LOCATION MOUNTPOOR COEstablished Series
TAXONOMIC CLASS: Clayey-skeletal, smectitic Typic Palecryalfs
TYPICAL PEDON: Mountpoor loam, on a east facing, 47 percent mountain slope, under spruce-fir woodland at an elevation of 9,620 feet. (colors are for dry soil unless otherwise noted. When described on October 9, 1985, the soil was moist in some parts.)
Oi--0 to 3 inches; mat of slightly decomposed needles, twigs, and leaves (0 to 3 inches thick)
E--3 to 20 inches; light yellowish brown (10YR 6/4) loam, dark yellowish brown (10YR 3/4) moist; moderate fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; 10 percent gravel; slightly acid (pH 6.4); clear smooth boundary. (12 to 22 inches thick)
E/B--20 to 31 inches; (E portion - 60 percent) light brownish gray (10YR 6/2) very cobbly loam, dark grayish brown (10YR 4/2) moist; weak fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; and (B portion - 40 percent) light yellowish brown (10YR 6/4) very cobbly clay loam, dark yellowish brown (10YR 3/4) moist; moderate medium subangular blocky structure; slightly hard, friable, sticky and plastic; common faint clay films on faces of peds; this horizon consists of intermixed blotches of loam E material and clay loam B material; 15 percent gravel, 30 percent cobbles; slightly acid (pH 6.4); gradual wavy boundary. (6 to 16 inches thick)
B/E--31 to 39 inches; (B portion -70 percent) light yellowish brown (10YR 6/4) very cobbly clay, olive brown (2.5Y 4/4) moist; moderate fine and medium angular blocky structure; hard, friable, sticky and plastic; common distinct clay films on faces of peds; (E portion - 30 percent) light brownish gray (10YR 6/2) very cobbly clay loam, dark grayish brown (10YR 4/2) moist; weak fine and medium angular blocky structure; hard, friable, sticky and plastic; this horizon consists of intermixed blotches of clay B material and clay loam E material; 25 percent gravel, 30 percent cobbles; neutral (pH 6.6); gradual smooth boundary. (0 to 12 inches thick)
Bt--39 to 69 inches; light yellowish brown (10YR 6/4) extremely cobbly clay, olive brown (2.5Y 4/4) moist; strong fine and medium angular blocky structure; very hard, firm, very sticky and very plastic; many distinct clay films on faces of peds; 30 percent gravel, 30 percent cobbles; neutral (pH 6.6). (20 to 40 inches thick)
TYPE LOCATION: San Miguel County, Colorado; about 8 miles southwest of Sawpit, Colorado; located about 300 feet north and 1900 feet east of the southwest corner of Section 15, T. 42 N., R. 11 W.; USGS Little Cone topographic quadrangle; Latitude: 37 degrees, 53 minutes, 50 seconds north; Longitude: 108 degrees, 04 minutes, 06 seconds west; NAD 1927.
RANGE IN CHARACTERISTICS:
Depths in this section are measured from the top of the mineral soil surface.
Soil moisture regime: udic; dry for less than 30 days in summer.
Mean annual soil temperature: 37 to 43 degrees F.
Depth to top of argillic horizon: 24 to 40 inches.
Particle-size control section: 35 to 50 percent clay, 35 to 80 percent rock fragments.
E horizon:
Hue: 10YR or 2.5Y
Value: 6 or 7 dry, 3 to 5 moist
Chroma: 3 or 4 dry or moist
Rock fragments: granogabbro, granodiorite, or rhyolite. 5 to 65 percent total rock fragments; 5 to 35 percent gravel, 10 to 40 percent cobbles, 0 to 15 percent stones.
Reaction: slightly acid (pH 6.1) to neutral (pH 7.3)
E/B and B/E horizons:
Rock fragments: granogabbro, granodiorite, or rhyolite; 35 to 70 percent total rock fragments; 10 to 35 percent gravel, 10 to 35 percent cobbles, 0 to 15 percent stones.
Reaction: slightly acid (pH 6.1) to neutral (pH 7.3)
E part:
Hue: 10YR or 2.5Y
Value: 6 or 7 dry, 4 or 5 moist
Chroma: 2 or 3 dry or moist
Texture (fine earth fraction): loam, sandy clay loam, and clay loam
B part:
Hue: 10YR or 2.5Y
Value: 6 or 7 dry, 3 to 5 moist
Chroma: 3 or 4 dry or moist
Texture (fine earth fraction): clay or clay loam
Bt horizon:
Hue: 10YR or 2.5Y
Value: 5 to 7 dry, 3 to 5 moist
Chroma: 2 to 4 dry or moist
Texture: CBX-C, CBX-CL, GRX-C, GRV-CL, GRV-C
Rock fragments: granogabbro, granodiorite, or rhyolite; 45 to 80 percent total rock fragments; 10 to 50 percent gravel, 10 to 60 percent cobbles, 0 to 15 percent stones.
Reaction: slightly acid (pH 6.1) to neutral (pH 7.3)
COMPETING SERIES: This is the Mortenson series. The Mortenson soils are dry for more than 30 days in summer and contain sandstone rock fragments.
GEOGRAPHIC SETTING: The Mountpoor soils formed in slope alluvium and colluvium from granogabbro, granodiorite, or rhyolite as sills and dikes in shale of the Mancos formation on mountain slopes and ridges. Slopes range from 15 to 65 percent. Elevation ranges from 9,400 to 10,800 feet. The mean annual temperature is about 33 to 39 degrees F. The mean annual precipitation is about 27 to 33 inches. The frost-free period is 50 to 65 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Baird Hollow and Lizardhead soils. The Baird Hollow soils are on footslopes of mountains and have a mollic epipedon. Lizardhead soils are on backslopes and summits and have a mollic epipedon.
DRAINAGE AND PERMEABILITY: Well drained; very high runoff; slow permeability.
USE AND VEGETATION: This soil is used for wood products. Native vegetation is currently seral aspen with and understory of slender wheatgrass, elk sedge, blue wildrye, aspen peavine, and common juniper. Potential native vegetation is Engelmann spruce and subalpine fir woodland with an understory of elk sedge, dwarf blueberry, common juniper, and kinnikinnick. It is in the Engelmann Spruce-Subalpine Fir Woodland Site, Forest Cover Type 206.
DISTRIBUTION AND EXTENT: Southwestern Colorado in LRR E and MLRA 48A. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Ouray Soil Survey Area, Uncompahgre National Forest, San Miguel County, Colorado, 1998. The name comes from Mount Poor.
REMARKS: Diagnostic horizons and features recognized in this pedon.
Ochric epipedon: the zone from 3 to 31 inches (E and E/B horizons)
Glossic horizon: the zone from 20 to 39 inches. (E/B and B/E horizons)
Argillic horizon: the zone from 31 to 69 inches. (Bt horizon)
Particle-size control section: the zone from 31 to 51 inches (B/E and part of the Bt horizon)
This pedon was classified in accordance with Keys to Soil Taxonomy, 7th Edition, 1996.