Adapted from published geologic quadrangle maps

ROCK UNITS TIME UNITS

GEOLOGIC TIME SCALE Gravel Geologic Time Scale adapted from American Association of Petroleum Geologists, Stratigraphic Correlation Charts for Northern Appalachian and FORMATION, Crossbedded Midwestern Basin and Arches MEMBER, or BED sandstone Regions. PERIOD

3 million years Sandstone or sand

Sandstone and shale Alluvium interbedded

Interbedded shale and sandstone

QUATERNARY Glacial deposits Shale and minor sandstone

3 million years Drift The following geologic units are absent because of either nondepos- tion or erosion: Tertiary, Cretaceous, Jurassic, Triassic, Permian, and part Silty shale of the Pennsylvanian. 320 million years

Flint clay

Carbonaceous shale Formations Lee and Breaathitt

Clay shale PENNSYLVANIAN Olive Hill Clay Bed 330 million years

Dolomitic shale Newman Limestone

Interbedded shale and Nada Member limestone; shale dominant

Interbedded limestone Cowbell Member and shale

Interbedded limestone Nancy Member and shale; limestone dominant

Borden Formation Farmers Member Nodular-bedded MISSISSIPPIAN limestone, minor shale Henley Shale Bed

Cherty limestone Sunbury Shale

Dolomitic limestone ? Berea Sandstone

Silty to sandy dolomite Bedford Shale

Soft-sediment deformation 365 million years DEVONIAN Unconformity Ohio Shale 415 million years

Bisher Dolomite

420 million years Crab Orchard Formation SILURIAN Brassfield Formation

425 million years Drakes Formation

Bull Fork Formation

Grant Lake Limestone

Fairview Formation ORDOVICIAN

Upper Part of Ordovician Kope Formation

Point Pleasant Tongue of Clays Ferry Formation

Figure 3. Stratigraphy of rock units along the AA Highway and U.S. 23. 9