinguished even by
the unaided eye from lake and other ice. If the flow of glaciers is due
to plasticity one would expect that the grain of the ice would exhibit
something of a fibrous structure, similar perhaps in a general way to the
structure of wrought iron, or to the structure of cerkan schistose rocks
which have passed through a plastic condition. Nothing resembling this
structure, however, is revealed in tlie grain of glacier ice. The struc-
ture of a characteristic sample oi glacier ice, when examined by means
of a polariscope, is shown in the accompanying figures,^ one of which

A B

Fig. 10. — Steucture of Glacial Ice. (Afteb Pkeley and Fletcher.)

A two-thirds natural size. Hie section is vertical anil at righ*. angles to the tlirection of flow,
B natural size. The section is vertical and parallel with the direction of flow.

exhibits the appearance of a thin section cut parallel, and the other at
right angles to the direction of flow. Although the grains ir. the section
parallel with the direction of flow are perhaps slightly flattened, nothing
resembling a fibroutj structuie or a marked elongation of the granules is
apparent.

Expeiiments by A. Heim,^ have shown that the peculiar grain of glacier
ice is accurately imitated when ordinary lake ice is crushed and again con-
solidated by regelation. So far as the study of the intimate structure of
glacier ice bears on the explanations of glacier motion already considered,

* These diagrams are copied from a paper on " Tlie Structure of Glacier Ice and its Bearing
upon Glacier Motion," by 11. M. Deeley and Geoi^ Fletcher, Geological Magazine (London),
Decade 4, vol. 2, 1896, pp. 152-102.

i' " On Glaciers," I'hilosophical Ma,gazine, vol. 41, 1871, pp. 485-508. Translated from
Poggendorff's Annulen, Erganzunpband, 1870, pp. .30-63.

176

GLACIERS OF NORTH AMERICA.

it favors the hypothesis of regehxtion rather than that of plasticity. Yet,
the observed uniformity in the size of granules composing glacier ice at
various localities and their gradual increase in size from near the source
of a glacier but below the lower limit of the neve to its extremity, aie not
accounted for on the supposition that continual crushing and refreezing
take place.

The Hypothesis of Expansion and Contraction. — Geologists are
familiar with the fact that talus slopes, a:: the piles of loose rock fragments
at the bases of steep escarpments are termed, experience a slow down-
ward crcep^ due to the alternate expansion and contraction of the frag-
mentg composing them, with changes of temperature assisted by gravity.
In a similar way sheets of lead, as observed by Moseley, will slowly creep
down an inclined surface when exposed to variations of temperature.
Glacier ice is exposed to changes of temperature and subject to similar
variations in volume, but owing to the fact that the same change of tem-
perature will produce greater changes in ice than in rocks or lead, th-^t
owing to its greater coefficient of expansion,^ its movements under the
same fluctuations of temperature will be greater.

It is claimed by the advocates of the hypothesis under review, that in
the case of an alpine glacier, for example, the ice in alternately contract-
ing and expanding will slowly creep down a valley, since movement in
that direction is assisted by gravity and in the opposite direction is opposed
to gravity. The same argument has been applied, also, to continental
glaciers originating on a plain and flowing in all dii*ections froin a
center of accumulation, since on account of the rise of the surface
gradient from the periphery toward the center of the mass, the weight
of ice* acting on any point in the glacier is greater in one direction than
in othei-s.

This hypothesis of alternate dilation and contraction was advanced
by Moseley^ and sustained by strong arguments and suggestive experi-
ments, but has been severely criticised by BalH and others. Among the
objections suggested in reference to it are the following :

1 The coefficient of expansion of ice ia nearly twice that of lead, and more than twice that
of any other solid.

* " On the Motion of a Plate of Metal on an Inclined Plane, when Dilated and Contracted ;
and on the Descent of Glaciers," Philosophical Magazine, fourth Series, vol. 23, 1862, pp.
72-79.

•" On the Cause of the Descent of Glaciers," Philosophical Magazine, Fourth Series, vol.
do, 1870, pp. 1-10.

HOW AND WHY GLACIERS MOVE.

177

A glacier lying in a high-grade mountain valley or flowing from a
center of accumulation on a plain, would, if it experienced changes of
temperature, alternately contract and expand, and these changes in
volume should produce a resultant motion in the direction of least
resistance. The direction of least resistance at nearly all points in a
glacier is upward, hence in general the movements in a glacier result-
ing from contraction and expansion would be in a direction normal to
the surface of the ice.

The changes of temperature which might be expected to cause a
glacier to " creep " are such as affect it below the melting-point of ice, for
if raised above that temperature it will melt. Observations have .ihown
that the internal temperature of glaciers is uniformly 32° F., but extended
measui-ements in this connection, especially in winter, are wanting. We
know, however, that so long as the interstices of ice are occupied by water
the temperature of the mass cannot vary sensibly from that just stated,
the effect of pressure being disregarded ; and as glaciers, at least in tem-
perate latitudes, are as a rule saturated with v/ater in summer, they must
have a uniform temperature at that season of 32° F. In winter the tem-
perature of the air above a glacier may fall far below freezing, and if such
a change should be continued long enough the temperature of the entire
glacier would be correspondingly lowered.

With the above considerations in mind it is evident that under the
" creeping hypothesis " the rate of flow of a glacier should be greater
in winter than in summer, and should also be more rapid by night
than by day. This seems to be a crucial test which reduces the
hypothesis to an absurdity, since we know that glaciers flow more
rapidly in summer than in winter, and that their motion is greater by
day than by night.

If additional evidence of the inadequaviy of the hypothesis of dilatation
id contraction was desired, the slow conductivity of both ice and snow,
dad the manner in which glaciera are invariably blanketed with snow
throughout a large part of the year might be considered. For example,
in neve regions, the loose granular snow is frequently hundreds of feet,
deep, and is not only an exceedingly poor conductor of heat, but, on account
of its open texture, would undergo but slight changes in mass on account
of changes in temperature, since slight movements of the granules would
be taken up by the adjacent interspaces. It does not require accurate
observations to show that in such regions changes of temperature are too
brief to be felt at any considerable depth, and even under the most ex-

178

GLACIERS OF NOllTH AMEUICA.

treme conditions could not cause sufficient change to account for the flow
known to occur in neves. The considerations here suggested will be
again referred to in connection with certain " molecular hypotheses " that
have been proposed to account for glacier flow.

From the considerations offered above it seems evident that the
hypothesis suggested by Moseley cannot be accepted as a final explana-
tion of the flow of glaciera.

It is equally plain, however, that it does contain an element of truth,
since it cannot be denied that ice, like most other substances, does contract
and expand with changes of temperature, or that glaciers are exposed to
cc^xditions which bring sibout such changes. Some fraction of glacier
motion must, therefore, be due to those causes.

The Hypothesis of Liquefaction under Pressure. — The fact that
the freezing-point of water is lowered by pressure, discovered by James
Thompson^ and confirmed by his brother William,^ was at once applied in
explanation of glacier motion.

As stated in the papers just referred to, if ice at 32° F. is subjected
to pressure, pores occupied by liquid water must instantly be formed in
the compressed parts, for the reason that ice cannot exist at the above tem-
perature under a pressure exceeding one atmosphere. If the conditions
permit, the water formed by the melting of the parts under pressure Avill
be forced to where the pressure is less and at once refreeze. The parts
recongealed after being melted must in turn, through the yielding of
other parts, receive pressure from the applied force, thereby to be again
liquefied and to enter again into a similar cycle.

In applying this principle to glaciers it is claimed that the water
formed by liquefaction may in part descend, and on re freezing occupy a
lower position. (It might be asked, however, why the water, if under
pressure, should descend rather than move in any other direction.) A
continuation of this process, it must be admitted, would tend to crowd an
alpine glacier down the valley it occupies, but the amount of movement
thus produced would be small.

In opposition to this hypothesis it is evident that the greatest pressure,
at least in the case of a glacier flowing through an even channel, is at the
bottom, Avhile the surface sustains the pressure of only one atmosphere,

* " On the Plasticity of Ice, as manifested in Glaciers," Roy. Soc, Proc, vol. 8, 1867, pp.
455-468. " On Recent Theories and Experiments regarding Ice at or near its Melting-point,"
Roy. Soc, Proc, vol. 10, 1859, pp. 152-160.

HOW AND WHY GLAGIEHS MOVE.

179

and in the great majority of cases of less than one atmosphere, yet the
maximum flow is always at the surface. Additional weight is given to
this objection when we recall the fact that the flowing motion observed
in glaciers is greatest at the surface even in cold weather ; at such times
the surface ice may reasonably be concluded to have a lower temperature
than the bottom ice, and therefore require a greater amount of pressure
to cause it to liquefy.

It does not seem as if further argument was necessary to show that the
lowering of the melting-point of ice by i)ressure does not furnish a com-
plete and satisfactory explanation of glacier motion ; but that it may play
a part in the phenomena for which an explanation is sought, especially in
the case of excessively thick ice bodies or of glaciera flowing thnugh
irregular channels, cannot be refuted.

The H5T>othesis of Molecular Change. — An ingenious and highly
suggestive hypothesis advanced by James Croll to account for the flow of
glaciers is based, in part, oi> the well-known fact that water in freezing
gives out heat and expands on passing to the solid state ; and conversely,
when ice melts heat is absorbed, and in passing to the liquid state occupies
less space than before the change. The difference in volume between ice
at 32° F. and the water formed from its melting, at the same temperature, is
about one-tenth, that is, the ice occupies one-tenth more space than the water.

Another principle that entere into this hypothesis is that heat above
32° may be transmitted through ice, and yet the ice as a mass remain
solid. This has been demonstrated by T3'ndall and others b}^ placing a
delicate heat-measuring apparatus on one side of a siab of ice and bringing
heat to the opposite side. It may thus be shown that some of the heat
will pass through the ice, but portions of it are retained and produce
changes within the mass. As demonstrated by Tyndall, in producing
" liquid flowers " in ice by p^issing heat through it, a portion of the interior
of the mass of ice may be melted by heat that passes through other
portions which remain solid.

The hypothesis before us assumes that the heat of the sun on reaching
the surface of a glacier is partially expended in melting its surface, and
that a part of the water thus formed is transferred to the ice below and is
refrozen, and that the heat liberated melts other portions, which again re-
freeze, aud so on. The essential feature of the hypothesis is that the heat
which enters the ice directly also leads to molecular changes, which cause
the ice to descend. Molecules of ice are assumed to be melted, and on

180

GLACIERS OF NORTH AMERICA.

refreezing pass Iheir heat to other molecules. But the molecules lique-
fied occupy less space than before melting and change their petition in
response to gravity or pressure, and on refreezing again expand and exert
a force on their confining walls.

In the hope of stating this hypothesis more definitely I will use C roll's
own words : " Let us observe what takes place, say, at the lower end of
the glacier. A molecule A at the lower end, say at its surface, receives
heat from the sun's rays ; it melts and in melting not only loses its shear-
ing force and descend^ by its own weight, but it contracts also. B, imme-
diately above it, is now, so far as ^ is concerned, at liberty to descend, and
will do so the moment that it assumes the liquid state. A by this time
has become solid and again fixed by shearing force, but is not fixed in its
old position, but a little below where it was before. If B has not already
passed into the fluid state in consequence of heat derived from the sun,
the additional supply which it will receive from the solidifying of A will
melt it. The moment that B becomes fluid it will descend till it reaches
A. B then is solidified a little below its former position. The same
process of reasoning is in a similar manner applicable to every molecule of
the glacier. Each molecule of the glacier consequently descends step by
step as it melts and solidifies, and hence the glacier, considered as a mass,
is in a state of constant motion downwards."

The heat that reaches a glacier, as stated by Croll, is (1) from the sun,
either directly or through the medium of the atmosphere, rain, etc. ; (2)
earth-heat from the rocks over which the glacier passes ; and (3) the heat
produced by friction. Of these, it seems to the present writer, account
need oidy be taken of the heat derived from the sun. The earth-heat is
certainly small, and for the present at least can be consideied as having no
practical bearing on the question in hand. The heat of friction, if the
movements of a glacier are caused solely by the molecular changes con-
sidered by Croll, is due to the arrest of motion produced by the energy of
the sun, and to admit it as a source of energy to be used in explaining
glacier movement would be utilizing the same energy twice. That is, if
the sun's heat produces glacial movement, and by the arrest of this move-
ment a part of the energy which caused it is reconverted into heat, which
in its turn causes glacial motion, there is no end to the circle. A glacier
would then be an example of perpetual motion.

The above is confessedly an imperfect statement of the molecular
hypothesis, and it is perhaps unjust to suggest obstacles to its acceptance
without a more complete presentation, but as space will not admit of this,

HOW AND WHY GLACIERS MOVE.

181

ion 111
I exert

I must refer the reader to doll's papers and books for a full exposition of
his case.^

Neglecting the j urely theoretical discussion of the manner in which
the molecules of ice are supposed to be influenced by the passage of heat
through it, since this is a question for physicists, let us, as geographers,
see how the hypothesis before us meets the actual conditions with which
we are familiar from field observations.

Assuming, what must be practically true so far as this hypothesis is
concerned, that all the heat which reaches a glacier comes from the sun, it
follows that the energy requisite to loosen the molecules of the ice and to
allow gravity to act in the manner postulated, can only be transmitted to
the glacier w len a thermometer at its surface at the point where the heat
enters stands above 32° F. The higher the temperature indica .d by such
a thermometer the more rapid would be the ice movement. Also, from
the fact that a large amount of energy is consumed in changing the
molecular condition of ice before it can melt — physicists tell us that the
amount of heat absorbed by ice at 32° F., in changing to water at the same
temperature, is equal to ♦.he amount of heat required to raise the water
thus formed from 32° B'. to 172° — it follows that a thermometer at the
surface of a glacier would have to rise well above 32° F. or remain some-
v/hat above that temperature for a considerable time in order that the ice
might receive the requisite amount of heat to initiate the process described
by the author of the molecular hypothesis.

In attempting to apply this hypothesis, however, we are met at the
' outset with the conclusion, not yet successfully controverted, that the in-
ternal temperature of a glacier is always 32° F. or lower. This conclu-
sion is based on several fiicts, as for example : first, direct observations show
that as nearly as can be determined the internr.i temperature of a glacier
in summer is 32° F. ; second, ice in melting under atmospheric pressure
changes to water with a temperature of 32° F., and a mixture of ice and
water has this temperature ; third, a mass of ice in contact with air below
32° F. will have its temperature lowered.

Turning now to a typical alpine glacier we find that near its source the
temperature of the air in contrast with it is always low. In the Mount
St. Elias region surface melting does not occur at elevations in excess of
about 13,000 feet. Above that elevation the snow is always light and dry.

^ " On the Physical Cause of the Motion of Glaciers." Philosophical Magazine, vol. 38,
1869, pp. 201-200. "Climate and Time," 1876, pp. 1160-1196. Also, "The Great Ice
Age," by James Geilcie, 2d ed., 1877, pp. 21-31.

182

GLACIEUS OF NOUTH AMERICA.

At noon on a cloudless August day, at an elevation of 14,000 feet on the
side of Mount St. Elias, I found the teraperuture of the snow at a depth
of two or three inciies, where the surface was directly exposed to the sun,
to l)e sixteen degrees below freezing. This, it must be remembered, is the
most favorable condition for melting that occui-s throughout the entire
year at the locality referred to. At night, even in summer, the tempera-
ture of the air falls far below freezing. For probably nine months or
more each year the temperature of the snow at the surface of the neves in
the St. Elias region is continuously below the freezing-point. It is im-
possible to see how under these conditions the molecular hypothesis can
be applied, yet it is in regions of the nature referred to that glaciers have
their birth. The snow accumulating on neves must move downward be-
fore trunk glaciers can be formed, but if the flow of the lower portions of
glaciers is to be accounted for by molecular changes the same explanation
should be applicable to ndve regions as well.

In some respects the impressions conveyed by what is stated above will
be incorrect, for the reason that few neves are so circumstanced that melt^
ing does not occur on them during a portion of en h year. I shall endeavor
to show, however, that the other extreme of conditions to which neves are
subjected is no more favorable to the molecular hypothesis. As is well
known, the surfaces of neves for a large part of each year are composed of
light, dry snow. The consolidation of this snow, it would seem, must take
place before a pushing force of the nature postulated by Croll could act
efficiently in producing a flowing rrovement in the mass. Consolidation
cf ndve snow does not occur when the temperature of the air in contact
with it is above the freezing-point, as it is then partially melted and
frequently so completely saturated with water as to be soft and slushy,
and, many times, holds shallow lakes in depressions of its surface. No
one will claim, I fancy, that a mixture of snow and water of such a con-
sistency that one will sink knee-deep into it at every step — a condition
frequently present on the neve of Alaska — is favorable to the passage of
heat through it so as to produce molecular changes in the ice below.

It appears, then, that the surface of a neve, both when below 32° F.,
or when it is open and porous, and when it is exposed to a greater tempera-
ture and becomes saturated with water, is unfavorable for the transmission
of solar energy. Again, the surface of a neve is renewed each winter, and
in many instances by summer storms as well ; and at such times is at 32° F.
or lower ; and when surface melting is in progress the snow is saturated with
water and consequently has a temperature of 32° F., hence it is impossible

HOW AND WHY GLACIERS MOVE.

183

to conceive how a temperature in excess of 32° F. could be transiuittod to
the solid ice beneath so as to give it motion.

Nor are the ditliculties in the way of applying the molecular hypothesis
confined to neve regions. The portion of a glacier that protrudes below
its nevd is blanketed with snov. in winter ; the air in contact with it
is then, also, normally below freezing. In summer the surface of the
ice is frequently covered with a porous, coral-like crust, which is almost
as perfect a non-conductor as dry snow ; and when this crust is in process
of melting it is saturated with water and consequently has a general tem-
perature of 32° F., and will not allow heat in excess of that temperature
to pass. Glaciers are also frequently covered more or less completely
with moraines, which, when over a few inches in thickness, still more
effectually shield the ice beneath from solar energy. When we consider
the nature of the surface preseiited by a glacier from its clear-white, s^ow-
covered neve to its dark and frequently moraine-covered terminus, it is
apparent that the positions where hard, blue ice is exposed to the sky are
relatively few. It may be said in general that clear ice is only exposed
for any considerable time when its surface gradient is sufficient to insure
the quick escape of the Avater formed by superficial melting. Under the
molecular hypothesis, other conditions being the same, motion should be
most rapid where the surface of a glacier is composed of clear ice. So far
as now known observations do not harmonize with this postulate.

Although heat may be transmitted through ice in laboratory experi-
ments and cause melting within its mass, yet the conditions, as shown
above, wlien this can occur in the case of glaciers are so infrequent that
the application of this principle in explanation of glacier motion, even
if we knew the nature of the molecular changes that occur, meets what
seem insuperable difficulties.

The Hypothesis of Granular Change. — Recent observations on the
structure of certain Greenland glaciers by T. C. Chamberlin ^ have led
him to conclude, as previously noted, that they behave as rigid rather than
as plastic bodies. The impression gained was that the ice is thrust for-
ward by an expansive force acting from within rather than pulled by
gravity alone after the manner of plastic substances. In seeking for an
explanation of glacier flow with this idea in mind Chamberlin again di-
rected attention to the changes which occur in the granulation of glacier
ice when traced from its source to the extremity of a glacier, and, as others

1" Recent Glacial Studies in Greenland," Geol. Soc. Am., Bull., vol. 6, 1895, pp. 109-220.

)

1
- \

184

GLACIERS OF NOHTU AMEUICA.

have done, Huggested that the principal cause of movement may lie in the
growth of the granules. Through a process of partial melting and re-
freezing it is assumed that a granule may continually change its shape hy
loss in one part and gain in another, and thus either move itself or permit
motion in a neighbor. To bring about this change the author states that
" every warm day sends down into the glacier a wave of heat energy, sen-
sible or i)otential, and that every night sends after it a wave of reverse
energy. These waves follow each other indefinitely, until by intercurrent
agencies they become vanishing quantities. Each season sends through
the mass a greater and more complex wave. The problem, therefore, in
simplified form postulates a mass of ice granules predisposed to melt at
certain points and to freeze or to promote freezing at others, acted upon
by the ever-present but differential forc*^ of gravity and swept by succes-
sive waves of heat energy competent to cause melting where predisposition
to melting exists and to cause growth by freezing where predisposition to
freezing exists. Out of this it would seem that localized freezing and
thawing, growths and decadences, innumerable and constantly changing,
must result, and with thc/n motion of the granules themselves and of the
common mass."

Although, in fairness to my readers, I must confess that I am unable
to discuss either the molecular hypothesis or the recent modification of it
from the standpoint of the physicist, yet the adverse bearing of certain
facts on these hypotheses and difficulties in the way of applying them
to explain well-known glacial phenomena suggest themselves even to a
layman.

Present knowledge of the physical properties of ice and of water seems
to show that when they are in contact at the same temperature, at least
when not under pressure exceeding one atmosphere, there is no reason to
suppose that there would be a mutual change of condition. That is, so
far as I am aware, there is no reason to suppose that a molecule of water
at 32° and a molecule of ice at the same temperature, placed side by side,
would undergo a mutual interchange of their physical properties, the
water becoming ice and the ice changing to water. But this seems
to be an essential feature, although not stated in these words, of both
the molecular hypothesis and the modified version of it.

Another consideration is that molecular changes postulated cannot take
place in ice that is bslow 32° F. unless pressure is greatly increased. If
pressure is the controlling condition, then the movements supposed to occur
would increase with depth of ice, and the bottom of a glacier should flow

HOW AND WIIV GLACIERS MOVE.

185

more rapidly than its surface. This, we know, is the opposite of what
really does take i)lace.

Chan)berlin speak, of waves of sensible or potential heat energy pass-
ing through a glacier every warm day, but it is to Im) remeniljered that
warm days on the upper portions of glaciei-s, especiall}', are mre ; and, as
already pointed out, the n6v6 of a glacier is constantly blankoted by a
non-conducting layer such as no wave of sensible heat, at least, can
penetrate.

The explanation suggested by Chaml)erlin, like its predecessor, is
based on theoretical deductions which have not l)een proven. Before
claiming that solar energy causes motion in glaciers by the melting
and refreezing of molecules, or by changes in the size and shape of
granules, it would be more consistent to determine if these changes do
occur in ice under the most favorable conditions. But even if it could be
shown that a " wave of heat energy, sensible or potential," could lead to a
change in the form and size of granules, the ssime objections to the trans-
fer of such energy from the surface to the inner positions o^ a glacier,
suggested in reference to Croll's hypothesis, would have to be met.

While it is apparently impossible to demonstrate that the changes in
ice assumed by Croll and Chamberlin do not tako place, it is logical to
wait until sufficient reasons have been advanced to prove that they do
occur even under the most favorable conditions, before making the
assumption the basis of a still more extended hypothesis. At present the
postulates on which the molecular hypothesis and its recent modification
rest, may be said to be in the hands of the physicist If their truth is
ultimately demonstrated, they may be passed on to the geologist and
geographer to be tested as a means of explaining glacial motion.

What seems intended as a modification of the molecular hypothesis
has been proposed by R. M. Deeley ^ and can be studied with profit, but
80 far as I have been able to determine it does not differ materially from
the explanation proposed by Croll.

Conclusion.

From the brief account given above of various hypotheses that have
been advanced to account for the movement^' of glaciers, it will be seen
that no one of them meets all the conditions of the problem. No one ex-
planation has been generally accepted, although the hypothesis of plas-

i"A Theory of Glacial Motion," Philosophical Magazine, vol. 25, 1888, pp. 130-164.

186

OLACIEKH UF NORTH AMEUICA.

ticity i)rol)iil)ly has more sidhereiitH than any other. From what hiw l)eeii
Htatetl, however, I think it will appear that several of the explanations
offered are hased on one or more well-e.stablinhed laws and furnish an
explanation of some phase of glacial motion. Even the earliest and lonu.
since abandoned hypothesis of Charpentier, which iwsumes that glaciers
slide as rigid bodies over their betls, contains, as we have seen, an element
of truth. If this can Ik; said of the crudest of all the exj)lanation.s
advanced, the later and more elaborate hypotheses should certainly not
be discarded without careful scrutiny in order to obtain from tli jni all the
assistance ia arriving at a linal theory that is possible. To the discredit
of men of science, it must be acknowledged, that in discussing the problem
of glacier motion, the practice has too frecjue'^^'y i)revailed of rejecting all
previous hypotheses in order to make room for some newer idea. The
attitude of scientific men in this connection has freciuently been that of
an advocate pleading for his client, rather than a judicial balancing of
evidence.

An Eclectic HMiotlicsis. — The review just attempted leads to at least
one conclusion which seems well founded. That is, the phenomena to be
accounted for are complex, and no single law governing the behav of ice
can be made to ex^^lain all phases of glacier motion.

The principal laws and the leading physical properties of ice which are
c neerned in modifying the form of glaciers at one time or another, or at
on«^ locality or another, may be briefly enumerated as follows :

1. Gravity is ever present and tends continually to change the form
of a glacier. This fundaraentil fact is recognized in every hypothesis that
has been advanced.

2. Ice, although brittle under a force quickly applied, yields con-
tinuously under its own Aveight to both pressure and tension in a dimin-
ishing ratio from 32° F. to lower temperatures.

3. Fragments of ice when brought in contact at or near a tempera-
ture of 32" F. will freeze together, but without pressure this does not
occur at lower" temperatures.

4. Water expands on freezing, the increase in volume being about
one-tenth. The converae is also true.

5. Water held in fissures or in the interetices of glaciers exei-ts a
hydraulic pressure, and ol^eys the laws governing capillary attraction.

6. Ice like other solids expands and contracts with changes of
temperature.

HOW AND WHY OLACIEU8 MOVE.

187

7. Heat can be made to piws tlirough ice, as shown by Tyndall, and
portions of the ice may Iw melted by heat that has pauiied tluuugh other
portions without producing visible clianges.

8. The melting-point of ice is hiwered by pressure.

9. A mixture of ice and water under a pressure not exceeding one
atmospliere lias a temperature of 32° F.

10. Ice (.'1 melting absorlw heat. Water on freezing gives out heat.

11. The tenjperature of ice is raised by compression and lowered by
tension.

Other laws may l)e added to this list, but at present those enumemted
seem to be the princi{)al ones that can be applied in solving the question
of the causes of glacier motion.

The phenomena exhibited by glaciers for which explanation is sought
may also be briefly enumerated :

1. Glaciei-s exhibit a v/ell-defined flowing movement, analogous to
the flow of plastic substances.

2. The flow of a glacier, best illustrated by one of the alpine type,
is greatest in the center and at the surface, and decreases toward the sides
and bottom. That is, it is analogous t< i he flow of a river.

3. The flow is greater in summer than in winter, and greater by day
than by night. That is, it varies in harmony with changes in ptmospheric
temperature, and is greatest when the temperature is highest. More than
this, observations have shown that changes in the rate of flow respond
with considerable promptness to changes of temperature.

4. The movements of any given point in a glacier are not uniform in
any one direction, but vary from hour to hour. In the case of an alpine
glacier so far as has been observed, the algebraic sum of the movements
by day are in the direction of descent, while at night there may be a
resultant displacement toward the mountain from which the glacier flows.

5. Motion occui's both in neve regions and in the glacier proper, and
so far as known is of the same nature in each instance ; but more extended
studies la this connection are desired.

6. The mean rate at which a glacier flows is not the same in different
portions of its course. That is, for example, the avertige rate of move-
ment of all points in a given cross section may vary widely from a similar
average in another cross section.

7. When the grade of a valley through which a glacier flows changes
abruptly, or when its bottom or sides are markedly irregular, the ice
becomes broken and crevassed. Tension is also produced under other

188

GLACIERS OF NORTH AMERICA.

conditions, as when a glacier expands on a plain, and rissures are again
formed.

3. Glacial ice alwunds in fissures and interstices which are usually
filled witli water. Near the surface the water held in Ihis manner fre-
quently freezes at night. The effect of winter temperatures must be felt
to a still greater cle})th, but how deep has not been determined. Water
flows from beneath the extremity of nearly eveiy alpine glacier, even in
winter, and to a great extent represents the drainage of the ice. Evidently
the fall of temperature in winter is not sufficient, or not long enough con-
tinued, to congeal all the water that enters the ice during the summer season.

9. Glacial ice is granular. Nev6 snow is also granular. As shown
by Heini, however, the granules of the n6v6 are distinct and of a different
nature from the granules of glacier ice. In the glacier proper the granules
increiise in size from near the neve to its extremity. In restricted areas
the granules are of approximately the same size, large and small grains not
being intermingled.

10. When glacial ice is broiven, as when crevasses are formed, and the
fragments brought in contact, they refreeze.

11. The rocks over which glaciera move become worn and striated.
Hard nodules in glaciated rocks are frequently left in relief. " Chatter
marks," semi-lunar cracks, etc., also occur on surfaces but recently aban-
doned by a receding glacier.

12. Rock basins but recently vacated by glacier ice are smoothed and
striated within, showing that debris-charged ice descended into them i=o
as to wear their surfaces.

13. Debris contained in a glacier tends to decrease its rate of flow.
If we conceive of a glacier compound of clear ice moving at a given rate
and introduce debris — earth, sand, stones, boulders, etc. — into it, with-
out altering other conditions, the effect will be to decrease the rate of
flow, since rigid substances are added to one having properties that are
at lesist analogous to those of a plastic solid. If we gradually increase
the percentage of debris, the mass will become less and less mobile, and
finally acquire such rigidity that under the conditions normally influen-
cing the movements of glaciers it will cease to flow. If the debris, instead
of being uniformly commingled with the ice, is introduced irregularly,
local changes in the rate of flow and even local stagnation will result.^

1 The influence of debris on the flow of glaciers, based on the assumption that ice is plastic
and when in sufficiently large inass'^s will flow under the influence of its own weight, has been
discussed by the author in The Journal of Geology [Chicago], vol. 3, 1896, pp. 823-832.

HOW AND WHY GLACIEKS MOVE.

189

This list of facts, bearing more or less directly on the cliaracter of the
movements that take place in glaciers, and thus furnishing data for test-
ing proposed explanations of their movements, might be extended, but I
believe that the most suggestive observations now in hand have been
enumeiated.

By codifying the Ipavs governing the behavior of ice under various
conditions, and grouping the phenomena related more or less directly with
glacial flow, in the manner just attempted, it will appear, I think, that
the mo^ jments of glacial ice are more complex than has commonly been
stated, and are due at different times and under different conditions to
diff3rent agencies, or to the interaction of various agencies.

Of the forces to which glaciei-s are exposed which tend to change
their shapes, gravity is the only one that acts continually and always in
the same direction. The fact that ice, as shown by careful experiments,
will change its shape under the influence of its own weight at all temper-
atures from a maximum rate at 32° F. as far below as tests have been
carried, and yields continuously to tension as well as to pressure, is strong
evidence favoring the assumption that glaciers descend or flow in a
manner analogous to the flow of plastic bodies. Supplementing this
cause of glacier motion, although apparently in most instances of minor
importance, is the hydrostatic pressure of water enclosed in glacial ice ;
dilatation of water in freezing in fissures ; expansion and contraction of
the ice with changes of temperature ; melting and refreezing, due to
changes in pressure ; regelation ; and, less clearly, molecular changes
caused by the transmission of heat, and the melting, refreezing, and
growth of granules.

The authors of this eclectic hypothesis may be considered to l)e De
Saussure, Charpentier, Agassiz, Forbes, Rendu, Guyot, Tyndall, Thompson,
Croll, Geikie, Heim, Helmholtz, Moseley, McConnel, Chan^berlin, and in
fact all physicists and glacialists who either directly or indirectly have
contributed to the study of glacial dynamics. More than this, the study
of the physical properties of ice and the application of principles already
known or to be discovered in explanation of glacier movements, is not
yet completed. To the list of distinguished names given above, as the
authors of the "eclectic hypothesis," are to be added the names of those
who in the future make contributions to our knowledge of the properties
of ice and of its behavior under various conditions. The new facts and
new principles discovered are to be included in this hypothesis, which
will thus continue to be an illustration of the evolution of ideas.

CHAPTER X.

THE LIFE HISTORY OP A GLACIER.

Glaciers, like streams and lakes, valleys and mountains, have their
periods of youth, adolescence, maturity, and old age, leading to extinction.
Like the snows of winter they come and go in obedience to unseen forces.
Their growth and decline may embrace thousands and even tens of
thousands of years, but even the longest-lived witness but a portion of
the changes in topographical development to which they lend their aid.
The study of existing ice bodies leads backward step by step to the far
greater ice sheets of the glacial epoch. Although the causes that pro-
duced vast continental glaciei-s in comparatively recent geological times
are not well undei-stood, and have been a fruitful source of controversy,
yet when one has in mind the life history of a single existing glacier, it
becomes evident that former periods of extensive glaciation were but
greater steps in the same direction. Methods of study are thus indicated,
and suggestions obtained for attacking unsolved problems in the history
of the earth.

As a beginning in this broad field of exploration, let us endeavor to
obtain a graphic idea of the changes made manifest in the birth, growth,
decline, and death of a single alpine glacier.

The snow line — the lowest limit of perennial snow — may be said to
have its position determined by the intersection of the earth's surface with
an invisible, hollow spheroid of temperature. This invisible spheroid
may for present purposes be f tncied to pass through all points having a
mean annual temperature of 32° F. In the tropics it is some 18,000
feet above the sea, but decreases in elevation toward either pole. In
high latitudes, it may pass below the earth's surface. Its size and form
change in obedience to many far-reaching and frequently antagonistic
agencies, and is never the same for two consecutive years or for any
two terms of years that may be selected. It is modified from within
by changes in the inherent heat of the earth, in movements producing
elevations and depressions, in the distribution of land and water, in the
direction and character of ocean currents, in the movements of the atmos-
phere, in the distribution of vegetation, in topographic relief, and in other

THE LIFE HISTORY OF A GLACIER.

191

ways. It is modified from without, principally by annual and secular
changes in the amount of heat that reaches the earth from the sun due to
changes in the position of the earth, the inclination of the earth's axis,
and perhaps other causes.

When one endeavors to marshal in fancy the interaction of the various
conditions on which the fluctuations of the snow line depend, the wonderful
complexity of glacial problems is suggested. The difficulties to be over-
come are still farther increased when one recalls the fact that while
glaciers do not originate when the mean ainiual temperature is above 32°,
they may not form when that limit is reached, unless still other conditions,
as an abundance of snow, alternations of warm and cold seasons, etc., are
fulfilled.

Could we tint the ever-changing surface of the spheroid of 32° as the
student who uses the microscope sometimes tints the walls of the cells he
examines, and view the earth from a distance, its pulsations in obedience
to the many forces on which its size and form depend would be manifest.
Under those conditions, were time allowed, the various steps in the
gathering of perennial snows, the birth and growth of glaciers, and the
coming and going of geological winters could be followed.

This fancied view of the working of a single part of the complicate
machinery we term climate, is not intended to lead to a discussion of the
ultimate causes of glacial conditions, but merely to invite the reader to
cut loose from ideas of days and years, and view the growth and decline of
a glacier which numbers centuries in its life-span.

The histories of the three main class ; of glaciers usually recognized are
not the same but have many features in common. Individual examples
of each class require such a length of time tu i un their appointed coui-ses,
that but a faint idea of the changes they undergo can be gained from the
study of a single example, even if one spent an average lil> ame in the
task. But by combining observations, made in various regions, on glaciei-s
that have reached different stages in their development or decline, the
chief episodes in the life history of a typical example may be outlined.
Let us climb to a station on a mountain-side, overlooking a deen valley
that leads from white peaks above to a dark, forest-covered i)lain below,
and v/atch in fancy the birth, growth, and retreat of a single glacier of the
alpine type.

The life of an alpine glacier usually begins when a mountain summit
pierces the splieroid of 32°. Whether this happens on account of
changes in the lithosphere or in the spheroid of temperature, or by

192

GLACIEllS OF NORTH AMERICA.

a mutual adjustment of the two, is beyond our present theme. As
the mountain peak reaches higher and higher above the spheroid of
32°, the mantle of snow drawn about its summit descends lower and
lower. Above the snow line the winter's snow is not completely melted
during the succeeding summer, and accumulates from year to year. If
the mountain was sculptured by streams before the postulated change
occurred, or is irregular for other reasons, the snow will be blown from
the peaks and ridges and accumulate to a great depth in the depressions.
The head of a valley becomes filled in this manner with a broad snow
field, and in summer the mountain seems to be tipped with silver. The
snow toward the bottom of the accumulation becomes consolidated by
pressure. Water formed by surface melting percolates through it and is
frozen. The lower layers are thus changed to ice, and a neve is born.
The sr ice of the snow field is softened and partially melted during daj^s
of sunshine or when warm winds blow over it, and freezes at night or
during storms, and a thin crust of ice is formed. Tliis hard, glittering
layer is buried beneath the next succeeding snowfall, and remains as a
well-defined stratum in the growing ne^'e. In the walls of crevasses, the
tliin sheets of ice formed in this way, as may be learned from a near
inspection, appear as narrow blue bands separating layei*s of snow, perhaps
many feet thick. Dust blown from adjacent peaks and cliffs that rise above
the n^ve, stains its surface. The discolored layer is buried beneath subse-
quent snowfalls, and again accents the stratification of the deposit.

If we could plant a row of signals across the neve at right angles to the
trend of the valley down which its surface inclines, we should find in the
course of a few days, or even in a few liours, if our observations were
sufficiently refined, that there is a slow surface movement, greater in the
central and lower portion and tending down the valley. Could we make
similar measurements in a vertical direction where the surface movement
is greatest, we should find that the maximum flow is below the surface,
and probably near the bottom of the deposit. That the rate of movement
increases with the depth and reaches a maximum near the bottom, is
only an inference from the study of superficial phenomena, and has
never been proven by direct measurements. In the glacier proper
the threads of most rapid flow are known to be at a higher level in
reference to the basement layer than is supposed to be the case in the
neve ; accompanying this apparent change in the position of the line
of greatest movement are important modifications in the behavior of
the flowing body.

THE LIFE HISTORY OF A GLACIER.

193

The surface snow of the n6v6 is carried along by the more rapid move-
ment of the consolidated portion deep below, and great breaks are formed
at the base of the encircling cliffs owing to the surface snow being moved
away from them. These breaks, in which the rocks beneath are frequently
exposed, are conspicuous from a distanea. As we watch the slow growth
of the glacier, we note in* the course of centuries, that the amphitheatre
from which it flows becomes gradually enlarged, its walls at the same time
increasing in steepness. The great crevasses on the upper border of the
i\e\6 are filled each winter, but reopen each spring in about the same
I^laces. Observations at intervals of centuries, however, would show that
their positions do not remain the same, but owing to the waste of the
rocks exposed each summer within them, a slow migration toward the
crest of the mountains takes place, that is, the cliffs recede.

As the neve increases in thickness, the motion of the deeper layei"s be-
comes greater, and at length, in late summer or early autumn, a protrusion
of solid ice is seen extending out from beneath its lower margin. The
flow of the young glacier in some instances is so energetic that the n6xe
field from which it is fed is seemingly in danger of exhaustion. At times,
comparatively insignificant n6ves supply ice bodies that are disproi^ortion-
ately large. This occurrence seems to accompany climatic conditions that
are unfavorable to surface raqlting. Possibly the \\jfcrkings of natural
laws in this connection are better illustrated by young glaciers than by
more aged examples, and more perfect snow drainage is secured than when
the ice stream below becomes congested and is clogged with morainal
material.

The young glacier advances its extremity by reason of the more rapid
rate of flow of the ice near the surface and in the center of the stream.
In this way, what was the expanded margin of the ice foot at any indi-
cated time, becomes covered by the ice thrust forward during the next
period of marked advance. The movement being greatest In summer
and least in winter, there is an annual pulsation of the slowly advancing
extremity. There are, besides, periodic changes of similar character but of
greater magnitude. When the advance of the extremity of the glacier is
rapid, the onward surface flow each summer buries the portion remaining
from the previous summer advance. Debris carried on the surface of the
glacial stream thus becomes transferred to the bottom layer. Moraines
deposited in front of the advancing glacier during one summer become
buried by the advancing terminus during the next succeeding summer,
and are added to the ground moraine. Like results follow also from

194

GLACIERS OF NORTH AMERICA.

similar periodic changes of greater magnitude. Owing to the manner of
its advance, the terminus of a young glacier is steep. The frontal slope
is generally higher and bolder than during old age, when the terminus is
receding, but this is not always the case.

From our fancied station overlooking a valley down which a young
glacier has begun its journey, and where also in fancy centuries are but
as hours, we see other similar streams of ice descending tributary valleys
and entering the main avenue of drainage.

The roar of avalanches, especially after heavy snowfalls, as they plow
their way down the mountain-side, awakens the echoes as if heavy guns
had been discharged. The rushing snow masses carry with them dirt,
stones, and occasionally large rock masses, and assist in the formation of
lateral moraines along the borders of the glaciers. When an interval of
sunshine loosens the icy bands with which the shattered cliffs are bound,
stones break away and join the rubbish piles below. Again, when the
shadows of evening fall on the cliffs and the temperature is lowered below
the freezing-point, additional blocks of stone pried off from the faces of
precipices are shot downward with a shrill, whistling sound, and bury
themselves in the soft snow below or strike with a dull thud on the hard
ice. We can see many localities where the ice and snow adjacent to the
cliffs has been mei^ted back by the heat reflected from the rocks, and a
deep gulf formed, into which stones falling from above are precipitated,
and injected, as it were, into the body of the glaciers. There forbidding
recesses, black with accumulated debris, are filled and buried by subse-
quent snowfalls. The waste from the cliffs is thus at the start sealed
up in the borders of the flowing ice stream. Much of the morainal
material, when it begins its slow, downward journey is thus inclosed in
the snow and ice, or is englacial. It becomes superglacial far down the
glacier, when the matrix melts and the foreign bodies contained in it are
concentrated at the surface.

The ice streams advancing down lateral valleys, each in its youth a
separate and independent glacier, unite on reaching the main channel and
form a single compound stream. The various branches do not lose their
identity and- mingle as do the waters of confluent rivers, but with some
change of form flow on side by side. This is plainly shown by the
behavior of the marginal moraines on the adjacent borders of two glaciers
after they unite. The two lateral streams below their point of union
form a single medial moraine in the central part of the compound stream.
While the lateral moraines are apparently united, they still retain some-

thin

not

side.

amp

mor;

the

man

THE LIFE HISTORY OF A GLACIER.

195

!.;5 !

thing of their individuality. The material of which they are composed is
not at firat commingled, but continues as separate streams, flowing side by
side. If one glacier is fringed with fragments of white quartzite, for ex-
ample, and its neighbor with blocks of black basalt, the compound medial
moraine below their place of union will be white on one side and black on
the other. Such a division of a medial moraine may somet' aes be noted
many miles below the place where two tributaries unite. On highly com-
pound glaciei-s the medial bands sometimes exhibit a score or more of
individual threads.

At the extremity of each of the younger glaciers we have watched
advancing there has been an arch in the ice, from beneath which a stream
of muddy water flowed out. Each glacier is the source of a stream, and
in some instances discharges a swift, roaring torrent having the volume
of a river. These streams pulsate with the change of seasons. Their
volume increases in summer and diminishes in winter. Winter and
summer they are heavily charged with silt and mud, while the streams
with which they unite, lower down the mountain, where there are no
glaciers, are clear except after rains. Evidently the glaciera are wearing
away the rocks over which they move, and the streams flowing beneath
them are carrying away the finer products produced by the ceaseless
grinding. The young glaciers conceal their work, and we must wait until
they grow old and melt away before we can discover what changes are
taking place in the channels through which they flow.

Our glacier now receiving the tribute of many lateral ice streams has
passed from the youthful stage to maturity. It fills the valley at our feet
from side to side, and is prolonged for many miles below the shining snow
fields from beneath which we watched it emerge. The vast river of ice
has a depth of a thousand feet or more and a breadth of perhaps one, two,
or three miles. Its width is less than the united breadth of its many
branches. Its great thickness is due to the lateral compression of the
tributaries that have contributed to its growth.

The distinction is well marked between the clear white n6\6 where the
surface is renewed each year by fresh falls oi snow, and the black and
dirt-staiued ice of the glacier proper, where waste exceeds supply and
previously englacial material is being concentrated at the surface. The
glacier proper, as well as the n6v6, is snow-covered each winter and the
details of its surface blotted out, but with the return of summer the snow
on the lower portion is entirely melted. The fringe of the snow mantle
with which the mountains are covered is withdrawn higher and higher as

'■'il

196

GLACIERS OF NORTH AMERICA.

the warm season advances, until in late summer or early autumn, just
before the fii-st storms of the next succeeding winter begin, it reaches its
maximum elevation. The true limit between the surface of the nev6 and
of the glacier proper is then revealed. The snow line is higher on rock
surfaces than on glaciers, showing that the dark rocks absorb more heat
and melt the snow resting on them more thoroughly than does the
brilliant ice. In onr watch of centuries we note that the snow line
experiences many fluctuations. As the glaciers increase in number and
in size and their ndves broaden, the snow line descends lower and lower,
even though the general climatic conditions remain sensibly the same.
This is on account of the reaction on the atmosphere of the ice bodies
previously formed. The snow and ice-covered mountains chill the winds
blowing over tliem more than formerly, and cause heavier precipitations.
Each storm that sweeps over the white peaks, even in summer, is now
accomi)anied by a fall of snow. Glaciers thus tend to change their
meteo )logical environment in such a way as to favor their own growth.

The trunk glacier in the valley below continues to advance century
after century and increases in thickness, particularly towards its terminus.
In its middle and upper course, and especially in the nevd region, the
depth of the frozen flood is but little greater than during the earlier
centuries of its maturity.

An increase in the thickness of a glacier which flows from a lofty
mountain while due mainly to a decrease in the gradient of the valley it
occupies, is aided also by an increase in the load of debris it carries. Each
of these changes tends to increase the friction of flow, but as the advance of
ice from above is continuous, the lower portion of the glacier, wheie the
current is more sluggish, must increase in depth or in breadth, — or more
precisely in area of cross section, — in order to enable the flood to pass.

Another agency which modifies a glacier's life also increases in power
as the glacier advances, namely, the heat of the atmosphere. The lower
a glacier descends the more rapidly is it melted. The gradient of its sur-
face is thus controlled by two groups of antagonistic agencies. Decrease
in flow causes the ice to increase in thickness, while melting lowers its
surface. Still more complexity is apparent when one remembers that an
increase of temperature is accompanied by an increased rate of flow.
The records left by former alpine glaciers in Alaska show that for
many miles after leaving their nev^s they increase in thickness, but as
the effect of the increasing temperature of the lower region they invaded
was felt, they gradually decreased in thickness and receded.

THE LIFE HISTORY OF A GLACIER.

197

Returning to our iniagiiuiry glacier, we observe that in its onward
march it cari-ies the mouths of lateral valleys. If these are without glaciers,
or if the ice bodies in their upper courses fail to reach the main line of
drainage, an ice dam is formed in the main valley, the drainage in the
lateral valleys is held in check, and lakes appear. The accumulated water
may escape either over the surface of the ice dam, usually at its junction
with the rocky side of the valley ; but more frequently the water disaj>
peara beneath the ice and finds its way downward through sul> or englacial
tunnels. These lakes 0:1 the margin of the glacier are subject to great
fluctuations on account of changes in the icy channels through which they
discharge. Not infrequently they are drained suddenly, and floods occur
in the valley below the end of the glacier that confined them. The
empty basins refill when the outlet becomes again closed by movements
in the dam of ice. Not infrequently their surfaces are whitened with
floating bergs, from which boulders are scattered over the bottom. In
spite of the vicissitudes that beset their lives, however, we learn by watch-
ing their basins as they are successively filled and emptied, tlutt deposits of
sand and clay are formed in them, and under favorable conditions may
even fill the depressions up to the level of the wall of ice which in part
forms their boundaries. Important deposits thus originate, and may
remain as a part of the geological record when the glacier melts and the
lakes along its margins are drained.

In our fancied study of the life of a glacier we see it approach a por-
tion of the valley where the descent is rugged and broken. The yellow
wallers issuing from it are churned into foam as they leap from ledge to
ledge. On reaching the place of steep descent the glacier becomes greatly
broken, and for a time falls in detached masses, forming a veritable ice
cascade. The precipice of rock is heightened by a wall of ice, which has
a serrate crest and is broken into towei-s and pinnacles, separated by blue
crevasses. From time to time a great tower falls with a crash, and sends
a cloud of ice fragments rolling down the valley. The steep descent soon
becomes blocked with fallen fragments. The face of the rocky precipice
is concealed from view, except at its extremities, where it joins the sides
of the valley. The broken and pinnacled ice descending the precipice is
cemented together again at the bottom, and the glacier flows on, with but few
scars caused by its rough passage remaining. At the ice fall the descend-
ing mass impinges with great force on the rocks at the bottom of the slope,
and must there have its erosive power augmented. Rock basins worn
out at such localities will be seen when the glacier retreats. The ddbris

198

GLACIERS OF NORTH AMERICA.

carried on the glacier above where it makes its steep descent is, to a con-
si ;lerab!e extent, engulfed in crevasses, but a portion escapes these pitfalls
and still darkens the surface below the cascade. A part of the stones
that Were engulfed soon returns to the surface, by reason of the melting of
the ice ; but some of them remain for a long time in an englacial or sub-
glacial position. At each sharp descent in the bed of the glacier an ice
cascade appears. When the grade is steep but not precipitous, the ice
is greatly broken and presents the appearance of a rapid rather than a
cascade.

The surface of the glacier throughout its lower course, and especially
at its extremity, is dark with debris. The medial moraines so prominent
in its middle course, and from a distance appearing like winding Mghways
leading from the land of flowers to the land of snow, become less well
defined and less definitely separated one from another. The reason for the
flattening and spreading that the moraines suffer is not far to seek. Owing
to the more ra[)id melting of the clear ice the portions protected by debris
are left in relief. The medial moraines whc e best defined are really roof-
like ridges of ice veneered with dirt and stones. From time to time a
rock breaks away from its insecure position and rolls and slides down the
steep slope to the clear ice below, thus tending to widen the moraine-
covered tract. On gaining a new position the fallen block again protects
the ice beneath and is again left in relief by the melting of the adjacent
surface, and the process is repeated. The falls that the rock masses experi-
ence — and the larger ones receive the roughest treatment — result in
many fractures. The blocks of stone are thus reduced in size and prepared
for future usefulness in the formation of soil. Both medial and lateral
moraines are broadened in this way, and in time lose their stream-like
character, and the general surface of the glacier becomes covered with
debris. This process is assisted also by the appearance at the surface of
stones previously enclosed in the ice, but not associated with well-defined
momines.

The accidents that happen to the blocks forming surface moraines, on
account of the uneqvial melting of the glaciers, are repeated on a smaller
scale by individual blocks of stone large enough to shelter the ice on which
they rest. When the conditions are favorable, such blocks of stone are
raised on pedestals and form glacier tables. These growths on the
glacier, like the flowers that bloom beside it, look toward the sun that gave
them birth, and as they increase in height incline toward his mid-day
position. Finally, they slide from their pedestals and the process is

THE LIFE HISTORY OP A GLACIER.

199

repeated. Other features due to differential melting are alao present, but
belong to the minor tletails of the siirfaue where waste exceeds supply, and
are not conspicuous from a distance.

The glacier, now in its full strength, advances from the extremity of
the valley that sheltered its youth and guided its early life, and invades
the piedmont plain. The low lands are densely forested. Majestic spruce
trees and aged moss-covered hemlocks stand in thick, serrate ranks across
the glacier's path, but are mowed down as easily as the grass before a
scythe. Crushed, broken, and splintered, the trunks are piled in huge
confused heaps and overridden and buried by the slow but resistless march
of the ice. Where the waters flowing from the glacier are abundantly
loaded with sand and gravel, they build alluvial deposits about its margin.
The streams in their passage over these alluvial cones subdivide and send
off distributaries into the forest to the right and left, and the trees are
surrounded and buried by sand and gravel while yet standing. A fringe
of dead trees, in part denuded of their branches, marks the areas wliere
the stream-borne deposits have made recent conquests. Under these con-
ditions the glacier advances over the buried forests, and all vestiges of its
existence are blotted out. Centuries later the still erect trunks may be
revealed.

The rfile that a glacier plays in its full strength when it invades a plain
or enters a broad valley may be said to depend on how well it improved
the opportunities of its youth. If the debris it gathered from the amj)hi-
theatre in which it was cradled and from the cliffs that sheltered its early
course is sufficiently abundant, it retains its stream-like character and
builds protecting embankments along its sides as it advances. If the
lateral moraines are not massive in comparison with the volume of ice, the
glacier expands and forms a semicircular terminus in which a constantly
increasing area of surface is exposed to the sun and rain. Radial cre-
vasses appear in the expanding ice foot and still farther assist in its
destruction.

A ritical point of the life of a glacier has now been reached. Will it
have strength to resist the increased warmth of the region it has invaded
and continue to advance, or must it halt at an intangible boundary, where
the annual r. elting balances the flow of ice from higher regions ?

In our fancied watch we will assume that the glacier is not only unable
to advance against the invisible enemies that beset its progress, but that
a climatic cycle favorable to glacial growth has passed its maximum and
begun to swing in the opposite direction. Some distant cause, possibly

Ilk

'iij

200

OLACIEUS OF NOUTII AMEUICA.

tlu) uplieaval of a iMirrier in the oeeiiri, or the slow j^rowth of a coral reef,
hm deflected an ocean current that formerly bithed the a<ljacent coast, and
the winds fail to hring as much moisture to the mountains lus formerly.
Perhaps the relation of the earth to the sun is undergoing a secular
change, and the mean annual temperature, and the relations of the seasons
are so modified tiiat for thousands of yeara conditions unfavorable to the
existence of perennial snow will gradually 8Ui)plant and crowd out the
favorable conditions. Prolmbly a combination of these and other changes
equally gradual in their effects are at work in modifying the size and
shape of the spheroid of 32°, and the snow line is rising at the rate of a
few feet in a century.

The terminus of the glacier seemingly remains stationary for a time,
but in reality is seldom at the same line for many successive yeara. Minor
climatic changes experienced scores of yeai-s, or perhaps even centuries
previously, at the fountains from which it flows, are transmitted like
pulsations through its length, and its extremity advances or retreats a few
feet in a year or in a score of years. Again, climatic changes may promote
or retard melting in the glacier proper, and lead to less sluggish responses
in the position of its terminus. Halts, advances, and retreats may also be
caused by the concentration of debris in its wasting extremity.

The glacier has now passed its period of strength, and many changes
in its appearance and in its behavior become apparent. The flow of even
the most rapid threads of the current in the central part of the stream is
no longer sufficient to renew the surface each year at its extremity. The
terminus instead of advancing is now slowly retreating. Melting from
the surface of the glacier proper is in . ^ess of the supply of ice from
higher regions, and a general shrinking and lowering of the surface is in
progress. The stones and dirt previously held in the ice become more
rapidly concentrated at the surface. Clear ice, especially in the lower
portions of the glacier proper, is no longer visible except in crevasses.
Vegetation begins to take root on the previously desolate fields of debris.
A fringe of flowers and ferns soon margins the stagnant portions, and
transforms them during the summer season into luxuriant gardens. The
forest, previously swept away as a thing too insignificant to be worthy the
attention of the legions of the ice king, re-advances year by year, and in
time flourishes on the moraines resting on the ice under which relics of
their ancestors lie buried. Animals wander through the forest where
moss and thick undergrowths conceal pitfalls in the ice beneath, and are
entrapped. Man, unattentive to the wonders about him, may tread the

THE LIFE HI8TOUY OF A OLACIEU.

•201

silent aisles of the forest without knowing that a dead glacier lies buried
l»eneath the cari)et of vegetation on which he trea«ls. As the ice slowly
melts from l)eneath the forest-covered moraine, openings are formed, and
lakelets surrounded with rank vegetation give variety to the scene. As
these pools enlarge, the soil and lM)ulders on their hanks ar(> undermined,
and uprooted shrubs and trees fall into them. These relics of the forest,
and the peaty soi'i formed where the dei)rcssions are partially drained,
become buried in morainal debris. Many a puzzling record is thus
preserved which will lead students astray in future centuries.

The forest-covered border of the fringing moraine is separated from
the clear ice by broad areas of desolation, on which scarcely a lichen has
taken root. On these monotonous wastes striking changes are likewise
in progress. Scores and perhaps hundreds of lakes are formed, similar to
those in the forest-covered moraine, but producing more apparent results,
since the debris about them id not covered with a mask of vegetation.
As these walls of ice alx)ut the lakelets melt, tiie stones and dirt on the
adjacent surface are precipitated into them, and accumulate deeply over
their bottom. When the general surface is lowered by melting, these
deeply filled holes are transformed into prominences thickly covered with
earth and stones. The irregular piles assume a jjyramidal form, because
of the displacement and sliding down of the rock masses on their borders.
In time the sites of the basins of muddy water are marked l)y huge pyra-
mids of ice, a hundred feet or more in height but concealed from sight by
a veneer of stones. From our observing station, scores and hundreds
of those monuments are in view. Between them are many lakelets not
yet filled, and others that have been drained of their water but are yet
unsightly de])ressions in which the stones are covered with slimy mud.

While the changes noted near the extremity of the glacier have been
in progress, other signs of old age have appeared far up its couree. The
ice no longer fills the valley as deeply as befoie, but an api)arent settling
of its surface has occurred. The mountain slopes rising above its borders
are either bare or sheathed with debris left stranded as the current sub-
sided. The height of the ice during its maximum is marked on each
side of the valley by an abandoned lateral moraine. This ridge is
frequently a well-defined teixace or shelf on the steep slope. The
border overlooking the valley is higher than the margin adjacent to the
mountain, and forms a ridge composed of boulders and stones of many
sizes and shapes. Between the ridge and the upward slope of the moun-
tain, there is frequently a level-floored space, formed of sand and gravel

202

GLACIEKS OP NORTH AMFRICA.

swept by torrents from the region above. Streams descending lateral
gulliei re deflected by tlie outer ridge, and, should the general grade of
the vali ' be sufficiently gentle, may form lakelets and swamps.

The slope of the abandoned lateral moraines, or their gradient, is
plainly less than the gradient of the surface of the ice still remaining in
the bottom of the trough. Far down the valley, near where it opens out
on the piedmont plain, their elevation may be a thousand feet above the
surface to the stagnant ice, but as one traces them up stream this interval
becomes less and less, until in proximity to the lower border of the mantle
of perennial ynow, the two coincide. This is the reverae of the process
noted during the au vance of the glacier, when the strong current caused
the ice to thicken most rapidly at a distance below the source of supply,
and shows tJiat Summer is invading the realm of Winter.

The highest lateral moraine left stranded as the ice melts, marks the
limit lietween the rugged and angular crags that have been long exposed
to the action of frost and rain, and the surfaces which have been worn
and rounded by flowing ice. Above, the lines in the sculpturing are
more or less vevkcal, in conformity with the direction of flow of the
streams and rilU that made them ; below, the most pronounced elements
in the relief trend in the direction of the major axis of the valley, and
appear to be approximately horizontal.

Most interesting of all the records on the sides of the valley left
exposed by the shrinking of the ice, but scarcely discernible from a distance,
are lines and grooves on the ice-worn surfaces. When the rocks are
hard and fine-grained, their pol'shed surfaces glitter in the sunlight like
burnished granite fresh from the builder's hand. A near view will
generally show, however, that the tools that did the polishing were not
carefully selected. The glaciated surfaces are covered by scorings of
varying character, from light, delicate lines, such as might be traced
with a diamond's point, up to deep grooves and heavy irregular gouges,
geemingly made by huge boulders of hard rock forced along under heavy
pressure. The more even lines, especially, are in parallel series and trend
in the direction of ice movement. Similar markings are also to be found
at the extremity of the glacier wherever its retreat has exposed the hard
rocks over v hich it passed. A close inspection will reveal many localities
where the glacial ice charged with sand and stones rests directly in con-
tact with polished and striated surfaces. The manner in which the
graving tools that made the inscriptions are held in the icy matrix is thus
revealed.

THE LIFE HISTORY OF A GLACIER.

203

As we watch the slowly receding extremity of the glacier, we note
that its rate of retreat is not uniform. At times it remains practically
stationary for many yeai-s, and the debris carried forward on its surface
is concentrated in its extremity. When the glacier again retreats, an
irregular accumulation of boulder, stone, sand, and earth, indiscriminately
commingled, is left as an embankment across the valley. The crest of
the ridge forms a curve concave up stream, and is apt to have its more
gentle slope on the side facing the shrunken glacier. Several' such
crescent-shaped piles may be left as the glacier slowly retires. Many of
these abandoned terminal moraines form dams above which the drainage
from the glacier and from adjacent slopes is retarded, and lakes are
formed. These lakes, like those originating along the sides of the glacier
during its advance, are short-lived. They rise rapidly as the ice with-
draws, and in fact are flooded and begin to overflow long before the
retreat of the ice has allowed them to fully expand. While yet sni.dl,
they are turbid with glacial silt and have a peculiar yellowish green color.
When they reach a large size, their waters are more or less perfectly
clarified, and may appear as a plain of blue in which the majestic moun-
tains are mirrored. Where glacial streams enter, there is always a fringe
of yellow shading off through innumerable tints to the clear blue beyond
and showing that abundant sediments are there being deposited. Unfor-
tunately, as it would seem, various agencies conspire to deface and to
remove these pleasing results of glacial agencies. The lake basins are
rapidly filled with sediment, and the overflowing water cuts deep channels
through the unconsolidated material that holds them in check. For these
reasons, they pass rapidly through their predestined changes, and finally
are completely drained and their bottoms transformed into smiling
meadows. Dark evergreen forests border the even meadows of waving
grass, and flowera beautify their surfaces. The now sluggish streams
meander in many graceful curves between banks that are outlined by
the pink of budding willows in spring and with the gold of aspen leaves
in autumn. Deer and other inhabitants of the region find there a
sheltered retreat. The once frozen solitude is transformed into a park,
more beautiful and richer in delicate charms than man has yet designed.
The plowshare of ice that descended from the mountains broke the flinty
rocks and prepared the land for the harvest.

While watching the transformation from stern winter to smiling
summer in the lower valley, the extremity of the glacier has receded
above that portion of its bed where great crevasses and ice cascades broke

204

GLACIERS OF NORTH AMERICA.

its surface during its descent. At the base of these steep slopes, now
worn and rounded, other lakes are born. Their cradles are hollows in the
solid rock. No moraine piles hold the water in check, but the rims of
their basins are polished and striated ledges. Could we see their bottom,
we would find that they, also, are smoothed and rounded. As the ice
withdraws from the higher portions of its bed the number of rock-enclosed
tarns increases, and fresh charms are added to the diversity and beauty of
the region. In neighboring valleys and adjacent slopes where the rocks
are essentially the same but have not been subjected to glacial action, rock
basins are absent. Evidently their abundance in the abandoned beds of
the retreating glacier is the result of the abrasion that the rocks suffered
from the ice that moved over them. They are plentiful where the descent
is precipitous, and absent at lower levels, where the grade of the ice stream
was gentle. The region where they occur is notably free from moraines
and other glacial deposits ; lower down the valley where they are absent
there are heavy accumulations of debris. That their rarity in the lower
part of the valley is not due to the masking of the hard-rock surfaces by
glacial deposits is shown by their absence from areas where such deposits
are lacking. The regions where the rock basins are most abundant are
regions where abrading and transporting agencies were active ; the lower
portion of the valley where they do not occur are where the glacier did
least work, and where deposition and not erosion was the rule. Where
the glacier was heavily charged with debris it became sluggish and did but
little abrading. In many instances rock-basin lakes are situated at the
bottom of steep inclines, down which the ice descended and pressed with
great force on the rocks where there is an abrupt change to a more gentle
grade. The rock-enclosed lakes are, in general, longer-lived than those
held by moraines, but in time they too become filled with sediment and
are transformed into brilliant gardens of alpine flowers.

Had our glacier advanced boldly into the piedmont plain, possibly
another variety of rock basin would have been excavated, but in the fan-
cied instances before us it is not practicable to include a complete analysis
of glacial action.

The last stages in the decline and death of a glacier are slow and
frequently much prolonged. The blue ice visible below the margin of the
white n6v6 contracts more and more, until during certain seasons, or for a
series of yeara, it is completely concealed by a covering of snow. Fluctua-
tion still occurs, however, and during years, or a succession of years, when
the winter snows are light, or summer melting accelerated, the glacier

THE LIFE HISTORY OF A GLACIER.

205

proper may be seen for a short time in late summer or early autumn. In
its old age the glacier reaches a second childhood in which the character-
istics of its early years again appear. So complete is this similarity in
many instances that it is difficult, if not impossible, for one to decide
whether a miniature glacier sheltered in the encircling arms of a mountain
crest, is the beginning of a new ice extension or the remnant of a glacial
epoch that has nearly passed away. The depth and character of the
amphitheatre in which the snow and ice lie, and the shape and sculptur-
ing of the valley leading from it, may furnish proof of a former period of
intense glaciation. But whether in many instances the glacier that did
the work was completely melted and a new period of ice extension initi-
ated, or vrhether a remnant of the dying glacier still remains, I know of
no test by which to decide.

Throughout the growth and decadence of the glacier we have been
watching, it has been apparent that even the grandest results have been
attained by slow, and as they ordinarily appear to us, imperceptible
changes. More than this, the climatic variations made manifest by the
behavior of a glacier do not go on continuously in one direction for long
periods, but are accomplished by irregular pulsations. There have been
great cycles favoring growth or decline, and within these there have been
minor periods during which the changes in progress were retarded and
even reversed ; but the resultant of several minor periods coincided with
the general change in progress.

It is safe to gay that the main features in the life histories of even the
greatest piedmont and continental glaciers are similar to those presented
by a single ice stream of the alpine type. Even the coming ar^d going of
glacial periods are so far as one can judge in obedience to similar laws.
The records left by Pleistot ne ice sheets show that they underwent many
fluctuations, s* .me of which w ere so pronounced that they are usually con-
sidered as indej ident periods. One of these pulsations embraced a far
greater lapse of me than the entire life history of a glacier such as has
just been traced.

A wonderful \ista is unfolded when one attempts to include in a
single mental picture the transformations that accompany a climatic revo-
lution so vast that a continent became buried beneath thousands of feet of
ice, and on retiring left a soil in which the most advanced civilization
known to history took root. Surely such a theme is worthy of being
interpreted in a great poem, beside which the vision of a Dante or a Milton
would be lacking in interest.

203

GLACIERS OF NORTH AMERICA.

Concluding Note.

In preceding chapters I have attempted to present a review of what
is known concerning the existing glaciers of North America, and have
indicated in many instances where more detailed information in refer-
ence to special regions and to individual glaciers may he found. I have
also ventured to point out in some cases the direction in which new
explorations in this fascinating field can be most profitably undertaken.
In the chapter just concluded an attempt was made to present in one view
an outline of the life history of a single alpine glacier. A continuation
of the studies here begun would naturally lead to a review of the records
left by extinct glaciers, since in this, as in many other departments of
geology and physiography, "the present is the key to the past"; but as
our fireside journey over mountains and across ice fields has been long and
arduous, I will, for the present, part company with the reader here.

For the benefit of the student who may desire to continue the course
of reading to which this book is intended as an introduction, I would
suggest the numerous memoirs on surface geology contained in the annual
reports of the United States Geological Survey and in The Journal of
Geology, published at the University of Chicago.

IIS^DEX.

Abrasion of glaciers, described, 18-21.

Advance glacier, 136.

Advance of Malaspina glacier, 127.

Agassiz, L., Views of, on glacial motion, 144.

Agassiz glacier, 1 10.

Alaska, Ketreat of glaciers in, 150-150.

Glaciers of, 74-129.

Alaskan peninsula. Glaciers of, 108, 109.
Aleutian islands. Glaciers of, 108, 109.
Allen, H. T., Journey of, in Alaska, 105.
Alluvial cones, Malaspina glacier, 125, 126.
Alpine glacier. Term defined, 2.

glaciers of Alaska, 96-104.

Auk glacier, 104.

Baker, Mt., Glaciers of, 69, 70.

Baldwin, S. P., Observations on Muir glacier

by, 82.
Belcher, Sir Edward, Voyage of, 75.
Bell, W. H., Cited on glaciers of Stikine

river, 75.
Bergschrund, Description of, 9.
Bering glaciers, Alaska, Mention of, 96.
Biake, W. P., Cited on glaciers of Stikine

river, 75.
Bowdoin glacier, Eate of fiow of, 144.
Brewer, H. W., Cited on Sierra Nevada

glaciers, 43.
Brainard, O. L., Explorations by, 132.
British Columbia, Retreat of glaciers in, 149.
Bulam glacier, 01.

California, Evidence of retreat of glaciers

in, 148.
Geological survey of, in the High Sierra,

61, 52.

Northern, Glaciers of, 66-62.

Canada, Glaciers of, 71-73.
Cantwell, J. C , Explorations by, 128.
Chaney, L. W., Jr., Cited on glaciers in

Montana, 33.

Chapin, F. H., Cited on glaciers in Colorado,

33.
Chaix hills, Alaska, Lakes near, 118-121.
Cirques, Mention of, 10.
Chamberlin, T. C, Cited on the cause of

glacial motion, 183-185.

Cited on roi k scorings, 21.

Explanation of ^iacial motion by, 170-

172.

Observations by, 132.

Observations by, in Greenland, 142.

Reference to writings of, 135.

"Chinese Wall," Grinnell land, 132.
Climatic changes shown by glaciei-s, 140-159.
Colman, E. T. , Cited on glaciers of Mt. Baker,

69, 70.
Continental glacier. Term defined, 2.
Cordilleran region. Briefly described, 32.
Cowlitz glacier, 64.
Crevasses, Formation of, 7-10.

General description of, 7, 8.

in the glaciers of the High Sierra, 42.

Croll, J., Cited on the flow of glaciers, 179-181.

Reference to works of, 163.

References to the writings of, 181.

Cushing, H- P., References to writings of, 87.

Dall, W. H., Fossils identified by, 127.

Dana, Mt., Height of, and glacier on, 39, 40.

Davidson, George, Cited in reference to gla-
ciers of Mt. Rainier, 62.

Glacier named in honor of, 102-104.

Davidson glacier, Alaska, 102-104.

Mention of, 3.

Davis, W. M., Reference to writings of, 103.

Dawson, G. M. , Cited on retreat of glaciers,
149.

Cited on Vancouver system, 32.

Debris, Influence of, on movements of glaciers,
25-28, 158, 188.

Deeley, R. M., Cited on grain of ice, 175.

208

INDEX.

Deeley, R. M., Reference to writings of, 185.

" Devil's slides," 50.

" DeSaussure's Theory," Brief statement of,

163.
Disrupted gouges. Mention of, 21.
Dilatation hypothesis of glacial motion, 164.
Diller, J. S., Cited on glaciers of Cascade

region, 70.
Cited on glaciers of Mt. Shasta, 56, 60,

61, 62.
Dirt bands on Sierra Nevada glaciers, 43.
Disenchantment bay, Alaska, Glaciers of,

02-96.

Retreat of glaciers of, 151-163.

Drainage of Malaspina glacier, 121-123.
Driftless area, Alaska, 107.

Greenland, 134, 145.

Drumlins, described, 24-28.
Dundas bay, Alaska, Glaciers of, 91.
Dust on glaciers. Mention of, 6.

Eagle glacier, 104.

Eclectic hypothesis of glacial motion, 186-189.
Emmons, S. F., Cited on glaciers of Mt.
Rainier, 63-66.

Fletcher, G., Cited on grain of ice, 175.
Fish on Malaspina glacier, 14.
Forest beneath Muir glacier, 86, 87.
beneath gravel, Malaspina glacier, 125-

126.

on moraines of Malaapina glacier, 117.

Forbes, J. D., Cited on glaciaf motion, 165,

166.
Fossils from margin of Malaspina glacier,

127.

Gardner, T. C, Cited on ice blades, 51.
Geikie, J., Reference to writings of, 135.
Geological Survey of California, Work of, in

the High Sierra, 51, 62.
Gilbert, G. K., Visit of, to Mt. Lyell, 38, 48.
Glacial and ocean records, 120.
Glacier bay, Alaska, Glaciers on west side of,

91, 92.

Retreat of glaciers of, 150, 151.

Glacier garden, Switzerland, 14.
Glacier tables, Account of, 11.

on Parker Creek glacier, California, 44.

Glave, E. J., Glaciers seen by, in Alaska, 105.
Grain of glacial ice, 6, 103, 188.
Granular change in glaciers, 183.

Greely, A. W., Explorations by, 131, 1.32.
Green, W. S., Cited on the glaciers of Selkirk

mountains, Canada, 71, 72.
Greenland, Advance and retreat of glaciers

of, 155, 156.

Glaciers of, 133-159.

region. Glaciers of, 35, 36, 131-159.

Groton, Mafis., Drumlins near, 24, 25.
Guyot glacier, 101, 110.

Ilaenke island, Alaska, View from, 92, 93.
Hague, Arnold, Cited on the glaciers of Mt,

Hood, 68, 69.
Hayes, C. W., Cited on glaciers of Alaska,

76, 105, 106.
C'ted on retreat of Alaskan glaciers,

U3-159.

Journey of, in Alaska, 105.

Healy, M. A., Reference to writings of, 128.
Heim, A., Cited on grain of ice, 175.
Henrietta Nesmith glacier, Grinnell land, 132.
High Sierra, California, Description of, 37, 38.

General characters of, 33, 34.

Hood, Mt., Glaciers of, 67-69. •
Hopkins, W., Investigations by, 163, 164.
Hotlum glacier, 61.
Hubbard glacier, Alaska, Brief account of,

92-94.
Humboldt glacier, Greenland, Brief account

of, 134, 135.
Hutli glacier, Alaska, Reference to, 78.
Hypotheses of glacial motion, 160-189.

Icebergs, Origin of, Discussed, 83-86.
Ice pyramids on Mt. Lyell glacier, 46, 46.
Ice tongues of Sierra Nevada glaciers, 47, 48.
Icy cape, Alaska, Brief account of, 96, 96.
Icy strait. Former extent of ice in, 90.
Illecellewaet glacier. Brief description of, 72.

Johnson, W. D., Observations of, in Califor-
nia, 38, 39.
Juneau glacier, 104.

Kane, Cited on Humboldt glacier, 135, 1.36.
Kautz, A. v., Ascent of Mt. Rainier by, 62.
Kidd, D. A., Experiments by, 167.
King, C, Cited, 52.

Cited on glaciers of Mt. Shasta, 55-58.

Klocke Fr., Observations by, 162. '
Klutlan glacier, 106.
Rr cession of, 163.

INDEX.

209

Koch, K. H., Observations by, 162.
Konvvakiton glacier, GO.
Kotzebue sound. Ice cliffs of, 128.

Lake Cast^iai, Alaska, Brief account of, 121.
Likes, Marginal, of Malaspina glacier, 118-

121.

on Malaspina glacier, 115, 11(5.

Le Conte, J., Cited on " ice blades " of Sierra

Nevada glaciers, 42.
Explorations by, in the High Sierra,

,00, 61.
Lemon Creek glacier, 104.
Lenticular hills, see Drumlins.
Libbey , Jr. , W. , Cited on Alaskan glaciers, 76.
Life history of a glacier, 189-205.
Lockwood, Cited on glaciers of N. Greenland,

138.

Explorations by, 132.

Loess, Mention of, 16.

Logan, Mt., Height of, 74.

Lyell, Mt., California, Glaciers on, 40, 41.

Height of, 40.

Lynn canal, Alaska, Glaciers of, 101-104.
lletreat of glaciers on, 150.

Malaspina glacier. Description of, 109-127.

Mention of, 3.

Mention of tunnels in, 16.

Moraines on, 12.

Recession of, 151, 162.

Malaspina's expedition, Reference to, 92.
Mammillary hills, see Drumlins.
Marginal lakes of Malaspina glacier, 118-121.
Mathews, W., Views on glacial motion, 169.
McConnel, J. C, Experiments by, 167.
McConnel, R. G., Cited on retreat of glaciers,

149.
McClure, Mt., California, Height of, 40.
Mexico, Height of peaks in, 33.
Mer de Glace, A type of alpine glaciers, 1.
Mer de Glace Agassiz, Grinnell land, 132.
Miles glacier. Recession of, 153.
Molecular motion in glaciers, 179-183.
Moraines, Characteristics of, 12.

decribed, 22-24.

Ideal sketch of, 7.

of Malaspina glacier, 113-118.

of Sierra Nevada glaciers, 46.

Varieties of, 6, 7.

Moseley, H., Cited on movements of glaciers,

176.

Moseley, H., Experiments by, 169.
Movements of glaciers. Explanations of, 160-

189.
Mt. Dana glacier, Description of, 35-40.
Mt. Lyell glacier. Description of, 40, 41.
MUgge, O., Experiments by, 167, 168.
Mulr, John, Cited on Alaskan glaciers, 76.

Cited on glaciers of Glacier bay, 91.

Discovery of Muir glacier by, 80.

Explorations of, in the High Sierra,

49, 50.
Muir glacier, Alaska, Description of, 80-91.
Recent recession of, 160, 161.

Nansen, F. , Explorations of the inland ice of
Greenland, 140, 141.

Reference to writings of, 135.

N^v^s, Characteristics of, 4, 6.

of glaciers in the Sierra Nevada, Colo-
ratio, 42.

Newberry, J. S., Reference to observation by,
70.

Nisqually glacier, Mt. Rainier, 64.

Nordenskiold, Baron, Explorations by, in
Greenland, 139, 140.

Norrls glacier, Alaska, Reference to, 78.

North America, General distribution of gla-
ciers, 32-36.

Nunatak, Meaning of the term, 133.

Nunatak glacier, Alaska, Brief account of,
92-94.

Nunataks of Greenland, 133.

Oregon, Evidence of retreat of glaciers in,

149.
Osars, described, 28, 29.

of Malaspina glacier, 123-125.

Osier island, Alaska, View from, 95.

Parker Creek glacier, California, Description

of, 41, 43, 44.
Pacific glacier, Alaska, 91.
Peary, R. E., Journeys In Greenland, 140.

Cited on flow of Bowdoin glacier, 144.

Cited on glaciers of Greenland, 135.

Explorations by, 133, 135.

Piedmont glaciers. Description of, 109-127.

Term defined, 2.

Plasticity hypothesis of glacial motion, 166.
Pleistocene glaciers of the Sierra Nevada,

62-64.
Pot-holes, Origin of, 14.

210

INDEX.

Rainier, Mt., Washington, Glaciers of, 62-67.

Recent ascents of, 67.

Recession of Muir glacier, 1)0, ttl.

Red snow of Sierra Nevada glaciers, 48.

Regelation hypothesis of glacial flow, 172-176.

Reid, II. F., Cited on Alaskan glaciers, 76.

Cited on origin of icebergs, 85, 86.

- — Cited on variations of glaciers, 166.

Observations on Muir glacier by, 81.

References to writings of, 87, 01.

Rhone glacier, Mention of, 3.

Richter, Cited on variations of glaciers, 153.

" Ribbon structure " in Sierra Nevada gla-
ciers, 42.

Rink, H., Reference to writings of, 135.

Russell, I. C, Papers on Alaskan glaciers
by, 70.

References to writings of, 87.

Russell glacier, Alaska, 106.

Recession of, 153.

St. Elias, Mt., Height of, 74.
View from, 97, 08.

St. Elias region, Alaska, Retreat of glaciers
of, 151, 152.

Salisbury, R. 1). , Visit of, to Greenland, 145.

Sand cones. Brief account of, 13,

Origin of, 13.

Sand plains, described, 29.

Schwatka, F., Journey of, in Alaska, 105.

S-idiments of glaciers, Definition of term, 28.

Selkirk mountains. Glaciers of, 71, 72.

Selwyn, A. R. C, Cited on Vancouver sys-
tem, 32.

Seton-Karr, H. W., Cited on glaciers of
Alaska, 76.

Seward glacier, Alaska, 98-101.

Shaler, N. S. , Reference to writmgs of, 103.

Sha.sta, Mt., California, Glaciers of, 55-62.

Sierra Nevada, California, Description of gla-
cierstof, 37-54.

Sita-da-ka glacier, Alaska, see Muir glacier.

Sliding hypothesis of glacial motion, 103.

Smith, E. C, Ascent of Mt. Rainier by, 67.

Snow-line, Definition of, 5.

Striae, Direction of, 20.

Striated surfaces not due to glaciers, 19, 20.

Subsoil ice of Alaska, 127-130.

Surface features of glaciers, 11.

Tacoma, Mt., Glaciers of, 63-67.

Taku glacier, Alaska, Description of, 78-80.

Taya inlet, Alaska, Glaciers of, 102.
Thompson, G., Cited on glaciers of Mt.

Shasta, 58-62.
Thompson, J., Experiments by, 178.
Thompson, W., Cited on glacial motion, 178.
Tide-water glaciers. Description of, 77-96.
Till, described, 24.
Topham, H. W., Cited on Alaskan glaciers,

76.
Topographic changes made by glaciers, .30, 31.
Tyndall, J., Cited on glacial motion, 105, 166.

Cited on rej^slation hypothesis, 173.

Tundras of Alaska, Brief account of, 120, 130.
Tunnels in glaciers, Briel account of, 15.
Turner, J. H., Glacier naraod in honor of, 93.
Turner glacier, Alaska, BriDf account of,

02-94.

Unglaciated region in Alaska, 107, 108.

Greenland, 134, 146.

Upham, Warren, Cited on Drumlins, 25.

Cited'on Greenland glaciers, 155.

Reference to writings of, 135.

Vancouver, Observations of, in Icy strait,

90,91.
Vancouver system. Mention of, 32.
Variations in glaciers, IIow to observe, 150.

Tb J Clerical consideration of, 150-160.

Volcanic a ist on Alaskan glaciers, 159.

Washington, Evidence of retreat of glaciers

in, 149.
W'lat is a glacier ? 16-18.
White River glacier, Alaska, 106.

Oregon, 68.

Washinirton, 65.

Whitney, J. I)., Cited on absence of glaciers

in the Sierra Nevada, 51, 52.
Whitney glacier, California, 66.
Whitney, Mt., California, Height of, 37.
Williams, W., Cited on Alaskan glaciers, 76.
Wintun glacier, 60, 62.
Wood, A., Ascent of Mt. Hood by, 67, 08.
Woodward, R. S., Computations by, 130. •
Wright, G. F. , Cited on glaciers of Alaska, 76.
Observations on Muir glacier by, 80,

81.
Reference to writings of, 37, 135.

Yakutat bay. Glaciers of, 03.
Yukon river. Work of ice in, 19.

><^ JAN? 3 l^n3 ^^

ANNOUNCEMENTS

Pm^lPHPIIHIPmWiqpimill

TIm b«tt •ZMnpU in thii country of lh« kind of book* liaat
goographjr n«a<U. — Tht N<dion

THE

LAKES OF NORTH AMERICA

By ISRAEL C. RUSSELL
Professor of Geology in the University of Michigan

8vo. Cloth. xi+ I2S pages- Illustrated.

RECENT advances have made physical geography almost a new
science. Professor Russell here presents a single phase, but one
of great importance. The work is based upon his original
investigations, and is at once thoroughly scientific in substance and
enjoyably popular in style.

As a text-book or reading book for students in geography and
geology the " Lakes of North America" possesses a unique value. Its
interest to the general reader is enhanced by its illustrations and its
happy descriptions of lake scenery.

GLACIERS OF NORTH AMERICA

By ISRAEL C. RUSSELL, Professor of Geology in the University of Michigan
Author of " Lakes of North America "

8vo. Cloth. X + 2IO pages. Iliustrated.

RECENT explorations have shown that North America contains
thousands of glaciers, some of which are not only vastly larger
than any in Europe, but belong to types of ice bodies not there
represented. In the study of the glaciers of North America, and
especially of those in Alaska, Professor Russell has taken an active
part ; and this book not only presents the results of his own explora-
tions but also a condensed and accurate statement of the present status
of glacial investigations. Its popular character and numerous illustrations
will make it of interest to the general reader.

DEPARTMENT OF SPECIAL PUBLICATION

GINN & COMPANY Publishers

GEOGRAPHIC INFLUENCES IN
AMERICAN HISTORY

By ALBERT PERRY BRIGHAM

Professor of Geology in Colgate University, iimo. Cloth. 366 pages.

Illustrated. List price, f 1.15 j mailing price, J!i. 40

IN this new book Professor Brigham has presented
vividly and clearly those physiographic features
of America which have been important in guiding
the unfolding of our industrial and national life. The
arrangement is mainly geographical. Among the
themes receiving special treatment are : The Eastern
Gateway of the United States, the Appalachian Bar-
rier, the Great Lakes and American Commerce, the
Civil War, and Mines and Mountain Life. Closing
chapters deal with the unity and diversity of Ameri-
can life and with physiography as affecting American
destiny.

The book will be found particularly interesting and
valuable to students and teachers of geography and
history, but it will also appeal to the general reader.
The very large number of rare and attractive photo-
graphs and the numerous maps are of importance in
vivifying and explaining the text.

GINN & COMPANY Publishers

DAVIS'S PHYSICAL GEOGRAPHY

»v

WILLIAM MORRIS DAVIS.

Pre/tttor i^ I'hysical Cmojirafhy in Harvard Univtriity,

A'SISTIO BV

WILLIAM IL SNYDER, Master in ScuHct in n'orcitttr Acadtmy.

lamo. Cloth. 438 pagei. Uluttrated. For Introduction, $1.25.

-^HIS textbook presents the leading principles of physical
^ geography in a form adapted to the needs of pupils in
secondary schools. The subject is treated as dealing with "the
physical environment of man." The description of the geo-
graphical controls by which man's ways of living are determined
constitutes the main theme of the book.

TIt" chief headings are: — The Earth as a Globe, the
Atiiiosphere, the Oceans, and the Lands. The greatest amount
of space is given to the subject under the last heading, which is
divided into several chapters, following a method of treatment
developed by the senior author and thoroughly tested in the
Harvard summer courses on physical geography.

Especial care has been taken to adapt the descriptions and
explanations to the capacity of pupils in higher schools. Unusual
technical terms have been excluded almost wholly. Geometrical
and physical explanations have been set apart in an Appendix, in
order that the progress of pupils who have not studied geometry
and physics may not be embarrassed.

Photographs of natural scenery have been freely used for
illustracions of the actual facts of nature. Typical land forms
are shown in dra-vings. Outline maps serve to give definiteness
to nearly every locality mentioned in the text, so that no atlas
need be referred to when using the book.

THE HARVARD GEOGRAPHICAL MODELS.

Designed by William M. Davis, Professor of Physical Geography in
Harvard University. Price, per stt of three, $20.00. Descriptive
circulars sent postpaid on application.

GINN & COMPANY, Publishers.

Boston. New York. Chicage . Atlanta. Dallai.

Davis' Elementary Physical Geography

By WILLIAM MORRIS DAVIS

Author of Davis' "Physical Geography " and Professor of Geology in
" / University

Harvd

lamo. Cioth. vlH + 401 pages + 6 color charts + 16 pages of maps.
Illustrated. Lii>t price, $1.25.

HE " Elementary Phyncal Geography » is a new book
by Professor W. M. Davis, the first authority in the
United States in the field of physical geography. It
retains the characteristic features of the author-
earlier work, " Physical Geography," but is much less difficult
and Is admirably adapted for ure with younger pupils.

The plan of this volume, like that of its predecessor, is to give
the problems of physical geography a rational treatment. The
object of this method is not simply to explain physiographic
facts, but to increase the appreciation of the facts themselves by
associating them with their causes and their consequences. This
relation is not presented merely as an afterthought in a detached
chapter at the end of the book ; it accompanies the presentation
of the facts themselves.

The chfipter on the Atmosphere has been considerably expanded,
and an entirely new chapter has been added on the Distribution
of Plants, Animals, and Man, considered from a physiographic
standpoint. The questions at the end of each chapter, prepared
by an experienced high-school teacher, will be found most useful
in class room work witli this book.

Especially notable sre the illustrations, which include nearly
two hundred splendid woodcuts, five pages of charts in color, and
nineteen full-page half-tone plates from rare photographs.

The Nation, July 3, 1902 : Taken all in all, this seems the most satisfactory
elementary text-book in physical geography yet published. Certainly in its
treatment of the land it has not been surpassed unless, perhaps, by the author's
larger work [ " Physical Geography "].

GINN & COMPANY Publishers

^•■ilpilp*

THE ELEMENTS OF GEOLOGY

By WILLIAM HARMON NORTON

Professor of Geology in Cornell College, Mt. Vernon, Iowa

8vo. Cloth. 461 pages. Illustrated. List price, |! 1.40 ; mailing price, $1.55

THE essentials of the science of geology are treated
with fullness and ample illustration in this text-book
for beginners. By limiting his discussion chiefly to this
continent the author has ueen able to devote a large
amount of space to the principles which he describes. The
following characteristics are important.

1. The outline is exceptionally simple. Under the leading geological
processes are grouped the rock structures and land forms of which
they are the cause.

2. The inductive method is emphasized throughout. Concrete
examples are given large space as the basis of generalizations of the
science. Numerous exercises and problems, many of which are in the
form of diagrams, are designed to train the pupil and to test his
knowledge.

3. The cycle idea is made prominent, and both the records of erosion
and those of sedimentation are given special attention.

4. In historical geology a broad view is affoii' ;d of the development
of the North American continent anu of the evolution of lift upon the
earth. Only the leading types of plants and animals aia mentioned,
and specia' attention is givt n to those which mark the lines of de-ocent
of forms now living.

The book is designed for use in high schools and acad-
emies, and may also be found useful in short elementary
college courses.

GINN & COMPANY Publishers

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