Physiographic regions of North America

Physiographic regions of North America
Name	Physiographic regions of North America
Caption	Continental-scale physiography
Location	North America
Highest point	Denali
Country	Canada; United States; Mexico; Greenland; Bermuda; Saint Pierre and Miquelon

Physiographic regions of North America Physiographic regions of North America are the large-scale spatial divisions that reflect the continent’s topography, geology, and geomorphic history across Canada, the United States, Mexico, Greenland, and adjacent islands such as Bermuda and Saint Pierre and Miquelon. These divisions integrate evidence from mountain systems like the Rocky Mountains, cratons such as the Canadian Shield, sedimentary basins like the Great Plains (United States), and coastal systems including the Gulf of Mexico and the Atlantic Ocean (North America). Classification schemes used by agencies including the United States Geological Survey and the Geological Survey of Canada inform land management in regions influenced by events such as the Laramide orogeny and the Sevier orogeny.

Overview and Definitions

Physiographic regions are defined by shared geomorphology, stratigraphy, structural history, and relief, applied by entities such as the United States Department of the Interior and the Natural Resources Canada for mapping from continental to local scale. Foundational concepts derive from work by figures like William Morris Davis and organizations including the American Geographical Society and the Royal Society of Canada, while standardization references include the North American continent frameworks used in publications by the United Nations Environment Programme. Common physiographic units include shields, platforms, folded belts, and volcanic arcs exemplified by areas mapped in the Atlas of Canada and the National Atlas of the United States.

Major Physiographic Divisions

Major divisions commonly recognized are the Laurentian Upland and Canadian Shield, the Interior Plains, the Cordillera, the Appalachian Mountains, the Arctic Archipelago, the Great Basin, and the Coastal Plains. Within these are provinces such as the Columbia Plateau, the Sierra Nevada, the Cascade Range, the Mexican Plateau, and the Yucatan Peninsula, each associated with mapped units used by the USGS and the Geological Survey of Canada.

Regional Descriptions and Characteristics

- The Canadian Shield and Laurentia craton exhibit exposed Precambrian basement with low relief and rich mineralization exploited historically by mining companies in regions like Sudbury Basin and Hudson Bay. - The Interior Plains host thick Phanerozoic sedimentary successions forming the Williston Basin, Western Canada Sedimentary Basin, and agricultural landscapes around Saskatchewan, Manitoba, Kansas, and Nebraska. - The Cordillera comprises the Rocky Mountains, Sierra Madre Occidental, and Sierra Madre Oriental, with active tectonics tied to the Pacific Plate, the North American Plate, and subduction zones near the Cascadia subduction zone and the Middle America Trench. - The Appalachian Mountains record Paleozoic orogenies including the Acadian orogeny and the Alleghanian orogeny, with folded strata exposed in regions like Newfoundland and Labrador, Pennsylvania, and North Carolina. - Coastal provinces such as the Gulf Coastal Plain and the Atlantic Coastal Plain feature Quaternary sediments, barrier islands like Long Island and Galveston Island, and estuaries including the Chesapeake Bay and Hudson River Estuary.

Geological History and Processes

North America’s physiography results from accretion, rifting, collision, and glaciation over billions of years, involving archaic episodes tied to supercontinents including Rodinia and Pangea. The assembly of Atlantic margins followed the Mesozoic rifting that opened the Atlantic Ocean (North America), while the western Cordillera formed via successive terrane accretion exemplified by the Insular Belt and the Klamath Mountains. Pleistocene glaciations sculpted features across Ontario, Quebec, Minnesota, and New England, producing landforms such as the Great Lakes, moraines like the Long Island moraine, and fjords in Labrador. Volcanism has generated provinces including the Columbia River Basalt Group, Yellowstone Caldera, and the volcanic arc of the Trans-Mexican Volcanic Belt.

Climate, Soils, and Ecosystems by Region

Climatic regimes from polar in Greenland and the Arctic Archipelago to tropical in the Yucatan Peninsula and Central America drive soil orders such as Gelisols in tundra and Mollisols under the Great Plains (United States), supporting ecosystems ranging from boreal forest in Alberta and Quebec to temperate rainforest in British Columbia and chaparral in California. Biomes correspond to physiographic controls on moisture and elevation, influencing species distributions across conservation areas like Banff National Park, Yellowstone National Park, Everglades National Park, and Sian Ka’an Biosphere Reserve.

Human Use and Landform Management

Human settlement and infrastructure concentrate in river valleys and coastal plains—examples include Mississippi River Delta ports, the St. Lawrence River corridor, and the Central Valley (California). Resource extraction targets regional geology: petroleum in the Permian Basin, coal in the Appalachian Basin, metals in the Canadian Shield, and groundwater in the Ogallala Aquifer. Management challenges involve coastal erosion at sites like New Orleans and Miami, land-use planning in rapidly urbanizing regions such as Greater Toronto Area and Mexico City, and hazard mitigation for earthquakes along the San Andreas Fault and volcanic risks at Popocatépetl.

Mapping, Classification Methods, and Controversies

Mapping approaches range from classical physiographic mapping by the USGS and Geological Survey of Canada to modern digital elevation models derived from NASA missions such as Landsat and Shuttle Radar Topography Mission. Classification disputes concern the delineation of provinces like the boundary between the Interior Plains and the Canadian Shield, the extent of the Cordillera across Mexico, and the treatment of submerged continental margins including the Atlantic continental shelf. Debates also arise over anthropogenic alteration of landforms through projects like the Saint Lawrence Seaway and the environmental effects of extractive industries in areas governed by treaties such as the Treaty of Guadalupe Hidalgo.

Category:Physiography of North America