LOCATION COCHEDOME COEstablished Series
TAXONOMIC CLASS: Clayey-skeletal, smectitic Ustollic Haplocryalfs
TYPICAL PEDON: Cochedome gravelly sandy loam, on a east facing 11 percent structural bench slope, under a ponderosa pine woodland at an elevation of 9,570 feet. (colors are for dry soil unless otherwise noted.)
Oi--0 to 1 inch; mat of slightly decomposed needles, twigs, and leaves.(0 to 2 inches thick)
A--1 to 6 inches; dark grayish brown (10YR 4/2) gravelly sandy loam, very dark brown (10YR 2/2) moist; weak fine and medium granular structure; soft, very friable, nonsticky and nonplastic; 20 percent gravel; neutral (pH 7.0); clear smooth boundary.(5 to 9 inches thick)
E--6 to 10 inches; pinkish gray (7.5YR 6/2) very gravelly sandy clay loam, dark brown (7.5YR 3/2) moist; weak fine and medium granular structure; slightly hard, friable, slightly sticky and slightly plastic; 35 percent gravel; neutral (pH 6.8); gradual smooth boundary.(2 to 5 inches thick)
Bt1--10 to 22 inches; light brown (7.5YR 6/4) very gravelly clay, brown (7.5YR 4/4) moist; strong medium and coarse prismatic structure; very hard, very firm, very sticky and very plastic; common distinct clay films on faces of peds; 45 percent gravel, 10 percent cobbles; neutral (pH 6.6); gradual smooth boundary.
Bt2--22 to 38 inches; light brown (7.5YR 6/4) extremely cobbly clay, brown (7.5YR 4/4) moist; strong coarse angular blocky structure; very hard, very firm, very sticky and very plastic; many prominent clay films on faces of peds; 40 percent gravel, 20 percent cobbles, 5 percent stones; neutral (pH 6.6); abrupt smooth boundary.(combined thickness of the Bt horizons is 16 to 30 inches)
R--38 inches; hard fractured andesite bedrock.
TYPE LOCATION: Saguache County, Colorado; about 19 miles south of Parlin, Colorado; within an unsectionized area of Gunnison National Forest, estimated to be in Section 31, T. 46 N., R. 3 E.; USGS Cochetopa Park topographic quadrangle; latitude 38 degrees, 12 minutes, 08 seconds north and longitude 106 degrees, 41 minutes, 31 seconds west, NAD 1927.
RANGE IN CHARACTERISTICS: Depths in this section are measured from the top of the mineral soil surface.
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 42 degrees F.
Thickness of mollic colors (after mixing): 6 to 9 inches
Depth to argillic horizon: 6 to 11 inches
Depth to lithic contact: 20 to 40 inches to andesite
Particle-size control section: 35 to 55 percent clay, 35 to 70 percent rock fragments.
A horizon:
Hue: 7.5YR or 10YR
Value: 4 or 5 dry, 2 or 3 moist
Chroma: 2 or 3 dry or moist
Reaction: slightly acid (pH 6.1) to neutral (pH 7.3)
Rock fragments: andesite, rhyolite, breccia, or tuff. 5 to 45 percent total rock fragments; 5 to 45 percent gravel, 0 to 15 percent cobbles, 0 to 5 percent stones.
E (albic) horizon:
Hue: 5YR to 10YR
Value: 6 or 7 dry, 3 to 5 moist
Chroma: 2 or 3 dry or moist
Texture: very gravelly sandy clay loam, very gravelly loam, gravelly sandy clay loam, gravelly loam, gravelly sandy loam
Clay content: 22 to 30 percent.
Reaction: slightly acid (pH 6.1) to neutral (pH 7.3)
Rock fragments: andesite, rhyolite, breccia, or tuff. 20 to 50 percent total rock fragments; 20 to 50 percent gravel, 0 to 15 percent cobbles, 0 to 10 percent stones.
Bt horizons:
Hue: 5YR or 7.5YR
Value: 5 to 7 dry, 3 to 5 moist
Chroma: 4 or 5 dry or moist
Texture: very gravelly clay, extremely cobbly clay, extremely gravelly clay, extremely gravelly clay loam, very gravelly clay loam, extremely cobbly clay loam
Clay content: 35 to 50 percent.
Reaction: slightly acid (pH 6.1) to neutral (pH 7.3)
Rock fragments: andesite, rhyolite, breccia, or tuff. 35 to 70 percent total rock fragments; 35 to 70 percent gravel, 0 to 30 percent cobbles, 0 to 15 percent stones.
COMPETING SERIES: This is the
Recklor series.
Recklor: do not have a lithic contact with 60 inches
GEOGRAPHIC SETTING:
Parent material: slope alluvium and colluvium over residuum from andesite, rhyolite, breccia, or tuff
Landform: mountain slopes and structural benches
Slopes: 5 to 65 percent
Elevation: 9,100 to 10,200 feet
Mean annual temperature: 36 to 40 degrees F.
Mean annual precipitation: 18 to 22 inches, with June, July, and August being the wettest months
Frost-free period: 55 to 65 days
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Quander and Snowdon soils. The Quander soils are on backslopes and footslopes and have less than 35 percent clay in the particle-size control section. The Snowdon soils are on backslopes and summits and have a lithic contact above 20 inches.
DRAINAGE AND PERMEABILITY: well drained; medium to very high runoff; slow permeability.
USE AND VEGETATION: This soil is used for livestock grazing and wood products. Potential native vegetation is ponderosa pine with an understory of Arizona fescue, mountain muhly, Parry oatgrass, and western wheatgrass. It is in the Interior Ponderosa Pine Woodland Site, Forest Cover Type 237.
DISTRIBUTION AND EXTENT: Southwest 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, Saguache County, Colorado, 1999. The name is coined from Cochetopa Dome.
REMARKS: Diagnostic horizons and features recognized in this pedon.
Particle-size control section: the zone from 10 to 30 inches. (Bt horizons)
Ochric epipedon: the zone from 1 to 10 inches. (A and E horizon)
Albic horizon: the zone from 6 to 10 inches. (E horizon)
Argillic horizon: the zone from 10 to 38 inches. (Bt horizons)
Lithic contact: the contact with andesite bedrock at 38 inches (R layer)
This pedon does not have an abrupt textural change.
Taxonomic version: Eighth Edition, 1998.