The Silurian salt deposits in eastern Lake, northwestern Ashtabula, and northeastern Geauga Counties, Ohio

Five salt zones, comprising single or multiple salt beds interbedded with dolomite, dolomititc shale and anhydrite, occur in a 250-square-mile area in eastern Lake, northwestern Ashtabula, and northeastern Geauga Counties, Ohio. The aggregate thickness of salt-bearing rocks, from the base of the lowest salt to the top of the highest salt, ranges from about 300 feet in the northern part of the area to more than 450 feet in the southern part. The aggregate thickness of salt, exclusive of the intervening rocks, also increases southward, from about 100 feet to more than 200 feet. The thickest salt bed, the F1A salt, is 35 to 38 feet thick in the northeastern Geauga and southeatern Lake Counties.