The Wasatch Plateau of south-central Utah is a large table-like remnant of high ground not yet destroyed by the general erosion of the Colorado River system. The basic structure is monoclinal with a regional westward dip that is gentle on the east and steep on the west. Superimposed on the basic structure is a broad anticline, the Monument Peak uplift, consisting of two folds that plunge slightly east of north into the Uinta basin. These folds, in turn, are modified by a north-trending system of fault zones which fall into the North Gordon, Pleasant Valley, and Joes Valley zones. The Joes Valley zone is largest, having a total length of about 75 miles and an average width of 2 miles. It and the other zones are splintered by numerous small faults and the downward displacem nt reaches a maximum of 3,000 feet.

The regional westward dip of the Plateau is related to the origin of the San Rafael Swell. The greatest folding of the Swell must have been post-Cretaceous pre-Eocene by analogy with the Water-pocket fold on the south. Since the Monument Peak uplift shows structural alignment with the Swell, it probably originated at the same time.

The complex fault zones are obviously of later origin. They are tensional features and cut all surface rocks including Pleistocene moraines. They are related to the deep-seated Wasatch monocline and probably to subsidence and solution effects in the salt-bearing Jurassic rocks below. The western flank of the Wasatch Plateau is complex with numerous faults, unconformities, and landslides. This complexity may be due to growth and collapse of salt structures.

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