LOCATION FERNWOOD                OR

Established Series
Rev. KLS/GLG/RWL
06/2011

FERNWOOD SERIES

The Fernwood series consists of moderately deep, well drained soils that formed in mixed volcanic ash and colluvium weathered from andesite and basalt. Fernwood soils are on mountainous uplands and have slopes of 5 to 90 percent. The mean annual precipitation is about 70 inches and the mean annual temperature is about 43 degrees F.

TAXONOMIC CLASS: Loamy-skeletal, isotic, frigid Andic Humudepts

TYPICAL PEDON: Fernwood very gravelly loam, forested. (Colors are for moist soil unless otherwise stated.)

Oi--0 to 1 inch; slightly decomposed needles, leaves, and twigs.

A1--1 to 5 inches; black (10YR 2/1) very gravelly loam, dark brown (10YR 3/3) dry; moderate fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; weakly smeary; many very fine, fine and coarse roots; many irregular pores; 35 percent gravel and 15 percent cobbles; strongly acid (pH 5.4); clear smooth boundary. (3 to 6 inches thick)

A2--5 to 11 inches; very dark grayish brown (10YR 3/2) very gravelly loam, brown (10YR 4/3) dry; moderate fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; weakly smeary; many very fine, fine and coarse roots; many very fine tubular pores; 30 percent gravel and 10 percent cobbles; strongly acid (pH 5.2); clear wavy boundary. (5 to 12 inches thick)

Bw1--11 to 18 inches; brown (10YR 4/3) very cobbly loam, brown (10YR 5/3) dry; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; weakly smeary; common very fine and fine and few medium roots; many very fine tubular pores; 40 percent cobbles and 10 percent gravel; strongly acid (pH 5.2); gradual wavy boundary. (4 to 12 inches thick)

Bw2--18 to 26 inches; brown (10YR 4/3) very cobbly loam, pale brown (10YR 6/3) dry; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; weakly smeary; few fine and medium roots; many very fine tubular pores; 50 percent cobbles and 10 percent gravel; strongly acid (pH 5.2); clear wavy boundary. (5 to 13 inches thick)

R--26 inches; fractured andesite.

TYPE LOCATION: Clackamas County, Oregon; about 6 miles west of Table Rock; in the NW1/4NE1/4NE1/4, section 9, T. 7 S., R. 3 E.

RANGE IN CHARACTERISTICS: The soil is usually moist but is dry for less than 45 consecutive days throughout the moisture control section during the summer. The mean annual soil temperature is 43 to 47 degrees F. The mean summer soil temperature is less than 47 degrees F. The solum is estimated to have acid oxalate extractable aluminum plus one-half iron of 1.0 to 2.0 percent and less than 2.0 cmol per kg fine earth of 1N KCL extractable aluminum. It has 35 to 75 percent rock fragments. Depth to bedrock is 20 to 40 inches. It is strongly acid to moderately acid. Moist bulk density is 0.85 to 0.95 grams per cubic centimeter throughout. The umbric epipedon is 10 to 18 inches thick.

The A horizon has hue of 10YR, 7.5YR or 5YR, value of 2 or 3 moist, 3 through 5 dry, and chroma of 1 through 3 moist and dry. It is loam or silt loam. Rock fragments range from 20 to 35 percent gravel and 5 to 25 percent cobbles.

The Bw horizon has hue of 10YR, 7.5YR or 5YR, value of 3 or 4 moist, 4 or 5 dry, and chroma of 2 through 4 moist and dry. It is loam, silt loam, or clay loam with 18 to 30 percent clay. Rock fragments range from 10 to 25 percent gravel and 25 to 50 percent cobbles.

COMPETING SERIES: These are the Tinker and Zygore soils. Tinker soils are 20 to 40 inches deep to a cemented or compacted C1 horizon and are more than 60 inches deep to bedrock. Zygore soils are more than 60 inches deep to bedrock and average less than 18 percent clay in the control section.

GEOGRAPHIC SETTING: Fernwood soils are on mountains at elevations of 1,800 to 3,000 feet. Slopes range from 5 to 90 percent. The soils formed in mixed ash and colluvium weathered from andesite and basalt. The climate is characterized by cool wet winters and warm moist summers. The mean annual temperature is 40 to 45 degrees F. The mean annual precipitation is 60 to 90 inches. The frost-free period is 45 to 110 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Wilhoit and the competing Zygore soils. Wilhoit soils have less than 35 percent rock fragments in the control section and are deep.

DRAINAGE AND PERMEABILITY: Well drained; moderately rapid permeability.

USE AND VEGETATION: Fernwood soils are used for timber production, wildlife habitat, and recreation. Native vegetation is Douglas-fir, western hemlock, vine maple, Oregon-grape, salal, red huckleberry, western swordfern and brackenfern.

DISTRIBUTION AND EXTENT: Western slopes 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: Diagnostic horizons and features recognized in this pedon:

Umbric epipedon - from 1 to 11 inches (A1 and A2 horizons)

Cambic horizon - from 11 to 26 inches (Bw1 and Bw2 horizons)

Andic feature - from 1 to 26 inches having moist bulk density of 0.85 to 0.95 grams per cubic centimeter and estimated acid oxalate extractable aluminum of 1.0 to 2.0 percent.

Particle-size control section - from 10 to 25 inches (Bw1 and Bw2 horizons) with a weighted average of 55 percent rock fragments.

All depths to diagnostic horizons and other features are measured from the to of the first mineral horizon.

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National Cooperative Soil Survey
U.S.A.