LOCATION DISMALSWAMP CAEstablished Series
TAXONOMIC CLASS: Ashy, glassy Aquandic Cryaquolls
TYPICAL PEDON: Dismalswamp ashy loam--rangeland. (Colors are for dry soil unless otherwise noted).
A1--0 to 3 inches; dark grayish brown (10YR 4/2) ashy loam, very dark brown (10YR 2/2) moist; moderate fine subangular blocky structure; soft, very friable, slightly sticky, slightly plastic; common very fine tubular and many very fine interstitial pores; neutral, (pH 6.8); clear smooth boundary. (2 to 8 inches thick)
A2--3 to 8 inches; dark grayish brown (10YR 4/2) ashy 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 interstitial and tubular pores; slightly acid, (pH 6.5); clear wavy boundary. (4 to 10 inches thick)
A3--8 to 13 inches; gray (10YR 5/1) ashy loam, very dark gray (10YR 3/1) moist; moderate medium subangular blocky structure; slightly hard, very friable, moderately sticky, slightly plastic; common very fine interstitial and tubular pores; 30 percent distinct dark yellowish brown (10YR 3/4) moist, irregular redox concentrations; 5 percent pebbles; slightly acid, (pH 6.5); clear wavy boundary. (4 to 10 inches thick)
A4--13 to 22 inches; gray (10YR 5/1) gravelly ashy loam, very dark gray (10YR 3/1) moist; moderate medium subangular blocky structure; slightly hard, very friable, moderately sticky, moderately plastic; common very fine interstitial and tubular pores; 30 percent distinct dark yellowish brown (10YR 3/4) moist, redox concentrations; 15 percent pebbles; slightly acid, (pH 6.2); clear wavy boundary. (0 to 15 inches thick)
Cg1--22 to 31 inches; light brownish gray (2.5Y 6/2) gravelly ashy loam, grayish brown (2.5Y 5/2) moist; massive; soft, very friable, slightly sticky, nonplastic; few very fine and fine roots; many very fine interstitial and common very fine tubular pores; 40 percent distinct dark yellowish brown (10YR 3/4) moist, redox concentrations; 25 percent pebbles; slightly acid, (pH 6.1); clear wavy boundary. (6 to 12 inches thick)
Cg2--31 to 60 inches; light brownish gray (2.5Y 6/2) very gravelly ashy loam, grayish brown (2.5Y 5/2) moist; massive; soft, very friable, slightly sticky, slightly plastic; few very fine and fine roots; many very fine interstitial pores; 40 percent distinct dark yellowish brown (10YR 3/4) moist, redox concentrations; 5 percent cobbles and 50 percent pebbles; moderately acid, (pH 5.8).
TYPE LOCATION: Modoc County, California; on the Modoc National Forest in the Warner Mountains; no PLSS survey available; Mt. Bidwell USGS 7.5 minute topographic quadrangle; 41 degrees 59 minutes 0.8 seconds north latitude and 120 degrees 8 minutes 42.5 seconds west longitude, NAD27.
RANGE IN CHARACTERISTICS:
Soil moisture - Usually saturated in some part of the moisture control section during winter, spring, and early summer, usually dry in all parts during summer and fall; seasonal periods of aquic moisture regime from November through June during saturation with ground water and anaerobic conditions.
Mean annual soil temperature - 41 to 45 degrees F.
Mean summer soil temperature - 47 to 55 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 - 20 to 30 inches.
Profile reaction - Moderately acid or slightly acid.
Particle-size control section - Clay content: Averages 18 to 27 percent, (field estimates).
Rock fragments: average 15 to 35 percent, mainly gravel or 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: 2 to 4 percent.
Redoximorphic features: Redox concentrations occur as masses of iron or manganese accumulation in the matrix or as coats on rock fragments.
Cg1 horizon -
Texture: Ashy loam or ashy sandy loam.
Clay content: Average18 to 27 percent.
Rock fragments: Average 15 to 35 percent.
Redoximorphic features: Redox concentrations occur as masses of iron or manganese accumulation in the matrix or as coats on rock fragments.
Organic matter content: 1 to 3 percent.
Cg2 horizon -
Texture: Ashy loam or ashy sandy loam.
Clay content: Average18 to 27 percent.
Rock fragments: Average 35 to 60 percent.
Redoximorphic features: Redox concentrations occur as masses of iron or manganese accumulation in the matrix or as coats on rock fragments.
Organic matter content: 1 to 2 percent.
COMPETING SERIES: This is the Liart series. Liart soils do not have layers with more than 35 percent rock fragments within 20 to 40 inches, have less than 50 percent volcanic glass and have mean summer soil temperatures less than 47 degrees.
GEOGRAPHIC SETTING: Dismalswamp soils are in intermountain valleys on floodplains, stream terraces and valley sides. They formed in volcanic ash and local alluvium derived from volcanic rocks. Slopes are 0 to 8 percent. Elevations range from 6,080 to 8,200 feet. The climate is subhumid with cold, moist winters and warm, dry summers. The mean annual precipitation is 20 to 50 inches, most of which comes as snow. The mean annual temperature is 38 to 44 degrees F. The frost-free period is 30 to 60 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Gurlidawg, Paynepeak and Pyropatti series. All these soils have bedrock within 60 inches and lack saturation within the upper part of the profile.
DRAINAGE AND PERMEABILITY: Poorly drained and very poorly drained; high or very high surface runoff; moderate permeability. Endosaturation is present with an apparent seasonal high water table between the soil surface and 20 inches (very shallow free water occurrence classes) from November through June. Cumulative annual duration classes are common or persistent. Some areas of these soils are susceptible to rare flooding for brief periods between December and June.
USE AND VEGETATION: Dismalswamp soils are used for watershed, wildlife habitat, and limited livestock grazing. The vegetation consists of willows, sedges, forbs and tufted hairgrass.
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 from a nearby landmark.
Diagnostic horizons and features recognized in this pedon include:
Mollic epipedon - The zone from the soil surface to 22 inches (A horizons).
Aquandic intergrade feature -- High volcanic glass content in the .02 to 2mm fraction from the mineral soil surface to 60 inches (A and the Cg horizons).
Particle-size control section - The zone from 10 to 30 inches (part of A3, A4 and part of Cg horizons).