LOCATION ASCHOFF OR+WAEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, isotic, mesic Andic Dystrudepts
TYPICAL PEDON: Aschoff cobbly medial loam, forested. (Colors are for moist soil unless otherwise noted.)
Oi-0 to 3 inches; needles, twigs, cones, bar, etc; partially decomposed in the lower part.
Oe-3 to 4 inches; black (10YR 2/1) amorphous organic matter; abrupt smooth boundary.
A--4 to 10 inches; dark brown (7.5YR 3/2) cobbly medial loam, brown (7.5YR 4/2) dry; moderate fine and very fine subangular blocky structure; ped surfaces are very dark brown (10YR 2/2); slightly hard, friable, slightly sticky and slightly plastic; many roots; many very fine and fine irregular and tubular pores; 15 percent cobbles and 15 percent gravel ; moderately acid (pH 5.7); clear wavy boundary. (3 to 10 inches thick)
AB--10 to 16 inches; dark brown (7.5YR 3/3) cobbly medial loam, brown (7.5YR 4/3) dry; moderate fine and very fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many roots; many very fine and fine irregular and tubular pores; 15 percent cobbles and 15 percent gravel; moderately acid (pH 5.8); clear wavy boundary. (0 to 12 inches thick)
Bw--16 to 27 inches; dark brown (7.5YR 3/4) very cobbly loam, brown (7.5YR 4/4) dry; moderate fine and very fine subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common roots; many very fine and fine irregular and tubular pores; 25 percent cobbles, 15 percent gravel and 10 percent stones; moderately acid (pH 5.9); gradual wavy boundary. (6 to 18 inches thick)
BC--27 to 38 inches; dark brown (7.5YR 3/4) very cobbly loam, brown (7.5YR 4/4) dry; weak very fine and fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common roots; many very fine and fine irregular and tubular pores; 25 percent cobbles, 20 percent gravel and 10 percent stones; moderately acid (pH 6.0); gradual wavy boundary. (6 to 18 inches thick)
C--38 to 64 inches; brown (7.5YR 4/4) very cobbly loam, brown (7.5YR 5/4) dry; massive; slightly hard, friable, slightly sticky and slightly plastic; common roots; many very fine and fine irregular and tubular pores; 30 percent cobbles, 5 percent stones, 20 percent gravel; slightly acid (pH 6.2).
TYPE LOCATION: Multnomah County, Oregon; along the Cougar Creek road; NW1/4 NW1/4 section 17, T. 1 S., R. 6 E., W. M.
RANGE IN CHARACTERISTICS: The mean annual soil temperature ranges from 47 to 55 degrees F. The soils have a udic moisture regime but they have a short dry period of less than 45 consecutive days during the summer. Thickness of the solum ranges from 30 to 60 inches. Depth to bedrock is mostly 60 inches or more but ranges to 48 inches. Rock fragments in the 10 to 40 inch control section range from 35 to 70 percent. Cobbles or gravel are dominant; stones range from 0 to 10 percent. The thickness of the umbric epipedon ranges from 10 to 20 inches. The soils are slightly to strongly acid. Moist bulk density is 0.85 to 0.95 grams per cubic centimeter throughout. Organic matter is 6 to 12 percent in the upper 12 inches of the solum.
The A horizon has hue of 10YR or 7.5YR, value of 2 or 3 moist, 4 or 5 dry, and chroma of 1, 2 or 3 moist and dry. It is cobbly medial silt loam, cobbly medial loam, or very gravelly medial loam. It is estimated to have acid oxalate extractable aluminum plus one-half iron of 1.0 to 3.0 percent and less than 2.0 cmol per kg fine earth of 1N KCL extractable aluminum, volcanic glass content of 5 to 30 percent, and phosphate retention of 75 to 85 percent.
The Bw horizon has hue of 10YR or 7.5YR, value of 3 or 4 moist, 4, 5 or 6 dry, and chroma of 3 or 4 moist and dry. It is loam or silt loam with 10 to 27 percent clay. It is very cobbly or very gravelly with 15 to 40 percent gravel and 15 to 45 percent cobbles.
The C horizon has range in characteristics similar to that of the Bw horizon except for being massive and having a dry value of 5 through 7. Rock fragments increase with increasing depth and range from 50 to 80 percent.
COMPETING SERIES: This is the Hoodview series. Hoodview soils have an umbric epipedon thicker than 20 inches.
GEOGRAPHIC SETTING: Aschoff soils are on hill slopes in glaciated valleys in mountainous areas at elevations of 100 to 2,800 feet. Slopes range from 5 to 90 percent. The soils formed in medium textured glacial till derived mostly from rocks of the Cascade andesite formation. The climate is characterized by warm wet winters and hot moist summers. The mean annual precipitation is 60 to 115 inches. The mean annual temperature is 45 to 54 degrees F., the mean January temperature is 35 degrees F., the mean July temperature is 63 degrees F. The frost-free period is 100 to 200 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bull Run, Headly and Sahalie soils and the competing Hoodview soils. Bull Run soils lack rock fragments and are dominated by pyroclastic materials. Headly soils have an ochric epipedon and lack rock fragments in the 10- to 40-inch control section. Sahalie soils have an ochric epipedon, have thickness of sola ranging from 10 to 24 inches, and have firm and hard C horizons.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: These soils are used mainly for timber production, watershed, recreation and wildlife habitat. Overstory vegetation is mostly Douglas fir, western hemlock , western red alder; understory vegetation is oxalis, salal, swordfern, and vine maple.
DISTRIBUTION AND EXTENT: Cascade Mountains in northwestern Oregon an southwestern Washington; MLRA 3.. The series is of moderate extent.
MLRA OFFICE RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Multnomah County, Oregon, 1975.
REMARKS: Classification changed 6/98 based on 1998 Keys to Soil Taxonomy. Competing series have not been revised.
Diagnostic horizons and features recognized in this pedon:
Umbric epipedon - from 4 to 16 inches (A and AB horizons)
Cambic Horizon - from 16 to 27 inches (Bw horizon)
Andic feature - from 4 to 16 inches having a moist bulk density of 0.85 to 0.95 grams per cubic centimeter and an estimated acid oxalate extractable aluminum plus one-half iron of 1.0 to 2.0 percent.
Particle-size control section - from 14 to 44 inches (lower 2 inches of AB horizon, Bw, BC, and upper 6 inches of C horizon) with a weighted average of 51 percent rock fragments.
ADDITIONAL DATA ON ANDIC SOIL PROPERTIES IS NEEDED ON THIS SERIES TO CONFIRM CLASSIFICATION OF ANDIC SUBGROUP OR ANDISOL. ALSO THE FRIGID COUNTERPART OF THIS SOIL CALLED ZYGORE SHOULD BE FURTHER INVESTIGATED.
ADDITIONAL DATA: Partial characterization data on 3 profiles (FS63Oreg-045-32(1-6), FS63Oreg-045-31(1-6), and FS62Oreg-045-11(1-6) by the Oregon State University. Unpublished.