LOCATION PIT CA+OREstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Xeric Endoaquerts
TYPICAL PEDON: Pit silty clay - on a less than 1 percent slope under sedges, tuffed hairgrass and alpine timothy at 4,115 feet elevation. (Colors are for dry soil unless otherwise stated.)
A1--0 to 2 inches; dark gray (10YR 4/1) silty clay, black (10YR 2/1) moist; strong very fine granular structure; very hard, friable, sticky and very plastic; common very fine and fine roots; many fine interstitial pores; cracks 1 1/2 inches wide; neutral (pH 7.0); abrupt smooth boundary. (1 to 3 inches thick)
A2--2 to 4 inches; dark gray (10YR 4/1) silty clay, black (10YR 2/1) moist; moderate thin platy structure; very hard, friable, sticky and very plastic; common very fine and fine roots; many very fine tubular pores; cracks 1 1/2 inches wide; neutral (pH 7.0); clear smooth boundary. (1 to 4 inches thick)
Bss--4 to 22 inches; dark gray (10YR 4/1) clay, very dark gray (10YR 3/1) moist; strong coarse prismatic structure; very hard, very firm, sticky and very plastic; common very fine and fine, and few coarse exped roots, roots, and common very fine roots; common very fine tubular pores; cracks 1/2 inch wide in lower part; many intersecting slickensides; slightly alkaline (pH 7.4); clear wavy boundary. (16 to 26 inches thick)
Bk1--22 to 40 inches; dark gray (10YR 4/2) clay, very dark brown (10YR 2/2) moist; strong medium angular blocky structure; very hard, firm, sticky and very plastic; many very fine and common fine tubular pores; violently effervescent, lime in seams and soft masses; moderately alkaline (pH 8.0); clear wavy boundary. (14 to 19 inches thick)
Bk2--40 to 45 inches; light brownish gray (10YR 6/2) silty clay loam, dark grayish brown (10YR 4/2) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; few very fine roots; many very fine tubular pores; violently effervescent, lime in seams and soft masses; moderately alkaline (pH 8.0); clear smooth boundary. (4 to 8 inches thick)
C--45 to 60 inches; light brownish gray (10YR 6/2) silt loam, dark grayish brown (10YR 4/2) moist; massive; slightly hard, friable, nonsticky and slightly plastic; few very fine roots; many very fine and fine tubular pores; few fine distinct dark yellowish brown (10YR 3/4) masses of iron accumulation; slightly alkaline (pH 7.5).
TYPE LOCATION: Lassen County, California; about 1 mile southwest of Bieber; 1200 feet east and 600 feet north of the southwest corner of section 22, T.38S., R.7E., Bieber SW (Bieber) Quadrangle (7.5 minute series)
RANGE IN CHARACTERISTICS: Mollic epipedon and depth to carbonates is 20 to 26 inches. The mean annual soil temperature is 47 to 54 degrees F. The soil has cracks 1 to 5 cm wide at a depth of 20 to 26 inches. The cracks open and close once each year. They remain open during the period of July through October and remain closed the rest of the year. Common to many intersecting slickensides are in all or part of the Bss horizon.
The A and Bss horizon colors is 10YR 3/1, 4/1, 4/2, 5/1, 5/2; N3/0, N4/0, and N5/0. Moist color is 10YR 2/1, 3/1; N2/0, and N3/0. Texture is silty clay loam, silty clay or clay. Reaction is neutral or slightly alkaline.
The Bk horizon color is 10YR 4/1, 4/2, 5/1, 6/2; and 2.5Y 4/2. Moist colors are 10YR 2/2, 3/2, 4/2; and 2.5Y 3/2 moist. They are silty clay loam, silty clay, or clay with 35 to 60 percent clay. Reaction is slightly alkaline or moderately alkaline. Segregated lime occurs as soft masses or in seams.
The C horizon color is 10YR 4/3, 4/2, 5/3, 5/2, 6/3, 6/2; 2.5Y 4/2, 5/2, 6/2; 5Y 6/3, and 7/2. Moist color is l0YR 3/2, 3/3, 4/2, 4/3; 2.5Y 3/2, 4/2 or and 5Y 4/2. Distinct or prominent mottles are present in some part of this horizon below a depth of 40 inches. It is silt loam, sandy clay loam, clay loam or silty clay loam. It is mildly alkaline or moderately alkaline and in most pedons is calcareous.
COMPETING SERIES: These are the Cardon (UT) and Fenn (ID) series. Cardon soils lack Bk horizons and have mollic epipedons that are 10 to 15 inches thick. Fenn soils have Bk horizons that are 30 or more inches thick, lack high water tables and are usually dry for 60 to 90 days.
GEOGRAPHIC SETTING: Pit soils are on flood plains and in basins. Slopes are 0 to 5 percent. The soils formed in alluvium from extrusive and basic igneous rocks. Elevations are 2,500 to 5,300 feet. The climate is characterized as having warm dry summers and cold moist winters. Mean annual precipitation is 8 to 18 inches. Seasonal snowfall is 12 to 36 inches. Mean January temperature is 27 to 30 degrees F; mean July temperature is 67 to 70 degrees F; and mean annual temperature is 44 to 52 degrees F. Frost-free period is 60 to 140 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bieber, Buntingville, Esperanza, Gazelle, Modoc, Ocho, Montague and Weimer soils. Bieber soils have a duripan at a depth of less than 20 inches and are on terraces. Bidwell soils have a clay loam argillic horizon. Buntingville soils have mottles within 20 inches of the surface and have a clay loam argillic horizon. Esperanza soils lack mottles and have a clay argillic horizon. Gazelle soils have a clay argillic horizon and a duripan at depths of 20 to 40 inches. Modoc soils have a clay loam argillic horizon and have a duripan. Montague soils have a petrocalcic horizon below 20 to 40 inches. Ocho soils have a natric horizon and have a duripan at depths less than 20 inches. Weimer soils have mean annual soil temperatures of less than 47 degrees.
DRAINAGE AND PERMEABILITY: Poorly drained; ponded to slow runoff; slow permeability. The soils are flooded for brief to long durations from December to May. During this time the water table fluctuates at depth of 2 to 3 feet. Drained phases have a water table between the depths of 5 and 6 feet.
USE AND VEGETATION: Used for irrigated and nonirrigated wheat and barley and for hay and pasture and as livestock grazing. Vegetation is tuffed hairgrass, alpine timothy, Baltic rush, sedges, bluegrass, and scattered silver sagebrush in the drier locations.
DISTRIBUTION AND EXTENT: Basins and valleys in northeastern California and south-centeral Oregon. The soils are moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Lassen County (Intermountain Soil Survey Area), California, 1920.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - zone from the soil surface to 22 inches (A1, A2, Bss).
Vertical cracks - 1 to 5 cm wide at a depth of 22 inches (A1, A2, Bss).
Intersecting slickensides - zone from 4 to 22 inches (Bss).
Cambic horizon - zone from 22 to 45 inches (Bk1, Bk2).