THE GLACIERS
Of the small residual glaciers mentioned in the preceding chapter, I
have found sixty-five in that portion of the range lying between
latitude 36° 30′ and 39°. They occur singly or in small groups on the
north sides of the peaks of the High Sierra, sheltered beneath broad
frosty shadows, in amphitheaters of their own making, where the snow,
shooting down from the surrounding heights in avalanches, is most
abundant. Over two thirds of the entire number lie between latitude 37°
and 38°, and form the highest fountains of the San Joaquin, Merced,
Tuolumne, and Owen’s rivers.
The glaciers of Switzerland, like those of the Sierra, are mere wasting
remnants of mighty ice-floods that once filled the great valleys and
poured into the sea. So, also, are those of Norway, Asia, and South
America. Even the grand continuous mantles of ice that still cover
Greenland, Spitsbergen, Nova Zembla, Franz-Joseph-Land, parts of
Alaska, and the south polar region are shallowing and shrinking. Every
glacier in the world is smaller than it once was. All the world is
growing warmer, or the crop of snow-flowers is diminishing. But in
contemplating the condition of the glaciers of the world, we must bear
in mind while trying to account for the changes going on that the same
sunshine that wastes them builds them. Every glacier records the
expenditure of an enormous amount of sun-heat in lifting the vapor for
the snow of which it is made from the ocean to the mountains, as
Tyndall strikingly shows.
The number of glaciers in the Alps, according to the Schlagintweit
brothers, is 1100, of which 100 may be regarded as primary, and the
total area of ice, snow, and _névé_ is estimated at 1177 square miles,
or an average for each glacier of little more than one square mile. On
the same authority, the average height above sea-level at which they
melt is about 7414 feet. The Grindelwald glacier descends below 4000
feet, and one of the Mont Blanc glaciers reaches nearly as low a point.
One of the largest of the Himalaya glaciers on the head waters of the
Ganges does not, according to Captain Hodgson, descend below 12,914
feet. The largest of the Sierra glaciers on Mount Shasta descends to
within 9500 feet of the level of the sea, which, as far as I have
observed, is the lowest point reached by any glacier within the bounds
of California, the average height of all being not far from 11,000
feet.
The changes that have taken place in the glacial conditions of the
Sierra from the time of greatest extension is well illustrated by the
series of glaciers of every size and form extending along the mountains
of the coast to Alaska. A general exploration of this instructive
region shows that to the north of California, through Oregon and
Washington, groups of active glaciers still exist on all the high
volcanic cones of the Cascade Range,—Mount Pitt, the Three Sisters,
Mounts Jefferson, Hood, St. Helens, Adams, Rainier, Baker, and
others,—some of them of considerable size, though none of them approach
the sea. Of these mountains Rainier, in Washington, is the highest and
iciest. Its dome-like summit, between 14,000 and 15,000 feet high, is
capped with ice, and eight glaciers, seven to twelve miles long,
radiate from it as a center, and form the sources of the principal
streams of the State. The lowest-descending of this fine group flows
through beautiful forests to within 3500 feet of the sea-level, and
sends forth a river laden with glacier mud and sand. On through British
Columbia and southeastern Alaska the broad, sustained mountain-chain,
extending along the coast, is generally glacier-bearing. The upper
branches of nearly all the main cañons and fiords are occupied by
glaciers, which gradually increase in size, and descend lower until the
high region between Mount Fairweather and Mount St. Elias is reached,
where a considerable number discharge into the waters of the ocean.
This is preëminently the ice-land of Alaska and of the entire Pacific
Coast.
[Illustration: MAP OF THE GLACIER COUNTRY]
Northward from here the glaciers gradually diminish in size and
thickness, and melt at higher levels. In Prince William Sound and
Cook’s Inlet many fine glaciers are displayed, pouring from the
surrounding mountains; but to the north of latitude 62° few, if any,
glaciers remain, the ground being mostly low and the snowfall light.
Between latitude 56° and 60° there are probably more than 5000
glaciers, not counting the smallest. Hundreds of the largest size
descend through the forests to the level of the sea, or near it, though
as far as my own observations have reached, after a pretty thorough
examination of the region, not more than twenty-five discharge icebergs
into the sea. All the long high-walled fiords into which these great
glaciers of the first class flow are of course crowded with icebergs of
every conceivable form, which are detached with thundering noise at
intervals of a few minutes from an imposing ice-wall that is thrust
forward into deep water. But these Pacific Coast icebergs are small as
compared with those of Greenland and the Antarctic region, and only a
few of them escape from the intricate system of channels, with which
this portion of the coast is fringed, into the open sea. Nearly all of
them are swashed and drifted by wind and tide back and forth in the
fiords until finally melted by the ocean water, the sunshine, the warm
winds, and the copious rains of summer. Only one glacier on the coast,
observed by Prof. Russell, discharges its bergs directly into the open
sea, at Icy Cape, opposite Mount St. Elias. The southernmost of the
glaciers that reach the sea occupies a narrow, picturesque fiord about
twenty miles to the northwest of the mouth of the Stikeen River, in
latitude 56° 50′. The fiord is called by the natives “Hutli,” or
Thunder Bay, from the noise made by the discharge of the icebergs.
About one degree farther north there are four of these complete
glaciers, discharging at the heads of the long arms of Holkam Bay. At
the head of the Tahkoo Inlet, still farther north, there is one; and at
the head and around the sides of Glacier Bay, trending in a general
northerly direction from Cross Sound in latitude 58° to 59°, there are
seven of these complete glaciers pouring bergs into the bay and its
branches, and keeping up an eternal thundering. The largest of this
group, the Muir, has upward of 200 tributaries, and a width below the
confluence of the main tributaries of about twenty-five miles. Between
the west side of this icy bay and the ocean all the ground, high and
low, excepting the peaks of the Fairweather Range, is covered with a
mantle of ice from 1000 to probably 3000 feet thick, which discharges
by many distinct mouths.
[Illustration: MOUNT RAINIER; NORTH PUYALLUP GLACIER FROM EAGLE CLIFF]
This fragmentary ice-sheet, and the immense glaciers about Mount St.
Elias, together with the multitude of separate river-like glaciers that
load the slopes of the coast mountains, evidently once formed part of a
continuous ice-sheet that flowed over all the region hereabouts, and
only a comparatively short time ago extended as far southward as the
mouth of the Strait of Juan de Fuca, probably farther. All the islands
of the Alexander Archipelago, as well as the headlands and promontories
of the mainland, display telling traces of this great mantle that are
still fresh and unmistakable. They all have the forms of the greatest
strength with reference to the action of a vast rigid press of
oversweeping ice from the north and northwest, and their surfaces have
a smooth, rounded, overrubbed appearance, generally free from angles.
The intricate labyrinth of canals, channels, straits, passages, sounds,
narrows, etc. between the islands, and extending into the mainland, of
course manifest in their forms and trends and general characteristics
the same subordination to the grinding action of universal glaciation
as to their origin, and differ from the islands and banks of the fiords
only in being portions of the pre-glacial margin of the continent more
deeply eroded, and therefore covered by the ocean waters which flowed
into them as the ice was melted out of them. The formation and
extension of fiords in this manner is still going on, and may be
witnessed in many places in Glacier Bay, Yakutat Bay, and adjacent
regions. That the domain of the sea is being extended over the land by
the wearing away of its shores, is well known, but in these icy regions
of Alaska, and even as far south as Vancouver Island, the coast rocks
have been so short a time exposed to wave-action they are but little
wasted as yet. In these regions the extension of the sea effected by
its own action in post-glacial time is scarcely appreciable as compared
with that effected by ice-action.
Traces of the vanished glaciers made during the period of greater
extension abound on the Sierra as far south as latitude 36°. Even the
polished rock surfaces, the most evanescent of glacial records, are
still found in a wonderfully perfect state of preservation on the upper
half of the middle portion of the range, and form the most striking of
all the glacial phenomena. They occur in large irregular patches in the
summit and middle regions, and though they have been subjected to the
action of the weather with its corroding storms for thousands of years,
their mechanical excellence is such that they still reflect the
sunbeams like glass, and attract the attention of every observer. The
attention of the mountaineer is seldom arrested by moraines, however
regular and high they may be, or by cañons, however deep, or by rocks,
however noble in form and sculpture; but he stoops and rubs his hands
admiringly on the shining surfaces and trios hard to account for their
mysterious smoothness. He has seen the snow descending in avalanches,
but concludes this cannot be the work of snow, for he finds it where no
avalanches occur. Nor can water have done it, for he sees this
smoothness glowing on the sides and tops of the highest domes. Only the
winds of all the agents he knows seem capable of flowing in the
directions indicated by the scoring. Indians, usually so little curious
about geological phenomena, have come to me occasionally and asked me,
“What makeum the ground so smooth at Lake Tenaya?” Even horses and dogs
gaze wonderingly at the strange brightness of the ground, and smell the
polished spaces and place their feet cautiously on them when they come
to them for the first time, as if afraid of sinking. The most perfect
of the polished pavements and walls lie at an elevation of from 7000 to
9000 feet above the sea, where the rock is compact silicious granite.
Small dim patches may be found as low as 3000 feet on the driest and
most enduring portions of sheer walls with a southern exposure, and on
compact swelling bosses partially protected from rain by a covering of
large boulders. On the north half of the range the striated and
polished surfaces are less common, not only because this part of the
chain is lower, but because the surface rocks are chiefly porous lavas
subject to comparatively rapid waste. The ancient moraines also, though
well preserved on most of the south half of the range, are nearly
obliterated to the northward, but then material is found scattered and
disintegrated.
A similar blurred condition of the superficial records of glacial
action obtains throughout most of Oregon, Washington, British Columbia,
and Alaska, due in great part to the action of excessive moisture. Even
in southeastern Alaska, where the most extensive glaciers on the
continent are, the more evanescent of the traces of their former
greater extension, though comparatively recent, are more obscure than
those of the ancient California glaciers whore the climate is drier and
the rocks more resisting.
These general views of the glaciers of the Pacific Coast will enable my
readers to see something of the changes that have taken place in
California, and will throw light on the residual glaciers of the High
Sierra.
Prior to the autumn of 1871 the glaciers of the Sierra were unknown. In
October of that year I discovered the Black Mountain Glacier in a
shadowy amphitheater between Black and Rod Mountains, two of the peaks
of the Merced group. This group is the highest portion of a spur that
straggles out from the main axis of the range in the direction of
Yosemite Valley. At the time of this interesting discovery I was
exploring the _névé_ amphitheaters of the group, and tracing the
courses of the ancient glaciers that once poured from its ample
fountains through the Illilouette Basin and the Yosemite Valley, not
expecting to find any active glaciers so far south in the land of
sunshine.
Beginning on the northwestern extremity of the group, I explored the
chief tributary basins in succession, their moraines, roches
moutonnées, and splendid glacier pavements, taking them in regular
succession without any reference to the time consumed in their study.
The monuments of the tributary that poured its ice from between Red and
Black Mountains I found to be the most interesting of them all; and
when I saw its magnificent moraines extending in majestic curves from
the spacious amphitheater between the mountains, I was exhilarated with
the work that lay before me. It was one of the golden days of the
Sierra Indian summer, when the rich sunshine glorifies every landscape
however rocky and cold, and suggests anything rather than glaciers. The
path of the vanished glacier was warm now, and shone in many places as
if washed with silver. The tall pines growing on the moraines stood
transfigured in the glowing light, the poplar groves on the levels of
the basin were masses of orange-yellow, and the late-blooming
goldenrods added gold to gold. Pushing on over my rosy glacial highway,
I passed lake after lake set in solid basins of granite, and many a
thicket and meadow watered by a stream that issues from the
amphitheater and links the lakes together; now wading through plushy
bogs knee-deep in yellow and purple sphagnum; now passing over bare
rock. The main lateral moraines that bounded the view on either hand
are from 100 to nearly 200 feet high, and about as regular as
artificial embankments, and covered with a superb growth of Silver Fir
and Pine. But this garden and forest luxuriance was speedily left
behind. The trees were dwarfed as I ascended; patches of the alpine
bryanthus and cassiope began to appear, and arctic willows pressed into
flat carpets by the winter snow. The lakelets, which a few miles down
the valley were so richly embroidered with flowery meadows, had here,
at an elevation of 10,000 feet, only small brown mats of carex, leaving
bare rocks around more than half their shores. Yet amid this alpine
suppression the Mountain Pine bravely tossed his storm-beaten branches
on the ledges and buttresses of Red Mountain, some specimens being over
100 feet high, and 24 feet in circumference, seemingly as fresh and
vigorous as the giants of the lower zones.
Evening came on just as I got fairly within the portal of the main
amphitheater. It is about a mile wide, and a little less than two miles
long. The crumbling spurs and battlements of Red Mountain bound it on
the north, the somber, rudely sculptured precipices of Black Mountain
on the south, and a hacked, splintery _col_, curving around from
mountain to mountain, shuts it in on the east.
I chose a camping-ground on the brink of one of the lakes where a
thicket of Hemlock Spruce sheltered me from the night wind. Then, after
making a tin-cupful of tea, I sat by my camp-fire reflecting on the
grandeur and significance of the glacial records I had seen. As the
night advanced the mighty rock walls of my mountain mansion seemed to
come nearer, while the starry sky in glorious brightness stretched
across like a ceiling from wall to wall, and fitted closely down into
all the spiky irregularities of the summits. Then, after a long
fireside rest and a glance at my note-book, I cut a few leafy branches
for a bed, and fell into the clear, death-like sleep of the tired
mountaineer.
Early next morning I set out to trace the grand old glacier that had
done so much for the beauty of the Yosemite region back to its farthest
fountains, enjoying the charm that every explorer feels in Nature’s
untrodden wildernesses. The voices of the mountains were still asleep.
The wind scarce stirred the pine-needles. The sun was up, but it was
yet too cold for the birds and the few burrowing animals that dwell
here. Only the stream, cascading from pool to pool, seemed to be wholly
awake. Yet the spirit of the opening day called to action. The sunbeams
came streaming gloriously through the jagged openings of the _col_,
glancing on the burnished pavements and lighting the silvery lakes,
while every sun-touched rock burned white on its edges like melting
iron in a furnace. Passing round the north shore of my camp lake I
followed the central stream past many cascades from lakelet to lakelet.
The scenery became more rigidly arctic, the Dwarf Pines and Hemlocks
disappeared, and the stream was bordered with icicles. As the sun rose
higher rocks were loosened on shattered portions of the cliffs, and
came down in rattling avalanches, echoing wildly from crag to crag.
The main lateral moraines that extend from the jaws of the amphitheater
into the Illilouette Basin are continued in straggling masses along the
walls of the amphitheater, while separate boulders, hundreds of tons in
weight, are left stranded here and there out in the middle of the
channel. Here, also, I observed a series of small terminal moraines
ranged along the south wall of the amphitheater, corresponding in size
and form with the shadows cast by the highest portions. The meaning of
this correspondence between moraines and shadows was afterward made
plain. Tracing the stream back to the last of its chain of lakelets, I
noticed a deposit of fine gray mud on the bottom except where the force
of the entering current had prevented its settling. It looked like the
mud worn from a grindstone, and I at once suspected its glacial origin,
for the stream that was carrying it came gurgling out of the base of a
raw moraine that seemed in process of formation. Not a plant or
weather-stain was visible on its rough, unsettled surface. It is from
60 to over 100 feet high, and plunges forward at an angle of 38°.
Cautiously picking my way, I gained the top of the moraine and was
delighted to see a small but well characterized glacier swooping down
from the gloomy precipices of Black Mountain in a finely graduated
curve to the moraine on which I stood. The compact ice appeared on all
the lower portions of the glacier, though gray with dirt and stones
embedded in it. Farther up the ice disappeared beneath coarse
granulated snow. The surface of the glacier was further characterized
by dirt bands and the outcropping edges of the blue veins, showing the
laminated structure of the ice. The uppermost crevasse, or
“bergschrund,” where the _névé_ was attached to the mountain, was from
12 to 14 feet wide, and was bridged in a few places by the remains of
snow avalanches. Creeping along the edge of the schrund, holding on
with benumbed fingers, I discovered clear sections where the bedded
structure was beautifully revealed. The surface snow, though sprinkled
with stones shot down from the cliffs, was in some places almost pure,
gradually becoming crystalline and changing to whitish porous ice of
different shades of color, and this again changing at a depth of 20 or
30 feet to blue ice, some of the ribbon-like bands of which were nearly
pure, and blended with the paler bands in the most gradual and delicate
manner imaginable. A series of rugged zigzags enabled me to make my way
down into the weird under-world of the crevasse. Its chambered hollows
were hung with a multitude of clustered icicles, amid which pale,
subdued light pulsed and shimmered with indescribable loveliness. Water
dripped and tinkled overhead, and from far below came strange, solemn
murmurings from currents that were feeling their way through veins and
fissures in the dark. The chambers of a glacier are perfectly
enchanting, notwithstanding one feels out of place in their frosty
beauty. I was soon cold in my shirt-sleeves, and the leaning wall
threatened to engulf me; yet it was hard to leave the delicious music
of the water and the lovely light. Coming again to the surface, I
noticed boulders of every size on their journeys to the terminal
moraine—journeys of more than a hundred years, without a single stop,
night or day, winter or summer.
The sun gave birth to a network of sweet-voiced rills that ran
gracefully down the glacier, curling and swirling in their shining
channels, and cutting clear sections through the porous surface-ice
into the solid blue, where the structure of the glacier was beautifully
illustrated.
The series of small terminal moraines which I had observed in the
morning, along the south wall of the amphitheater, correspond in every
way with the moraine of this glacier, and their distribution with
reference to shadows was now understood. When the climatic changes came
on that caused the melting and retreat of the main glacier that filled
the amphitheater, a series of residual glaciers were left in the cliff
shadows, under the protection of which they lingered, until they formed
the moraines we are studying. Then, as the snow became still less
abundant, all of them vanished in succession, except the one just
described; and the cause of its longer life is sufficiently apparent in
the greater area of snow-basin it drains, and its more perfect
protection from wasting sunshine. How much longer this little glacier
will last depends, of course, on the amount of snow it receives from
year to year, as compared with melting waste.
After this discovery, I made excursions over all the High Sierra,
pushing my explorations summer after summer, and discovered that what
at first sight in the distance looked like extensive snow-fields, wore
in great part glaciers, busily at work completing the sculpture of the
summit-peaks so grandly blocked out by their giant predecessors.
On August 21, I set a series of stakes in the Maclure Glacier, near
Mount Lyell, and found its rate of motion to be little more than an
inch a day in the middle, showing a great contrast to the Muir Glacier
in Alaska, which, near the front, flows at a rate of from five to ten
feet in twenty-four hours. Mount Shasta has three glaciers, but Mount
Whitney, although it is the highest mountain in the range, does not now
cherish a single glacier. Small patches of lasting snow and ice occur
on its northern slopes, but they are shallow, and present no well
marked evidence of glacial motion. Its sides, however, are scored and
polished in many places by the action of its ancient glaciers that
flowed east and west as tributaries of the great glaciers that once
filled the valleys of the Kern and Owen’s rivers.