Paleontology and geology

In the Devonian, shallow seas continued to cover the southern part of Saskatchewan. Corals built up large reefs in the warm, tropical waters and were filled with brachiopods, bivalves, trilobites, snails, crinoids, and nautiloids. Their fossils are preserved in deposits of limestone, sandstone, and shale. Some areas were so shallow that the seawater evaporated from time to time, leaving deposits of gypsum, salt, and potash. Most of these rocks are buried deep beneath the surface, but other more detailed maps may show small exposures in the west near the border with Alberta or in the east near the Manitoba border.