Six Natural Divisions

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Entry Category: Six Natural Divisions

Arkansas Valley

aka: Arkansas River Valley
The Arkansas Valley, one of the six natural divisions of Arkansas, lies between the Ozark Mountains to the north and the Ouachita Mountains to the south. It generally parallels the Arkansas River (and Interstate 40) for most of its length. Its largest city is Fort Smith (Sebastian County), but many other cities are located there, including Van Buren (Crawford County), Alma (Crawford County), Ozark (Franklin County), Booneville (Logan County), Clarksville (Johnson County), Russellville (Pope County), Dardanelle (Yell County), and Morrilton (Conway County). Conway (Faulkner County), Heber Springs (Cleburne County), and Searcy (White County) are located near its boundary. The Arkansas Valley is up to forty miles wide and includes geological features typical of both the Ozarks and the Ouachitas, including …

Crowley’s Ridge

Crowley’s Ridge is a small yet distinctive natural region. It ranges in width from one to twelve miles and extends from southern Missouri across eastern Arkansas to Helena-West Helena (Phillips County). It is made up of a continuous series of rolling hills except for a slight break at Marianna (Lee County); this break or gap was created by the L’Anguille River as it flowed across the ridge. The ridge received its name from Benjamin Crowley, the first white settler to reach the area near present-day Paragould (Greene County), sometime around 1820. Also of note is that the Civil War Skirmish at Chalk Bluff was fought on Crowley’s Ridge on May 1–2, 1863. The Chalk Bluff Natural Area in Clay County …

Mississippi Alluvial Plain

aka: Mississippi Delta
aka: Arkansas Delta
aka: Delta
aka: Mississippi River Delta
aka: Mississippi River Valley
The Mississippi Alluvial Plain (a.k.a. Delta) is a distinctive natural region, in part because of its flat surface configuration and the dominance of physical features created by the flow of large streams. This unique physiography occupies much of eastern Arkansas including all or parts of twenty-seven counties. The Alluvial Plain, flatter than any other region in the state, has elevations ranging from 100 to 300 feet above sea level. In Arkansas, the Alluvial Plain extends some 250 miles in length from north to south and varies in width from east to west from only twelve miles in Desha County to as much as ninety-one miles measured from Little Rock (Pulaski County) to the Mississippi River. The work of large rivers …

Ouachita Mountains

aka: Ouachitas
The Ouachita Mountains, one of the six natural divisions of Arkansas, are generally characterized as folded ridges and valleys composed of Paleozoic rocks. They are unusual in North America in that the ridges are generally aligned east to west, unlike the Rocky Mountains or Appalachian Mountains, where the ridges usually run north to south. The most striking result of this orientation is that there is an extensive south-facing slope on each ridge that is exposed to the heat and light of the sun, as well as a north-facing slope that is protected from direct solar radiation and is consequently cooler and moister. The dry south-facing slopes are often covered with pine forests or woodlands, or even drier oak woodlands, while …

Ozark Mountains

aka: Ozarks
The Ozark Mountains (a.k.a. the Ozark Plateau or Plateaus), representing one of the six natural divisions of Arkansas, are generally characterized as uplifted level plateaus composed of Paleozoic rocks. Streams have cut valleys into these plateaus, and, in some cases, the plateau surface is only visible as the flat tops of the mountains at similar elevations. The three distinct plateaus differ in topography, geology, vegetation, as well as inhabitants’ land use, history, and culture. Boston Plateau At up to 2,600 feet, the Boston Plateau, usually referred to as the Boston Mountains because of its ruggedness, is the highest of the Ozark Mountains. It extends as a belt across the southernmost Ozarks, generally parallel to and to the north of Interstate …

West Gulf Coastal Plain

aka: Gulf Coastal Plain
aka: Coastal Plain
The Gulf Coastal Plain is an area of relatively gently sloping terrain extending across the southern portion of the United States from Texas to Georgia. It was covered by the waters of the Gulf of Mexico until about 50 million years ago. The land rose during periods of tectonic uplift, and water in the Gulf of Mexico retreated to near its present position. Because it was covered by the waters of the Gulf of Mexico for much of its history, the geologic terrain of the Coastal Plain is flat to rolling. Its bedrock is deeply covered with sediment, and the surface has extensive deposits of sand and gravel. The western portion of the Gulf Coastal Plain—the West Gulf Coastal Plain—extends …