LOCATION WELLSBASIN CO
Established Series
Rev. CRP/JCK
04/2019
WELLSBASIN SERIES
The Wellsbasin series consists of very deep, well drained soils that formed in slope alluvium, colluvium or slide deposits. These soils are on dipslopes, escarpments, fan remnants and landslides. Slopes are 3 to 65 percent. Mean annual precipitation is about 356 mm, and mean annual air temperature is 8.3 degrees C.
TAXONOMIC CLASS: Clayey-skeletal, mixed, superactive, mesic Calcidic Argiustolls
TYPICAL PEDON: Wellsbasin very cobbly loam, on a 36 percent concave, south-facing slope at an elevation of 2,170 meters. The surface is covered with 10 percent stones. (Colors are for dry soil unless otherwise noted.)
A--0 to 18 cm; brown (10YR 4/3) very cobbly loam, very dark grayish brown (10YR 3/2) moist; weak fine and medium subangular blocky structure parting to weak fine and medium granular; soft, very friable, slightly sticky and slightly plastic; many very fine and fine, and common medium and coarse roots; 30 percent gravel, 20 percent cobbles and 5 percent stones; slightly alkaline (pH 7.6); clear wavy boundary. (15 to 25 cm thick)
Bt1--18 to 28 cm; brown (7.5YR 5/3) very cobbly clay loam, dark brown (7.5YR 3/3) moist; weak fine and medium subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; many very fine and fine, and common medium and coarse roots; few fine dendritic tubular pores; 30 percent faint clay films on all ped faces and on surfaces along pores; 30 percent gravel, 20 percent cobbles and 5 percent stones; slightly alkaline (pH 7.4); clear wavy boundary.
Bt2--28 to 33 cm; brown (7.5YR 5/3) very cobbly clay loam, brown (7.5YR 4/3) moist; moderate fine and medium subangular blocky structure; hard, friable, moderately sticky and moderately plastic; common very fine and fine, and few medium and coarse roots; common fine and medium dendritic tubular pores; 60 percent distinct clay films on all ped faces and on surfaces along pores; 30 percent gravel, 20 percent cobbles and 5 percent stones; slightly alkaline (pH 7.4); clear wavy boundary. (Combined thickness of Bt horizons is 12 to 30 cm)
Btk1--33 to 69 cm; light brown (7.5YR 6/4) very gravelly clay loam, brown (7.5YR 5/3) moist; moderate medium and coarse subangular blocky structure; hard, firm, moderately sticky and moderately plastic; few fine, medium, and coarse roots; common fine and medium dendritic tubular, and few fine vesicular pores; 60 percent distinct clay films on all ped faces and on surfaces along pores; 15 percent carbonate coats on surfaces of rock fragments; 15 percent fine, medium, and coarse irregular shaped carbonate masses in the matrix; 30 percent gravel, 5 percent cobbles and 5 percent stones; strongly effervescent; moderately alkaline (pH 8.4); gradual wavy boundary.
Btk2--69 to 79 cm; pale brown (10YR 6/3) silty clay loam, brown (10YR 5/3) moist; weak medium and coarse subangular blocky structure; hard, friable, moderately sticky and moderately plastic; few fine, medium, and coarse roots; few fine dendritic tubular and vesicular pores; 10 percent faint clay films on all ped faces; 10 percent carbonate coats on surfaces of rock fragments; 10 percent fine, medium, and coarse irregular shaped calcium carbonate masses in the matrix; 10 percent gravel and 2 percent cobbles; strongly effervescent; moderately alkaline (pH 8.4); gradual wavy boundary. (Combined thickness of Btk horizons is 20 to 50 cm)
Bk--79 to 119 cm; very pale brown (10YR 7/3) silty clay loam, brown (10YR 5/3) moist; weak medium and coarse subangular blocky structure; hard, friable, moderately sticky and moderately plastic; few fine and medium roots; few fine dendritic tubular and vesicular pores; 5 percent carbonate coats on surfaces of rock fragments; 5 percent fine and medium irregular shaped calcium carbonate masses in the matrix; violently effervescent; 5 percent gravel; moderately alkaline (pH 8.4); gradual wavy boundary. (15 to 50 cm thick)
C--119 to 152 cm; brownish yellow (10YR 6/6) silt loam; yellowish brown (10YR 5/4) moist; massive; slightly hard, friable, moderately sticky and slightly plastic; few fine roots; violently effervescent; 5 percent gravel; moderately alkaline (pH 8.4).
TYPE LOCATION: Ouray County, Colorado; about 137 meters north and 320 meters east of the southwest corner of Section 14, T. 46N, R. 8W. Dallas topographical quadrangle; 38 degrees, 13 minutes, 57.5 seconds N, 107 degrees, 43 minutes, 7 seconds W.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 8 to 11 degrees C
Mollic epipedon thickness - 25 to 40 cm
Particle size control section (weighted average):
Clay content - 35 to 50 percent
Rock fragments - 35 to 60 percent; 20 to 35 percent gravel, 15 to 35 percent cobbles, 0 to 10 percent stones
A horizon
Hue: 7.5YR or 10YR
Value: 4 or 5 dry; 2 or 3 moist
Chroma: 2 or 3
Texture: loam, sandy loam, sandy clay loam
Clay content: 14 to 27 percent
Rock fragments: 35 to 60 percent; 20 to 35 percent gravel, 15 to 35 percent cobbles, 0 to 10 percent stones
Reaction: pH 7.0 to 7.8
Bt horizons
Hue: 7.5YR or 10YR
Value: 4, 5 or 6 dry; 3 or 4 moist
Chroma: 2, 3, or 4
Texture: clay loam or clay
Clay content: 30 to 50 percent
Rock fragments: 35 to 60 percent; 20 to 35 percent gravel, 15 to 35 percent cobbles, 0 to 10 percent stones
Reaction: pH 7.0 to 7.8
Btk horizons
Hue: 7.5YR or 10YR
Value: 5, 6, or 7 dry; 4, 5, or 6 moist
Chroma: 2, 3, or 4
Texture: clay loam or clay
Clay content: 27 to 45 percent
Rock fragments: 5 to 60 percent; 5 to 35 percent gravel, 0 to 25 percent cobbles, 0 to 10 percent stones
Calcium carbonate equivalent: 5 to 30 percent
Reaction: pH 8.0 to 8.4
Bk horizon
Hue: 7.5YR or 10YR
Value: 5, 6, or 7 dry; 4, 5, or 6 moist
Chroma: 2, 3, or 4
Texture: clay loam or clay
Clay content: 27 to 45 percent
Rock fragments: 5 to 60 percent; 5 to 35 percent gravel, 0 to 25 percent cobbles, 0 to 10 percent stones
Calcium carbonate equivalent: 15 to 30 percent
Reaction: pH 8.0 to 8.4
C horizon (where present)
Hue: 7.5YR or 10YR
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 2, 3, or 4
Texture: sandy clay loam, clay loam, loam or sandy loam
Clay content: 15 to 35 percent
Rock fragments: 5 to 25 percent; 5 to 20 percent gravel, 0 to 10 percent cobbles
Reaction: pH 7.8 to 8.4
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING:
Landform - dipslopes, escarpments, fan remnants and landslides
Elevation - 1,829 to 2,286 meters
Slope - 3 to 65 percent
Parent Material - slope alluvium, colluvium or slide deposits
Mean annual air temperature - 7.2 to 10 degrees C
Mean annual precipitation - 305 to 406 mm
Frost-free period - 105 to 155 days
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: Well drained; moderately slow permeability.
USE AND VEGETATION: Wellsbasin soils are used primarily for rangeland and recreation. Native vegetation is twoneedle pinyon, Utah juniper, western wheatgrass, Indian ricegrass, Sandberg bluegrass and Wyoming big sagebrush.
DISTRIBUTION AND EXTENT: Wellsbasin soils are of small extent in southwest Colorado. MLRA 36 and 48A.
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Ouray County, Colorado - Ridgway Area, Colorado, Parts of Delta, Gunnison, Montrose, and Ouray Counties, 2019.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - from 0 to 28 cm (A and Bt1 horizons)
Argillic horizon - from 18 to 79 cm (Bt1, Bt2, Btk1 and Btk2 horizons)
Calcic horizon - from 33 to 119 cm (Btk1, Btk2 and Bk horizons)
Particle-size control section - from 18 to 68 cm (Bt1, Bt2 and part of Btk1 horizon)
Wellsbasin soils have a mesic temperature regime and an ustic moisture regime bordering on aridic.
National Cooperative Soil Survey
U.S.A.