LOCATION GRAYHEAD COEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive Pachic Haplocryolls
TYPICAL PEDON: Grayhead sandy loam, on a southeast facing 26 percent mountain slope under seral aspen at an elevation of 10,020 feet. (colors are for dry soil unless otherwise noted.)
A1--0 to 8 inches; very dark gray (10YR 3/1) sandy loam, black (10YR 2/1) moist; weak fine subangular blocky structure parting to weak fine granular; soft, very friable, nonsticky and slightly plastic; neutral (pH 6.8); gradual smooth boundary.
A2--8 to 16 inches; dark grayish brown (10YR 4/2) sandy loam, very dark brown (10YR 2/2) moist; weak very fine and fine subangular blocky structure; soft, very friable, nonsticky and slightly plastic; neutral (pH 6.8); gradual smooth boundary. (combined thickness of the A horizons is 14 to 36 inches)
Bw--16 to 43 inches; grayish brown (10YR 5/2) sandy loam, very dark grayish brown (10YR 3/2) moist; weak fine and medium subangular blocky structure; soft, very friable, nonsticky and slightly plastic; 1 inch of clay loam lamella; 10 percent gravel, trace cobbles; neutral (pH 6.6); gradual smooth boundary. (20 to 30 inches thick)
Cr1--43 to 57 inches; very dark gray (5YR 3/1) weathered granodiorite grus; few pockets of light yellowish brown (10YR 6/4) gravelly loamy sand, dark yellowish brown (10YR 4/4) moist; fine rock structure; soft, very friable, nonsticky and nonplastic; 20 percent gravel; slightly acid (pH 6.4); gradual smooth boundary. (0 to 20 inches thick)
Cr2--57 inches; weathered granodiorite bedrock.
TYPE LOCATION: Gunnison County, Colorado; about 7 miles east of Doyleville, Colorado; located about 700 feet south and 2200 feet east of the northwest corner of Section 1, T. 48 N., R. 4 E.; USGS Sargents topographic quadrangle; latitude 38 degrees, 27 minutes, 19 seconds north and longitude 106 degrees, 28 minutes, 46 seconds west, NAD 1927.
RANGE IN CHARACTERISTICS:
Soil moisture: The soil moisture control section (smcs) is affected by precipitation that falls evenly throughout the year with the exception of a significant increase in July and August. The smcs is driest during the fall. The smcs is too dry for Udic and is considered to have an Ustic soil moisture regime.
Mean annual soil temperature: 38 to 40 degrees F.
Particle-size control section: 10 to 18 percent clay, 0 to 20 percent rock fragments
Depth to paralithic contact: 40 to 60 inches to weathered granodiorite
Thickness of mollic epipedon: 16 to 44 inches.
A horizons:
Hue: 7.5YR or 10YR
Value: 3 to 5 dry, 2 or 3 moist
Chroma: 1 or 2 dry or moist
Reaction: slightly acid (pH 6.1) to neutral (pH 7.3)
Rock fragments: granite, granodiorite, granodiorite gneiss, or quartz monzonite. 0 to 10 percent total rock fragments; 0 to 10 percent gravel.
Bw horizon:
Hue: 7.5YR or 10YR
Value: 4 or 5 dry, 3 or 4 moist
Chroma: 2 or 3 dry or moist
Texture: sandy loam, fine sandy loam, gravelly sandy loam, gravelly fine sandy loam
Reaction: slightly acid (pH 6.1) to neutral (pH 7.3)
Rock fragments: granite, granodiorite, granodiorite gneiss, or quartz monzonite. 0 to 20 percent total rock fragments; 0 to 20 percent gravel, 0 to 5 percent cobbles.
Some pedons do not have lamella in the Bw horizon.
COMPETING SERIES: These are the
Coutis,
Gardners Fork,
Hailman,
Naz,
Razorba, and
Skyway series.
Coutis, Gardners Fork, Naz, Razorba: do not have paralithic contacts within 60 inches
Hailman: has udic soil moisture regime
Skyway: lithic contact with sandstone between 20 and 40 inches
GEOGRAPHIC SETTING:
Parent material: slope alluvium and colluvium over residuum from granite, granodiorite, granodiorite gneiss, or quartz monzonite
Landform: mountain slopes
Slopes: 15 to 40 percent
Elevation: 9,600 to 10,400 feet
Mean annual temperature: 36 to 38 degrees F.
Mean annual precipitation: 20 to 22 inches
Frost-free period: 55 to 60 days
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Snowdon and Storm soils. The Snowdon soils are on shoulders and have a lithic contact at less than 20 inches. Storm soils are on backslopes and have more than 35 percent rock fragments in the particle-size control section.
DRAINAGE AND PERMEABILITY: well drained; high to very high runoff; moderate permeability.
USE AND VEGETATION: This soil is used for wood products. Native vegetation is currently seral aspen, nodding bromegrass, elk sedge, and Rocky Mountain Douglas fir. Potential native vegetation is Rocky Mountain Douglas fir with an understory of elk sedge, common juniper, kinnikinnick, and myrtle whortleberry. It is in the Rocky Mountain Douglas Fir Woodland Site, Forest Cover Type 210.
DISTRIBUTION AND EXTENT: Western Colorado in LRR E and MLRA 48A. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Cochetopa Soil Survey Area, Gunnison National Forest, Gunnison County, Colorado, 1999. The name comes from Gray Head mountain and Gray Head topographic quadrangle.
REMARKS: Diagnostic horizons and features recognized in this pedon.
Particle-size control section: the zone from 10 to 40 inches. (A2 and Bw horizons)
Mollic epipedon: the zone from 0 to 43 inches. (A and Bw horizons)
Paralithic contact: the contact with granodiorite grus at 43 inches (Cr layer)
Taxonomic version: Eighth Edition, 1998.