Occurrence and Characteristics of Fragipan-like Formations in Selected Coastal Plain Soils

Particle size distribution, bulk density, silica, sesquioxides and degree of cementation in the Carnegie, Cowarts and Irvington series having compact horizons, indicate that these horizons or formations have high bulk density, are hard to extremely hard when dry, firm to very firm when moist and/are brittle in moist and dry states. Scanning electron micrographs depict close packing and highly oriented soil particles. Connecting strands of fine material may lend rigidity and cause brittle consistence to the compacted horizon. Clay, Si, Fe, Al, CaCO₃, and carbon do not seem to be related to cementation. The compacted formations readily slake in water. The relatively coarse texture, low Si, Fe and Al content, absence of free CaCO₃, very low carbon content, high bulk density, close packing of particles and slaking behaviour indicate that these types of formation which commonly occur in many coastal plain soils are fragipans.