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The type locality is the Mazon River (or Mazon Creek), a tributary of the Illinois River near Morris, Grundy County, Illinois. The 25 to 30 meters of shale were formed approximately , during the Pennsylvanian period. The fossiliferous concretions are usually found within the thickest deposits of the Francis Creek Shale.
A concretion is a hard and compact mass formed by the precipitation of mineral cement within the spaces between particles, and is found in sedimentary rock or soil. [1] Concretions are often ovoid or spherical in shape, although irregular shapes also occur.
Paleogeographic reconstruction showing the Illinois Basin area during the Middle Devonian period. [9] Almost all Silurian rocks in Illinois are deep-water limestone and dolomite deposits; reef habitats were common, and fossils of reef organisms are locally highly abundant, including corals, brachiopods, crinoids, stromatoporoids, and bryozoans. [6]
The Mississippian Borden Formation is a mapped bedrock unit in Kentucky, Indiana, Illinois, Ohio, West Virginia, [7] and Tennessee. It has many members, which has led some geologists to consider it a group (for example in Indiana [ 8 ] ) rather than a formation (for example in Kentucky [ 1 ] [ 4 ] ).
Hiking columnist Susan Anderson stopped by Garden of the Gods Recreational Area in southern Illinois, one of the most photographed areas of the state. A Hiker's Path: Sandstone scenes at the ...
The Jordan sandstone is the light grey rock in the lower third of this outcrop, the Oneota (dolomitic carbonate) is the orange grey rock in the upper two thirds of the road-cut. The Jordan is overlain by the Oneota Formation, a dolomitic carbonate unit of early Ordovician Age. [ 15 ]
A concretion is a volume of sedimentary rock in which a mineral cement fills the porosity (i.e. the spaces between the sediment grains). The image shows a Sandstone Concretion in the wall at the beach of Año Nuevo State Reserve. This concretion was too high in the wall to place a ruler, but I estimate it to be about 400 mm long.
Hanging Rock is a natural sandstone rock formation overhanging the Wabash River in Wabash County, Illinois, in the United States. The rock formation is north of the town of Mount Carmel, Illinois, and located on land originally purchased by Thomas S. Hinde. The formation was formed while the glaciers melted and carved the landscapes of North ...