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86-851: The Great Plains are a broad expanse of flatland in North America . The region is located just to the east of the Rocky Mountains , much of it covered in prairie , steppe , and grassland . They are the western part of the Interior Plains , which include the mixed grass prairie , the tallgrass prairie between the Great Lakes and Appalachian Plateau , and the Taiga Plains and Boreal Plains ecozones in Northern Canada . "Great Plains", or Western Plains ,

172-428: A gap ). Coastal plains mostly rise from sea level until they run into elevated features such as mountains or plateaus. Plains can be formed from flowing lava ; from deposition of sediment by water, ice, or wind; or formed by erosion by the agents from hills or mountains. Biomes on plains include grassland ( temperate or subtropical ), steppe ( semi-arid ), savannah ( tropical ) or tundra ( polar ). In

258-464: A "division" there. The Interior Plains of Canada are one of seven physiographic areas included in the highest level classification in that country. That country calls this primary classification level "region." For some of the seven regions, a subregion schema is provided. For other physiographic regions (such as the Interior Plains and Appalachian Uplands) subregions are not developed, but

344-445: A broad denuded area as a piedmont deposit by the rivers which issued from the mountains. Since then, it has been more or less dissected by the erosion of valleys. The central section of the plains thus presents a marked contrast to the northern section. While the northern section owes its smoothness to the removal of local gravels and sands from a formerly uneven surface by the action of degrading rivers and their inflowing tributaries,

430-538: A broad stretch of country underlain by nearly horizontal strata extending westward from the 97th meridian west to the base of the Rocky Mountains , a distance of 300 to 500 mi (480 to 800 km). It extends northward from the Mexican boundary far into Canada. Although the altitude of the plains increases gradually from 600 ft (180 m) or 1,200 ft (370 m) on the east to 4,000–5,000 ft (1,200–1,500 m) or 6,000 ft (1,800 m) near

516-700: A few horses were found by the Spanish among the Indians living at the mouth of the Colorado River of Texas and the Caddo of eastern Texas had a sizeable number. Plain A plain or flatland is a flat expanse of land with a layer of grass that generally does not change much in elevation , and is primarily treeless. Plains occur as lowlands along valleys or at the base of mountains , as coastal plains , and as plateaus or uplands . Plains are one of

602-538: A few instances, deserts and rainforests may also be considered plains. Plains in many areas are important for agriculture because where the soils were deposited as sediments they may be deep and fertile , and the flatness facilitates mechanization of crop production; or because they support grasslands which provide good grazing for livestock . The types of depositional plains include: Erosional plains have been leveled by various agents of denudation such as running water, rivers, wind and glacier which wear out

688-601: A gradual transition, this rainfall line may be taken to divide the drier plains from the moister prairies. However, in Canada the eastern boundary of the plains is well defined by the presence of the Canadian Shield to the northeast. The plains (within the United States) may be described in northern, intermediate, central and southern sections, in relation to certain peculiar features. In Canada, no such division

774-520: A large importance in Earth's history as it saw the Cambrian explosion and Permian extinction . When global sea level rose and continents became partially submerged, the oceans had an explosion of complex life, which was the first time an event like this occurred on Earth. However, the center of Laurentia remained above sea level and as the continent moved east towards other supercontinents like Gondwana ,

860-578: A region of human geography , referring to the Plains Indians or the Plains states . In Canada the term is rarely used; Natural Resources Canada , the government department responsible for official mapping, treats the Interior Plains as one unit consisting of several related plateaus and plains. There is no region referred to as the "Great Plains" in the Atlas of Canada . In terms of human geography,

946-593: A west-northwest direction in what is now Oklahoma and Texas which is now known as the De Soto Trail. The Spanish thought that the Great Plains were the location of the mythological Quivira and Cíbola , a place said to be rich in gold. People in the southwest began to acquire horses in the 16th century by trading or stealing them from Spanish colonists in New Mexico. As horse culture moved northward,

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1032-403: Is about 500 mi (800 km) east to west and 2,000 mi (3,200 km) north to south. Much of the region was home to American bison herds until they were hunted to near extinction during the mid/late-19th century. It has an area of approximately 500,000 sq mi (1,300,000 km). Current thinking regarding the geographic boundaries of the Great Plains is shown by this map at

1118-556: Is also the ecoregion of the Great Plains or alternatively the western portion of the Great Plains. The Great Plains lie across both the Central United States and Western Canada , encompassing: The term "Great Plains" is used in the United States to describe a sub-section of the even more vast Interior Plains physiographic division, which covers much of the interior of North America. It also has currency as

1204-525: Is extraordinarily smooth. It is very dry, except for occasional shallow and temporary water sheets after rains. Llano is separated from the plains on the north by the mature consequent valley of the Canadian River , and from the mountains on the west by the broad and probably mature valley of the Pecos River . On the east, it is strongly undercut by the retrogressive erosion of the headwaters of

1290-624: Is from erosion of the newly formed Rocky Mountains as well as continued erosion from Appalachia. In general, Rocky Mountain sediment is deposited on the plains west of the Mississippi River, and Appalachian sediment is deposited to the east of the Mississippi River. 2.6 million years ago at the start of the Pleistocene Epoch , the Laurentide Ice Sheet began to spread southwards to cover North America down to

1376-416: Is included under this classification, which sustains nearly 50 percent of all United States beef cattle. In Canada, provinces located within the Interior Plains produce nearly 60 percent of all beef cattle. Much of the land in the Interior Plains is used for agriculture . In the year 2000, 43.8 percent of the Great Plains portion of the Interior Plains were used for agriculture. By far, wheat comprises

1462-506: Is peculiarly elaborate. Known as the Badlands , it is a minutely dissected form with a relief of a few hundred feet. This is due to several causes: The central section of the Great Plains, between latitudes 42° and 36° , occupying eastern Colorado and western Kansas , is mostly a dissected fluviatile plain. That is, this section was once smoothly covered with a gently sloping plain of gravel and sand that had been spread far forward on

1548-455: Is used: the climatic and vegetation regions are more impactful on human settlement than mere topography, and therefore the region is split into (from north to south), the taiga plains, boreal plains , aspen parkland , and prairie ecoregion regions. The northern section of the Great Plains, north of latitude 44° , includes eastern Montana , eastern Wyoming , most of North Dakota and South Dakota , southwestern Minnesota and portions of

1634-559: The American burying beetle (Nicrophorus americus), Salt Creek Tiger Beetle (Cinidela nevadica lincolniana), Great Plains Giant Tiger Beetle (Amblycheila chylindriformis), Microstylum morosum , Bean leaf beetle (Cerotoma trifurcata), Great Plains Camel Cricket (Daihinia brevipes), and the Great plains spittlebug (Lepyronia gibbosa). Some species in the Great plains have gone extinct in

1720-631: The Appalachian Mountains began to form around 400 MYA. This coincided with the formation of Pangea around 300 MYA, when the Appalachians were at their peak height. The central plains of Laurentia were subjected to deposition of eroded sediment from these mountains. The oldest sediments from this period are felsic igneous rocks and granite that have since been metamorphosed, while the younger sediments are made up of sandstone , shale , limestone , and coal . Sediments deposited in

1806-591: The Arikara , Mandan , Pawnee , and Wichita . Wars with the Ojibwe and Cree peoples pushed the Lakota (Teton Sioux) west onto the Great Plains in the mid- to late-17th century. The Shoshone originated in the western Great Basin and spread north and east into present-day Idaho and Wyoming. By 1500, some Eastern Shoshone had crossed the Rocky Mountains into the Great Plains. After 1750, warfare and pressure from

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1892-834: The Boreal Plains and Taiga Plains east of the Mackenzie and Richardson Mountains ; while in the United States , it includes the Great Plains of the West / Midwest and the tallgrass prairie region to the south of the Great Lakes extending east to the Appalachian Plateau region. A series of tectonic plate collisions in the crust that formed the center of the North American continent laid

1978-824: The Department of the Interior . In contrast, U.S. Forest Service , an agency of the U. S. Department of Agriculture , administers the National Forests and National Grasslands, under a multiple-use concept. By law, the U.S. Forest Service must consider all resources, with no single resource emphasized to the detriment of others, including water, soil, grazing, timber harvesting, and minerals (mining and drilling), as well as recreation and conservation of fish and wildlife. Each individual state also administers state lands, typically smaller areas, for various purposes including conservation and recreation. Grasslands are among

2064-684: The Dust Bowl . On May 12, 1934, alone, an estimated 200 million tons of wind-eroded topsoil were transported to the Atlantic Ocean. In response to the rapid aeolian erosion, soil preservation methods were implemented. In the years following the Dust Bowl, 18,500 miles (29,800 km) of shelterbelt were planted by the Works Progress Administration to reduce wind intensity. Grassland and shrubland make up

2150-904: The Great Plains toad ( Anaxyrus cognatus ), plains leopard frog ( Lithobates blairi ), and plains spadefoot toad ( Spea bombifrons ). Some species predominately associated with various river basins in the Great Plains include sturgeon chub ( Macrhybopsis gelida ), peppered chub ( Macrhybopsis tetranema ), prairie chub ( Macrhybopsis australis ), western silvery minnow ( Hybognathus argyritis ), plains minnow ( Hybognathus placitus ), smalleye shiner ( Notropis buccula ), Arkansas River shiner ( Notropis girardi ), Red River shiner ( Notropis bairdi ), Topeka shiner ( Notropis topeka ), plains topminnow ( Fundulus sciadicus ), plains killifish ( Fundulus zebrinus ), Red River pupfish ( Cyprinodon rubrofluviatilis ), and Arkansas darter ( Etheostoma cragini ). The great plains also has many invertebrate species living here both alive and extinct such as

2236-523: The Gulf of Mexico and covered almost all the interior plains west of the current boundary of the Mississippi River . Limestone-shale couplets, as well as carbonate layers, are commonly found in sedimentary deposits from this inland sea. Towards the end of this period, the inland seas began to drain due to uplift from the formation of the Rocky Mountains . The Laramide Orogeny event was when

2322-529: The Pleistocene epoch . The Nebraska Sand Dunes are an example of the sand and loess during the epoch. These dunes were formed during the Pleistocene by Northwesterly winds depositing alluvial silt and sand. That loess is so prevalent in the Interior Plains is evidence of significant aeolian erosion, as deposits are generally accumulations of wind-blown dust. Following World War I , wheat farming in

2408-432: The "Great Plains" as an ecoregion synonymous with predominant prairies and grasslands rather than as physiographic region defined by topography. The Great Plains ecoregion includes five sub-regions: Temperate Prairies, West-Central Semi-Arid Prairies, South-Central Semi-Arid Prairies, Texas Louisiana Coastal Plains, and Tamaulipas-Texas Semi-Arid Plain, which overlap or expand upon other Great Plains designations. The region

2494-555: The Blackfoot, Crow, Lakota, Cheyenne, and Arapaho pushed Eastern Shoshone south and westward. Some of them moved as far south as Texas, emerging as the Comanche by 1700. The first known contact between Europeans and Indians in the Great Plains occurred in what is now Texas, Kansas, and Nebraska from 1540 to 1542 with the arrival of Francisco Vázquez de Coronado , a Spanish conquistador. In that same period, Hernando de Soto crossed

2580-503: The Canadian provinces including southeastern Alberta , southern Saskatchewan and southwestern Manitoba . The strata here are Cretaceous or early Tertiary , lying nearly horizontal. The surface is shown to be a plain of degradation by a gradual ascent here and there to the crest of a ragged escarpment, the escarpment-remnant of a resistant stratum. There are also the occasional lava -capped mesas and dike formed ridges, surmounting

2666-461: The Center for Great Plains Studies, University of Nebraska–Lincoln . This definition, however, is primarily ecological, not physiographic. The Boreal Plains of Western Canada are physiographically the same, but differentiated by their tundra and forest (rather than grassland) appearance. The term "Great Plains", for the region west of about the 96th meridian west and east of the Rocky Mountains ,

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2752-556: The Comanche were among the first to commit to a fully mounted nomadic lifestyle. This occurred by the 1730s, when they had acquired enough horses to put all their people on horseback. The real beginning of the horse culture of the plains began with the Pueblo Revolt of 1680 in New Mexico and the capture of thousands of horses and other livestock. In 1683 a Spanish expedition into Texas found horses among Native people. In 1690,

2838-740: The Earth's surface. Interior Plains The Interior Plains is a vast physiographic region that spreads across the Laurentian craton of central North America , extending along the east flank of the Rocky Mountains from the Gulf Coast region to the Arctic Beaufort Sea . In Canada , it encompasses the Canadian Prairies separating the Canadian Rockies from the Canadian Shield , as well as

2924-551: The Great Plains and into the valleys and lower elevations of the eastern Rocky Mountains and portions of the American southwest . Other snakes include the plains hog-nosed snake ( Heterodon nasicus ), western milksnake ( Lampropeltis gentilis ), great plains ratsnake ( Pantherophis emoryi ), bullsnake ( Pituophis catenifer sayi ), plains black-headed snake ( Tantilla nigriceps ), plains gartersnake ( Thamnophis radix ), and lined snake ( Tropidoclonion lineatum ). Reptile diversity increases significantly in southern regions of

3010-627: The Great Plains and that included trade networks west to the Rocky Mountains. Mississippians settled the Great Plains at sites now in Oklahoma and South Dakota . Siouan language speakers may have originated in the lower Mississippi River region. They were agriculturalists and may have been part of the Mound Builder civilization during the 9th–12th centuries. Pressure from other Indian tribes, themselves driven west and south by

3096-586: The Great Plains include National Parks and National Monuments, administers by the National Park Service with the responsibility of preserving ecological and historical places and making them available to the public. The U.S. Fish & Wildlife Service manages the National Wildlife Refuges, with the primary responsibility of conserving and protecting fish, wildlife, plants, and habitat in the public trust. Both are agencies of

3182-475: The Great Plains include the swift fox ( Vulpes velox ) and the endangered black-footed ferret ( Mustela nigripes ). The lesser prairie chicken ( Tympanuchus pallidicinctus ) is endemic to the Great Plains and the distribution of the greater prairie chicken ( Tympanuchus cupido ) predominantly occurs in the region, although the latter historically ranged further eastward. The Harris's sparrow ( Zonotrichia querula ) spends winter months in southern areas of

3268-511: The Great Plains is the most tornado active area in the world and is sometimes referred to as Tornado Alley . The Great Plains are part of the floristic North American Prairies province , which extends from the Rocky Mountains to the Appalachians . Although the American bison ( Bison bison ) historically ranged throughout much of North America (from New York to Oregon and Canada to northern Mexico), they are strongly associated with

3354-751: The Great Plains where they once roamed in immense herds. Pronghorn ( Antilocapra americana ) range into western areas of the region. The black-tailed prairie dog ( Cynomys ludovicianus ) is another iconic species among several rodents that are linked to the region including the thirteen-lined ground squirrel ( Ictidomys tridecemlineatus ), spotted ground squirrel ( Xerospermophilus spilosoma ), Franklin's ground squirrel ( Poliocitellus franklinii ), plains pocket gopher ( Geomys bursarius ), hispid pocket mouse ( Chaetodipus hispidus ), olive-backed pocket mouse ( Perognathus fasciatus ), plains pocket mouse ( Perognathus flavescens ), and plains harvest mouse ( Reithrodontomys montanus ), Two carnivores associated with

3440-487: The Great Plains. The ornate box turtle ( Terrapene ornata ) and great plains skink ( Plestiodon obsoletus ) occur in southern areas. Although few salamanders are strongly associated with region, the western tiger salamander ( Ambystoma mavortium ) ranges through much of the Great Plains and the Rocky Mountains, as does the Rocky Mountain toad ( Anaxyrus w. woodhousi ). Other anurans related to region include

3526-503: The High Plains) is periodically subjected to extended periods of drought ; high winds in the region may then generate devastating dust storms . The eastern Great Plains near the eastern boundary falls in the humid subtropical climate zone in the southern areas, and the northern and central areas fall in the humid continental climate . Many thunderstorms occur in the plains in the spring through summer. The southeastern portion of

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3612-508: The Interior Plains. Civil engineering projects have altered the fluvial geomorphology of the Interior Plains. Normal sediment transport by river and channel systems is interrupted by river-blocking structures such as dams and flow regulators. Before 1900, the estimated annual sediment transport by the Mississippi River to the Gulf of Mexico was 400 million tons. However, in the early 20th century, engineering projects including dams were created on

3698-668: The Laurentide. During the retreat, the Laurentide gouged and filled the glacial paleolake McConnell in northern Canada. As the region uplifted and rebounded isostatically from the mass of the ice sheet, paleolake McConnell was split into Great Slave Lake and Great Bear Lake. Great Slave Lake's basin formed under the 4-kilometer thick Keewatin Dome that today is the deepest lake in North America. A vast amount of smaller lakes were formed as well and serve an integral part of ethos in

3784-482: The Missouri River, meander cutoffs, river training, bank revetments, and soil erosion control have reduced the annual transport rate to between 100 and 150 million tons of sediment per year. The artificial structures trap suspended sediment from traveling as it would in an un-engineered river. While average annual temperatures vary significantly between the northern and southern portions of the Interior Plains,

3870-634: The North American continent and extended from northern Canada to the interior plains, covering parts of Wyoming , Montana , North Dakota , and South Dakota . Coquina and sandstone layers from marine deposition were deposited on top of rock layers from the Paleozoic Era . During the Cretaceous period , another inland sea called the Western Interior Seaway was formed. This body of water extended from present-day Alaska to

3956-650: The Red, Brazos, and Colorado rivers of Texas and presents a ragged escarpment approximately 500 to 800 ft (150 to 240 m) high, overlooking the central denuded area of that state. There, between the Brazos and Colorado rivers, occurs a series of isolated outliers capped by limestone that underlies both the Llano Uplift on the west and the Grand Prairies escarpment on the east. The southern and narrow part of

4042-415: The United States, and the two governments each use a different hierarchical system to classify their portions. In Canada, the Interior Plains makes up one of seven physiographic areas included in the highest level of classification - defined as a "region" in that country. In the United States it is one of eight physiographic areas (of the contiguous 48 states) included in the highest classification, defined as

4128-593: The area of the ancient Great Plains for thousands to millions of years. The vast majority of these animals became extinct in North America at the end of the Pleistocene (around 13,000 years ago). A number of significant fossil sites are located in the Great Plains including Agate Fossil Beds National Monument ( Nebraska ), Ashfall Fossil Beds ( Nebraska ), Clayton Lake State Park ( New Mexico ), Dinosaur Valley State Park ( Texas ), Hudson-Meng Bison Kill (Nebraska), Makoshika State Park (Montana), and The Mammoth Site ( South Dakota ). Public and protected lands in

4214-471: The central section, it is for the most part a dissected fluviatile plain. However, the lower lands which surround it on all sides place it in such strong relief that it stands up as a table-land, known from the time of Mexican occupation as the Llano Estacado . It measures roughly 150 mi (240 km) east-west and 400 mi (640 km) north-south. It is of very irregular outline, narrowing to

4300-415: The climate is characterized by susceptibility to droughts due to generally low annual precipitation. Due to a warm climate and evapotranspiration rates surpassing precipitation rates, the southern Interior Plains are highly susceptible to droughts and soil erosion . A significant feature of aeolian erosion in the Interior Plains is the ubiquitous loess deposits. The deposits were placed by winds during

4386-529: The encroachment of European settlers as well as economic incentives such as the fur trade, alongside the arrival of the horse and firearms from Europe pushed multiple tribes onto the Great Plains. Among those to have lived on the Great Plains were the Blackfoot , Crow , Sioux , Cheyenne , Arapaho , Comanche , and others. Eastern portions of the Great Plains were inhabited by tribes who lived at Etzanoa and in semi-permanent villages of earth lodges, such as

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4472-423: The fertile loess soil of the Interior Plains swelled. The expansion of farmland eliminated many prairies containing soil-stabilizing grasses. While droughts in the region were common, during the following drought, aeolian soil erosion was exacerbated by the reduced soil-holding prairie grasses. Dust storms eroded hundreds of millions of tons of topsoil, causing dust storms for months in the historical region known as

4558-433: The general level by 500 ft (150 m) or more and manifestly demonstrating the widespread erosion of the surrounding plains. All these reliefs are more plentiful towards the mountains in central Montana. The peneplain is no longer in the cycle of erosion that witnessed its production. It appears to have suffered a regional uplift or increase in elevation, for the upper Missouri River and its branches no longer flow on

4644-684: The great plains like the Rocky Mountain Locust (Melanoplus spretus). During the Cretaceous Period (145–66 million years ago), the Great Plains were covered by a shallow inland sea called the Western Interior Seaway . However, during the Late Cretaceous to the Paleocene (65–55 million years ago), the seaway had begun to recede, leaving behind thick marine deposits and a relatively flat terrain which

4730-558: The groundwork for the modern-day interior plains. Mountain building and erosion around the plains as well as flooding from inland seas provided sediments that make up the rock strata of the interior plains. Between 2.0 and 1.8 billion years ago the Hearne-Rae, Superior, and Wyoming cratons were sutured together to form the North American craton, Laurentia , in an event called the Trans-Hudson Orogeny (THO). This event

4816-522: The interior plains are in the Black Hills of South Dakota . The sediments that formed the Black Hills were granite and different types of igneous rocks , which make up the basement of bedrock in central North America. However, much of the Black Hills sediment has been metamorphosed and deformed, so it is uncertain what the conditions were like at the time of their formation. This period has

4902-581: The interior plains from this era are currently buried deep beneath the surface where they are difficult to study. Around 220 MYA, the supercontinent Pangea broke apart, and the North American continent began to move west and isolate itself. For much of this period the interior plains were covered by inland seas. During the Jurassic period , the Sundance Sea formed along the western coast of

4988-501: The largest group. They rise like a large island from the sea, occupying an oval area of about 100 mi (160 km) north-south by 50 mi (80 km) east-west. At Black Elk Peak , they reach an altitude of 7,216 ft (2,199 m) and have an effective relief over the plains of 2,000 or 3,000 ft (610 or 910 m) This mountain mass is of flat-arched, dome-like structure, now well dissected by radiating consequent streams. The weaker uppermost strata have been eroded down to

5074-504: The largest portion of the Interior Plains within the United States, at 44.4 percent. The western margin is mainly shortgrass prairie dominated by blue grama and buffalograss . Prairies on the eastern side of the Interior Plains are dominated by tall grass varieties including big bluestem and switchgrass . The two regions are separated by mixed-grass prairie, which contains both short and long grass varieties as well as little bluestem and western wheatgrass . Land used for cattle-grazing

5160-625: The largest portion of the agricultural yield in region; combined, wheat exports from the Interior Plains make up more than half of the world's exports. Other significant crops produced in the region include barley , corn , cotton , sorghum , soybeans , and canola , which is particularly important to Canadian exports. Other sources comprise much smaller portions of the land. In decreasing percentage, forests make up 5.8%, wetland makes up 1.6%, developed land makes up 1.5%, barren land makes up .6%, and land used for mining makes up .1%. The Interior Plains physiographic area stretches across Canada and

5246-467: The least protected biomes. Humans have converted much of the prairies for agricultural purposes or to create pastures. Several of the protected lands in the region are centered around aberrant and uncharacteristic features of the region, such as mountains, outcrops, and canyons (e.g. Devil's Tower National Monument , Wind Cave National Park , Scotts Bluff National Monument ), and as splendid and worthy as they are, they are not primarily focused on conserving

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5332-425: The level of the plains where their upturned edges are evenly truncated. The next following harder strata have been sufficiently eroded to disclose the core of underlying igneous and metamorphic crystalline rocks in about half of the domed area. In the intermediate section of the plains, between latitudes 44° and 42° , including southern South Dakota and northern Nebraska , the erosion of certain large districts

5418-424: The line that divides the Great Plains into an area that receives 20 in (510 mm) or more of rainfall per year and an area that receives less than 20 in (510 mm). In this context, the High Plains, as well as Southern Alberta , south-western Saskatchewan and Eastern Montana are mainly semi arid steppe land and are generally characterised by rangeland or marginal farmland . The region (especially

5504-402: The major landforms on earth, where they are present on all continents, and cover more than one-third of the world's land area. In a valley, a plain is enclosed on two sides, but in other cases a plain may be delineated by a complete or partial ring of hills, by mountains, or by cliffs . Where a geological region contains more than one plain, they may be connected by a pass (sometimes termed

5590-569: The more common "prairie". The Great Plains are the westernmost portion of the vast North American Interior Plains , which extend east to the Appalachian Plateau . The United States Geological Survey divides the Great Plains in the United States into ten physiographic subdivisions: Further to this can be added Canadian physiographic sub-regions such as the Alberta Plain, Cypress Hills , Manitoba Escarpment (eastward), Manitoba Plain, Missouri Coteau (shared), Rocky Mountain Foothills (eastward), and Saskatchewan Plain. The Great Plains consist of

5676-441: The mountains, the local relief is generally small. The semi-arid climate excludes tree growth and opens far-reaching views. The plains are by no means a simple unit. They are of diverse structure and of various stages of erosional development. They are occasionally interrupted by buttes and escarpments . They are frequently broken by valleys. Yet on the whole, a broadly extended surface of moderate relief so often prevails that

5762-435: The name, Great Plains, for the region as a whole is well-deserved. The western boundary of the plains is usually well-defined by the abrupt ascent of the mountains. The eastern boundary of the plains (in the United States) is more climatic than topographic . The line of 20 in (510 mm) of annual rainfall trends a little east of northward near the 97th meridian. If a boundary must be drawn where nature presents only

5848-491: The northern Great Plains on the western side of the Interior Plains and down into most of Minnesota and Wisconsin. The Laurentide Ice Sheet had a large influence on the morphology of the Interior Plains during the end of the Pleistocene. During the retreat, the Laurentide scoured numerous pockets of sediment. Upon the plate's melting, those pockets were filled, resulting in the kettle lakes. The Great Lakes and both Great Slave Lake and Great Bear Lake of Canada were formed by

5934-430: The plains and prairies. United States: Canada: the Great Plains biome is found to be at the brink of collapse due to woody plant encroachment , with 62% of Northern American grassland lost to date. The first Peoples ( Paleo-Indians ) arrived on the Great Plains thousands of years ago. The introduction of corn around 800 CE allowed the development of the mound-building Mississippian culture along rivers that crossed

6020-646: The region. Other species migrate from the south in the spring and spend their breeding season on the plains, including the white-faced ibis ( Plegadis chihi ), mountain plover ( Charadrius montanus ), marbled godwit ( Limosa fedoa ), Sprague's pipit ( Anthus spragueii ), Cassin's sparrow ( Peucaea cassinii ), Baird's sparrow ( Centronyx bairdii ), lark bunting ( Calamospiza melanocorys ), chestnut-collared longspur ( Calcarius ornatus ), thick-billed longspur or McCown's longspur ( Rhynchophanes mccownii ), and dickcissel ( Spiza americana ). The prairie rattlesnake ( Crotalus viridis ) ranges throughout much of

6106-473: The river from a better graded preglacial valley by the Pleistocene ice sheet . Here, the ice sheet overspread the plains from the moderately elevated Canadian highlands far on the north-east, instead of from the much higher mountains nearby on the west. The present altitude of the plains near the mountain base is 4,000 ft (1,200 m). The northern plains are interrupted by several small mountain areas. The Black Hills, chiefly in western South Dakota, are

6192-400: The rugged surface and smoothens them. Plain resulting from the action of these agents of denudation are called peneplains (almost plain) while plains formed from wind action are called pediplains . Structural plains are relatively undisturbed horizontal surfaces of the Earth. They are structurally depressed areas of the world that make up some of the most extensive natural lowlands on

6278-564: The seaway had once occupied. During the Cenozoic era , specifically about 25 million years ago during the Miocene and Pliocene epochs, the continental climate became favorable to the evolution of grasslands. Existing forest biomes declined and grasslands became much more widespread. The grasslands provided a new niche for mammals, including many ungulates and glires , that switched from browsing diets to grazing diets. Traditionally,

6364-465: The south. Its altitude is 5,500 ft (1,700 m) at the highest western point, nearest the mountains whence its gravels were supplied. From there, it slopes southeastward at a decreasing rate, first about 12 ft (3.7 m), then about 7 ft/mi (1.3 m/km), to its eastern and southern borders, where it is 2,000 ft (610 m) in altitude. Like the High Plains farther north, it

6450-459: The southern section owes its smoothness to the deposition of imported gravels and sands upon a previously uneven surface by the action of aggrading rivers and their outgoing distributaries. The two sections are also alike in that residual eminences still here and there surmount the peneplain of the northern section, while the fluviatile plain of the central section completely buried the pre-existent relief. An exception to this statement must be made for

6536-415: The southwest, close to the mountains in southern Colorado, where some lava-capped mesas ( Mesa de Maya , Raton Mesa ) stand several thousand feet above the general plain level, and thus testify to the widespread erosion of this region before it was aggraded. The southern section of the Great Plains, between latitudes 35.5° and 25.5°, lies in western Texas , eastern New Mexico , and western Oklahoma . Like

6622-586: The spread of grasslands and the development of grazers have been strongly linked. However, an examination of mammalian teeth suggests that it is the open, gritty habitat and not the grass itself which is linked to diet changes in mammals, giving rise to the " grit, not grass " hypothesis. Paleontological finds in the area have yielded bones of mammoths , saber-toothed cats and other ancient animals, as well as dozens of other megafauna (large animals over 100 lb [45 kg]) – such as giant sloths , horses , mastodons , and American lion – that dominated

6708-599: The subdued forms of the Wichita Mountains in Oklahoma , the westernmost member of the Ouachita system. The term "Western Plains" is used to describe the ecoregion of the Great Plains, or alternatively the western portion of the Great Plains. In general, the Great Plains have a wide range of weather, with very cold and harsh winters and very hot and humid summers. Wind speeds are often very high, especially in winter. The 100th meridian roughly corresponds with

6794-464: The surface of the plain, but in well graded, maturely opened valleys, several hundred feet below the general level. A significant exception to the rule of mature valleys occurs, however, in the case of the Missouri, the largest river, which is broken by several falls on hard sandstones about 50 mi (80 km) east of the mountains. This peculiar feature is explained as the result of displacement of

6880-477: The surrounding regions. For example, Minnesota is often referred to as “the Land of 10,000 Lakes” due to the number and widespread recreational use of the state's lakes. Much of the loess distributed within the Interior Plains has its origin in glaciers. In glaciated conditions, sand and silt-laden meltwater originating from alpine glaciers in the Rocky Mountains generated alluvial deposits at their base. This alluvium

6966-590: The table-land, called the Edwards Plateau , is more dissected than the rest, and falls off to the south in a frayed-out fault scarp. This scarp overlooks the coastal plain of the Rio Grande embayment . The central denuded area, east of the Llano, resembles the east-central section of the plains in exposing older rocks. Between these two similar areas, in the space limited by the Canadian and Red Rivers, rise

7052-462: The term prairie is more commonly used in Canada, and the region is known as the Canadian Prairies , prairie provinces or simply "the prairies". The North American Environmental Atlas , produced by the Commission for Environmental Cooperation , a North American Free Trade Agreement (NAFTA) agency composed of the geographical agencies of the Mexican, American, and Canadian governments, uses

7138-727: The western Cordillera was formed due to the flat-slab subduction of the Farallon Plate under the North American Plate. This created the frontal range of the Rockies from Montana through New Mexico . The outcrops seen at the surface of the Rockies are made up of sandstone, granite, and limestone; as well as metamorphic rocks uplifted from the Proterozoic Period. The interior plains have remained relatively flat during this period and recent sedimentation

7224-737: Was like the Indian Plate colliding with the Eurasian Plate , which formed the Himalayas . After initial collisions during the THO, tectonic activity at the edges of the four main cratons sparked mountain building . The interior of Laurentia remained relatively flat and became a basin for eroded sediment from mountains at the beginning of the current time period, the Phanerozoic Eon . The only remaining outcrops from this orogeny in

7310-574: Was not generally used before the early 20th century. Nevin Fenneman's 1916 study Physiographic Subdivision of the United States brought the term Great Plains into more widespread usage. Before that the region was almost invariably called the High Plains, in contrast to the lower Prairie Plains of the Midwestern states . Today the term " High Plains " is used for a subregion of the Great Plains. The term still remains little-used in Canada compared to

7396-404: Was then distributed throughout the Interior Plains by strong winds. Sediment transport within the Interior Plains occurs primarily by aeolian and fluvial processes . Due to climate change, the average temperature of the Interior Plains is increasing and the region is becoming more arid. Because of the increase in rainstorm intensity, rain-driven erosion will grow as a factor of soil erosion in

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