PONTOTOC RIDGE is an elevated area of land lying between four and six hundred feet above sea level. It forms the divide between the Tombigbee and the Mississippi drainage systems in the northern part of the state. From Houston in Chickasaw County, the ridge extends almost due north to the Tennessee line. Accentuated by the level FLATWOODS on the west and the PRAIRIE LANDS on the east it forms a prominent topographic feature of that part of the state.
The rocks composing the ridge are principally the marls and sands of the RIPLEY formation, which is now thought by some to be of the same age as the upper part of the Selma chalk, farther south. The Ripley is capped, for the most part, with sands and clays of the LAFAYETTE formation, of probably the Pliocene age.
The soils of Pontotoc Ridge are derived largely from the Lafayette red sands and clays. Small areas of residual soils derived from the Ripley are also present, and it is possible that the Lafayette itself is at least partly composed of materials from the Ripley. However that may be, these soils are in other parts of the state.
The soils of this area are principally of two types - a REDDISH CLAY and SANDY LOAM. The former is the most abundant type of the region, and ranges in depth from three to nine inches. The sub-soil is either a plastic red clay or mottled sandy clay. In limited areas both soil and subsoil will contain a high percent of sand. The read clay soil is composed of about twenty-nine percent of sand, fifty-eight percent of silt, and thirteen percent of clay. On an average the subsoil contains less silt and more clay than the soil. The sandy loam soil is deeper as a rule than the clay soil. It contains about sixty four percent of sand, twenty four percent of silt, and twelve percent of clay. The mechanical condition of the sub-soil is about the same as that of the clay type, but consists of less silt, more very fine sand, and more than three times as much clay as the soil. Drainage in the loam type is sometimes excessive, and liming and the incorporation of more organic matter is desirable in order that it may be rendered more retentive to moisture.
Immediately west of the northeast prairie and the Pontotoc Ridge, lies a narrow belt of level land called the Flatwoods. The width of the belt varies from six to twelve miles; in length it extends from Kemper County to the Tennessee Line. The lands, as a rule, are flat, the elevation varying from two hundred to three hundred feet above sea level. The natural drainage of the area, as would be expected from the level nature of the land, is generally poor, the streams pursuing meandering courses. The entire region is largely uncultivated and in forests. The area, as a whole, has been looked upon as unsuited for agricultural purposes, but this has proved a hasty judgment as it has been demonstrated that some of the soils in the area when properly cultivated produce excellent crops.
The principal soil of the area is a RESIDUAL, derived from the weathering of heavy clay. This clay belongs to the Flatwoods or Porter's Creek division of the Eocene epoch. The clay from which the soil is derived is a fine-grained clay, containing a high percent of finely divided silica. This clay contains a relatively small amount of lime, and the soils derived from it are consequently deficient in lime. The soils formed along the flood plains of the streams in the Flatwoods are usually loams, composed, in part, of particles from that area, and in part from bordering areas. The residual soil, formed from the Flatwoods Clay, has a texture varying from a clay to a silt loam. The sub-soil is usually a tough, plastic clay. In color, the soil varies from grey to dark brown. On account of the undrained condition of much of this type the proper moisture condition is often difficult to obtain during the plowing season, and the fields are frequently cloddy. As the clods do not dissolve readily, they may persist during the growing season and interfere with the cultivation and the growing of the crops. The depth of the soil is from four to five inches and is composed of about fifteen percent of clay, seventy five percent of silt and ten percent of fine sand. The sub-soil has about the same amount of sand.
The alluvial soils of the Flatwoods are CLAYS and LOAMS found along the flood plains of streams. These soils vary much in their physical and chemical characteristics, which is due to the variable condition of their origin. Some of the soils are composed of soil particles obtained, in part, from the Pontotoc Ridge; other of particles from the northeast prairie, and still others of particles from the shortleaf pine soil area. The color of the soil is usually a brownish gray, with a grayish clay subsoil containing iron concretions. In many places the heavier soils contain about forty five percent of clay, fifty five percent of silt, and ten percent of fine sand. The sub-soil contains about ten percent more clay and proportionately smaller amounts of sand.