The Karrens of Columbia, California

Once a band of gold prospectors discovered a peculiar area of spiky limestone protuberances high above the Stanislaus River. Between those spikes lay fist-sized gold nuggets, and soon an army of diggers had plucked the world's richest placer deposit clean. Today Columbia, California, lives for its Gold Rush history, but that odd landscape—a genuine karrenfeld—remains to instruct the student of geomorphology. (That would be you and me.) See what I saw during my recent visit.

Marble karst — Geology Guide photo