LOCATION FLATBOTTOM WAEstablished Series
TAXONOMIC CLASS: Medial-skeletal, ferrihydritic, isofrigid Pachic Fulvudands
TYPICAL PEDON: Flatbottom extremely gravelly medial silt loam - forestland on an 86 percent south-southwesterly aspect at an elevation 1,480 feet in a Pacific silver fir/swordfern-oxalis plant association. (When described on July 24, 1998, 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, and cone fragments; abrupt smooth boundary. (1 to 2 inches thick)
Oe--1 to 2 inches; moderately decomposed organic materials; abrupt smooth boundary. (0 to 2.5 inches thick)
Oa--2 to 3 inches; highly decomposed organic materials; abrupt smooth boundary. (0 to 1.5 inches thick)
A--3 to 7 inches; black (10YR 2/1) extremely gravelly medial silt loam, dark brown (10YR 3/3) 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; many very fine, fine, medium, and coarse roots; many very fine and fine tubular and irregular pores; 85 percent gravel; very strongly acid (pH 4.6); clear smooth boundary. (3 to 6 inches thick)
Bw1--7 to 14 inches; dark brown (10YR 3/3) extremely gravelly medial silt loam, yellowish brown (10YR 5/4) 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 tubular and irregular pores; 75 percent gravel; very strongly acid (pH 4.8); clear wavy boundary.
Bw2--14 to 19 inches; dark yellowish brown (10YR 3/4) extremely gravelly medial silt 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; common very fine, fine, medium, and coarse roots; common very fine and fine tubular and irregular pores; 75 percent gravel; very strongly acid (pH 5.0); clear wavy boundary.
Bw3--19 to 27 inches; dark yellowish brown (10YR 3/4) extremely gravelly medial silt loam, yellowish brown (10YR 5/6) 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, medium, and coarse roots; common very fine and fine tubular and irregular pores; 70 percent gravel, 5 percent cobbles; strongly acid (pH 5.4); clear wavy boundary.
Bw4--27 to 33 inches; strong brown (7.5YR 4/6) extremely gravelly medial silt loam, brownish yellow (10YR 6/6) 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; moderately smeary; common very fine and fine and few medium and coarse roots; common very fine and fine tubular and irregular pores; 60 percent gravel, 5 percent cobbles; very strongly acid (pH 4.8); abrupt wavy boundary. (Combined thickness of the Bw horizon is 17 to 34 inches.)
R--33 inches; marine basalt.
TYPE LOCATION: Grays Harbor County, Washington, about 5 miles south of Quinault, about 2,270 feet east and 1,690 feet north of the southwest corner of Section 17, T. 22 N., R. 9 W. (Latitude 47 degrees, 23minutes, 34 seconds N., Longitude 123 degrees, 50 minutes, 58 seconds W.)
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 43 to 47 degrees F. The mean summer soil temperature is 47 to 50 degrees F. and the mean winter soil temperature is 40 to 45 degrees F. The difference between the mean winter and mean summer soil temperature is 5 to 9 degrees F. These soils are usually moist and are dry 0 to 30 consecutive days in the soil moisture control section; udic moisture regime. Depth to bedrock is 20 to 40 inches. The umbric epipedon is 10 to 20 inches thick. The solum has andic soil properties with 40 to 90 percent rock fragments by volume. The andic soil material has an estimated moist bulk density of 0.30 to 0.70 g/cc, acid-oxalate extractable aluminum plus one half of the acid-oxalate extractable iron of 2 to 6 percent, phosphate retention of 85 to 100 percent, and 15-bar water retention of 25 to 40 percent for air-dried samples. Acid oxalate iron is 1.5 to 3.5 percent. It has 2 to 5 cmol/kg of aluminum throughout the upper 20 inches of the solum. The particle-size control section has 5 to 20 percent field estimated clay and 20 to 40 percent sand.
The A horizon has hue of 10YR or 7.5YR moist and dry, value of 2 or 3 moist and 3 or 4 dry, and chroma of 1 or 2 moist and 2 or 3 dry. It has 20 to 30 percent organic matter.
The Bw horizon has hue of 10YR or 7.5YR moist and dry, value of 3 or 4 moist and 4 through 6 dry, and chroma of 3, 4, or 6 moist and 4 or 6 dry. It is very gravelly medial silt loam, extremely gravelly medial silt loam, or extremely gravelly medial loam. Reaction is very strongly acid or strongly acid. It has 10 to 20 percent organic.
COMPETING SERIES: These are the Elklake, Fawceter, Killam, Larsencreek, McKinnon, Urboden and Zenobia series. Elklake soils have a perudic soil moisture regime. Larsencreek and McKinnon soils are deep and very deep. Fawceter soils are deep. Urboden soils are very deep and perudic. Zenobia soils have an umbric epipedon 20 to 40 inches thick and are perudic. Killam soils have an umbric epipedon 20 to 40 inches thick.
GEOGRAPHIC SETTING: Flatbottom soils are on mountain slopes, dissected mountain slopes, and mountain headwalls. Slopes are 60 to 100 percent. The soils formed in colluvium from marine basalt. Elevations are 800 to 2900 feet. Average annual precipitation is 140 to 170 inches. Fog drip contributes to the effective precipitation totals. Average annual temperature is 41 to 43 degrees F. The frost-free season is 120 to 140 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Eatoncreek, Elklake, Larsencreek, Lizardlake, and McKinnon soils. Eatoncreek and Lizardlake soils are on dissected mountain slopes and mountain headwalls and are shallow. Elklake soils are on mountain slopes, dissected mountain slopes, and mountain headwalls and have a perudic soil moisture regime. Larsencreek and McKinnon soils are on mountain slopes and dissected mountain slopes and are both deep and very deep.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: Timber production, wildlife habitat, recreation, and watershed. Native vegetation is western hemlock, Pacific silver fir, western redcedar, western swordfern, Oregon oxalis, Alaska huckleberry, red huckleberry, fool's huckleberry, salal, and Oregon-grape.
DISTRIBUTION AND EXTENT: Grays Harbor County, Washington; MLRA 1. Series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Grays Harbor County, Washington, 2000; Olympic National Forest.
REMARKS: Diagnostic horizons and features recognized in this pedon are the following:
Umbric epipedon - 3 to 14 inches
Cambic horizon - 14 to 33 inches
Andic soil properties - 3 to 33 inches (A and Bw1 through Bw4 horizons)
Lithic contact - 33 inches
PSCS - 3 to 33 inches (A and Bw1 through Bw4 horizons)
All depths to diagnostic horizons and other features are measured from the top of the first mineral horizon.
ADDITIONAL DATA: Pedon NSSL S98WA-027-002.