LOCATION THREEDOT IDEstablished Series
TAXONOMIC CLASS: Clayey-skeletal, smectitic Oxyaquic Argicryolls
TYPICAL PEDON: Threedot loam--on a 21 percent north by northeast-facing slope at an elevation of 7,000 feet on rangeland. (Colors are for dry soil unless otherwise stated. When described on July 7, 1982, the soil was moist throughout.)
A1--0 to 4 inches; very dark grayish brown (10YR 3/2) loam, black (10YR 2/1) moist; weak very fine and fine granular 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; 5 percent pebbles; slightly acid (pH 6.2); clear wavy boundary. (2 to 7 inches thick)
A2--4 to 8 inches; dark brown (10YR 3/3) loam, black (10YR 2/1) moist; weak very fine, fine and medium subangular blocky structure parting to weak very fine and fine granular; slightly hard, very friable, slightly sticky and slightly plastic; common very fine and few fine, medium and coarse roots; common very fine tubular and interstitial pores; 5 percent pebbles; slightly acid (pH 6.2); clear wavy boundary. (3 to 9 inches thick)
ABt--8 to 11 inches; brown (10YR 4/3) clay loam, very dark grayish brown (10YR 3/2) moist; weak very fine, fine and medium subangular blocky structure; slightly hard, very friable, sticky and slightly plastic; common very fine and few fine, medium and coarse roots; common very fine interstitial and few very fine tubular pores; common faint clay films lining pores and on faces of peds; 10 percent pebbles; slightly acid (pH 6.5); clear wavy boundary. (1 to 5 inches thick)
Bt/E--11 to 19 inches; B part is yellowish brown (10YR 5/4) gravelly clay loam, dark yellowish brown (10YR 4/4) moist, E part is dark yellowish brown (10YR 4/4), brown (10YR 4/3) moist; moderate very fine and fine subangular blocky structure; hard, friable, sticky and plastic; common very fine and few fine and medium roots; many very fine tubular pores; common faint clay films lining pores and on faces of peds; 30 percent pebbles; slightly acid (pH 6.4); clear wavy boundary. (4 to 10 inches thick)
Bt1--19 to 31 inches; strong brown (7.5YR 5/5) very gravelly clay, brown (7.5YR 4/4) moist; strong very fine, fine and medium subangular blocky structure; very hard, very firm, sticky and very plastic; common very fine roots; common very fine tubular pores; many distinct clay films lining pores and on faces of peds; 40 percent pebbles, 10 percent cobbles; slightly acid (pH 6.2); gradual wavy boundary. (7 to 18 inches thick)
Bt2--31 to 51 inches; strong brown (7.5YR 5/5) very gravelly clay, brown (7.5YR 4/4) moist; strong very fine, fine, medium and coarse subangular blocky structure; very hard, firm, sticky and very plastic; few very fine roots; common very fine tubular pores; many distinct clay films lining pores and on faces of peds; 40 percent pebbles, 15 percent cobbles; neutral (pH 6.7); clear wavy boundary. (13 to 30 inches thick)
2C--51 to 60 inches; brownish yellow (10YR 6/6) very gravelly loam, yellowish brown (10YR 5/8) moist; massive; slightly hard, very friable, slightly sticky and slightly plastic; few very fine roots; common very fine tubular pores; 30 percent pebbles, 10 percent cobbles; slightly effervescent; neutral (pH 7.2).
TYPE LOCATION: Lemhi County, Idaho; about 9 miles west of Leadore, Idaho; about 1,200 feet west and 1,600 feet north of the southeast corner of sec. 36, T. 16 N., R. 24 E.
Latitude - 44 degrees, 40 minutes, 14 seconds North; Longitude - 113 degrees, 32 minutes, 37 seconds West.
RANGE IN CHARACTERISTICS:
Average annual soil temperature - 37 to 40 degrees F.
Average summer soil temperature - 48 to 53 degrees F.
Mollic epipedon thickness - 10 to 14 inches
Depth to a perched water table - 1 to 2 feet April through June.
Control section - percent clay 40 to 60
Coarse fragments - 35 to 50 percent
A horizon
Chroma - 2 or 3 dry, 1 or 2 moist
AB horizon
Value - 3 through 5 dry, 2 or 3 moist
Chroma - 2 or 3, dry and moist
Texture - GR-L or CL
B/E horizon
Value - 4 through 7 dry, 4 or 5 moist
Chroma - 3 or 4, dry and moist
Texture - GR-CL or GRV-CL
Bt horizon
Hue - 7.5YR or 10YR
Value - 4 through 6 dry, 3 through 5 moist
Chroma - 3 through 6, dry or moist
Texture - GRV-C, CBV-C, GRX-C
2C horizon
Hue - 7.5YR or 10YR
Value - 6 or 7 dry, 5 or 6 moist
Chroma - 6 through 8, dry and moist
COMPETING SERIES: These are the Devoy, Dryn, Embargo, Home camp, Lemco, Passar, Redchief, Rooset, Spinlin, Tatiyee, Tellura and Wilpar soils. Devoy, Embargo, Home camp, Spinlin, and Wilpar soils are moderately deep to paralithic or lithic contact. Dryn soils have 12-15 inches precipitation. Lemco soils have O horizons and greater than 22 inches percipitation. Passar soils have coarse fragments greater than 10 inches in diameter in the control section. Dryn, Redchief, Rooset, and Tatiyee soils lack an E horizon. Redchief soils are strongly acid in the upper part of the argillic. Rooset soils have secondary carbonates at 10 to 48 inches depth. Tatiyee soils receive a dominance of precipitation in the spring and summer months. Tellura and Wilpar soils lack B/E or E/B horizons and are well drained.
GEOGRAPHIC SETTING: Threedot soils are on glacial moraines and mountains and have slopes of 5 to 50 percent. Elevations range from 6,500 to 8,500 feet. The soils formed in glacial till derived dominantly from quartzite. The climate is cold and moist in winter and cool and dry in summer. Average annual precipitation is 14 to 22 inches, and average annual temperature is 35 to 38 degrees. The frost-free period is 10 to 60 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Chamberlain, Geemore, Lemco, Parkay, Wiggleton, and Zeebar soils. Chamberlain soils are on fan terraces and average less than 35 percent clay in the control section. Geemore soils are on fan terraces and have a duripan at 20 to 40 inches depths. Lemco soils are on mountains and have an O horizon. Parkay and Zeebar soils are on mountains and have less than 35 percent clay in the control section. Wiggleton soils are on fan terraces and lack an argillic horizon.
DRAINAGE AND PERMEABILITY: Moderately well drained; runoff is medium; permeability is very slow.
USE AND VEGETATION: Rangeland. Vegetation is mainly Mountain big sagebrush and Idaho fescue.
DISTRIBUTION AND EXTENT: East-central Idaho. These soils are not extensive.
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 11 inches (A1, A2, and AB horizons).
Argillic horizon - the zone from 19 to 51 inches (Bt1 and Bt2 horizons).
The particle-size control section is the upper 20 inches of the argillic horizon.