LOCATION HAWKRIDGE CAEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Lithic Argixerolls
TYPICAL PEDON: Hawkridge extremely gravelly coarse sandy loam--rangeland. (Colors are for dry soil unless otherwise noted.) The soil surface is covered with 50 percent gravel, 5 percent cobbles, and 3 percent stones.
A1--0 to 1 inch; grayish brown (10YR 5/2) extremely gravelly coarse sandy loam, very dark grayish brown (10YR 3/2) moist; weak medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; few very fine roots; many very fine interstitial pores; 70 percent gravel and 5 percent cobbles; slightly acid; abrupt wavy boundary. (1 to 4 inches thick)
A2--1 to 7 inches; brown (10YR 5/3) very gravelly sandy loam, very dark grayish brown (10YR 3/2) moist; weak fine and medium subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; many very fine roots; common very fine interstitial and tubular pores; 45 percent gravel and 5 percent cobbles; slightly acid; clear wavy boundary. (0 to 6 inches thick)
Bt--7 to 14 inches; brown (10YR 5/3) very gravelly sandy clay loam, dark brown (10YR 3/3) moist; moderate fine and medium subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; common very fine and fine roots; common very fine interstitial and tubular pores; common faint clay bridges on sand grains; 45 percent gravel and 5 percent cobbles; slightly acid; abrupt wavy boundary. (3 to 7 inches thick)
R--14 inches; hard tuff-breccia.
TYPE LOCATION: Alpine County, California; on the Toiyabe National Forest about 1 mile southeast of Hawkins Peak; approximately 1,825 feet north and 1,175 feet east of the southwest corner of section 11, T. 10 N., R. 19 E.; USGS Markleeville 7.5 minute topographic quadrangle; 38 degrees 43 minutes 30.1 seconds north latitude and 119 degrees 51 minutes 49.9 seconds west longitude, NAD27.
RANGE IN CHARACTERISTICS:
Soil moisture - Usually moist in the moisture control section during fall, winter, and spring; dry from mid-July through September for 60 to 80 consecutive days in the four months following the summer solstice; Typic xeric moisture regime.
Mean annual soil temperature - 42 to 45 degrees F.
Mean summer soil temperature - 59 to 62 degrees F.
Mollic epipedon thickness - 7 to 14 inches, includes the Bt horizon.
Depth to bedrock - 7 to 14 inches to a lithic contact.
Sodium fluoride pH - 8.5 to 9.0.
Particle-size control section - Clay content: Averages 14 to 20 percent; Rock fragments: Averages 35 to 60 percent, mainly gravel. Lithology of fragments are volcanic rocks such as tuff, tuff-breccia, and andesite.
A horizons - Value: 4 or 5 dry, 2 or 3 moist.
Chroma: 2 or 3, dry or moist.
Organic matter content: 2 to 4 percent.
Reaction: Slightly acid or neutral.
Bt horizon - Hue: 10YR or 7.5YR.
Chroma: 3 or 4 dry, 3 moist.
Texture: Very gravelly sandy clay loam, extremely gravelly coarse sandy loam, or very gravelly loam.
Clay content: 18 to 27 percent.
Rock fragments: 50 to 80 percent.
Organic matter content: 1 to 3 percent.
Reaction: Slightly acid or neutral.
COMPETING SERIES: These are the Bellenmine, Celeridge, Cleavage, Cleavmor, Cropper, Gabica, Gaciba, Genoa, Gerdog, Gidwin, Grosschat, Hutchley, Loope, Mascamp, Melling, Pernog, Pernty, Rozara, Shalcleav, Shalper, Slatter (T), Tractuff, and Tweener series.
Bellenmine, Cleavage, Cleavmor, Cropper, Gaciba, Grosschat, Mascamp, Pernty, Shalper, Slatter, Tractuff, and Tweener soils have an aridic moisture regime. Celeridge, Gabica, Gidwin, and Loope soils have lithic contacts at depths of 14 to 20 inches. Genoa soils are dominated by cobbles in the particle-size control section and have rock fragments that are granitic rocks. Gerdog soils have mean summer soil temperature of 62 to 66 degrees F. Hutchley soils have subhorizons of the argillic horizon with 28 to 35 percent clay. Melling soils are dry for 45 to 60 consecutive days in the four months following the summer solstice. Pernog soils are dominated by stones and have more than 27 percent clay in some part of the particle-size control section. Rozara soils are dominated by fine gravel in the particle-size control section and have rock fragments that are granitic rocks. Shalcleav soils are dominated by channers and flagstones.
GEOGRAPHIC SETTING: Hawkridge soils are on mountains. They typically occur on shoulder positions. These soils formed in residuum and colluvium derived from tuff, tuff-breccia, and andesite. Slopes are 4 to 30 percent. Elevations range from 8,000 to 10,000 feet. The climate is subhumid-continental with cold, moist winters and warm, dry summers. The mean annual precipitation is 20 to 50 inches, the mean annual temperature is 36 to 39 degrees F., and the frost-free period is 30 to 60 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Hawkinspeak and Lithnip soils. Hawkinspeak soils are moderately deep to lithic contacts and have thick mollic epipedons. Lithnip soils have ochric epipedons and do not have argillic horizons.
DRAINAGE AND PERMEABILITY: Well drained; very high surface runoff; moderate permeability (moderately high or high saturated hydraulic conductivity).
USE AND VEGETATION: Hawkridge soils are used for rangeland, recreation, watershed, and wildlife habitat. The native vegetation is mainly low sagebrush, bluegrass ssp., Eriogonum ssp., and Haplopappus ssp.
DISTRIBUTION AND EXTENT: Eastern California, on the east side of the Sierra Nevada Range. These soils are not extensive with about 7,400 acres of the series mapped to date. MLRA 22A.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Alpine County (Toiyabe National Forest Area), California, 2006.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 14 inches (A1, A2, and Bt horizons).
Argillic horizon - The zone from 7 to 14 inches (Bt horizon).
Lithic contact - The boundary at 14 inches to underlying hard bedrock (R layer).
Particle-size control section - The zone from the soil surface to 14 inches (A1, A2, and Bt horizons).
The revision of October 2003 updated the taxonomic class from Loamy-skeletal, isotic Lithic Argicryolls. Local soil temperature data indicates this soil has mean summer soil temperatures in the range of the frigid temperature regime. The isotic mineralogy class was based solely on the field determined values for sodium fluoride pH. Laboratory data on 15 bar water to clay ratio does not exist to verify the isotic mineralogy class.