LOCATION ASHBRAY MTEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, nonacid, frigid Lithic Ustorthents
TYPICAL PEDON: Ashbray gravelly coarse sandy loam, very bouldery, in woodland, (colors are for dry soil unless otherwise noted).
Oi--1/2 inch to 0; partially decomposed needles, twigs and leaves.
A--0 to 4 inches; grayish brown (10YR 5/2) gravelly coarse sandy loam, brown (10YR 4/3) moist; moderate medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine and fine roots; many very fine and common fine interstitial pores; 30 percent pebbles; neutral (pH 6.8); clear smooth boundary. (3 to 5 inches thick)
C--4 to 14 inches; pale brown (10YR 6/3) very gravelly coarse sandy loam, brown (10YR 5/3) moist; single grain; loose, nonsticky and nonplastic; common very fine and fine roots; 50 percent pebbles; neutral (pH 7.2); clear wavy boundary. (7 to 10 inches thick)
Cr--14 to 17 inches; yellowish brown (10YR 5/4) decomposed granitic bedrock (grus) that crushes to very gravelly coarse sand; neutral (pH 6.8). (0 to 5 inches thick)
R--17 inches; hard granite bedrock.
TYPE LOCATION: Jefferson County, Montana; 1900 feet north and 2175 feet east of the SW corner of section 17, T. 4 N., R. 3 W.
RANGE IN CHARACTERISTICS:
Soil Temperature - 38 to 44 degrees F
Moisture control section - between 4 and 12 inches, or between 4 inches and the lithic contact if bedrock is less than 12 inches deep.
Depth to Cr horizon - 8 to 18 inches.
Depth to bedrock - 12 to 20 inches.
Surface stones or boulders - 0 to 30 percent.
A horizon - Value: 5 or 6 dry, 4 or 5 moist
Chroma: 2, 3 or 4
Clay content: 10 to 20 percent
Rock fragments: 15 to 35 percent--0 to 10 percent cobbles and stones, 15 to 50 percent pebbles
Reaction: pH 6.1 to 7.3
C horizon - Value: 6 or 7 dry; 5, 6 or 7 moist
Chroma: 2, 3 or 4
Clay content: 5 to 18 percent
Rock fragments: 15 to 60 percent--0 to 10 percent cobbles and stones, 15 to 50 percent pebbles
Reaction: pH 6.1 to 7.3
A BC horizon is allowed.
COMPETING SERIES:
Ashbon (MT) - contains coarse fragments consisting dominantly of breccia; formed in residuum from volcanic mudflow breccia; is well drained.
Valto (CO) - contains 30 to 70 percent stones and cobbles; has lithic contact of sandstone; is well drained.
Zbart (MT) - has lithic contact at 5 to 10 inches.
GEOGRAPHIC SETTING:
Landform - mountains, hills and escarpments.
Elevation - 4,500 to 6,000 feet.
Slope- 2 to 70 percent.
Parent material - residuum derived from granite or other coarse grained igneous rocks.
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 15 to 19 inches.
Mean annual temperature - 36 to 42 degrees F.
Frost-free period - 70 to 105 days.
DRAINAGE AND PERMEABILITY: somewhat excessively drained, moderately rapid permeability.
USE AND VEGETATION: Ashbray soils are primarily used for woodland, understory grazing and for watershed. The potential native vegetation is mainly Douglas-fir and limber pine with an understory of common juniper, Rocky Mountain juniper, big sagebrush, Idaho fescue, prairie junegrass, bluebunch wheatgrass, and Sandberg bluegrass.
DISTRIBUTION AND EXTENT: Ashbray soils are of small extent in southwestern Montana.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Jefferson County, Montana, 1998.
REMARKS: Soil interpretation record: MT3096, MT3097, MT3098. Diagnostic horizons and features recognized in this pedon are: an ochric epipedon from the mineral surface to 4 inches (A horizon); a particle size control section from the surface to 14 inches (A and C horizons); a layer of decomposed granite (grus) from 14 to 17 inches (Cr horizon); hard granite bedrock at 17 inches (R horizon). Ashbray soils have a frigid temperature regime and an ustic moisture regime.