LOCATION CLOUGH CATentative Series
TAXONOMIC CLASS: Clayey-skeletal, kaolinitic, thermic Abruptic Durixeralfs
TYPICAL PEDON: Clough gravelly loam, dry pasture. (Colors are for dry soil unless otherwise noted).
A11--0 to 6 inches; brown (10YR 5/3) gravelly loam, dark brown (7.5YR 3/4) moist; massive; slightly hard, friable, slightly sticky, slightly plastic; many very fine roots; common very fine interstitial pores; medium acid (pH 5.8); gradual smooth boundary. (4 to 8 inches thick)
A12--6 to 14 inches; brown (7.5YR 5/4) gravelly loam, brown (7.5YR 4/3) moist; massive; slightly hard, friable, slightly sticky, slightly plastic; common very fine roots; many very fine interstitial and tubular pores; medium acid (pH 5.8); clear smooth boundary. (3 to 10 inches thick)
A3--14 to 18 inches; brown (7.5YR 5/4) gravelly heavy loam, brown (7.5YR 4/4) moist; massive; slightly hard, friable, slightly sticky, slightly plastic; common very fine roots; common very fine interstitial and tubular pores; few thin clay films in pores; medium acid (pH 5.8); abrupt smooth boundary. (0 to 6 inches thick)
B2t--18 to 24 inches; light yellowish brown (10YR 6/4) very gravelly clay yellowish brown (10YR 5/4) moist; common medium prominent white mottles; massive; very hard, firm, sticky, very plastic; very few very fine roots; few very fine tubular pores (pH 4.5); continuous thick clay films as bridges; very strongly acid; clear smooth boundary. (5 to 8 inches thick)
B3t--24 to 29 inches; light yellowish brown (10YR 6/4) very gravelly clay loam, yellowish brown (10YR 5/4) moist; with common fine distinct reddish yellow mottles; massive; hard, firm, sticky, plastic; few very fine tubular pores; continuous moderately thick clay films as bridges; very strongly acid (pH 4.5); abrupt smooth boundary. (3 to 6 inches thick)
Cm--29 to 34 inches; mixed light gray and light yellowish brown (10YR 7/1, 6/4) very gravelly clay loam, yellowish brown (10YR 5/4) moist; massive; extremely hard, extremely firm, brittle, sticky, plastic; few moderately thick clay films as bridges; strongly cemented with opal; very strongly acid (pH 5.0).
TYPE LOCATION: Shasta County, California; 1,300 feet W of SE corner sec. 13, T. 32 N., R. 4 W., 1 3/4 miles SW of Bellavista.
RANGE IN CHARACTERISTICS: The soils become dry in the moisture control section about June 15 and remain dry until about September 15.
The Clough soils have brown, medium acid, gravelly loam A horizons that rest abruptly on very strongly acid very gravelly clay B2t horizons. The C horizons are very strongly acid strongly cemented duripans. Structure is very weak or the soils are massive.
The A horizons range in color from brown to reddish yellow (10YR, 7.5YR). Texture ranges from gravelly fine sandy loam to loam. Reaction ranges from strongly acid to medium acid. The structure usually is weak granular but in some pedons the soils are massive. They are 10 to 14 inches thick.
The B2t horizons range in color from light yellowish brown (10YR) to reddish yellow (7.5YR); in texture from gravelly or cobbly clay to gravelly clay loam. Structure usually is weak subangular blocky but in some pedons the soils are massive. Reaction is very strongly to strongly acid.
The C horizons are very strongly acid, very gravelly clay loams or clays that are strongly cemented or indurated.
COMPETING SERIES: The Clough soils are similar to the Red Bluff, Redding, Igo and Tuscan soils. The Red Bluff soils lack abrupt A-B boundaries and duripans, and have hues of 2.5YR or 10R (dry) in the B2t horizons. The Redding soils are redder (5YR and 2.5YR hues) and lack very gravelly B2t horizons. The Igo soils lack argillic horizons. The Tuscan soils are medium to slightly acid and lack very gravelly B2t horizons.
GEOGRAPHIC SETTING: Clough soils occur on gently undulating old terraces at elevations of about 200 to 1,000 feet. The sediments are gravelly alluvium that is high in quartz and cherts derived mostly from conglomerates and other sedimentary rocks. The climate is subhumid with mean annual rainfall of 30 to 40 inches, with warm dry summers and cool moist winters. Mean annual temperature is about 60 degrees F, average January temperature about 47 degrees F, and average July temperature about 75 degrees F. The frost-free season is 200 to 250 days.
GEOGRAPHICALLY ASSOCIATED SOILS: Clough soils occur in the same general area as the Manzanita, Newtown, Positas and Red Bluff soils which lack duripans and the yellowish red Redding soils.
DRAINAGE AND PERMEABILITY: Moderately well drained to somewhat poorly drained, very slowly permeable, medium runoff.
USE AND VEGETATION: Range or pasture with a few areas in grapes. Native vegetation is oaks, manzanita, poison oak, annual grasses and forbs.
DISTRIBUTION AND EXTENT: Upper Sacramento Valley and in the warm interior valleys of Sonoma County. Clough soils are inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES PROPOSED: Shasta County, California, 1965.
REMARKS: The Clough series was formerly classified in the Noncalcic Brown group.
Last revised by the state on 11/69.