LOCATION KAHKWA WAEstablished Series
TAXONOMIC CLASS: Medial-skeletal, ferrihydritic Typic Haplocryands
TYPICAL PEDON: Kahkwa very gravelly medial sandy loam-forestland on a 35 percent west-southwesterly aspect at an elevation of 1840 feet in a Pacific silver fir/Alaska huckleberry-oxalis plant association. (When described on July 16, 1996, the soil was moist throughout. Colors are for moist soil unless otherwise stated. All textures are apparent field textures.)
Oi--0 to 2 inches; slightly decomposed needles, leaves, twigs, and other wood fragments; abrupt smooth boundary. (1 to 3 inches thick)
A--2 to 6 inches; dark brown (10YR 3/3) gravelly medial sandy loam, yellowish brown (10YR 5/4) dry; weak very fine and fine subangular blocky and weak very fine and fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; weakly smeary; many very fine and common fine, medium, and coarse roots; common very fine and fine irregular pores; 25 percent gravel; very strongly acid (pH 4.6); clear wavy boundary. (3 to 5 inches thick)
Bw1--6 to 10 inches; dark yellowish brown (10YR 3/4) very gravelly medial sandy loam, light yellowish brown (10YR 6/4) dry; weak very fine and fine subangular blocky and weak very fine and fine granular structure; slightly hard, friable, nonsticky and nonplastic; weakly smeary; common very fine, fine, medium, and coarse roots; common very fine and fine irregular pores; 35 percent gravel; very strongly acid (pH 5.0); clear wavy boundary.
Bw2--10 to 26 inches; dark yellowish brown (10YR 3/6) very gravelly medial fine sandy loam, very pale brown (10YR 7/4) dry; weak very fine, fine, and medium subangular blocky and weak very fine and fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; weakly smeary; common very fine, fine, medium, and coarse roots; common very fine and fine irregular pores; 30 percent gravel, 5 percent cobbles; strongly acid (pH 5.4); clear wavy boundary.
Bw3--26 to 35 inches; dark yellowish brown (10YR 3/4) very gravelly medial fine sandy loam, light yellowish brown (10YR 6/4) dry; weak very fine, fine, and medium subangular blocky and weak very fine and fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; weakly smeary; common very fine, fine, medium, and coarse roots; common very fine and fine irregular pores; 35 percent gravel, 15 percent cobbles; moderately acid (pH 5.6); clear wavy boundary.
Bw4--35 to 43 inches; dark yellowish brown (10YR 3/6) very gravelly medial fine sandy loam, brownish yellow (10YR 6/6) dry; weak very fine and fine subangular blocky and weak very fine and fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; weakly smeary; common very fine, fine, and medium and few coarse roots; common very fine and fine irregular pores; 45 percent gravel, 5 percent cobbles; moderately acid (pH 5.6); clear wavy boundary.
Bw5--43 to 54 inches; dark yellowish brown (10YR 3/6) extremely gravelly medial sandy loam, very pale brown (10YR 7/4) dry; weak very fine and fine subangular blocky and weak very fine and fine granular structure; slightly hard, friable, nonsticky and nonplastic; weakly smeary; common very fine and fine and few medium and coarse roots; few very fine and fine irregular pores; 50 percent gravel, 10 percent cobbles; moderately acid (pH 5.6). (Combined thickness of the Bw horizon is 45 to 57 inches)
BC--54 to 62 inches; dark yellowish brown (10YR 3/6) extremely gravelly loamy sand, light yellowish brown (10YR 6/4) dry; weak very fine and fine subangular blocky and weak very fine and fine granular structure; slightly hard, friable, nonsticky and nonplastic; few very fine and fine roots; few very fine irregular pores; 55 percent gravel 10 percent cobbles; moderately acid (pH 5.8). (0 to 10 inches thick)
TYPE LOCATION: Clallam County, Washington, about 4 1/3 miles north of Fifteenmile Shelter, about 2330 feet east and 2420 feet north of the southwest corner of Section 32, T. 29 N., R. 10 W. (Latitude 47 degrees, 57 minutes, 52 seconds N., Longitude 124 degrees, 01 minutes, 11 seconds W.)
RANGE IN CHARACTERISTICS: Mean annual soil temperature is 43 to 45 degrees F. The mean summer soil temperature is 45 to 47 degrees F. The mean winter soil temperature is 40 to 44 degrees F. The difference between mean summer and mean winter soil temperature is 3 to 5 degrees F. These soils are usually moist, and are dry 0 to 30 consecutive days in the soil moisture control section; udic soil moisture regime. Depth to bedrock is greater than 60 inches. The particle-size control section has andic soil properties and 25 to 75 percent rock fragments by volume with a weighted average of over 35 percent. The andic soil material has an estimated moist bulk density of 0.70 to 0.90 g/cc, acid-oxalate extractable aluminum plus one half of the acid-oxalate extractable iron of 2 to 3 percent, phosphate retention of 85 to 100 percent, and 15-bar water retention of 15 to 30 percent of air dried samples. The particle-size control section has 5 to 18 percent field estimated clay and 40 to 60 percent sand. It has 1 to 2 cmol/kg of aluminum in the subsoil. Acid oxalate extractable iron is 1.5 to 3.0 percent.
The A horizon has chroma of 3 or 4 dry. It has 10 to 20 percent organic matter.
The Bw horizon has value of 5 through 7 dry and chroma of 4 or 6 moist and dry. It is very gravelly medial sandy loam, very gravelly medial fine sandy loam, extremely gravelly medial sandy loam, or very gravelly medial loam. Reaction is very strongly acid in the upper part and strongly or moderately acid below. It has 1 to 10 percent organic matter with less than 7 percent below a depth of 10 inches from the mineral soil surface.
The BC horizon has value of 3 or 4 moist and 6 or 7 dry. It is extremely gravelly loamy sand, extremely gravelly sandy loam, or very gravelly sandy loam. Moist bulk density is 0.90 to 1.20 g/cc. It has less than 1 to 2 percent organic matter.
COMPETING SERIES: These are Balcher, Blackjack, Fahnestock, Mueller, Musgrove, Sorethumb, Sniderpeak, Stonybrook, and Tylerpeak series. Balcher soils are deep to dense glacial till. Tylerpeak, Sniderpeak, Stonybrook and Sorethumb soils are moderately deep to bedrock. Mueller soils are dry for 30 to 45 consecutive days (40 to 70 inches of precipitation). Fahnestock and Musgrove sols are over basalt and have a difference of 6 to 9 degrees F between mean summer and mean winter soil temperature. Blackjack soils are deep to sedimentary bedrock and are on non-glaciated mountains.
GEOGRAPHIC SETTING: Kahkwa soils are on glacial valleys. Slopes are 30 to 60 percent. The soils formed in colluvium and residuum from sedimentary and metasedimentary rocks. Elevations are 1400 to 2300 feet. Average annual precipitation is 95 to 120 inches. Average annual temperature is 41 to 43 degrees F. The frost-free season is 130 to 150 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Blackjack and Sorethumb soils and the Constance and Huntcreek soils. Blackjack soils are deep to bedrock. Sorethumb soils are moderately deep to bedrock. Constance soils are shallow to bedrock. Huntcreek soils are on glacial valleys and are moderately deep to till.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: Timber production, wildlife habitat, recreation, and watershed. Native vegetation is Pacific silver fir, western hemlock, Alaska huckleberry, Oregon oxalis, deer fern, threeleaf foamflower, false lily-of-the-valley, five leaf bramble, ladyfern, red huckleberry, deerfoot vanillaleaf, queencup beadlily, and bunchberry dogwood.
DISTRIBUTION AND EXTENT: Olympic Mountains, western slope, Clallam County, Washington; MLRA 3. 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 54 inches
Andic soil properties - 2 to 54 inches
PSCS - 2 to 42 inches
All depths to diagnostic horizons and other features are measured from the top of the first mineral horizon.