Abstract

The Wasatch Plateau, northernmost of the High Plateaus of Utah, was occupied by Pleistocene glaciers. The plateau is a high, rugged mass, deeply dissected. In the glaciated areas the bedrock formations are sandstone, shale, and limestone of late Cretaceous and early Tertiary age. Here, in general, the rocks lie nearly flat, but they are cut by systems of normal faults among which graben are prominent. The drainage system evolved in this bedrock setting gave rise to a geomorphic foundation on which a somewhat unusual group of glacial phenomena developed. The largest group of glaciers issued eastward from deep canyons in the main western body of the plateau into a north-south graben valley, where they coalesced to form large, sheetlike compound moraines. The cirques and other erosional evidences of the glaciation are similar to those usual in the Cordilleran region excepting peculiarities of outline produced by the flat-lying, slightly resistant sedimentary rocks of the plateau, as contrasted with the usual mountain assemblage of strongly disturbed hard rocks. The glaciers were localized, in part independently of altitude, probably in large part because of snow distribution similar to that of today. The glaciation was clearly later than most of the faulting in the plateau, but in the central and southern parts some faulting has occurred since. All moraines so far recognized are unmistakably Wisconsin in age. There is no evidence of older glaciation comparable to that in the nearby Wasatch and Uinta Mountains, where pre-Wisconsin ice was more extensive than the Wisconsin; this raises questions that are only partly answered.

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