LOCATION SKIPJACK WAEstablished Series
TAXONOMIC CLASS: Coarse-loamy, isotic, mesic Andic Dystroxerepts
TYPICAL PEDON: Skipjack fine sandy loam, forested, on a northwest-facing sideslope of 6 percent at 305 meters elevation. (Colors are for dry soil unless otherwise noted. When described on July 29, 2004 the soil was dry throughout.)
Oi--0 to 8 cm; slightly decomposed plant material; abrupt wavy boundary. (3 to 8 cm thick)
Bw1--8 to 81 cm; strong brown (7.5YR 5/6) fine sandy loam, dark yellowish brown (10YR 3/4) moist; weak, fine, subangular blocky structure; soft, very friable, nonsticky and nonplastic; many very fine, fine, and medium roots, and common coarse roots; many very fine and fine irregular pores; 10 percent gravel; NaF pH 10.8; strongly acid (pH 5.4); clear wavy boundary. (28 to 84 cm thick)
Bw2--81 to 109 cm; yellowish brown (10YR 5/6) gravelly sandy loam, dark yellowish brown (10YR 4/4) moist; moderate medium subangular blocky structure; soft, friable, nonsticky and nonplastic; common fine and medium roots; many very fine and fine irregular pores; 15 percent gravel; NaF pH 10.8; moderately acid (pH 5.6); clear wavy boundary. (15 to 58 cm thick)
2Bg--109 to 152 cm; light olive brown (2.5Y 5/4) gravelly coarse sandy loam, olive brown (2.5Y 4/4) dry; massive; slightly hard, friable, nonsticky and nonplastic; few fine and medium roots; few very fine irregular pores; many distinct dark yellowish brown (10YR 4/6) moist iron-manganese masses throughout; many distinct dark gray (2.5Y 4/1) moist iron depletions throughout; 15 percent gravel; NaF pH 10.7; moderately acid (pH 5.6)
TYPE LOCATION: Orcas Island, San Juan County, Washington; 315 meters north and 315 meters east of the southwest corner of sec. 34, T. 37 N., R. 1 W. Willamette Meridian. USGS Mount Constitution SE quarter quadrangle; lat. 48 degrees 38 minutes 53 seconds N. and long. 122 degrees 48 minutes 35 seconds W.
RANGE IN CHARACTERISTICS: Depths to diagnostic horizons and features start from the mineral soil surface.
Average annual soil temperature - 9 to 10 degrees C.
Soil moisture control section - dry 45 to 60 days following summer solstice
Depth to lithic contact - greater than 150 cm
Reaction - strongly acid to moderately acid
Particle size control section:
Clay content - 5 to 15 percent
Rock fragments - 0 to 35 percent
Bw1 horizon
Hue - 10YR to 7.5YR
Value - 3 or 4 moist, 5 to 6 dry
Chroma - 3 to 6 moist or dry
Ammonium oxalate extractable aluminum plus one half iron - 1.5 to 2.5 percent
Bulk Density - 0.8 to 1.0 g/cm3
Phosphorous retention - 50 to 80 percent
Volcanic glass - 0 to 4 percent
Rock fragments - 0 to 15 percent gravel
Clay content - 5 to 15 percent
Bw2 horizon
Hue - 10YR to 7.5YR
Value - 3 or 4 moist, 5 to 6 dry
Chroma - 3 to 6 moist or dry
Texture - L, SL, or FSL
Ammonium oxalate extractable aluminum plus one half iron - 1.5 to 2.5 percent
Bulk Density - 0.8 to 1.0 g/cm3
Phosphorous retention - 50 to 80 percent
Volcanic glass - 0 to 4 percent
Rock fragments - 0 to 35 percent gravel, 0 to 10 percent cobbles, 0 to 5 percent stones, 0 to 35 percent total
Clay content - 5 to 15 percent
2Bg horizon
Value - 3 or 4 moist, 4 to 6 dry
Chroma - 3 to 6 moist or dry
Texture - SL, or COSL
Rock fragments - 0 to 35 percent gravel, 0 to 10 percent cobbles, 0 to 5 percent stones, 0 to 35 percent total
Clay content - 3 to 15 percent
COMPETING SERIES: These are the Constitution (T), Kapowsin, Menzel, and Sadie series. Constitution soils have a lithic contact at 50 to 100 cm. Kapowsin soils formed in dense glacial till, have redoximorphic features within 100 cm, and are 50 to 100 cm deep to a pan cemented with aluminum, iron, and organic matter. Menzel soils are medial in the A and Bw horizons, and have pH ranging from slightly acid to neutral in the particle-size control section. Sadie soils have a densic contact at 65 to 100 cm and have redoximorphic features within 100 cm.
GEOGRAPHIC SETTING: Skipjack soils occur on hillslopes and mountain slopes. Slope ranges from 5 to 15 percent and elevations range from 0 to 732 meters. The soils formed in colluvium from glacial drift, bedrock of metasedimentary lithology, and volcanic ash. The climate is characterized by warm, dry summers and mild, moist winters with intermittent snow cover. The annual precipitation ranges from 890 to 1,140 millimeters. The average annual air temperature ranges from 8 to 9 degrees C. The frost-free season is 160 to 220 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Constitution, Kahboo, and Pickett series. Constitution soils have a lithic contact at 50 and 100 cm and occur on hillslopes and mountain slopes. Kahboo soils have a lithic contact at 25 and 50 cm and occur on summits, hillslopes, and mountain slopes. Pickett soils have greater than 35 percent rock fragments in the particle-size control section and occur on adjacent hillsides and mountainsides.
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained. Saturated hydraulic conductivity is high. Skipjack soils have a water table as high as 109 cm from October to May. These soils are not subject to ponding.
USE AND VEGETATION: Used for timber production, recreation, wildlife habitat, homesites, and watershed. Potential natural vegetation consists of western hemlock, Douglas-fir, western redcedar, Cascade Oregongrape, prickly currant, false Solomons-seal, swordfern, and bracken fern.
DISTRIBUTION AND EXTENT: Northwest Washington; MLRA A2, Northern Part. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: San Juan County, Washington, 2006. The name is taken from Skipjack Island in northwestern San Juan County.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon
Andic subgroup properties - 8 to 109 cm (Bw horizons)
Cambic horizon - 8 to 109 cm (Bw horizons)
Particle-size control section - 33 to 108 cm
Redoximorphic features - 109 to 150 cm
Bulk density in the Bw horizons is assumed to be less than 1 g/cm3