It parallels the Arkansas River between the flat plains of western Oklahoma and the Arkansas Delta, dividing the Ozarks and the Ouachita Mountains with the broad valleys created by the river's floodplain, occasionally interrupted by low hills, scattered ridges, and mountains.

It generally coincides with the Arkoma Basin, an oil and gas province, that developed as sand and mud were deposited in a depression north of the rising Ouachita Mountains during the Mississippian and Pennsylvanian eras.

It is underlain by Pennsylvanian sandstone and shale; calcareous rocks such as those that dominate the Ozark Highlands are absent.

Nutrient and mineral values (including turbidity and hardness) in streams are slightly higher than in other parts of the Arkansas Valley.

The Arkansas River Floodplain ecoregion is characteristically veneered with Holocene alluvium and includes natural levees, meander scars, oxbow lakes, point bars, swales, and backswamps.

Mollisols, Entisols, Alfisols, and Inceptisols are common; the soil mosaic sharply contrasts with nearby, higher elevation ecoregions where Ultisols developed under upland oaks, hickory, and pine.

Bell Slough WMA is home to the moist-soil wetlands, bottomland hardwood forest, and prairie attractive to migratory waterfowl along the Mississippi Flyway, as well as upland hardwood and pine forest in a transition zone toward the upland mountains.

The Arkansas Valley Plains ecoregion is in the rainshadow of the Fourche Mountains and was once covered by a distinctive mosaic of prairie, savanna, and woodland.

Prior to the 19th century, frequently burned western areas had extensive prairie on droughty soils; scattered pine–oak savanna also occurred.

[3] Small remnants of this ecoregion are preserved in Arkansas, including Cherokee Prairie Natural Area and H.E.

It acts as a transition between the drier Cross Timbers to the west and moister parts of the Arkansas Valley to the east.

In general, wooded hills are more widespread than in the nearby Arkansas Valley Plains and Osage Cuestas.

Fish and macroinvertebrate species richness is greater than in the Cross Timbers, but less than in the rest of the Arkansas Valley.