Quaternary geologic map of Skull Valley, Tooele County, Utah (M-150)

By: D. Sack

Skull Valley lies in the Great Salt Lake drainage basin approximately 40 miles west of Salt Lake City. The nature and distribution of its landforms and surficial deposits reveal that it was subjected to a long period of aridity before becoming an arm of late Pleistocene Lake Bonneville. Physical evidence of Lake Bonneville consists of substantial deposits of lacustrine fines, sand, and gravel. Much of the gravel occurs in large relict beaches, barriers, spits, and tombalos. After the Bonneville lacustral cycle, only the lowest elevations of northern Skull Valley were inundated during the highest levels of Great Salt Lake. Most of the valley has been dominated by subaerial processes in the Holocene, and today Great Salt Lake lies beyond the study area to the northeast. In addition to the drastic fall in lake level, the regional post-Bonneville return to conditions of less effective moisture is evidenced in Skull Valley by extensive alluvial-fan and eolian deposits.

The purposes of this investigation are to map at the scale of 1:100,000 and describe the Quaternary deposits, major shorelines, and piedmont fault scarps in Skull Valley. The Quaternary geology of Skull Valley has not previously been mapped in detail despite the valley's large size, accessibility, location near military installations, and proximity to the densely populated Wasatch Front. It is important to study the Quaternary deposits of Skull Valley because they are extensive, of potential economic value, useful in regional Quaternary paleoenvironmental reconstructions, and helpful in identifying local geologic hazards. Surficial geologic mapping is also warranted here because Skull Valley has been and probably will again be considered as the site of large-scale military, industrial, and research-oriented construction projects. Increasing the state's information base regarding the nature and distribution of basin material will aid the decision-making process regarding such large-scale projects.

Other Information:
Published: 1993
Pages: 16 p.
Plates: 1 pl.
Scale: 1:100,000
Location: Tooele County
Media Type: Paper Map