LOCATION GROSS IDEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Calcic Pachic Argixerolls
TYPICAL PEDON: Gross stony loam - rangeland. (Colors are for dry soil unless otherwise noted.)
A--0 to 9 inches; very dark grayish brown (10YR 3/2) loam, very dark brown (10YR 2/2) moist; weak thin platy and moderate fine and very fine granular structure; slightly hard, friable, slightly sticky, slightly plastic; many roots; many very fine interstitial pores; few basaltic stones and very fine pebbles; neutral (pH 6.6); clear smooth boundary.
BAt--9 to 19 inches; very dark grayish brown (10Yr 3/2) heavy loam, very dark brown (10YR 2/2) moist; weak medium subangular blocky structure; hard, firm, sticky, plastic; common fine roots; common very fine tubular pores; few basaltic stones and very fine angular pebbles; patchy thin clay films on peds; neutral (pH 6.6); clear wavy boundary. (4 to 12 inches thick)
Bt1--19 to 26 inches; dark grayish brown (10YR 4/2) clay loam, dark brown (10YR 3/3) moist; weak medium prismatic structure that parts to moderate medium, subangular blocky structure; hard, firm, very sticky, plastic; common fine roots; common very fine tubular pores; few basaltic stones and pebbles; continuous, thin, slightly darker clay films on peds; slightly acid (pH 6.5); clear wavy boundary. (5 to 8 inches thick)
Bt2--26 to 33 inches; brown (10YR 4/3) clay loam, dark brown (10YR 3/3) moist; moderate medium and fine subangular blocky structure; hard, firm, sticky, plastic; few fine roots; common very fine tubular pores; 5 percent basaltic stones and 10 percent very fine gravel; continuous thin clay films on peds; neutral (pH 6.8); gradual wavy boundary. (2 to 9 inches thick)
BC--33 to 36 inches; brown (7.5YR 4/3) stony loam, dark brown (7.5YR 3/3) moist; moderate fine subangular blocky structure; hard, firm, sticky, slightly plastic; few fine roots; many very fine tubular pores; 5 percent basaltic stones and 10 percent very fine gravel; continuous thin clay films on peds; neutral (pH 6.8); gradual wavy boundary. (2 to 9 inches thick)
R--36 inches; basalt bedrock; calcium carbonate veins and spots in cracks.
TYPE LOCATION: Gem County, Idaho; about 6 miles north of Emmett; 600 feet east and 900 feet north of the center of sec. 4, T. 7 N., R. 1 W.
RANGE IN CHARACTERISTICS:
Average annual soil temperature - 42 to 47 degrees F
Average summer soil temperature - 60 to 66 degrees F
Depth to bedrock - 20 to 40 inches
Soil moisture - usually moist but dry for 60 consecutive days or more in the 4 to 12 inch section within 3 months following the summer solstice in 7 out of 10 years.
Mollic epipedon thickness - 20 to 40 inches
Coarse fragments - 2 to 35 percent
Clay in argillic horizon - 24 to 35 percent
Reaction - neutral to slightly acid
A horizon
Value - 2 to 4 dry, 1 or 2 moist
Chroma - 1 or 2 dry and moist
Organic carbon - 2.0 to 3.5 percent in upper 6 inches
Structure - moderate or strong granular; weak platy or subangular blocky
Bt horizon
Hue - 7.5YR or 10YR
Value - 4 through 6 dry, 3 or 4 moist
Chroma - 2 or 3 dry and moist
Texture - L, CL, GR-L, GR-CL, GB-CL
Structure - weak prismatic, moderate subangular blocky
Base saturation - greater than 75 percent
Lime - below 30 to 36 inches or in cracks of bedrock
COMPETING SERIES: These are Clegg, Despain, Jensen (T) and Lize series. Clegg, Despain, Jensen and Lize soils lack bedrock within 40 inches of the surface. Clegg and Despain soils have moderate or strong accumulation of carbonates. Jensen soils also have a calcic horizon.
GEOGRAPHIC SETTING: Gross soils are on steep or very steep northerly slopes in hilly or mountainous uplands at elevations of 1,500 to 4,000 feet. Slopes range from 25 to 75 percent. The soils formed in residuum weathered from basalt or other bedrock, but the upper parts may have some loessal material. The climate has dry summers, a mean annual precipitation of 12 to 17 inches, including 3 to 7 feet of snowfall. The frost-free season is 105 to 130 days. Average annual air temperature is 40 to 45 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bakeoven, Gem, and Reywat soils and the competing Gemid and Gemson soils. Bakeoven soils have bedrock within 10 inches of the surface. Gem soils have mollic epipedons thinner than 20 inches, fine textures in the B2t horizon, and are mesic. Reywat soils have bedrock above 20 inches.
DRAINAGE AND PERMEABILITY: Well or somewhat excessively drained; medium or rapid runoff; moderately slow permeability.
USE AND VEGETATION: Used mostly for range. The natural vegetation is chiefly Idaho fescue, Sandberg bluegrass, bluebunch wheatgrass, bitterbrush, balsamroot, big sagebrush, and cheatgrass.
DISTRIBUTION AND EXTENT: Southern Idaho and probably nearby regions. Moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Gem County, Idaho, 1962.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - surface to 36 inches
Argillic horizon - the zone from 19 to 33 inches (the Bt horizons)
Basalt bedrock - at 36 inches
Carbonates - in cracks at 36 to 42 inches