Sedimentary Rock Formations
A rock formation is the primary unit of stratigraphy, consisting of a succession of strata useful for mapping or description. A rock formation typical consists of a unique lithology (rock type) that has a relatively defined geologic age and is considered mappable (occurs throughout area or region, both on the surface and in the subsurface. Rock formations can be of igneous, sedimentary, or metamorphic origin. Sedimentary rock formations preserve information (including fossils and sedimentary structures) about the sedimentary environments they formed in. Figures 6-87 to 6-89 are examples of marine sedimentary rock formations.