LOCATION BARNABE CAEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, active, isomesic Lithic Haplustolls
TYPICAL PEDON: Barnabe very gravelly loam, on a N facing convex slope 22 percent slopes under coyotebrush, lupine, annual grasses and forbs at 720 feet elevation. (Colors are for dry soil unless otherwise stated. When described (8/9/76) the soil was dry throughout.)
A11--0 to 2 inches; grayish brown (10YR 5/2) very gravelly loam, very dark grayish brown (10YR 3/2) moist; moderate fine and medium subangular blocky structure parting to weak fine granular; hard, firm, slightly sticky and slightly plastic; many very fine and fine, few medium roots; common very fine and fine, few medium interstitial and tubular pores; 45 percent pebbles; moderately acid (pH 6.0); clear smooth boundary. (1 to 2 inches thick)
A12--2 to 8 inches; dark grayish brown (10YR 4/2) very gravelly loam, very dark gray (10YR 3/1) moist; strong fine and medium subangular blocky structure; hard, firm, slightly sticky and slightly plastic; many very fine and fine, few medium roots; many very fine and fine interstitial and tubular pores; 45 percent pebbles; slightly acid (pH 6.3); clear smooth boundary. (4 to 8 inches thick)
B2t--8 to 16 inches; very dark grayish brown (10YR 3/2) very gravelly heavy loam, black (10YR 2/1) moist; strong fine and medium subangular blocky structure; hard, friable, sticky and plastic; common very fine and fine roots; many very fine and fine interstitial and tubular pores; few thin clay films on faces of peds and in interstitial pores; 35 percent pebbles; slightly acid (pH 6.3); abrupt irregular boundary. (5 to 10 inches thick)
R--16 inches; fractured sandstone and shale. Does not slake in water.
TYPE LOCATION: Marin County, California; about 2 miles (airline) southeast from Mill Valley, 1,800 feet southwest from intersection of Hwy 1 and Panoramic Hwy, 200 feet east of fir road; latitude 122 degrees 33 feet 25 inches W. longitude 37 degrees 52 feet 50 inches N.
RANGE IN CHARACTERISTICS: Depth to a lithic contact is 11 to 20 inches. The mean annual soil temperature is 50 degrees to 56 degrees F. and the soil temperature is not below 47 degrees F. at any time. The soil is moist in some part from October until some time in August. Moist in the summer is due, in part, from heavy fog and low evapo-transpiration rates. It is dry in all parts less than 45 consecutive days in August and September. Gravel averages 35 to 50 percent and base saturation is 50 to 75 percent throughout the soil. Reaction is slightly acid or medium acid.
The A horizon has dry color of 10YR 5/2, 5/3, 4/2; 7.5YR 5/4 or 5/2 and moist color of 10YR 2/1, 2/2, 3/1, 3/2; 7.5YR 2/2 or 3/2. It is very gravelly sandy loam or very gravelly loam and has 1 to 3 percent organic matter.
The B horizon has dry color of 10YR 3/2, 4/3, 4/2, 5/2, 5/3; 7.5YR 4/2 or 4/4 and moist color of 10YR 2/1, 2/2, 3/1, 3/2, 3/3; 7.5YR 2/2 or 3/2.
COMPETING SERIES: This is the Bayview series in the same family and the McMullin and Tyson series. Bayview soils have siliceous shale rock fragments. McMullin soils have less than 35 percent rock fragments in the particle-size control section. Tyson soils have a lithic contact at a depth of 20 to 40 inches.
GEOGRAPHIC SETTING: Barnabe soils are on hills and mountainous uplands. Slopes are 9 to 75 percent. The soils formed on sandstone and shale. Elevations are 50 to 1,700 feet. The climate is subhumid mesothermal with cool foggy summers and cool moist winters. The mean annual precipitation is 30 to 50 inches. Mean January temperature is about 50 degrees F.; mean July temperature is about 56 degrees F., mean annual temperature is about 53 degrees F. Frost-free season is 275 to 360 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Centissima, Cronkhite, Dipsea and Henneke soils. Centissima, Cronkhite and Dipsea soils are more than 20 inches deep to a paralithic contact. Henneke soils have serpentinitic mineralogy and have an argillic horizon.
DRAINAGE AND PERMEABILITY: Well drained; medium to very rapid runoff; moderate permeability.
USE AND VEGETATION: Used for grassland, recreation and watershed. Native vegetation is annual grasses and forbs, lupine, plantain, thistle and brush.
DISTRIBUTION AND EXTENT: Central and northern coastal California. The soil is moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Marin County, California, 1979.
REMARKS: The activity class was added to the classification in January of 2003. Competing series were not checked at that time. - ET