LOCATION BOSUN CAEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, isothermic Typic Argiustolls
TYPICAL PEDON: Bosun gravelly sandy loam, on a northerly facing 65 percent slope under a cover of oaks, toyon, , ceanothus, lemonade sumac, and laurel sumac at an elevation of 607 feet (185 meters). (Colors are for dry soil unless otherwise noted)
Oi--0 to 2 inches, (0 to 5 cm); slightly decomposed oak leaves and grass; loose; abrupt wavy boundary. (4 to 10 centimeters thick)
Oe--2 to 6 inches, (5 to 16 cm); moderately decomposed organic material; loose; abrupt wavy boundary. (0 to 9 centimeters thick)
A--6 to 14 inches, (16 to 35 cm); dark grayish brown (10YR 4/2) broken face gravelly sandy loam, very dark brown (10YR 2/2) broken face moist; 9 percent clay; weak fine subangular blocky and weak fine granular structure; loose, very friable, nonsticky, nonplastic; common fine roots and common medium roots and common very fine roots; common very fine interstitial pores; 18 percent rounded 2 to 75 millimeter gravel; neutral (pH 6.6); clear wavy boundary. (10 to 22 centimeters thick)
Bt1--14 to 24 inches, (35 to 60 cm); yellowish brown (10YR 5/6) broken face gravelly loam, yellowish brown (10YR 5/4) broken face moist; 25 percent clay; moderate medium subangular blocky structure; slightly hard, very friable, slightly sticky, moderately plastic; common fine roots and common medium roots; common very fine interstitial pores; few clay bridges between grains; 15 percent rounded 2 to 75 millimeter gravel; neutral (pH 7.2); clear wavy boundary. (19 to 30 centimeters thick)
Bt2--24 to 31 inches, (60 to 80 cm); yellowish brown (10YR 5/4) broken face very gravelly sandy clay loam, dark yellowish brown (10YR 4/4) broken face moist; 22 percent clay; weak fine subangular blocky structure; loose, very friable, slightly sticky, moderately plastic; common fine roots and common very fine roots; clay films on all faces of peds and clay films on rock fragments;5 percent angular 75 to 250 millimeter cobbles; 70 percent angular 2 to 75 millimeter gravel; slightly alkaline (pH 7.4); clear irregular boundary. (18 to 30 centimeters thick)
Bt3--31 to 47 inches, (80 to 120 cm); yellowish brown (10YR 5/4) broken face extremely gravelly sandy clay loam, dark yellowish brown (10YR 4/4) broken face moist; 20 percent clay; massive; loose, very friable, slightly sticky, moderately plastic; common fine roots and common very fine roots; clay films on all faces of peds and clay films on rock fragments; 20 percent angular 75 to 250 millimeter fragments and 80 percent angular 2 to 75 millimeter fragments; slightly alkaline (pH 7.4); clear irregular boundary. (0 to 40 centimeters thick)
Cr-- 47 inches, (120 to 120 cm); rigid, highly fractured, quartz-diorite porphyry; 44 percent angular 2 to 75 millimeter quartz-diorite fragments and 55 percent angular 75 to 250 millimeter fragments.
TYPE LOCATION: Santa Catalina Island, Los Angeles County, CA, in the Channel Islands Soil Survey Area; 33 degrees North latitude, 19 minutes, 54 seconds and 118 degrees, 19 minutes, 4 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 (includes A2 when present) dry color is 10YR 4/2. Moist color is 10YR 3/3, 2/2.
Textures are loam, gravely loam, sandy loam, gravely sandy loam.
Coarse fragments are usually 10 to 20 percent gravels.
Percent clay is 5 to 18.
The Bt1 horizon dry color is 10YR 5/6, 4/6, 7.5YR 5/4. Moist color is 10YR 5/4, 4/4, 7.5YR 4/4.
Textures are gravely loam, very gravely loam, very gravely sandy loam.
Coarse fragments are usually 15 to 45 percent with less than 10 percent cobbles.
Percent Clay is 18 to 25.
The Bt2 horizon dry color is 10YR 5/6, 4/6, 7.5YR 5/4. Moist color is 10YR 4/4, 7.5YR 4/4.
Textures are very gravely sandy clay loam, very gravely clay loam, extremely gravely sandy loam.
Coarse fragments are usually 45 to 85 percent with less than 10 percent cobbles.
Percent clay is 18 to 35.
The Bt3 horizon' when present, has dry color of 10YR 5/4, 2.5YR 6/6. Moist color is 10YR 4/4, 2.5YR 4/6.
Textures are extremely gravely sandy clay loam, very gravely clay loam, extremely gravely sandy loam.
Coarse fragments are usually 80 to 95 percent with less than 10 percent cobbles.
Percent clay is 20 to 38.
COMPETING SERIES: There are no other series in this family.
GEOGRAPHIC SETTING: Bosun soils are found on predominately north aspects under continuous stands of oak and chaparral. They formed in quartz-diorite and diorite porphyry on complex side slopes of interfluves of hills and mountains. This area contains some andesite dikes and fishers. Typically Bosun soils occur on lower portions of side slopes, concave shaped slopes and those where colluvium will accumulate. Slopes range from 35 to 75 percent. Elevations are from sea level to 1732 feet (0 to 528 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 Oboship, Nauti, Loadline, Flyer, Marpol and Express. Nauti soils are under sage and grass. Loadline soils are shallow and generally found on convex slope positions like crests of interfluves. Oboship and Express soils are coarse-loamy and predominately on the upper portions of slopes on interfluves.
DRAINAGE AND PERMEABILITY: Somewhat excessively drained; medium runoff; rapid permeability.
USE AND VEGETATION: Wildlife habitat, recreation and building site development. Vegetation is predominately Coastal Sage Scrub, Island Chaparral, and 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.
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.
Diagnostic horizons and features recognized in this pedon:
Mollic horizon--The zone from the soil surface to a depth of about 14 inches (35 centimeters) (A horizons). The O and surface A horizons are typically hydrophobic.
Argillic horizon--14 to 47 inches (35 to 120 cm)(Bt horizons).
The particle size class for this series is formed by both colluvium of coarse material and profiles residuum, where the fractured diorite is so prevalent it constitutes the majority of the profile.