The Moonbend series consists of very deep, somewhat poorly drained soils on floodplains. These soils formed in alluvium weathered from mixed rock sources. Slope ranges from 0 to 2 percent. The mean annual precipitation is 14 to 16 inches, and the mean annual temperature is 60 to 62 degrees F.

Taxonomic class: Fine-silty, mixed, superactive, thermic Pachic Haploxerolls

Moonbend silt loam, 0 to 2 percent slopes, cropland. When described on October 24, 1988, the soil was moist throughout.

Ap—0 to 8 inches; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; weak medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; few very fine roots; common fine tubular pores; neutral (pH 7.1); clear smooth boundary.

Bw1—8 to 19 inches; grayish brown (10YR 5/2) silty clay loam, dark brown (10YR 3/3) moist; moderate medium prismatic parting to subangular blocky structure; hard, friable, slightly sticky and slightly plastic; few very fine roots; common fine, medium and coarse and few very fine tubular pores; few thin silt coatings line pores; neutral (pH 7.0); clear smooth boundary.

Bw2—19 to 34 inches; grayish brown (10YR 5/2) silty clay loam, dark brown (10YR 3/3) moist; weak medium prismatic parting to moderate medium subangular blocky structure; very hard, friable, slightly sticky and slightly plastic; few very fine roots; many very fine and common fine and medium tubular pores; common thin silt coatings line pores; neutral (pH 7.2); clear smooth boundary.

Bw3—34 to 42 inches; grayish brown (10YR 5/2) loam, dark brown (10YR 3/3) moist; weak medium prismatic parting to moderate medium subangular blocky structure; very hard, friable, slightly sticky and slightly plastic; few very fine roots; many fine medium and common very fine tubular pores; neutral (pH 7.0); clear smooth boundary.

BC—42 to 52 inches; pale brown (10YR 6/3) silt loam, dark brown (10YR 3/3) moist; moderate medium subangular blocky structure; very hard, friable, slightly sticky and slightly plastic; few very fine roots; common fine and medium tubular pores; neutral (pH 7.0); clear smooth boundary.

C—52 to 64 inches; pale brown (10YR 6/3) silt loam, dark brown (10YR 3/3) moist; massive; hard, friable, slightly sticky and slightly plastic; few very fine roots; many very fine tubular pores; slightly effervescent; moderately alkaline (pH 7.9); clear smooth boundary.

Ab—64 to 76 inches; grayish brown (10YR 5/2) silt loam, very dark grayish brown (10YR 3/2) moist; moderate medium subangular blocky structure; hard, friable, slightly sticky and slightly plastic; common very fine tubular pores; slightly effervescent; moderately alkaline (pH 7.9); clear smooth boundary.

C’—76 to 86 inches; light yellowish brown (10YR 6/4) loam, brown (7.5YR 4/4) moist; massive; hard, friable, nonsticky and nonplastic; many very fine tubular pores; slightly effervescent; slightly alkaline (pH 7.7).

Type location: Colusa County, California; located about 1 1/2 miles southeast of Colusa, California in an unsectionalized area, 1900 feet east and 450 feet north of the southwest corner of section 33, T. 16 N., R. 1 W., MDB&M; 39 degrees, 11 minutes, 15 seconds north latitude and 121 degrees, 58 minutes, 45 seconds west longitude; USGS Meridian, California topographic quadrangle.

The solum ranges from 40 to 80 inches thick. Mean annual soil temperature is 63 to 65 degrees F and the soil temperature is not below 47 degrees F at any time. The soil moisture control section, 6 and 17 inches, is dry in all parts from May 15 to October 31 and moist in some or all parts from November 15 to May 1. Weighted average clay content of the 10 to 40 inch textural control section is 27 to 35 percent. Fine sand or coarser sand ranges from 2 to 6 percent. The mollic epipedon is 25 to 42 inches thick.

The Ap horizon is 10YR 5/2. Moist color is 10YR 3/3, 3/2. Texture is silt loam. Reaction is neutral.

The Bw horizon is 10YR 6/3, 6/2, 5/3, 5/2. Moist color is 10YR 4/3, 3/3, 3/2. Texture is loam, silt loam, silty clay loam, or clay loam, with 18 to 35 percent clay. Reaction is neutral to moderately alkaline.

The C horizon is 10YR 6/4, 6/3, 5/3. Moist color is 10YR 4/4, 4/3, 3/3; 7.5YR 4/4. Texture is loam or silt loam. Reaction is slightly alkaline to moderately alkaline.