LOCATION CHERPI IDInactive Series
TAXONOMIC CLASS: Ashy-skeletal, glassy Vitrandic Haplocryolls
TYPICAL PEDON: Cherpi gravelly loam, on a 50 percent west facing slope supporting a quaking aspen/serviceberry-mountain snowberry/pinegrass community type, woodland. Elevation is about 5,580 feet. (Colors are for dry soil unless otherwise noted.)
Oi--0 to 1 inch; forest litter - twigs, leaves and grass; abrupt smooth boundary.
A1--1 to 4 inches; dark brown (10YR 3/3)gravelly ashy loam, very dark brown (10YR 2/2) moist; moderate very fine granular structure; soft, very friable, nonsticky and nonplastic; many very fine and common fine through coarse roots; many very fine irregular pores; 20 percent pebbles; neutral (pH 6.6); abrupt smooth boundary. (3 to 11 inches thick)
A2--4 to 12 inches; brown (7.5YR 5/3) very gravelly ashy loam, dark brown (7.5YR 3/2) moist; moderate very fine granular structure; soft, very friable, slightly sticky and slightly plastic; common very fine through coarse roots; many very fine irregular pores; 20 percent pebbles, 10 percent cobbles and 10 percent stones; neutral (pH 6.6); clear wavy boundary. (0 to 8 inches thick)
Bw1--12 to 28 inches; light reddish brown (5YR 6/3) very gravelly ashy sandy loam, reddish brown (5YR 4/3) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and nonplastic; common very fine through coarse roots; common very fine tubular pores; 30 percent pebbles, 15 percent cobbles and 10 percent stones; neutral (pH 6.6); clear wavy boundary. (14 to 20 inches thick)
Bw2--28 to 45 inches; light reddish brown (5YR 6/3) very gravelly ashy sandy loam, reddish brown (5YR 4/3) moist; weak medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine and few fine and medium roots; common very fine tubular pores; 45 percent pebbles and 10 percent cobbles; slightly acid (pH 6.2); clear smooth boundary. (10 to 20 inches thick)
C--45 to 60 inches; light reddish brown (5YR 6/4) extremely gravelly sandy loam, yellowish red (5YR 4/6) moist; massive; soft, very friable, nonsticky and nonplastic; common very fine and few fine through coarse roots; many very fine irregular pores; 70 percent pebbles and 10 percent cobbles; slightly acid (pH 6.4).
TYPE LOCATION: Fremont County, Idaho; about 4 miles north of Ashton; about 300 feet east and 500 feet north of the southwest corner of section 6, T. 9 N., R 43 E.; Latitude - 44 degrees, 7 minutes, 50 seconds North; Longitude - 111 degrees, 23 minutes, 50 seconds West.
RANGE IN CHARACTERISTICS:
Average annual soil temperature - 38 to 43 degrees F.
Average summer soil temperature - 56 to 59 degrees F.
Mollic epipedon thickness - 10 to 16 inches
Solum thickness - 40 inches or more
Depth to bedrock - greater than 60 inches
Ammonium oxalate extractable aluminum plus 1/2 iron in the 0 to 30 inch zone - 0.05 to 0.4 percent
Volcanic glass content of the less than 2 mm fraction in the 0 to 30 inch zone - greater than 50 percent
Rock fragments in the particle-size control section, weighted average - 35 to 70 percent
A horizons:
Hue - 10YR or 7.5YR
Value - 3 to 5 dry, 2 or 3 moist
Chroma - 2 or 3 dry, 1 or 2 moist
Reaction - moderately acid or neutral
Bw horizons:
Hue - 10YR, 7.5YR or 5YR
Value - 4 to 6 dry, 3 to 5 moist
Chroma - 2 to 6 dry or moist
Texture - very gravelly ashy loam, very gravelly ashy sandy loam, extremely gravelly ashy sandy loam or extremely gravelly ashy loam
Pebbles - 25 to 60 percent
Cobbles - 5 to 20 percent
Stones - 0 to 10 percent
Reaction - moderately acid or neutral
C horizons:
Hue - 10YR, 7.5YR or 5YR
Value - 6 to 8 dry, 4 or 5 moist
Chroma - 3 to 6 dry or moist
Texture - extremely gravelly sandy loam, extremely cobbly sandy loam
Rock fragments - 60 to 90 percent
Reaction - moderately acid to slightly alkaline
Other - some pedons have C horizons consisting of cinders
COMPETING SERIES: This is the Nyman series. The Nyman soils have a paralithic contact at 20 to 40 inches. Lavacreek series in a closely related family has a loamy-skeletal particle-size control section.
GEOGRAPHIC SETTING: Cherpi soils formed in local alluvium or colluvium derived from loess, rhyolitic tuff, and cinders. They are on sideslopes of foothills, mountains and cinder cones. Slopes range from 6 to 60 percent. Elevations range from 5,200 to 7,100 feet. Average annual precipitation is 18 to 24 inches. Average annual air temperature is 36 to 41 degrees F. The frost free period is 50 to 70 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These include the Lag, Skyway, and Sadorus series. All three soils have less than 30 percent volcanic glass in the less than 2 mm fraction of the 0 to 30 inch zone. Skyway soils average less than 35 percent rock fragments in the particle-size control section and are 20 to 40 inches deep over hard bedrock. Sadorus soils are less than 20 inches to hard bedrock.
DRAINAGE AND PERMEABILITY: Well drained; slow runoff; moderately rapid permeability.
USE AND VEGETATION: Cherpi soils are used for woodland grazing, recreation, and wildlife habitat. These soils commonly support quaking aspen/serviceberry-mountain snowberry/pinegrass community type, woodland.
DISTRIBUTION AND EXTENT: Southeastern Idaho. The soils of this series are of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES PROPOSED: Targhee National Forest, Fremont County, Idaho, 1994. The name is coined.
REMARKS: This draft reflects a change in classification fron Ashy-skeletal,Vitrandic Cryoborolls to Ashy-skeletal, glassy Vitrandic Haplocryolls. This change is based on Soil Taxonomy 2nd Ed.
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from 1 to 12 inches (the A1 and A2 horizons).
Cambic horizon - The zone from 12 to 45 inches (the Bw1 and Bw2 horizons).
Particle-size control section - The zone from 10 to 40 inches (part of the A2, the Bw1 and part of the Bw2 horizons).