located in the Pioche Hills located in eastern Lincoln County, Nevada near the historic mining town of Pioche is a formation known which creates The Lower-Middle Cambrian boundary interval within the southern Great Basin and Mojave Desert region. Here in the long outcrop a belt occurs within a mountain chain which trends southward along the west side of the Bristol, Highland, Chief, and Burnt Springs Ranges to Lime Mountain in the Delamar Mountains. With in the shale of these ranges especially the Middle Cambrian Pioche Shale occurs which in the Pioche Hills located in eastern Lincoln County, Nevada. These areas are rich in fossilized trilobites within the prehistoric Cambrian shelf a transect would associated with depth changes across the shelf a prehistoric ocean.
The most efficient way to locate fossilized trilobites is to examine the shale formations both above and below the surface is to dig into the slabby-weathering siliceous shales, exposing fresh sedimentary strata below the surface. Fortunately, most of the shales within a few inches of the surface are severely fractured; hence, little splitting of them is necessary, since they tend to separate from the outcrops in thin sheet-like plates. Watch for the fossil compressions and impressions along the bedding planes of every shale fragment you remove from the hillside exposures. The deeper you dig, though, the more thickly bedded the opaline shales become, until at last it will become necessary to begin splitting the extremely dense, concrete-like rocks. When doing this, always remember to wear safety goggles, or at least some kind of eye protection such as sunglasses. The denser, thick-bedded opaline strata crack apart only with the greatest of applied brute force, thus increasing the likelihood that sharp fragments might launch off the matrix into your eyes. Stand slabs of shale on end, then give them a sure whack with the blunt end of a geology hammer. If you’re fortunate, the sedimentary layers will break apart along their original planes of deposition, revealing perfect carbonized leaf and seed impressions and compressions to their first light of day in approximately 16 million years.