LOCATION WHOBREY OREstablished Series
TAXONOMIC CLASS: Fine-silty over clayey, isotic over smectitic, mesic Aquertic Eutrudepts
TYPICAL PEDON: Whobrey silt loam - forested regrowth after clearcut. (Colors are for moist soil unless otherwise noted.)
Oi--0 to 1 inch; litter of slightly decomposed fern leaves, twigs, needles, and grass; abrupt smooth boundary.
A1--1 to 3 inches; dark brown (10YR 3/3) silt loam, light brownish gray (10YR 6/2) dry; moderate medium granular structure; slightly hard, very friable, slightly sticky and slightly plastic; many very fine to medium roots; many very fine to medium tubular and irregular pores; moderately acid (pH 5.8); clear wavy boundary. (1 to 5 inches thick)
A2--3 to 12 inches; brown (10YR 4/3) silt loam, pale brown (10YR 6/3) dry; weak fine and medium subangular blocky structure; hard, friable, slightly sticky and slightly plastic; many very fine to medium roots; common very fine and fine tubular and irregular pores; moderately acid (pH 5.6); gradual wavy boundary. (5 to 11 inches thick)
Bw--12 to 21 inches; dark yellowish brown (10YR 4/4) silt loam, pale brown (10YR 6/3) dry; moderate medium and coarse subangular blocky structure; hard, friable, slightly sticky and slightly plastic; common very fine to medium roots; common very fine and fine tubular and irregular pores; moderately acid (pH 5.6); clear wavy boundary. (7 to 14 inches thick)
2Bss1--21 to 27 inches; very dark gray (5Y 3/1) clay, gray (5Y 5/1) dry; moderate coarse and very coarse angular blocky structure; extremely hard, very firm, very sticky and very plastic; slickensides; few very fine and fine flattened roots; few very fine irregular pores; few fine distinct (10YR 4/6 and 7.5YR 5/4) masses of iron accumulation; about 1 percent coarse fragments, mostly rounded gravel; neutral (pH 6.8); gradual wavy boundary. (4 to 10 inches thick)
2Bss2--27 to 61 inches; very dark gray (5Y 3/1) clay, gray (5Y 5/1) dry; massive; extremely hard, very firm, very sticky and very plastic; slickensides; few very fine flattened roots; few very fine irregular pores; many rounded 2 to 5 percent gravel; moderately alkaline (pH 8.2)
TYPE LOCATION: Coos County, Oregon; approximately 3 miles east of Broadbent, Oregon; in a road cut on the south side of BLM road, south of a landing; about 500 feet north and 2,640 feet east of the southwest corner of sec. 35, T. 29 S., R. 12 W.
RANGE IN CHARACTERISTICS: The soil is usually moist but is dry in the moisture control section for a short period of less than 45 consecutive days following the summer solstice. Base saturation is presumed to exceed 60 percent between depths of 25 and 75 centimeters. The mean annual soil temperature is 47 to 54 degrees F. Thickness of the solum and depth to the clay 2Bss horizon is 20 to 36 inches.
The A horizon has hue of 7.5YR through 2.5Y, value of 3 or 4 moist, 5 or 6 dry, and chroma of 2 through 4 moist and dry.
The Bw horizon has value of 4 or 5 moist, 5 through 7 dry, and chroma of 3 or 4. Redox concentrations and depletions range from none to many, fine to medium, and faint to prominent. It is silt loam or silty clay loam and is 20 to 30 percent clay.
The 2Bss horizon has hue of 5Y or 2.5Y, value of 2 or 3 moist, 4 or 5 dry, and chroma commonly of 1, but ranging from 0 through 2. There are few to common slickensides. This horizon is clay or silty clay and averages 0 to 15 percent gravel and commonly 60 percent or more clay, but ranges from 50 to 65 percent.
COMPETING SERIES: There are no competing series.
GEOGRAPHIC SETTING: Whobrey soils are in concave to convex positions on mountain ridgetops, saddles and side slopes at elevations of 100 to 2,500 feet. Slopes are unstable and range from about 7 to 60 percent. Slumping is common. The soils formed in silty colluvium and residuum weathered from highly fractured, intensely sheared and deeply weathered sedimentary rocks of Jurassic Age (mostly the Otter Point formation). The climate is characterized by warm, wet winters and hot, moist summers. The mean annual temperature is 45 to 54 degrees F. The mean annual precipitation is typically 60 to 100 inches. In the interior mountains of Curry County, Oregon, the mean annual precipitation may range to 130 inches. The frost-free period is 120 to 220 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bohannon, Digger, Etelka, Preacher, and Remote series. All of these soils lack contrasting textures within the particle-size control section. Bohannon and Preacher soils have an umbric epipedon. Also, the Bahannon soils are 20 to 40 inches deep to bedrock. Digger soils are loamy-skeletal and are 20 to 40 inches deep to a paralithic contact. Etelka soils are fine-textured. Remote soils are loamy-skeletal.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; very slow permeability. A perched water table is as high as a depth of 1.5 to 2.5 feet from the surface at some time between December and March.
USE AND VEGETATION: These soils are used for timber production, pasture, wildlife, water supply purposes, recreation, and occasionally rural housing. The native vegetation is Douglas fir, grand fir, western hemlock, western redcedar, Port Orford cedar, red alder, Oregon white oak, salal, Pacific rhododendron, red and evergreen huckleberries, ocean spray, wild iris, western swordfern, and poison oak.
DISTRIBUTION AND EXTENT: Mountains and hills of southwestern Oregon, principally in the Klamath Mountains; MLRA 1. The series is moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES ESTABLISHED: Coos County, Oregon 1983.
REMARKS: This draft reflects a change in classification from Vertic Eutrochrepts to Aquertic Eutrudepts based on revisions to Soil Taxonomy.
Diagnostic horizons and features recognized in this pedon:
Ochric epipedon
Cambic horizon - from 11 to 20 inches (Bw horizon)