Deep Science — Lead, the Deepest Hole in North America

Fifty minutes northwest of Rapid City, the old gold town of Lead clings to the rim of a hole in the earth so vast it has its own weather. For 125 years the Homestake Mine here was the largest and deepest gold mine in North America, its shafts plunging nearly a mile and a half beneath the Black Hills. When the gold ran out, the mine found an extraordinary second life: it is now the Sanford Underground Research Facility, where physicists hunt for dark matter and the nature of neutrinos in laboratories built 4,850 feet underground, shielded from cosmic rays by a mile of solid rock. This day traces Lead's twin identities — the brutal industrial heritage of hard-rock mining and the frontier of modern physics — from the visitor center overlook above the yawning Open Cut to the machinery and miners' stories of the Black Hills Mining Museum.