undifferentiated rock units

Paleontology and geology

Along the northwestern edge of the ancient continent of Laurentia (which is now the western edge of North America), a broad carbonate platform continued to develop. Warm waters of this shallow limy sea were home to a great diversity of animals including graptolites, trilobites, brachiopods, colonial corals, bryozoans, and stromatoporoids (sponge-like animals with calcareous skeletons). Although not shown on this map, Ordovician sandstones, shales, conglomerates, cherts, dolostones, and some altered sedimentary rocks in California are found mainly in the White Mountains, Inyo Mountains, and in places around Death Valley.