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The Depth of Crevasses

Published online by Cambridge University Press:  30 January 2017

Weston Blake Jr.
Weston Blake Jr.*
Affiliation:
147-A Newton St., Weston 93, Mass., U.S.A.
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Type
Correspondence
Information
Journal of Glaciology , Volume 2 , Issue 19 , 1956 , pp. 644 - 645
Copyright
Copyright © International Glaciological Society 1956

The Editor,

The Journal of Glaciology

Sir,

In reference to the discussion of crevasse depths in the Journal of Glaciology, Vol. 2, No. 17, 1955, p. 511–14, I can add a little information from north-west Greenland.

During the summer of 1954 I had the opportunity to investigate in detail several crevasses on the ice cap in the Thule area. These occurred on both level portions of the ice cap and on the slopes of the various ice domes. The crevasses ranged in width from a 1 ft. crack to large ones 20–25 ft. (6–7.6 m.) wide. The greatest depth recorded was 85 ft. (26 m.); the least, 30 ft. (9 m.). Most of the crevasses were V-shaped, being 4–10 ft. wide near the top, and pinching out 40–50 ft. below the surface. Descents were made in as many crevasses as possible, and the others were measured by hand line….

The largest crevasse entered was 25 ft. wide at the surface and 80 ft. deep. This was found on the ice cap near a large outlet glacier, so that ice movement was more rapid in this area. This crevasse was bridged for most of its length, but it was partially filled by snow in one place where the bridge had collapsed.

Adjacent to this crevasse were several other much larger ones which were reported as being up to 100 ft. (30.5 m.) wide. Unfortunately, no depth measurements were made on any of these very wide crevasses, but some of them may possibly be over 85 ft. deep.

In reply to a communication Mr. Blake wrote further:—

In reply to your request for total depths of the ice in the crevassed areas near the margin of the ice cap I can say that the ice is usually about 1000–1500 ft. (305–457 m.) thick in these localities. Ice-depth measurements were made at several of these crevasses in 1953 by both seismic means and gravimeter surveys, and the results obtained coincided almost exactly. Further depth measurements were made in 1954 (including some in the vicinity of the largest—the 25 ft. wide, 80 ft. deep one I mentioned), but unfortunately I have not seen the results of this work. Neither do I have any temperature data on the crevasses.

It is to be noted that the possible existence of deeper crevasses in this area is not excluded. Ed.