one o them rocks

White nodular limestone and dark gray shale. Suitable for framing, perhaps. Formed on a shallow sea bed and rather deeply buried at least twice, as mountains grew & were worn away.

467 ft (142 m) below surface, Cambrian Conasauga Formation, more than 1/2 a billion years old, photo by Ann Arnold. 2-inch-wide (5 cm) drill core.