LOCATION MONCHEGO COEstablished Series
TAXONOMIC CLASS: Fine-loamy over sandy or sandy-skeletal, mixed, superactive Ustic Haplocryolls
TYPICAL PEDON: Monchego sandy loam, on a northwest facing 3 percent slope in rangeland at an elevation of 9,330 feet. (colors are for dry soil unless otherwise noted)
A1--0 to 5 inches; dark grayish brown (10YR 4/2) sandy loam, very dark grayish brown (10YR 3/2) moist; weak very fine and fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; neutral (pH 7.0); clear smooth boundary.
A2--5 to 13 inches; brown (7.5YR 5/2) sandy clay loam, dark brown (7.5YR 3/2) moist; weak fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; 5 percent gravel; neutral (pH 7.0); abrupt smooth boundary. (combined thickness of the A horizons is 7 to 15 inches)
2C1--13 to 18 inches; yellowish brown (10YR 5/4) extremely gravelly loamy sand, dark yellowish brown (10YR 3/4) moist; massive; loose, nonsticky and nonplastic; 55 percent gravel, 5 percent cobbles; slightly alkaline (pH 7.4); abrupt smooth boundary.
2C2--18 to 29 inches; grayish brown (10YR 5/2) very gravelly sand, dark grayish brown (10YR 4/2) moist; single grained; loose, nonsticky and nonplastic; 45 percent gravel; slightly alkaline (pH 7.6); abrupt smooth boundary.
2C3--29 to 46 inches; light brownish gray (10YR 6/2) gravelly sand, dark grayish brown (10YR 4/2) moist; single grained; loose, nonsticky and nonplastic; 25 percent gravel; slightly alkaline (pH 7.6); abrupt smooth boundary.
2C4--46 to 66 inches; pale brown (10YR 6/3) extremely gravelly sand, brown (10YR 4/3) moist; single grained; loose, nonsticky and nonplastic; 50 percent gravel, 10 percent cobbles; slightly alkaline (pH 7.6). (combined thickness of the 2C horizons is 45 to 60 inches)
TYPE LOCATION: Saguache County, Colorado; about 24 miles south of Parlin, Colorado; within an unsectionized area of Gunnison National Forest, estimated to be in Section 19, T. 45 N., R. 3 E.; USGS Cochetopa Park topographic quadrangle; latitude 38 degrees, 09 minutes, 04 seconds north and longitude 106 degrees, 41 minutes, 31 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 bordering on Aridic soil moisture regime.
Mean annual soil temperature: 43 to 45 degrees F.
Thickness of mollic epipedon: 7 to 15 inches
Depth to lithologic discontinuity: 7 to 15 inches to sandy-skeletal materials
Particle-size control section: 3 to 14 percent clay, 25 to 65 percent rock fragments.
A horizons:
Hue: 7.5YR or 10YR
Value: 4 or 5 dry, 2 or 3 moist
Chroma: 2 or 3 dry or moist
Texture: sandy loam or sandy clay loam
Reaction: neutral (pH 6.6) to (pH 7.3)
Rock fragments: andesite, rhyolite, breccia, or tuff. 0 to 20 percent total rock fragments; 0 to 20 percent gravel, 0 to 5 percent cobbles.
2C horizons:
Hue: 7.5YR to 2.5Y
Value: 5 to 7 dry, 3 to 5 moist
Chroma: 2 to 4 dry or moist
Texture: extremely gravelly loamy sand, very gravelly sand, gravelly sand, extremely gravelly sand
Reaction: neutral (pH 6.6) to slightly alkaline (pH 7.8)
Rock fragments: andesite, rhyolite, breccia, or tuff. 25 to 65 percent total rock fragments; 20 to 60 percent gravel, 0 to 15 percent cobbles.
COMPETING SERIES: This is the
Maxville series.
Maxville: greater than 18 percent clay in the particle-size control section and secondary accumulations of calcium carbonate
GEOGRAPHIC SETTING:
Parent material: slope alluvium and outwash from andesite, rhyolite, breccia, or tuff
Landform: outwash fans and outwash terraces
Slopes: 2 to 25 percent
Elevation: 9,000 to 9,500 feet
Mean annual temperature: 40 to 42 degrees F.
Mean annual precipitation: 16 to 18 inches
Frost-free period: 65 to 70 days
GEOGRAPHICALLY ASSOCIATED SOILS: This is the Lagarita soil. Lagarita soils are on alluvial fans and have an argillic horizon.
DRAINAGE AND PERMEABILITY: well drained; medium to very high runoff; moderate permeability.
USE AND VEGETATION: This soil is used for rangeland. Potential native vegetation is slimstem muhly, fringed sagebrush, blue grama, and sheep fescue. It is in the Mountain Outwash Range Site, RS 311.
DISTRIBUTION AND EXTENT: Western Colorado in LRR E and MLRA 48B. 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 comes from Monchego Creek.
REMARKS: Diagnostic horizons and features recognized in this pedon.
Particle-size control section: the zone from 10 to 40 inches. (A2, 2C1, 2C2, 2C3 horizons)
Mollic epipedon: the zone from 0 to 13 inches. (A horizons)
Lithologic discontinuity: At the upper boundary of the sandy-skeletal material at 13 inches. (2C horizons)
This soil potentially has a xeric soil moisture regime.
Taxonomic version: Eighth Edition, 1998.