Canyonlands National Park is located in the American state of Utah, near city of Moab and preserves a colorful landscape eroded into countless canyons, mesas and buttes by the Colorado River and its tributaries. The rivers divide the park into four districts: the Island in the Sky, the Needles, the Maze and the rivers themselves. While these areas share a primitive desert atmosphere, each retains its own character. The park covers 527.5 mi² (1,366 km²). Canyons are carved into the Colorado Plateau by the Colorado River and Green River.
Island in the Sky is a broad and level mesa to the north of the park between Colorado and Green river with many overlooks from the White Rim, a sandstone bench below the Island, and the rivers, which are another below the White Rim.
The Needles district is named after the red and white banded rock pinnacles which dominate it, but various other forms of naturally sculptured rock such as canyons, grabens, potholes, and a number of arches similar to the ones of the nearby Arches National Park can be found as well. Unlike Arches National Park, however, where many arches are accessible by short to moderate hikes or even by car, most of the arches in the Needles district lie in back country canyons and require long hikes or four-wheel-drive trips to reach them.
This area was once home of the Ancestral Puebloan Indians, of which many traces can be found. Although the items and tools they used have been largely taken away by looters, some of their stone and mud dwellings are well-preserved. The Ancestral Puebloans also left traces in the form of petroglyphs, most notably on the so-called Newspaper Rock near the Visitor Center at the entrance of this district.
The Maze district west of the Colorado and Green rivers is the least accessible section of the park, and one of the most remote and inaccessible areas of the United States.
A detached unit to the north, Horseshoe Canyon unit, contains panels of rock art made by hunter-gatherers from the Late Archaic Period (2000-1000 B.C.) pre-dating the Ancestral Puebloans. Originally called Barrier Canyon, Horseshoe's artifacts, dwellings, pictographs, and murals are some of the oldest in America. It is believed that the images depicting horses date from after 1540 A.D., after the Spanish re-introduced horses to America.
A subsiding basin and nearby uplifting mountain range (the Uncompahgre) existed in the area in Pennsylvanian time. Seawater trapped in the subsiding basin created thick evaporite deposits by Mid Pennsylvanian. This, along with eroded material from the nearby mountain range, become the Paradox Formation, itself a part of the Hermosa Group. Paradox salt beds started to flow later in the Pennsylvanian and probably continued to move until the end of the Jurassic. Some scientists believe Upheaval Dome was created from Paradox salt bed movement, creating a salt dome, but more modern studies show that the meteorite theory is more likely to be correct.
A warm shallow sea again flooded the region near the end of the Pennsylvanian. Fossil-rich limestones, sandstones, and shales of the gray-colored Honaker Trail Formation resulted. A period of erosion then ensued, creating a break in the geologic record called an unconformity. Early in the Permian an advancing sea laid down the Halgaito Shale. Coastal lowlands later returned to the area, forming the Elephant Canyon Formation.
Large alluvial fans filled the basin where it met the Uncompahgre Mountains, creating the Cutler red beds of iron-rich arkose sandstone. Underwater sand bars and sand dunes on the coast inter-fingered with the red beds and later became the white-colored cliff-forming Cedar Mesa Sandstone. Brightly-colored oxidized muds were then deposited, forming the Organ Rock Shale. Coastal sand dunes and marine sand bars once again became dominate, creating the White Rim Sandstone.
A second unconformity was created after the Permian sea retreated. Flood plains on an expansive lowland covered the eroded surface and mud built up in tidal flats, creating the Moenkopi Formation. Erosion returned, forming a third unconformity. The Chinle Formation was then laid down on top of this eroded surface.
Increasingly dry climates dominated the Triassic. Therefore, sand in the form of sand dunes invaded and became the Wingate Sandstone. For a time climatic conditions became wetter and streams cut channels through the sand dunes, forming the Kayenta Formation. Arid conditions returned to the region with a vengeance; A large desert spread over much of western North America and later became the Navajo Sandstone. A fourth unconformity was created by a period of erosion.
Mud flats returned, forming the Carmel Formation and the Entrada Sandstone was laid down next. A long period of erosion stripped away most of the San Rafael Group in the area along with any formations that may have been laid down in the Cretaceous period.
The Laramide orogeny started to uplift the Rocky Mountains 70 million years ago and with it the Canyonlands region. Erosion intensified and when the Colorado River Canyon reached the salt beds of the Paradox Formation the overlying strata extended toward the river canyon, forming features such as The Grabens. Increased precipitation during the ice ages of the Pleistocene quickened the rate of canyon excavation along with other erosion. Similar types of erosion are ongoing, but occur at a slower rate.