LOCATION CENTISSIMA CA

Established Series
Rev. TAC/JHK/JMK/TDC
02/2023

CENTISSIMA SERIES

The Centissima series consists of moderately deep, well drained soils that formed in material weathered from fine grained sandstone and shale. Centissima soils are on hills and mountainous uplands and have slopes of 15 to 75 percent. The mean annual precipitation is about 48 inches and the mean annual temperature is about 54 degrees F.

TAXONOMIC CLASS: Fine-loamy, mixed, active, isomesic Humic Dystrustepts

TYPICAL PEDON: Centissima loam, on a S. W. facing convex slope of 20 percent slopes under Douglas-fir, tanoak, poison-oak, swordfern, bay, and some annual grasses at 920 feet elevation. (Colors are for dry soils unless otherwise stated. When described on 8/14/76, the soil was moist below 6 inches.)

O--2 inches to 0; decomposed duff and litter.

A11--0 to 6 inches; brown (10YR 4/3) loam, very dark grayish brown (10YR 3/2) moist; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine, fine, medium and coarse roots; many very fine and fine interstitial and tubular, few medium interstitial and tubular pores; slightly acid (pH 6.5); gradual wavy boundary. (3 to 6 inches thick)

A12--6 to 15 inches; brown (10YR 4/3) loam, very dark grayish brown (10YR 3/2) moist; moderate fine and medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine, fine, medium and coarse roots; many very fine and fine interstitial and tubular, few medium interstitial and tubular pores; slightly acid (pH 6.5); clear irregular boundary. (5 to 10 inches thick)

B2t--15 to 22 inches; light yellowish brown (10YR 6/4) loam, dark yellowish brown (10YR 3/4) moist; moderate fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few fine and medium roots; many very fine and fine interstitial and tubular, few medium interstitial and tubular pores; few thin clay films on peds and in pores; moderately acid (pH 6.0); clear irregular boundary. (5 to 8 inches thick)

C1--22 to 29 inches; light brown (7.5YR 6/4) gravelly clay loam, yellowish brown (10YR 5/4) moist; weak fine and medium subangular blocky structure; hard, firm, sticky and plastic; few fine and medium roots; many very fine and fine interstitial and tubular pores; few thin clay films on eds and in pores; 20 percent pebbles; moderately acid (pH 6.0); clear wavy boundary. (4 to 9 inches thick)

C2--29 to 33 inches; light brown (7.5YR 6/4) and yellowish red (5YR 5/6) very gravelly clay loam, strong brown (7.5YR 5/6) moist; weak fine and medium subangular blocky structure; hard, firm, sticky and plastic; few fine and medium roots; common very fine and fine interstitial and tubular pores; common thin clay films on peds and in pores; 45 percent pebbles; slightly acid (pH 6.3); clear smooth boundary. (3 to 7 inches thick)

C3r--33 to 40 inches; massive weathered soft sandstone and shale. Slakes in water.

TYPE LOCATION: Marin County, California; 0.8 mile NE on Randall trail from Hwy 1, 20 feet south of Randall trail, in the Golden Gate National Recreational Area, 122 degrees 42 feet 42 inches W. Latitude, 37 degrees 58 feet 50 inches N. Longitude.

RANGE IN CHARACTERISTICS: Depth to a paralithic contact is 20 to 40 inches. The mean annual soil temperature is 50 degrees to 56 degrees F. The difference between mean annual winter and mean annual summer temperature is less than 9 degrees F. The soil moisture control section is moist in all parts about 270 to 300 days. Reaction is slightly acid to medium acid. Base saturation is less than 50 percent throughout and decreases as depth increases.

The A horizon is dark grayish brown or brown (10YR 4/2, 4/3, 5/3; 7.5YR 3/2, 4/2, 4/4, 5/2). Moist color is very dark grayish brown or dark brown (10YR 3/2, 3/3; 7.5YR 3/2). This horizon is gravelly loam, loam, fine sandy loam, or gravelly fine sandy loam.

The B horizon is light yellowish brown, brownish yellow, or pale brown (10YR 6/3, 6/4, 6/6). Most color is dark brown, dark yellowish brown or yellowish brown (10YR 3/3, 3/4, 4/4, 5/4, 5/6). This horizon is loam or gravelly loam. There is a 1 to less than 3 percent increase in clay content from the A horizon to the B horizon.

The C horizon is light brown, reddish yellow, light yellowish brown, or brownish yellow (7.5YR 6/4, 6/6; 10YR 6/4, 6/6). Moist color is brown, strong brown, yellowish brown or yellowish red (7.5YR 5/4, 5/6; 10YR 5/4, 5/6; 5YR 4/6). The upper part of the C horizon is loam or gravelly clay loam. The upper part ranges from 5 to 35 percent gravel and the lower part from 35 to 50 percent gravel.

COMPETING SERIES: This is the Palomarin series in the same family and the Sirdrak and Wittenberg series. Palomarin soils are 40 to 60 inches deep to a lithic contact. Sirdrak soils have a sandy control section. Wittenberg soils are 40 to 60 inches deep to a lithic contact and have a loamy-skeletal control section.

GEOGRAPHIC SETTING: Centissima soils are on hills and mountains. Slopes are 15 to 75 percent. The soils formed in material weathered from fine grained sandstone and shale. Elevation are from 500 to 1,700 feet. The climate is subhumid mesothermal with cool foggy summers and cool moist winters. The mean annual precipitation is 40 to 50 inches. Mean January temperature is about 49 degrees F.; mean July temperature is about 57 DEGREES F.; mean annual temperature is about 54 degrees F. Frost-free season is 300 to 365 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Barnabe, Cronkhite, Dipsea and Henneke soils. Barnabe soils are less than 20 inches deep to a lithic contact. Dipsea and Cronkhite soils have an argillic horizon. Henneke soils have serpentinitic mineralogy and average more than 35 percent gravel in the particle-size control section.

DRAINAGE AND PERMEABILITY: Well drained; rapid to very rapid runoff; moderate permeability.

USE AND VEGETATION: Used for woodland, wildlife habitat and watershed. Native vegetation is Douglas-fir, madrone, redwood, huckleberry, ferns, clover, moss dogwood and Tanbark oak.

DISTRIBUTION AND EXTENT: Central and northern coastal California. The series is of small extent.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California

SERIES ESTABLISHED: Marin County, California, 1979.

National Cooperative Soil Survey
U.S.A.