Topographic map of a portion of the lower Mojave Valley, San Bernardino County, California, showing Manix Basin: Supplement 1 from "The Pleistocene fauna of the Manix Beds in the Mojave Desert, California" (Thesis)

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NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. The Manix Beds were deposited in a Pleistocene lake basin that occupied 200 to 300 square miles of the Mojave Desert, near the center of San Bernardino County, California. Three stages of lake deposition are recognized. Arenaceous clays and argillaceous sands, light grayish-green in color, are the predominant lithologies. The first and second lake stages are separated by interpluvial sediments; erosion occurred between the second and third stages. The total thickness of lake and interpluvial deposition in the center of the basin probably exceeded 250 feet. Except for minor faulting, which has affected even the youngest layers, the Manix Beds are essentially undeformed. When Lake Manix first formed, the mammalian fauna included a sabre-tooth cat apparently close to Machairodus, Equus sp. cf. E. scotti, Camelops sp. cf. C. kansanus, a giant camel, and possibly a primitive species of Tremarctotherium. Therefore, an Illinoian age is suggested for the first lake stage. Tortoise and fish remains tend to corroborate this dating. This pluvial stage may be younger, but hardly older, than Illinoian as is indicated by fragmentary remains of what appears to be a small or medium-sized Bison. The Avifauna indicates a late Pleistocene, possibly Tahoe, age for the second lake stage. The molluscan fauna from this lake is possibly of Tahoe times. No vertebrate fossils have been recovered from beds of the third lake stage, but, sequentially, deposition probably took place during the Tioga subage of the Wisconsin. Conformable beneath the Manix Beds are 300 to 400 feet of fanglomerates that are considered to be interpluvial sediments of probable Yarmouthian age. The fanglomerates overlie, with an angular unconformity, Tertiary volcanics that have been highly sheared and deformed, probably by Pasadenan orogenic movements. The extreme coarseness, angularity, and lack of decomposition or sorting of the fanglomerates suggest their deposition during the late phases of the Pasadenan Orogeny in the Yarmouthian interglacial age.

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