is an
impact structure, the deeply eroded bottom-most remnants of an
impact crater 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, became 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 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 ==