As it proceeds east, the formation thickens, rises to the surface, and contains greater amounts of siltstone.

John Strong Newberry, director of the Ohio State Geological Survey, first identified the formation in 1873.

[6] The amount of siltstone increases from west to east, at times forming beds up to 50 feet (15 m) thick.

[5] The Chagrin Shale is found in north-central and northeastern Ohio, and in northwestern Pennsylvania.

[12] The Chagrin Shale is interpreted as having accumulated in a shallow marine, offshore to nearshore environment of normal salinity and less than 45 meters water depth.

On some occasions, these pockets of gas have proven quite large, and when reached by drills have vented for several weeks.