LOCATION HOLDON CAEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive Xeric Haplocryepts
TYPICAL PEDON: Holdon extremely gravelly loamy coarse sand--rangeland. (Colors are for dry soil unless otherwise noted.) The soil surface is covered with 65 percent gravel, 25 percent cobbles, and 3 percent stones.
A--0 to 3 inches; pale brown (10YR 6/3) extremely gravelly loamy coarse sand, brown (10YR 4/3) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine and fine roots; many very fine interstitial pores; 55 percent gravel and 10 percent cobbles; neutral; abrupt wavy boundary. (1 to 3 inches thick)
Bw1--3 to 12 inches; pale brown (10YR 6/3) extremely gravelly coarse sandy loam, brown (10YR 4/3) moist; moderate fine and medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine, fine, medium and coarse and few very coarse roots; common very fine tubular and interstitial and few very fine and fine vesicular pores; 55 percent gravel and 25 percent cobbles; neutral; clear wavy boundary. (4 to 10 inches thick)
Bw2--12 to 23 inches; very pale brown (10YR 7/4) extremely gravelly sandy loam, yellowish brown (10YR 5/4) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; few very fine, fine, medium, coarse, and very coarse roots; many very fine and fine interstitial pores; 55 percent gravel and 25 percent cobbles; neutral; abrupt irregular boundary. (8 to 14 inches thick)
2C--23 to 47 inches; cobbles; few fine and medium roots; many very coarse interstitial pores between fragments; 15 percent gravel and 75 percent cobbles; silt coats on upper surfaces of some fragments; clear wavy boundary.
2R--47 inches; hard, fractured tuff.
TYPE LOCATION: Mono County, California; on the Toiyabe National Forest in the Sweetwater Mountains near the head of Silverado Canyon; approximately 700 feet north and 3,160 feet east of the southwest corner of section 19, T. 7 N., R. 25 E.; USGS Mount Patterson 7.5 minute topographic quadrangle; 38 degrees 26 minutes 44.3 seconds north latitude and 119 degrees 16 minutes 17.6 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 - 35 to 42 degrees F.
Mean summer soil temperature - 46 to 52 degrees F.
Depth to base of cambic horizon - 20 to 40 inches.
Depth to fragmental material - 20 to 40 inches.
Depth to bedrock - 40 to 60 inches to a lithic contact.
Particle-size control section - Clay content: Averages 8 to 15 percent; Rock fragments: Averages 60 to 85 percent in the upper part, and more than 90 percent in the lower part, mainly gravel and cobbles. Lithology of fragments are volcanic rocks such as andesite, tuff, and tuff-breccia and some metavolcanic rock.
A horizon
Hue: 7.5YR through 2.5Y.
Value: 6 or 7 dry, 4 or 5 moist.
Chroma: 2 or 3, dry or moist.
Reaction: Slightly acid or neutral.
Bw horizons
Hue: 7.5YR through 2.5Y.
Value: 6 or 7 dry, 4 or 5 moist.
Chroma: 3 or 4, dry or moist.
Texture: Extremely gravelly coarse sandy loam or extremely gravelly sandy loam.
Clay content: 8 to 15 percent.
Rock fragments: 60 to 85 percent.
Reaction: Slightly acid or neutral.
2C horizon
Hue: 7.5YR through 2.5Y.
Value: 6 or 7 dry, 4 or 5 moist.
Chroma: 3 or 4, dry or moist.
Rock fragments: 90 to 95 percent.
COMPETING SERIES: These are the Ketchum, Longhike (T), Tubbs Hollow (T), and Yankeefork series.
None of these soils have fragmental material in the lower part of the particle-size control section. In addition, Ketchum and Yankeefork soils are very deep; Longhike soils are moderately deep to paralithic contacts; Tubbs Hollow soils are moderately deep to lithic contacts.
GEOGRAPHIC SETTING: Holdon soils are on mountains. They typically occur on backslope positions. They formed in colluvium and residuum derived from volcanic rocks such as andesite, tuff, or tuff-breccia and metavolcanic rocks. Slopes are 30 to 75 percent. Elevations range from 9,500 to 11,500 feet. The climate is subhumid-continental with cold, moist winters and cool, dry summers. The mean annual precipitation is 20 to 30 inches, the mean annual temperature is 33 to 38 degrees F., and the frost-free period is less than 60 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Coldtree, Mountpatterson, and Rolldown series. These soils have argillic horizons.
DRAINAGE AND PERMEABILITY: Well drained; medium surface runoff; moderately rapid permeability (high saturated hydraulic conductivity).
USE AND VEGETATION: Holdon soils are used for rangeland, recreation, watershed, and wildlife habitat. The native vegetation is mainly various alpine forbs and some bluegrass.
DISTRIBUTION AND EXTENT: Eastern California, on the east side of the Sierra Nevada Range. These soils are not extensive with about 2,100 acres of the series mapped to date. MLRA 22A.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES ESTABLISHED: Mono County (Toiyabe National Forest Area), California, 2006.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the soil surface to 7 inches (A horizon and part of the Bw1 horizon).
Cambic horizon - The zone from 3 to 23 inches (Bw1 and Bw2 horizons).
Lithic contact - The boundary at 47 inches to underlying hard bedrock (2R layer).
Particle-size control section - The zone from 10 to 40 inches (Bw2 horizon and parts of the Bw1 and 2C horizons).
The revision of December 2006 updated the taxonomic class from Xeric Eutrocryepts based on the tenth edition of the Keys to Soil Taxonomy, 2006.