LOCATION AHOY CAEstablished Series
TAXONOMIC CLASS: Fine-loamy over clayey, mixed over smectitic, superactive, thermic Vertic Argixerolls
TYPICAL PEDON: Ahoy silt loam on a southwest facing 3 percent slope under a cover of ripgut and wild oats at an elevation of 465 feet on Santa Rosa Island, Santa Barbara County, CA. When described the soil was dry throughout. (Colors are for dry soil unless otherwise noted).
Oi--0 to 1 inche, (0 to 3 cm); slightly decomposed plant material; abrupt smooth boundary. (Horizon thickness ranges from 0 to 5 cm, 0 to 2 inches)
Oe--1 to 4 inches, (3 to 11 cm); moderately decomposed plant material with less than 30 percent mineral soil material; abrupt smooth boundary. (Horizon thickness ranges from 0 to 13 cm, 0 to 5 inches)
A--4 to 13 inches, (11 to 34 cm); brown (10YR 5/3) silt loam, very dark brown (10YR 2/2) moist; 15 percent clay; moderate medium subangular blocky structure; very hard, very friable, moderately sticky, moderately plastic; common very fine roots throughout; faint slickensides (pedogenic) and distinct clay films on all faces of peds and distinct clay films on surfaces along root channels; strongly acid (pH 5.5 by Phenol red); clear wavy boundary. (Horizon thickness ranges from 25 to 50 cm, 10 to 20 inches)
Bt1--13 to 21 inches, (34 to 52 cm); brown (7.5YR 4/3) silty clay loam, very dark brown (7.5YR 2.5/2) moist; 31 percent clay; moderate medium subangular blocky structure; moderately hard, very friable, very sticky, very plastic; common very fine roots throughout; distinct clay films on all faces of peds; strongly acid (pH 5.5 by Phenol red); gradual wavy boundary. (Horizon thickness ranges from 20 to 40 cm, 8 to 16 inches)
2Bt2--21 to 26 inches, (52 to 67 cm); light gray (10YR 7/1) very fine sandy loam, dark grayish brown (10YR 4/2) moist; 16 percent clay; moderate medium subangular blocky structure; moderately hard, very friable, slightly sticky, very plastic; common very fine roots throughout; distinct clay films on surfaces along root channels and distinct clay films on all faces of peds; moderately acid (pH 6.0 by Phenol red); diffuse wavy boundary. (Horizon thickness ranges from 8 to 23 cm, 3 to 9 inches)
3Bt3--26 to 33 inches, (67 to 84 cm); black (5Y 2.5/2) clay, very dark grayish brown (2.5Y 3/2) moist; 45 percent clay; moderate medium subangular blocky structure; hard, firm, very sticky, very plastic; common very fine roots throughout; distinct clay films on all faces of peds; slight effervescence; moderately acid (pH 6.0 by Phenol red); clear wavy boundary. (Horizon thickness ranges from 10 to 18 cm, 4 to 7 inches)
3Bss--33 to 47 inches, (84 to 152 cm);, black (5Y 2.5/2) clay, black (5Y 2.5/2) moist; 65 percent clay; massive; very hard, very firm, very sticky, very plastic; common very fine roots throughout; prominent slickensides (pedogenic) on vertical faces of peds; strong effervescence; neutral (pH 7.0 by Phenol red).
TYPE LOCATION: Santa Barbara County, California, in the Channel Islands Soil Survey Area 33 degrees North latitude, 59 minutes, 23.9 seconds and 120 degrees, 8 minutes, 44.8 seconds West longitude, NAD83. - U.S.G.S Quad: Santa Rosa Island.
RANGE IN CHARACTERISTICS:
The mean annual soil temperature is 59 to 64 degrees F. (15 to 18 degrees C.) The soil moisture control section is dry in all parts from about mid-August to mid-November (about 90 days) and is usually moist the rest of the time.
The particle size control section averages 27 to 40 percent clay in the upper part and 40 to 60 percent clay in the lower part.
Depth to contrasting particle-size discontinuity is 40 to 70 cm.
Vertical cracks range up to 10 mm in width and begin within 10 cm of the 2Bss horizon.
The A horizons dry color is 10YR 5/2, 5/3, 4/2, or 3/2. Moist color is 10YR, 3/2, 2/2.
The Bt1 and 2Bt2 horizons dry color is 10YR 7/2, 7/1, 6/3, 6/4, 6/2, 4/3. 2.5Y 2.5/2, 6/4. Moist color is 10YR 5/2, 4/2, 3/3, 4/4, 5/2. 7.5YR 2.5/2.
The 3Bt and 3Bss horizons dry color is 5Y 2.5/2, 2.5Y 4/2. Moist 5Y 3/2, 2.5Y 2.5/2, 3/2.
COMPETING SERIES: There are no competing soils in this family.
GEOGRAPHIC SETTING: Ahoy soils are on side slopes of hills and mountains of marine terraces on islands. These soils formed in material derived from weathered sandstone. Slopes are 2 to 30 percent. Elevations are 50 to 1000 feet (15 to 305 meters). The climate is characterized by warm, dry summers and cool, moist winters with fog common all year. The mean annual precipitation is 21 to 34 inches (533 to 864 mm), the mean annual temperature is 61 to 66 degrees F. (16 to 19 degrees C.), and the frost free season is 365 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Windage and Hawser soils. Hawser and Windage soils have no eolian sand deposits in the upper profile. Windage is generally found on steeper side slopes of mountains and hills. Hawser is found adjacent to Ahoy on the hills of the dissected marine terrace.
DRAINAGE AND PERMEABILITY: Moderately drained; generally low runoff except for rare steep slope areas; moderate to moderately slow permeability.
USE AND VEGETATION: Wildlife habitat, recreation and building site development. Vegetation is wild oats and miscellaneous forbs and grasses.
DISTRIBUTION AND EXTENT: Santa Barbra County and Los Angeles County, California. The soil is of limited extent and is only found on the Channel Islands. MLRA 20.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California.
SERIES ESTABLISHED: Santa Barbara County, California, 2005.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon--The zone from the soil surface to a depth of about 28 inches (48 cm).
Argillic horizon--The zone from a depth of 13 inches (33 cm) to a depth of about 47 inches (120 cm).
Multiple lithologic discontinuities resulting in abrupt textural changes and a dual particle size class.
Vertic material underlies eolian deposits, with vertical cracks up to 1 cm wide to a depth of 100 cm.