LOCATION HOFFSTADT WAEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, isotic, frigid Andic Dystrudepts
TYPICAL PEDON: Hoffstadt very gravelly sandy loam - under a coniferous forest on a 58 percent irregular south-facing upper back slope at an elevation of 2,160 feet. (The soil was moist when described. Colors are for moist soil unless other wise stated. All textures are apparent field textures.)
Oe--2 inches to 0; loose, partially decomposed organic litter composed of needles, leaves, twigs, cones and bark chips; abrupt smooth boundary. (1 to 4 inches thick)
A--0 to 4 inches; very dark grayish brown (10YR 3/2) very gravelly sandy loam, grayish brown (10YR 5/2) dry; weak very fine granular and subangular blocky structure; soft, very friable, slightly sticky and nonplastic and weakly smeary; intermittent dark grayish brown (10YR 4/2) sandy loam, light grayish brown (10YR 6/2) dry 1/4 to 1 inch thick at surface of horizon; many very fine, fine medium and common coarse roots; many fine pores; 30 percent angular and subangular pebbles and 10 percent cobbles; moderately acid (pH 5.8); clear wavy boundary. (3 to 6 inches thick)
Bw1--4 to 10 inches; dark yellowish brown (10YR 4/4) very gravelly sandy loam, light yellowish brown (10YR 6/4) dry; weak very fine and fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic and weakly smeary; many very fine, fine, medium and common coarse roots; many fine pores; 30 percent angular and subangular pebbles and 10 percent cobbles; slightly acid (pH 6.2); clear wavy boundary.
Bw2--10 to 19 inches; dark yellowish brown (10YR 4/6) very cobbly sandy loam, light yellowish brown (10YR 6/4) dry; weak fine subangular blocky structure; soft, very friable, slightly sticky and nonplastic and weakly smeary; many very fine, fine medium and common coarse roots; many fine pores; 25 percent angular and subangular pebbles and 25 percent cobbles; slightly acid (pH 6.2); clear wavy boundary. (Combined thickness of the Bw horizon is 14 to 22 inches)
BC--19 to 47 inches; brown (7.5YR 4/4) extremely stony sandy loam, pale brown (10YR 6/3) dry; weak fine subangular blocky structure; soft, very friable, slightly sticky and nonplastic and weakly smeary; common very fine, fine, medium and coarse roots; common fine pores; 5 percent angular and subangular pebbles, 5 percent cobbles and 65 percent 10 to 24 inch angular stones; moderately acid (pH 6.0); abrupt irregular boundary. (20 to 30 inches thick)
2R--47 inches; fractured hard olivine basalt.
TYPE LOCATION: Cowlitz County, Washington; on a mountain slope adjacent to the North Fork of the Toutle River below the summit of Elk Rock; 150 feet south and 880 feet east of northwest corner, section 7, T. 9 N., R. 4 E., W.M.
RANGE IN CHARACTERISTICS: Average annual soil temperature at a depth of 20 inches ranges from 44 to 46 degrees F. Depth to bedrock ranges from 40 to 60 inches. Unweathered igneous rock fragments average from 50 to 80 percent in the particle-size control section and include angular and subangular pebbles, cobbles and stones. Reaction is moderately acid or slightly acid throughout. Some profiles have a small admixture of pumice fragments in the upper part.
The A horizon has hue of 10YR or 7.5YR, value of 2 through 4 moist, 4 or 5 dry, and chroma of 2 or 3 moist and dry. It has 25 to 35 percent pebbles and 10 to 15 percent cobbles.
The Bw horizon has hue of 10YR, 7.5YR or 5YR, value of 3 to 5 moist, 4 to 7 dry, and chroma of 4 to 6 moist and dry. It is very gravelly, very stony, extremely cobbly, extremely stony, or very cobbly sandy loam and has 20 to 35 percent unweathered pebbles, 10 to 30 percent cobbles, and 0 to 50 percent stones.
The BC and C horizons have hue of 10YR or 7.5YR, value of 4 or 5 moist, 5 to 7 dry, and chroma of 3 to 6 moist and dry. It has 5 to 30 percent pebbles, 5 to 15 percent cobbles, and 40 to 70 percent stones.
COMPETING SERIES: These are the Backroad, Marblecreek, Pearsoncreek, and Sarazan series. Backroad, Marblecreek, Pearsoncreek soils are more than 60 inches deep to bedrock. Sarazan soils are silt loam or silty clay loam and 35 to 55 percent hard rock fragments in the particle-size control section.
GEOGRAPHIC SETTING: Hoffstadt soils are on mountain slopes, benches, and ridgetops at elevations of 1,800 to 2,800 feet. Slopes are 2 to 90 percent. These soils formed in colluvium from basic igneous rock including porphoritic andesite, olivine basalt and andesitic alloclastic breccia with a mantle of aerially deposited volcanic ash. Some Hoffstadt soils have a small admixture of sand and pebble-size pumice fragments in the upper part. The climate is characterized by cool, dry summers and cold, wet winters. Average annual precipitation is 70 to 90 inches including snowfall. Average annual temperature is 42 to 44 degrees F. The growing season (28 degrees F) is 150 to 180 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are Bellicum, Bromo, Cinebar, Domell, Hatchet, Schneider, and Zynbar soils. Bellicum soils are cindery over medial-skeletal. Bromo soils are cindery over medial. Cinebar soils are medial and have a mesic temperature regime. Domell soils are medial and have an umbric epipedon. Hatchet soils have a cryic temperature regime, have a spodic horizon and are 20 to 40 inches deep to bedrock. Schneider soils are loamy-skeletal and have a mesic temperature regime. Zynbar soils are medial.
DRAINAGE AND PERMEABILITY: Well drained; medium to very rapid runoff; moderate permeability.
USE AND VEGETATION: Used for timber production, wildlife habitat and watershed. Overstory vegetation is Douglas-fir, western hemlock and western redcedar. Ground vegetation includes Oregon oxalis, Pacific trillium, salal, Oregon-grape, western swordfern, trailing blackberry, bedstraw, American trailplant, red huckleberry, devilsclub, starflower, deer fern, darkwoods violet, mosses and lichens.
DISTRIBUTION AND EXTENT: Mountainsides of the Cascade Range in southern Lewis and northeastern Cowlitz Counties, Washington. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Lewis County, Washington, 1979.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
ochric epipedon from the mineral surface to 4 inches; a cambic horizon from 4 to 47 inches; and a lithic contact at 47 inches. This description reflects a change in classification based on the 1998 Keys to Soil Taxonomy. The upper 7 to 14 inches has an estimated moist bulk density of less than 1.00 g/cc, volcanic glass content of less than 5 percent, acid-oxalate extractable aluminum plus one-half iron of more than 2 percent. Bulk density is more than 0.90 g/cc below 14 inches.