LOCATION SOOSAP OREstablished Series
TAXONOMIC CLASS: Medial, amorphic Typic Haplocryands
TYPICAL PEDON: Soosap loam - forested. (Colors are for moist soil unless otherwise noted.)
Oi--1 inch to 0; partially decomposed needles, leaves, and twigs.
A1--0 to 6 inches; very dark brown (10YR 2/2) gravelly loam, dark grayish brown (10YR 4/2) dry; moderate fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; slightly smeary; many very fine, fine, and medium roots; many irregular pores; 15 percent gravel; very strongly acid (pH 5.0); clear smooth boundary.
A2--6 to 13 inches; very dark brown (10YR 2/2) loam, dark grayish brown (10YR 4/2) dry; weak fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; slightly smeary; many very fine, fine, and medium roots; many irregular pores; 10 percent gravel; strongly acid (pH 5.4); clear smooth boundary. (Combined thickness of the A horizon is 7 to 25 inches)
Bw1--13 to 21 inches; very dark grayish brown (10YR 3/2) loam, brown (10YR 4/3) dry; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; slightly smeary; many very fine and fine roots; many very fine tubular pores; 10 percent gravel; strongly acid (pH 5.4); clear smooth boundary.
Bw2--21 to 35 inches; very dark brown (10YR 3/2) loam, brown (10YR 4/3) dry; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; slightly smeary; common very fine and fine roots; many very fine tubular pores; 10 percent gravel; strongly acid (pH 5.2); clear smooth boundary. (Combined thickness of the Bw horizon is 13 to 25 inches)
Cr--35 to 44 inches; very soft weathered tuff.
R--44 inches; tuffaceous rock.
TYPE LOCATION: Clackamas County, Oregon, about 21/2 miles west of Cougar Lake; in the NE1/4SE1/4NW1/4, section 15, T. 6 S., R. 4 E.
RANGE IN CHARACTERISTICS: The soil is usually moist but is dry for less than 45 consecutive days between depths of 4 and 12 inches during the summer months. The mean annual soil temperature is 42 to 46 degrees F. The mean summer soil temperature is less than 47 degrees F. with an O horizon and in full shade. Depth to soft bedrock is 20 to 40 inches. Rock fragments range from 10 to 20 percent in the particle-size control section. The fine-earth fraction of the particle-size control section contains greater than 85 percent phosphate retention, acid oxalate extractable aluminum plus one-half iron of more than 2.0 percent, and 15 to 30 percent 15-bar moisture based on an air-dried sample. Moist bulk density is 0.80 to 0.90 grams per cubic centimeter. It is very strongly acid or strongly acid. Hue is 10YR or 7.5YR. The apparent clay content is 10 to 18 percent.
The A horizon has value 2 or 3 moist and 3 or 4 dry. It is gravelly loam with 10 to 20 percent gravel and 0 to 5 percent cobbles.
The Bw horizon has value of 3 or 4 moist, 4 through 6 dry, and chroma of 2 through 4 moist and dry. It is loam, silt loam, or cobbly loam with 0 to 10 percent gravel and 0 to 10 percent cobbles.
The Cr horizon has color similar to the Bw horizon.
COMPETING SERIES: These are the Cruiser, Keel, and Oneonta series. Cruiser soils are 40 to more than 60 inches to bedrock with an average of 20 to 30 percent clay in the particle-size control section. Keel soils are 20 to 40 inches to a lithic contact, average more than 18 percent clay in the particle-size control section and have a moist bulk density of less than 0.85 grams per cubic centimeter. Oneonta soils are 40 to more than 60 inches to bedrock.
GEOGRAPHIC SETTING: Soosap soils are on ridgetops and in saddles on mountains. Elevation is 2800 to 4800 feet. Slopes are 5 to 30 percent. The soils formed in colluvium weathered from tuffs, breccias, and andesite mixed with volcanic ash. The climate is characterized by cold wet winters and cool moist summers. The mean annual precipitation is 65 to 100 inches. The mean annual temperature is 40 to 44 degrees F. The frost-free period is 30 to 90 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Highcamp and Kinzel series. Kinzel soils are deeper than 40 inches to bedrock. Highcamp soils are medial-skeletal and have an ochric epipedon.
DRAINAGE AND PERMEABILITY: Well drained; moderate permeability.
USE AND VEGETATION: Soosap soils are used for timber production, wildlife habitat, and recreation. Native vegetation consists of Douglas fir, noble fir, mountain hemlock, vine maple, Oregongrape, salal, Pacific rhododendron, red huckleberry, tall blue huckleberry, and common bear grass.
DISTRIBUTION AND EXTENT: Western slope of the Cascade Mountains in northwestern Oregon; MLRA 3. The series is moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Clackamas County, Oregon, 1982.
REMARKS: This draft represents a change in classification from Medial Andic Cryumbrepts based on the Andisol Order.
Diagnostic horizons and features recognized in this pedon:
Umbric epipedon - from 0 to 35 inches (A1, A2, Bw1, and Bw2 horizons) with a weighted average of less than 10 percent organic matter (6 percent organic carbon)
Particle-size control section - from 0 to 35 inches (A1, A2, Bw1, and Bw2 horizons)
Andic soil properties - from 0 to 35 inches