LOCATION LAVACREEK IDEstablished Series
TAXONOMIC CLASS: Medial-skeletal, amorphic Humic Xeric Vitricryands
TYPICAL PEDON: Lavacreek very gravelly medial silt loam on a 54 percent north-facing slope at an elevation of 6,000 feet in rangeland. When described on June 26, 1979, the pedon was moist below 36 inches. (Colors are for dry soil unless otherwise noted).
A1--0 to 4 inches; dark brown (10YR 3/3) very gravelly medial silt loam, very dark brown (10YR 3/2) moist; weak fine granular structure; soft, very friable; many very fine, fine, medium and coarse roots; many very fine interstitial pores; about 35 percent pebbles; neutral (pH 6.6); clear wavy boundary. (2 to 6 inches thick)
A2--4 to 23 inches; brown (10YR 4/3) very gravelly medial silt loam, dark brown (10YR 3/3) moist; weak fine granular structure; soft, very friable; many very fine, fine medium and coarse roots; many very fine interstitial pores; about 40 percent pebbles; neutral (pH 6.6); gradual wavy boundary. (6 to 19 inches thick)
Bw1--23 to 36 inches; dark yellowish brown (10YR 4/4) very cobbly medial loam, dark yellowish brown (10YR 3/4) moist; weak fine subangular blocky structure; soft, very friable; many very fine, fine, medium and coarse roots; many very fine interstitial pores; about 30 percent cobbles and 25 percent pebbles; neutral (pH 6.8); gradual wavy boundary. (0 to 13 inches thick)
Bw2--36 to 41 inches; yellowish brown (10YR 5/4) extremely cobbly medial loam, dark yellowish brown (10YR 4/4) moist; weak fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common very fine, fine and medium roots; many very fine tubular pores; about 35 percent cobbles and 30 percent pebbles; few discontinuous bleached sand and silt grains on faces of peds; neutral (pH 6.8); clear wavy boundary. (5 to 22 inches thick)
2C--41 to 49 inches; very pale brown (10YR 7/3) extremely cobbly sandy loam, yellowish brown (10YR 5/4) moist; weak fine subangular blocky structure; soft, very friable; few very fine roots; many very fine tubular pores; about 40 percent cobbles and 30 percent pebbles; neutral (pH 6.8); diffuse irregular boundary. (0 to 10 inches thick)
2R--49 inches; fractured quartzite bedrock with less than 5 percent C material in fractures.
TYPE LOCATION: Blaine County, Idaho about 4 miles north and 1 mile east of Lavalake Ranch; 2,500 feet north and 800 feet east of the southwest corner of section 2, T. 1 N R. 23 E. Latitude 43 degrees, 26 minutes, 55 seconds North; Longitude 113 degrees, 41 minutes, 28 seconds West.
RANGE IN CHARACTERISTICS:
The soil moixture control section is dry for 60 to 90 consecutive days.
Depth to quartzite bedrock - more than 40 inches
Solum thickness - 32 to 41 inches
Average annual soil temperature - 37 to 43 degrees F.
Average summer soil temperature - 54 to 59 degrees F.
Reaction - Neutral to moderately acid throughout
Thickness of mollic epipedon - 10 to 23 inches
Bulk density (at 1/3 bar water tension) - 0.95 g/cm or less in the upper 30 inches.
Phosphate retention - 50 to 80 percent
Glass - 5 to 30 percent
15 bar water, dry - 12 to 15 percent
15 bar water, moist - 20 to 30 percent
Acid-oxalate aluminum plus one-half the iron - 1.0 to 2.0
A Horizon
Value, dry - 3 through 5, moist - 2 or 3
Chroma, moist or dry - 2 through 4
Bw Horizon
Hue - 10YR or 7.5YR
Value, dry - 4 through 6, moist - 3 or 4
Chroma, moist or dry - 3 or 4
Texture - GRV-SIL, CBV-L, CBX-L, GRV-L
Field estimated clay content - 10 to 20 percent
Rock fragments - 35 to 65 percent
2C Horizon
Value, dry - 6 or 7, moist - 3 to 5
Chroma, moist or dry - 3 or 4
Texture - GRV-L, GRX-L, CBX-SL
Field estimated clay content - 10 to 20 percent
Rock fragments - 35 to 80 percent
COMPETING SERIES: This is the Sky series. Sky soils are moderately deep to a paralithic contact.
GEOGRAPHIC SETTING: Lavacreek soils are on steep mountainsides. Slopes range from 6 to 60 percent. Elevation ranges from 5,200 to 9,300 feet. The soil formed in a mantle of volcanic ash over colluvium. The average annual precipitation is 16 to 24 inches, most of which falls as snow or early fall or late spring rains. The average annual temperature is 36 to 41 degrees F. The frost-free season is 30 to 70 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Blackspar, Drage, Dollarhide, Grassycone, Ketchum, Milligan, Povey, and Vitale series. Blackspar soils are lithic and lack a mollic epipedon and occur on south and west-facing mountainsides. Dollarhide soils are lithic and occur on ridgetops and convex north and east-facing mountainsides. Drage soils have a Bk horizon and occur on fan terraces. Grassycone soils are medial-skeletal. Ketchum soils lack a mollic epipedon and occur on steep timbered north and east-facing mountainsides. Milligan and Vitale soils are moderately deep and occur on south and west-facing mountainsides. Povey soils are pachic and lack the influence of volcanic ash and occur on north and east-facing mountainsides.
DRAINAGE AND PERMEABILITY: Well drained. Medium to very rapid runoff. Permeability is moderate.
USE AND VEGETATION: Mainly used for rangeland. Vegetation is Idaho fescue, mountain big sagebrush, lupine, arrowleaf balsamroot.
DISTRIBUTION AND EXTENT: Lavacreek soils are of small extent in south central Idaho.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Blaine County, Idaho, 1985.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - the zone from the surface of the soil to approximately 23 inches.
Cambic horizon - the zone from 23 to 41 inches.
Thickness of Andic properties - zone form the soil surface to 41 inches (A1, A2, Bw1 and Bw2 horizons). Properties based on reference samples from associated Huddle series.
Particle size control section - zone from the surface to 40 inches (A1, A2, Bw1, and Bw2 horizons)
A BC horizon is present in some pedons.
The 5/2010 description reflects a reclassification from Xeric to Humic Xeric subgroup.