These directionally named regions are broad and not defined along county lines.Arkansas has seven distinct natural regions: the Ozark Mountains, Ouachita Mountains, Arkansas River Valley, Gulf Coastal Plain, Crowley's Ridge, and the Arkansas Delta, with Central Arkansas sometimes included as a blend of multiple regions.Farther away from the river, in the southeast portion of the state, the Grand Prairie consists of a more undulating landscape. The Delta region is bisected by a geological formation known as Crowley's Ridge.A narrow band of rolling hills, Crowley's Ridge rises from 250 to 500 feet (76 to 152 m) above the surrounding alluvial plain and underlies many of the major towns of eastern Arkansas.
The word "Arkansas" itself is a French pronunciation ("Arcansas") of a Quapaw (a related "Kaw" tribe) word, akakaze, meaning "land of downriver people" or the Sioux word akakaze meaning "people of the south wind".
Northwest Arkansas is part of the Ozark Plateau including the Ozark Mountains, to the south are the Ouachita Mountains, and these regions are divided by the Arkansas River; the southern and eastern parts of Arkansas are called the Lowlands.
The Arkansas is fed by the Mulberry River and the Fourche La Fave River in the Arkansas River Valley, which is also home to Lake Dardanelle.
The Red River briefly serves as the state's boundary with Texas.
Arkansas is home to many caves, such as Blanchard Springs Caverns.