LOCATION SCAPONIA OR

Established Series
Rev. RWL-GLG-AON
06/2011

SCAPONIA SERIES

The Scaponia series consists of deep, well drained soils that formed in colluvium weathered from siltstone. Scaponia soils are on mountains and have slopes of 0 to 90 percent. Mean annual precipitation is about 65 inches and the mean annual temperature is about 49 degrees F.

TAXONOMIC CLASS: Fine-loamy, isotic, mesic Humic Dystrudepts

TYPICAL PEDON: Scaponia silt loam, wooded. (Colors are for moist soil unless otherwise noted.)

Oi--0 to 2 inches; slightly decomposed litter of leaves, twigs, moss and woody materials.

A--2 to 9 inches; dark brown (10YR 3/3) silt loam, brown (10YR 5/3) dry; moderate fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine roots; many very fine irregular pores; 10 percent 2 to 5 millimeter siltstone paragravel; moderately acid (pH 6.0); clear smooth boundary. (7 to 9 inches thick)

Bw1--9 to 21 inches; brown (10YR 4/3) paragravelly silt loam, pale brown (10YR 6/3) dry; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many fine roots; many very fine tubular pores; 20 percent siltstone paragravel and 5 percent siltstone paracobbles; strongly acid (pH 5.4); gradual wavy boundary. (10 to 15 inches thick)

Bw2--21 to 34 inches; dark yellowish brown (10YR 4/4) very paragravelly silt loam, light yellowish brown (10YR 6/4) dry; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many fine roots; many very fine tubular pores; 30 percent siltstone paragravel and 5 percent siltstone paracobbles; strongly acid (pH 5.2); gradual wavy boundary. (10 to 15 inches thick)

C--34 to 44 inches; brown (10YR 4/3) extremely paracobbly silt loam, light yellowish brown (10YR 6/4) dry; massive; slightly hard, friable, slightly sticky and plastic; common fine roots; many very fine tubular pores; 30 percent siltstone paragravel and 40 percent siltstone paracobbles; strongly acid (pH 5.2); gradual wavy boundary. (10 to 21 inches thick)

Cr--44 to 62 inches; fractured partially weathered siltstone.

TYPE LOCATION: Columbia County, Oregon; Gunner's Lake Road 130 in the northwest 1/4 southwest 1/4 northeast 1/4, sec. 22, T. 4 N., R. 3 W.

RANGE IN CHARACTERISTICS: The soil is usually moist but is dry for a short period of less than 45 consecutive days between depths of 4 to 12 inches during the summer. The mean annual soil temperature is 47 to 54 degrees F. Depth to paralithic contact is 40 to 60 inches. The particle-size control section is silt loam or loam and is 18 to 27 percent clay, more than 15 percent fine sand and coarser, and more than 35 percent pararock fragments.

The A horizon has value of 2 or 3 moist, 4 or 5 dry, and chroma of 2 or 3 moist and dry. It is 12 to 18 percent clay and 5 to 15 percent siltstone paragravel. It is very strongly acid to moderately acid.

The Bw horizon has hue of 10YR or 7.5YR, value of 5 or 6 dry, 4 or 5 moist and chroma of 3 or 4 moist and dry. Siltstone paragravel is 15 to 35 percent and siltstone paracobbles is 5 to 20 percent. It is very strongly acid or strongly acid. It is loam or silt loam.

COMPETING SERIES: There are no competing series in this family. Braun soils are 20 to 40 inches deep to a paralithic contact.

GEOGRAPHIC SETTING: Scaponia soils are on mountains at elevations of 100 to 2,000 feet. Slopes range from 0 to 90 percent. The soils formed in colluvium weathered from siltstone. The climate is characterized by cool wet winters and warm moist summers. The mean annual precipitation is 60 to 80 inches. The mean January temperature is 35 to 37 degrees F, mean July temperature is 60 to 63 degrees F, and the mean annual temperature is 45 to 52 degrees F. The frost-free period is 100 to 180 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bacona, Braun, Glohm, Hembre, Klickitat, Mayger, Tolany, and Vernonia soils. Bacona and Vernonia soils have an argillic horizon and are fine-silty. Braun soils are 20 to 40 inches to weathered siltstone. Glohm soils are moderately well drained and have a fragipan. Hembre soils have an umbric epipedon 10 to 20 inches thick and are 40 to 60 inches deep to hard basalt bedrock. Klickitat soils have an umbric epipedon 10 to 20 inches thick and contain more than 35 percent hard rock fragments in their sola. Mayger soils are somewhat poorly drained and fine textured. Tolany soils are medial and frigid.

DRAINAGE AND PERMEABILITY: Well drained; rapid runoff; moderate permeability.

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

DISTRIBUTION AND EXTENT: Mountainous uplands of the Coast Range; northwestern Oregon; MLRA 1. This series is moderately extensive.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon

SERIES ESTABLISHED: Columbia County, Oregon, 1983.

REMARKS: Diagnostic horizons and other features
Ochric epipedon
Humic subgroup - color requirement is met from 2 to 9 inches
Cambic horizon - from 9 to 34 inches

National Cooperative Soil Survey
U.S.A.