LOCATION HAWKINSPEAK CAEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive Pachic Argicryolls
TYPICAL PEDON: Hawkinspeak very gravelly sandy loam--rangeland. (Colors are for dry soil unless otherwise noted.) The soil surface is covered with 45 percent gravel, 5 percent cobbles, 3 percent stones, and 1 percent boulders.
A1--0 to 3 inches; grayish brown (10YR 5/2) 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 nonplastic; common very fine roots; common very fine interstitial and tubular pores; 30 percent gravel, 5 percent cobbles, and 5 percent stones; slightly acid; clear wavy boundary. (2 to 5 inches thick)
A2--3 to 9 inches; brown (10YR 5/3) very gravelly sandy loam, dark brown (10YR 3/3) moist; weak fine and medium subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; common very fine and common fine roots; common very fine interstitial and common very fine tubular pores; 45 percent gravel and 5 percent cobbles; slightly acid; clear wavy boundary. (4 to 7 inches thick)
Bt1--9 to 15 inches; brown (10YR 5/3) very gravelly sandy clay loam, dark brown (10YR 3/3) moist; moderate fine and medium subangular blocky structure; slightly hard, very friable, moderately sticky and slightly plastic; common very fine, common fine, and common medium roots; common very fine interstitial and tubular pores; few faint clay bridges on sand grains; 45 percent gravel and 5 percent cobbles; slightly acid; clear wavy boundary. (4 to 15 inches thick)
Bt2--15 to 33 inches; brown (10YR 5/3) very gravelly sandy clay loam, dark brown (10YR 3/3) moist; moderate fine and medium subangular blocky structure; slightly hard, very friable, moderately sticky and slightly plastic; common very fine, common fine, and common medium roots; common very fine interstitial and common tubular pores; common faint clay bridges on sand grains; 50 percent gravel and 5 percent cobbles; slightly acid; abrupt irregular boundary. (7 to 18 inches)
R--33 inches; fractured, hard tuff.
TYPE LOCATION: Alpine County, California; on the Toiyabe National Forest southwest of Hawkins Peak; approximately 675 feet north and 2,450 feet west of the southeast corner of section 3, T. 10 N., R. 19 E.; USGS Carson Pass 7.5 minute topographic quadrangle; 38 degrees 44 minutes 3.8 seconds north latitude and 119 degrees 52 minutes 31.5 seconds west longitude, NAD27.
RANGE IN CHARACTERISTICS:
Soil moisture - Usually moist in the moisture control section during late 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 46 degrees F.
Mean summer soil temperature - 50 to 54 degrees F.
Mollic epipedon thickness - 20 to 40 inches, includes the Bt1 horizon or both the Bt1 and Bt2 horizon in some pedons.
Depth to bedrock - 20 to 40 inches to a lithic contact.
Sodium fluoride pH - 8.5 to 9.0.
Particle-size control section - Clay content: Averages 18 to 27 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 5 percent.
Reaction: Slightly acid or neutral.
Bt horizons - Hue: 10YR or 7.5YR.
Value: 5 or 6 dry, 3 or 4 moist.
Chroma: 3 or 4, dry or moist.
Texture: Very gravelly sandy clay loam, very gravelly loam, or very gravelly sandy loam.
Clay content: 18 to 27 percent.
Rock fragments: 35 to 60 percent.
Reaction: Slightly acid or neutral.
COMPETING SERIES: These are the Angelwhine, Aspetill, Badwater, Bickmore, Bluebell, Booneville, Buena Vista, Dab, Dailybasin (T), Delhew, Keman, Littlemud (T), Lostcannon, Monibasin, Parkalley (T), Parkay, Redbird, Rutherford, Sweetmount, and Woodhurst series.
Angelwhine, Aspetill, Badwater, Booneville, Dab, Delhew, Keman, Lostcannon, Monibasin, Parkalley, Parkay, and Redbird soils are very deep. Bickmore soils have Btk horizons with 15 to 40 percent calcium carbonate equivalent. Bluebell soils are dominated by stones in the particle-size control section. Buena Vista soils are dominated by stones in the particle-size control section and have horizons with identifiable secondary carbonates. Dailybasin soils have an ustic moisture regime. Littlemud soils have mollic epipedons that do not include the argillic horizon and have rock fragments which are quartzite or rhyolite. Sweetmount soils are deep to paralithic contacts and have subhorizons of the argillic horizon with 27 to 50 percent clay. Rutherford soils have mean summer soil temperature of 55 to 59 degrees F. Woodhurst soils have an ustic moisture regime and mean summer soil temperature of 55 to 59 degrees F.
GEOGRAPHIC SETTING: Hawkinspeak soils are on mountains. They typically occur on backslope positions. These soils formed in colluvium and residuum derived from tuff, tuff-breccia, and andesite. Slopes are 15 to 50 percent. Elevations range from 8,000 to 10,000 feet. The climate is subhumid-continental with cold, moist winters and cool, 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 Hawkridge and Lithnip soils. These soils are shallow to lithic contacts.
DRAINAGE AND PERMEABILITY: Well drained; very high surface runoff; moderate permeability (moderately high or high saturated hydraulic conductivity).
USE AND VEGETATION: Hawkinspeak soils are used for rangeland, recreation, watershed, and wildlife habitat. The native vegetation is mainly mountain big sagebrush, antelope bitterbrush, mountain brome, and Letterman's needlegrass.
DISTRIBUTION AND EXTENT: Eastern California, on the east side of the Sierra Nevada Range. These soils are moderately extensive. 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 33 inches (A1, A2, Bt1, and Bt2 horizons).
Argillic horizon - The zone from 9 to 33 inches (Bt1 and Bt2 horizons).
Lithic contact - The boundary at 33 inches to underlying hard bedrock (R layer).
Particle-size control section - The zone from 9 to 29 inches (Bt1 horizon and part of the Bt2 horizon).
The revision of October 2003 updated the taxonomic class from Loamy-skeletal, isotic Pachic Argicryolls. 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.