Capitol Reef National Park
by Sara Ogg, 2004
The Waterpocket Fold
Capitol Reef National Park is located in Torrey, Utah. The park was established due to the “scenic rock domes and narrow canyons found along the Waterpocket Fold (www.nps.gov/care)”. The Waterpocket Fold is the main attraction at Capitol Reef, see figure 1.
Figure1. Sketch showing the formation of Waterpocket fold in Capitol Reef National Park, from NPS.
The Waterpocket Fold is a monocline fold that is about 100 miles long. Due
to this fold, rocks on the west side are uplifted more than 7,000 feet higher
than those on the east. The Waterpocket Fold is 50-70 m.y, making it Middle
Eocene to Late Cretaceous in age. The Laramide Orogeny formed the Waterpocket
Fold, “activating an ancient fault (www.nps.gov/care).”
“When the fault moved, the overlying rock layers were draped above the
fault and formed a monocline (www.nps.gov/care).”
Erosion is an on going process with the Waterpocket Fold, and out of the 50-70
million years it’s been here, it has only been visible for the past 15-20
million years. According to the NPS, a waterpocket is defined as “basins
that form in many of the sandstone layers as they are eroded by water.”
The park is named for the most scenic part of the Waterpocket Fold, Capitol
Reef. Although with a name with reef in it, you may think it’s made of
mostly carbonates, but it’s not. Capitol is for “the white domes
of Navajo Sandstone that resemble capitol building rotundas, and reef for the
rocky cliffs which are a barrier to travel, like a coral reef (NPS).”
Capitol Reef holds a tremendous amount of rocks, almost 10,000 feet. The strata
are all sedimentary and range from Permian to Cretaceous in age, click here
for the stratigraphic column in MS Word or PDF
format.. Due to the fold, in the west you can find the older rocks and to the
east you find the younger rocks (NPS). With this abundant amount of lithology,
we can tell what the climate used to be like. We know that the Chinle Formation
shows signs of being an old river or swamp, the Navajo Sandstone shows that
it used to be a “Sahara-like desert”, and the Mancos Shale used
to be a shallow marine environment (NPS). Waterpocket fold ends around the Thousand
Lake Mountain which is located in the northwestern part of the park. Next to
this boundary, Cathedral Valley can be found.
Cathedral Valley is a very colorful, if not the most colorful section of Capitol Reef National Park, figure 2
Figure 2. View of Cathedral Valley, Capitol Reef National Park.
It includes a section called the Painted Desert which has a rainbow of colors such as brown, red, purple, gray, and green. This section is mostly part of the Brushy Basin. “This layer was formed during Jurassic times when mud, silt, fine sand, and volcanic ash were deposited in swamps and lakes (NPS).” Cathedral Valley is known for its monoliths, which were made out of the Entrada Sandstone, figure 3..
Figure 3. Monoliths in Cathedral Valley, Capitol Reef National Park
The Entrada Sandstone used to be a “sandy mud on a tidal flat.” It was then later topped off with the Curtis Formation. One of the processes that add to the scenery is the “flowage and dissolution of gypsum (NPS).” The gypsum is found in the Carmel Formation and is the main process that formed Glass Mountain and the Gypsum Sinkhole. Glass Mountain is just an exposed part of the gypsum found in the Carmel Formation, figure 4
Figure 4. Glass Mountain in Capitaol Reef National Park
We know that a sinkhole is formed due to dissolution, and that’s exactly how the Gypsum Sinkhole formed, the gypsum dissolution, figure 5.
Figure 5. Gypsum sinkhole in Capitol reef National Park.
Dikes and sills are found in Upper Cathedral Valley and are 3 to 6 million
years old. Cathedral Valley got its name from the first superintendent of Capitol
Reef. “The upward-sweeping, tapering lines and three dimensional surfaces
reminded the men of Gothic and Egyptian architecture (NPS).”
Erosion was the major process in forming Capitol Reef National Park. Without erosion, we wouldn’t have these fantastic, exposed rocks. Most of the erosion occurred during the uplifting to form the monocline fold. On the other hand, the formation of the canyon has only been happening for the past 1 to 6 million years. How the rocks form cliffs, slopes, or hills is due to the “responses of the various rock layers to the forces of erosion (NPS).” The areas where no vegetation is found, this is due to the “presence of bentonitic clays in the shale which make an inhospitable environment for plants (NPS).” Along the Fremont River valley, there are black boulders that scatter about. These boulders are a “recent geologic arrivals (NPS).” These boulders are volcanic and are 20 to 30 million years old from and old lava flow. This lava flow now tops Boulder and Thousand Lake Mountains. The “High Plateaus supported small mountain glaciers,” until landslides, debris flows, or maybe even stream outwash from glaciation carried them down. There are many more things that can’t be briefly described, but these are just a few of the beautiful things you can see when you visit Capitol Reef National Park.
Billingsley, G.H., Breed, W.J. and Huntoon, P.W.; 1987; Geologic Map of capitol Reef National Park and vicinity, Utah; Utah Geologic Survey; available online at: http://geology.utah.gov/maps/geomap/parkmaps/index.htm
All other information and images were obtained from the Capitol Reef National Park section on the National Park Service website. (www.nps.gov/care)