LOCATION SOPER CAEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, thermic Typic Argixerolls
TYPICAL PEDON: Soper gravelly loam, scattered brush and annual grass rangeland. (Colors are for dry soil unless otherwise noted.)
Al--O to 8 inches; brown (10YR 4/3) gravelly loam, dark brown (7.5YR 3/2) moist; weak medium and coarse subangular blocky structure; slightly hard, friable, sticky and plastic; few fine and common very fine roots; common very fine tubular pres; 12 percent gravel and cobbles (by volume); slightly acid (pH 6.5); abrupt smooth boundary. (7 to 12 inches thick)
B21t--8 to 11 inches; reddish brown (5YR 5/4) gravelly clay loam, reddish brown (5YR 4/4) moist; moderate fine and medium subangular blocky structure; hard, firm, sticky and plastic- few fine and common Very fine roots; common fine and very fine tubular pores; common moderately thick clay films lining pores and on faces of peds; 25 percent gravel and cobbles (by volume); neutral (pH 6.7); clear smooth boundary. (4 to 8 inches thick)
B22t--11 to 21 inches; reddish brown (5YR 5/4) gravelly clay loam, reddish brown (5YR 4/4) moist; moderate fine and medium subangular blocky structure; hard, firm, sticky and plastic; few very fine and fine roots; few very fine tubular pores; many moderately thick clay films lining pores and on faces of peds; 30 percent gravel and cobbles (by volume); neutral (pH 6.7); clear smooth boundary. (6 to 12 inches thick)
B3--21 to 29 inches; yellowish red (5YR 5/6) gravelly loam, yellowish red (5YR 4/6) moist- weak medium and coarse angular blocky structure; hard, firm, slightly sticky and plastic; few very fine roots; few very fine tubular pores; few moderately thick clay filmg lining pores and on faces of peds; 30 percent gravel and cobbles (by volume); neutral (pH 6.7); clear wavy boundary. (3 to 8 inches thick)
Cr--29 to 62 inches; weakly consolidated conglomerate; few thin clay films on rock faces in upper part; gravel and cobbles composed of mixed crystalline rocks some strongly weathered.
TYPE LOCATION: Orange County, California; about 4,500 feet north-northwest of the spillway for, Rattlesnake Reservoir and 300 feet north of the Highland Canal, Irvine Range; N 1/4 N 1/4 sec. 82 (sections by private survey), T.5S., R.1W., SBBM. Topside of sections by this private survey are towards the northwest.
RANGE IN CHARACTERISTICS: Depth to a paralithic contact is 24 to 40 inches. The mean annual soil temperature is 60 degrees to 65 degrees F. at 20 inches depth and the soil temperature usually is not below 47 degrees F. at any time. The soil between depths of about 6 and 16 inches is continuously dry in all parts from late April or May until late October or November and usually is moist in some part all the rest of the year.
The A horizon is grayish brown, dark grayish brown, or brown in 10YR hue. It is loam or less commonly sandy loam and is commonly gravelly or cobbly with O to 20 percent rock fragments by volume. The horizon usually has weak or moderate granular or subangular blocky structure and is slightly hard or hard. In some pedons it is massive in some part and slightly hard. The A horizon is neutral to medium acid. It contains 1 to 4 percent organic matter to depth of about 10 inches and the amount decreases regularly to less than 1 percent at a depth of about 15 inches.
The B2t horizon is brown, dark brown or light yellowish brown in 10YR or 7.5YR hue or reddish brown in 5YR hue. It is gravelly or cobbly clay loam or gravelly or cobbly sandy clay loam and has 25 to 35 percent clay. This horizon is slightly acid to mildly alkaline. Some pedons have horizons transitional to the B2t horizon and have either or both Bl or B3 horizons. Some pedons have a C horizon above the paralithic contact that is gravelly or cobbly loam or gravelly or cobbly sandy loam.
COMPETING SERIES: These are the Ballard, Chualar, Gilroy and Pinto series. Dallard, Chualar and Pinto soils are deep and lack a paralithic contact. Gilroy soils have a lithic contact at depths of 20 to 40 inches.
GEOGRAPHIC SETTING: Soper soils are on hills and uplands with slopes of 15 to 50 percent and are at elevations of 100 to 2,500 feet. They formed in material weathered from conglomerate and sandstone. The climate is dry subhumid, mesothermal with warm to hot dry summers and cool moist winters. Mean annual precipitation is 12 to 25 inches. Mean annual temperature is 58 degrees to 65 degrees F. Average January temperature is abut 45 degrees to 5O degrees F. and July temperature is about 70 degrees to 75 degrees F. The frost-free season ia about 250 to 350 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Arnold, Azule, Balcom, Cieneba, Fontana, Gaviota, Los Gatos, Los Osos, Pleasanton, and Vallecitos soils. Arnold soils are sand or loamy sand and lack an argillic horizon. Azule and Los Osos soils have argillic hor;zons with more than 35 percent clay. Balcom soils lack an argillic horizon and are calcareous throughout. Cieneba soils have a paralithic contact at depths of less than 20 inches. Fontana soils lack an argillic horizon and have a Cca horizon. Gaviota soils have a lithic contact at depths of less than 20 inches. Los Gatos soils have a mean annual soil temperature of 54 degrees to 58 degrees F. Pleasanton soils lack a mollic epipedon and lack a paralithic contact above a depth of 40 inches. Vallecitos soils lack a mollic epipedon and have a lithic contact at depths of less than 20 inches in part of each pedon.
DRAINAGE AND PERMEABILITY: Well drained; rapid runoff; moderately slow permeability.
USE AND VEGETATION: Used for dryland pasture, rangeland, watershed, and homesites. Principal vegetation is annual and forbs, some native shrubs, and a few oak trees.
DISTRIBUTION AND EXTENT: Foothill areas in the western part of southern and central California. The soil 15 of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: San Bernardino County (Santa Ana Watershed), California, 1940.
REMARKS: In past mapping, Soper soils were not restricted to pedons having a paralithic contact at a depth of less than 40 inches.
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 6/76.