LOCATION WOROCK MT
Established Series
Rev. BDD-JJU-EMM
05/2017
WOROCK SERIES
The Worock series consists of very deep, well drained soils that formed in colluvium, alluvium, till, or slide deposits derived from igneous, argillite, and metamorphic rock. These soils are on mountains, alluvial fans, stream terraces, moraines or landslides. Slopes are 4 to 85 percent. Mean annual precipitation is about 700 mm, and mean annual air temperature is about 3.9 degrees C.
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive Eutric Haplocryalfs
TYPICAL PEDON: Worock stony loam, forested (colors are for dry soil unless otherwise noted).
Oi--0 to 2 cm; slightly decomposed forest litter.
E--2 to 18 cm; light yellowish brown (10YR 6/4) stony loam, dark yellowish brown (10YR 4/4) moist; weak medium granular structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine and fine, and common medium roots; many very fine and fine irregular pores; 15 percent gravel, 5 percent cobbles, and 5 percent stones; moderately acid (pH 5.6); clear smooth boundary. (15 to 50 cm thick)
E/Bt--18 to 46 cm; E part (85 percent) very pale brown (10YR 7/4), Bt part (15 percent) yellowish brown (10YR 5/4) very gravelly clay loam, yellowish brown (10YR 5/6) moist for both parts; weak medium granular structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine and fine, and few medium roots; many very fine irregular pores; 25 percent gravel, 5 percent cobbles, and 5 percent stones; moderately acid (pH 5.6); clear smooth boundary. (0 to 75 cm thick)
Bt--46 to 71 cm; yellowish brown (10YR 5/6) very gravelly clay loam, dark yellowish brown (10YR 4/6) moist; weak medium subangular blocky structure parting to weak medium granular; hard, firm, moderately sticky and moderately plastic; common very fine and fine roots; common very fine irregular pores; many distinct clay films on faces of peds; 30 percent gravel, 10 percent cobbles, and 5 percent stones; moderately acid (pH 5.6); clear smooth boundary. (20 to 125 cm thick)
BC--71 to 160 cm; light yellowish brown (10YR 6/4) very gravelly sandy clay loam, dark yellowish brown (10YR 4/4) moist; massive; slightly hard, friable, moderately sticky and moderately plastic; few very fine and fine roots; few very fine irregular pores; 35 percent gravel, 15 percent cobbles, and 5 percent stones; moderately acid (pH 5.6). (0 to 90 cm thick)
TYPE LOCATION: Deer Lodge County, Montana; about 91 meters south and 222 meters west of the northeast corner of sec. 18, T. 2N, R. 12W.
RANGE IN CHARACTERISTICS:
Soil temperature - 2.8 to 8.3 degrees C.
Depth to top of argillic horizon - 14 to 50 cm
Note: Some pedons may have Bt/E horizons.
E horizon
Hue: 7.5YR, 10YR or 2.5Y; dry or moist
Value: 6 or 7 dry; 3 to 5 moist
Chroma: 2 to 6; dry or moist
Texture: loam or sandy loam
Clay content: 15 to 27 percent
Rock fragments: 10 to 50 percent--5 to 35 percent gravel, 0 to 20 percent cobbles, 0 to 20 percent stones
Reaction: pH 5.1 to 6.5
E/Bt horizon
Hue: E part - 2.5Y, 10YR or 7.5YR; dry or moist
Hue: Bt part - 10YR or 7.5YR; dry or moist
Value: E part - 6 or 7 dry; 3 to 5 moist
Value: Bt part - 5 or 6 dry; 4 or 5 moist
Chroma: E part - 2 to 6; dry or moist
Chroma: Bt part - 4 to 6; dry or moist
Texture: E part - loam or sandy loam
Texture: Bt part - clay loam
Texture: mixed - loam or clay loam
Clay content: E part - 15 to 27 percent
Clay content: Bt part - 27 to 35 percent
Clay content: mixed - 20 to 32 percent
Rock fragments: 20 to 60 percent--10 to 35 percent gravel, 0 to 15 percent cobbles, 0 to 20 percent stones
Reaction: pH 5.1 to 6.5
Bt horizon
Hue: 10YR or 7.5YR; dry or moist
Value: 5 to 7 dry; 4 or 5 moist
Chroma: 3 to 6; dry or moist
Texture: loam, clay loam or sandy clay loam
Clay content: 24 to 35 percent
Rock fragments: 35 to 65 percent--25 to 45 percent gravel, 5 to 20 percent cobbles, 0 to 10 percent stones
Reaction: pH 5.6 to 6.5
BC horizon
Hue: 10YR or 7.5YR; dry or moist
Value: 6 or 7 dry; 4 to 6 moist
Chroma: 3 to 6; dry or moist
Texture: loam, clay loam, sandy loam, or sandy clay loam
Clay content: 12 to 35 percent
Rock fragments: 35 to 60 percent--25 to 50 percent gravel, 0 to 15 percent cobbles, 0 to 10 percent stones
Reaction: pH 5.6 to 7.0
COMPETING SERIES:
Frisco (CO) - have horizons that have rock fragments that are dominantly stones
Helmville (MT) - have secondary calcium carbonate accumulation
Highwood (MT) - do not have an E horizon.
Lonniebee (MT) - are moderately deep to a lithic contact
Needleton (CO) - have hues of 5YR or 2.5YR in the argillic horizon
Tamarron (CO) - are moderately deep to a paralithic lithic
Tigeron (MT) - have argillic horizons consisting of lamellae
Watsondraw (WY) - have less than 35 percent rock fragments below the argillic horizon
GEOGRAPHIC SETTING:
Landform - mountains, alluvial fans, stream terraces, moraines and landslides
Elevation - 1,400 to 2,625 meters
Slope - 4 to 85 percent
Parent material - colluvium, alluvium, till, or slide deposits derived from igneous, argillite, and metamorphic rock
Climate - long, cold winters; moist springs; moist falls; warm, dry summers
Mean annual precipitation - 500 to 1,200 mm
Mean annual temperature - 1.7 to 7.2 degrees C.
Frost-free season - 30 to 70 days
GEOGRAPHICALLY ASSOCIATED SOILS: None listed.
DRAINAGE AND PERMEABILITY: Well drained; moderately slow permeability.
USE AND VEGETATION: Worock soils are used primarily for woodland and grazing. The potential native vegetation consists mainly of Douglas-fir and lodgepole pine with an understory of snowberry, Oregon grape, twinflower, grouse whortleberry, and other shrubs and grasses.
DISTRIBUTION AND EXTENT: Worock soils are of moderate extent central and western Montana. MLRAs - 43B, 44B.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES ESTABLISHED: Granite County, Montana, 1970. (Philipsburg-Drummond Area)
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - from 0 to 18 cm (Oi, E)
Argillic horizon - from 18 to 71 cm (E/Bt, Bt horizons)
Particle-size control section - from 18 to 68 cm (E/Bt, part of Bt horizons)
Worock soils have a cryic temperature regime and an udic moisture regime.
ADDITIONAL DATA: Soil interpretation records - MT0602, MT8107, MT0603.
National Cooperative Soil Survey
U.S.A.