LOCATION BUCKPEAK WAEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, mesic Xeric Palehumults
TYPICAL PEDON: Buckpeak silt loam-forest, on a 30 percent southeast- facing convex slope at an elevation of 660 feet. The soil was moist when described. (Colors are for moist soil unless otherwise stated.)
Oe--1 inch to 0; partially decomposed needles, twigs and bark.
Ac--0 to 8 inches; very dark grayish brown (10YR 3/2) silt loam, grayish brown (10YR 5/2) dry; weak fine and medium granular structure; slightly hard, friable, slightly sticky and slightly plastic; many fine and medium and common coarse roots; 10 percent 2 to 5 mm shot-like concretions; medium acid (pH 5.8); clear wavy boundary. (6 to 9 inches thick)
AB--8 to 19 inches; dark brown (10YR 3/3) silt loam, brown (10YR 5/3) dry; weak fine subangular blocky structure parting to fine and very fine granular; hard, friable, slightly sticky and plastic; common fine, medium and coarse roots; common fine tubular pores; 5 percent soft pebble-size siltstone fragments; strongly acid (pH 5.6); clear wavy boundary. (8 to 12 inches thick)
Bt1--19 to 31 inches; dark brown (7.5YR 4/4) silty clay loam, light brown (7.5YR 6/4) dry; weak fine and medium subangular blocky structure; hard, firm, sticky and plastic; few fine, medium and coarse roots; common fine and very fine tubular pores; common faint patchy clay films on faces of peds; 30 percent soft pebble-size siltstone fragments; strongly acid (pH 5.5); clear wavy boundary. (8 to 14 inches thick)
Bt2--31 to 44 inches; dark brown (7.5YR 4/4) silty clay loam, light brown (7.5YR 6/4) dry; weak medium subangular blocky structure; hard, firm, sticky and plastic; few fine medium and coarse roots; common fine and very fine tubular pores; many discontinuous faint clay films on faces of peds; 50 percent soft pebble-size siltstone fragments; strongly acid (pH 5.1); abrupt irregular boundary. (10 to 16 inches thick)
BCt--44 to 60 inches; dark brown (7.5YR 4/4) silty clay loam, light brown (7.5YR 6/4) dry; massive; hard, firm, sticky and plastic; few coarse roots; common fine and very fine tubular pores; continuous prominent clay films in vertical cracks and on faces of rock fragments; 75 percent soft pebble-size siltstone fragments; very strongly acid (pH 5.0).
TYPE LOCATION: Lewis County, Washington; about 2 miles southeast of Pe E11, 400 feet south and 50 feet east of the northwest corner of 12 N., R. 5W., W.M.
RANGE IN CHARACTERISTICS: These soils are usually moist, but are dry in the moisture control section for 45 to 60 consecutive days following summer solstice in most years. Average annual soil temperature ranges from 49 degrees to 54 degrees F. Soft siltstone and sandstone fragments average 35 to 60 percent in the particle-size control section. The particle-size control section is 20 to 35 percent clay.
The A & AB horizons have hue of 10YR or 7.5YR, value of 2 or 3 moist and 4 or 5 dry; and chroma of 2 or 3 moist or dry.
The Bt horizon has hue of 7.5YR or 10YR, value of 3 or 4 moist and 5 or 6 dry; and chroma of 3 through 5 moist and 4 through 6 dry. It is silt loam, silty clay loam or loam. Soft siltstone and sandstone fragments range from 25 to 60 percent.
The BCt horizon has 40 to 85 percent soft siltstone and sandstone fragments. It is silty clay loam, clay loam, or loam. This horizon is very strongly acid or strongly acid.
COMPETING SERIES: This is the Centralia series. Centralia soils lack weathered rock fragments in the argillic horizon.
GEOGRAPHIC SETTING: Buckpeak soils are on uplands at elevations of 200 to 1,800 feet. Slopes range from 8 to 90 percent. They formed in colluvium and residuum from siltstone, shale and fine-grained sandstone. Average annual temperature is 47 degrees to 52 degrees F. Annual precipitation ranges from 40 to 75 inches. Growing season (28 degrees F) is 150 to 240 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Galvin, Germany, Melbourne, Olympic, Raught, Thrash, Vader, and Walville soils. Galvin soils are fine-silty. Melbourne and Olympic soils are fine. Germany and Raught soils have a udic moisture regime. Thrash and Walville soils are medial. Vader soils are coarse-loamy and have a cambic horizon.
DRAINAGE AND PERMEABILITY: Well drained; medium or rapid runoff; moderate permeability.
USE AND VEGETATION: Used for timber production, wildlife habitat and watershed. Vegetation is Douglas-fir, western hemlock, western redcedar, bigleaf maple, and red alder, with an understory of vine maple, western swordfern , Oregongrape, red huckleberry, salal, longtube twinflower, trailing blackberry, western rattlesnake plantain, violet, and western brackenfern.
DISTRIBUTION AND EXTENT: Southwestern Washington. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Grays Harbor County, Washington, 1979.
REMARKS: Diagnostic horizons and features recognized in this pedon are an umbric epipedon from the mineral surface to 19 inches and an argillic horizon from 19 to 60 inches. The classification change is based on laboratory data on the associated Centralia series (Sample Number S84WA- 015-005) and the re-establishment of Palehumults in Soil Taxonomy Handbook, Issue No.12.