Date of Award:
Master of Science (MS)
Clyde T. Hardy
The mapped area, in north-central Utah, is located west of Clarkston, Utah. It includes the southern part of Clarkston Mountain and part of the Junction Hills, which extend southward from Clarkston Mountain. The area is represented on the southeastern part of the Portage quadrangle, Utah-Idaho, and the southwestern part of the Clarkston quadrangle, Utah-Idaho. It measures about 8.3 miles in the east-west direction and 4.0 miles in the north-south direction.
The southern part of Clarkston Mountain consists of stratigraphic units that range in age from Cambrian to Silurian. The Nounan Formation of Cambrian age is the oldest. The St. Charles Formation, of Cambrian age, and the Garden City and Swan Peak Formations, of Ordovician age, overlie the Nounan. The youngest unit consists of undifferentiated Fish Haven and Laketown Formations. The Fish Haven is Ordovician and the Laketown is Ordovician and Silurian. In the Junction Hills, the Oquirrh Formation of Pennsylvanian age crops out south of an east-west fault. It is overlapped unconformably by the Salt Lake Formation of Tertiary age. The Lake Bonneville Group of Quaternary age is present in Malad Valley, on the west, and in Cache Valley, on the east.
The rocks of the southern part of Clarkston Mountain dip east. A lowangle thrust fault is present on the eastern side of the mountain. It dips west and movement was eastward. North-trending normal faults, on the eastern side of Clarkston Mountain, are particularly significant. They formed as thrust faults with eastward movement. Later deformation caused reversed movement. North-trending normal faults are also present on the western side of Clarkston Mountain. The area of Junction Hills is separated from Clarkston Mountain by an east-west normal fault. The Oquirrh Formation is faulted down, on the south, opposite Cambrian formations. Marginal normal faults extend along the western and eastern sides of Clarkston Mountain and the Junction Hills. Movement on these faults produced the great relief of Clarkston Mountain.
The folding and thrust faulting occurred during the Laramide deformation . . This deformation is considered to have started by early Cretaceous time and to ha ve continued into early Tertiary. Normal faulting, including reversed movement on original thrust faults, represents Basin and Range faulting. This faulting began early in the Tertiary period and continues at the present time.
Gray, Wayland E., "Structural Geology of the Southern Part of Clarkston Mountain, Malad Range, Utah" (1975). All Graduate Theses and Dissertations. Paper 2114.
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