LOCATION SESDAH CAEstablished Series
TAXONOMIC CLASS: Ashy, glassy, frigid, shallow Vitrandic Argixerolls
TYPICAL PEDON: Sesdah gravelly ashy loam--rangeland. (Colors are for dry soil unless otherwise noted).
A1--0 to 2 inches; dark grayish brown (10YR 4/2), gravelly ashy loam, very dark brown (10YR 2/2), moist; moderate fine granular structure; soft, very friable, slightly sticky, slightly plastic; many very fine roots; many very fine interstitial and few very fine tubular pores; 15 percent pebbles; neutral, (pH 6.8); clear wavy boundary. (1 to 6 inches thick)
A2--2 to 5 inches; brown (10YR 4/3), gravelly ashy loam, very dark brown (10YR 2/2), moist; moderate fine and medium subangular blocky structure; slightly hard, very friable, slightly sticky, slightly plastic; many very fine and fine roots and few medium roots; few very fine tubular and many very fine interstitial pores; 15 percent pebbles; neutral, (pH 6.9); clear wavy boundary. (0 to 6 inches thick)
Bt1--5 to 10 inches; brown (10YR 4/3), gravelly ashy loam, very dark brown (10YR 2/2), moist; moderate fine and medium subangular blocky structure; slightly hard, very friable, moderately sticky, moderately plastic; common very fine to medium roots; common very fine interstitial and tubular pores; 30 percent faint clay films on surfaces along pores and 30 percent faint clay films on all faces of peds; 10 percent paragravel and 20 percent hard pebbles; neutral, (pH 6.9); clear wavy boundary. (4 to 10 inches thick)
Bt2--10 to 16 inches; brown (10YR 4/3), very gravelly ashy sandy clay loam, very dark brown (10YR 2/2), moist; moderate fine and medium subangular blocky structure; slightly hard, very friable, slightly sticky, slightly plastic; common very fine and fine roots and few medium roots; common very fine interstitial and tubular pores; 30 percent faint clay films on all faces of peds and 30 percent faint clay films on surfaces along pores; 5 percent cobbles, 30 percent paragravel and 35 percent hard pebbles; neutral, (pH 6.9); clear irregular boundary. (0 to 8 inches thick)
Cr--16 to 20 inches; weathered tuff-breccia.
TYPE LOCATION: Modoc County, California; on the Modoc National Forest in the Warner Mountains; 350 feet south and 1,700 feet east of the northwest corner of section 31, T 42N., R 16E.; Warren Peak USGS 7.5 minute topographic quadrangle; 41 degrees 28 minutes 13.9 seconds north latitude and 120 degrees 11 minutes 32.1 seconds west longitude, NAD27.
RANGE IN CHARACTERISTICS:
Soil moisture - These soils are usually moist in winter, spring, and early summer, dry later in summer and fall; xeric soil moisture regime.
Mean annual soil temperature - 43 to 47 degrees F.
Oxalate extractable Al + 1/2 Fe: 0.2 to 0.4 percent.
Volcanic glass content - 50 to 80 percent in the coarse silt through fine sand fractions.
Mollic epipedon thickness - 14 to 20 inches.
Depth to bedrock - 14 to 20 inches to weathered bedrock. The paralithic materials below the contact are pyroclastic tuff-breccia.
Profile reaction - Slightly acid or neutral.
Particle-size control section - Clay content: Averages 18 to 27 percent, (field estimates).
Rock fragments: Average 15 to 35 percent, mainly gravel.
A horizons - Hue: 10YR or 7.5YR.
Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 2 or 3, dry or moist.
Organic matter content: 1 to 2 percent.
Bt horizon - Hue: 10YR or 7.5YR.
Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 2 or 3, dry or moist.
Texture: Ashy loam, ashy sandy loam or ashy sandy clay loam.
Clay content: 18 to 27 percent.
Rock fragments: Average 15 to 35 percent, dominantly pebbles. Paragravel generally increases with depth in the profile.
Structure: Moderate or strong, fine to coarse subangular blocky.
Organic matter content: 1 to 2 percent.
COMPETING SERIES: There are currently no other series in this family.
GEOGRAPHIC SETTING: Sesdah soils are on mountains. They formed in volcanic ash and colluvium over residuum derived from glassy tuff-breccia. Slopes are 30 to 75 percent. Elevations range from 4,690 to 7,160 feet. The climate is subhumid with cold, moist winters and warm, dry summers. The mean annual precipitation is 16 to 26 inches, most of which comes as snow. The mean annual temperature is 41 to 45 degrees F. The frost-free period is 50 to 80 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Hartner, Lyonman and Welltomas series. Hartner soils are less than 10 inches to bedrock and do not have a mollic epipedon or an argillic horizon. Lyonman soils have bedrock within 20 to 40 inches. Welltomas soils have lithic material within 7 to 14 inches.
DRAINAGE AND PERMEABILITY: Well drained; medium or high surface runoff; moderate permeability.
USE AND VEGETATION: Sesdah soils are used for watershed, wildlife habitat, and livestock grazing. The vegetation consists of bluebunch wheatgrass, Idaho fescue, mountain big sagebrush, and antelope bitterbrush.
DISTRIBUTION AND EXTENT: Northeastern California. These soils are not extensive. MLRA 21.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California.
SERIES ESTABLISHED: Surprise Valley-Home Camp Area, California and Nevada, 2005.
REMARKS: The name is coined.
Diagnostic horizons and features recognized in this pedon include:
Mollic epipedon - The zone from the mineral soil surface to 16 inches (A1, A2, Bt1 and the Bt2 horizons).
Vitrandic intergrade feature - High volcanic glass content in the .02 to 2mm fraction from the mineral soil surface to 16 inches (A1, A2 and the Bt horizons).
Argillic horizon - The zone from 5 to 16 inches (Bt horizons).
Paralithic contact - The boundary at 16 inches to underlying soft weathered bedrock (Cr layer).
Particle-size control section - The zone from 5 to 16 inches (Bt horizons).