In this area there was a 12-foot-thick coal vein deep underground. In 1951 it caught fire and burned for 26 years. As it burned away, the rocks above were left unsupported and the surface collapsed, forming the depression you are about to enter. Before the fire, the land was level with the top of the stairs.
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Itineraries across USA
Acadia
Arches National Park
Badlands
Big Bend
Biscayne
Black Canyon Of The Gunnison
Bryce Canyon
Canyonlands
Capitol Reef
Carlsbad Caverns
Channel Islands
Congaree
Crater Lake
Cuyahoga Valley
Death Valley
Dry Tortugas
Everglades
Gateway Arch
Glacier
Grand Canyon
Grand Teton
Great Basin
Great Smoky Mountains
Guadalupe Mountains
Haleakalā
Hawaiʻi Volcanoes
Hot Springs
Indiana Dunes
Isle Royale
Joshua Tree
Kenai Fjords
Kobuk Valley
Lassen Volcanic
Mammoth Cave
Mesa Verde
Mount Rainier
North Cascades
Olympic
Petrified Forest
Pinnacles
Rocky Mountain
Saguaro
Shenandoah
Theodore Roosevelt
Virgin Islands
Voyageurs
White Sands
Wind Cave
Yellowstone
Yosemite
Zion