LOCATION EDFRO WAEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, magnesic, shallow Typic Haplocryods
TYPICAL PEDON: Edfro very gravelly silt loam - on a 30 percent northeast-facing convex slope in a clearcut at 3,500 feet elevation. (Colors are for moist soil unless otherwise noted. All textures are apparent field textures.)
0i--0 to 0.5 inches; slightly decomposed needles, leaves, twigs.
0a--0.5 to 4 inches; decomposed needles, twigs, bark; many very fine and common fine roots.
E--4 to 7 inches; brown (7.5YR 5/2) very gravelly silt loam, pinkish gray (7.5YR 7/2) dry; massive; soft, very friable, nonsticky, nonplastic; weakly smeary; common very fine and fine roots; many very fine irregular pores; 30 percent pebbles and 5 percent cobbles; NaF pH l0.0; extremely acid (pH 4.0); abrupt wavy boundary. (2 to 5 inches thick)
Bsl--7 to 11 inches; strong brown (7.5YR 4/6) very gravelly silt
loam, strong brown (7.5YR 5/8) dry; dark reddish brown (2.5YR 3/4) organic stains on faces of peds, yellowish red (5YR 4/6) dry; moderate medium and coarse subangular blocky structure; very hard, very firm, nonsticky, nonplastic, weakly smeary; common very fine roots; many very fine irregular pores; 45 percent pebbles and l0 percent cobbles; NaF pH ll.5; very strongly acid (pH 4.8); clear wavy boundary. (3 to 9 inches thick)
Bs2--11 to 21 inches; yellowish red (5YR 4/6) extremely
gravelly silt loam, yellowish red (5YR 5/6) dry; dark reddish brown (2.5YR 3/4) organic stains on faces of peds, reddish brown (5YR 4/4) dry; moderate medium subangular blocky structure; hard, firm, nonsticky, nonplastic, weakly smeary; few very fine roots; common very fine irregular pores; 50 percent pebbles and l0 percent cobbles; NaF pH l2.0; very strongly acid (pH 5.0); clear wavy boundary. (4 to l0 inches thick)
Bs3--21 to 23 inches; dark brown (7.5YR 4/4) extremely
gravelly loam, strong brown (7.5YR 4/6); massive; slightly hard, friable, nonsticky, nonplastic, weakly smeary; very few very fine roots; many fine irregular pores; 60 percent pebbles; NaF pH l2.0; very strongly acid (pH 5.0); abrupt wavy boundary. (0 to 3 inches thick)
2Cd--23 to 60 inches; light yellowish brown (2.5Y 6/4) dense compact glacial till that breaks to very gravelly loam, light gray (2.5Y 7/2) dry; massive; extremely hard, very firm, nonsticky, nonplastic, weakly smeary; 40 percent pebbles; NaF pH l0.5; very strongly acid (pH 5.0).
TYPE LOCATION: Whatcom County, Washington; about 8 miles southeast of Van Zandt; l,700 feet south and l,700 feet east of the northwest corner of sec. 4, T. 37 N., R. 6 E.
RANGE IN CHARACTERISTICS: Mean annual soil temperature is 4l to 45 degrees F. Depth to a paralithic contact with dense compact glacial till ranges from l4 to 20 inches. The control section averages from 40 to 60 percent dunite fragments and includes 5 to l0 percent cobbles.
The E horizon has hue of 7.5YR or l0YR, value of 3 through 5
moist and 5 through 7 dry, and chroma of 2 or 3 moist and dry.
The Bs horizon has hue of 5YR or 7.5YR, value of 3 through 5
moist and 4 through 6 dry, and chroma of 4 through 6 moist and 6 through 8 dry. It is very gravelly loam or very gravelly silt loam. Reaction is strongly acid or very strongly acid.
The 2Cd horizon is dense, compact glacial till that has hue of 2.5Y or 5Y, value of 4 through 6 moist, 4 through 7 dry, and chroma of 2 through 4 moist and l through 4 dry. The till breaks to very gravelly loam, very gravelly sandy loam or very gravelly loamy sand.
COMPETING SERIES: This is the Clendenen series in another family. The Clendenen series lacks dunite fragments in the particle-size control section, and have more than 6 percent organic carbon in the upper 10 cm of the spodic horizon.
GEOGRAPHIC SETTING: Edfro soils are on glacially modified mountain shoulder slopes at elevations of 2,400 to 3,600 feet. The soils in formed a mixture of volcanic ash, loess, and colluvium, and alpine glacial till derived dominately from dunite. Edfro soils are in a marine climate with cool dry summers and cold wet winters. Snow cover lasts from November through May. Mean annual precipitation is 90 to l05 inches. Mean January temperature is about 29 degrees F; mean July temperature is about 57 degrees F. Mean annual temperature is about 42 degrees F. The frost-free season is 85 to l05 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are Hinker, Klawatti, and Twinsi soils. Hinker and Klawatti soils are moderately deep to a lithic contact. Twinsi soils are moderately deep to a paralithic contact of dense glacial till.
DRAINAGE AND PERMEABILITY: Moderately well drained; medium runoff; moderate permeability to the dense glacial till and very slow through it. A perched water table is as high as l to l.5 feet from December through April.
USE AND VEGETATION: Used for timber production, watershed, and wildlife habitat. Native vegetation is Pacific silver fir, western hemlock, Alaska-cedar, and mountain hemlock with an undergrowth of bunchberry dogwood, blue-leaved huckleberry, western brackenfern, deer fern and northern twinflower.
DISTRIBUTION AND EXTENT: Northwestern Washington, Twin Sisters Mountain area. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Whatcom County, Washington, l983.
REMARKS: Partial laboratory data are available for a taxadjunct of this soil. National Soil Survey lab numbers 80T7283 and 80T7284.
Diagnostic horizons and features recognized in this soil are:
An albic horizon - from 4 to 7 inches (E horizon)
A spodic horizon - from 4 to 23 inches (Bs1, Bs2 and Bs3 horizons)
A densic contact at 23 inches (Cd layer)
40 to 60 percent dunite fragments in the particle-size control section
Classification revised 3/2001 based on changes to Soil Taxonomy.
Depths to diagnostics features and horizons are measured from the top of the first mineral layer.