explain under construction USGS home NPS home USGS/NPS banner
geologic provinces banner

Interior Plains Province

clickable province index map Atlantic Coastal Plain Pacific Mountains Colorado Plateau Ozark/Ouachita Interior Highlands Appalachian Highlands Laurentian Upland Columbia Plateau Interior Plains Basin and Range Rocky Mountains

spacer image The Interior Plains is a vast region that spreads across the stable core (craton) of North America. This area had formed when several small continents collided and welded together well over a billion years ago, during the Precambrian. Precambrian metamorphic and igneous rocks now form the basement of the Interior Plains and make up the stable nucleus of North America. With the exception of the Black Hills of South Dakota, the entire region has low relief, reflecting more than 500 million years of relative tectonic stability.
spacer image Throughout the Paleozoic and Mesozoic Eras the mostly low-lying Interior Plains region remained relatively unaffected by the mountain-building tectonic collisions suffered by the western and eastern margins of the continent.
image on the way
Image on the way.

spacer image
spacer image During much of the Mesozoic Era, the North American continental interior was mostly well above sea level, with two notable exceptions. During part of the Jurassic (208-144 million years ago), rising seas flooded the low-lying areas of the continent. Much of the Interior Plains eventually lay submerged beneath shallow Sundance sea.
spacer image Sediments eroding from the rising Rocky Mountains to the west washed into the sea and deposited as layered wedges of fine debris. As sand, mud, and clays accumulated, the Sundance Sea retreated northward. Preserved within the multi-hued sandstones, mudstones, and clays that made up the shoreline, are the remains of countless dinosaurs that roamed the Sundance coast.
spacer image The fossil assemblages concealed within the sedimentary layers of the Morrison Formation are among the world's richest. In some areas, bones of many dinosaurs are concentrated in a very small area, indicating that they were carried during floods, then deposited together beside a stream.
spacer image Once again, during the Cretaceous Period (144-65 million years ago), record high sea levels flooded the continental interior with shallow seas.
spacer image The Interior Plains continued to receive deposits from the eroding Rocky Mountains to the west and Appalachian and Ozark/Ouachita Mountains to the east and south throughout the most recent Era, the Cenozoic. The flatness of the Interior Plains is a reflection of the platform of mostly flat-lying marine and stream deposits layed down in the Mesozoic and Cenozoic Eras.

Dig deeper
-Subprovince index map
-Interior Low Plateaus
-Central Lowland
-Great Plains province
Links to parks
More Province links
Maps and illustrations
Shaded relief with National Park locations
Shaded relief with major and subprovince boundaries
Shaded relief
Image gallery
Province view, XXXXXXX National Park
Province view, XXXXXXX National Park
Province view, XXXXXXX National Park

| Pacific Mountain System| Columbia Plateau | Basin and Range |
| Colorado Plateau | Rocky Mountain System | Laurentian Upland| Interior Plains |
| Interior Highlands | Appalachian Highlands | Atlantic Plain |
| List of parks by province or plate tectonic setting|

| Geomorphic province home | Geologic time | Plate tectonics | Tapestry of Time and Terrain |
horizontal bar
| USGS Geology in the Parks home | NPS Park Geology Tour home |

This site is a cooperative endeavor of the
US Geological Survey Western Earth Surface Processes Team
and the National Park Service.

Please share your comments and suggestions with us!

This page was last updated on 10/10/00