LOCATION FRIGATE CAEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, isomesic Typic Haploxerepts
TYPICAL PEDON: Frigate loam on a hill side under a Bishop pine forest on Santa Cruz Island, at an elevation of 1245 feet (380 meters). (Colors are for dry soil unless otherwise noted).
Oe--0 to 3 inches, (0 to 7 cm); moderately decomposed pine needles; clear smooth boundary. (1 to 6 inches thick (2 to 15 centimeters))
A1--3 to 4 inches, (7 to 10 cm); brown (10YR 4/3) silt loam, dark brown (10YR 3/3) moist; 10 percent clay; moderate fine granular and moderate medium granular structure; slightly hard, very friable, slightly sticky, slightly plastic; many very fine roots and common fine roots and common medium roots and common coarse roots; moderately hydrophobic; 10 percent gravel; slightly acid, pH 6.2 by Phenol red; clear smooth boundary. (1 to 8 inches thick (2 to 20 centimeters))
Bt1--4 to 8 inches, (10 to 21 cm); brown (7.5YR 4/3) and strong brown (7.5YR 5/6) gravelly silt loam, strong brown (7.5YR 4/6) and dark brown (7.5YR 3/3) moist; 13 percent clay; moderate medium subangular blocky structure; slightly hard, very friable, slightly sticky, slightly plastic; many very fine roots and few fine roots and common medium roots; 12 percent discontinuous clay films on ped faces; 25 percent gravel; moderately acid, pH 6.0 by Phenol red; clear wavy boundary. (0 to 6 inches thick (0 to 15 centimeters))
Bt2--8 to 15 inches, (21 to 39 cm); strong brown (7.5YR 5/6) gravelly silt loam, strong brown (7.5YR 4/6) moist; 16 percent clay; moderate medium subangular blocky structure; slightly hard, very friable, slightly sticky, slightly plastic; common fine roots and few fine roots and few medium roots and few coarse roots; few vesicular pores; few discontinuous clay films on ped faces; 25 percent gravels; slightly acid, pH 6.4 by Phenol red; clear wavy boundary. (5 to 12 inches thick (13 to 31 centimeters))
Bt3--15 to 28 inches, (39 to 71 cm); yellowish brown (10YR 5/4) extremely gravelly silt loam, brown (7.5YR 4/4) moist; 12 percent clay; moderate medium subangular blocky structure; slightly hard, very friable, slightly sticky, slightly plastic; few very fine roots few medium roots; few vesicular pores; few thin clay bridging sand grains; 55 percent gravels; moderately acid, pH 5.8 by Phenol red; clear wavy boundary. (4 to 12 inches thick (10 to 31 centimeters))
Bt4--28 to 31 inches, (71 to 79 cm); reddish brown (5YR 5/4) very gravelly silt loam, reddish brown (5YR4/4) moist; 18 percent clay; moderate medium subangular blocky structure; slightly hard, very friable, slightly sticky, slightly plastic; few fine roots; few thin clay bridging sand grains; 50 percent gravel; moderately acid, pH 5.8 by Phenol red; clear wavy boundary. (4 to 12 inches thick (10 to 31 centimeters))
Cr--31 to 67 inches, (79 to 170 cm); soft schist, fractures less than 10 cm apart. (15 to 40 inches thick (38 to 102 centimeters))
R--67 inches, (170 cm); very hard schist, fractures greater than 10 cm apart.
TYPE LOCATION: Santa Cruz Island, Santa Barbara County, California, in the Channel Islands Soil Survey Area in the Christy Pine Forest at 34 degrees, 00 minutes, 42.6 seconds North latitude and 119 degrees, 48 minutes, 5.2 seconds West longitude, NAD83; USGS Quad: Santa Cruz Island.
RANGE IN CHARACTERISTICS:
The mean annual soil temperature is 54 to 59 degrees F. (12 to 15 degrees C.) The difference in soil temperature between mean summer and mean winter is less than 6 degrees C. The soil moisture control section is dry in all parts from about mid-September to mid-November (about 90 days) and is usually moist the rest of the time.
Depth to bedrock is 20 to 40 inches (50 to 100 centimeters).
The particle size control section averages 10 to 18 percent clay and 15 to 35 percent rock fragments.
Reaction is slightly acid to moderately acid.
The A horizon color is 10YR or 7.5YR 4/3, 5/4, 5/6, 6/2, or 6/3 dry. Moist color is 10YR or 7.5YR 5/3, 4/3, 4/6, 3/3 or 2/2.
The Bt horizon color is 10YR, 7.5YR, or 5YR 6/3, 6/3, 5/4 or 5/6 dry. Moist color is 10YR or 7.5YR 5/4, 5/6, 4/6 or 4/4 moist.
Textures are silt loam, gravelly silt loam, very gravelly silt loam, overy gravelly loam or extremely gravelly silt loam.
Bt horizon commonly has clay films but lacks enough clay increase for an argillic horizon.
Rock fragments range from 5 to 60 percent.
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COMPETING SERIES: There are no competing soils in this family.
GEOGRAPHIC SETTING: Frigate soils are on northerly side slopes of hills on islands. Slopes range from 30 to 75 percent. The soils formed in weathered schist. The elevations are 500 to 1310 feet (152 to 400 meters). The climate is characterized by warm, dry summers and cool, moist winters with fog common all year. The mean annual precipitation is 13 to 24 inches (330 to 610 mm), the mean annual temperature is 55 to 61 degrees F. (13 to 16 degrees C.), and the frost free season is 320 to 265 days.
GEOGRAPHICALLY ASSOCIATED SOILS: This is the Yardarm and Miasotus series. Yardarm has mollic epipedons and a fine-loamy particle size family. Miasotus soils are shallow to bedrock and have argillic horizons. Both these soils are on the side slopes of hills.
DRAINAGE AND PERMEABILITY: Well drained; runoff is high; moderate permeability.
USE AND VEGETATION: Wildlife habitat, recreation and building site development. Vegetation is Bishop Pines.
DISTRIBUTION AND EXTENT: Santa Barbara County, California on Santa Cruz Island. The soil is not extensive. MLRA 20.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California.
SERIES ESTABLISHED: Santa Barbara County, California, 2004.
REMARKS: The series name is coined. Isomesic is indicated from data gathered from NRCS Soil Temperature/Soil Moisture climate stations on Santa Cruz Island. National Soil Survey Laboratory Pedon number 05N0102, Diagnostic horizons and features recognized in this pedon:
Ochric epipedon--The zone from the soil surface to a depth of about 4 inches (A horizon).
Cambic horizon--The zone from a depth of 8 inches to a depth of about 15 inches (Bt horizon).
Paralithic material--The zone from a depth of 31 inches to about 67 inches (Crt horizon)