LOCATION MOLAS CO+WYEstablished Series
TAXONOMIC CLASS: Fine, smectitic, frigid Typic Argialbolls
TYPICAL PEDON: Molas clay loam - grassland. (Colors are for dry soil unless otherwise noted.)
A11--0 to 5 inches; dark grayish brown (10YR 4/2) clay loam, very dark brown (10YR 2/2) moist; moderate fine crumb structure; soft, very friable, slightly sticky, slightly plastic; 10 percent fine gravel, 5 percent cobbles; medium acid; clear smooth boundary. (3 to 8 inches thick)
A12--5 to 13 inches; dark grayish brown (10YR 4/2) clay loam, very dark brown (10YR 2/2) moist; moderate very fine subangular blocky structure that parts to strong fine granules; slightly hard, very friable, slightly sticky, slightly plastic; peds are hard; 10 percent fine gravel, 5 percent cobbles; medium acid; clear smooth boundary. (0 to 12 inches thick)
A2--13 to 18 inches; light gray (10YR 7/2) clay loam, grayish brown (10YR 5/2) moist; medium, fine, distinct mottles yellowish brown (10YR 5/6) moist; moderate thin platy structure that parts to strong very fine granules; slightly hard, very friable, slightly sticky, slightly plastic; few small dark concretions; 5 percent fine gravel, 5 percent cobbles; medium acid; abrupt smooth boundary. (4 to 8 inches thick)
B2t--18 to 26 inches; grayish brown (10YR 5/2) clay, dark grayish brown (10YR 4/2) moist; many large prominent yellowish brown (10YR 5/6) mottles; strong medium angular blocky structure; slightly hard, very friable, sticky, plastic; peds are extremely hard; thin continuous clay films on peds and as coatings and fillings in root channels and in pores; few slickensides; medium acid; gradual wavy boundary. (5 to 40 inches thick)
B3--26 to 33 inches; yellowish brown (10YR 5/4) clay, dark yellowish brown (10YR 4/4) moist; common medium distinct dark gray (10YR 4/1) mottles; weak coarse angular blocky structure; hard, friable, sticky, plastic; peds are extremely hard; few shale chips; medium acid; gradual wavy boundary. (3 to 6 inches thick)
IIC--33 to 60 inches; gray and olive gray shale.
TYPE LOCATION: Hinsdale County, Colorado; NE1/4 Sec. 8, T. 37 N., R. 3 W.
RANGE IN CHARACTERISTICS: Depth to the paralithic contact ranges from 20 to 40 inches. Rock fragments range from 0 to 35 percent by volume in the A11, A12, and A2 horizons and are mainly less than 10 inches in diameter.
The A1 horizon has hue of 5Y through 7.5YR, value of 5 through 8 dry, 4 through 7 moist, and chroma of 1 through 4. It has few distinct to many prominent mottles. This horizon is medium acid or strongly acid.
The B2t horizon has hue of 5Y through 7.5YR, value of 5 through 7 dry, 4 through 6 moist, and chroma of 1 through 3. It is typically clay, and has 40 to 60 percent clay, 5 to 45 percent silt, and 2 to 15 percent sand. This horizon is strongly acid or medium acid.
The C horizon, if present, has hue of 5Y through 7.5YR. It is typically clay, and has 35 to 60 percent clay. This horizon is medium acid or strongly acid.
COMPETING SERIES: These are the Galchutt and Nettleton series. Galchutt and Nettleton soils lack a paralithic contact above a depth of 40 inches.
GEOGRAPHIC SETTING: The Molas soils are on gently to moderately sloping hillsides and concave slopes. Slopes typically range from about 4 to 65 percent. The soils formed in moderately thin noncalcareous fine textured materials originating as glacial till deposits over shale beds or as residuum from shale. At the type location the mean annual precipitation is 35 to 40 inches. Mean annual temperature is 42 degrees F., mean summer temperature is 60 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Aaberg and Pagosa soils. Aaberg soils lack an abrupt textural boundary at the upper margin of the B2t horizon and have better drainage. Pagosa soils have a mollic epipedon more than 16 inches thick, lack an abrupt textural boundary, and are well drained.
DRAINAGE AND PERMEABILITY: Poorly drained; medium to slow runoff; very slow permeability.
USE AND VEGETATION: These soils are used as native rangeland. Native vegetation is mainly carex, oatgrass, and cinquefoil.
DISTRIBUTION AND EXTENT: South-central Colorado. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Hinsdale County (Piedra Area), Colorado, 1974.
REMARKS: Last updated by the state 5/74.