LOCATION WHITEROCK CAEstablished Series
TAXONOMIC CLASS: Loamy, mixed, superactive, nonacid, thermic Lithic Xerorthents
TYPICAL PEDON: Whiterock loam - on a 7 percent convex southwest facing slope under annual grasses and forbs at an elevation of 390 feet. When described September 28, 1982, the soil was moist throughout. (Colors are for dry soil unless otherwise stated)
A1--0 to 1 inch; pale brown (10YR 6/3) loam, brown (10YR 4/3) moist, weak fine platy structure, slightly hard, friable, nonsticky, and nonplastic; many fine and common very fine roots; common very fine interstitial and common very fine and fine tubular pores; 1/4 inch thick mat of decomposed litter at surface; 10 percent angular pebbles, strongly acid (pH 5.2); abrupt smooth boundary. (1 to 3 inches thick)
A2--1 to 8 inches; very pale brown (10YR 7/3) loam, brown (10YR 4/3) moist; massive; slightly hard, friable, slightly sticky and nonplastic; common very fine roots; few very fine interstitial and common very fine tubular pores; 10 percent angular pebbles, moderately acid (pH 5.9); abrupt irregular boundary. (3 to 11 inches thick)
R--8 to 12 inches; highly fractured and vertically tilted metasedimentary rock; common very fine roots between fractures, fractures 1/4 to 1 1/2 inches apart.
TYPE LOCATION: Sacramento County, California; about 4.3 miles southwest of Clarksville, 2.5 miles west of Malby Crossing, 1,500 feet west of junction of Whiterock Road and Scott Road, 600 feet north of Whiterock Road, 3,550 feet north and 1,500 feet west of the southeast corner of section 20, T.9 N., R.8 E.
RANGE IN CHARACTERISTICS: Depth to a lithic contact is 4 to 14 inches. Mean annual soil temperature is 63 to 67 degrees F and the soil temperature remains above 47 degrees F at all times. The soil below a depth of 7 inches usually is dry all of the time after late April or May until November and usually is continuously moist all the rest of the year. Content of angular coarse fragments, mostly 1/4 to 1 1/2 inches in diameter, is 5 to 35 percent. Coarse fragments usually are more numerous in the lower part of the soil profile. Base saturation (Ammonium acetate) is 60 to 80 percent throughout.
The A horizon is 10YR 6/2, 6/3, 6/4, 7/2, 7/3, 8/2; 2.5Y 6/2, 7/2, or 8/2. Moist color is 10YR 4/2, 4/3, 5/2, 5/3; 2.5Y 4/2, or 5/2. The upper 1/2 to 1 1/2 inches is 10YR 4/2, 5/2, 5/3, or 5/4 in some pedons. Moist color is 10YR 3/2, or 3/3. Texture is loam or silt loam with 12 to 25 percent clay and 25 to 50 percent sand. Organic matter content in the upper 1/2 to 1 1/2 inches is 2 to 6 percent and is less than 2 percent below this depth. The upper few inches of the A horizon has platy or granular structure or the horizon is massive throughout. Reaction is strongly acid or moderately acid but is always moderately acid in some or all parts of the pedon.
COMPETING SERIES: These are the Daulton, Exchequer, Gaviota, Ocraig and Snook soils. Daulton and Exchequer soils have an epipedon with a dry value of 3 to 5 in all parts. Exchequer soils also have moist chromas of 4 to 8. Gaviota soils have greater than 50 percent sand and a lithic contact that lacks fractures. Ocraig soils have a coarse plus very coarse sand content of greater than 20 percent. Snook soils have mean annual soil temperatures of 59 to 62 degrees F.
GEOGRAPHIC SETTING: The Whiterock soils are on foothills at elevations of 160 to 2,500 feet. Slopes are 3 to 60 percent. The soils formed in material weathered from slate and partially metamorphosed sandstone. These metasedimentary rocks of the Mariposa Formation are nearly vertically tilted and slab like rock outcrops are common. The climate is subhumid with hot dry summers and cool, moist winters. Mean annual precipitation is 12 to 30 inches. Mean annual temperature is about 60 to 63 degrees F; average January temperature is about 42 to 47 degrees F and average July temperature is about 77 to 82 degrees F. The frost-free season is 175 to 290 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Daulton and Exchequer soils and the Amador, Argonaut, Auburn and Hornitos soils. Amador soils have a paralithic contact and are on hills. Argonaut soils have an argillic horizon and a paralithic contact at a depth of 20 to 40 inches and are commonly in concave positions. Auburn soils have a cambic horizon and a depth to a lithic contact greater than 20 inches in part of each pedon. Hornitos soils have a cambic horizon and are on hills.
DRAINAGE AND PERMEABILITY: Somewhat excessively drained, slow to rapid runoff, moderate permeability.
USE AND VEGETATION: Used for annual rangeland and watershed. Native vegetation is blue oak, soft chess, foxtail fescue, ripgut brome and filaree with widely spaced live oak and thickets of brush.
DISTRIBUTION AND EXTENT: Foothills on the east side of Sacramento and San Joaquin Valleys, California. The series is of moderate extent.
MLRA OFFICE RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Sacramento County (Sacramento Area), California, 1946.
REMARKS: This new typical pedon is within a mile of the original type location. The Whiterock soils were formerly classified as loamy, mixed, acid, thermic Lithic Xerorthents. Data from published soil survey reports and from the new type location do not support the former classification.
The activity class was added to the classification in March of 2003. Competing series were not checked at that time. - ET
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from the surface to 8 inches (A1, A2 horizons).
Lithic contact - at a depth of 8 inches (R) vertically tilted fractures are 1/4 to 1 and 1/2 inches apart. Fragments of rock do not slake in water.
ADDITIONAL DATA: This pedon sampled for complete characterization by Lincoln, Nebraska NSSL in 1982. Pedon number is S82-CA-067-3-1 through 2.