LOCATION COQUILLE OR+CA WA

Established Series
Rev. JAS/TDT/RWL
02/2011

COQUILLE SERIES

The Coquille series consists of very deep, very poorly drained soils that formed in mixed alluvium along tidal influenced flood plains. Slopes are 0 to 1 percent. The mean annual temperature is about 51 degrees F. and the mean annual precipitation is about 80 inches.

TAXONOMIC CLASS: Fine-silty, mixed, superactive, nonacid, isomesic Fluvaquentic Endoaquepts

TYPICAL PEDON: Coquille silt loam, native vegetation. (Colors are for moist soil unless otherwise noted.)

A--0 to 6 inches; very dark gray (10YR 3/1) silt loam, gray (10YR 5/1) dry; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many very fine and fine roots; many very fine irregular pores; moderately acid (pH 5.8); clear smooth boundary. (4 to 7 inches thick)

Bw--6 to 16 inches; dark grayish brown (10YR 4/2) silt loam, grayish brown (10YR 5/2) dry; weak medium subangular blocky structure; slightly hard, friable, moderately sticky and slightly plastic; common very fine roots; many very fine tubular pores; many very fine distinct dark yellowish brown (10YR 4/6) redox concentrations; moderately acid (pH 6.0); clear smooth boundary. (8 to 20 inches thick)

C2--16 to 30 inches; dark grayish brown (10YR 4/2) silt loam, light brownish gray (10YR 6/2) dry; massive; slightly hard, friable, slightly sticky and slightly plastic; common very fine roots; many very fine tubular pores; many very fine and fine, prominent strong brown (7.5YR 5/6) redox concentrations; moderately acid (pH 6.0); clear smooth boundary. (8 to 30 inches thick)

2Cg--30 to 60 inches; dark gray (5Y 4/1) silt loam, light brownish gray (2.5Y 6/2) dry; massive; slightly hard, friable, slightly sticky and slightly plastic and very fluid; common very fine roots; many very fine tubular pores; slightly acid (pH 6.4).

TYPE LOCATION: Clatsop County, Oregon; about 175 feet N.E. of boat ramp slough; SE1/4SW1/4NW1/4 section 13, T. 8 N., R. 9 W.

RANGE IN CHARACTERISTICS: The soil has a permanent high water table at or near the surface and fluctuates with the tides unless diked and drained. Extreme high tides and high tides along with peak freshwater flows inundate the soil unless protected by dikes or levees. The mean annual soil temperature is 47 to 54 degrees F. The difference between mean summer and mean winter soil temperature varies from 5 to 9 degrees F. Depth to the massive dark gray 2Cg horizon is 24 to 50 inches. The particle-size control section averages 20 to 35 percent clay and less than 15 percent coarser than very fine sand. Under natural conditions soil pH is moderately acid to neutral. When diked and drained soil pH is extremely acid to very strongly acid, but may be strongly acid to moderately acid below 40 inches.

The A horizon has hue of 2.5Y or 10YR, value of 3 or 4 moist, 5 or 6 dry and chroma of 1 or 3. It is silt loam or silty clay loam and has 20 to 30 percent clay.

The C horizon has hue of 10YR, 2.5Y or 5Y, value of 3 or 4 moist, 6 or 7 dry and chroma of 2. It is silt loam or silty clay loam and has 20 to 35 percent clay. In some pedons it has thin lenses of fibrous peat less than 4 inches thick or has thin sand layers. It has common or many distinct or prominent redox concentrations with 10YR to 5YR hue.

The 2C or 2Cg horizon has hue of 2.5Y to 5BG, value of 2.5, 3 or 4 moist, 6 or 7 dry and chroma of 1 or less moist and 2 or less dry. It consists of bay sediments stratified with medium to fine textured materials and thin fine lenses of peat and coarse textured materials. Some pedons have fine sand substratums below 40 inches. It is loam, silty clay loam, silty clay or clay with 25 to 65 percent clay.

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING: Coquille soils have formed in slightly higher areas of tide influenced flood plains along bays and streams that flow into the ocean. The soils formed in recent alluvium over massive bay sediments. Slopes are 0 to 1 percent. They are at elevations of 0 to 20 feet and are subject to tidal and freshwater overflow unless protected by dikes or levees. The climate is characterized by cool moist summers and cool wet winters. The mean annual precipitation is 60 to 120 inches. The average July temperature is about 59 degrees F. the average January temperature is about 38 degrees F. The mean annual air temperature is 45 to 54 degrees F. The frost-free season is 180 to 245 days. The soils are on the Ingram geomorphic surface.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Brallier, Brenner, Clatsop, Nehalem and Nestucca soils. Brallier soils are Histosols. Brenner, Nehalem and Nestucca soils have umbric epipedons and are on flood plains. Clatsop soils have a histic epipedon.

DRAINAGE AND PERMEABILITY: Very poorly drained; very slow runoff or ponded; slow permeability. Subject to tidal and freshwater overflow unless protected by dikes or levees.

USE AND VEGETATION: Native vegetation consists primarily of willow, salmonberry, tussocks, tufted hairgrass, Oregon gumweed, Douglas aster, saltgress, seaside plaintain and pickleweed.. Where protected by dikes or levees and drained, permanent pasture is the major use. In the unprotected area, Coquille soils are important for wetland wildlife habitat.

DISTRIBUTION AND EXTENT: Tide influenced areas of western Oregon, California and Washington; MLRA 4A and 4B. The series is not extensive.

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

SERIES ESTABLISHED: Marshfield Area, Oregon, 1909.

REMARKS: Diagnostic horizons and features recognized in this pedon:

Ochric epipedon - from the surface to 6 inches (A horizon)

Cambic horizon from 6 to 16 inches (Bw horizon)

Aquic moisture regime - chroma of 2 or less with redox concentrations at 6 inches.

Drained areas would be re-correlated to the Nuby Series. Nuby soils have similar landscape position and are in the acid family.

National Cooperative Soil Survey
U.S.A.