LOCATION LONGCREEK CA+ID NV OREstablished Series
TAXONOMIC CLASS: Clayey-skeletal, smectitic, mesic Lithic Argixerolls
TYPICAL PEDON: Longcreek very cobbly loam--on a north to northwest-facing slope of 18 percent under mountain big sagebrush, cheatgrass, bluebunch wheatgrass, and Thurber's needlegrass at 4,600 feet elevation--rangeland. (Colors are for dry soil unless otherwise noted. When described on June 15, 1979, the soil was dry to 7 inches and slightly moist from 7 to 18 inches.)
A--0 to 3 inches; dark grayish brown (10YR 4/2) very cobbly loam, very dark brown (10YR 2/2) moist; moderate fine and medium granular structure; slightly hard, very friable, moderately sticky and moderately plastic; common very fine and fine roots; many very fine and fine tubular and interstitial pores; 3 percent stones; 25 percent cobbles and 20 percent gravel; neutral (pH 7.0); clear smooth boundary. (2 to 8 inches thick)
BAt--3 to 7 inches; brown (7.5YR 4/2) very cobbly clay loam, dark brown (7.5YR 3/2) moist; moderate medium angular blocky structure; hard, friable, moderately sticky and moderately plastic; common very fine and fine and few medium roots; many very fine and fine tubular pores; few faint clay films bridging mineral grains; 30 percent cobbles and 15 percent gravel; neutral (pH 7.0); clear wavy boundary. (0 to 6 inches thick)
Bt1--7 to 12 inches; brown (7.5YR 4/2) very cobbly clay, dark brown (7.5YR 3/2) moist; strong fine and medium angular blocky structure; very hard, friable, very sticky and very plastic; common very fine, few fine and medium roots; common very fine and fine tubular pores; 25 percent cobbles and 15 percent gravel; common pressure cutans on faces of peds; neutral (pH 7.0); gradual wavy boundary.
Bt2--12 to 18 inches; light brown (7.5YR 6/4) very cobbly clay, brown (7.5YR 4/4) moist; strong medium and coarse angular blocky structure; very hard, friable, very sticky and very plastic; common very fine and few fine and medium roots, mostly along or on peds; common very fine and fine and few medium tubular pores; 25 percent cobbles and 15 percent gravel; few faint clay films on rock fragments; common pressure cutans on faces of peds; neutral (pH 7.0); abrupt irregular boundary. (Combined thickness of the Bt horizons is 7 to 14 inches)
R--18 inches; hard fractured andesite with some material between cracks and many clay film coatings on fractures.
TYPE LOCATION: Lassen County, California; north of the Skedaddle Mountains about 0.5 mile southwest of Horsecamp Reservoir found at a site about 0.75 mile north of Brubeck Spring and 0.75 mile west of the road on a northeast-facing slope; about 750 feet north and 500 feet west of the southeast corner of section 28, T. 30 N., R. 16 E.; USGS Little Mud Flat 7.5 minute topographic quadrangle; 40 degrees 25 minutes 37 seconds north latitude and 120 degrees 10 minutes 23 seconds west longitude, NAD27.
RANGE IN CHARACTERISTICS:
Soil moisture - These soils are dry in all parts of the moisture control section from early June through mid November (167 days). The soil temperature exceeds 41 degrees F. from early April through early December (243 days) and exceeds 47 degrees F. from early May through mid November; Aridic moisture regime that borders on xeric.
Mean annual soil temperature - 47 to 53 degrees F.
Mollic epipedon thickness - 7 to 14 inches; includes the BAt horizon (when present) and the Bt1 horizon.
Depth to base of argillic horizon - 10 to 20 inches.
Depth to bedrock - 10 to 20 inches to a lithic contact.
Particle-size control section - Clay content: Averages 35 to 50 percent; Rock fragments: 35 to 55 percent, mainly cobbles. Lithology of fragments are volcanic rocks such as basalt and andesite.
Other features - Rock fragments on the surface range from 30 to 50 percent, mostly cobbles and stones.
A horizon - Dry color: 10YR 4/2, 4/3, 5/2, 5/3, 5/4; 7.5YR 5/2 or 4/2.
Moist color: 10YR 2/2, 3/2 or 7.5YR 3/2.
Texture: Very cobbly loam, very stony loam extremely stony loam, gravelly loam, or cobbly loam.
Rock fragments: 40 to 60 percent.
Structure: In the upper 2 or 3 inches is moderate or strong medium or fine granular or weak thin to thick platy. The lower part of the A horizon is moderate or strong, fine or medium, angular or subangular, blocky structure.
Organic matter content: 1 to 4 percent.
Reaction: Slightly acid or neutral.
Bt horizons - Dry color: 10YR 4/3, 5/3, 5/4, 6/3; 7.5YR 4/2, 4/4, 5/2, 5/4, 6/2 or 6/4.
Moist color: 10YR 3/2, 3/3, 4/3; 7.5YR 3/2, 4/2, 4/4; 5YR 3/2 or 3/3.
Texture: Very cobbly clay, very cobbly silty clay, very cobbly clay loam, very stony clay, or very gravelly clay loam.
Clay content: 35 to 50 percent.
Rock fragments: 35 to 55 percent, mainly cobbles.
Structure: Strong fine or moderate medium angular or subangular blocky in the upper part and strong medium and coarse angular blocky or is weak or strong fine to coarse prismatic parting to strong or moderate fine to coarse angular blocky in the lower part.
Organic matter content: 0.5 to 2 percent.
Reaction: Neutral or slightly alkaline.
COMPETING SERIES: These are the Camaspatch, Flatron, Gwinly, Laufer, Loomer, Lorella, Pioche, Radec, Ruckles, Vantage, and Waterbury series.
Camaspatch, Flatron, Gwinly, Laufer, Lorella, Radec, and Waterbury soils have a xeric moisture regime. Loomer soils have 60 to 80 percent rock fragments in the particle-size control section. Pioche soils have rock fragments that are quartzite in the particle-size control section and are more moist in spring and summer months due to summer convection storms. Ruckles soils are dominated by stones and average 50 to 60 percent clay in the particle-size control section. Vantage soils have a subhorizon of the argillic with secondary silica coats and are dry in all parts for less than 140 days.
GEOGRAPHIC SETTING: Longcreek soils are on lava plateaus, structural benches, hills, and mountains. These soils formed in residuum and colluvium derived from volcanic rocks such as basalt, andesite, and tuff. Slopes are 2 to 75 percent. Elevation ranges from 3,600 to 5,600 feet and up to 6,600 feet on south-facing aspects. The climate is semiarid with cool, moist winters and warm, dry summers. The mean annual precipitation is 9 to 16 inches. The mean annual temperature is 44 to 50 degrees F., the mean January temperature is about 28 degrees F., and the mean July temperature is about 64 degrees F. The frost-free period is 50 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Brubeck, Devada, Gerlach, Glean, Horsecamp, and Shinnpeak soils. Brubeck and Horsecamp soils are fine, have ochric epipedons and cambic horizons, and have cracks that open and close each year. Devada soils are clayey. Gerlach soils are fine, very deep, and have cracks that open and close each year. Glean soils are loamy-skeletal, deep to lithic contacts, and have thick mollic epipedons. Shinnpeak soils are loamy-skeletal, shallow to indurated duripans, and have ochric epipedons and argillic horizons.
DRAINAGE AND PERMEABILITY: Well drained; very high surface runoff; slow permeability.
USE AND VEGETATION: Longcreek soils are used for rangeland and wildlife habitat. The vegetation is mountain big sagebrush, basin big sagebrush, Wyoming big sagebrush, bluebunch wheatgrass, Thurber's needlegrass, Sandberg's bluegrass, and bottlebrush squirreltail.
DISTRIBUTION AND EXTENT: Northeastern California, southwestern Idaho, south-central Oregon, and western Nevada. These soils are moderately extensive. The series concept and main acreage is in MLRA 23, while other acreage occurs in MLRAs 10, 21, 25, and 26.
MLRA OFFICE RESPONSIBLE: Reno, Nevada.
SERIES ESTABLISHED: Owyhee County Area, Idaho, 1992. The series was proposed from the Susanville Area Soil Survey, California in 1980. The type location is currently in this survey area.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 12 inches (A, BAt, and Bt1 horizons).
Argillic horizon - The zone from 7 to 18 inches (Bt1 and Bt2 horizons).
Lithic contact - The boundary at 18 inches to underlying hard, unweathered bedrock (R layer).
Particle-size control section - The zone from 7 to 18 inches (Bt1 and Bt2 horizons).