LOCATION BLACKLEED MT+IDEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive Lamellic Haplocryepts
TYPICAL PEDON: Blackleed gravelly sandy loam - native shrubs and conifers. (Colors are of dry soil unless otherwise noted.)
A--0 to 4 inches; dark grayish brown (10YR 4/2) gravelly sandy loam, black (10YR 2/1) moist; moderate medium and fine granular structure; soft, very friable, many fine roots; 20 percent gravel; noncalcareous; clear wavy boundary. (2 to 6 inches thick)
A&B1--4 to 14 inches; light yellowish brown (10YR 6/4) gravelly sandy loam, dark yellowish brown (10YR 4/4) moist; weak medium and fine subangular blocky structure; soft, very friable, slightly sticky; many fine roots; 3 loam lamellae 1/4 inch thick and 4 inches apart; 35 percent gravel; noncalcareous; clear wavy boundary. (8 to 18 inches thick)
A&B2--14 to 26 inches; reddish yellow (7.5YR 6/6) extremely gravelly loam, brown (7.5YR 4/4) moist; weak medium and fine subangular blocky structure; soft, very friable, slightly sticky, slightly plastic; many fine roots; loam lamellae as in above horizon; 65 percent gravel; noncalcareous; clear wavy boundary. (8 to 16 inches thick)
C--26 to 40 inches; yellow (10YR 7/6) extremely gravelly sandy loam, strong brown (7.5YR 5/6) moist; weak fine subangular blocky structure; soft, very friable, slightly sticky; common roots; 75 percent gravel; many pebbles are subangular partially weathered granitic rock fragments; noncalcareous. (12 inches and thicker)
TYPE LOCATION: Mineral County, Montana; 800 feet east and 1,900 feet north of SW corner sec. 35, T.12N., R.25W.
RANGE IN CHARACTERISTICS: Blackleed soils have profile textures ranging from sandy loam to loam with from 5 to 15 percent clay and have increasing quantity of igneous pebbles ranging from 20 to 35 percent in the surface horizons to 60 to 70 percent in substrata horizons. They range from slightly to strongly acid and have an estimated 40 to 85 percent base saturation. Mean annual soil temperature ranges from 40 degrees to 43 degrees F. and the average summer soil temperature ranges from 50 degrees to 55 degrees F. Hue ranges from 2.5Y to 7.5YR. Solum thickness ranges from 20 to 40 inches and depth to bedrock is more than 40 inches. The A1 horizon has value of 3 through 5 and chroma of 1 or 2. The A&B horizon has value of 6 or 7 and chroma of 3 through 6. Lamellae of accumulated clay comprise from 1 to 5 percent of the soil mass. Cusps of illuvial clay are on the undersides of some pebbles and stones.
COMPETING SERIES: This is the Evaro series. Evaro soils have an ash influenced surface layer.
GEOGRAPHIC SETTING: Blackleed soils are on steep mountain slopes and rounded divides at elevations of about 5,000 feet along the Idaho Divide where granitic extrusives of the Idaho Batholith occur. Mean annual temperatures are estimated at 35 degrees to 42 degrees F. and mean summer air temperatures are estimated at 42 degrees to 52 degrees F. Mean annual precipitation is estimated at 35 to 50 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Coerock, Holloway, and Truefissure soils. Coerock soils are thin silty soils less than 20 inches deep over hard metasedimentary bedrock. Holloway and Truefissure soils are deep silty soils with a brown loess mantle.
DRAINAGE AND PERMEABILITY: Well-drained; moderately rapid permeability.
USE AND VEGETATION: Mainly shrubs and grasses with scattered stands of conifers. Summer game range with some domestic stock grazing.
DISTRIBUTION AND EXTENT: The Blackleed series is inextensive, occurring at high elevations in the Rocky Mountains in western Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: St. Regis-Nine Mile Area, Mineral County, Montana, 1970.
The 3/2008 description reflects a change in classification from Loamy-skeletal, mixed, superactive Lamellic Eutrocryepts to Loamy-skeletal, mixed, superactive Lamellic Haplocryepts due to revision of the cryepts great groups and subgroups. The competing series section was not updated and should be reviewed after all the cryepts have been re-classified.