Title: Geography of Oklahoma
Content:   The  Geography of Oklahoma encompasses terrain and ecosystems ranging from arid plains to subtropical forests and mountains. Oklahoma contains 10 distinct ecological regions, more per square mile than in any other state by a wide margin. It is situated in the Great Plains and U.S. Interior Highlands region near the geographical center of the 48 contiguous states. Usually considered part of the South Central United States, Oklahoma is bounded on the east by Arkansas and Missouri, on the north by Kansas, on the northwest by Colorado, on the far west by New Mexico, and on the south and near-west by Texas. The state has four primary mountain ranges: the Arbuckle Mountains, the Wichita Mountains, the Ozark Mountains and the Ouachita Mountains. Part of the U.S. Interior Highlands region, the Ozarks and Ouachitas form the 
Title: Geography of Arkansas
Content:  Arkansas's regions are defined using many different criteria. Distinct natural regions of Arkansas include The Ozarks, Ouachita Mountains, Arkansas River Valley, Gulf Coastal Plain, Crowley's Ridge, the Arkansas Delta, Arkansas Timberlands, and Central Arkansas. Arkansans usually identify as being from one of five regions: northwest, southwest, northeast, southeast, or central Arkansas. These directional regions are not specifically defined by county.
Title: Oklahoma
Content:  marked by extreme differences in geographical diversity: Eastern Oklahoma touches eight ecological regions and its western half contains three. Although having fewer ecological regions Western Oklahoma contains many rare, relic species. Oklahoma has four primary mountain ranges: the Ouachita Mountains, the Arbuckle Mountains, the Wichita Mountains, and the Ozark Mountains. Contained within the U.S. Interior Highlands region, the Ozark and Ouachita Mountains are the only major mountainous region between the Rocky Mountains and the Appalachians. A portion of the Flint Hills stretches into north-central Oklahoma, and near the state's eastern border, The Oklahoma Tourism & Recreation Department regards Cavanal Hill as the world's tallest hill; at 1999 ft, it fails their definition of a mountain by one foot. The semi-arid high plains in the state's northwestern corner harbor few 
Title: Region
Content:  In geography, regions are areas that are broadly divided by physical characteristics (physical geography), human impact characteristics (human geography), and the interaction of humanity and the environment (environmental geography). Geographic regions and sub-regions are mostly described by their imprecisely defined, and sometimes transitory boundaries, except in human geography, where jurisdiction areas such as national borders are defined in law. Apart from the global continental regions, there are also hydrospheric and atmospheric regions that cover the oceans, and discrete climates above the land and water masses of the planet. The land and water global regions are divided into subregions geographically bounded by large geological features that influence large-scale ecologies, such as plains and features. As a way of describing spatial areas, the concept of regions is important and widely used among the many branches of geography, each of which can 
Title: Oklahoma
Content:  Oklahoma is between the Great Plains and the Ozark Plateau in the Gulf of Mexico watershed, generally sloping from the high plains of its western boundary to the low wetlands of its southeastern boundary. Its highest and lowest points follow this trend, with its highest peak, Black Mesa, at 4973 ft above sea level, situated near its far northwest corner in the Oklahoma Panhandle. The state's lowest point is on the Little River near its far southeastern boundary near the town of Idabel, which dips to 289 ft above sea level. Among the most geographically diverse states, Oklahoma is one of four to harbor more than 10 distinct ecological regions, with 11 in its borders—more per square mile than in any other state. Its western and eastern halves, however, 
Title: Geography of Oklahoma
Content:  major highland region between the Rocky Mountains and the Appalachians. A portion of the Flint Hills stretches into north-central Oklahoma, and in the state's southeastern corner, Cavanal Hill is officially regarded as the world's tallest hill; at 1,999 feet (609 m), it fails the definition of a mountain by one foot. More than 500 named creeks and rivers make up Oklahoma's waterways, and with 200 lakes created by dams, it holds the highest number of reservoirs in the nation. Oklahoma covers an area of 69,898 sqmi, with 68,667 sqmi of land and 1,231 sqmi of water, making it the 20th-largest state in the United States. Generally, it is divided into seven geographical regions: Green Country, or Northeast Oklahoma, Southeastern Oklahoma, Central Oklahoma, South Central Oklahoma, Southwest Oklahoma, Northwest Oklahoma, and the Oklahoma Panhandle.
Title: History of Oklahoma
Content:  Topographically, Oklahoma is situated between the Great Plains and the Ozark Plateau in the Gulf of Mexico watershed. The western part of the state is subjected to extended periods of drought and high winds which generates Dust storms. The eastern part of the state is humid subtropical climate zone. The Dry line, an imaginary line that separates moist air from an eastern body of water and more arid air from the west, usually bisects the state and is arguably an important factor in precontact settlement.
Title: South Central Oklahoma
Content:   South Central Oklahoma is an amorphous region in the state of Oklahoma, perhaps encompassing 10 counties. It is centered on the Arbuckle Mountains, an ancient, eroded range traversing some 70 mi across the region, and surrounded by rivers and lakes, notably Lake Texoma, Lake Murray and Lake of the Arbuckles. For tourism purposes, the Oklahoma Department of Tourism has more narrowly defined South Central Oklahoma, which they refer to as Chickasaw Country, as being a seven-county region including Pontotoc, Johnston, Marshall, Garvin, Murray, Carter, and Love counties. A ten-county definition might also include Coal, Atoka, and Bryan counties, although the Department of Tourism includes 
Title: Osage Plains
Content:  The Osage Plains are a physiographic section of the larger Central Lowland province, which in turn is part of the larger Interior Plains physiographic division. The area is sometimes called the Lower Plains, North Central Plains,or Rolling Plains. The Osage Plains, covering west-central Missouri, the southeastern third of Kansas, most of central Oklahoma, and extending into north-central Texas, is the southernmost of three tallgrass prairie physiographic areas. It grades into savanna and woodland to the east and south, and into shorter, mixed-grass prairie to the west. The Osage Plains consist of three subregions. The Osage Plains proper occupy the northeast segment. Although sharply demarcated from the Ozark uplift, the 
Title: List of regions of the United States
Content: Region I: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, Vermont ; Region II: New Jersey, New York, Puerto Rico, US Virgin Islands ; Region III: Delaware, District of Columbia, Maryland, Pennsylvania, Virginia, West Virginia ; Region IV: Alabama, Florida, Georgia, Kentucky, Mississippi, North Carolina, South Carolina, Tennessee ; Region V: Illinois, Indiana, Michigan, Minnesota, Ohio, Wisconsin ; Region VI: Arkansas, Louisiana, New Mexico, Oklahoma, Texas ; Region VII: Iowa, Kansas, Missouri, Nebraska ; Region VIII: Colorado, Montana, North Dakota, South Dakota, Utah, Wyoming ; Region IX: Arizona, California, Hawaii, Nevada, American Samoa, Guam, Northern Mariana Islands ; Region X: Alaska, Idaho, Oregon, Washington  The ten standard federal regions were established by OMB (Office of Management and Budget) Circular A-105, "Standard Federal Regions", in April 1974, and went into use for all executive agencies. In recent years, some agencies have tailored their field structures to meet program needs and facilitate interaction with local, state, and regional counterparts. However, the OMB must still approve any departures. Note: OMB Circular A-105 was rescinded on June 8, 1995.

Question: oklahoma's 10 geographic regions are defined by surface features called?
Answer: ecological regions.