LOCATION MCNINCH MT
Established Series
REV. GFB-RJS
01/2012
MCNINCH SERIES
The McNinch series consists of very deep well drained soils that formed in colluvium derived from quartzite. These soils occur on hills and mountain slopes. Slopes are 15 to 60 percent. Mean annual precipitation is about 400 mm and mean air annual temperature is about 3 degrees C.
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive Calcic Haplocryolls
TYPICAL PEDON: McNinch very gravelly loam, in rangeland on a 20 percent slope at an elevation of 1987 meters (colors are for dry soil unless otherwise noted).
A1--0 to 13 cm; dark grayish brown (10YR 4/2) very gravelly loam, very dark grayish brown (10YR 3/2) moist; moderate fine and medium granular structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine, fine, and few medium roots; many very fine and fine tubular pores; 30 percent gravel, 10 percent cobbles and 5 percent stones; slightly alkaline (pH 7.4); clear wavy boundary.
A2--13 to 28 cm; brown (10YR 5/3) very cobbly loam, dark brown (10YR 3/3) moist; weak medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine and fine, and few medium roots; common very fine and fine irregular pores; 25 percent gravel, 25 percent cobbles and less than 1 percent stones; slightly alkaline (pH 7.6); clear smooth boundary. (combined thickness of A1, A2 horizons - 20 to 30 cm)
Bk--28 to 66 cm; pale brown (10YR 6/3) very cobbly sandy loam, brown (10YR 4/3) moist; weak coarse subangular blocky structure; slightly hard, very friable, slightly sticky and nonplastic; common very fine and fine roots; common very fine and fine irregular pores; 25 percent gravel, 30 percent cobbles and less than 1 percent stones; finely disseminated calcium carbonate, 30 percent fine and medium soft masses of calcium carbonate and common distinct calcium carbonate coats on rock fragments; violently effervescent; moderately alkaline (pH 8.4); gradual wavy boundary. (20 to 50 cm thick)
BCk--66 to 152 cm; light yellowish brown (10YR 6/4) extremely cobbly sandy loam, yellowish brown (10YR 5/4) moist; massive; soft, very friable, nonsticky and nonplastic; few very fine and fine roots; common very fine and fine irregular pores; 20 percent gravel, 55 percent cobbles and less than 1 percent stones; finely disseminated calcium carbonate and common distinct calcium carbonate coats on underside of rock fragments; violently effervescent; moderately alkaline (pH 8.2).
TYPE LOCATION: Beaverhead County, Montana; located about 610 meters east and 274 meters north of the southwest corner of sec. 2, T. 14S, R. 10W; Dixon Mountain topographic quadrangle; UTM 12T, 358223e, 4944608n, NAD 83.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 2 to 5 degrees C.
Mollic epipedon thickness - 20 to 30 cm
Depth to calcic horizon - 20 to 30 cm
Particle-size control section - averages less than 18 percent clay
A1, A2 horizons
Value: 4 or 5 dry; 3 or 4 moist
Chroma: 2 or 3; dry or moist
Clay content: 12 to 18 percent
Rock fragments: 35 to 60 percent--20 to 50 percent gravel, 5 to 25 percent cobbles, 0 to 10 percent stones
Reaction: pH 7.2 to 7.8
Bk horizon
Value: 6 to 8 dry; 4 or 5 moist
Chroma: 2 or 3; dry or moist
Texture: loam or sandy loam
Clay content: 12 to 17 percent
Rock fragments: 35 to 70 percent--20 to 40 percent gravel, 15 to 45 percent cobbles, 0 to 2 percent stones
Calcium Carbonate Equivalent: 20 to 35 percent
Reaction: pH 8.0 to 8.4
BCk horizons
Value: 6 to 8 dry; 5 to 7 moist
Chroma: 2 to 4; dry or moist
Texture: loam or sandy loam
Clay content: 12 to 17 percent
Rock fragments: 60 to 80 percent--20 to 40 percent gravel, 30 to 60 percent cobbles, 0 to 2 percent stones
Calcium Carbonate Equivalent: 15 to 30 percent
Reaction: pH 8.0 to 8.4
COMPETING SERIES:
Farlow (WY) - are deep to a lithic contact
Rockisland (MT) - average more than 18 percent clay in the particle-size control section
Silvercliff (CO) - have a lithologic discontinuity
Windicreek (ID) - have a xeric moisture regime
GEOGRAPHIC SETTING:
Landform - hills and mountain slopes
Elevation - 1950 to 2380 meters
Slope - 15 to 60 percent
Parent material - colluvium derived from quartzite
Climate - long, cold winters; moist springs; warm summers
Mean annual precipitation - 380 to 485 mm
Mean annual air temperature - 1 to 4 degrees C.
Frost-free period - 50 to 70 days
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: Well drained; moderate rapid permeability.
USE AND VEGETATION: McNinch soils are used mainly for rangeland and wildlife habitat. The vegetation is mainly bluebunch wheatgrass, kingspike fescue, POA (species), Idaho fescue, sagebrush, rubber rabbitbrush, and other miscellaneous forbs.
DISTRIBUTION AND EXTENT: McNinch soils are of small extent in southwestern Montana. MLRA - 43B.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES ESTABLISHED: Horse Prairie-South Valley Area - Part of Beaverhead County, Montana, 2011; proposed in Beaverhead County, Montana, 2009.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - from 0 to 28 cm (A1, A2 horizons)
Calcic horizon - from 28 to 152 cm (Bk, BCk horizons)
Particle-size control section - from 25 to 100 cm (part of A2, Bk, part of BCk horizons)
McNinch soils have a cryic temperature regime and an ustic moisture regime.
Taxonomic version: Eleventh Edition, 2010.
National Cooperative Soil Survey
U.S.A.