LOCATION FORESTAY CAEstablished Series
TAXONOMIC CLASS: Clayey-skeletal, smectitic, mesic Ultic Palexerolls
TYPICAL PEDON: Forestay on a hill side a cover of scrub oaks and live oaks at an elevation of 1240 feet (378 meters) on Santa Cruz Island. (Colors are for dry soil unless otherwise noted).
Oi--0 to 2 inches, (0 to 5 cm); slightly decomposed oak liter; strongly acid, pH 5.3 by pH meter, saturated paste; clear wavy boundary. (0 to 3 inches thick, 0 to 7 centimeters)
A1--2 to 4 inches, (5 to 10 cm); very dark grayish brown (10YR 3/2) gravelly loam, black (10YR 2/1) moist; 26 percent clay; weak fine subangular blocky structure; slightly hard, very friable, slightly sticky, slightly plastic; 15 percent 2 to 75 millimeter gravel; base saturation is 48 percent; strongly acid, pH 5.4 by pH meter, saturated paste; clear smooth boundary.
A2--4 to 15 inches, (10 to 38 cm); dark grayish brown (10YR 4/2) gravelly loam, very dark brown (10YR 2/2) moist; 22 percent clay; moderate fine subangular blocky structure; slightly hard, very friable, slightly sticky, slightly plastic; 20 percent 2 to 75 millimeter gravel; base saturation is 73 percent; slightly acid, pH 6.4 by pH meter, saturated paste; clear smooth boundary. (10 to 20 inches thick, 25 to 50 centimeters)
2Bw--15 to 27 inches, (38 to 68 cm); brown (10YR 5/3) very gravelly coarse sandy loam, dark brown (10YR 3/3) moist; 19 percent clay; moderate medium angular blocky structure; soft, very friable, nonsticky, nonplastic; 35 percent 2 to 75 millimeter gravel; base saturation is 59 percent; strongly acid, pH 5.5 by pH meter, saturated paste; clear smooth boundary. (5 to 15 inches thick, 13 to 38 centimeters)
3Bt1--27 to 35 inches, (68 to 89 cm); very dark gray (10YR 3/1) extremely gravelly clay, black (10YR 2/1) moist; 56 percent clay; moderate medium angular blocky structure; moderately hard, firm, very sticky, very plastic; continuous prominent clay films on all faces of peds and rock fragments; 60 percent 2 to 75 millimeter gravel; base saturation is 43 percent; extremely acid, pH 4.4 by pH meter, saturated paste; clear smooth boundary.
3Bt2--35 to 45 inches, (89 to 115 cm); very dark gray (10YR 3/1) gravelly clay, black (10YR 2/1) moist; 52 percent clay; moderate medium angular blocky structure; moderately hard, firm, very sticky, very plastic; continuous prominent clay films on all faces of peds and rock fragments; 25 percent 2 to 75 millimeter gravel; base saturation is 38 percent; extremely acid, pH 4.3 by pH meter, saturated paste; clear smooth boundary.
3Bt3--45 to 60 inches, (115 to 152 cm); very dark gray (10YR 3/1) extremely gravelly clay, black (10YR 2/1) moist; 51 percent clay; moderate medium angular blocky structure; moderately hard, firm, very sticky, very plastic; continuous prominent clay films on all faces of peds and rock fragments; 60 percent 2 to 75 millimeter gravel; base saturation is 41 percent; extremely acid, pH 4.2 by pH meter, saturated paste. (Combined thickness of Bt horizons is 20 to 40 inches, 51 to 102 centimeters)
TYPE LOCATION: Santa Cruz Island, Santa Barbara County, CA, in the Channel Islands Soil Survey Area 33 degrees North latitude, 59 minutes, 50 seconds and 119 degrees, 39 minutes, 58 seconds West longitude, NAD83; U.S.G.S Quad: Santa Cruz Island.
RANGE IN CHARACTERISTICS:
The mean annual soil temperature is 53 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 60 days) and is usually moist the rest of the time.
Depth to bedrock is greater than 60 inches (152 centimeters).
Depth to abrupt clay increase is 6 to 28 inches (15 to 70 centimeters). High variability of depth to clay is due to disturbance and erosion caused by animals, mostly wild pigs.
Base saturation by sum of bases ranges from 38 to 73 percent.
Depth to lithologic discontinuity ranges from 6 to 22 inches, but does not occur in all pedons. Mollic epipedon thickness is always more than 15 inches (38 centimeters) often extending into the argillic horizon.
The particle size control section averages 40 to 60 percent clay and 35 to 60 percent rock fragments. Organic matter ranges from 1 to 4 percent to a depth of at least 20 inches (50 centimeters). Reaction is extremely acid to neutral throughout the profile.
The A horizon dry color is 10YR 4/2 or 3/2. Moist color is 10YR 3/2, 2/2, or 2/1.
The Bt horizon dry color is 10YR 5/2, 5/3, 4/2, or 3/1. Moist color is 10YR 3/3, 3/2, 2/1 or 2/2.
Clay content ranges from 30 to 60 percent.
Textures are dominantly very gravelly clay with some gravelly clay, extremely gravelly clay, gravelly clay loam, and very gravelly clay loam.
COMPETING SERIES: This is the Tekison series. Tekison soils do not have Bw horizons with very gravelly coarse sandy loam textures, do not have lithologic discontinuities, and have mean annual soil temperatures of 47 to 49 degrees F.
GEOGRAPHIC SETTING: Forestay soils are on side slopes and summits of hills that formed on uplifted marine deposits on Santa Cruz Island. Slopes range from 2 to 60 percent. The soils formed in shale. The elevations are 300 to 1400 feet (28 to 427 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 365 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Fantail, and Lospinos soils. Both these soils are moderately deep to bedrock on hills.
DRAINAGE AND PERMEABILITY: Well drained; high to very high runoff; slow permeability.
USE AND VEGETATION: Wildlife habitat, recreation and building site development. Vegetation is coast live oak, scrub oak and annual grasses.
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. National Soil Survey Laboratory Pedon number is 05N0104. Diagnostic horizons and features recognized in this pedon:
Mollic epipedon--The zone from the soil surface to a depth of about 15 inches.
Cambic horizon--The zone from a depth of 15 inches to a depth of about 27 inches.
Argillic horizon--The zone from a depth of 27 inches to a depth of about 60 inches.