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<br />Land Resource <br /> <br />Soil Survey _ Variations in climate, biological forces, relief, parent <br />materials and age of land surfaces within the study area have resulted in <br />a complex pattern of soils and miscellaneous land areas. Soil orders <br />represented include Aridisols, Entisols and Inceptiso1s which are considered <br />to be potential sources of salts and sediments to the resources. <br /> <br />The following descriptions indicate the general character of the soil <br />associations in the study area. The Soils Map (Figure 7) shows their <br />distribution. <br /> <br />G1enda1e-Gila-Toquop Association: Deep, well drained and excessively <br />drained, nearly level to moderately sloping soils; on flood plains, low <br />stream terraces and alluvial fans. Surface soil is loam or fine sand or <br />fine sandy loam. <br /> <br />Toquop-Calico-Overton Association: Deep, excessively drained, somewhat <br />poorly drained, and very poorly drained, nearly level to moderately sloping <br />soils; on flood plains, broad terraces and alluvial fans. Surface soil is <br />fine sand or fine sandy loam or silty clay. <br /> <br />Toquop-Virgin River-Land Association: Deep, excessively drained, some- <br />what poorly drained and very poorly drained, nearly level to moderately <br />sloping soils; on flood plains, broad terraces and alluvial fans. Surface <br />soil is fine sand, or fine sandy loam ur silty clay. This soil unit is <br />considered to have a high salt content. <br /> <br />Mormon Mesa-Arada-Flattop Association: Shallow to deep, well drained <br />and somewhat excessively drained, nearly level to moderately sloping soils; <br />on Mormon Mesa and on terraces and alluvial fans. In the study area the <br />surface soil is fine sandy loam or fine sand. <br /> <br />Bard-Colorock-Tonopah Association: Moderately deep and deep, well <br />drained and escessively drained, ne&rly level to strongly sloping soils; on <br />broad alluvial fans and c1ld terraces. Surface soil 1s gravelly sandy loam <br />or gravelly fine sandy loam. <br /> <br />Badland-Bard-Tonopah Association: Badland, and moderately deep and <br />deep, well drained and excessively drained, nearly level to strongly sloping <br />soils; on old terraces and alluvial fans. Badland consists of severely eroded <br />and gullied areas. It is higf,ly stratified deposits of silt and clay that <br />contain a largp. amount of gypsum and calcium carbonate. The other units <br />have surface soil of gravelly sand and fine sandy loam. <br /> <br />Rockland-St. Thomas-Moapa Association: Shallow and moderately deep, <br />well drained, moderately steep to very steep soils; on mountains and colluvial <br />foothills. The St. Thom~s surface soil is a cobbly loam, while the Moapa <br />surface soil is fine sand. <br /> <br />Figure 7 is a soils map for the Subevaluation Unit. <br /> <br />r. (' 0 r; 9 9 <br />\..;.......u <br /> <br />19 <br />