Interior Plains

Source: Wikipedia, the free encyclopedia.

The Interior Plains are highlighted in red.

The Interior Plains is a vast

Midwest and the tallgrass prairie region to the south of the Great Lakes extending east to the Appalachian Plateau region.[1]

Geologic history

A series of tectonic plate collisions in the crust that formed the center of the North American continent laid 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.

Proterozoic Eon (2500 to 539 million years ago)

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,

metamorphosed and deformed, so it is uncertain what the conditions were like at the time of their formation.[2]

Paleozoic Era (539 to 252 million years ago)

This period has a large importance in Earth’s history as it saw the

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.[5] 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 the interior plains from this era are currently buried deep beneath the surface where they are difficult to study.[6]

Mesozoic Era (252 to 66 million years ago)

Around 220 MYA, the supercontinent Pangea broke apart, and the

Cretaceous period, another inland sea called the Western Interior Seaway was formed. This body of water extended from present-day Alaska to 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.[9] Towards the end of this period, the inland seas began to drain due to uplift from the formation of the Rocky Mountains.[7]

Cenozoic Era (66 million years ago to Present Day)

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 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.[10]

Glacial history

2.6 million years ago at the start of the

glacial paleolake McConnell in northern Canada.[14] 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.[15] A vast amount of smaller lakes were formed as well and serve an integral part of ethos in the surrounding regions. For example, Minnesota is often referred to as “the Land of 10,000 Lakes”[16]
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 was then distributed throughout the Interior Plains by strong winds.[11]

Sediment transport

Sediment transport within the Interior Plains occurs primarily by

fluvial processes.[17] 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 the Interior Plains.[18]

Fluvial processes

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.[19] However, in the early 20th century, engineering projects including dams were created on the Missouri River, meander cutoffs, river training, bank revetments, and soil erosion control have reduced the annual transport rate to between 100-150 million tons of sediment per year. The artificial structures trap suspended sediment from traveling as it would in an un-engineered river.[17]

Aeolian processes

While average annual temperatures vary significantly between the northern and southern portions of the Interior Plains, the climate is characterized by susceptibility to droughts due to generally low annual precipitation.[20]

Due to a warm climate and

Pleistocene epoch.[21] The Nebraska Sand Dunes are an example of the sand and loess during the epoch.[22] 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.[23]

Loess Hills in western Iowa along I-80.

Following World War I, wheat farming in the fertile loess soil of the Interior Plains swelled. The expansion of farmland eliminated many prairies containing soil-stabilizing grasses.[24] While droughts in the region were common,[20] 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 the Dust Bowl. On May 12, 1934 alone, an estimated 200 million tons of wind-eroded topsoil were transported to the Atlantic Ocean.[24]

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.[25]

Current land use

western wheatgrass.[27] Land used for cattle-grazing is included under this classification, which sustains nearly 50 percent of all United States beef cattle.[28]

In Canada, provinces located within the Interior Plains produce nearly 60 percent of all beef cattle.[28]

Much of the land in the Interior Plains is used for

canola, which is particularly important to Canadian exports.[28]

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%.[26]

Physiography

Interior Plains physiographic areas defined by the United States and Canada.

The Interior Plains physiographic area stretches across Canada and 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 a "division" there.[29][30]

Interior Plains in Canada

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 the tertiary level (called "division" in Canada) is used in the mapping data.[31]

The following list is of the 14 physiographic divisions in the Interior Plains of Canada. Further information can be found at https://atlas.gc.ca/phys/en/index.html

  • Alberta Plain
  • Alberta Plateau
  • Anderson Plain
  • Colville Hills
  • Cypress Hills
  • Fort Nelson Lowland
  • Great Bear Plain
  • Great Slave Plain
  • Horton Plain
  • Manitoba Plain
  • Peace River Lowland
  • Peel Plain
  • Peel Plateau
  • Saskatchewan Plain

Interior Plains in the United States

The following is a breakdown of the secondary (provinces), and tertiary (sections) physiographic areas of the Interior Plains portion in the United States:[32]

Central Lowland

Great Plains

Interior Low Plateau

See also

References

  1. Canadian Encyclopedia
    . Retrieved June 2, 2019. Interior Plains
  2. ^ a b "North America". Britannica. Britannica. Retrieved November 21, 2020.
  3. doi:10.1029/2005TC001907
    . Retrieved November 21, 2020.
  4. ^ Robison, Richard A.; Crick, Rex E. "Paleozoic Era". Britannica. Encyclopedia Britannica. Retrieved November 23, 2020.
  5. ^ "The Blue Ridge and Appalachian Mountains – A Geologic History". Blue Ridge Dream. Living the Blue Ridge Dream. Retrieved November 23, 2020.
  6. ^ Dykeman, Wilma. "Appalachian Mountains". Britannica. Encyclopedia Britannica. Retrieved November 23, 2020.
  7. ^ a b Slattery, Joshua S.; Cobban, William A.; McKinney, Kevin C.; Harries, Peter J.; Sandness, Ashley L. "EARLY CRETACEOUS TO PALEOCENE PALEOGEOGRAPHY OF THE WESTERN INTERIOR SEAWAY: THE INTERACTION OF EUSTASY AND TECTONISM". In Marron Bingle-Davis (ed.). Wyoming Geological Association 68th Annual Field Conference. Vol. 68. Wyoming Geological Association. Retrieved November 23, 2020 – via ResearchGate.
  8. doi:10.1111/j.1365-3091.1988.tb01248.x
    . Retrieved November 23, 2020.
  9. doi:10.1130/0016-7606(1994)106<0892:COBCCT>2.3.CO;2
    . Retrieved November 23, 2020.
  10. ISBN 0813711517
    . Retrieved November 23, 2020.
  11. ^ a b Wayne, William J. "Glaciation". Encyclopedia of the Great Plains.
  12. ^ "Great Lakes Ecoregion". National Oceanic and Atmospheric Administration. Retrieved November 15, 2020.
  13. doi:10.1139/f75-234
    .
  14. doi:10.1016/0277-3791(94)90004-3
    .
  15. doi:10.1130/G24628A.1
    .
  16. ^ "MNLakes". MNLakes. Retrieved November 20, 2020.
  17. ^
    hdl:11681/37073
    .
  18. doi:10.1016/j.wace.2015.06.002
    .
  19. doi:10.1002/hyp.7477
    .
  20. ^ a b c Shafer, Mark; Ojima, Dennis. "Great Plains". National Climate Assessment. Retrieved November 12, 2020.
  21. doi:10.1006/qres.1999.2090
    .
  22. ^ "Sand Hills, Nebraska". NASA. Retrieved November 18, 2020.
  23. doi:10.1016/0277-3791(95)00047-X
    .
  24. ^ a b Hurt, R. Douglas. "Dust Bowl". Encyclopedia of the Great Plains. Retrieved November 3, 2020.
  25. ^ Brandle, James R. "Sheltebelts". Encyclopedia of the Great Plains. Retrieved November 3, 2020.
  26. ^
    doi:10.3133/pp1794B
    .
  27. ^ Vinton, Mary Ann. "Grasses". Encyclopedia of the Great Plains.
  28. ^ a b c d Hudson, John C. "Agriculture". Encyclopedia of the Great Plains. Retrieved November 11, 2020.
  29. ^ "Physiographic divisions of the conterminous U. S. - ScienceBase-Catalog". www.sciencebase.gov. Retrieved November 12, 2023.
  30. ^ Secretariat, Treasury Board of Canada. "Physiographic Regions of Canada - Open Government Portal". open.canada.ca. Retrieved November 12, 2023.
  31. ^ Secretariat, Treasury Board of Canada. "Physiographic Regions of Canada - Open Government Portal". open.canada.ca. Retrieved November 16, 2023.
  32. ^ "USGS Science Data Catalog". data.usgs.gov. Retrieved November 16, 2023.

External links

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