LOCATION STARBRIGHT CAEstablished Series
TAXONOMIC CLASS: Fine, smectitic, isothermic Typic Argiustolls
TYPICAL PEDON: Starbright gravely loam, on a northeast facing 43 percent slope under a cover of oaks, toyon, crossosoma, ceanothus, lemonade sumac, and laurel sumac at an elevation of 1240 feet, (378 m). When described the soil was dry throughout. (Colors are for dry soil unless otherwise noted).
Oi--0 to 3 inches, (0 to 8 cm); slightly decomposed plant material; moderately acid (pH 5.8 by pH meter 1:1 water); abrupt smooth boundary. (0 to 8 centimeters thick)
A--3 to 8 inches, (8 to 20 cm); very dark grayish brown (10YR 3/2) broken face gravelly loam, very dark brown (10YR 2/2) broken face moist; 8 percent clay; strong medium subangular blocky structure; soft, friable, nonsticky, nonplastic; common fine roots throughout and common very fine roots throughout; 1 percent rounded 75 to 250 millimeter andesite fragments and 20 percent subangular 2 to 75 millimeter andesite fragments; moderately acid (pH 5.8 by pH meter 1:1 water) clear wavy boundary. (5 to 32 centimeters thick)
Bt1--8 to 12 inches, (20 to 30 cm); very dark grayish brown (10YR 3/2) broken face loam, very dark brown (10YR 2/2) broken face moist; 25 percent clay; strong medium subangular blocky structure; slightly hard, friable, slightly sticky, moderately plastic; common fine roots throughout and common medium roots throughout; faint clay films on all faces of peds; 5 percent subangular 2 to 75 millimeter andesite fragments; slightly acid (pH 6.5 by pH meter 1:1 water); clear wavy boundary. (5 to 50 centimeters thick)
Bt2--12 to 16 inches, (30 to 40 cm); very dark grayish brown (10YR 3/2) broken face clay loam, very dark brown (10YR 2/2) broken face moist; 38 percent clay; massive; hard, firm, very sticky, very plastic; common fine roots throughout and common medium roots throughout; prominent clay films on all faces of peds; 5 percent subangular 2 to 75 millimeter andesite fragments; neutral (pH 6.7 by pH meter 1:1 water); clear wavy boundary. (20 to 45 centimeters thick)
Bt3--16 to 28 inches, (40 to 70 cm); very dark grayish brown (10YR 3/2) broken face clay, very dark brown (10YR 2/2) broken face moist; 45 percent clay; massive; very hard, firm, very sticky, very plastic; common fine roots throughout and common medium roots throughout; prominent clay films on rock fragments; 10 percent subangular 2 to 75 millimeter andesite fragments; neutral (pH 7.0 by pH meter 1:1 water); clear wavy boundary. (0 to 30 centimeters thick)
Bt4--28 to 33 inches, (70 to 85 cm); brown (10YR 4/3) broken face clay loam, dark brown (10YR 3/3) broken face moist; 35 percent clay; weak fine subangular blocky structure; moderately hard, moderately sticky, moderately plastic; prominent clay films on all faces of peds and distinct clay films on rock fragments; 10 percent subangular 2 to 75 millimeter andesite fragments; neutral (pH 6.7 by pH meter 1:1 water); gradual wavy boundary. (0 to 20 centimeters thick)
Cr--33 to 35 inches, (85 to 90 cm); 95 percent strongly cemented, extremely hard andesite fragments with distinct clay films on rock fragments.
TYPE LOCATION: Santa Catalina Island, Los Angeles County, CA, in the Channel Islands Soil Survey Area 33 degrees, 22 minutes, 16.3 seconds North latitude and 118 degrees, 23 minutes, 0.7 seconds West longitude, NAD83 - U.S.G.S Quad: East Santa Catalina Island.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 15 to 17 degrees Celsius (59 to 63 degrees F.) The difference between mean summer and mean winter temperatures ranged from 4 to 5 degrees Celsius The soil moisture control section is dry in all parts from about mid-June to mid-November (about 150 days) and is usually moist in some part the rest of the time.
The A horizon dry color is 10YR 4/2, 3/2 2/2, 7.5YR 4/2. Moist color is 10YR 2/2, 7.5YR 2.5/2.
Textures are gravelly loamy, loam, silty clay loam.
Percent Clay is 8 to 25 percent.
Coarse fragments range 5 to 20 percent gravels.
The Bt1 horizon dry color is 10YR 4/3, 4/2, 3/2, 7.5YR 3/2. Moist color is 10YR 3/2, 2/2, 7.5YR 2.5/2.
Textures are loam, gravely clay loam, clay.
Percent Clay is 25 to 50 percent.
Coarse fragments are usually 5 to 15 percent gravels.
The Bt2 and Bt3 horizon dry color is 10YR 5/3, 3/2, 7.5YR 3/2. Moist color is 10YR 3/3, 2/2, 7.5YR 3/2.
Textures are clay loam, clay.
Percent Clay is 38 to 50 percent.
Coarse fragments are usually 5 to 10 percent gravels.
The Bt4 (bottom Bt) horizon dry color is 10YR 4/3. Moist color is 10YR 3/3.
Textures are silty clay loam, clay loam, gravely clay loam, clay, gravely clay, and extremely gravely clay.
Percent Clay is 30 to 50 percent.
Coarse fragments are usually 10 to 85 percent gravels.
The Cr material is extremely hard andesite fragments to lithic andesite with fractures greater than 10 cm apart. The upper portions of the fractured Cr material, commonly has distinct clay films on rock fragments and in some profiles would be described as fragmental. This should be considered when evaluating such properties as AWC.
Mollic Horizons range from 24 to 32 cm thick.
Argillic Horizons range from 40 to 90 cm thick.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Starbright soils are found on predominately north aspects and in the lower portions of landforms and drainageways under continuous stands of oak and island chaparral. They formed in residuum from andesite, rhyolite and basaltic rock on complex side slopes of interfluves of hills and mountains on islands. Slopes range from 10 to 65 percent. Elevations are from sea level to 1675 feet (0 to 511 meters). The climate is characterized by warm, dry summers and cool, moist winters with potential fog common all year. The mean annual precipitation ranges from 7 to 17 inches (178 to 432 mm), the mean annual temperature is 59 to 66 degrees F. (15 to 19 degrees C.), and the frost free season is 355 to 365 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Freeboard, Purser, Tongva, and Luff soils. Freeboard soils are deep. Freeboard and Luff soils are on linear and concave shapes of the upper and middle sideslopes under grass and sage communities. Purser soils are steep side slopes and are less than 50 cm to lithic rock. Tongva is fine-loamy, dominantly on convex and linear portions of sideslopes under sage communities.
DRAINAGE AND PERMEABILITY: Moderately well drained; medium runoff; moderate permeability.
USE AND VEGETATION: Wildlife habitat, recreation and building site development. Vegetation is predominately Island Chaparral and Coastal Sage Scrub, Oak woodland, Island Woodland, and Non-native Scrub.
DISTRIBUTION AND EXTENT: Santa Catalina Island, Los Angeles County, California. The soil is not extensive. MLRA 20.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California.
SERIES ESTABLISHED: Santa Catalina Island, Los Angeles County, California, 2006.
REMARKS: The series name is coined. Diagnostic horizons and features recognized in this pedon:
Bosun soils are isothermic borderline isomesic. The iso classification dictates the moisture regime to not be xeric. These soils are possibly in the Aridic subgroup. Moisture control section data is needed for this classification.
Mollic Horizon--The zone from the mineral surface to a depth of 30 cm
Argillic Horizon--The zone of clay accumulation between 20 cm and 85 cm or bedrock.