Buff, coarse, crystalline “Austin Marble” with shell casts and molds.
Gray with line crinoid columnal fragments.
Light gray, earthy.
Gray to buff, with numerous ooliths and fossil fragments.
Dense and massive.
Gray, fine to medium-grained “Berea grit”.
Hematite-cemented quartz; orthoquartzite.
Typical green-gray, fissile, clay-rich.
Brownish gray, kerogen-rich; commercial oil source.
Well-cemented, medium-grained orthoquartzite.
Black, soft; most widely mined.
Cemented glacial gravel.
Small, rounded pebbles and tightly cemented granules.
Introduce your students to rocks formed from deposition of sediment.
White, mature, friable.
Dark, waxy, bitumin-rich.
