Preliminary study of crevasse formation : Blue Ice Valley, Greenland, 1955
Meier, Mark Frederick, 1925-; Conel, J. E.; Hoerni, J. A.; Melbourne, William G., 1930-; Pings, C. J.; Walker, P. T.
Technical ReportAbstract: A quantitative study of some aspects of the geometry, mechanics, and thermodynamics of crevassing was made during the summer of 1955 on the Greenland Ice Cap east of Thule. Net accumulation in the small study area ranged from about +1.7 m to -0.2 m depending on slight changes in surface slope. Instruments were placed in and between three straight, parallel crevasses which showed a regular increase in width, length, depth, and opening rate. In the vicinity of crevasse walls, the firn was more icified but had fewer and thinner ice layers than elsewhere. Crevasse walls were coated with a thin layer of drip ice with vertically oriented crystal axes. Crevasses were over one-fourth filled with secondary deposits concentrated as icicles and irregular masses near the top. Snow bridges were extremely irregular in thickness, shape, and strength. Small crevasse-wall displacements were measured with a specially adapted electronic strain-gage system. Crevasse opening rates decreased linearly with depth and were very jerky at the surface. Crevasse opening relieved almost all of the strains in intercrevasse blocks. Measured velocity gradients allowed computation of the horizontal projection of the surface strain-rate field, which showed that crevasses were forming only where the surface elongation exceeded about 0.01 per year, and that crevasses were apparently not forming perpendicular to the greatest elongation. Isotherms were mapped in a crevasse air space and 5 m into the wall. NOTE: This file is very large. Allow your browser several minutes to download the file
U.S. Army Snow, Ice, and Permafrost Research Establishment.Engineer Research and Development Center (U.S.)
Glaciers; Glacier ice; Glaciology; Crevasses; Ice crevasses; Ice mechanics; Ice physics; Snow mechanics; Snow physics; Shear stress; Strain rate; Deformation; Meteorological factors; Meteorology; Climate; Climatology; Blue Ice Valley, Greenland
SIPRE report ; 38.
Approved for public release; distribution is unlimited.