LOCATION ALTURAS CAEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Typic Natrixerolls
TYPICAL PEDON: Alturas silt loam, dryland pasture (Colors are for dry soil unless noted).
A11--0 to 2 inches; gray (10YR 5/1) silt loam, very dark gray (10YR 3/1) moist; weak medium and thick platy structure; hard, friable, sticky, slightly plastic; common very fine and few fine roots; common very fine tubular pores; violently effervescent, with disseminated lime; moderately alkaline (pH 8.0); clear smooth boundary. (0 to 2 inches thick)
A12--2 to 10 inches; gray (10YR 5/1) loam, very dark gray (10YR 3/1) moist; weak fine and medium subangular blocky structure; hard, friable, sticky, slightly plastic; common very fine and few fine roots; few very fine tubular pores; bleached silica grains; violently effervescent, with disseminated lime; moderately alkaline (pH 8.0); clear wavy boundary. (4 to 7 inches thick)
A13--10 to 17 inches; gray (10YR 6/1) light clay loam, very dark gray (10YR 3/1) moist; weak medium and coarse angular blocky structure; weak medium and coarse angular blocky structure; hard, very friable, sticky, slightly plastic; common very fine and few fine roots, common very fine tubular pores; bleached silica grains; violently effervescent, with disseminated lime; moderately alkaline (pH 8.0); clear wavy boundary. (4 to 7 inches thick)
B21t--17 to 22 inches; dark gray (10YR 4/1) heavy clay loam, very dark gray (10YR 3/1) moist; moderate very fine and fine prismatic parting to fine and medium angular blocky structure; very hard, very friable, sticky, plastic; few very fine and fine roots; common very fine and fine tabular and few very fine interstitial pores; many thin clay films in pores; upper part of horizon is degrading; strongly effervescent with disseminated line; moderately alkaline (pH 8.0); clear smooth boundary. (4 to 10 inches thick)
B22tca--22 to 30 inches; grayish brown (10YR 5/2) heavy clay loam, dark grayish brown (10YR 4/2) moist; moderate fine and medium prismatic parting to fine and medium angular structure; hard, very friable, sticky, plastic; few very fine and fine roots; few very fine tubular pores; many thin clay films on peds and in pores; violently effervescent, lime segregated in irregular soft bodies; moderately alkaline (pH 8.0); clear smooth boundary. (6 to 14 inches thick)
B3tca--30 to 42 inches; dark brown (10YR 4/3) heavy clay loam, dark brown (10YR 3/3) moist; massive; hard, very friable, sticky, plastic; few very fine roots; few very fine tubular and interstitial pores; many moderately thick clay films line pores and as bridges; violently effervescent, lime segregated in fine rounded soft effervescent, lime segregated in fine rounded soft bodies; moderately alkaline (pH 8.0); clear irregular boundary. (6 to 24 inches thick)
IIC1--42 to 50 inches; grayish brown (10YR 5/2) gravelly heavy loam, dark brown (10YR 3/3) moist; common fine prominent yellowish brown (10YR 5/6) mottles; massive; slightly hard, very friable, slightly sticky, slightly plastic; few very fine roots; common very fine interstitial and few very fine tabular pores; many thin colloidal stained on mineral grains; 15 percent rounded gravel by volume; very weakly cemented; slightly effervescent, lime segregated in fine rounded soft bodies; moderately alkaline (pH 8.0); clear smooth boundary. (6 to 8 inches thick)
IIIC2--50 to 58 inches; light brownish gray (2.5Y 6/2) gravelly sandy loam, very dark grayish brown (2.5Y 3/2) moist; few fine prominent dark brown (10YR 3/3) moist mottles; massive; slightly hard, very friable, slightly sticky, nonplastic; no roots; many very fine interstitial and few very fine tubular pores; common thin colloidal stains on mineral grains; 30 percent rounded gravel by volume; weekly cemented; slightly effervescent, lime segregated in fine rounded soft bodies; moderately alkaline (pH 8.0)
TYPICAL LOCATION: Modoc County, California; about on 5 miles south of the town of Davis Creek; 1.4 miles west on County Road 209 from Hwy 395 to railroad tracks and 0.2 miles west on dirt road, 102 feet south of an east-west fence; NW1/4 NE1/4 sec., T. 44 N., R. 13 E.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is about 49 to 54 degrees F. The soil temperature is warmer than 41 degrees F from March 25 through November 30. The soil between depths of 4 to 12 inches is usually dry in all parts from July 10 until October 15 and is moist in some or all parts from December 22 to April 22. The soil is effervescent throughout, with the greatest accumulation in the lower B horizon. Depth to a water table or mottles is more than 30 inches.
The A horizon is gray or grayish brown in the upper 10 inches and light gray, gray,light brownish gray, or grayish brown in the lower part, in 10YR hue. It is loam, silt loam, or dark grayish brown, very dark gray, very dark brown, or black, in 10YR hue. It is loam, silt loam, or silty clay loam and has platy or subangular blocky structure or is massive and slightly hard. Electrical conductivity is highest in the A horizon with 2 to 8 mmhos/cm.
The B horizon is brown grayish brown, dark grayish brown, gray, or dark gray, in 10YR hue. Moist colors are brown and dark gray to black 10YR 4/3, 4/2, 4/1, 3/3, 2/2, 2/1. The B horizon is heavy clay loam, silty clay loam, or clay and averages 35 to45 percent clay in the upper 20 inches. It has moderate or strong prismatic structure parting to angular blocky structure, and is massive in the lower part. This horizon is moderately or strongly alkaline and is assumed to have more than 15 percent exchangeable sodium in some part. In some pedons a Blt horizon is present or the B3t horizon is absent.
The C horizon is pale brown, light brownish gray, grayish brown, or brown dry and dark brown, very dark grayish brown, or very dark brown moist in 10YR or 2.5YR hue. It is stratified and is loamy coarse sand, loamy fine sand, sandy loam, or loam and has up to about 20 percent durinodes. Cementation and the durinodes occur at depth of about 40 to 50 inches.
COMPETING SERIES: These are the Calneva, Couch, McKay, Rumbo, Standish, Trenton and Wahtum series. Calneva, Couch, Rumbo, and Standish soils have ochric epipedons and aridic moisture regimes. McKay soils have fine-silty control sections and are noneffervescent in the A horizon. Trenton soils have mixed mineralogy and 7.5 YR hue in the B2t horizon and 5YR hue in the C horizon. Wahtum soils have clayey over loamy control sections and have durinodes or weakly cemented horizons above depth of 40 inches.
GEOGRAPHIC SETTING: Alturas soils are in nearly level basin edges and low terraces where salts have wicked up from lower areas and are at elevation of 4,100 to 4,800 feet. They formed in stratified sediments from basic igneous and pyroclastic rocks. The climate is cool semiarid mesothermal with warm dry summers and cold moist winters. Mean annual precipitation is 8 to 15 inches. Snowfall is 20 to 49 inches. Average January temperature is 27 to 30 degrees F; average July temperature is 67 to 70 degrees F, mean annual temperature is 46 to 49 degrees F. The freeze-free season is 80 to 130 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Rumbo soils and the Balman, Barnard, Buntingville, Modoc, Pineal and Pit soils. Balman soils have fine-loamy control sections, have calcic horizons and lack argillic horizons. Barnard soils have fine-loamy B2t horizons and have aridic moisture regime. Buntingville soils have fine-loamy B2t and have duripans at depths of less than 20 inches. Pit soils are clayey throughout, with many slickensides.
DRAINAGE AND PERMEABILITY: Moderately well and somewhat poorly drained; slow runoff; slow permeability.
USE OF VEGETATION: Irrigated and dryland pasture, range, and small areas of grain crops. Vegetation is saltgrass, alkali meadow grass, squirrel tail, rabbitbrush, and cheatgrass.
DISTRIBUTION AND EXTENT: Basins and valleys of the Modoc Plateau in northeastern California and possibly south-central Oregon. The soils are inextensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Modoc County (Alturas Area), California, 1974.
REMARKS: The Alturas soils would have been mapped as Solonetz soils.
ADDITIONAL DATA: Riverside Laboratory pedon S73 Calif 25-4; not published to date.
Last revised by the state on 5/74.