LOCATION ELWHA WA

Established Series
Rev. EED/MPR
09/2011

ELWHA SERIES

The Elwha series consists of moderately deep, moderately well drained soils formed in glacial drift over dense glacial drift on glacially modified hills. Slopes are 0 to 35 percent. The mean annual precipitation is about 830 millimeters and the mean annual temperature is about 10.0 degrees C.

TAXONOMIC CLASS: Coarse-loamy, isotic, mesic Aquic Dystroxerepts

TYPICAL PEDON: Elwha gravelly sandy loam, forested, on a north-facing slope of 30 percent. (All colors are for moist soil unless otherwise noted.)

Oi -- 0 to 3 cm; slightly decomposed needles, leaves, and twigs.

Oe -- 3 to 5 cm; moderately decomposed needles, leaves, and twigs.

A -- 5 to 15 cm; dark brown (10YR 3/3) gravelly sandy loam, pale brown (10YR 6/3) dry; weak fine and very fine granular structure; soft, friable, nonsticky and nonplastic; many very fine and fine roots; many fine irregular and tubular pores; 15 percent gravel; strongly acid (pH 5.4); gradual smooth boundary. (8 to 10 centimeters thick)

Bw1 -- 15 to 36 cm; brown (10YR 4/3) gravelly sandy loam, very pale brown (10YR 7/3) dry; weak very fine and fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine and fine and common medium roots; many fine irregular and tubular pores; 15 percent gravel and 5 percent cobbles; strongly acid (pH 5.4); gradual smooth boundary. (10 to 25 centimeters thick)

Bw2 -- 36 to 66 cm; dark yellowish brown (10YR 4/4) gravelly sandy loam, very pale brown (10YR 7/4) dry; weak fine and very fine subangular blocky structure; hard, friable, slightly sticky and slightly plastic; many very fine and fine and common medium roots; many fine irregular and tubular pores; 20 percent gravel and 5 percent cobbles; strongly acid (pH 5.4); clear smooth boundary. (combined thickness of the Bw horizons is 30 to 55 centimeters)

Bg -- 66 to 89 cm; dark yellowish brown (10YR 4/4) gravelly sandy loam, very pale brown (10YR 7/4) dry; many coarse distinct yellowish brown (10YR 5/6) iron-manganese masses, yellow (10YR 7/6) dry; many coarse distinct light brownish gray (10YR 6/2) iron depletions, light gray (10YR 7/2) dry; weak medium and fine subangular blocky structure; hard, firm, slightly sticky and slightly plastic; common very fine and fine roots; common very fine irregular and tubular pores; 20 percent gravel and 5 percent cobbles; moderately acid (pH 5.6); clear smooth boundary. (10 to 23 centimeters thick) does this series sometimes not have a Bg?

2Cd1 -- 89 to 112 cm; light yellowish brown (2.5Y 6/4) gravelly sandy loam, pale yellow (2.5Y 7/4) dry; common coarse distinct dark yellowish brown (10YR 4/6), iron-manganese masses, brownish yellow (10YR 6/6) dry; massive; very hard, firm, slightly sticky and slightly plastic; few very fine roots in cracks; few fine irregular and tubular pores; 15 percent gravel; slightly acid (pH 6.2); clear smooth boundary. (0 to 36 centimeters thick)

2Cd2 -- 112 to 152 cm; grayish brown (2.5Y 5/2) gravelly sandy loam, light gray (2.5Y 7/2) dry; few coarse distinct dark yellowish brown (10YR 4/6) iron-manganese masses, brownish yellow (10YR 6/6) dry; massive; very hard, firm, slightly sticky and slightly plastic; very few very fine roots in cracks; few fine irregular pores; 15 percent gravel; neutral (pH 6.8).

TYPE LOCATION: Clallam County, Washington; 600 meters west and 300 meters south of the northeast corner of section 12, T. 29 N., R. 5 W. Willamette Baseline Meridian; USGS Morse Creek, Washington quadrangle; latitude 48 degrees, 1 minutes, 34.00 seconds N and longitude 123 degrees, 44.00 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.
Moisture control section - dry 60 to 75 days following the summer solstice
Depth to densic contact - 50 to 100 cm
Depth to redoximorphic features - 46 to 100 cm
Reaction - strongly acid to neutral
Volcanic glass content less than 5 percent in the upper 75 cm
Acid-oxalate extractable Al and Iron less than 1 percent in the upper 75 cm
Particle size control section:
Clay content - 5 to 18 percent
Rock fragments - 0 to 35 percent gravel, 0 to 5 percent cobbles, and 0 to 35
percent total

A horizon
Value - 3 or 4 moist, 5 to 7 dry
Chroma - 3 or 4 moist or dry
Rock fragments - 15 to 35 percent gravel

Bw horizons
Hue - 10YR or 2.5Y
Value - 4 to 6 moist, 6 to 8 dry
Chroma - 2 to 4
Texture - L, SL, or COSL
Rock fragments 0 to 35 percent gravel, 0 to 5 percent cobbles, and 0 to 35 percent total

Bg horizon
Value - 4 or 5 moist, 6 or 7 moist
Chroma - 3 or 4 moist or dry
Texture - SL or COSL
Rock fragments - 0 to 25 percent gravel

Cd horizons
Hue - 2.5y or 5y
Value - 4 to 6 moist, 7 or 8 dry
Texture L or SL
Rock fragments - 0 to 25 percent gravel

COMPETING SERIES: These are the Morancreek, Roche, and Zylstra series. Morancreek soils lack a densic contact. Roche soils are dry in the soil moisture control section from 75 to 90 days following the summer solstice. Zylstra soils have redoximorphic features within 20 to 41 cm of the soil surface.

GEOGRAPHIC SETTING: Elwha soils are on hillslopes of glacial drift plains at elevations of 0 to 610 meters. They formed in glacial drift over dense glacial drift. These soils are in a mild marine climate with cool, dry summers and mild, wet winters. Mean annual precipitation is 625 to 1150 millimeters. Mean annual air temperature is about 10 degrees C. Frost-free season is 160 to 240 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Clallam, Indianola, Louella, McKenna, Morancreak, Neilton, Terbies, Yeary and Zylstra soils. Clallam soils occur on hillslopes and have greater than 35 percent coarse fragments in the control section. Indianola soils occur on hillslopes and terraces and have a sandy control section. Louella, Morancreek, and McKenna soils occur on adjacent hillslopes and lack a densic contact. Neilton soils occur on terraces and have a sandy control section. Terbies soils occur on glacially modified bedrock hills and have a lithic contact from 100 to 152 cm. Yeary soils occur on hillslopes and have greater than 18 percent clay in the control section. Zylstra soils occur on adjacent hillslopes and have redoximorphic features within 20 to 41 cm of the soil surface.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Moderately well drained; Saturated hydraulic conductivity is high in the A and Bw horizons, moderately high in the Bg horizon and low in the 2Cd horizons. Elwha soils have a perched water table as high as 40 centimeters from November to March.

USE AND VEGETATION: These soils are used for livestock grazing, forage crop production, timber production, and homesites. Potential natural vegetation consists of western hemlock, Douglas-fir, western redcedar, bigleaf maple, swordfern, red huckleberry, evergreen huckleberry, salal, oceanspray and trailing blackberry.

DISTRIBUTION AND EXTENT: Northwestern Washington; MLRA 2, North. Series is of moderate extent.

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

SERIES ESTABLISHED: Clallam County, Washington, 1943.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon
Cambic horizon - 15 to 66 cm (Bw horizons)
Densic Contact - 89 cm (upper boundary of the Cd horizons)
Particle size control section - the zone from 25 to 89 cm (to the Cd horizon)
Depth to redoximorphic features - 66 cm (Bg horizon)

This revision (2/2008) includes a change in classification based on lab data and field investigations. The previous classification was coarse-loamy, isotic, mesic Andic Haploxerepts.

ADDITIONAL DATA: NSSL pedon # 79P0103.

National Cooperative Soil Survey
U.S.A.