The Munising Group or Formation is a 1,700 feet (520 m) thick, white to light grey Cambrian sedimentary unit that crops out in Michigan and Ontario. At one end of its extent, it comprises a basal conglomerate overlain by the Chapel Rock Member and the Miners Castle Member; elsewhere, it comprises the Eau Claire, Galesville (=Dresbach), and Franconia Members. Anhydritic evaporite deposits are present in places. The conglomerate was deposited by rivers in flood, with the Chapel Rock member, which contains deltaic deposits, representing transgression as the conglomerate cones became submerged; the Miners Castle member was deposited further from the shoreline, representing shelf deposits. Its uppermost strata may be Early Ordovician in age, and contain conodonts, trilobites and phosphatic moulds of brachiopods, ostrocoderm fish and gastropods.
The Jordan Formation is a siliciclastic sedimentary rock unit identified in Illinois, Michigan, Wisconsin, Minnesota, and Iowa. Named for distinctive outcrops in the Minnesota River Valley near the town of Jordan, it extends throughout the Iowa Shelf and eastward over the Wisconsin Arch and Lincoln anticline into the Michigan Basin.
The Traverse Group is a geologic group in Michigan, Indiana and Ohio comprising middle Devonian limestones with calcareous shale components. Its marine fossils notably include Michigan's state stone, the Petoskey stone, among other corals and records of ancient marine life. A range of trilobites has also been found in the Traverse Group.
The Waynesville Formation is a geologic formation in Ohio and Indiana. It preserves fossils from the Late Ordovician period.
The Golconda Formation is a geologic formation in Kentucky. It preserves fossils dating back to the Carboniferous period. In Indiana, the Golconda, it is called the Golconda Limestone and is part of the Stephensport Group.
The Harrodsburg Limestone is a geologic formation, a member of the Sanders Group of Indiana Limestone, of Mississippian age. It was named for Harrodsburg in southern Monroe County, Indiana by T. C. Hopkins and C. E. Siebenthal. It is made up primarily of calcarenite and calcirudite. It also may include some beds of dolomite and shale.
The Osgood Formation, also known as the Osgood Shale is a geologic formation in Indiana, Kentucky, and Ohio. It preserves fossils dating back to the Silurian period.
The Maquoketa Formation is a geologic formation in Illinois, Indiana. Iowa, Kansas, Minnesota, Missouri, and Wisconsin. It preserves mollusk, coral, brachiopod and graptolite fossils dating back to the Darriwilian to Hirnantian stages of the Ordovician period.
The Peedee Formation is a geologic formation in North and South Carolina. A marine deposit, named for exposures along the Great Peedee River, it preserves belemnites and foraminifera fossils dating to the Late Cretaceous (Maastrichtian). The formation is notable for its occurrence of Belemnitella americana, known as the Pee Dee Belemnite (PDB), a long-standing standard in stable carbon isotope research. A single pterosaur femur, possibly an Azhdarchid, from the Peedee formation is one of the few pterosaur body fossils found in Eastern North America.
The Potomac Group is a geologic group in Delaware, Maryland, New Jersey, and Virginia. It preserves fossils dating back to the Cretaceous period. An indeterminate tyrannosauroid and Priconodon crassus, a nodosaurid, are known from indeterminate sediments belonging to the Potomac Group. The Potomac Group was initially believed to have been Late Jurassic in age by Othniel Charles Marsh but later studies, such as Clark (1897), have found that the Potomac Group is in fact Early-Late Cretaceous (Aptian-Turonian) in age.
The Rockdale Run Formation is a geologic formation in Maryland, Pennsylvania, Virginia and West Virginia. It preserves fossils dating back to the Ordovician period.
The Prairie Bluff Chalk is a geologic formation in Alabama and Mississippi. It preserves fossils dating back to the Cretaceous period.
The Potosi Formation is a geologic formation in Missouri, Illinois and Indiana. It preserves fossils dating back to the Cambrian period.
The Windrow Formation is a geologic formation in Minnesota named after Windrow Bluff on Fort McCoy, Monroe County, Wisconsin. It preserves fossils dating back to the Cretaceous period.
The Edwards Group is a geologic group in Texas. It preserves fossils dating back to the Cretaceous period.
The Deseret Limestone, also known as the Pine Canyon Formation, is a geologic formation in Utah. It was formed by the Panthalassa ocean around 340 Ma. It preserves marine fossils dating back to the Carboniferous period or Mississippian age, mostly consisting of tabulate and rugose corals, and other marine invertebrates; vertebrates are represented by conodonts. The Deseret is a 500-foot thick layer of dolomitic limestone with chert, with a basal layer of black shale that is host rock for many Utah caves such as Timpanogos Cave National Monument.
The Elephant Canyon Formation is the basal Permian geologic formation of the Cutler Group overlying an unconformity on the Pennsylvanian Honaker Trail Formation in the Paradox Basin of southern Utah.
The Alexo Formation a stratigraphic unit of Late Devonian age. It is present on the western edge of the Western Canada Sedimentary Basin in the central Rocky Mountains and foothills of Alberta. The formation consists primarily of dolomite. It is locally fossiliferous and includes remains of marine animals such as brachiopods and conodonts.
The Spray River Group is a stratigraphic unit of Triassic age. It is present on the western edge of the Western Canada Sedimentary Basin in the foothills and Rocky Mountains of western Alberta. It was originally described as the Spray River Formation by E.M. Kindle in 1924 and was later raised to group status. Its type section is located in the Spray River gorge at the southern end of Sulphur Mountain.
The Knox Supergroup, also known as the Knox Group and the Knox Formation, is a widespread geologic group in the Southeastern United States. The age is from the Late Cambrian to the Early Ordovician. Predominantly, it is composed of carbonates, chiefly dolomite, with some limestone. There are also cherty inclusions as well as thin beds of sandstone.
