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
Dilatancy (granular material) so coarse and thus may be described as dense to very dense. Vertical excavations below the water table in these soil types exhibit short term stability, similar to many dense sandy soil deposits, in part due to matric suction. However, as shearing of the soil occurs in the active wedge due to gravity forces, strength is lost and the rate of failure accelerates. This can be exacerbated by hydrostatic forces developing at the location(s) where water (drains to and) collects in tension cracks in or near the back of the active wedge. Generally retrogressive spalling manifests, often accompanied by piping