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The Interior Plains are highlighted in red.

The Interior Plains is a vast physiographic region that spreads across the Laurentian craton of North America. This area was originally formed when cratons collided and welded together 1.9-1.8 billion years ago in the Trans-Hudsonian orogeny during the Paleoproterozoic. Image File history File links This is a lossless scalable vector image. ... Image File history File links NorthAmericaInteriorPlains. ... Image File history File links NorthAmericaInteriorPlains. ... This article or section does not adequately cite its references or sources. ... World geologic provinces. ... The Trans-Hudsonian orogeny was a major orogenic event in North America during the Proterozoic. ... The Paleoproterozoic is the first of the three sub-divisions of the Proterozoic occurring between 2500 to 1600 million years ago. ...

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. Quartzite, a form of metamorphic rock, from the Museum of Geology at University of Tartu collection. ... Volcanic rock on North America Plutonic rock on North America Igneous rocks (etymology from latin ignis, fire) are rocks formed by solidification of cooled magma (molten rock), with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks. ... The Black Hills The Black Hills are a small, isolated mountain range rising from the Great Plains of North America in western South Dakota and extending into Wyoming, USA. Set off from the main body of the Rocky Mountains, the region is something of a geological anomaly—accurately described as... Official language(s) English Capital Pierre Largest city Sioux Falls Area  Ranked 17th  - Total 77,163 sq mi (199,905 km²)  - Width 210 miles (340 km)  - Length 380 miles (610 km)  - % water 1. ... The tectonic plates of the world were mapped in the second half of the 20th century. ...

The Great Plains region of the United States and Canada falls within this area. The interior Plains were often covered by shallow inland sea. Sediments from the shield and the Rocky Mountains were deposited in these seas over millions of years. Eventually the sediments were compressed by the weight of the layers above into sedimentary rock. Part of the sedimentary rock deposited in these areas consists of coral reefs that formed close to the surface of seas during the Paleozoic era. The Great Plains covers much of the central United States, portions of Canada and Mexico. ...

Paleozoic and Mesozoic

Throughout the Paleozoic and Mesozoic eras, the mostly low-lying Interior Plains region remained relatively unaffected by the mountain-building tectonic collisions occurring on the western and eastern margins of the continent. During much of the Mesozoic Era, the North American continental interior were mostly well above sea level, with two major exceptions. During part of the Jurassic, rising seas flooded the low-lying areas of the continent, forming the Sundance Sea; in the Cretaceous, much of the Interior Plains region lay submerged beneath the Western Interior Seaway. The Paleozoic Era (from the Greek palaio, old and zoion, animals, meaning ancient life) is the earliest of three geologic eras of the Phanerozoic eon. ... The Mesozoic Era is one of three geologic eras of the Phanerozoic eon. ... // Orogeny (Greek for mountain generating) is the process of mountain building, and may be studied as a tectonic structural event, as a geographical event and a chronological event, in that orogenic events cause distinctive structural phenomena and related tectonic activity, affect certain regions of rocks and crust and happen within... The Jurassic Period is a major unit of the geologic timescale that extends from about 199. ... The Sundance Sea was a shallow inland sea which existed in North America during the Jurassic Period of the Mesozoic Era. ... // The Cretaceous Period is one of the major divisions of the geologic timescale, reaching from the end of the Jurassic Period (i. ... Western Interior Seaway during the mid-Cretaceous, about 100 million years before the present The Western Interior Seaway, also called the Cretaceous Seaway, the Niobraran Sea, and the North American Inland Sea, was a huge inland sea that split the continent of North America into two halves during most of...

Cenozoic

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 era. The flatness of the Interior Plains is a reflection of the platform of mostly flat-lying marine and stream deposits laid down in the Mesozoic and Cenozoic eras. For individual mountains named Rocky Mountain, see Rocky Mountain (disambiguation). ... Appalachians in North Carolina The Appalachian Mountains (French: les Appalaches) are a vast system of mountains in eastern North America. ... This article is about the Ozark Plateau. ... Ouachita Mountains The Ouachita Mountains are a mountain range located in west central Arkansas and east central Oklahoma. ...

General appearance of land

There are rolling hills, and deep, wide valleys. There are slopes downward from west to east and some part is separated by a sharp rise. Cattle is raised in places where the climate is too hot for crops.

External links

• USGS description of the U.S. Interior Plains region