In western Kansas, Mississippian rocks are all marine (except for some Chesteran rocks) and all in the subsurface. Unconformities set off dominantly carbonate Mississippian rocks from Pennsylvanian rocks above and Cambrian to Devonian rocks below. Diagenetic alterations, facies changes, and karst complicated the establishment of lateral stratigraphic equivalents. Dolomitization, silicification of fossils, and chertification are widespread. Conodont faunas are correlated with conodont biostratigraphic zones of the type area of Mississippian rocks. The primary sediment source of Osagian and Meramecian rocks was biogenetic. An increased content of clastic (quartz) rocks in upper Meramecian strata marks and important change in sediment source. In Chesteran rocks, sandstone, siltstone, and thin limestone beds predominate.