Berea Sandstone

Berea Sandstone, also known as Berea Grit, is a sandstone formation in the U.S. states of Michigan, Ohio, Pennsylvania, West Virginia, and Kentucky. It is named after Berea, Ohio. The sandstone has been used as a building stone and is a source of oil and gas.

In the Appalachian Basin, Berea Sandstone is present in eastern Ohio, western Pennsylvania, western West Virginia, and eastern Kentucky. In the Michigan Basin, the sandstone is present in the eastern part of the state, thickest near Michigan's Thumb. The two deposits are separated by the Cincinnati Arch and are disconnected from each other. The sandstone overlies the Bedford Shale and the Ohio Shale and underlies the Sunbury Shale. Berea Sandstone is light gray to buff-colored in the form of siltstone and fine- to medium-grained sandstone. In places it is hard to distinguish from the underlying Bedford Shale. Berea Sandstone is classified as a member of the Waverly Group. Berea Sandstone is up to 72 meters (236 ft) thick in Lorain County, Ohio, and up to 79 meters (259 ft) thick in Huron County, Michigan.

The sandstone was named "Berea Grit" by Ohio geologist J. S. Newberry in 1874. He named it after Berea, Ohio, for its extensive quarries of the stone.

In Michigan, the petroleum industry has referred to the Ellsworth Shale as "Berea", but this formation is distinct from Berea Sandstone and is laterally separated by Antrim Shale.

Berea Sandstone was formed in the Late Devonian period. Prior to the 1970s, it was assigned a Mississippian age. The Devonian-Carboniferous boundary was realigned based on research from Europe, but various geologists were not aware of the changes and so incorrectly assigned Berea Sandstone to the Kinderhookian (early Mississippian).

The majority of the sand which formed the Berea Sandstone came from the north, flowing in a river from the highlands of eastern Canada. It was deposited in a river delta environment. Pepper, et al., hypothesized that the river flowed first into the Ohio basin before switching course to the Michigan basin, thus the Michigan Berea Sandstone would be slightly younger. There is a downwarp in the Cincinnati arch, called the Ontario sag, that if it was present at the formation of Berea Sandstone, could mean that it formed a continuous belt of sediment between the Appalachian and Michigan basins. Nevertheless, subsequent erosion disconnected the two deposits.

Berea Sandstone is generally unfossiliferous. However some fossils have been found, including fish of the genera Ctenacanthus and Gonatodus, plants of the genus Annularia, and some brachiopods.

Buildings constructed of Berea Sandstone include the Johnson County Courthouse in Iowa and the Brown County Courthouse in South Dakota. The Centre Block building of the Parliament of Canada, both before and after reconstruction, uses Berea Sandstone as window and door trim.