LOCATION STUMPP COEstablished Series
TAXONOMIC CLASS: Clayey over sandy or sandy-skeletal, smectitic over mixed Typic Natricryolls
TYPICAL PEDON: Stumpp clay loam - grassland. (Colors are for dry soil unless otherwise noted.)
A1--0 to 3 inches; very dark gray (10YR 3/1) clay loam, very dark brown (10YR 2/2) moist; strong medium granular structure; soft, very friable, slightly sticky, slightly plastic; calcareous; strongly alkaline (pH 8.6); abrupt smooth boundary. (2 to 5 inches thick)
B2tsa--3 to 16 inches; very dark gray (10YR 3/1) clay, black (10YR 2/1) moist; moderate medium columnar structure that parts to fine angular blocks; slightly hard, very friable, very sticky, very plastic; peds are extremely hard, very firm; thin continuous wax-like coatings on faces of peds and in root channels and pores; visible calcium carbonate and other salts as small concretions and crystals; calcareous; very strongly alkaline (pH 9.2); gradual wavy boundary. (7 to 20 inches thick)
B3sa--16 to 26 inches; very dark gray (10YR 3/1) clay, black (10YR 2/1) moist; moderate medium angular blocky structure; slightly hard, friable, very sticky, very plastic; peds are extremely hard, firm; glossy patches on faces of peds and some glossy coatings in root channels and pores, visible calcium carbonate and other salts as crystals, and concretions; very strongly alkaline (pH 9.2); gradual wavy boundary. (6 to 15 inches thick)
Clsa--26 to 32 inches; gray (2.5Y 5/1) clay, dark gray (2.5Y 4/1) moist; massive; extremely hard, very firm, sticky, plastic; visible secondary calcium carbonate, calcium sulfate and other salts as concretions, crystals, and in small seams and streaks; calcareous; strongly alkaline (pH 8.6); abrupt wavy boundary. (0 to 25 inches thick)
IIC2--32 to 60 inches; very gravelly loamy sand.
TYPE LOCATION: Jackson County, Colorado; 750 feet east and 400 feet south of W1/4 corner Sec. 13, T. 7 N., R. 79 W.
RANGE IN CHARACTERISTICS: The mollic epipedon ranges from 16 to 25 inches thick. Thin and inconsistent A2 horizons occur in some pedons. Depth to uniformly calcareous material ranges from 0 to 6 inches. Depth to the sandy-skeletal IIC horizon ranges from 20 to 40 inches. Depth to the base of the argillic horizon ranges from 15 to 36 inches. Depth to continuous subhorizons of visible secondary calcium carbonate and other soluble salts range from 3 to 30 inches. Some visible salt accumulation normally occurs throughout the B2t horizons but may be deeper in some pedons. Conductivity ranges from less than 1 to 15 millimhos in the solum. ESP ranges from 15 to 30 percent in the solum but increases with depth and exceeds 30 percent in the Csa horizon of some pedons. Mottling within the control section not due to segregation of lime ranges from fine faint mottles to common distinct mottles below the mollic epipedon. Rock fragments range from 0 to 35 percent by volume in a major part of the solum and C horizon above the IIC horizon and are mainly 1/4 to 10 inches in diameter.
The A horizon has hue of 5Y through 7.5YR, value of 3 through 5 try, 2 or 3 moist, and chroma of 1 through 3. It ranges from mildly alkaline to very strongly alkaline.
The B2t horizon has hue of 5Y through 7.5YR, value of 3 through 6 dry, 2 through 5 moist, and chroma of 1 through 4. It is typically heavy clay loam or clay and averages 35 to 60 percent clay, 5 to 50 percent silt, and 10 to 40 percent sand. This horizon ranges from moderately alkaline to very strongly alkaline.
The C horizon has hue of 5Y through 7.5YR; subhorizons redder than 7.5YR occur in some pedons. It ranges from strongly to very strongly alkaline and has 3 to 4 percent calcium carbonate equivalent.
COMPETING SERIES: These are the Martinson and Spicerton series. Martinson and Spicerton soils lack a sandy-skeletal C horizon. Also, Spicerton soils lack a mollic epipedon.
GEOGRAPHIC SETTING: Stumpp soils are on flood plains and in concave drainageways. Slopes typically range from 0 to about 6 percent. These soils formed in moderately thin, calcareous, fine textured alluvial materials overlying sand and gravel beds. At the type location the average annual precipitation is 15 inches with peak periods of precipitation in the spring and early summer. Mean annual temperature is 38 degrees F. and mean summer temperature is 56 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Brinkert soils and the competing Spicerton soils. Brinkert soils lack a natric horizon and sandy-skeletal C horizons.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; slow runoff; slow permeability. Water tables generally occur within the IIC horizon of these soils turning some seasons.
USE AND VEGETATION: They are used as native pastureland. Native vegetation is sagebrush, bluegrass, pussy toes, and willows,
DISTRIBUTION AND EXTENT: Mountain valleys of Colorado and Wyoming. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Star Valley Soil Conservation District, Wyoming, 1943.
REMARKS: OSED scanned by NSSQA and cleaned up by Colorado. Last revised by state on 11/73.