Geologic units in Mason county, Kentucky

Ashlock Formation, Grant Lake and Calloway Creek Limestones, and Fairview Formation, undivided (Ordovician) at surface, covers 55 % of this area

Ashlock Formation, Grant Lake and Calloway Creek Limestones, and Fairview Formation, undivided

Bull Fork Formation (Ordovician) at surface, covers 21 % of this area

Bull Fork Formation

Garrard Siltstone and Kope and Clays Ferry Formations, undivided (Ordovician) at surface, covers 21 % of this area

Garrard Siltstone and Kope and Clays Ferry Formations, undivided

Drakes Formation (Ordovician) at surface, covers 1 % of this area

Drakes Formation

Alluvium (Pleistocene to Holocene) at surface, covers 1 % of this area

Alluvium; includes glacial deposits along the Ohio River and its tributaries west of Cannelton locks

Glacial deposits, undifferentiated (Pleistocene to Holocene) at surface, covers 0.5 % of this area

Glacial deposits, undifferentiated; shown locally

Crab Orchard Formation and Brassfield Dolomite, undivided (Silurian) at surface, covers 0.4 % of this area

Crab Orchard Formation and Brassfield Dolomite, undivided; locally includes Bisher Dolomite in Estill County

Point Pleasant Formation (Ordovician) at surface, covers < 0.1 % of this area

Limestone (60%) and shale (40%) interbedded; gray to bluish gray weathers light gray; planar to lenticular, thin to medium bedded; 0 to 80 feet thick.

Kope Formation (Ordovician) at surface, covers < 0.1 % of this area

Shale (75%) and limestone (25%) interbedded; gray to bluish gray weathers light gray to yellowish gray; planar, thin to thick bedded; 200 to 260 feet thick.