Delassus soils have fragipans and are at lower elevations. Irondale soils have more than 35 percent coarse fragments in the upper argillic horizon and commonly are on steeper slopes surrounding the Knobtop soils. Loughboro soils are poorly drained and are on nearly level areas at the foot of the mountains. Moderately well drained. Runoff is medium.
Permeability is moderately slow.
Most areas remain in mixed hardwood forest because of inaccessibility. A few acres are cleared for pasture and hay. The St. Francois Mountains of Southeast Missouri. The series is of small extent. St. Francois County, Missouri, 1979.