Several facies of the Riepe Spring Limestone and its equivalents in Utah, Nevada, and California have been recognized. The most distinctive is limestone with massive, rugose corals. This facies is interpreted as representing low-energy, shallow-shelf deposition, on the basis of sedimentary characteristics and abundance of algae. Generally eastward, the coralline facies is replaced by dolomite and sandstone representing nearshore, restricted environments of deposition. Westward, higher energy and/or deeper water deposits accumulated. The coralline facies forms a band 15-50 mi wide that extends from southern Idaho to southeastern California. In northeastern Nevada and western Utah, this facies forms an enormous westward-directed loop, where it accumulated around an approxim tely westward-trending axis of restricted environments. In southern Nevada and southeastern California, the coralline facies clearly is offset tens of miles in a right-lateral sense on the Las Vegas shear zone and on the Furnace Creek-Death Valley fault zones. Southeast of the Garlock fault, either facies trends shift directions abruptly, or there has been tens of miles of movement in a left-lateral sense.

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