LOCATION CHITWOOD OR

Established Series
Rev. GEO/JAS/RWL
11/2012

CHITWOOD SERIES

The Chitwood series consists of very deep, somewhat poorly drained soils on coastal marine and valley terraces. They formed in alluvium derived from sedimentary rocks. Slopes range from 0 to 15 percent. The mean annual temperature is about 52 degrees F. and the mean annual precipitation is about 70 inches.

TAXONOMIC CLASS: Fine, isotic, isomesic Aquandic Humudepts

TYPICAL PEDON: Chitwood medial silt loam-improved pasture, on a 2 percent slope at an elevation of 80 feet. (Colors are for moist soil unless otherwise noted.)

Ap--0 to 7 inches; very dark grayish brown (10YR 3/2) medial silt loam, grayish brown (10YR 5/2) dry; weak very fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; weakly smeary; many very fine roots; many very fine irregular pores; strongly acid (pH 5.2); clear smooth boundary.

A--7 to 11 inches; very dark grayish brown (10YR 3/2) medial silt loam, grayish brown (10YR 5/2) dry; moderate very fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; weakly smeary; many very fine roots; many very fine and fine irregular pores; very strongly acid (pH 5.0); clear smooth boundary. (Combined thickness of the A horizon is 7 to 20 inches thick)

BA--11 to 19 inches; dark brown (10YR 3/3) silty clay loam, brown (10YR 5/3) dry; moderate medium subangular blocky structure parting to moderate very fine angular blocky; moderately hard, firm, moderately sticky and moderately plastic; common fine roots; many very fine tubular pores; few fine faint continuous very dark grayish brown (10YR 3/2) organic stains on faces of peds; few fine faint dark yellowish brown (10YR 4/4) and distinct yellowish brown (10YR 5/6) iron masses, irregular in the matrix; very strongly acid (pH 5.0); clear smooth boundary. (0 to 11 inches thick)

Bw--19 to 29 inches; dark yellowish brown (10YR 3/4) silty clay, yellowish brown (10YR 5/4) dry; moderate medium subangular blocky structure parting to weak very fine angular blocky; moderately hard, firm, moderately sticky and moderately plastic; few fine roots; few fine and common very fine tubular pores; few distinct continuous very dark grayish brown (10YR 3/2) organic stains on faces of peds and on surfaces along pores; many medium distinct strong brown (7.5YR 5/6) iron masses, irregular in the matrix, and common medium distinct grayish brown (10YR 5/2) iron depletions, irregular in the matrix; very strongly acid (pH 5.0); clear smooth boundary. (10 to 40 inches thick)

BC--29 to 60 inches; dark yellowish brown (10YR 3/4) silty clay loam, yellowish brown (10YR 5/4) dry; weak subangular blocky structure; moderately hard, firm, moderately sticky and moderately plastic; few fine roots; common very fine tubular pores; common distinct continuous very dark grayish brown (10YR 3/2) organic stains on faces of peds and on surfaces along pores; common coarse and medium prominent strong brown (7.5YR 5/8) and yellowish red (5YR 5/6) iron masses, irregular in the matrix and common coarse and medium distinct grayish brown (10YR 5/2) iron depletions, irregular in the matrix; common thin organic stains; very strongly acid (pH 4.6).

TYPE LOCATION: Tillamook County, Oregon; about 1,500 feet south and 1,000 feet east of the northwest corner of section 10, T.2S., R.9W.; USGS Tillamook topographic quadrangle; latitude 45 degrees 24 minutes 55 seconds N. and longitude 123 degrees 46 minutes 31 seconds W.; NAD 27.

RANGE IN CHARACTERISTICS: The soil is usually moist, is saturated with water extended periods during the winter, and is dry for less than 45 consecutive days between the depths of about 4 to 12 inches after the summer solstice. Redox depletions with moist chroma of 2 or less are at a depth of 18 to 24 inches and represent less than 50 percent of the matrix. The mean annual soil temperature is 50 to 54 degrees F. The difference between mean summer and mean winter soil temperature varies from 5 to 9 degrees F under canopy cover. The umbric epipedon is 10 to 20 inches thick. The upper 6 to 10 inches has an estimated Alox + Feox of 2.0 to 3.0 percent and a moist bulk density of 0.80 to 0.90 g/cc. The lower part to a depth of 20 inches, has Alox + Feox of 1.0 to 3.0 percent and a moist bulk density of 0.90 to 1.0 g/cc. Andic soil properties, when present, do not extend below a depth of 14 inches. A substratum containing paragravel, paracobbles, and parastones is below a depth of 40 inches in some pedons.

The Ap or A horizon has hue of 10YR, value of 2 or 3 moist, 3 to 5 dry, and chroma of 2 or 3 moist and dry. Texture is dominantly medial silt loam in the upper part and medial silt loam or silt loam in the lower part with 20 to 27 percent clay by field estimate. A few areas are silty clay loam with 27 to 35 percent clay. It is extremely acid to moderately acid.

The BA horizon, when present, has hue of 10YR, value of 3 moist, 3 through 5 dry, and chroma of 3 moist and dry. Texture is silty clay loam with 30 to 37 percent clay. It is extremely acid to strongly acid

The Bw horizon has value of 3 through 6 moist, 4 through 7 dry and chroma of 2 through 4 moist and dry. Texture is silty clay or silty clay loam with 35 to 45 percent clay. It is extremely acid to strongly acid.

The BC or C horizon, when present, has hue of 10YR or 2.5Y, value of 3 through 6 moist, 4 through 7 dry, and chroma of 1 through 4 moist and 2 through 4 dry. Texture is silty clay loam or silty clay with 35 to 45 percent clay and 0 to 10 percent paragravel.

COMPETING SERIES: This is the Wishkah series. Wishkah soils have an ochric epipedon and texture control section averaging 40 to 50 percent clay.

GEOGRAPHIC SETTING: The Chitwood soils are on coastal marine and valley terraces. Slopes are 0 to 15 percent. The soils formed in mixed old fine textured alluvial deposits from sedimentary rocks. Elevations range from 20 to 400 feet. The climate is characterized by cool wet winters and cool moist summers with fog and low clouds. The mean annual precipitation is 60 to 100 inches. The average January temperature is 43 degrees F. and the average July temperature is 61 degrees F. The mean annual temperature is 48 to 53 degrees F. The frost-free season is 160 to 300 days. These soils are on the Whiskey Run geomorphic surface.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Hebo and Knappa soils. Hebo soils have aquic conditions with redox concentrations at a depth of 10 inches or less. Knappa soils are well drained and have a texture control section that averages less than 35 percent clay. Hebo soils are on concave areas of terraces and Knappa soils are on nearly level to convex areas of terraces.

DRAINAGE AND PERMEABILITY: Somewhat poorly drained; slow permeability. An apparent high water table is at its uppermost limit from November through May.

USE AND VEGETATION: The soils are used for pasture and forage crops. Native vegetation is mainly of Douglas-fir, western hemlock, western redcedar, Sitka spruce, and red alder, rose, scattered rushes and sedges, vine maple, salmonberry, western swordfern, red elderberry, and grasses.

DISTRIBUTION AND EXTENT: Coastal valley and marine terraces of Western Oregon; MLRA 4A. The series is moderately extensive.

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

SERIES ESTABLISHED: Tillamook County, Oregon, 1961.

REMARKS: Diagnostic horizons and features in this pedon include:
Umbric epipedon - from the surface to 19 inches (Ap, A and BA horizon).
Cambic horizon - from 19 to 29 inches (Bw horizon)
Aquic feature common redox depletions beginning at a depth of 19 inches (Bw horizons).
Andic subgroup feature - from 0 to 11 inches (Ap and A horizon) qualifying for andic soil properties. Based on data from NSSL sample S02OR-007-002 and on data collected for similar soils.

A proposal was submitted to NSSC (2000) to revise the definition of medial to also include those soil properties qualifying for the Andic subgroup under criteria #1 for andic soil properties. If accepted, medial modifiers would be used for those horizons meeting the andic subgroup criteria although not meeting andic soil properties.

National Cooperative Soil Survey
U.S.A.