LOCATION DELPHI WAEstablished Series
TAXONOMIC CLASS: Medial-skeletal, mixed, mesic Humic Haploxerands
TYPICAL PEDON: Delphi very gravelly loam, forested. (Colors are for moist soils unless otherwise noted.
Oi--2 to 1 inch; needles, leaves, wood, bark.
Oa--1 inch to 0; partially decomposed needles, wood, and bark.
A--0 to 8 inches; dark reddish brown (5YR 3/3) very gravelly loam, dark brown (10YR 4/3) dry; weak fine granular structure; soft, very friable, nonsticky and nonplastic; weakly smeary; many coarse, medium, and fine roots; NaF pH 10.5; 40 percent rounded pebbles includes 20 percent shot-size concretions; medium acid (pH 5.8); clear smooth boundary. (7 to 9 inches thick)
AB--8 to 13 inches; dark brown (7.5YR 3/2) very gravelly loam, brown (10YR 5/3) dry; weak fine granular structure; soft, very friable, nonsticky and nonplastic; weakly smeary; many coarse and medium fine roots; NaF pH 10.5; 40 percent rounded pebbles; medium acid (pH 5.6); clear smooth boundary. (3 to 6 inches thick)
Bwl--13 to 31 inches; dark yellowish brown (10YR 4/4) very gravelly silt loam, light yellowish brown (10YR 6/4) dry; moderate fine subangular blocky structure; soft, friable, slightly sticky and slightly plastic; weakly smeary; common medium and fine roots; NaF pH 11.0; 40 percent rounded pebbles; strongly acid (pH 5.4); clear smooth boundary. (14 to 20 inches thick)
Bw2--31 to 48 inches; dark yellowish brown (10YR 4/4) extremely gravelly silt loam, light yellowish brown (10YR 6/4) dry; moderate fine subangular blocky structure; soft, friable, slightly sticky and slightly plastic; few fine roots; 60 percent rounded pebbles; strongly acid (pH 5.4); clear smooth boundary. (14 to 20 inches thick)
2Bqm--48 to 60 inches; dark yellowish brown (10YR 4/4) extremely gravelly clay loam, yellowish brown (10 YR 5/4) dry; massive, very hard, very firm, weakly cemented; 70 percent rounded pebbles; strongly acid (pH 5.4)
TYPE LOCATION: Thurston County, Washington; 11 miles west of Olympia, about 1,700 feet west and 1,400 feet south of the N.E.
c.rner of sec. 17, T, 18 N., R. 3 W., W.M.
RANGE IN CHARACTERISTICS: Depth to cemented till ranges from 40 to 55 inches. The mean annual soil temperature is 47 to 52 degrees F. These soils are usually moist but are dry in the moisture control section for 45 to 60 consecutive days following summer solstice in 7 years out of 10. The control section is silt loam or loam modified by 35 to 70 rock fragments.
The A and AB horizons have hue of 5YR or 7.5 YR moist and 7.5YR or 10 YR dry, value of 4 or 5 dry, chroma of 2 or 3 moist and dry. The AB horizon is very gravelly sit loam or very gravelly loam. The A horizons are medium acid or strongly acid.
The Bw horizon has hue of 7.5YR or 10YR moist and value of 4 through 6 dry. it is very gravelly sit loam, very gravelly loam, extremely gravelly loam or extremely gravelly silt loam.
The 2Bqm horizon is compact and weakly cemented extremely gravelly clay loam or extremely gravelly loam in the upper few feet and extremely gravelly loamy sand in the lower part.
COMPETING SERIES: These are the McCarthy, McElroy, Schneider and Washougal series. McCarthy soils have a paralithic contact at depths of 20 to 40 inches. McElroy soils are dry for 60 to 75 days in the moisture control section. Schneider soils are slightly acid or medium acid in the B horizon. Washougal soils have a very gravelly or very cobbly sand 2C horizon in the lower part of the particle-size control section.
GEOGRAPHIC SETTING: These soils are on glacial uplands at elevations from 50 to 1000 feet. They formed in glacial till. Slopes range from 3 to 30 percent. Delphi soils are in a marine climate with average annual precipitation of 50 to 75 inches. The mean January temperature is about 38 degrees F., mean July temperature is 63 degrees F. The mean annual temperature is about 50 degrees F. The frost-free season is 165 to 195 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Grove soils and the competing Schneider soils. Grove soils are sandy-skeletal.
DRAINAGE AND PERMEABILITY: Well drained, slow to medium runoff; moderate permeability.
USE AND VEGETATION: Used for timber production. Native vegetation is mainly Douglas-fir, western hemlock and some red alder and western redcedar. Understory is Cascade, Oregon-grape, salal, red huckleberry, western swordfern, western brackenfern, vine maple and salmonberry.
DISTRIBUTION AND EXTENT: In Mason and Thurston Counties in western Washington. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Thurston County, Washington, 1941.
REMARKS: Classification only changed 4/94 because of recent amendments to Soil Taxonomy. Has andic properties throughout.