The Ames Limestone is a

geologic formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...

Ohio Ohio () is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. Of the List of states and territories of the United States, fifty U.S. states, it is the List of U.S. states and territories by area, 34th-l ...

Kentucky Kentucky ( , ), officially the Commonwealth of Kentucky, is a state in the Southeastern region of the United States and one of the states of the Upper South. It borders Illinois, Indiana, and Ohio to the north; West Virginia and Virgini ...

Pennsylvania Pennsylvania (; (Pennsylvania Dutch: )), officially the Commonwealth of Pennsylvania, is a state spanning the Mid-Atlantic, Northeastern, Appalachian, and Great Lakes regions of the United States. It borders Delaware to its southeast, Ma ...

and

West Virginia West Virginia is a state in the Appalachian, Mid-Atlantic and Southeastern regions of the United States.The Census Bureau and the Association of American Geographers classify West Virginia as part of the Southern United States while the ...

. It is part of the Conemaugh Group. Formerly know at "Crinoidal Limestone" and "Green Fossiliferous Lime" it was renamed to Ames. Fossils of

Echinoderm An echinoderm () is any member of the phylum Echinodermata (). The adults are recognisable by their (usually five-point) radial symmetry, and include starfish, brittle stars, sea urchins, sand dollars, and sea cucumbers, as well as the s ...

Brachiopod Brachiopods (), phylum Brachiopoda, are a phylum of trochozoan animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear end, ...

, and Gastropoda are commonly found in the Ames.

Description

The Ames is a thin

Marker bed Marker horizons (also referred to as chronohorizons, key beds or marker beds) are stratigraphic units of the same age and of such distinctive composition and appearance, that, despite their presence in separate geographic locations, there is no do ...

Limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms wh ...

and/or

Fossiliferous limestone Fossiliferous limestone is any type of limestone, made mostly of calcium carbonate (CaCO3) in the form of the minerals calcite or aragonite, that contains an abundance of fossils or fossil traces. The fossils in these rocks may be of macroscop ...

. It marks a transition from a predominantly marine environment to predominantly alluvial environment. The Ames serves as a marker for the boundary for the

Casselman Formation The Casselman Formation mapped sedimentary bedrock unit in Pennsylvania, Maryland, and West Virginia, of Pennsylvanian age. It is the uppermost of two formations in the Conemaugh Group, the lower being the Glenshaw Formation. The boundary betw ...

and the

Glenshaw Formation The Glenshaw Formation is a mapped sedimentary bedrock unit in Pennsylvania, Maryland, West Virginia, and Ohio, of Pennsylvanian age. It is the lower of two formations in the Conemaugh Group, the upper being the Casselman Formation. The bounda ...

References

{{reflist Carboniferous Ohio Carboniferous geology of Pennsylvania