This is a collapsed passage from long ago. As the Green River cut a deeper valley, the water moving down the side of the ridge created an instability in the rocks causing the passage to be closed off. When the room is silent you can still hear the sound of water dripping down the rocks. This breakdown happened long before modern day exploration. With the increase of rainfall, the water can be seen cascading down the rocks and disappearing into the depths of the unknown.
Is there something we missed for this itinerary?
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