Fluvioglacial Drift

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Fluvioglacial Drift

 

the deposits of glacial meltwater streams. Two types of fluvioglacial drift are distinguished: proglacial deposits and ice-contact deposits.

Proglacial deposits are formed ahead of the snout of a glacier by meltwater flowing from under the margin of the glacier. Such deposits constitute outwash plains and fluvioglacial terraces, as well as certain ice-margin and radial eskers. The eskers, which are produced by the merging of deltas that accumulate at the sites where meltwater emerges from under the margin of a glacier, are found in the region where the glacier descends into a lake or sea. The contents of proglacial deposits rapidly change from coarse pebbles and cobbly sand to fine-grained cross-bedded sand with increasing distance from the margin of the glacier.

Ice-contact deposits are formed by meltwater flowing through tunnel valleys, ice-walled trenches, and moulins. Such deposits constitute unique landforms called eskers and kames. Ice-contact deposits are greatly heterogeneous in structure. The heterogeneity arises as a result of variations in the contents of the deposits in the area where the drift accumulates. The deposits may contain pebbles, gravel, and poorly sorted or well-scoured cross-bedded sand of various grain sizes ranging down to fine-grained.

E. V. SHANTSER

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.