LOCATION CASTLEPEAK IDEstablished Series
TAXONOMIC CLASS: Sandy-skeletal, mixed Typic Cryorthents
TYPICAL PEDON: Castlepeak very gravelly sandy loam--on a 1 percent north-facing slope in rangeland at 7,000 feet elevation. (Colors are for dry soil unless otherwise noted. When described on July 17, 1985, the soil was dry throughout.)
A--0 to 2 inches; brown (10YR 4/3) very gravelly sandy loam, dark brown (10YR 3/3) moist; weak fine granular structure; soft, very friable, nonsticky and nonplastic; many very fine and fine and few medium roots; many very fine and fine interstitial pores; 50 percent pebbles; strongly acid (pH 5.4); abrupt smooth boundary. ( 1 to 4 inches thick)
Bw--2 to 7 inches; yellowish brown (10YR 5/4) very gravelly loamy sand, brown (7.5YR 4/4) moist; weak fine subangular blocky structure parting to weak fine granular; soft, very friable, nonsticky and nonplastic; many very fine and fine and few medium roots; many very fine and fine interstitial pores; 45 percent pebbles; strongly acid (pH 5.4); clear smooth boundary. (4 to 6 inches thick)
BC--7 to 13 inches; yellowish brown (10YR 5/6) extremely gravelly loamy sand, dark yellowish brown (10YR 4/6) moist; single grain; loose; common very fine and fine roots; many very fine and fine interstitial pores; 65 percent pebbles; strongly acid (pH 5.4); gradual smooth boundary. (5 to 15 inches thick)
C1--13 to 19 inches; light yellowish brown (10YR 6/4) extremely gravelly loamy sand, yellowish brown (10YR 5/4) moist; single grain; loose; few very fine and fine roots; many fine interstitial pores ; 70 percent pebbles, 5 percent stones; moderately acid (pH 5.6); gradual wavy boundary. (5 to 20 inches thick)
C2--19 to 60 inches; light gray (10YR 7/2) extremely gravelly coarse sand, light brownish gray (10YR 6/2) moist; single grain; loose; few fine roots; many fine and medium interstitial pores; 55 percent pebbles, 15 percent cobbles, 5 percent stones; moderately acid (pH 5.6).
TYPE LOCATION: Blaine County, Idaho; about 2.5 miles northeast of Alturas Lake, about 2,500 feet south and 1,500 feet east from the northwest corner of section 4, T. 7 N., R. 14 E.
RANGE IN CHARACTERISTICS:
Average annual soil temperature - 34 to 39 degrees F.
Average summer soil temperature - 44 to 49 degrees F.
Control section - Percent clay: 0 to 5.
Rock fragments: 60 to 90 percent.
A horizon
Value - 3 through 5 dry or moist.
Chroma - 3 or 4 dry or moist.
Coarse fragments - 35 to 55 percent
Reaction - strongly or moderately acid
Bw horizon
Hue - 10YR or 7.5YR.
Value - 4 through 6 dry or moist.
Clay content - 2 to 8 percent.
Coarse fragments - 40 to 55 percent.
Reaction - strongly acid or moderately acid.
BC and C horizon
Hue - 10YR or 7.5YR.
Value - 5 through 7 dry and 4 through 6 moist.
Chroma - 2 through 4 dry or moist.
Texture - GRX-LCOS, GRX-COS, CBX-COS, GRX-LS.
Rock fragments - 65 to 90 percent with at least 5 percent stones. Reaction - moderately acid or strongly acid.
COMPETING SERIES: These are the Alflack, Canlodore, Chena, Cryomont (T), Graylock, Nataga, Nizina, Obscurity, Pirapeak, Ragamuffin, Stecum, and Studebaker series. Alflack and Stecum soils are moderately deep. Chena soils have an O horizon, lack a B horizon and lack stones in the C horizon. Chenega soils have an O horizon and lack a B horizon. Cryomont soils have an O horizon and are slightly acid or neutral. Graylock soils have 35 to 60 percent coarse fragments in the control section. Howardsville soils lack Bw horizons and the precipitation is evenly distributed throughout the year. Mirror Lake soils have an O horizon and average summer soil temperature higher than 49 degrees F. Nataga soils have an O horizon and lack stones in the C horizon. Nizina soils have an average annual temperature of 23 to 27 degrees F. Obscurity soils have 15 to 50 percent volcanic glass and glass aggregates in the control section. Polepatch soils have an O horizon, have boulders on the surface and have 10 to 40 percent volcanic glass in the particle-size control section. Studebaker soils have 15 to 50 percent volcanic glass and glass aggregates in the control section.
GEOGRAPHIC SETTING: Castlepeak soils are on outwash fans, fan terraces and stream terraces. These soils formed in glacial outwash and alluvium. Slopes are 1 to 6 percent and elevations are 6,300 feet to 7,500 feet. The climate is cold and moist in winter and spring and cool and dry in summer. Average annual precipitation is 12 to 16 inches. Average annual temperature is 33 to 38 degrees F. Frost-free period is 5 to 30 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Busterback, Langer, Struggle, and Yankeefork soils. Busterback soils are on stream terraces and outwash fans, have mollic epipedons and have loamy-skeletal particle-size control sections. Langer soils are on mountains and have mollic epipedons. Struggle soils are on moraines, and have cambic horizons. Yankeefork soils are on outwash fans, fan terraces and stream terraces, have cambic horizons and loamy-skeletal particle-size control sections.
DRAINAGE AND PERMEABILITY: Excessively drained. Slow runoff. Very rapid permeability.
USE AND VEGETATION: Dominantly used for rangeland although minor areas are used for irrigated pasture. The natural vegetation is low sagebrush and Idaho fescue.
DISTRIBUTION AND EXTENT: Central Idaho. These soils are not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Custer-Lemhi Counties, Idaho, 1999.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from 0 to 7 inches (A and Bw
horizons).
Particle-size control section - The zone from 10 to 40 inches (part of the BC, C1 and part of C2 horizons.)
Xeric Moisture Regime