LOCATION CASCADE OREstablished Series
TAXONOMIC CLASS: Fine-silty, mixed, superactive, mesic Humic Fragixerepts
TYPICAL PEDON: Cascade silt loam, woodland. (Colors are for moist soil unless otherwise noted.)
A--0 to 8 inches; dark brown (7.5YR 3/2) silt loam, brown (10YR 5/3) dry; strong fine granular and very fine subangular blocky structure; friable, slightly sticky and slightly plastic; many very fine and few fine to coarse roots; many very fine pores; 10 percent fine concretions; 10 percent gravel; moderately acid (pH 6.0); clear smooth boundary. (5 to 10 inches thick)
Bw1--8 to 16 inches; dark brown (10YR 3/3) silt loam, brown (10YR 5/3) dry; moderate fine subangular blocky structure; friable, slightly hard, slightly sticky and slightly plastic; common very fine roots; many very fine pores; 5 percent fine concretions; moderately acid (pH 5.9); clear wavy boundary. (5 to 9 inches thick)
Bw2--16 to 27 inches; dark brown (7.5YR 3/4) silt loam, brown (7.5YR 5/4) dry; moderate fine subangular blocky structure; friable, slightly hard, slightly sticky and slightly plastic; few fine and coarse roots; many very fine pores; common fine concretions and very firm peds; moderately acid (pH 5.6); clear wavy boundary. (6 to 12 inches thick)
2Bx--27 to 35 inches; dark brown (7.5YR 4/4) silt loam, light yellowish brown (10YR 6/4) dry; 10 percent brown (7.5YR 5/2) silt loam tongues with strong brown (7.5YR 5/6) redox features at the margins; weak coarse prismatic structure parting to moderate fine subangular blocky; firm, brittle, hard, slightly sticky and moderately plastic; few fine and medium roots; many very fine pores; few fine concretions; few fine black stains; strongly acid (pH 5.3); clear wavy boundary. (6 to 10 inches thick)
2Btx1--35 to 45 inches; dark brown (10YR 4/3) silt loam, light yellowish brown (10YR 6/4) dry; 20 percent brown (7.5YR 5/2) tongues with brown and strong brown (7.5YR 5/4 and 5/6) redox features at the margins; weak coarse prismatic and weak medium blocky structure; very firm brittle, very hard, slightly sticky and moderately plastic; few very fine roots; few very fine pores; few faint and distinct clay films in pores and on faces of peds; common medium and coarse black stains; strongly acid (pH 5.3); clear irregular boundary. (5 to 15 inches thick)
2Btx2--45 to 60 inches; dark brown (10YR 4/3) silt loam, light yellowish brown (10YR 6/4) dry; 10 percent brown (7.5YR 5/2) tongues with brown and strong brown (7.5YR 5/4 and 5/6) redox features at the margins; weak coarse prismatic structure; very firm, brittle, very hard, slightly sticky and slightly plastic; few very fine pores; few faint and distinct clay films on faces of peds; few fine black stains; moderately acid (pH 5.8).
TYPE LOCATION: Multnomah County, Oregon; 7 miles northwest of Portland and about 25 feet north of Skyline Blvd; SW1/4 SE1/4 NE1/4 section 10, T. 2 N., R. 2 W.
RANGE IN CHARACTERISTICS: The profiles are usually moist but are dry throughout between depths of 4 and 12 inches for about 45 to 60 consecutive days during the summer. The mean annual soil temperature ranges from 52 to 56 degrees F. The thickness of the solum and depth to the fragipan range from 20 to 30 inches. There is a perched water table over the fragipan during the winter. The umbric epipedon ranges in thickness from 10 to 19 inches. Very stony silty clay loam textures occur below 30 inches in some areas. Soil reaction ranges from strongly or moderately acid throughout the solum.
The A horizon has hue of 7.5YR or 10YR and chroma of 2 or 3 moist.
The Bw horizon has hue of 10YR or 7.5YR, value of 3 or 4 moist, 5 or 6 dry and chroma of 3 or 4 moist and dry. It is silt loam or silty clay loam with 18 to 30 percent clay and less than 10 percent coarser than very fine sand.
The fragipan (Bx and Btx) has redox features and tongues with chroma of 2 or less and ranges from 2 to over 4 feet thick. It is silt loam or silty clay loam, firm or very firm and hard or very hard. Clay films are few or common and faint or distinct on the fractures and in pores in the fragipan. Few rock fragments of basalt are at or near the upper boundary of the fragipan. In some areas a buried strong silty clay loam occurs below 30 inches.
COMPETING SERIES: These are the Bornstedt, Delena, Goble, Kinton and Powell series in a similar family. Bornstedt soils have ochric epipedons and heavy silty clay loam B horizons and clayey fragipans with less than 35 percent base saturation. Delena soils have an aquic moisture regime. Goble soils have a udic moisture regime, have evidence of amorphous clays and are 30 to 45 inches deep to the fragipan. Kinton soils have ochric epipedons and lack mottles above depth of 30 inches.
GEOGRAPHIC SETTING: The Cascade soils are on smooth or rolling, convex, long slopes and ridgetops at elevations of 250 to 1,400 feet. Slopes range from 3 to 60 percent. The soils formed in loess-like materials. The climate is humid temperate with cool moist winters and warm dry summers. The mean July temperature is 67 degrees F., mean January temperature is 39 degrees F., and mean annual temperature is 50 to 54 degrees F. Mean annual precipitation is 50 to 60 inches. Frost-free period is 165 to 210 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Goble, Kinton and Delena soils and the Helvetia soils. Helvetia soils have argillic horizons and lack fragipans.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; slow to rapid runoff; slow permeability.
USE AND VEGETATION: Small grain, grass seed, hay, pasture, some berries and woodland. Native vegetation is Douglas-fir, big leaf maple, salal, red huckleberry, vine maple, swordfern, grasses and weeds.
DISTRIBUTION AND EXTENT: Northwestern Oregon; MLRA 2. The soil is extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Multnomah County, Oregon, 1919.
REMARKS: Diagnostic horizons and other features:
Umbric epipedon - from 0 to 16 inches
Fragipan - from 27 to 60 inches
Cambic horizon - from 16 to 27 inches
ADDITIONAL DATA: Characterization data on two profiles (S70 Oreg-26-6, 7) reported in Riverside Soil Survey Laboratory computer printouts for soils sampled in Multnomah, Clackamas and Washington Counties, Oregon, 1971. Percent clay in the control section based on 15-bar water values of about 9 to 13 percent.