LOCATION HALF MOON MTEstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, active, frigid Typic Glossudalfs
TYPICAL PEDON: Half Moon silt loam, forested (colors are for dry soil unless otherwise noted).
Oi--0 to 2 inches; undecomposed and slightly decomposed forest litter.
E--2 to 6 inches; very pale brown (10YR 8/2) silt loam, light brownish gray (10YR 6/2) moist; moderate thin platy structure; slightly hard, very friable, slightly sticky and slightly plastic; many fine roots and pores; very strongly acid (pH 5.0); clear wavy boundary. (4 to 11 inches thick)
E/Bt--6 to 13 inches; E part (75 percent) is very pale brown (10YR 8/2) silt loam, light brownish gray (10YR 6/2) moist which tongues into the B part; B part (25 percent) is very pale brown (10YR 7/3) silty clay loam, brown (10YR 5/3) moist; texture mixed is silt loam; weak thick platy structure parting to strong medium subangular blocky; hard, friable, slightly sticky, and slightly plastic; many fine roots and pores; slightly acid (pH 6.5); clear wavy boundary. (2 to 9 inches thick)
Bt--13 to 24 inches; very pale brown (10YR 7/3) silty clay loam, brown (10YR 5/3) moist; moderate medium subangular blocky structure; hard, friable, moderately sticky and moderately plastic; many fine and very fine roots; common fine and very fine pores; common thin clay films on faces of peds and in pores; neutral (pH 7.0); clear wavy boundary. (10 to 20 inches thick)
Bk1--24 to 28 inches; pale brown (10YR 6/3) silt loam, brown (10YR 5/3) moist; weak coarse subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common fine roots; few fine pores; few fine soft masses of lime; strongly effervescent; slightly alkaline (pH 7.7); clear irregular boundary. (4 to 6 inches thick)
Bk2--28 to 33 inches; pale brown (10YR 6/3) silt loam, brown (10YR 5/3) moist; moderate thick platy structure parting to moderate medium subangular blocky; slightly hard, friable, slightly sticky and slightly plastic; few very fine pores; common filaments and soft masses of lime; strongly effervescent; moderately alkaline (pH 8.0); abrupt boundary. (0 to 8 inches thick)
C--33 to 60 inches; very pale brown (10YR 7/3) very fine sandy loam that has thin lenses of silt loam and silty clay, pale brown (10YR 6/3) moist; massive; strongly effervescent; moderately alkaline (pH 8.0).
TYPE LOCATION: Flathead County, Montana; 2,300 feet south and 400 feet west of the NE corner of sec. 6, T. 30 N., R. 22 W.
RANGE IN CHARACTERISTICS:
Soil temperature - 42 to 46 degrees F.
Moisture control section - between 4 and 12 inches.
Control section - 25 to 35 percent clay.
Depth to secondary calcium carbonate accumulation - 14 to 35 inches.
Some pedons have a thin, discontinuous A horizon.
E horizon
Hue: 2.5Y, 10YR, or 7.5YR dry or moist
Value: 6, 7, or 8 dry; 4, 5, 6, or 7 moist
Chroma: 1, 2, or 3 dry or moist
Texture: silt loam or very fine sandy loam
Clay content: 15 to 25 percent
Rock fragments: 0 to 15 percent--0 to 10 percent cobbles, 0 to 5 percent gravel
Reaction: pH 4.5 to 7.3
E/Bt horizon
Hue: E part 2.5Y, 10YR, or 7.5YR; B part 2.5Y, 10YR or 7.5YR dry or moist
Value: E part 7 or 8, B part 6 or 7 dry; E part 6 or 7, B part 4, 5, or 6 moist
Chroma: E part 2 or 3; B part 3 or 4 dry or moist
Texture: silt loam or silty clay loam
Clay content: 15 to 25 percent
Rock fragments: 0 to 10 percent--0 to 5 percent cobbles, 0 to 5 percent gravel
Reaction: pH 4.5 to 7.3
Bt horizon
Hue: 2.5Y, 10YR, or 7.5YR dry or moist
Value: 6 or 7 dry; 4, 5, or 6 moist
Chroma: 3 or 4 dry or moist
Texture: silt loam or silty clay loam
Clay content: 25 to 35 percent
Rock fragments: 0 to 10 percent gravel
Reaction: pH 6.1 to 7.8
Bk horizon
Hue: 2.5Y, 10YR, or 7.5YR dry or moist
Value: 6 or 7 dry, 5 or 6 moist
Chroma: 2, 3, or 4 dry or moist
Texture: silt loam or silty clay loam
Clay content: 20 to 30 percent
Calcium carbonate equivalent: 5 to 15 percent
EC: 0 to 4 mmhos/cc
Reaction: pH 7.4 to 8.4
C horizon
Hue: 2.5Y, 10YR, or 7.5YR dry or moist
Value: 6 or 7 dry, 5 or 6 moist
Chroma: 2, 3, or 4 dry or moist
Texture: mainly very fine sandy loam, silt loam, or silty clay loam that has thin lenses of silty clay
Clay content: 20 to 30 percent
EC: 0 to 4 mmhos/cc
Reaction: pH 7.8 to 9.0
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING:
Landform- lake plains, glaciolacustrine stream terraces, and alluvial fans.
Elevation - 2,500 to 4,500 feet.
Slope - 0 to 45 percent.
Parent material - lacustrine deposits.
Climate - cool, with long, cold winters; moist springs; and warm summers.
Mean annual precipitation - 18 to 30 inches, much of which falls as snow or as spring rain.
Mean annual temperature - 38 to 44 degrees F.
Frost-free period - 70 to 105 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Depew, Entente, Haskill, Lubrecht, and Tarkio soils. Depew and Lubrecht soils are fine. Entente soils are coarse-silty and do not have argillic horizons. Haskill soils are coarse-loamy. Tarkio soils are very-fine.
DRAINAGE AND PERMEABILITY: Well drained; slow to rapid runoff; moderately slow permeability.
USE AND VEGETATION: Half Moon soils are used mainly for timber production, woodland grazing, and as wildlife habitat. The potential native vegetation is coniferous forest consisting mainly of grand fir, lodgepole pine, ponderosa pine, Engelmann spruce, Douglas-fir, and western larch with an understory of twinflower, queencup beadlily, bunchberry dogwood, dwarf huckleberry, pinegrass, kinnikinnick, common snowberry, white spirea, Oregon grape, white spirea, and elk sedge.
DISTRIBUTION AND EXTENT: Half Moon soils are of moderate extent in intermountain valleys of western Montana. MLRA 43A and 44A.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Flathead County (Upper Flathead Valley Area), Montana, 1957.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - from the soil surface to 13 inches (Oi, E, E/Bt horizons);
Albic horizon - from 2 to 6 inches (E horizon);
Glossic horizon - from 6 to 13 inches (E/Bt horizon);
Argillic horizon - from 13 to 24 inches (Bt horizon);
Particle-size control section - from 13 to 24 inches (Bt horizon).
Half Moon soils have a frigid temperature regime and a udic moisture regime bordering on ustic.