LOCATION BRASSEY IDEstablished Series
The Brassey series consists of very deep, well drained soils with moderate permeability that formed in volcaniclastic sediments and alluvium from igneous rocks. Slopes range from 3 to 15 percent in intermontane basins. The average annual precipitation is about 25 inches and the average annual temperature is about 44 degrees F.
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Ultic Argixerolls
TYPICAL PEDON: Brassey gravelly loam, forested -- on a 5 percent concave southeast-facing slope at 4,360 feet elevation. When described on August 2, 2001, the soil was dry throughout. (Colors are for air-dry soil unless otherwise noted.)
Oi--0 to 1 inch; slightly decomposed forest litter.
A1--1 to 4 inches; grayish brown (10YR 5/2) gravelly loam, very dark grayish brown (10YR 3/2) moist; moderate fine subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; many very fine and fine, common medium, few coarse roots; many very fine and fine, few medium irregular pores; 15 percent gravel; slightly acid (pH 6.1); clear smooth boundary.
A2--4 to 11 inches; brown (10YR 5/3) gravelly loam, dark brown (10YR 3/3) moist; moderate fine subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine and fine, common medium, few coarse roots; common very fine and fine, few medium irregular pores; 15 percent gravel; moderately acid (pH 5.8); clear wavy boundary. (combined A horizon -10 to 14 inches thick)
Bt1--11 to 21 inches; yellowish brown (10YR 5/4) very gravelly loam, dark yellowish brown (10YR 3/4) moist; moderate fine and medium subangular blocky structure; slightly hard, friable, moderately sticky and moderately plastic; common very fine, fine and medium, few coarse roots; few very fine and fine tubular pores; common faint clay films on faces of peds, rock fragments and in pores; 40 percent gravel and 10 percent cobbles; 10 percent pararock fragments; moderately acid (pH 5.6); clear wavy boundary. (4 to 10 inches thick)
Bt2--21 to 37 inches; yellowish brown (10YR 5/4) very gravelly sandy clay loam, dark yellowish brown (10YR 3/4) moist; moderate fine and medium subangular blocky structure; hard, friable, moderately sticky and moderately plastic; common very fine, fine and medium, few coarse roots; few very fine and fine tubular pores; many faint clay films on faces of peds, rock fragments and in pores; 45 percent gravel and 10 percent cobbles; 15 percent pararock fragments; moderately acid (pH 5.6); clear wavy boundary. (8 to 20 inches thick)
Bt3--37 to 49 inches; light yellowish brown (10YR 6/4) extremely gravelly sandy loam, dark yellowish brown (10YR 4/4) moist; moderate fine and medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; few very fine, fine and medium roots; few very fine and fine tubular pores; many faint clay films on faces of peds, rock fragments and in pores; 45 percent gravel and 15 percent cobbles; 15 percent pararock fragments; moderately acid (pH 5.7); clear wavy boundary. (6 to 18 inches thick)
C--49 to 60 inches; light yellowish brown (10YR 6/4) extremely gravelly coarse sand, dark yellowish brown (10YR 4/4) moist; single grain; loose, nonsticky and nonplastic; few very fine and fine roots; few very fine, fine and medium irregular pores; 65 percent gravel; 5 percent pararock fragments; moderately acid (pH 6.0).
TYPE LOCATION: Boise County, Idaho; about 2 miles southwest of Placerville; 1,250 feet north and 50 feet east of the southwest corner of section 22, T.7 N., R.4 E.; USGS Placerville Quadrangle; Latitude - 43 degrees, 55 minutes, 35 seconds N. and Longitude - 115 degrees, 58 minutes, 48 seconds W.; NAD 83.
RANGE IN CHARACTERISTICS:
Thickness of mollic epipedon - 10 to 20 inches
Depth to base of argillic horizon - 30 to 50 inches
Depth to bedrock - 60 inches or more
Base saturation - 50 to 75 percent in some part between 10 and 30 inches
Reaction - moderately acid or slightly acid
Particle-size control section - 18 to 27 percent clay; 35 to 60 percent rock fragments
Moisture control section - dry 60 to 75 consecutive days following the summer solstice
Average annual soil temperature - 44 to 47 degrees F.
A horizon
Hue - 7.5YR or 10YR
Chroma - 2 or 3 dry or moist
Rock fragments - 15 to 25 percent gravel
Bt1 horizon
Hue - 7.5YR or 10YR
Chroma - 3 or 4 dry or moist
Texture - L
Clay content - 20 to 27 percent
Rock fragments - 15 to 50 percent gravel, 0 to 10 percent cobble and 15 to 50 percent total
Pararock fragments - 0 to 15 percent
Bt2 horizon
Hue - 7.5YR or 10YR
Value - 5 or 6 dry, 3 or 4 moist
Texture - L or SCL
Clay content - 20 to 27 percent
Rock fragments - 25 to 60 percent gravel, 0 to 10 percent cobbles, 0 to 5 percent stones and 35 to 70 percent total
Pararock fragments - 0 to 15 percent
Bt3 horizon
Hue - 7.5YR or 10YR
Value - 6 or 7 dry, 4 or 5 moist
Chroma - 4 through 6 dry or moist
Texture - SL, COSL or SCL
Clay content - 18 to 24 percent
Rock fragments - 35 to 60 gravel, 0 to 20 percent cobbles, 0 to 10 percent stones and 45 to 75 percent total
Pararock fragments - 0 to 15 percent
C horizon
Hue - 7.5YR or 10YR
Value - 6 or 7 dry, 4 or 5 moist
Chroma - 4 through 6 dry or moist
Texture - LS, LCOS, S or COS
Clay content - 2 to 7 percent
Rock fragments - 35 to 70 percent gravel, 0 to 20 percent cobbles, 0 to 10 percent stones and 60 to 85 percent total
Pararock fragments - 0 to 25 percent
COMPETING SERIES: These are the Apmat, Durst, Fergie, Fraval, Henhoit, Little Wood, Morningstar, Mulshoe, Sapkin and Sattley series. Apmat soils have 10 to 18 percent clay in the argillic horizon. Durst, Fraval, Mulshoe and Sapkin soils have a lithic or paralithic contact at depths of 20 to 40 inches. Fergie soils have bedrock at 40 to 60 inches and are dry 90 to 120 days. Henhoit soils are deeper than 50 inches to the base of the argillic horizon and have hue of 2.5YR to 7.5YR. Little Wood soils do not have an O horizon, are dry for more than 75 consecutive days (12 to 18 inches annual precipitation) and are 21 to 34 inches deep to the sandy-skeletal substratum and base of argillic horizon. Morningstar have 25 to 35 percent clay in the argillic horizon and do not have sandy-skeletal substratum. Sattley soils are 40 to 60 inches deep to bedrock and are dry about 105 consecutive days during summer and fall.
GEOGRAPHIC SETTING: Brassey soils are on alluvial fan remnants at elevations of 4,050 to 5,100 feet. These soils formed in volcaniclastic sediments and alluvium from igneous rocks. Slopes range from 3 to 15 percent. Average annual precipitation is 24 to 28 inches. Average annual temperature is 42 to 45 degrees F. Frost-free period is 60 to 90 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Middlefork soils which are fine-loamy and occur on similar geomorphic positions.
DRAINAGE AND PERMEABILITY: Well drained; slow runoff; moderate permeability.
USE AND VEGETATION: Brassey soils are used mainly for timber production and woodland grazing. Some areas are used for homesites. Native vegetation is Douglas-fir, ponderosa pine and common snowberry.
DISTRIBUTION AND EXTENT: West-central Idaho. MLRA 44. Brassey 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 - zone from 1 to 11 inches (A1 and A2 horizons)
Argillic horizon - zone from 11 to 49 inches (Bt1, Bt2 and Bt3 horizons)
Particle-size control section - zone from 11 to 31 inches
Soil moisture regime xeric
All depths related to diagnostic horizons and features listed in the range of characteristics are measured from the top of the first mineral horizon.