Central Lowland

a plains region in the interior of North America, in the USA and Canada. The Central Lowland is bounded on the southeast and northeast by the Appalachian Mountains and the Laurentian Upland; in the west it adjoins the Great Plains, and it extends south to the Gulf Coastal Plain. The region has elevations of 150–500 m.

The Central Lowland corresponds to the southern North American Shield, whose crystalline basement is overlain by horizontal and slightly dipping strata of Paleozoic shales and limestones. It contains the coal deposits of the interior coalfields and deposits of petroleum and salt. The Ozark Plateaus have deposits of lead and zinc (at St. Joseph) and barite. The Central Lowland’s various plains include hilly-morainal, outwash, and lake plains in the north. Morainal and loess plains that are deeply dissected by valleys are found in the central part, and elevated plains with typical erosion relief and karst formations, such as the Ozark Plateaus, are found in the south. Cuestas, such as the Niagara Escarpment, are located in the north; the Boston Mountains are located in the south. Most of the Central Lowland is drained by the river system of the Mississippi River basin. In the north is a group of large lakes formed by glacial erosion, including the Great Lakes and Lakes Winnipeg, Winnipegosis, and Manitoba.

The region has a temperate continental climate that becomes subtropical in the extreme south. The mean January temperature ranges from –20°C in the north to 4°C in the south. During the winter, freezes and thaws alternate frequently, and heavy snowstorms occur. The mean July temperature ranges from 18°C in the north to 25°C in the south. Annual precipitation varies from 400 mm in the northwest to 1,200 mm in the southeast. In the north, brown forest soils predominate; on these soils grow mixed forests of black and white spruce, pine, sugar and red maple, linden, and common hemlock and broadleaved forests of white and red oak and hickory. Chernozem-like soils formed in the south under the tall-grass prairies, which have virtually disappeared owing to the plowing under and settlement of the area. In the north, some forested areas still remain in uplands inconvenient for economic development. The most common mammals are rodents.

The Central Lowland is one of the most important agricultural regions of the United States and Canada, producing grain and livestock. More than 75 percent of the region is pasture and cropland. The large metropolitan areas of Chicago, Detroit, and Cleveland are located in the northeastern Central Lowland.