Chagrin River - Natural History

Natural History

Along its banks and tributaries Berea sandstone, Bedford shale, Cleveland shale, and Chagrin shale bedrock, are exposed in layers. The river itself was cut through the Allegheny Plateau as glaciers receded in the area at the end of the Wisconsin glaciation.

The lowest visible bedrock is Chagrin shale. Named for the river itself and easily found in the river valley. Chagrin shale, is blue gray in color, an offshore alluvial, silt shale of the Devonian period. This layer is found below about 800 feet (240 m) msl.

The next layer is Cleveland shale. This is a black shale that is an important source of local fossils. Cleveland Shale is found in the Chagrin River valley between 800 and 900 feet (270 m) msl.

Bedford Shale is found above the Cleveland Shale layer. This material marks the uncertain transition between the Devonian and Pennsylvanian periods in the region and is also an important source of local fossils. This layer is found in the ravines that carry tributaries of the Chagrin River . Bedford shale is a sand shale and is characterized by its roughly 90° cleavage pattern. Pieces of Bedford shale can look as if they were cut by human hands and are found up to about 950 feet (290 m) msl.

Berea sandstone is found from around 950 feet (290 m) msl to roughly 1,070 feet (330 m) msl. Berea sandstone, is an important local building material. In the nineteenth century it was quarried from the base of Gildersleeve Mountain (in the East Branch watershed). This material was used to build Kirtland Temple and other local structures. Berea sandstone is still used as a local building material

According to the Ohio Department of National Resources, more than 49 species of fish and 90 bird species live in the Chagrin River watershed, including the American brook lamprey, which is relatively rare in Ohio.