Publication Date:
1979-01-01
Description:
Glacial abrasion has been simulated by turning a grindstone made of ice and crushed quartz between two stone plates within a domestic deep-freeze. Within limits, the speed of rotation, the normal loading, and the temperature of operation can be controlled. The tangential force exerted on one of the stone plates can be measured. The ratio of tangential to normal force, the effective coefficient of friction, is found to vary with the “roughness” of the grindstone, to increase gradually as abrasion proceeds, and to increase with decreasing velocity. Even at very low temperatures (to −26°C), abrasion products accumulated in a pad of ice frozen to the tablet “down-stream” from the grindstone, indicating that a water phase at least momentarily exists. The abraded surface of a fine-grained limestone displays grain-from-grain plucking dominating over abrasion of individual crystals. The abraded surface of a granite, by contrast, shows striations of crystals and rupture of cleavage along individual striae.
Print ISSN:
0022-1430
Electronic ISSN:
1727-5652
Topics:
Geography
,
Geosciences
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