LOCATION GRIMESCREEK IDEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, frigid Aquic Cumulic Haploxerolls
TYPICAL PEDON: Grimescreek sandy loam -- on a nearly level flood-plain step at 4,285 feet elevation in pastureland. When described on May 8, 2002, the soil was slightly moist to 11 inches, dry from 11 to 30 inches and wet below. (Colors are for air-dry soil unless otherwise noted.)
A1--0 to 6 inches; dark grayish brown (10YR 4/2) sandy loam, very dark brown (10YR 2/2) moist; moderate fine and medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine and fine, common medium roots; few very fine tubular, few fine and medium irregular pores; few fine and medium distinct dark yellowish brown (10YR 4/4) moist, relict Fe concentrations; 10 percent fine gravel; neutral (pH 6.8); clear smooth boundary.
A2--6 to 11 inches; grayish brown (10YR 5/2) sandy loam, very dark grayish brown (10YR 3/2) moist; weak fine and medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine and fine, few medium roots; few very fine and fine tubular and irregular pores; common fine and medium distinct dark yellowish brown (10YR 4/4) moist, relict Fe concentrations in pores; 10 percent fine gravel; neutral (pH 6.9); clear smooth boundary. (combined A horizon - 10 to 20 inches thick)
AC--11 to 21 inches; brown (10YR 5/3) sandy loam, dark brown (10YR 3/3) moist; massive; soft, very friable, nonsticky and nonplastic; few very fine, fine and medium roots; few very fine and fine tubular and irregular pores; common fine distinct dark yellowish brown (10YR 4/4) moist, relict Fe concentrations in pores; 5 percent fine gravel; neutral (pH 7.0); clear smooth boundary. (0 to 10 inches thick)
Ab1--21 to 23 inches; dark grayish brown (10YR 4/2) coarse sandy loam, very dark brown (10YR 2/2) moist; weak fine subangular blocky structure; soft, loose; nonsticky and nonplastic; few very fine roots; common very fine and fine irregular pores; few fine distinct dark yellowish brown (10YR 3/4) moist, Fe concentrations, 10 percent gravel; neutral (pH 7.0); clear discontinuous boundary.
Ab2--23 to 36 inches; brown (10YR 5/3) coarse sandy loam, dark brown (10YR 3/3) moist; weak fine subangular blocky structure; slightly hard, loose; nonsticky and nonplastic; common very fine, fine and medium irregular pores; many fine and medium distinct dark yellowish brown (10YR 4/4) moist, Fe concentrations, few fine and medium faint dark grayish brown (10YR 4/2) moist, depletions; 10 percent gravel; neutral (pH 6.8); clear smooth boundary. (combined Ab horizon - 2 to 18 inches thick)
ACb--36 to 58 inches; pale brown (10YR 6/3) fine gravelly sandy loam, brown (10YR 4/3) moist; massive; slightly hard, loose, nonsticky and nonplastic; common very fine and fine irregular pores; many fine prominent dark yellowish brown(10YR 4/4) and dark yellowish brown (10YR 4/6) moist, Fe concentrations, many medium and coarse faint dark grayish brown (10YR 4/2) moist, depletions; 15 percent fine gravel; slightly acid (pH 6.1); clear smooth boundary. (0 to 24 inches thick)
C--58 to 72 inches; light brownish gray (10YR 6/2) loamy sand, dark grayish brown (10YR 4/2) moist; single grain; loose, nonsticky and nonplastic; dark gray (2.5Y 4/1) moist reduced matrix; 5 percent fine gravel; slightly acid (pH 6.4).
TYPE LOCATION: Boise County, Idaho; about 3 miles southwest of Placerville; 1,150 feet south and 1,150 feet east of the northwest corner of section 34, T.7 N., R.4 E.; USGS Placerville Quadrangle; Latitude - 43 degrees, 54 minutes, 20 seconds N. and Longitude - 115 degrees, 58 minutes, 29 seconds W.; NAD 83.
RANGE IN CHARACTERISTICS:
Thickness of mollic epipedon - 20 to 40 inches
Depth to redoximorphic features - 20 to 30 inches
Depth to bedrock - 60 inches or more
Reaction - slightly acid or neutral
Particle-size control section - 5 to 18 percent clay; 0 to 15 percent rock fragments
Moisture control section - dry 45 to 75 consecutive days following the summer solstice
Average annual soil temperature - 44 to 47 degrees F.
A horizon
Value - 4 or 5 dry, 2 or 3 moist
Chroma - 1 through 3 dry or moist
Clay content - 8 to 18 percent
Rock fragments - 0 to 15 percent gravel
Relict redoximorphic features do not occur in some pedons
Ab horizon
Value - 4 or 5 dry, 2 or 3 moist
Chroma - 1 through 3 dry or moist
Texture - COSL, SL or LFS
Clay content - 4 to 18 percent
Rock fragments - 0 to 15 percent gravel
Redoximorphic features - few to many, distinct or prominent Fe concentrations; none through common faint depletions
Redoximorphic features are relict in some pedons
C horizon
Value - 5 or 6 dry, 3 or 4 moist
Chroma - 1 through 3 dry or moist
Texture - SL, LS, LFS or S
Clay content - 0 to 8 percent
Rock fragments - 0 to 15 percent gravel
Redoximorphic features - none to common, faint or distinct Fe concentrations; reduced matrix is gleyed in some pedons
Thin discontinuous lenses of sandy and/or loamy material with variable organic matter content occur in most pedons.
COMPETING SERIES: There are no competing series. Cheval soils are similar, but have a lithologic discontinuity above 40 inches and a coarse-loamy over sandy or sandy-skeletal particle-size class.
GEOGRAPHIC SETTING: Grimescreek soils are on flood plains at elevations of 3,400 to 4,650 feet. Slopes range from 0 to 2 percent. These soils formed in mixed alluvium from igneous rocks (dominantly granodiorite) and fine pyroclastic materials. The average annual precipitation is 22 to 28 inches. The average annual temperature is 42 to 45 degrees F. The frost-free period is 60 to 90 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Brassey, Middlefork and Pioneervil soils. These are woodland soils. Brassey soils are well drained, loamy-skeletal and occur on alluvial fan remnants. Middlefork soils are well drained, have fine-loamy argillic horizons and occur on alluvial fan remnants. Pioneervil soils are moderately well drained, do not have pachic epipedons and occur on adjacent higher flood-plain steps.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained with a high water table at 20 and 30 inches below the surface at some time during April and May; very slow runoff; moderately rapid permeability. Grimescreek soils are subject to occasional flooding for brief periods in December through June.
USE AND VEGETATION: Grimescreek soils are used mainly for wildlife habitat and mountain semi-wet meadow pasture. Native vegetation is slender wheatgrass and mountain brome.
DISTRIBUTION AND EXTENT: West-central Idaho. MLRA 44. Grimescreek soils are of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Boise County Area, Idaho, Parts of Ada and Boise Counties, 2005.
REMARKS: Diagnostic horizons and features recognized in this pedon:
Mollic epipedon with irregular decrease in organic carbon - zone from 0 to 36 inches (A1, A2, AC, Ab1 and Ab2 horizons)
Redoximorphic features (current conditions) - zone from 23 to 60 inches (Ab2, ACb and C horizons)
Particle-size control section - zone from 10 to 40 inches
Soil moisture regime - xeric