The
Waterpocket Fold defines Capitol Reef National Park. A nearly
100-mile-long warp in the earth's crust, the fold is a classic
monocline: a regional fold with one very steep side in an area
of otherwise nearly horizontal rock layers. The Waterpocket Fold
formed between 50 million and 70 million years ago when a major
geologic shift in western North America reactivated an ancient
buried fault. When the fault moved, the overlying rock layers
were pushed up, bent, and draped into the monocline. The fold is
also known as Capitol Reef: "capitol" for the white
domes of Navajo Sandstone that resemble rotundas, and
"reef" for the rocky cliffs that are a barrier to
travel, like a coral reef.
Almost
10,000 feet of sedimentary strata are found in the Capitol Reef
area. These rocks range in age from Permian to Cretaceous, and
this geologic layer cake records nearly 200 million years of
history. Ancient environments revealed in the rock include
rivers and swamps (Chinle and Moenkopi formations), Sahara-like
deserts (Navajo and Wingate Sandstone), and shallow ocean
(Mancos Shale). Cathedral Valley's freestanding monoliths are
carved out of Entrada Sandstone, which was originally deposited
as sandy mud on a tidal flat. Some of the cathedrals are capped
by thin, hard beds of the Curtis Formation, a greenish-gray
marine sandstone.
Most of the
erosion that carved today's landscape occurred after the uplift
of the Colorado Plateau some time within the last 20 million
years. Water was the primary erosional agent; wind was a
secondary influence. Today, both elements, plus the pull of
gravity - in the form of rock falls or rock creep - continue to
shape Capitol Reef's majestic domes, arches, and canyons.
The
Waterpocket Fold defines Capitol Reef National Park. A nearly
100-mile-long warp in the earth's crust, the fold is a classic
monocline: a regional fold with one very steep side in an area
of otherwise nearly horizontal rock layers. The Waterpocket Fold
formed between 50 million and 70 million years ago when a major
geologic shift in western North America reactivated an ancient
buried fault. When the fault moved, the overlying rock layers
were pushed up, bent, and draped into the monocline. The fold is
also known as Capitol Reef: "capitol" for the white
domes of Navajo Sandstone that resemble rotundas, and
"reef" for the rocky cliffs that are a barrier to
travel, like a coral reef.
Almost
10,000 feet of sedimentary strata are found in the Capitol Reef
area. These rocks range in age from Permian to Cretaceous, and
this geologic layer cake records nearly 200 million years of
history. Ancient environments revealed in the rock include
rivers and swamps (Chinle and Moenkopi formations), Sahara-like
deserts (Navajo and Wingate Sandstone), and shallow ocean
(Mancos Shale). Cathedral Valley's freestanding monoliths are
carved out of Entrada Sandstone, which was originally deposited
as sandy mud on a tidal flat. Some of the cathedrals are capped
by thin, hard beds of the Curtis Formation, a greenish-gray
marine sandstone.
