A part of the vast Central Lowlands of North America, the Osage Plains incorporate western Missouri, southeastern Kansas, central Oklahoma, and north-central Texas. The area is sometimes called the Lower Plains, North Central Plains, and the Rolling Plains. In Oklahoma the Osage Plains is divided into subregions, broad bands that stretch north-south from Kansas to Texas. The west-central subregion, lying generally west of Interstate 35, is the Red Bed Plains. West of this, in western Oklahoma, is the subregion called the Gypsum Hills (often combined with the Red Bed Plains into a larger area called the Western Red Prairies). Lying generally east of Interstate 35 is the Flint Hills/Sandstone Hills subregion. To the east of that, the Eastern Lowlands region is often included in the Osage Plains.
The topography of the Osage Plains began forming during the Cretaceous Period when an epeiric (shallow continental) sea covered the region, depositing carbonate rocks. Pulses of siliciclastic rocks were laid down due to tectonic activity to the south. More sediments washed into the region from the Rocky Mountains during the Tertiary. Soils are Pennsylvanian-age mollisols, alfisols, usfosols, and inceptisols. Tectonic activity played little role since the Cretaceous, and the region remained one of relatively flat plains to gently rolling hills. The average relief is between three hundred and five hundred feet. Oklahoma's three main river systems, the Salt Fork of the Arkansas, the Canadian, and the Red, traverse the broad region, flowing generally from west to east as the elevation of the plains gently declines in that direction.
The Osage Plains lie within the Prairie Parkland (Temperate) ecological province. Winters are cold, and summers are hot. The mean annual temperature is 60° F. This provides an average 235-day growing season. Natural vegetation varies across the Osage Plains. The overall aspect is one of tallgrass prairie that grades into savannah, woodlands, and mixed grasses. A broad band of the Cross Timbers extends as far west as Seiling, as far east as the Ozark Plateau, and from Kansas to Texas. Native grasses grow over the region's rolling hills and plains. Tallgrasses were the area's predominant vegetation until the late nineteenth century, when white settlers began clearing land for agriculture and wood. Among the tallgrasses that survived the settlement era include big bluestem (Andropogen gerardii), little bluestem (Schizachyrium scoparium), Indian grass (Sorghastrum nutans), and switchgrass (Panicum virgatum). These grasses can still be observed at the Tallgrass Prairie Preserve in Osage County, Oklahoma. Early territorial farmers introduced the Osage orange tree (also known as bois d'arc), named for the Osage people, into the Osage Plains as a living fence. The living fence was accomplished by planting many young trees in a line and pruning for thick, bushy growth. After barbed wire was introduced, the Osage orange primarily served as fence posts.
Pre-dating the first European settlers in the Osage Plains were American Indians. Tribes such as the Kaw, Omaha, Quapaw, Ponca, Kiowa, Comanche, and Osage lived in the territory. Many Osage migrated from Missouri around 1802, when the tribe split into factions. A large group followed Cashesgra, or "Big Track," relocating along the Three Forks area, where the Arkansas, Verdigris, and Grand Rivers merged, in present Oklahoma. On July 15, 1870, the U.S. government moved the tribe to present Osage County. In the twentieth century the Osage Nation acquired wealth from oil and gas extraction.
The Osage Plains lay in both Indian Territory (eastern Oklahoma) and Oklahoma Territory (western Oklahoma). After land openings and tribal land allotment took place, by the beginning of the twenty-first century towns and cities dotted the Osage Plains. Farming, ranching, and petroleum production have been the dominant economic activities. However, in some domains there are vegetation and wildlife reserves. Among the wildlife protected in these reserves are birds, including the prairie chicken, and bison. The Tallgrass Prairie Preserve in Osage County protects the remaining regional tallgrasses.
BIBLIOGRAPHY: James M. Goodman, "Physical Environments of Oklahoma," in Geography of Oklahoma, ed. John W. Morris (Oklahoma City, Okla.: Oklahoma Historical Society, 1977). Kenneth S. Johnson, "Mountains, Streams, and Lakes of Oklahoma," Oklahoma Geological Survey Informational Series No. 1 (Norman: Oklahoma Geological Survey, 1998). Kenneth S. Johnson, et al., Geology and Earth Resources of Oklahoma: An Atlas of Maps and Cross Sections (Norman: Oklahoma Geological Survey, 1972). John W. Morris, Oklahoma Geography (Oklahoma City-Chattanooga: Harlow Publishing Corporation, 1954). John W. Morris, Charles R. Goins, and Edwin C. McReynolds, Historical Atlas of Oklahoma (Norman: University of Oklahoma Press, 1986).
Melanie L. McPhail and Richard A. Marston
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