LOCATION SPLAWN CAEstablished Series
TAXONOMIC CLASS: Clayey-skeletal, smectitic, mesic Ultic Argixerolls
TYPICAL PEDON: Splawn very cobbly loam on a northwest facing slope of 2 percent under a cover of pine, juniper and oak at elevation of 3400 feet. (Colors are for dry soil unless otherwise stated. When described on September 20, 1980 the soil was moist to 11 inches)
Oi--1 to 0 inches; recent and decomposing oak and pine litter.
A1--0 to 3 inches; brown (10YR 5/3) very cobbly loam, dark brown (10YR 3/3) moist; strong fine granular and moderate fine subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine roots; common fine tubular pores; 30 percent cobbles, 20 percent gravel; neutral (pH 6.8); clear smooth boundary.
A2--3 to 10 inches; dark brown (10YR 4/3) very gravelly loam, dark brown (10YR 3/3) moist; moderate fine subangular blocky structure; hard, friable, slightly sticky and slightly plastic; common very fine and fine roots; common fine tubular pores; 45 percent gravel, 10 percent cobbles; neutral (pH 6.8); clear wavy boundary. (Combined thickness of the A horizon is 8 to 16 inches)
Bt1-10 to 17 inches; dark brown (7.5YR 4/4) very gravelly clay loam, dark brown (10YR 3/3) moist; strong fine subangular blocky structure; very hard, friable, sticky and plastic; few very fine, fine and medium roots; common fine tubular pores; common moderately thick clay films in pores and many thin clay films on peds; 50 percent gravel, 5 percent cobbles; neutral (pH 6.8); clear irregular boundary. (6 to 12 inches thick)
Bt2--17 to 24 inches; strong brown (7.5YR 4/6) extremely gravelly clay loam, dark brown (7.5YR 3/4) moist; strong fine angular blocky structure; very hard, firm, sticky and plastic; few very fine, fine and common medium roots; few fine tubular pores; many moderately thick clay films in pores and on peds; 60 percent gravel, 10 percent cobbles; neutral (pH 6.8); abrupt wavy boundary. (6 to 12 inches thick)
R--24 inches; hard basalt with few fractures.
TYPE LOCATION: Shasta County, California, about 1.3 miles northeast of Cassel on Cassel-Fall River Rd., north 1.2 miles on dirt road to Conrad Ranch, 900 feet southeast on dirt road 500 feet east of road; 200 feet east and 1.900 feet south of the northwest corner, sec. 34, T. 36 N., R. 4 E. Burney NE (Cassel) quadrangle (7.5 minute series).
RANGE IN CHARACTERISTICS: Depth to bedrock is 20 to 40 inches. The mean annual soil temperature is 47 to 52 degrees F. The soil temperature exceeds 41 degrees F.from early March to late December (305 days) and exceeds 47 degrees F. from early April to early December. The moisture control section (10 inches to the lithic contact) is dry in all parts from mid June to late October (130 to 140 days). Rock fragments, mostly cobbles on the soil surface, range from 35 to 50 percent. Base saturation by sum of cations ranges from 60 to 75 percent.
The A horizon color is 10YR 5/3, 5/2, 4/3, or 4/2. Moist color is 10YR 3/3, 3/2, 2/2; or 7.5YR 3/2. Clay content ranges from 18 to 27 percent. Rock fragments range from 35 to 60 percent by volume. Gravel ranges from 20 to 50 percent. Cobbles range from 10 to 30 percent.
The Bt horizon color is 7.5YR 4/4, 5/4; 5YR 4/4, 4/3, or 3/3 in the upper part and 7.5YR 4/6, 4/4 or 5/4 in the lower part. Moist color is 10YR 3/3; 7.5YR 3/2; 5YR 3/3, or 3/4 in the upper part and 5YR 3/4 or 7.5YR 3/4 in the lower part. Texture ranges from very gravelly clay loam, extremely gravelly clay loam, or extremely gravelly clay. Clay content ranges from 35 to 50 percent. Rock fragments range from 40 to 80 percent by volume. Gravel ranges from 35 to 75 percent. Cobbles range from 5 to 40 percent.
COMPETING SERIES: There are no other series in this family.
GEOGRAPHIC SETTING: Splawn soils are on hills and lava plateaus. Slopes are 2 to 50 percent. These soils formed in material weathered from basalt. Elevations are 3200 to 5000 feet. The climate is semiarid with warm dry summers and cold moist winters. Mean annual precipitation is 12 to 20 inches. Snowfall is 12 to 24 inches. Mean annual temperature is 45 to 50 degrees F. The frost free season is 80 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Gassaway (T), Jellico (T), Jellycamp, and Ollierivas (T) soils. Gassaway soils are on lava flows, are less than 20 inches deep and loamy. Jellycamp soils are on intermounds on plateaus, are less than 20 inches deep to a duripan, and clayey. Jellico soils are loamy-skeletal. Ollierivas soils are on mounds on plateaus, are fine and underlain by a duripan.
DRAINAGE AND PERMEABILITY: Well drained; slow to rapid runoff; slow permeability.
USE AND VEGETATION: Used for wildlife habitat and grazing. The natural vegetation is mainly digger and Jeffrey pine, western juniper, Oregon white oak, Idaho fescue, bottlebrush squirreltail and Thurber needlegrass.
DISTRIBUTION AND EXTENT: Northeastern California.The soils are of small extent. MLRA is 22.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Shasta County, Intermountain Soil Survey Area, California 1994. Source of name is from a mountain.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - 0 to 17 inches (A1, A2, Bt1).
Argillic horizon - 17 to 24 inches (Bt1, Bt2).
Lithic Contact - the boundary at about 24 inches.