Green Pond Marsh and 50 percent to 90 percent sand and have loamy sand or sandy loam textures." The work describes hydrologic soil group C as having "moderately high runoff potential when thoroughly wet. Water transmission through the soil is somewhat restricted. Group c soils typically have between 20 percent and 40 percent clay and less than 50 percent sand and have loam, sandy clay loam, clay loam and silty clay loam textures." Green Pond Marsh is in a section of Northampton County with karst geological features. Karst geology manifests itself on topographic maps with closed, semi-closed, or linear depressions. The depressions are
Soil as a static substrate. However, soil is the result of evolution from more ancient geological materials, under the action of biotic and abiotic (not associated with life) processes. After studies of the improvement of the soil commenced, others began to study soil genesis and as a result also soil types and classifications. In 1860, in Mississippi, Eugene W. Hilgard studied the relationship among rock material, climate, and vegetation, and the type of soils that were developed. He realised that the soils were dynamic, and considered soil types classification. Unfortunately his work was not continued. At about the same time, Friedrich