LOCATION SHENON IDEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Calciargidic Argixerolls
TYPICAL PEDON: Shenon loam--on a 5 percent smooth northeast-facing slope in rangeland at 5,700 feet elevation. (Colors are for dry soil unless otherwise noted. When described on October 20, 1982 the soil was dry to a depth of 60 inches.)
A--0 to 4 inches; brown (10YR 5/3) loam, dark brown (10YR 3/3) moist; weak very thin platy structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine and few fine, medium and coarse roots; many very fine interstitial pores, 10 percent pebbles, neutral (pH 7.2); clear wavy boundary. (3 to 7 inches thick)
Bt1--4 to 9 inches; brown (10YR 5/3) clay loam, dark brown (10YR 3/3) moist; moderate very fine, fine and medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine and few fine, medium and coarse roots; many very fine interstitial pores; common faint lay films in pores and on faces of peds; 5 percent pebbles; slightly alkaline (pH 7.6); clear wavy boundary. (3 to 7 inches thick)
Bt2--9 to 14 inches; pale brown (10YR 6/3) gravelly clay loam, dark brown (10YR 4/3) moist; strong very fine, fine and medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; common very fine and few fine medium roots; common very fine interstitial and few very fine tubular pores; many faint clay films in pores and on faces of peds; 20 percent pebbles; moderately alkaline (pH 8.0); abrupt wavy boundary. (3 to 7 inches thick)
Bk1--14 to 21 inches; very pale brown (10YR 7/3) gravelly clay loam, brown (10YR 5/3) moist; moderate very fine, fine and medium subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; common very fine and few fine roots; common very fine interstitial pores; 30 percent pebbles; strongly effervescent; strongly alkaline (pH 8.8); clear wavy boundary. (7 to 14 inches thick)
Bk2--21 to 24 inches; very pale brown (10YR 7/3) gravelly clay loam, yellowish brown (10YR 5/4) moist; massive; slightly hard, very friable, slightly sticky and slightly plastic; common very fine roots; common very fine tubular and interstitial pores; 20 percent pebbles; 5 percent cobbles; strongly effervescent; strongly alkaline (pH 8.8); gradual wavy boundary. (3 to 13 inches thick)
Bk3--24 to 40 inches; very pale brown (10YR 7/4) gravelly loam, yellowish brown (10YR 5/4) moist; massive; slightly hard, very friable, slightly sticky and slightly plastic; many very fine interstitial pores; 30 percent pebbles; strongly effervescent; strongly alkaline (pH 8.6); gradual wavy boundary. (15 to 20 inches thick)
Bk4--40 to 60 inches; very pale brown (10YR 7/4) loam, dark yellowish brown (10YR 4/4) moist; massive; slightly hard, very friable, slightly sticky and slightly plastic; 10 percent pebbles; strongly effervescent; strongly alkaline (pH 8.8).
TYPE LOCATION: Lemhi County, Idaho; about 3.5 miles northwest of Lemhi, Idaho; about 2,000 feet north and 2,600 feet east of the southwest corner of section 24, T. 18 N., R. 23 E. Latitude - 44 degrees, 52 minutes, 25 seconds North; Longitude - 113 degrees, 40 minutes, 45 seconds West.
RANGE IN CHARACTERISTICS:
Average annual soil temperature - 39 to 45 degrees F.
Mollic thickness - 7 to 12 inches
Depth to calcic horizon - 9 to 16 inches
Control section; percent clay - 24 to 34
Coarse fragments - 5 to 30 percent
A horizon
Chroma - 2 or 3 dry or moist
Value - 5 or 6 dry, 3 or 4 moist
Bt horizon
Value - 5 or 6 dry, 3 or 4 moist
Texture - L, CL, or GR-CL
Reaction - slightly or moderately alkaline
Bk horizon
Hue - 7.5YR or 10YR
Value - 6 or 7 dry, 4 through 7 moist
Chroma - 3 through 6 dry and moist
Texture - L, GR-L, CB-L, CL, or GR-CL
Rock fragments - 5 to 30 percent
COMPETING SERIES: These are the Dishpan, Eldgin(T), Fenelon, Singletree and Techick, and Techicknot soils. Dishpan soils are moderately deep to basalt bedrock. Eldgin soils have hues redder than 10YR in the Bt horizon. Singletree soils are deeper than 16 inches to secondary carbonates. Fenelon soils are moderately deep to a paralithic contact. Singletree soils have a mollic epipedon 15 to 20 inches thick. Techick soils have a sand and gravel discontinuity at 40 to 55 inches. Techicknot soils are 20 to 33 inches deep to the calcic horizon.
GEOGRAPHIC SETTING: Shenon soils are on fan terraces and have slopes of 1 to 20 percent. The soils formed in alluvium dominantly from extrusive igneous rocks. Elevations are 3,700 to 6,000 feet. The climate is cold and moist in winter and spring, and dry in summer. Average annual precipitation is 11 to 13 inches. Average annual temperature is 37 to 44 degrees F. Frost free period is 50 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cronks, Custco, Dacont, Dawtonia, Lacrol, Millhi, and Venum soils. Cronks and Venum soils are on foothills and mountains and have clayey-skeletal control sections. Venum soils have ochric epipedons. Dacont soils are on mountains and foothills and have loamy-skeletal control sections. Dawtonia soils are on fan terraces, foothills and mountains, have loamy-skeletal control sections, and have ochric epipedons. Custco soils are on mountains and have xeric moisture regimes. Lacrol and Millhi soils are on foothills and have fine-textured control sections. Millhi soils have ochric epipedons.
DRAINAGE AND PERMEABILITY: Well drained, slow to medium runoff, moderately slow permeability.
USE AND VEGETATION: Rangeland. Vegetation is mainly Wyoming big sagebrush and bluebunch wheatgrass.
DISTRIBUTION AND EXTENT: East-central Idaho. These soils are of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Lemhi County, Idaho, 1999.
REMARKS: Diagnostic features recognized in this pedon are:
Mollic epipedon - The zone from 0 to 9 inches (the A horizon and the Bt1 horizon).
Argillic horizon - The zone from 4 to 14 inches (Bt1 and Bt2 horizons). This is the particle-size control section.
Calcic horizon - The zone from 14 to 60 inches (Bk1, Bk2, Bk3, and Bk4 horizons).