Colorado has many caves, most of them carved by underground water in
Paleozoic limestone. The Cave of the Winds at Manitou is the only one in
the state which has been developed as a tourist attraction. It is in
highly faulted Ordovician and Mississippian limestone near the mountain
front, where the faulting, coupled with the high relief, has accelerated
solution of the rock by allowing groundwater to percolate downward
rapidly. The cavern was probably carved during the Pleistocene Ice Age,
when surface water and groundwater were much more abundant than at
present. Deposition of stalactites and stalagmites has occurred within
the last few thousand years, as supplies and movement of water have
decreased.
Spanish Cave, above timberline on Marble Mountain in the Sangre de
Cristo Range, is probably the nation’s highest limestone cave. It is in
thick folded and faulted Pennsylvanian reef limestone, at an elevation
of over 12,000 feet. The cave has many intricate passageways branching
from its main vertical tubes and channels.
Fulford Cave, south of Eagle, is in the Mississippian Leadville
Limestone of the northern part of the Sawatch Range. Many other caves
are situated south of Fulford, near Woods Lake, where the limestone is
widely exposed and highly dissected.
Fairy Cave, northeast of Glenwood Springs, is the best known of the many
caverns in the Paleozoic limestones that form the southern flanks of the
White River Plateau.
[Illustration: In Cave of the Winds near Manitou, Paleozoic limestones,
cracked and tilted by uplift of the Front Range, have been honeycombed
by ground water. Calcite stalactites hang from the ceiling, while
stalagmites grow up from the floor. (Cave of the Winds Company photo)]
In the Plateau Province another type of cave is formed not so much by
groundwater as by weathering of the flat-lying alternating beds of
massive resistant sandstone and less resistant, thinly bedded mudstone
and shale. Where the resistant layers are undermined, great arching
caves develop. These are best observed at Mesa Verde National Park,
where many of them once sheltered Indian communities. They can also be
seen in Colorado National Monument and along the Colorado River and
several of its major tributaries.
[Illustration: Along the edge at Mesa Verde, caves in Cretaceous Mesa
Verde sandstone were used for shelter by Indians. Springs near the bases
of the caves, which provided the Indian communities with water, probably
contributed to the undermining of the sandstone cliffs. (Colorado
Department of Highways photo)]