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 dominant, 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. Gallery See also List of national parks of the United States Bears Ears National Monument Goblin Valley State Park Indian Creek Wilderness Study Area References Further reading External links by the National Park Service Canyonlands Field Institute (a non-profit support group) Canyonlands Natural History Association (a non-profit organization established to assist the scientific and educational efforts of the NPS) Spherical panoramas of Canyonlands DigitalCommons@USU (Canyonlands Research Publications from Utah State University) National parks in Utah Canyons and gorges of Utah Rock formations of Utah Protected areas on the Colorado River Protected areas of Garfield County, Utah Protected areas of Grand County, Utah Protected areas of San Juan County, Utah Protected areas