LOCATION HOCKINSON WAEstablished Series
TAXONOMIC CLASS: Coarse-loamy, mixed, superactive, nonacid, mesic Fluvaquentic Endoaquepts
TYPICAL PEDON: Hockinson loam, pasture. (Color for moist soil unless otherwise noted.)
Ap--0 to 6 inches; very dark gray (10YR 3/1) loam, gray (10YR 5/1) dry; few fine distinct dark reddish brown (5YR 3/4) redox concentrations, reddish brown (5YR 5/4) dry; moderate fine subangular blocky and moderate fine granular structure; slightly hard, friable, moderately sticky and slightly plastic; many fine roots; strongly acid; abrupt smooth boundary. (6 to 9 inches thick)
BAg--6 to 16 inches; dark gray (10YR 4/1) loam, gray (10YR 6/1) dry; common fine distinct reddish brown (5YR 4/3) redox concentrations, reddish brown (5YR 5/4) dry; many medium prominent yellowish red (5YR 5/8) redox concentrations, yellowish red (5YR 5/8) dry; moderate fine subangular blocky structure; hard, friable, slightly sticky and slightly plastic; many fine fibrous roots; many fine and medium pores; strongly acid; clear wavy boundary. (9 to 12 inches thick)
Bg1--16 to 23 inches; dark gray (10YR 4/1) loam, light brownish gray (10YR 6/2) dry; common medium prominent yellowish red (5YR 5/8) redox concentrations, reddish yellow (5YR 6/8) dry; weak coarse prismatic parting to weak medium subangular blocky structure; hard, friable, slightly sticky and slightly plastic; few fine fibrous roots; common fine and medium pores; thin clay films in pores; few black stains on surfaces of peds; moderately acid; clear boundary. (5 to 8 inches thick)
Bg2--23 to 30 inches; dark gray (10YR 4/1) fine sandy loam, light brownish gray (10YR 6/2) dry; many medium prominent yellowish red (5YR 5/8) redox concentrations, yellowish red (5YR 5/8) dry; weak coarse prismatic structure; very hard, firm, slightly sticky and slightly plastic; few fine roots on surfaces of peds; many fine and medium pores; thin clay films in pores; slightly acid; abrupt wavy boundary. (6 to 9 inches thick)
Bg3--30 to 41 inches; very dark grayish brown (10YR 3/2) loam, light brownish gray (10YR 6/2) dry; many medium prominent yellowish red (5YR 5/8) redox concentrations, yellowish red (5YR 5/8) dry; weak very coarse prismatic structure; very hard, firm, slightly sticky and slightly plastic; common fine and few medium pores; thin patchy clay films on surfaces of peds; few fine black coatings; slightly acid; abrupt wavy boundary. (8 to 12 inches thick)
Cg1--41 to 51 inches; dark grayish brown (10YR 4/2) loam, light brownish gray (10YR 6/2) dry; common fine distinct yellowish red (5YR 4/6) redox concentrations, yellowish red (5YR 5/6) dry; massive; thin lenses of silt loam, and fine sandy loam; slightly hard, friable, slightly sticky and slightly plastic; common fine and medium pores; thin clay films in pores; moderately acid; gradual wavy boundary. (8 to 12 inches thick)
Cg2--51 to 74 inches; grayish brown (2.5Y 5/2) silt loam, light olive brown (2.5Y 5/4) dry; many medium prominent yellowish red (5YR 5/8) redox concentrations, yellowish red (5YR 5/8) dry; weak coarse prismatic parting to weak medium platy structure; hard, friable, slightly sticky and moderately plastic; common medium tubular pores; thin clay films in pores; moderately acid.
TYPE LOCATION: Clark County, Washington; 100 feet east and 100 feet north of telephone pole No. 9 on NE 199th Street, 0.4 mile east of intersection with N. 142 Avenue, in SE1/4 SE1/4 sec. 2, T.3N., R.2E.
RANGE IN CHARACTERISTICS: The mean annual soil temperature is 48 to 54 degrees F. Content of coarse fragments ranges from 0 to 15 percent.
The A horizon has moist value of 2 or 3 and moist chroma of 0 through 2.
The Bg horizon has moist value of 3 through 5 and moist chroma of 0 through 2 with prominent reddish brown or yellowish red redox concentrations. It is sandy loam to silt loam and dry consistence is hard to very hard.
The Cg horizon has moist value of 4 through 6 and moist chroma of 0 through 2 with prominent redox concentrations. Texture ranges from sandy loam to silt loam.
COMPETING SERIES: These are the Briscot and Rippowen series. Briscot soils have surface colors of value moist 3 or 4 and value dry of 5 through 7. Rippowan soils have less than 8 percent clay in the particle-size control section.
GEOGRAPHIC SETTING: These soils are in depressional areas on stream terraces at elevations of 200 to 400 feet. They formed in mixed alluvium. Hockinson soils occur in humid marine climate with relatively cool dry summers and mild moist winters. Average January temperature is 37 degrees F.; average July temperature is 64 degrees F.; mean annual temperature is 51 degrees F. The mean annual precipitation is 51 inches.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Cove, Dollar and Hesson soils. Cove soils have more than 35 percent clay. Dollar soils have a fragipan. Hesson soils have an argillic horizon and have more than 35 percent clay.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained, some gently sloping areas are moderately well drained. Runoff is slow. Permeability is very slow.
USE AND VEGETATION: Woodland, small grain, hay and pasture. Native vegetation is red alder, Oregon white oak, Oregon ash, western redcedar, and grand fir, with an understory of hardhack, sedges, willow, vine maple, salmonberry, red huckleberry, salal, longtube twinflower, violet, western brackenfern, western hazel, cascara buckthorn, and rose.
DISTRIBUTION AND EXTENT: Southwestern Washington. Series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Clark County, Washington, 1971.
REMARKS: Diagnostic horizons and features recognized in this pedon are an ochric epipedon from the surface to 6 inches and a cambic horizon from 6 to 41 inches. These soils are assumed to have an irregular decrease in organic carbon and are assumed not to be subject to flooding.