LOCATION OMSTOTT CAEstablished Series
TAXONOMIC CLASS: Loamy, mixed, superactive, nonacid, mesic, shallow Typic Xerorthents
TYPICAL PEDON: Omstott gravelly fine sandy loam - shrubs and annual grass cover. (Colors are for dry soil unless otherwise stated.)
Oi--0.33 to 0 inches; decomposing organic matter. Abrupt smooth boundary. (0 to 1/2 inch thick)
A11--0 to 4 inches; brown (10YR 5/3) gravelly fine sandy loam, dark brown (10YR 3/3) moist; weak medium subangular blocky structure; soft, friable, slightly sticky, nonplastic; few very fine roots; few very fine tubular pores; neutral (pH 7.0); clear wavy boundary. (3 to 6 inches thick)
A12--4 to 10 inches; dark brown (10YR 4/3) fine sandy loam, dark brown (10YR 3/3) moist; weak coarse subangular blocky structure; slightly hard, friable, slightly sticky, nonplastic; common very fine and few fine roots; common very fine tubular pores; neutral (pH 7.0); clear irregular boundary. (4 to 12 inches thick)
Cr--10 to 16 inches; dark yellowish brown (10YR 4/4) decomposing mica schist rubbing to gravelly fine sandy loam, brown (10YR 4/3) moist; massive, hard, slightly sticky, nonplastic; some finer material formed in place in cracks and cleavage planes; larger roots penetrate along joints; neutral (pH 6.6).
TYPE LOCATION: Riverside County, California; 4 1/4 miles north northwest of Intersection of Palm Canyon Dr. and Palms to Pines Highway 74; approximately 1 mile northwest of Asbestos Mountain; 1,080 feet north and 200 feet east of W1/4 corner section 21 T.6S., R.5E. SBBM.
RANGE IN CHARACTERISTICS: Mean annual soil temperature ranges from 55 degrees to 59 degrees F. Depth to a paralithic contact is 4 to 20 inches.
The Oi horizon is variable in thickness and intermittent and where it is absent a thin layer of fine gravel, very coarse or coarse sand is exposed.
The A horizons contain less than 1 percent organic matter and texture is coarse sandy loam to loam and may be gravelly.
The A11 horizon has hue of 10YR, value of 4 through 6 dry, 3 through 5 moist and chroma of 2 through 4 moist and dry. It is slightly acid to neutral.
The A12 horizon has hue of 10YR, value of 4 through 6 dry, 3 through 5 moist and chroma of 2 through 4 moist and dry. It has a clear or abrupt, smooth to irregular boundary to decomposing mica schist or granite with rock structure.
The Cr horizon is slightly acid to slightly alkaline.
COMPETING SERIES: These are the Cieneba, Crafton, Crouch, Sheephead, Tollhouse, Tyee, and Vista series. Cieneba and Vista soils have average annual temperatures above 95 degrees F. and Vista soils are more than 20 inches deep to a paralithic contact. Crafton, Crouch, Sheephead, and Tollhouse soils have a mollic epipedon. Also, Crafton and Crouch soils are more than 20 inches deep to a paralithic contact. Tyee soils have a mean annual precipitation of 12 to 30 inches and a mean annual soil temperature of 47 degrees to 55 degrees F.
GEOGRAPHIC SETTING: Omstott soils are on gently rolling to steep uplands at elevations of 3,600 feet to 5,000 feet. They formed in material weathered from granodiorite, mica schist and gneiss. The climate is semiarid with mean annual temperature of 53 degrees to 59 degrees F. with warm summers and cool moist winters, with small amounts of snow. Mean annual precipitation is 8 to 12 inches and the frost-free season (32 degrees F.+) is 120 to 180 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bull Trail, Cajon, Crouch and Tollhouse soils. Bull Trail soils have an argillic horizon and mollic epipedon. Cajon soils are warmer than 59 degrees F. and very deep. Crouch and Tollhouse soils have a mollic epipedon.
DRAINAGE AND PERMEABILITY: Well-drained; rapid to medium runoff; moderate and moderately rapid permeability.
USE AND VEGETATION: Omstott soils are used for watershed, wildlife, recreation and homesites. Vegetation is pine, pinyon pine, cedar, ribbonwood, ceanothus, scrub oak, manzanita, cholla, beavertail and barrel cactus, yucca, century plant, annual and perennial grasses.
DISTRIBUTION AND EXTENT: Southern California mountains. Series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Riverside County (Coachella Valley Area), California, 1974.
REMARKS: The activity class was added to the classification in February of 2003. Competing series were not checked at that time. - ET
OSED scanned by SSQA. Last revised by state on 5/74.