LOCATION OLYIC OR+WAEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, active, mesic Typic Haplohumults
TYPICAL PEDON: Olyic silt loam, woodland. (Colors are for moist soil unless otherwise noted.)
O1--1/4 inch to 0; needles, leaves, twigs.
A1--0 to 8 inches; dark reddish brown (5YR 2/2) silt loam, dark brown (7.5YR 4/2) dry; strong fine granular structure; soft, friable, slightly sticky and slightly plastic; many fine medium roots; many very fine pores; many fine concretions; medium acid (pH 5.6); clear smooth boundary. (6 to 10 inches thick)
A3--8 to 13 inches; dark reddish brown (5YR 3/3) silt loam, dark brown (7.5YR 5/4) dry; strong fine granular structure; soft, friable, slightly sticky and slightly plastic; many fine and few medium roots; many very fine pores; common fine concretions; strongly acid (pH 5.4); clear smooth boundary. (0 to 7 inches thick)
B1--13 to 20 inches; dark reddish brown (5YR 3/4) silty clay loam, brown (7.5YR 5/4) dry; moderate fine subangular blocky structure; slightly hard, friable, sticky and plastic; common fine and few large roots; many fine pores; few thin clay films in some pores; strongly acid (pH 5.4); clear smooth boundary. (0 to 10 inches thick)
B21t--20 to 33 inches; dark reddish brown (5YR 3/4) silty clay loam, brown (7.5YR 5/4) dry; moderate fine subangular blocky structure; slightly hard, firm, sticky and plastic; few fine roots; many very fine pebbles; very strongly acid (pH 4.8); clear smooth boundary. (12 to 15 inches thick)
B22t--33 to 42 inches; dark reddish brown (5YR 3/4) silty clay loam, strong brown (7.5YR 5/6) dry; weak fine subangular blocky structure; hard, firm, sticky and very plastic; few fine roots; common fine pores; 5 percent basalt pebbles; very strongly acid (pH 4.8); clear irregular boundary. (8 to 14 inches thick)
R--42 inches; fractured basalt.
TYPE LOCATION: Yamhill County, Oregon; about 60 feet below the High Heaven road, NW1/4 NE1/4 SW1/4 section 32, T.3S., R.5W.
RANGE IN CHARACTERISTICS: The mean annual soil temperature ranges from 49 degrees to 54 degrees F. The soils are usually moist and are dry for less than 45 days in the control section during the summer. Depth to bedrock is 40 to 60 inches or more.
The A horizon has hue of 7.5YR or 5YR, value of 2 or 3 moist, 3 to 5 dry and chroma of 2 or 3 moist and 2 through 4 dry. It commonly is silt loam but ranges to loam and clay loam in some pedons. This horizon has strong or moderate granular structure. It has 10 to 15 percent concretions and small pebbles. It is strongly to medium acid.
The Bt horizon has hue of 7.5YR or 5YR value of 3 or 4 moist and chroma of 4 through 6 moist and dry. It is silty clay loam or clay loam and has 27 to 35 percent clay and more than 15 percent coarser than very fine sand. This horizon has few to common thin clay films. It averages 5 to 25 percent gravel. It is strongly to very strongly acid.
The horizons below depth of 36 inches have up to 60 percent rock fragments in some pedons.
COMPETING SERIES: These are the Honeygrove, Jory, McGowan, Nekia, Olympic and Peavine series. Honeygrove, Jory, Nekia, Olympic and Peavine soils have fine-textured argillic horizons. Also, Peavine soils have a paralithic contact at depths of 20 to 40 inches; Jory, Nekia and Olympic soils have xeric moisture regimes. McGowan soils have slightly acid B horizons.
GEOGRAPHIC SETTING: The Olyic soils are on rolling, hilly to steep uplands in the Coast Range at elevations of 500 to 2,000 feet. Slopes range from 0 to 90 percent. The soils formed in residuum and colluvium weathered from basalt. The climate is subhumid with cool, moist winters and cool dry summers. The average annual precipitation is about 60 to 90 inches. Average July temperature is 64 degrees F., average January temperature is 34 degrees F., and the average annual temperature is 47 degrees to 52 degrees F. The frost-free season is 145 to 200 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Melby soils and the competing Peavine soils. Melby soils have 7.5YR hue, are fine textured, lack argillic horizons, and formed over siltstone.
DRAINAGE AND PERMEABILITY: Well drained; slow to rapid runoff; moderate permeability.
USE AND VEGETATION: Used mainly for timber production. Other uses are pasture, recreation, wildlife, and water supply. Native vegetation is Douglas-fir, western hemlock, bigleaf maple, alder, vine maple, dwarf Oregon grape, salal, and swordfern.
DISTRIBUTION AND EXTENT: The eastern slopes of the Coast Range in northwestern Oregon and SW Washington. The series is extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Yamhill County, Oregon, 1974.