Casselman Formation

{{Short description|Geological formation in the United States}}

{{Infobox rockunit

| name = Casselman Formation

| image = Casselman Fm I-76.jpg

| caption = Outcrop of Casselman Formation at Mile Marker 84.2, Pennsylvania Turnpike

| type = sedimentary

| age = Pennsylvanian

| period = Pennsylvanian

| prilithology = shale, siltstone, sandstone, red beds, coal

| otherlithology = limestone

| namedfor = Casselman River

| namedby = N. K. Flint, 1965Flint, N.K., 1965, Geology and mineral resources of southern Somerset County, Pennsylvania: Pennsylvania Geological Survey County Report, 4th series, no. 56A, 267 p.

| region = Appalachian Plateau

| country = United States

| coordinates =

| unitof = Conemaugh Group

| subunits =

| underlies = Monongahela Group

| overlies = Glenshaw Formation

| thickness =

| extent = Ohio, Pennsylvania, Maryland, West Virginia

| area =

| map =

| map_caption =

}}

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 between these two units is the top of the marine Ames Limestone.Assessment of Appalachian Basin Oil and Gas Resources: Carboniferous Coal-bed Gas Total Petroleum System http://pubs.usgs.gov/of/2004/1272/2004-1272.pdf The Conemaugh Group overlies the Upper Freeport coal bed of the Allegheny Formation and underlies the Pittsburgh coal seam of the Monongahela Group.