LOCATION YOUMAN COEstablished Series
TAXONOMIC CLASS: Fine, smectitic Vertic Argicryolls
TYPICAL PEDON: Youman loam - grassland. (Colors are for dry soil unless otherwise stated.)
A1--0 to 12 inches; very dark gray (10YR 3/1) loam, black (10YR 2/1) moist; moderate fine crumb and granular structure; soft, very friable; slightly sticky, slightly plastic; clear smooth boundary. (6 to 15 inches thick)
B1--12 to 17 inches; brown (7.5YR 5/3) clay loam, dark brown (7.5YR 4/3) moist; strong very fine subangular structure; slightly hard, very friable, slightly sticky, slightly plastic; peds are very hard, friable; thin patchy clay films on peds and in root channels and pores; few weak skeletans of bleached sand and silt; slightly acid; clear smooth boundary. (4 to 6 inches thick)
B2t--17 to 35 inches; reddish brown (5YR 5/3) light clay, reddish brown (5YR 4/3) moist; strong coarse angular blocky structure that parts to medium and fine angular blocks; slightly hard, very friable, sticky, plastic; peds are extremely hard, very firm; continuous clay films on peds and in root channels and pores; slightly acid; gradual smooth boundary. (6 to 25 inches thick)
B2t--35 to 40 inches; light reddish brown (5YR 6/4) heavy clay loam, reddish brown (5YR 5/4) moist; moderate coarse angular and subangular blocky structure; slightly hard, friable, sticky, plastic; peds are extremely hard, firm; thin patchy clay films on some peds and in root channels and pores; neutral; gradual smooth boundary. (4 to 14 inches thick)
C--40 to 60 inches; light reddish brown (5YR 6/4) heavy clay loam, reddish brown (5YR 5/4) moist; very weak coarse angular blocky structure; extremely hard, firm, sticky, plastic; neutral.
TYPE LOCATION: Gunnison County, Colorado; SW1/4 Sec. 21, T. 46 N., R. 4 W.
RANGE IN CHARACTERISTICS: Depth to uniformly calcareous material ranges from 40 to more than 60 inches. Depth to the base of the argillic horizon ranges from 15 to 50 inches. Rock fragments range from 0 to 15 percent by volume in a major part of the solum and C horizon above depth of 40 inches and are mainly less than 3 inches in diameter but range from 1/8 to 10 inches in diameter. The solum and C horizon range from slightly acid through mildly alkaline. The mean annual soil temperature is 40 degrees F., and the mean summer soil temperature is 45 degrees F. with an 0 horizon.
The A horizon has hue of 10YR through 5YR, value of 4 or 5 dry, 2 or 3 moist, and chroma of 1 through 3.
The B2t horizon has hue of 5YR through 10R, 5 through 7 dry, 3 through 6 moist, and chroma of 1 through 6. It is typically heavy clay loam or clay and has 35 to 50 percent clay, 5 to 45 percent silt and 15 to 55 percent sand with more than 15 percent being fine or coarser sand.
The C horizon has hue of 5YR through 10R. It is typically heavy clay loam or clay and averages more than 35 percent clay to depth of at least 50 inches.
COMPETING SERIES: These are the Arling, Brinkert, Brolliar, Buckskin, Florissant, Getta, Gothic, Gurney, Heath, Jerry, Judy, Little Horn, Mayoworth, Needleton, Owen Creek, Segal, Sessions, Sneffels, Trout Creek, and Waters series. Arling soils have a significant component of volcanic ash and other pyroclastics. Brinkert soils have hue of 7.5YR or yellower and have C horizons with less than 35 percent clay. Brolliar, Judy, Little Horn, Sneffels, and Waters soils have a lithic contact at depths of 20 to 40 inches. Buckskin and Sessions soils have sola more than 50 inches thick. Florissant, Mayoworth, Owen Creek, and Trout Creek soils have a paralithic contact at depths of less than 40 inches. Getta and Gothic soils have hue of 7.5YR or yellower. Gurney soils have coarse fragments that are mainly larger than 10 inches in diameter. Heath and Jerry soils are calcareous in the lower part of the solum and in the C horizon and have continuous horizons of secondary calcium carbonate. Needleton soils have hue of 7.5YR or yellower, have C horizons with less than 35 percent clay, and have coarse fragments that effervesce in acid throughout a noncalcareous matrix. Segal soils have an abrupt textural boundary between the A and B horizons and have hue of 7.5YR or yellower.
GEOGRAPHIC SETTING: The Youman soils are on moderately to steeply sloping upland alluvial fans and valley filling side slopes. The soils formed in parent materials derived principally from igneous rocks including rhyolite, tuff, and latite. At the type location the average annual precipitation is 20 inches with peak periods of precipitation occurring during the spring and summer. The mean annual temperature is 36 degrees F., mean summer temperature is 54 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Passar and Cochetopa soils. Passar soils have more than 35 percent coarse fragments in the solum. Cochetopa soils have mollic epipedons thicker than 16 inches and have hue of 7.5YR or yellower.
DRAINAGE AND PERMEABILITY: Well drained; medium to rapid runoff; slow permeability.
USE AND VEGETATION: These soils are used as native pastureland, wildlife habitat and for recreational purposes. Native vegetation is mainly big sagebrush, Thurber's fescue, Idaho fescue, bluegrass and scattered clumps of aspen.
DISTRIBUTION AND EXTENT: Mountainous areas of central Colorado. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Gunnison County, Colorado, 1974.
REMARKS: OSED scanned by NSSQA and cleaned up by Colorado. Last revised by state on 8/74.