The Sharon Sandstone is a thick, nearly pure quartz sandstone of Early Pennsylvanian age that forms spectacular scenic features in several areas of the state and is quarried as a source of silica sand. Lenses of white quartz pebbles are common. The primary outcrops of the Sharon Sandstone are in southern Ohio, especially in Jackson County, and in northeastern Ohio in the Summit, Geauga, and Portage counties area. In both of these regions, the erosion-resistant Sharon Sandstone forms high cliffs and rock-shelter caves. The purity of the Sharon suggests that the quartz grains have gone through several cycles of erosion and deposition, which removed softer rock fragments and rounded the quartz grains. The Sharon in northern Ohio is interpreted to have been deposited by streams flowing southward from the Canadian Shield, whereas the southern Sharon appears to be slightly older and deposited by streams flowing northward into the Ohio basin from Appalachian uplands to the south.