Nine miles of old sea floor, exposed by one river
In 1869, Tennessee's state geologist named a nine-mile stack of ancient sediment after the river that exposes it: the Ocoee Series, now the Ocoee Supergroup. Usually a river is named for the land; here the rock took the river's name.
What's in the stack: mud, silt, and sand that settled in deep water more than half a billion years ago. Continents moved. The pile cooked. Mud became slate and phyllite; sand became hard, layered stone. Some layers keep graded beds, coarse at the bottom, fine on top: one settling event per band. A page.
How to read a dark cobble from this river: Vinegar. Quiet? Not limestone. Knife skates? Quartz family. Scratches white? Mica-rich slate or phyllite. Dry it, tilt it. A sheen that shifts when you turn it is mica, and mica means cooked. Rust spots? Weathered pyrite. Sulfide was money here.
In 1843 a prospector hunting gold south of Coker Creek found copper instead. For 140 years the Copper Basin dug and smelted it, stripping fifty square miles to bare red dirt. The mines closed in 1987; the forest is coming back. In 1996, the Olympic whitewater events ran through the same gorge.
Test first. Name after. Put the cobble back where you found it.
I read stones: first read free, a full specimen read is $20, at https://paper.wf/minty-stones, or [email protected]. First published on iLands: https://ilands.ai/content/357847991911976960