LOCATION CRAMPTON MT
Established Series
Rev. PEM-JAL-EMM
07/2012
CRAMPTON SERIES
The Crampton series consists of well drained soils that are moderately deep to grus and deep to hard granite. These soils formed in slope alluvium, colluviums, and residuum from hard fine and coarse grained igneous rocks deposited over coarse grained granitic bedrock. They are on escarpments, ridges and hills. Slopes are 4 to 60 percent. Mean annual precipitation is about 17 inches, and mean annual air temperature is about 40 degrees F.
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Typic Argiustolls
TYPICAL PEDON: Crampton very cobbly sandy loam, bouldery, in rangeland (Colors are for dry soil unless otherwise noted).
A--0 to 11 inches; dark grayish brown (10YR 4/2) very cobbly sandy loam, very dark grayish brown (10YR 3/2) moist; weak medium and fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; many very fine and few fine and medium roots; many very fine and few fine pores; 25 percent cobbles and 20 percent gravel; neutral (pH 7.2); gradual wavy boundary. (7 to 15 inches thick)
Bt1--11 to 21 inches; yellowish brown (10YR 5/4) very cobbly sandy clay loam, dark yellowish brown (10YR 4/4) moist; moderate medium and fine subangular blocky structure; slightly hard, friable, moderately sticky and slightly plastic; many very fine and few fine and medium roots; many very fine and few fine tubular pores; many faint clay films on faces of peds and bridging sand grains; 25 percent cobbles and 20 percent gravel; neutral (pH 7.3); gradual wavy boundary.
Bt2--21 to 30 inches; brown (10YR 5/3) very cobbly coarse sandy loam, brown (10YR 4/3) moist; moderate medium subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; common very fine and few fine roots; many very fine and few fine tubular and interstitial pores; common faint clay films bridging sand grains; 25 percent cobbles and 30 percent gravel; neutral (pH 7.1); clear wavy boundary. (Combined thickness of Bt horizons is 10 to 25 inches).
BC--30 to 35 inches; pale brown (10YR 6/3) gravelly coarse sandy loam, brown (10YR 5/3) moist; weak medium and fine subangular blocky structure; soft, very friable, slightly sticky and nonplastic; 30 percent gravel; neutral (pH 6.8); clear wavy boundary. (0 to 10 inches thick)
Cr--35 to 59 inches; yellowish brown (10YR 5/4) decomposed granite bedrock (grus) that crushes to very gravelly loamy coarse sand; neutral (pH 7.0). (15 to 34 inches thick)
R--59 inches; hard granite bedrock.
TYPE LOCATION: Jefferson County, Montana; 100 feet north and 450 feet east of the SW corner of sec. 35, T. 8 N., R. 4 W.
RANGE IN CHARACTERISTICS:
Soil Temperature - 38 to 44 degrees F.
Moisture control section - between 4 and 12 inches.
Thickness of mollic epipedon - 7 to 15 inches.
Depth to Cr horizon: 20 to 40 inches.
Depth to R horizon: 40 to 60 inches.
Surface stones or boulders: 0 to 5 percent.
A horizon
Hue: 10YR or 2.5Y
Value: 3 or 4 dry; 2 or 3 moist;
Chroma: 1, 2 or 3
Texture: sandy loam, sandy clay loam or coarse sandy loam
Clay content: 10 to 25 percent
Rock fragments: 0 to 60 percent--0 to 5 percent stones, 0 to 25 percent cobbles, 0 to 30 percent gravel
Reaction: pH 6.6 to 7.3
Bt horizons
Hue: 10YR or 2.5Y
Value: 5 or 6 dry; 4 or 5 moist;
Chroma: 2, 3 or 4
Texture: coarse sandy loam, sandy clay loam, clay loam, or loam
Clay content: 18 to 35 percent
Rock fragments: 35 to 60 percent--0 to 5 percent stones, 5 to 25 percent cobbles, 20 to 45 percent gravel
Reaction: pH 6.1 to 7.3
BC horizon - Hue: 10YR or 2.5Y
Value: 5 or 6 dry; 4 or 5 moist
Chroma: 3, 4 or 6
Texture: coarse sandy loam or sandy loam
Clay content: 10 to 18 percent
Rock fragments: 15 to 50 percent--0 to 10 percent cobbles, 15 to 50 percent gravel (mostly less than 7mm in diameter)
Reaction: pH 6.1 to 7.3
COMPETING SERIES:
Bendire (CO) - has a lithic contact at 20 to 40 inches.
Blaincreek (MT) - has a lithic contact at 20 to 40 inches.
Borpark (CO) - does not have a lithic contact above 60 inches; has horizons of secondary carbonate accumulation; formed in materials derived mainly from basalt and shale.
Crackerville (MT) - has a lithic contact at 20 to 40 inches.
Curecanti (CO) -does not have a lithic contact above 60 inches; has hues reddera than 10YR; has more than 60 percent rock fragments.
Harol (UT) - does not have a lithic contact above 60 inches; has a lithologic discontinuity above 40 inches; has hues redder than 7.5YR in the C horizon.
Harpole (UT) - does not have a lithic contact above 60 inches; has hues redder than 10YR in the argillic and to a depth of 60 inches; has a very cobbbly or extremely gravelly loamy sand or sandy loam discontinuity above a depth of 40 inches.
Hilger (MT) - does not have a lithic contact above 60 inches; has calcic horizons.
Holter (MT) - does not have a lithic contact above 60 inches; has horizon of secondary carbonate accumulation.
Quinncreek (MT) - has a lithic contact at 20 to 40 inches; has horizons of secondary carbonate accumulation.
Sawbuck (MT) - does not have a lithic contact above 60 inches; depth to the base of the argillic greater than 40 inches.
Sawicki (MT) - does not have a lithic contact above 60 inches.
Shawmut (MT) - does not have a lithic contact above 60 inches; has calcic horizons.
Shirttail (SD) - does not have a paralithic contact above the lithic contact; has horizon of sandy-skeletal material above the lithic contact.
Wickes (MT) - has a lithic contact at 20 to 40 inches; has horizon of secondary carbonate accumulation.
Widtsoe (UT) - does not have a lithic contact above 60 inches; has calcic horizons; has hues redder than 10YR.
GEOGRAPHIC SETTING:
Landform - escarpments, ridges and hills.
Elevation - 4,400 to 6,000 feet.
Slope - 4 to 60 percent.
Parent material - slope alluvium, colluvium and residuum from hard fine and coarse grained igneous rocks deposited over coarse grained granitic bedrock.
Climate - long, cold winters; moist springs; warm summers.
Mean annual precipitation - 15 to 19 inches.
Mean annual air temperature - 36 to 42 degrees F.
Frost-free period - 70 to 105 days.
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: Well drained, moderate permeability.
USE AND VEGETATION: Crampton soils are primarily used for rangeland and wildlife habitat. The potential native vegetation is mainly rough fescue, Idaho fescue, bluebunch wheatgrass, prairie junegrass, lupine, fringed sagewort, arrowleaf balsamroot, cudweed sagewort, prickleypear cactus, and aster.
DISTRIBUTION AND EXTENT: Crampton soils are of small extent in southwestern Montana. MLRA 43B.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Jefferson County, Montana, 1998.
REMARKS: Soil interpretation record: MT3008, MT3030.
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - from the surface to 11 inches (A horizon);
Argillic horizon - from 11 to 30 inches (Bt1 and Bt2 horizons);
Particle size control section - from 11 to 30 inches (Bt1 and Bt2 horizons);
Paralithic contact - a layer of decomposed granite (grus) from 35 to 59 inches (Cr horizon);
Lithic contact - hard granite bedrock at 59 inches (R horizon).
Crampton soils have a frigid temperature regime and an ustic moisture regime.
National Cooperative Soil Survey
U.S.A.