LOCATION TURTLEBACK              WA

Established Series
Rev. EED/JDO/SBC
06/2011

TURTLEBACK SERIES

The Turtleback series consists of deep, well drained soils formed in colluvium from glacial drift and bedrock of metasedimentary lithology. Turtleback soils are on hillslopes and mountain slopes. Slopes are 25 to 75 percent. The mean annual precipitation is about 610 mm and the mean annual temperature is about 9 degrees C.

TAXONOMIC CLASS: Loamy-skeletal, isotic, mesic Humic Dystroxerepts

TYPICAL PEDON: Turtleback very gravelly very fine sandy loam, forested, on a west-facing hillslope of 45 percent at 305 meters elevation. When described on August 4, 2004 the soil was dry throughout. (Colors are for dry soil unless otherwise noted.)

Oi--0 to 8 cm; slightly decomposed needles, twigs and bark; abrupt wavy boundary. (0 to 8 cm thick)

Bw1--8 to 33 cm; dark yellowish brown (10YR 4/6) very gravelly very fine sandy loam, dark yellowish brown (10YR 3/4) moist; weak very fine subangular blocky structure; soft, very friable, nonsticky, nonplastic; many very fine, fine, and medium, and few coarse roots; few fine interstitial and many fine irregular pores; 15 percent fine gravel, 20 percent medium and coarse gravel, and 10 percent cobbles; strongly acid (pH 5.4); clear wavy boundary. (18 to 25 cm thick)

Bw2--33 to 102 cm; light olive brown (2.5Y 5/6) extremely gravelly sandy loam, olive brown (2.5Y 4/4) moist; weak medium subangular blocky structure; soft, very friable, nonsticky, nonplastic; common very fine and fine, and few medium roots; few fine interstitial and common fine irregular pores; 20 percent fine gravel, 20 percent medium and coarse gravel, and 20 percent stones; moderately acid (pH 5.6); gradual wavy boundary. (80 to 100 cm thick)

C--102 to 122 cm; light olive brown (2.5Y 5/3) extremely gravelly loamy sand, dark grayish brown (2.5Y 4/2) moist; single grain; loose, nonsticky, nonplastic; few very fine, fine and medium roots; common fine interstitial pores; 30 percent fine gravel, 30 percent medium and coarse gravel and 5 percent cobbles; moderately acid (pH 5.6); abrupt wavy boundary. (0 to 60 cm thick)

R--122 cm; metasedimentary bedrock.

TYPE LOCATION: Orcas Island, San Juan County, Washington; 150 meters east and 5 meters north of the southwest corner of section 27, T. 37 N., R. 1 W. Willamette Meridian; USGS Mount Constitution SE quarter quadrangle; latitude 48 degrees 39 minutes 35 seconds N. and longitude 122 degrees 48 minutes 43 seconds W.

RANGE IN CHARACTERISTICS: Depths to diagnostic horizons and features start from the mineral soil surface.

Mean annual soil temperature - 10 to 11 degrees C.
Soil moisture control section - dry 75 to 90 days following the summer solstice
Depth to lithic contact - 100 to 150 cm.
Reaction - Strongly acid to moderately acid
Volcanic glass - 0 to 4 percent in the Bw horizons
Particle size control section:
Clay content - 5 to 18 percent
Rock fragments - 35 to 75 percent gravel, 0 to 10 percent cobbles, 0 to 10 percent stones, 35 to 75 percent total

Bw1 horizon
Hue - 7.5YR or 10YR
Value - 3 moist, 4 or 5 dry
Chroma - 2 to 4 moist, 4 to 6 dry
Clay content - 5 to 18 percent
Rock fragments - 35 to 60 percent gravel, 0 to 10 percent cobbles, 0 to 5 percent stones, 35 to 60 percent total

Bw2 horizon
Hue - 10YR to 2.5Y
Value - 3 or 4 moist, 5 or 6 dry
Chroma - 3 or 4 moist, 4 to 6 dry
Texture - SL or LS
Clay content - 5 to 18 percent
Rock fragments - 35 to 70 percent gravel, 0 to 10 percent cobbles, 0 to 10 percent stones, 35 to 70 percent total

C Horizon
Hue - 10YR to 2.5Y
Value - 4 or 5 moist, 4 to 7 dry
Chroma - 2 to 4 moist, 2 to 6 dry
Texture - LS, FSL, SL, COSL
Clay content - 1 to 12 percent
Rock Fragments - 50 to 75 percent gravel, 0 to 10 percent cobbles, 0 to 10 percent stones, 50 to 75 percent total

COMPETING SERIES: These are the Billscabin, Doebay, and Inskip series. Billscabin soils are more than 150 cm deep to a paralithic contact. Doebay soils have a lithic contact at 50 to 100 cm. Inskip soils are 50 to 109 cm to a lithic contact with vesicular basaltic lava bedrock, and rock fragments are vesicular basalt from recent lava flows. Series with similar classification but mixed mineralogy include the Atring, Barpeak, Beekman, Farber, Firmountain, Forgay, Geppert, Half Dome, Hartless, Hilltish, Howler (T), Kanid, Kindig, Mayacama, Neuns, Sheetiron, Straight, Vena, and Woodin soils. Atring, Beekman, Firmountain, Geppert, Hilltish, Mayacama, Neuns, Sheetiron, Straight, Vena, and Woodin soils have a lithic or paralithic contact at 50 to 100 cm. Barpeak, Farber, Forgay, Half Dome, and Howler (T) soils are greater than 150 cm to a lithic contact. Hartless soils have a paralithic contact at 100 to greater than 150 cm. Kanid soils have a paralithic contact of fractured metamorphic sandstone at 100 to 150 cm, and are dry for 45 to 60 consecutive days following the summer solstice. Kindig soils have a paralithic contact of weathered schist bedrock at 100 to 150 cm.

GEOGRAPHIC SETTING: Turtleback soils occur on mountain slopes and hillslopes at elevations of sea level to 730 meters. Slopes are 25 to 75 percent. These soils formed in colluvium from glacial drift and bedrock of metasedimentary lithology. The climate is characterized by warm dry summers and mild moist winters. Mean annual precipitation ranges from 457 to 762 mm. Mean annual air temperature is 9 degrees C. The frost-free period is 200 to 240 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cady, Doebay, Haro, and Hiddenridge soils. All of these soils occur on adjacent hillslopes and mountain slopes. Cady soils have a lithic contact within 50 cm. Doebay soils have a lithic contact between 50 and 100 cm. Haro soils have a lithic contact within 50 cm and a mollic epipedon. Hiddenridge soils have an umbric epipedon.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; Saturated hydraulic conductivity is high.

USE AND VEGETATION: Used for timber production, recreation, wildlife habitat, homesites, and watershed. Potential natural vegetation consists of Douglas-fir, Pacific madrone, lodgepole pine, oceanspray, baldhip rose, salal, Cascade Oregongrape, rattlesnake plantain, and bracken fern.

DISTRIBUTION AND EXTENT: Northwest Washington; MLRA 2. Series is of small extent.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon

SERIES ESTABLISHED: San Juan County, Washington, 2006.

REMARKS: Diagnostic horizons and features recognized in this pedon are;
Ochric epipedon
Humic subgroup - color requirements are meet from 8 to 33 cm.
Cambic horizon - 8 to 102 cm (Bw horizons)
Lithic contact - 122 cm (R horizon)
Particle-size control section - 33 to 108 cm

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National Cooperative Soil Survey
U.S.A.