New Releases by Mark Rich

During Late Mississippian, Pennsylvanian, and Permian time, several thousand feet of predominantly carbonate sediments accumulated in southern Nevada and southeastern California. Because of their lithologic unity these rocks constitute a single formation, the Bird Spring Formation. One of the best sections is exposed along the eastern front of the Spring Mountains about 35 miles northwest of Las Vegas, near Lee Canyon, Clark County, Nevada ... There the formation is greater than 7,000 feet thick, is broken only by minor faults, and contains a prolific fusulinid fauna. This report deals with that thick stratigraphic section and its contained fusulinids. An attempt has been made to correlate the various divisions with units in the mid-continent region where the most extensive studies on fusulinids have been made.

The Pancake Summit quadrangle is about 42 miles west of Ely in east-central Nevada. Paleozoic rock formations exposed in the southern portion of the quadrangle range in age from Cambrian to Permian. They consist predominantly of limestone and dolomite, with some shale, sandstone, and conglomerate. On Mount Hamilton, an igneous body is emplaced into the Paleozoic rocks, surrounded by a narrow contact metamorphic zone. Overlaying late Paleozoic rocks in angular unconformity are lake beds of Eocene age. hey are covered in some localities by volcanic tuffs and flows of Tertiary and possibly Quaternary age. Main structural features in the are north-south trending folds which are cut by numerous faults. Basin Range structure is especially conspicuous along the west front of the White Pine Mountains. Stratigraphic displacement of at least 7,000 feet is indicated for a major frontal fault along the ridge. The major portion of block faulting occurred during the interval between Eocene and middle Pleistocene time.