LOCATION HERM CO+UTEstablished Series
TAXONOMIC CLASS: Fine, smectitic, frigid Typic Argiustolls
TYPICAL PEDON: Herm loam, on a west facing, simple, 5 percent slope in rangeland at an elevation of 8,100 feet. (Colors are for dry soil unless otherwise noted.) Described on October 1,1986.
A--0 to 6 inches; dark grayish brown (10YR 4/2) loam, black (10YR 2/1) moist; moderate medium granular structure; soft, friable, slightly sticky and slightly plastic; common fine and few medium roots; few very fine pores; neutral (pH 6.8); clear smooth boundary. (3 to 10 inches thick)
AB--6 to 13 inches; dark brown (10YR 3/3) clay loam, very dark gray (10YR 3/1) moist; moderate medium subangular blocky structure parting to moderate medium granular; hard, firm, sticky and plastic; common fine and few medium roots; few very fine pores; neutral (pH 6.6); clear smooth boundary. (0 to 8 inches thick)
Bt1--13 to 17 inches; grayish brown (10YR 5/2) clay loam, dark grayish brown (10YR 4/2) moist; strong medium angular and subangular blocky structure; hard, firm, very sticky and very plastic; few distinct clay films on faces of peds; few fine and few medium roots; few very fine pores; neutral (pH 6.6); gradual wavy boundary.
Bt2--17 to 45 inches; brown (10YR 5/3) clay loam, brown (10YR 4/3) moist; strong medium angular and subangular blocky structure; very hard, very firm, very sticky and very plastic; many prominent clay films on faces of peds; common very fine and few fine roots; neutral (pH 6.6); gradual wavy boundary. (combined thickness of the Bt horizons is 20 to 50 inches)
BC--45 to 60 inches; grayish brown (10YR 5/2) clay loam, brown (10YR 4/3) moist; weak medium subangular blocky structure; hard, firm, sticky and plastic; 5 percent gravel, 9 percent cobble; neutral (pH 7.0).
TYPE LOCATION: Montezuma County, Colorado; about 6 miles northeast of Mancos, Colorado, along Forest Service road 566, about 300 feet north of the road; located about 1,100 feet south and 1,700 feet east of the northwest corner of Sec. 7, T. 36 N., R. 12 W.; Rampart Hills USGS quad.; Lat. 37 degrees, 23 minutes, 51 seconds N., and Long. 108 degrees, 13 minutes, 19 seconds W., NAD 27
RANGE IN CHARACTERISTICS:
Soil moisture regime: Ustic
Mean annual soil temperature: 41 to 46 degrees F.
Mean annual summer soil temperature: 50 to 55 degrees F. with an O horizon, and 59 to 63 degrees F. without an O horizon.
Thickness of the mollic epipedon: 10 to 16 inches
Depth to calcium carbonate: if present, 36 to 60 inches
Particle-size control section: 35 to 55 percent clay, 15 to 50 percent silt, 10 to 45 percent sand, and 0 to 30 percent rock fragments, but typically less than 5 percent. They consist of pebbles, cobble and stones mostly derived from sandstone, but have diorite fragments in some pedons.
A horizon:
Hue: 5YR to 10YR
Value: 3 to 5 dry, 2 or 3 moist
Chroma: 1 to 3, dry or moist
Texture: Loam, Clay loam
Rock fragments: 0 to 30 percent, mostly stone and cobble of sandstone and diorite composition
Reaction: slightly acid to slightly alkaline
BA or AB horizon (where present)
Value: 3 to 5 dry, 2 or 3 moist
Chroma: 2 or 3 dry or moist
Texture: silty clay loam, silt loam, or loam
Bt1 horizon:
Hue: 5YR to 10YR
Value: 4 to 6 dry, 2 to 4 moist
Chroma: 2 to 4, dry or moist
Texture: Clay loam, Clay, Silty clay loam
Reaction: slightly acid to slightly alkaline
Bt2 horizon:
Hue: 10YR or 2.5Y
Value: 5 to 7 dry, 4 to 6 moist
Chroma: 3 to 6
Texture: Clay loam, Clay, Silty clay loam
Reaction: slightly acid or neutral
BC horizon: (a Bk or C horizon in some pedons)
Hue: 10YR or 2.5Y
Value: 5 to 7 dry, 4 to 7 moist
Chroma: 2 to 6, dry or moist
Texture: Clay loam, Clay, Silty clay loam
Rock fragments: 0 to 30 percent, sandstone and shale gravel and cobble
Calcium carbonate equivalent: 0 to 5 percent
Reaction: neutral to moderately alkaline
COMPETING SERIES: These are the Absarokee, Acree, Barela, Capillo, Delson, Ekah, Morapos, Moreno, Nortez, Pramiss, Ricot, Tamaneen, Tukuhnik, Work and Zau series.
Absarokee,
Acree,
Ekah,
Morapos,
Ricot,
Tamaneen, and Work: have horizons of calcium carbonate accumulation above a depth of 40 inches.
Absarokee,
Nortez, and
Zau soils have lithic contact at depths of 20 to 40 inches.
Barela, and Capillo: have lithic or paralithic contact at depths of 40 to 60 inches.
Delson, Moreno: have hue of 7.5YR and redder in the lower part of the Bt horizon.
Pramiss: have a paralithic contact between 20 to 40 inches.
Tukuhnik: have a lithic contact at 40 to 60 inches.
GEOGRAPHIC SETTING:
Parent material: slope alluvium derived from shale and sandstone; some pedons are influenced by eolian materials in the upper horizons.
Landform: mountain slopes, hillslopes, structural benches, ridges, mesas, cuestas.
Slopes: 0 to 50 percent
Elevation: 6,800 to 9,500 feet
Mean annual air temperature: 38 to 45 degrees F.
Mean annual precipitation: 14 to 25 inches.
Wettest months: July and August receive slightly more precipitation than other months.
Driest months: May and June receive the least precipitation, however the soils are still moist from snowmelt.
Frost-free period: 75 to 115 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Archuleta, Hesperus, Sanchez, and Valto series.
Archuleta, Sanchez, and Valto soils are shallow over a lithic or paralithic contact. All are on hillslopes and mountain slopes.
Hesperus soils have mollic epipedons more than 16 inches thick and have fine-loamy particle size control sections. They are on mountain slopes and in drainageways.
DRAINAGE AND PERMEABILITY: Well drained; medium runoff; slow permeability.
USE AND VEGETATION: These soils are used for timber production, livestock grazing, and wildlife habitat. Native vegetation consists of, Gambel's oak, snowberry, Arizona fescue, mountain muhly, mountain brome, bluegrass, junegrass, and forbs; with or without an overstory of ponderosa pine.
DISTRIBUTION AND EXTENT: Southwestern Colorado and southeastern Utah. LRR E, MLRA 36, 48A. This series is of moderate extent.
MLRA OFFICE RESPONSIBLE: Lakewood, Colorado
SERIES ESTABLISHED: Paonia Area, Colorado, 1976.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon: The zone from 0 to 13 inches. (A and AB horizons)
Argillic horizon: The zone from 13 to 45 inches. (Bt1 and Bt2 horizons)
Particle-size control section: The upper 20 inches of the argillic horizon, from 13 to 33 inches (Bt1 and part of the Bt2 horizon)
Keys to Soil Taxonomy: Eighth Edition, 1998
The 2/99 revision moved the type location from the La Plata survey area to the Animas-Dolores survey area.