Diastrophic importance of the unconformity at the base of the Berea grit in Ohio
Introduction In 1874 J. S. Newberry made the following statements in the Ohio reports: “In most localities where the Bedford shale is exposed the upper surface is very irregular, and it; is evident that the formation has been extensively eroded by the agency which transported the beds of sand, now consolidated into, the Berea grit.” 2 “The best exposures of the entire thickness of the Bedford shale are on the Black River below Elyria. . . . It will also be noticed here that the upper surface of the shale is very irregular, showing that the currents of water which transported the sand—now the Berea sandstone—cut away the shale, then a red clay, in broad and deep channels. As these were filled with sand, the under surface of the sandstone is very uneven and its thickness variable.” 3 This unconformity, noted so long ago by Newberry, is wide-spread, . . .