feet, surface, level, depth, upper, Feet, width, slope, floor, running, sand, south, cubic, occur, rise, heavy, opening, vertical, soil, dry, soft, hills, parallel, located, front, openings, wet, abundant, rises, fifty, layer, rough, occasionally, areas, lime, exposure, spread, valleys, sharp, deeper, leaving, immense, surfaces, extend, uniform, closed, formed, zone, downward