Date of Award:

5-1955

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Geosciences

Department name when degree awarded

Geology

Committee Chair(s)

Clyde T. Hardy

Committee

Clyde T. Hardy

Committee

J. Stewart Williams

Committee

C. Lewis Gazin

Committee

Tukeo Susuki

Abstract

Fluvial and lacustrine sediments of great thickness accumulated in the intermountain basins of the western United States during Tertiary time. The Salt Lake group in northern Utah and parts of surrounding states is a conspicuous stratigraphic unit of these basins. The "beds of light color" in Morgan Valley in the Wasatch Mountains of northern Utah were named the "Salt Lake group" by Hayden (1869) because of similar occurrences in Salt Lake Valley and because he reasoned that the succession could be divided into formations. Similar rocks crop out in Ogden Valley, north of Morgan Valley, and in Cache Valley, Utah and Idaho. Cache Valley is bounded by the Wasatch and Malad Ranges to the west and the Bear River Range to the east (Fig. 1). It extends from the divide between Ogden and Cache valleys about 18 miles south of Logan, Utah, to Red Rock Pass, about 19 miles northwest of Preston, Idaho. The Bear River enters Cache Valley northeast of Preston, Idaho, and leaves through the Bear River Narrows west of Logan, Utah, at a point between the northern end of the Wasatch Range and the Malad Range. Red Rock Pass, northwest of Preston, Idaho, was the outlet of Lake Bonneville.

The Salt Lake group of Cache Valley, as described in this paper, includes three formations: (1) the basal Collinston conglomerate, (2) the Cache Valley formation, and (3) the upper Mink Creek conglomerate. The Cache Valley formation is partly equivalent to the Collinston conglomerate of the southern part of Cache Valley and is overlain by the Mink Creek conglomerate in the northern part of the valley. It consists largely of tuff and some limestone. The upper part of the Cache Valley formation is of Pliocene age, although similar beds in Morgan Valley are as old as late Eocene.

Recent exploration for petroleum in the western United States has concentrated attention on the continental sediments of Tertiary age. Particularly, the commercial discovery of petroleum in volcanic rocks of probable Tertiary age in Nye County, Nevada, has intensified studies of the Salt Lake group and equivalent stratigraphic units of Nevada, Utah, and Idaho. In Cache Valley, these rocks are well enough exposed to warrant a detailed stratigraphic study and correlation with surrounding areas.

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