INVESTIGATION OF SHEAR ZONES IN THE ICE CAP MARGIN, THULE, GREENLAND.
The shear moraine phenomenon of glaciers is examined in the light of new evidence collected in the general Tuto area during 1958-1959. The formation and composition of silt bands, some heavy accumulations of boulders and gravel, and streaks of clayey ice exposed during the excavation of two ice tunn...
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| Format: | Text |
| Language: | English |
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1964
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| Online Access: | http://www.dtic.mil/docs/citations/AD0600074 http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=AD0600074 |
| Summary: | The shear moraine phenomenon of glaciers is examined in the light of new evidence collected in the general Tuto area during 1958-1959. The formation and composition of silt bands, some heavy accumulations of boulders and gravel, and streaks of clayey ice exposed during the excavation of two ice tunnels in the margin of the ice cap are described in detail. Surface investigations have furnished information on the location and concentration of the glacial ice-snow-drift ice interface, variations of silt, sand, and rock bands, and other materials produced by the shear surfaces. A general view of the outcropping shear moraines shows a tendency toward a broad arch-shaped pattern, perpendicular to the direction of flow and, in most cases, parallel to the ice edge. The distance from the ice edge varies from a few dozen feet at the ice cliffs to a half mile and more. Motion measurement between two ice levels is presented in the form of limiting angles on a velocity distribution curve. The indication of great variability in conditions at the edge of the moving ice is discussed in terms of contact zone between the glacier bottom and ground surface, nature of interaction occurring in zones containing glacierground surface interface, and mechanics of the migration of inclusion bands which occur during the formation of glacial shear moraines. (Author) |
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