LOCATION ROCKYBROOK WAEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, isotic, frigid Andic Oxyaquic Dystrudepts
TYPICAL PEDON: Rockybrook very gravelly medial sandy loam - forestland, on a 38 slope with a southerly aspect at an elevation of 2,520 feet in a western hemlock/Pacific rhododendron-salal plant association. (When described on May 14, 1992, the soil was moist throughout. Colors are for moist soil unless otherwise stated. All textures are apparent field textures.)
Oi--0 to 1 inch; slightly decomposed needles, leaves, twigs, bark, and cone fragments; abrupt smooth boundary. (1 to 2.5 inches thick)
A--1 to 6 inches; dark yellowish brown (10YR 3/4) very gravelly medial sandy loam, brownish yellow (10YR 6/6) dry; weak very fine and fine granular structure; slightly hard, friable, nonsticky and nonplastic; weakly smeary; many very fine and fine and common medium and coarse roots; common very fine irregular pores; 50 percent gravel, 5 percent cobbles; strongly acid (pH 5.4); clear smooth boundary. (3 to 6 inches thick)
Bw1--6 to 20 inches; dark yellowish brown (10YR 3/6) extremely gravelly sandy loam, brownish yellow (10YR 6/6) dry; weak very fine and fine granular structure; slightly hard, friable, nonsticky and nonplastic; many very fine and fine and common medium and coarse roots; common very fine irregular pores; 55 percent gravel, 10 percent cobbles; strongly acid (pH 5.4); clear wavy boundary.
Bw2--20 to 26 inches; dark yellowish brown (10YR 4/6) extremely gravelly sandy loam, very pale brown (10YR 7/4) dry; weak very fine and fine granular and weak very fine subangular blocky structure; slightly hard, friable, nonsticky and nonplastic; many very fine and common fine, medium, and coarse roots; common very fine irregular pores; 55 percent gravel, 10 percent cobbles; moderately acid (pH 5.6); clear wavy boundary.
Bw3--26 to 32 inches; olive brown (2.5Y 4/4) extremely gravelly sandy loam, pale yellow (2.5Y 7/4) dry; weak very fine and fine subangular blocky and weak very fine and fine granular structure; slightly hard, friable, nonsticky and nonplastic; common very fine, fine, medium, and coarse roots; common very fine irregular pores; 60 percent gravel, 10 percent cobbles; moderately acid (pH 5.8); abrupt smooth boundary. (Combined thickness of the Bw horizon is 17 to 34 inches.)
Cd1--32 to 36 inches; olive brown (2.5Y 4/4) extremely gravelly loamy sand, pale yellow (2.5Y 7/3) dry; massive, hard, brittle, nonsticky and nonplastic; few very fine roots; few very fine irregular pores; slightly acid (pH 6.2); clear smooth boundary.
Cd2--36 to 61 inches; olive brown (2.5Y 4/4) extremely gravelly loamy sand, pale yellow (2.5Y 7/3 dry; massive; very hard, brittle, nonsticky and nonplastic; slightly acid (pH 6.2).
TYPE LOCATION: Clallam County, Washington, about 1 3/4 miles southwest of Cedar Flat, about 300 feet west and 1,770 feet south of the northeast corner of section 30, T. 28 N., R. 2 W. (Latitude 47 degrees, 53 minutes, 30 seconds N., Longitude 122 degrees, 58 minutes, 21 seconds W.)
RANGE IN CHARACTERISTICS: Mean annual soil temperature is 44 to 47 degrees F. These soils are usually moist, and are dry in the soil moisture control section for 30 to 45 consecutive days following the summer solstice. Depth to dense till is 20 to 40 inches. There is a perched water table above the dense fill substratum for over 30 cumulative days (Oxyaquic). The solum has an estimated moist bulk density of 0.90 to 1.00 g/cc and an acid-oxalate extractable aluminum plus one-half of the acid-oxalate extractable iron of 1 to 3 percent. The particle-size control section has 40 to 80 percent rock fragments by volume. Base saturation by ammonium acetate is 35 to 50 percent throughout the solum.
The A horizon has hue of 10YR or 7.5YR moist and dry, value of 5 or 6 dry, and chroma of 3 or 4 moist and 4 or 6 dry. It has 5 to 10 percent organic matter.
The Bw horizon has hue of 10YR, 7.5YR, or 2.5Y moist and dry, value of 3 or 4 moist and 5 through 7 dry, and chroma of 4 or 6 moist and dry. It is very gravelly sandy loam, extremely gravelly sandy loam, or very gravelly loam. It has 2 to 6 percent organic matter. It has 10 to 25 percent clay.
The Cd horizon has hue of 2.5Y or 10YR moist and dry, value of 5 or 7 dry, and chroma of 4 or 6 moist and 3, 4, or 6 dry. It is very gravelly loamy sand, extremely gravelly loamy sand, or very gravelly sandy loam. Reaction is slightly or moderately acid. Moist bulk density is 1.50 to 2.00 g/cc.
COMPETING SERIES: These are the Balsam, Dougan, Fernwood, Sarazan and Zygore series. The Balsam and Zygore series are very deep and have an umbric epipedon. Dougan and Fernwood soils are moderately deep to bedrock and have an umbric epipedon. Sarazan soils are deep to bedrock.
GEOGRAPHIC SETTING: Rockybrook soils are on glacial moraines. Slopes are 5 to 60 percent. The soils formed in continental glacial till. Elevations are 1,750 to 2,900 feet. Average annual precipitation is 35 to 65 inches. Average annual temperature is 42 to 45 degrees F. The frost-free season is 150 to 180 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Halfoss, Juandefuca, Pennycreek, Maidenpeak, Station, and Tunnelcreek soils. Halfoss and Tunnelcreek soils are on mountain slopes and are 20 to 40 inches to bedrock. Juandefuca and Maidenpeak soils are on mountain slopes and are very deep. Pennycreek soils are on mountain slopes and are 4 to 10 inches to bedrock. Station soils are on mountain slopes and are 10 to 20 inches to bedrock.
DRAINAGE AND PERMEABILITY: Moderately well drained; moderate permeability above the dense layer and slow permeabiliy in the dense glacial till. A seasonal water table is perched above the dense till from November through March.
USE AND VEGETATION: Timber production, wildlife habitat, recreation, and watershed. Native vegetation is Douglas-fir, western hemlock, western redcedar, Pacific rhododendron, salal, and Oregon-grape.
DISTRIBUTION AND EXTENT: Clallam and Jefferson Counties, Washington; MLRA 1. Series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Clallam County, Washington, 2000; Olympic National Forest.
REMARKS: Diagnostic horizons and features recognized in this pedon are the following:
Ochric epipedon
Cambic horizon - 6 to 32
Densic layer - 32 to 61 inches
Andic subgroup properties - 1 to 32 inches
PSCS - 11 to 32 inches
Soil moisture regime - udic
Oxyaquic subgroup criteria is met.
All depths to diagnostic horizons and other features are measured from the top of the first mineral horizon.