LOCATION WELLTOMAS CAEstablished Series
TAXONOMIC CLASS: Ashy-skeletal, glassy, frigid Lithic Argixerolls
TYPICAL PEDON: Welltomas very gravelly ashy loam--rangeland. (Colors are for dry soil unless otherwise noted). The soil surface is partly covered by 45 percent gravel, 5 percent cobbles and 5 percent stones.
A--0 to 2 inches; brown (10YR 5/3) crushed very gravelly ashy loam, dark brown (10YR 3/3) crushed moist; weak fine subangular blocky structure; soft, very friable, nonsticky, nonplastic; common fine roots and many very fine roots; common very fine interstitial and tubular pores; 50 percent pebbles; neutral, (pH 6.8); clear smooth boundary. (1 to 5 inches thick)
Bt--2 to 7 inches; brown (7.5YR 5/2) crushed very gravelly ashy clay loam, dark brown (7.5YR 3/2) crushed moist; moderate fine and medium subangular blocky structure; slightly hard, friable, moderately sticky, moderately plastic; common very fine and fine roots; common very fine interstitial and tubular pores; 20 percent distinct clay films on all faces of peds and 20 percent distinct clay films on surfaces along pores; 50 percent pebbles; neutral, (pH 6.9); abrupt wavy boundary. (4 to 9 inches thick)
R--7 inches; unweathered andesitic tuff-breccia.
TYPE LOCATION: Modoc County, California; on the Modoc National Forest in the Warner Mountains; 800 feet north and 1,800 feet east of the southwest corner of section 3, T 42N., R 15E. Cedarville USGS 7.5 minute topographic quadrangle; 41 degrees 31 minutes 3 seconds north latitude and 120 degrees 13 minutes 40 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 - 7 to 14 inches.
Depth to bedrock - 7 to 14 inches to hard bedrock. The lithic materials below the contact are pyroclastic andesitic tuff or tuff-breccia.
Reaction - Slightly acid or neutral.
Particle-size control section - Clay content: Averages 18 to 27 percent, (field estimates).
Rock fragments: 35 to 60 percent, mainly gravel and cobbles.
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 clay loam, or ashy sandy clay loam.
Clay content: 18 to 30 percent.
Rock fragments: 35 to 60 percent.
Structure: Moderate or strong, fine to coarse subangular blocky.
Organic matter content: 1 to 2 percent.
COMPETING SERIES: These are the Anaud, Domehill, Farepeak, Fingerridge, Granquin, Hardnut, Schoolmarm, Skidbrackle, and Starflyer soils. The Anaud, Domehill, Farepeak, Granquin, Hardnut, Schoolmarm, and Starflyer soils have an aridic moisture regime. Farepeak, Schollmarm and Starflyer have 27 to 35 percent clay in the control section. Hardnut and Skidbrackle soils have bedrock within 14 to 20 inches and have greater than 60 percent rock fragments in the control section. Fingerridge soils have less than 18 percent clay in the control section.
GEOGRAPHIC SETTING: Welltomas soils are on mountains. They formed in volcanic ash and colluvium over residuum derived from andesitic tuff and tuff-breccia. Slopes are 4 to 50 percent. Elevations range from 4,900 to 7,020 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 Crazybird and Warnermount series. Crazybird soils have paralithic material within 14 to 20 inches. Warnermount soils have bedrock at 40 to 60 inches.
DRAINAGE AND PERMEABILITY: Well drained; medium or high surface runoff; moderately rapid permeability.
USE AND VEGETATION: Welltomas soils are used for watershed, wildlife habitat, and livestock grazing. The vegetation consists of bluebunch wheatgrass, needlegrass, low 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:
Diagnostic horizons and features recognized in this pedon include:
Mollic epipedon - The zone from the mineral soil surface to 7 inches (A and the Bt horizons).
Vitrandic intergrade feature -- High volcanic glass content in the .02 to 2mm fraction from the mineral soil surface to 7 inches (A and the Bt horizons).
Argillic horizon - The zone from 2 to 7 inches (Bt horizon).
Lithic contact - The boundary at 7 inches to underlying hard bedrock (R layer).
Particle-size control section - The zone from the surface to 7 inches (A and Bt horizons).