page_title: Geology of the Capitol Reef area
section_title: Erosion
hierarchical_section_title: Geology of the Capitol Reef area / Uplift and Cenozoic events / Erosion
caption_attribution_description: English: This detailed astronaut photograph shows part of Big Thomson Mesa, near the southern end of Capitol Reef National Park. Capitol Reef National Park is located on the Colorado Plateau, which occupies the adjacent quarters of Arizona, Colorado, New Mexico, and Utah. Big Thomson Mesa (image left) is part of a large feature known as the en:Waterpocket Fold. The Fold is a geologic structure called a monocline—layers of generally flat-lying sedimentary rock with a steep, one-sided bend, like a carpet runner draped over a stair step. Geologists think that monoclines on the Colorado Plateau result from faulting (cracking) of deeper and more brittle crystalline rocks under tectonic pressure; while the crystalline rocks were broken into raised or lowered blocks, the overlaying, less brittle sedimentary rocks were flexed without breaking. The portion of the Waterpocket Fold illustrated in this image includes layered rocks formed during the Mesozoic Era (about 250 – 65 million years ago). The oldest layers are at the bottom of the sequence, with each successive layer younger than the preceding one going upwards in the sequence. Not all of the formation’s rock layers are clearly visible, but some of the major layers (units to geologists) can be easily distinguished. The top half of the image includes the oldest rocks in the view: dark brown and dark green Moenkopi and Chinle Formations. Moving toward the foot of the mesa, two strikingly coloured units are visible near image centre: light red to orange Wingate Sandstone and white Navajo Sandstone. Beyond those units, reddish brown to brown Carmel Formation and Entrada Sandstone occupy a topographic bench at the foot of a cliff. The top of the cliff face above this bench—Big Thomson Mesa—is comprised of brown Dakota Sandstone. This sequence represents more than 100 million years of sediments being deposited and turned into rock. Much younger Quaternary (2-million- to approximately 10,000-year-old) deposits are also present in the view. The area shown in this astronaut photograph is located approximately 65 kilometers to the southeast of Fruita, UT near the southern end of Capitol Reef National Park. ISS Crew Earth Observations: ISS020-E-9861 Identification Mission ISS020 (Expedition 20) Roll E Frame 9861 Country or Geographic Name USA-Utah Features WATERPOCKET FOLD, BIG THOMSON MESA Center Point Latitude 37.7° N Center Point Longitude -111.0° E Camera Camera Tilt 34° Camera Focal Length 800&#160;mm Camera Nikon D3 Film 4256 x 2832 pixel CMOS sensor, 36.0mm x 23.9mm, total pixels: 12.87 million, Nikon FX format. Quality Percentage of Cloud Cover 0-10% Nadir What is Nadir? Date 2009-06-14 Time 13:48:49 Nadir Point Latitude 39.3° N Nadir Point Longitude -109.7° E Nadir to Photo Center Direction Southwest Sun Azimuth 76° Spacecraft Altitude 183 nautical miles (339&#160;km) Sun Elevation Angle 20° Orbit Number 554
context_page_description: The exposed geology of the Capitol Reef area presents a record of mostly Mesozoic-aged sedimentation in an area of North America in and around Capitol Reef National Park, on the Colorado Plateau in southeastern Utah.
  Nearly 10,000 feet of sedimentary strata are found in the Capitol Reef area, representing nearly 200 million years of geologic history of the south-central part of the U.S. state of Utah. These rocks range in age from Permian to Cretaceous Rock layers in the area reveal ancient climates as varied as rivers and swamps, Sahara-like deserts, and shallow ocean.
  The area's first known sediments were laid down as a shallow sea invaded the land in the Permian. At first sandstone was deposited but limestone followed as the sea deepened. After the sea retreated in the Triassic, streams deposited silt before the area was uplifted and underwent erosion. Conglomerate followed by logs, sand, mud and wind-transported volcanic ash were later added. Mid to Late Triassic time saw increasing aridity, during which vast amounts of sandstone were laid down along with some deposits from slow-moving streams.
context_section_description: Ten to fifteen million years ago the entire region was uplifted several thousand feet (well over a kilometer) by the creation of the Colorado Plateaus. This time the uplift was more even, leaving the overall orientation of the formations mostly intact. Most of the erosion that carved today's landscape occurred after the uplifting of the Colorado Plateau with much of the major canyon cutting probably occurring between 1 and 6 million years ago. Even in this desert climate, water is the erosional agent most responsible for the carving of the landscape. The pull of gravity, in the form of rock falls or rock creep, plays a major role in the shaping of the cliff lines. Wind is a minor agent of erosion here.
  The drainage system in the area was rearranged and steepened as the Waterpocket Fold was uplifted. Larger streams, such as the Fremont River, were more likely to keep up with the uplift by downcutting into the Waterpocket Fold faster. Other streams, such as Sand Creek, changed their course by flowing parallel to the fold and cutting into less resistant formations. Yet other streams tried to keep up with the uplift by carving slot canyons only to later change course, leaving their canyons literally high and dry. A total of 7,000 feet (2,100 m) of overlying Mesozoic and Cenozoic sediment has been removed by erosion in the area.
  Wetter and cooler conditions developed during the Pleistocene epoch and briefly returned via at least two neoglacial episodes (little ice ages) in the current epoch, the Holocene. The various rivers and streams in the area were engorged by increased precipitation and with melt-water from mountain glaciers on the Henry Mountains to the east and the Aquarius Plateau to the west of the park. Flash floods, mass wasting of hillsides, frost wedging, and landslides all contributed to a significantly faster rate of erosion. Glaciers plucked 20- to 30-million-year-old black basaltic boulders from atop Boulder and Thousand Lake Mountains that were subsequently deposited over the park area by meltwater streams from the glaciers, rockslides and floods.
caption: Big Thomson Mesa seen from space
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