LOCATION GRANTURK COEstablished Series
TAXONOMIC CLASS: Loamy, isotic Lithic Dystrocryepts
TYPICAL PEDON: Granturk loam, on a southwest facing, simple, 10 percent slope in alpine tundra at an elevation of 12,000 feet. (Colors are for dry soil unless otherwise noted.) When described on September 15, 1987 the soil was moist from 0 to 18 inches.
Oi--0 to 1 inch; slightly decomposed organic material, principally roots, stems, and leaves. (1 to 3 inches thick)
A--1 to 3 inches; weak red (10R 5/2) loam, weak red (10R 4/2) moist; weak fine granular structure; soft, very friable, nonsticky and nonplastic; abundant fine and very fine roots; very strongly acid (pH 5.0); clear smooth boundary. (2 to 7 inches thick)
E--3 to 8 inches; weak red (10R 5/3) loam, weak red (10R 4/2) moist; weak very fine granular structure; soft, very friable, nonsticky and nonplastic; abundant very fine roots; very strongly acid (pH 4.8); clear smooth boundary. (0 to 5 inches thick)
Bw1--8 to 17 inches; pale red (10R 6/4) loam, weak red (10R 4/4) moist; weak fine subangular blocky structure parting to moderate medium granular; soft, very friable, nonsticky and nonplastic; few very fine roots; very strongly acid (pH 4.6); clear smooth boundary. (4 to 16 inches thick)
Bw2--17 to 19 inches; pale red (10R 6/4) very gravelly sandy loam, weak red (10R 4/4) moist; weak fine granular structure; soft, very friable, nonsticky and nonplastic; 35 percent small sandstone gravels; very strongly acid (pH 4.6); abrupt smooth boundary. (0 to 6 inches thick)
R--19 inches; hard red sandstone bedrock.
TYPE LOCATION: San Juan County, Colorado; about 4 miles southwest of Silverton, north of Engineer Mountain; located about 2,100 feet east and 3,000 feet north of the southwest corner of Sec. 19, T. 40 N., R. 8 W.; Engineer Mountain USGS quad.; lat. 37 degrees, 43 minutes, 18 seconds N., and long. 107 degrees, 47 minutes, 39 seconds W., NAD 27
RANGE IN CHARACTERISTICS: (depths given are measured from the mineral soil surface)
Soil moisture regime: udic; dry in some part of the moisture control section for less than 45 cumulative days (typic udic subclass)..
Mean annual soil temperature: 32 to 36 degrees F.
Mean summer soil temperature: 38 to 44 degrees F. with an O horizon.
Depth to lithic contact: 7 to 20 inches
Base saturation: 30 to 50 percent
Lithology of rock fragments: sandstone
Particle-size control section (weighted averages):
Clay content: 20 to 35 percent
Rock fragment content: 0 to 35 percent
A horizon:
Hue: 10R to 5YR
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 3 to 6, dry and moist
Rock fragment content: 0 to 35 percent
Reaction: very strongly acid or strongly acid
Bw1 horizon:
Hue: 10R to 5YR
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 3 to 6, dry and moist
Texture, fine earth fraction: L or CL
Rock fragment content: 0 to 15 percent
Reaction: very strongly acid or strongly acid
Bw2 horizon: (if present)
Hue: 10R to 5YR
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 3 to 6, dry and moist
Texture, fine earth fraction: SL
Rock fragment content: 25 to 50 percent
Reaction: very strongly acid or strongly acid
COMPETING SERIES: This is the
Lostlake series.
The
Liesnoi series may be a competitor when the classification is updated.
Liesnoi: have less than 18 percent clay in the particle-size control section.
Lostlake: have rock fragments derived from granite.
GEOGRAPHIC SETTING:
Parent material: residuum and slope alluvium derived from non-marine redbed sandstone.
Landform: mountain slopes, structural benches, and mesas in alpine areas.
Slopes: 2 to 60 percent
Elevation: 11,500 to 13,000 feet
Mean annual air temperature: 28 to 34 degrees F.
Mean annual precipitation: 35 to 50 inches.
Wettest months: July and August are slightly wetter than other months.
Driest months: May and June receive the least precipitation, however the soils are moist from snowmelt.
Frost-free period: 30 to 40 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Whitecross and Henson series. Both are on mountain slopes.
Whitecross soils are loamy-skeletal, and they are also on ridges and valley floors.
Henson soils are loamy skeletal and very deep, and they are also are in valley fill positions.
DRAINAGE AND PERMEABILITY: Well drained; medium to high runoff; moderate permeability.
USE AND VEGETATION: These soils are used mainly for summer sheep grazing, wildlife habitat, and recreation. Native vegetation consists of alpine bluegrass, tufted hairgrass, scribners wheatgrass, alpine fescue, kobresia, mountain avens, and sedges.
DISTRIBUTION AND EXTENT: Alpine mountain areas of southern Colorado. MLRA 48A. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES ESTABLISHED: San Juan County (Animas-Dolores Soil Survey Area), Colorado, 2002. Series proposed in 1988. The name is taken from a mountain peak near the type location.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon: The zone from 1 to 8 inches. (A and E horizons)
Albic horizon: The zone from 3 to 8 inches (E horizon)
Cambic horizon: The zone from 8 to 19 inches. (Bw1 and Bw2 horizons)
Lithic contact: hard sandstone bedrock at 19 inches.
Particle size control section: The zone from 10 to 19 inches. (Part of the Bw1 and the Bw2 horizons)
Keys to Soil Taxonomy: Classified according to the Eighth Edition, 1998
In some pedons, although color of the Bw horizons meets the criteria of spodic materials, it is presumed this horizon would not meet the organic carbon and oxalate extractable Al and Fe criteria.
The 8/2002 revision changes the mineralogy from mixed to isotic. The isotic class is predicted from the low base status of this soil, the estimated high content of iron and aluminum oxides, and from the cold and moist soil climate.