Canadian Alpine Journal/Volume 1/Number 1/Observations of the Yoho Glacier

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4012237Canadian Alpine Journal — Observations of the Yoho Glacier1907Arthur O. Wheeler


OBSERVATIONS OF THE YOHO GLACIER


By A. O. Wheeler

One of the objects of the recently organized Alpine Club of Canada is the study of prominent glaciers of the region, with a view to obtaining information concerning the formation and flow, advance or retreat of those upon which no observations have as yet been made, and of adding to existing information where some little work in this direction has been done. Speaking generally, it is desired to add the Club's mite to scientific knowledge of glacial action by instituting yearly observations of the more prominent and accessible ice-cascades of the Canadian Rockies.

With two noteworthy exceptions, the observations made thus far have been so casual as to be, practically, of no value. The exceptions are: those by George and William S. Vaux,[1] members of the Academy of Natural Sciences of Philadelphia, and by William Hittell Sherzer, Ph.D., of Michigan State College, under the auspices of the Smithsonian Institution of Washington.

Investigations of the Illecillewaet glacier at the summit of the Selkirk range, near Glacier station on the Canadian Pacific railway, were begun by George and William S. Vaux in 1887, when photographs were obtained of the ice-tongue. They were taken up systematically in 1894 and have been continued yearly since then. Other glaciers upon which they have made observations are: the Asulkan glacier in the Selkirks, and the Victoria and Yoho glaciers in the Main range. The results of their labors—and a good deal of it has been hard work—are set forth in a number of monographs written for the proceedings of the Academy of Natural Sciences of Philadelphia and for "Appalachia," the publication of the Appalachian Mountain Club of Boston, and subsequently issued as excerpt copies.

The expedition of Dr. Sherzer was made in 1904, supplemented by additional observations in 1905. He applied his investigations to five glaciers: The Victoria, Wenkchema and Yoho in the Main range, and the Illecillewaet and Asulkan glaciers in the Selkirk range. The account of his surveys and observations is given to the public in a most instructive and splendidly illustrated monograph, reprinted from Smithsonian Miscellaneous Collections (Quarterly issue), Volume 47, Part 4, No. 1567. In it Dr. Sherzer gives a description of the several glaciers, their sources, surroundings, action and general characteristics, and draws most interesting and conclusive deductions from his notes. The theory here advanced that the origin of "Block moraines" is due to seismic disturbance, is valuable in view of the fact that, at the present date, no snowfield or glacier in either range carries a load of rock fragments of sufficient size to form moraines similar to those studied by Dr. Sherzer under that name. The moraines referred to were found at no great distance from the ice-tongues of the Victoria, Wenkchema and Illecillewaet glaciers.

Owing to close proximity of the Club's annual camp for 1906, the Yoho glacier was the first taken up, and the initial work last summer is now set forth:

The triangular elevated area of mountain peaks and ridges bounded on the eastern side by the trough of the Bow and Mistaya rivers, on the western side by the trough of the Amiskwi river. Blaeberry river and Middle Fork of the Saskatchewan river, and on the south by the trough of the Kicking-Horse river and Bath creek, comprises the Waputik mountains along the Bow river, the President range along the Amiskwi river, and a high range of peaks, as yet without specific name, extending into the apex of the triangle. It contains approximately 400 square miles and nearly through its centre lies the line of the Continental watershed, attaining a maximum elevation of 10,731 feet above the sea in Mt. Balfour, situated near the centre of the tract.

The accumulated ice and snow collected in the interior basin, or series of basins, of this mountain area is named on Government maps the "Waputik Snowfield." This snow or icefield—the latter a more appropriate term, for the snow is but a shallow covering—is practically cut in two by Mts. Gordon and Olive and the ridges of which they form a part. The northern and larger part is the one with which we have to do at the present, and, for the sake of convenience, it is here spoken of as the "Wapta icefield." It has an area of approximately from twenty to twenty-five square miles, and is enclosed in a basin surrounded by Mts. Gordon, Olive, Thompson, Baker, Aysha peak, Mts. Collie, Habel and McArthur, Isolated and Yoho peaks, together with their connecting ridges.

In its turn, the icefield is divided into three principal component parts by lateral rock ridges having precipitous escarpments facing westerly and covered on the eastern sides by snow, where it has piled up in great mounds and slopes. The most western section drains to the Yoho valley, which opens southward from the centre of the tract, chiefly by the Habel glacier, the source of Twin Falls creek. There is also an outflow to the north, between Mts. Habel and Collie. The next section drains both north and south, but chiefly to the south, the iceshed lying close to the northern edge. It furnishes the supply for Yoho glacier, the principal source of the stream of that name. Section No. 3 contains the Continental watershed and drains in small part to No. 2, but chiefly to the east by the Bow glaciers, forming the main source of the Bow river, and by Peyto glacier, a source of the North Saskatchewan river. There are a number of minor overflows, but those named are the principal.

Owing to its position, balanced astride of the Continental divide, the Wapta icefield is of exceptional interest. It feeds four good-sized streams. Two lead through mountains and rolling plains to the Atlantic ocean and two, by a wilder and more broken route, through canyons and dense forests to the Pacific: on the north the Blaeberry river, on the south the Kicking-Horse river, both tributaries of the mighty Columbia; and on the east the Bow river, flowing to the Saskatchewan by a devious southern route, and Mistaya river, flowing direct to the Saskatchewan and thus to Hudson's bay.

The Yoho glacier is the largest outflow from the Wapta icefield. It has little length—less than two miles,—breaking almost directly from its neve between the rocky steeps of Mt. Gordon on the east and Yoho peak on the west, the latter separating it from the Habel glacier. On account of the short run be- tween rock-bound sides, the glacier carries a very small amount of debris and is of remarkable purity. For the same reason its moraines are poorly developed. A short distance above the tongue, the ice stream divides and flows around a knob of rock or "nunatak," which it covered at an earlier date and has now almost wholly encircled by a moraine. The eastern arm is small. At the head of this rock outcrop the main flow breaks into a series of beautiful séracs, reaching across the entire channel in chaotic confusion. The rock sides of Yoho peak, show very distinctly the "plucking" or stripping action of the ice when the glacier
MAP OF WAPTA ICEFIELD
MAP OF WAPTA ICEFIELD
THE ICEFALL OF THE YOHO GLACIER
THE ICEFALL OF THE YOHO GLACIER

THE ICEFALL OF THE YOHO GLACIER

Photo, Byron Harmon.

was much larger and far more powerful than at present. The accompanying illustration shows the dividing rock embossment surrounded by moraine and the wildly broken séracs extending across the glacier. The action of the glacier as an irresistible plane, shaving off the mountain side, is well depicted on the left hand.

The main stream of the Yoho river issues from a fine cave which it has hollowed out in the ice-tongue. The front of the forefoot is precipitous, rising sharply about 150 feet. The slope then assumes a more gentle phase, and walking on the ice between the crevasses, which are here longitudinal, is an easy matter.

On the 14th of July, a committee of five members of the Alpine Club left camp with one of the daily parties making the round trip of the Yoho valley. They stopped for the night at Laughing Falls camp and started early next morning for the glacier. On the road they picked up Mr. George and Miss Vaux, who were camped several miles nearer the ice.

Three independent sets of observations were made to establish initial data from which to start a series of annual observations: (1) to obtain rate of flow; (2) to ascertain retreat or advance; (3) to observe the annual change in the ice formation at the snout. For the first, a row of metal plates were fixed in position across the main ice stream. A suitable base line was then carefully measured along the mountain slope on the eastern side, at a height overlooking the ice. While reaching this position, an interesting feature was noticed in a long line of piled-up tree trunks in various stages of decay, parallel to the trend of the glacier. The adjoining slopes have been swept clear of timber by an avalanche, and are now covered by scrub growth and a few small trees, indicating that, at the time of the avalanche, the ice of the glacier was on a level with the tree trunks. It is at the present time several hundred feet distant and many feet below. In his monograph, Dr. Sherzer refers to this feature and states that he measured the oldest living tree he could find growing in the path of the avalanche, and it had only 47 rings of growth.

Six plates, eight inches square and a quarter-inch thick, having on the under side a piece of inch and a quarter pipe, one foot long, to act as an anchor, were now set at approximately regular distances across the width of the glacier, at a place where the surface was slightly undulating, and as nearly as possible at right angles to the flow. At each point where a plate was set a hole was bored in the ice with an augur and the anchor dropped into place. A surveyor's transit was next set at each end of the measured base and angular readings taken on poles placed in the centre of the plates, thus fixing their position accurately with regard to the established base line. The ends of the base line, on prominent boulders embedded in the mountain side, were carefully marked with red paint and a suitable inscription. Similar readings taken from the same base points at any future date will at once indicate the changed position of the plates and, provided there has been no local displacement, will give an accurate estimate of the flow of the surface of the glacier at each point where a plate was set.

The plates and method were the same used by Messrs. George and William S. Vaux for the Illecillewaet glacier. It was now found—and has since been learned that the same experience applied to the Illecillewaet glacier—that the kind of plate used was not a good one; for, returning across the ice later on, it was seen that each plate was raised more than an inch above the surface, owing to the melting of the ice where exposed to the sun, which had not taken place to a similar extent at the bottom of the holes. It is presumed this will continue, day by day, until the plate topples over. Even then, it should remain stationary on the surface, unless struck by a rolling boulder or undermined by a rivulet.

Work was next carried to the moraines in front of the ice-tongue, on the east side of the river. They are of a somewhat nondescript character and represent rather incipient lateral moraines, formed by the ice-nose during its protracted retreat, than perfectly formed terminal moraines. The valley floor is here traversed by rock ribs, grooved and polished by the ice, stretching down it longitudinally. On one of these moraines two, deeply imbedded, boulders were marked with red paint and the distance measured to the nearest ice for future reference. Photographs, also, were taken from the boulders for annual comparison of the changes occurring in the ice front through melting and disintegration.

Mr. George Vaux pointed out the marks placed by Miss Vaux in 1901, which were still quite legible. At that date a line was drawn in red paint down one of the rock ribs referred to, as nearly as possible at right angles to the flow of the most advanced ice. It was now found that the most advanced ice had retreated about seventy-six feet, yielding an annual average retreat of fifteen feet. This, however, would not necessarily represent the retreat for any one year, for the ice may have been stationary or even have advanced a little during the period.

In his notes of the Yoho glacier, Dr. Sherzer writes: "In August, 1901, independent marks were established by Miss Vaux and H. W. DuBois, from the former of which it was found that the ice here has retreated 111 feet in three years, or at an average rate of 37 feet a year. This measurement was made to the glacier itself and not to the detached block which has been the nose. Measured to the block, the distance was 92.1 feet, giving an average of nearly 31 feet a year, with a retreat of 23 feet for the year 1903-4." The measurements now made were to the nearest ice. Mr. Vaux's marks were renewed and the present farthest point of advance marked on the same rock rib, at a distance of seventy-six feet.

On the western side of the stream, a gigantic boulder was found, marked with the legend, "Sr., A, 8|17|'04. To ice 79.4 ft." The marks and measurement were made by Dr. Sherzer in 1904. A measurement now made to the nearest ice gave 79.6 feet, showing that the ice was, practically, in the position it had occupied when the previous measurement was made.

The accompanying map of the tract here referred to as the Wapta icefield is copied from a topographical map of the Yoho valley section of the mountains, now in course of preparation from Government photographic surveys, and is reproduced by permission of Dr. E. Deville, Surveyor-General of Dominion lands.

During the annual camp of the Club for 1907, the above observations will be checked and the changes noted for contribution to a series of records. Observations, also, will be commenced on the Horseshoe glacier at the head of Paradise valley, where the annual camp will be held.

FIELD NOTES OF OBSERVATIONS.

Taken on the Yoho Glacier.

July 15th, 1906.




To Obtain Rate of Flow.

Readings taken on plates set across the ice forefoot of the Yoho Glacier,
from a base on the eastern mountain slopes.

Readings at Sta. A.

Circle Right. Circle Left.
A B A B
on B     = 180°00′ 360°00′ 360°00′ 180°00′
on No. 1 = 102°08′ 282°07′ 282°07′ 102°06′
on No." 2 =  95°41′ 275°40′ 275°40′  95°39′
on No." 3 =  93°45′ 273°44′ 273°44′  93°43′
on No." 4 =  90°54′ 270°54′ 270°53′  90°52′
on No." 5 =  88°58′ 268°58′ 268°57′  88°56′
on No." 6 =  87°46′ 267°46′ 267°65′  87°44′

For Advance or Retreat.

On terminal moraine on east bank of river, rock No. 1, marked:—

"A.C.C., No. 1, July 15, 1906.
Nearest ice 27½ft."

At highest point of moraine, at a distance of 79.3 feet southerly from rock No. 1, took photograph of most advanced ice.

(See Plate)

Rock No. 2, on same moraine, marked:—

"A.C.C., No. 2, July 15th, 1906, 33.6 ft."

Took photograph of front of glacier from this rock.

Mr. George Vaux renewed the marks placed by Miss Vaux in August, 1901.

The marks were:—"V|X. Aug., 1901."

These were placed an west face of a rib of rock on the east side of the river, as nearly as possible at right angles to the line of the most advanced ice.

Took photograph of front of glacier at a point along rock rib, 6½ feet nearer to the ice. Marked this point "V. P."

(See Plate)

At a point 76.5 feet northerly, along the same rock rib, marked west face of rock as follows;—

A. C. C. July 15,
1906
 
Pt, of
ice
with
  Sight line is parallel to face
of glacier as nearly as could
be judged.
  in line
rock mark'd
"A" on opp. bank
(Sherzer)
 

On west bank of stream, on old lateral moraine, found large boulder marked by Dr. Sherzer as follows:—

"Sr"

"A 8/17/'04"

"X To ice 79·4 ft."

Measured from this boulder to nearest ice on left hand = 79.6 feet; and to nearest ice on right hand = 89.5 feet.

VIEW OF THE ICE FOREFOOT OF THE YOHO GLACIER FROM ROCK No. 2

SHOWING ICE SNOUT OF YOHO GLACIER, ON JULY 15, 1906, FROM VIEW POINT 6½ FEET NEARER ICE THAN THE VAUX MARKS OF 1902

Sketch showing the Position of Plates set on Yoho Glacier to mark rate of flow.

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  1. Active members of the Alpine Club of Canada.