LOCATION GRINDBROOK              OR

Established Series
Rev. JAS/MHF/RWL
06/2011

GRINDBROOK SERIES

The Grindbrook series consists of very deep, moderately well drained soils formed in mixed alluvium on terraces. Slopes are 0 to 30 percent. The mean annual precipitation is about 85 inches, and the mean annual temperature is about 51 degrees F.

TAXONOMIC CLASS: Fine-silty, isotic, isomesic Oxyaquic Humudepts

TYPICAL PEDON: Grindbrook silt loam, restocked clear cut. (Colors are for moist soil unless otherwise noted.)

Oi--0 to 1 inch; slightly decomposed litter of roots, moss, leaves and twigs.

A1--1 to 11 inches; black (10YR 2/1) silt loam, dark brown (10YR 3/3) dry; moderate fine granular and moderate fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many fine and very fine roots; many very fine irregular pores; extremely acid (pH 4.0); clear wavy boundary.

A2--11 to 16 inches; very dark brown (10YR 2/2) silt loam, brown (10YR 4/3) dry; moderate fine subangular blocky structure; slightly hard, friable, moderately sticky and slightly plastic; many fine and very fine roots; many very fine tubular pores; extremely acid (pH 4.2); clear wavy boundary. (combined A horizon is 12 to 30 inches thick)

BA--16 to 29 inches; dark brown (10YR 3/3) silt loam, brown (10YR 5/3) dry; moderate fine subangular blocky structure; hard, firm, moderately sticky and moderately plastic; common very fine roots; many very fine tubular pores; very strongly acid (pH 4.6); clear smooth boundary. (0 to 15 inches thick)

Bw1--29 to 36 inches; brown (10YR 4/3) silty clay loam, yellowish brown (10YR 5/4) dry; moderate fine and medium subangular blocky structure; very hard, firm, moderately sticky and moderately plastic; few very fine roots; many very fine tubular pores; many medium distinct yellowish brown (10YR 5/4 and 5/6) masses of iron accumulation; extremely acid (pH 4.4); clear smooth boundary. (6 to 20 inches thick)

Bw2--36 to 60 inches; gray (10YR 6/1) silty clay loam, pale brown (10YR 6/3) dry; strong fine subangular blocky structure; very hard, firm, moderately sticky and moderately plastic; few very fine roots; many very fine tubular pores; many prominent yellowish brown (10YR 5/6) masses of iron accumulation; extremely acid (pH 4.4).

TYPE LOCATION: Clatsop County, Oregon; about 300 feet NW of road in the NE1/4NE1/4SW1/4 section 20, T. 7 N., R. 9 W.

RANGE IN CHARACTERISTICS: The soil is usually moist and is dry between 4 and 12 inches less than 45 consecutive days following the summer solstice. The mean annual soil temperature is 49 to 54 degrees F. The difference between mean summer and mean winter soil temperature is 5 to 9 degrees F. The umbric epipedon is 20 to 30 inches thick. The particle-size control section has less than 15 percent coarser than very fine sand and 25 to 35 percent clay. Depth to bedrock is 40 to more than 60 inches. Depth to redox depletions with chroma of 2 or less is 30 to 40 inches.

The A horizon has value of 2 or 3 moist, 2 to 5 dry, and chroma of 1 to 3 moist and dry. It is silt loam with 20 to 27 percent clay.

The Bw1 horizon has value of 2 to 4 moist, 3 to 5 dry, and chroma of 2 to 4 moist and dry. It is silt loam or silty clay loam with 20 to 35 percent clay.

The Bw2 and BC, when present, horizon has value of 4 to 6 moist and dry and chroma of 1 to 4 moist and dry. It is silty clay loam, silty clay or clay with 30 to 45 percent clay.

COMPETING SERIES: These are the Walluski and the similar Chitwood and Gleneden series. Chitwood and Gleneden soils are fine-textured and somewhat poorly drained. Walluski soils have an umbric epipedon 10 to 20 inches thick.

GEOGRAPHIC SETTING: Grindbrook soils are on old river terraces at elevations of 100 to 500 feet. Slopes range from 0 to 30 percent. The soils formed in mixed alluvium. Climate is cool and wet in the winter and cool and moist in the summer with fog. A strong marine influence limits the diurnal and annual range of temperature. Mean annual precipitation is 70 to 100 inches. The mean annual temperature is 48 to 53 degrees F. The frost-free period is 160 to 300 days. The Grindbrook soil is on the Pioneer geomorphic surface.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Ecola, Hebo and Templeton soils. Ecola soils are 20 to 40 inches deep to soft bedrock. Hebo soils are poorly drained. Templeton soils have an umbric epipedon less than 20 inches thick.

DRAINAGE AND PERMEABILITY: Moderately well drained; slow permeability. A perched high water table fluctuates between depths of 2.0 to 3.0 feet below the surface from November through May.

USE AND VEGETATION: These soils are used for building sites, pasture, watershed, timber production and wildlife habitat. Native vegetation includes western hemlock, Sitka spruce, Douglas-fir, red alder, salmonberry, red huckleberry, vine maple, western swordfern and brackenfern.

DISTRIBUTION AND EXTENT: On old river terraces along the Oregon coast; MLRA 4A. The series is inextensive.

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

SERIES ESTABLISHED: Clatsop County, Oregon, 1984.

REMARKS: Diagnostic horizons and features in this pedon include:

Umbric epipedon - from 1 to 29 inches (A1, A2, and BA horizons).

Cambic horizon - from 29 to 60 inches (Bw1 and Bw2 horizons)

Depth to redox depletions with matrix chroma of 2 or less - 36 inches (Bw2 horizon).

All diagnostic horizons and features are measured from the top of the first mineral horizon.

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National Cooperative Soil Survey
U.S.A.