LOCATION DECOROCK COEstablished Series
TAXONOMIC CLASS: Clayey-skeletal, smectitic, mesic Typic Argigypsids
TYPICAL PEDON: Decorock very gravelly clay loam, on a northwest facing, 45 percent slope in rangeland at an elevation of 5,040 feet. (Colors are for dry soil unless otherwise noted.) The surface is covered by 40 percent gravel, 25 percent cobbles, and 5 percent stones (rounded igneous).
A--0 to 5 inches; yellowish brown (10YR 5/4) very gravelly clay loam, light olive brown (2.5Y 5/3) moist; moderate medium granular structure; soft, very friable, very sticky and very plastic; many very fine roots throughout; 12 percent calcium carbonate equivalent; 38 percent clay; 30 percent gravel, 10 percent cobbles, and 1 percent stones; violently effervescent; slightly alkaline (pH 7.8); clear smooth boundary.
BA--5 to 10 inches; light yellowish brown (2.5Y 6/4) gravelly clay loam, light olive brown (2.5Y 5/4) moist; moderate medium subangular blocky structure parting to moderate medium granular; slightly hard, friable, very sticky and very plastic; many very fine roots throughout; common very fine dendritic tubular pores; few fine irregular masses of gypsum; 13 percent calcium carbonate equivalent; 37 percent clay; 20 percent gravel, 5 percent cobbles, and 1 percent stones; violently effervescent; moderately alkaline (pH 8.0); gradual smooth boundary.
By1--10 to 15 inches; light yellowish brown (2.5Y 6/4) gravelly clay, light olive brown (2.5Y 5/4) moist; moderate medium subangular blocky structure; hard, very firm, very sticky and very plastic; common very fine roots throughout; few fine and common very fine dendritic tubular pores; few fine irregular masses of gypsum; 11 percent calcium carbonate equivalent; 2 percent gypsum; EC .4 mmhos/cm; 42 percent clay; 15 percent gravel, 10 percent cobbles, and 1 percent stones; violently effervescent; moderately alkaline (pH 8.0); gradual smooth boundary.
By2--15 to 26 inches; light yellowish brown (2.5Y 6/4) gravelly clay, light olive brown (2.5Y 5/4) moist; moderate medium and coarse subangular blocky structure; hard, very firm, very sticky and very plastic; few very fine roots throughout; many very fine dendritic tubular pores; few distinct clay films on rock fragments and on surfaces along pores; common fine irregular masses of gypsum; calcium carbonate coatings on bottom of rock fragments; 16 percent calcium carbonate equivalent, 1 percent visible calcium carbonates; 2 percent gypsum; EC .7 mmhos/cm; 44 percent clay; 15 percent gravel, 10 percent cobbles, and 1 percent stones; violently effervescent; moderately alkaline (pH 8.0); clear smooth boundary.
Bty--26 to 58 inches; light yellowish brown (2.5Y 6/4) extremely cobbly clay loam, light olive brown (2.5Y 5/4) moist; moderate medium and coarse subangular blocky structure; hard, very firm, very sticky and very plastic; few very fine roots throughout; few very fine dendritic tubular pores; few distinct clay films on rock fragments and on surfaces along pores; calcium carbonate and gypsum pendants on bottom of rock fragments; many medium irregular nests of gypsum; 12 percent calcium carbonate equivalent, 1 percent visible calcium carbonates; 7 percent gypsum; EC 8 mmhos/cm; 55 percent clay; 35 percent gravel, 30 percent cobbles, and 1 percent stones; violently effervescent; moderately alkaline (pH 8.0); clear smooth boundary.
2Cr--58 to 78 inches; soft Mancos Shale.
TYPE LOCATION: Montezuma County, Colorado; about 2 miles southwest of intersection of highways 41 and 164; Sentinel Peak SW, Colorado USGS quad; lat. 37 degrees 00 minutes 11.18 seconds N. and long. 108 degrees 58 minutes 44.83 seconds W., NAD 27.
RANGE IN CHARACTERISTICS:
Soil moisture regime: Typic aridic
Mean annual soil temperature: 54 to 58 degrees F
Depth to paralithic contact: 40 to 60 inches to soft Mancos Shale
Depth to gypsum accumulations: 5 to 15 inches
Depth to gypsic horizon: 15 to 30 inches
Particle-size control section (weighted average):
Clay content: 40 to 60 percent
Rock fragments: 35 to 60 percent rounded igneous gravel, cobbles, and stones
A horizon: (Thickness 2 - 6 inches)
Hue: 2.5Y or 10YR
Value: 5 dry, 4 or 5 moist
Chroma: 3 or 4
Texture: clay loam
Clay content: 27 to 40 percent
Rock fragments: 35 to 60 percent rounded igneous gravel, cobbles, and stones
Calcium carbonate equivalent: 10 to 15 percent
EC (mmhos/cm): 0 to 2
Gypsum: 1 to 5 percent
SAR: 0 to 1
Reaction: slightly alkaline
By horizon: (Thickness 10 - 30 inches)
Hue: 2.5Y
Value: 6 dry, 5 moist
Chroma: 4
Texture: clay loam, clay, or silty clay loam
Clay content: 35 to 45 percent
Rock fragments: 15 to 35 percent rounded igneous gravel, cobbles, and stones
Calcium carbonate equivalent: 10 to 20 percent
EC (mmhos/cm): 0 to 2
Gypsum: 1 to 5 percent
SAR: 0 to 1
Reaction: moderately alkaline
Bty horizon: (Thickness 20 - 40 inches)
Hue: 2.5Y
Value: 6 dry, 5 moist
Chroma: 4
Texture: clay or clay loam
Clay content: 35 to 60 percent
Rock fragments: 60 to 80 percent rounded igneous gravel and cobbles
Calcium carbonate equivalent: 10 to 15 percent
EC (mmhos/cm): 4 to 8
Gypsum: 5 to 10 percent
SAR: 0 to 1
Reaction: moderately alkaline
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING:
Parent material: igneous alluvium over residuum derived from Mancos shale
Landform: risers of strath terraces and remnant terraces
Slopes: 20 to 50 percent
Elevation: 4,700to 5,700 feet
Mean annual temperature: 52 to 56 degrees F
Mean annual precipitation: 7 to 10 inches
Precipitation pattern: uniform with slight dip in May and June and slight increase in July and August
Frost-free period: 135 to 160 days
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Salamander, Persayo, Greycap, and Gypsey series. The Salamander soils are very deep and are on treads of strath terraces and remnant terraces. The Persayo soils are shallow, the Gypsey soils are moderately deep, and both series are on pediments. Greycap soils are very shallow and are on structural benches.
DRAINAGE AND PERMEABILITY: Well drained, very high runoff, slow permeability.
USE AND VEGETATION: The Decorock soils are used for rangeland. Native vegetation is galleta, Indian ricegrass, Gardners saltbush, and shadscale.
DISTRIBUTION AND EXTENT: Montezuma County, Colorado, Ute Mountain Ute Reservation. MLRA 35. This series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona.
SERIES ESTABLISHED: Montezuma County, Colorado, Ute Mountain Area, Colorado and New Mexico, 2005.
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Series control section: The zone from 0 to 59 inches.
Particle-size control section: The zone from 26 to 46 inches. (Bty horizon)
Ochric epipedon: The zone from 0 to 7 inches. (A and BA horizons)
Argillic horizon: The zone from 26 to 58 inches. (Bty horizon)
Gypsic horizon: The zone from 15 to 30 inches. (Bty horizon)
Paralithic contact: The contact with soft Mancos Shale at 58 inches. (2Cr horizon)
This soil does not have a calcic horizon because no horizon has 5 percent or more visible carbonates, and no horizon has a calcium carbonate equivalent that is 5 percent or more higher than that of an underlying horizon.
ADDITIONAL DATA: A HACH kit was used to determine gypsum concentrations. A portable EC meter was used for electrical conductivity. Calcium carbonate equivalence was determined using a field volume calcimeter.
Classified according to Keys to Soil Taxonomy Ninth Edition, 2003