LOCATION LARCHMOUNT WAEstablished Series
TAXONOMIC CLASS: Medial, amorphic, frigid Typic Hapludands
TYPICAL PEDON: Larchmount cobbly silt loam, open woodland. (Colors for moist soil unless otherwise stated)
A--0 to 23 inches; black (10YR 2/1) cobbly silt loam, very dark gray (10YR 3/1) when dry; strong medium and coarse granular structure; slightly hard, firm, nonsticky, nonplastic with smeary feel; abundant fine and medium roots; moderately acid; gradual wavy boundary. (18 to 24 inches thick)
Bw--23 to 34 inches; dark grayish brown (10YR 4/2) cobbly heavy silt loam, light brownish gray (10YR 6/2) when dry; weak fine subangular blocky structure; hard, firm, slightly sticky, plastic; plentiful fine and medium roots; many fine pores; slightly acid; clear smooth boundary. (8 to 14 inches thick)
BC--34 to 48 inches; dark grayish brown (2.5Y 4/2) cobbly heavy silt loam, light brownish gray (2.5Y 6/2) when dry; massive, hard, friable, slightly sticky, plastic; few fine roots; many medium and fine tubular pores; moderately acid; clear wavy boundary. (10 to 20 inches thick)
2C--48 to 62 inches; olive gray (5Y 5/2) very stony loam, light gray (5Y 7/2) when dry; massive; hard, friable, sticky, plastic; no roots; very strongly acid; irregular wavy boundary. (12 to 24 inches thick)
3R--62 inches; fractured granodiorite.
TYPE LOCATION: Clark County, Washington; about 7 miles northeast of Washougal, Washington at a point approximately 200 feet west and 200 feet south of east quarter corner of sec. 35, T.3N., R.4E., on State Forest Land.
RANGE IN CHARACTERISTICS: Mean annual soil temperature at 20 inches is 45 to 47 degrees F.
Moist color of the A horizon ranges from black to very dark brown.
The Bw horizon ranges from dark grayish brown to brown, and from silt loam to loam. Content of coarse fragments in the from 20 to 35 percent. Soil reaction ranges from slightly acid to very strongly acid.
COMPETING SERIES: These are the Domell, Lempira, Murtip, and Volash series. Domell soils have less than 18 percent apparent clay in the particle-size control section and an umbric epipedon less than 20 inches thick. Lempira soils have a solum more than 60 inches thick. Murtip soils have an umbric epipedon 10 to 20 inches thick. Volash soils have a xeric moisture regime and slightly and or neutral.
GEOGRAPHIC SETTING: These soils occur on ridge tops and mountain slopes at elevations of 1,800 to 3,000 feet. Slopes are 5 to 75 percent. The regolith consists of predominantly volcanic ash mixed with some pedons and residuum from igneous rocks. Larchmount soils occur in a humid marine climate having an annual precipitation of 90 to 100 inches with relatively cool dry summers and mild wet winters; an average January temperature of 30 degrees F.; and average July temperature of 60 degrees F., and an average annual temperature of 45 degrees F.; and an average growing season of 80 days.
GEOGRAPHICALLY ASSOCIATED SOILS: Kinney soils are the most common associates. Kinney soils have a bulk density of more than 0.85 g/cc below 14 inches.
DRAINAGE AND PERMEABILITY: Well drained. Runoff is medium to very rapid. Permeability is moderate.
USE AND VEGETATION: Used for a woodland. Native vegetation is western hemlock, Noble fir, Douglas-fir and with an understory of vine maple, huckleberry, common bear grass, Sitka mountain ash, redflower currant, salmonberry, thimbleberry, salal, western brackenfern, western swordfern, lupine, and Indian paintbrush.
DISTRIBUTION AND EXTENT: Southwestern Washington and northwestern Oregon. Series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Clark County, Washington, 1967.
REMARKS: Classification only changed 4/94 because of recent amendments to Soil Taxonomy.
Diagnostic horizons and feature recognized in this pedon are an umbric epipedon from the surface to 23 inches and a cambic horizon from 23 to 34 inches.