LOCATION PITVAR CAEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Typic Epiaquerts
TYPICAL PEDON: Pitvar clay on a west facing 1 percent slope under a cover of grasses and forbs, at an elevation of 4245 feet. (Colors are for dry soil unless, otherwise stated. When described October 3, 1984, the soil was slightly moist throughout.)
Ass--0 to 36 inches; brown (7.5YR 5/2) clay, dark brown (7.5YR 3/2) moist; strong coarse prismatic structure parting to strong fine angular blocky; extremely hard, extremely firm, very sticky and plastic; common fine roots; few very fine tubular pores; common intersecting slickensides; few very fine distinct black N 2/0 iron depletions; slightly alkaline (pH 7.5); clear smooth boundary. (30 to 40 inches thick)
Bss1--36 to 44 inches; brown (7.5YR 5/2) clay, brown (7.5YR 4/2) moist; moderate coarse prismatic structure parting to moderate coarse angular blocky; extremely hard, extremely firm, very sticky and very plastic; few fine roots; few very fine tubular pores; common intersecting slickensides; common very fine distinct black N 2/0 iron depletions; slightly alkaline (pH 7.5); gradual smooth boundary. (6 to 14 inches thick)
Bss2--44 to 55 inches; brown (7.5YR 5/4) silty clay, brown (7.5YR 4/4) moist; moderate coarse prismatic structure parting to moderate medium angular blocky; extremely hard, extremely firm, very sticky and very plastic, few very fine roots; few very fine tubular pores; common intersecting slickensides; common very fine distinct black N 2/0 iron depletions; slightly alkaline (pH 7.8); abrupt smooth boundary. (8 to 16 inches thick)
Bqm--55 to 58 inches; light brown (7.5YR 6/4) continuously indurated silica cemented duripan, brown (7.5YR 4/4) moist; few very fine distinct black (N 2/0) mottles; abrupt smooth boundary. (2 to 4 inches thick)
C--58 to 72 inches; light brown (7.5YR 6/4) clay loam, brown (7.5YR 4/4) moist; few very fine distinct black (N 2/0) mottles; moderate medium angular blocky structure; very hard, very firm, sticky and plastic; common very fine tubular pores; moderately alkaline (pH 8.0)
TYPE LOCATION: Modoc County, California; about 8 miles northwest of Lookout; 600 feet west and 1,600 feet south of the northeast corner of sec. 22, T. 40 N., R. 6 E., Whitehorse SE (Egg Lake) quadrangle (7.5 minute series).
RANGE IN CHARACTERISTICS: Depth to duripan is 50 to 60 inches. The mean annual soil temperature is 47 to 50 degrees F. The soil temperature exceeds 41 degrees F.
from mid March to late December (270 to 285 days) and exceeds 47 degrees F. from early May to early December. The soil moisture control section (6 to 18 inches) is dry in all parts from mid August to mid September (25 to 35 days) and is moist in all parts from late September to early July. The particle-size control section ranges from 40 to 60 percent clay. Surface cracks are 0.5 to 2 inches wide and extend to 20 to 25 inches deep. Some pedons have manganese shot in the Bss horizon.
The Ass horizon color is 7.5YR 4/2, 5/2, 10YR 4/2, or 5/2. Moist color is 7.5YR 3/2, 2/2; 10YR 3/2, or 4/2. Organic matter ranges from 1 to 2 percent. Clay content ranges from 40 to 50 percent.
The Bss horizon color is 7.5YR 5/2, 5/4; 10YR 4/2, or 5/2. Moist color is 7.5YR 4/2, 4/4, 6/4; 10YR 3/2,or 4/2. Texture is clay or silty clay. lay content ranges from 40 to 60 percent. Reaction ranges from slightly alkaline to moderately alkaline.
The Bqm horizon reaction ranges from slightly alkaline to moderately alkaline. Colors are similar to the C horizons.
The C horizon color is 7.5YR 5/4, 6/4, 5/6, or 6/6. Moist color is 7.5YR 4/4 or 4/6. Texture is clay loam or silty clay loam. Clay content ranges from 35 to 40 percent. Reaction ranges from slightly alkaline to moderately alkaline.
COMPETING SERIES: These are the Dosa (T CA) and Lasvar (T CA) soils. Lasvar soils are moderately deep to a duripan. Piline soils are very deep and lack a duripan. these soils Dosa?????
GEOGRAPHIC SETTING: Pitvar soils are in basins and in drainageways. Slopes are 0 to 2 percent. These soils formed in alluvium from extrusive igneous rock. Elevation is 3100 to 4800 feet. The climate is subhumid with warm dry summers and cold moist winters. Mean annual precipitation is 16 to 35 inches. Snowfall is 48 to 60 inches. The mean annual temperature is 45 to 48 degrees F. The mean January temperature is about 32 degrees F. The mean July temperature is about 65 degrees F. Frost-free season is 50 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Lasvar soil and Swanberger soils. Lasvar soils are in basins and are moderately deep. Swanberger soils are in basins, are very deep and do not crack for as long as 60 days.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; ponded or very slow runoff; slow permeability. A perched fluctuating water table occurs from the surface to 1 foot from December through April and from 1 to 3 feet from April through July and is below 40 inches from August through October. Ponding occurs from 9 to 12 inches above the surface from December through April.
USE AND VEGETATION: This soil is used for livestock grazing, pasture and crops. The natural vegetation is yampah, danthonia, bluegrass, rushes and sedges and some silver sagebrush.
DISTRIBUTION AND EXTENT: Northeastern California. The soils are not extensive. MLRA is 22.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Modoc County, Intermountain Soil Survey Area, California 1994. Source of name is coined.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon- the zone from the soil surface to about 36 inches. (Ass horizon)
Duripan- the zone from 55 to 58 inches (Bqm)