undifferentiated rock units

Paleontology and geology

Cambrian Nevada was a tectonically quiet continental margin, with little or no mountain-building activity. Seas rose gradually, covering the state with water that was only tens of meters deep in some places. To the east, rivers flowed over a flat plain, carrying well-sorted quartz sand to beaches and nearshore areas. Out in the shallow sea, limy sediments accumulated; in deeper water, the muddy bottoms would later become shale. Cambrian fossils of Nevada include trilobites, brachiopods, archaeocyaths, and helicoplacoids. Although not shown on this map (due to scale), Cambrian deposits occur throughout the state.