| Powell Formation Stratigraphic range: Ordovician | |
|---|---|
| Type | Formation |
| Underlies | Everton Formation |
| Overlies | Cotter Formation [1] |
| Lithology | |
| Primary | Dolomite |
| Other | Shale, sandstone, chert |
| Location | |
| Region | Arkansas, Missouri and Virginia |
| Country | United States |
| Type section | |
| Named for | Powell railroad station (now abandoned), Marion County, Arkansas [2] |
| Named by | Edward Oscar Ulrich |
The Powell Formation or Powell Dolomite is a geologic formation in northern Arkansas, southeast Missouri [3] and Virginia. It contains gastropod, cephalopod, and trilobite fossils dating back to the Ordovician Period. [3]
The Lockport Dolomite is a geologic formation in Ohio. It preserves fossils dating back to the Silurian period.
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 Davis Formation is a geologic formation in Indiana and Missouri. It preserves fossils dating back to the Cambrian period.
The Keokuk Limestone is a geologic formation in Illinois, Iowa and Missouri. It preserves fossils dating back to the Mississippian sub-period.
The Warsaw Formation is a geologic formation in Illinois, Iowa and Missouri. It preserves fossils dating back to the Mississippian subperiod.
The Roubidoux Formation is a geologic formation in the Ozarks of Missouri and in Virginia. It preserves fossils dating back to the Ordovician period.
The Cotter Formation is a geologic formation in Arkansas, Missouri, Oklahoma and in Virginia. It preserves fossils dating back to the Ordovician period.
The Fernvale Limestone is a geologic formation in Alabama, Arkansas, Illinois, Missouri, Oklahoma, and Tennessee. It preserves fossils dating back to the Ordovician period.
The Tomstown Dolomite or Tomstown Formation is a geologic formation in Maryland, Pennsylvania, Virginia and West Virginia. It preserves fossils dating to the Cambrian Period.
The Everton Formation is a geologic formation in northern Arkansas that dates to the middle Ordovician Period. Unconformities separate this formation from the underlying Powell Formation and the overlying St. Peter Sandstone Formation. Named for the town of Everton in Boone County, Arkansas in 1907, the Everton Formation is composed primarily of dolomite, limestone, and sandstone.
The Smithville Formation or Smithville Dolomite is a geologic formation in Arkansas. It preserves fossils dating back to the Ordovician period.
The Theodosia Formation is a geologic formation in Missouri. It preserves fossils dating back to the Ordovician period.
The Burlington Limestone is a geologic formation in Missouri, Iowa and the Midwest region. It preserves fossils dating back to the Mississippian subperiod.
The Compton Limestone is a geologic formation in southwest Missouri. It preserves brachiopod and echinoderm fossils of the Mississippian subperiod. The Compton rests unconformably on the Cotter Dolomite of Ordovician age. The Compton was named for the community of Compton, Missouri as the type sections were described for outcrops along the James River and its tributary the Compton Branch.
The Fern Glen Formation is a geologic formation in eastern and southeastern Missouri. It preserves fossils dating back to the Osagean Series of the Mississippian subperiod.
The Jefferson City Formation or Jefferson City Dolomite is a geologic formation in the Ozarks of Missouri and Arkansas. The Jefferson City is in part not differentiated from the Cotter Formation of northern Arkansas. It preserves fossils dating back to the Ordovician period.
The Bowling Green Dolomite is a geologic formation in Missouri. It preserves fossils dating back to the Silurian period.
The Ely Springs Dolomite is an Ordovician period geologic formation in the Southwestern United States.
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 Huntersville Chert or Huntersville Formation is a Devonian geologic formation in the Appalachian region of the United States. It is primarily composed of mottled white, yellow, and dark grey chert, and is separated from the underlying Oriskany Sandstone by an unconformity. The Huntersville Chert is laterally equivalent to the Needmore Shale, which lies north of the New River. It is also laterally equivalent to a sandy limestone unit which is often equated with the Onondaga Limestone. These formations are placed in the Onesquethaw Stage of Appalachian chronostratigraphy, roughly equivalent to the Emsian and Eifelian stages of the broader Devonian system.
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