The Mescal Range, approximately 33 miles east of Baker, is in the central Mojave desert region of southeastern California. Here exposed, are rocks ranging in age from Precambrian to Recent. There are, however, no known sedimentary rocks of Tertiary age.

Paleozoic sedimentary rocks nearly 11,000 feet thick, complexly folded and faulted, are separated from granitic augen gneiss of Lower Precambrian age by the Clark Mountain normal fault. The Paleozoic formations include: Cambrian, Prospect Mountain quartzite and Pioche shale; Cambrian through Devonian, Goodsprings dolomite and Sultan limestone; Carboniferous, Monte Cristo limestone and Bird Spring formation; Permian, Kaibab formation. The Moenkopi and Chinle formations, of Triassic age, are nearly 850 feet thick. The Aztec sandstone and Delfonte dacite, of Jurassic age, aggregate approximately 1,100 feet.

During late Cretaceous time all earlier rocks were deformed by east-west compression. The west-dipping Mescal, Mesquite, and White Line faults represent major thrust faults. Other thrust faults are of an imbricate nature and are exposed on both sides of the Piute Valley. Interphased normal fault movement occurred during the same time interval, as evidenced by the Clark Mountain, Aztec, Piute, and Iron Horse faults, and the Monte Cristo fault system. Widespread zones of breccia, ranging in thickness from 500 feet to a feather edge, probably were formed by tectonic activity. Plutonic rocks of acid and intermediate composition were emplaced during the late stage of the Laramide orogeny. Erosional surfaces may exist between: the Goodsprings dolomite and the Sultan limestone, the Monte Cri to limestone and the Bird Spring formation, the Kaibab formation and the Moenkopi formation, and the Moenkopi formation and the Chinle formation.

In Tertiary (?) time a complex system of dikes, ranging in composition from rhyolite to basalt, was emplaced.

Older alluvium of Pleistocene age, blankets the lower flanks of the Mescal Range. Recent alluvium occurs in the larger stream courses and as a veneer over the older alluvium in the Shadow and Piute valleys.

Geomorphically, the Mescal Range represents a highly dissected upland terrane, which rises about 2,000 feet above a mature surface of moderate relief referred to by Hewett (1956) as the Ivanpah Upland. The maximum elevation found in the Mescal Range is 6,493 feet and is attained just north of the Piute valley on a peak cut in the Bird Spring formation.

The area is noted for the Sulphide Queen carbonate body which occurs in the Lower Precambrian basement rocks 3/4 mile east of the settlement of Mountain Pass. This ore body represents the greatest concentration of rare-earth minerals known in the world. In addition, deposits of lead, zinc,

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silver, gold, and copper ore are found in mineralized zones in the Goodsprings dolomite. Building stone has been quarried from the Aztec sandstone and limestone from the Monte Cristo limestone. A nominal water supply, sufficient for domestic use, is available at Valley Wells Station, Windmill, Clark Mountain Station, the Mountain Pass Mine, and Wheaton Springs.

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