Rarely, pimple mounds that occur on these hillslopes are elongated in an upslope-downslope direction.
Unlike the Mima mounds of Oregon and Washington, pimple mounds are not limited to the relatively flat and poorly drained surfaces, i . e . late Pleistocene coastal and fluvial terraces.
Pimple mounds range in diameter from 6 m to more than 45 m; in height 30 cm to greater than 1.2 m; and in density from several to greater than 425 mounds per hectare.
Third, they are found in an area containing parts of East Texas, western Louisiana, southeast Oklahoma, and southern Missouri where they are commonly known as either " pimple mounds " or " prairie mounds ".
Within Louisiana, Missouri, Oklahoma, and Texas, pimple mounds, also called locally " prairie mounds " and " natural mounds ", consist of low, flattened, circular to oval, domelike, mounds composed of loose, sandy loam or loamy sand.