LOCATION FERNWOOD OR
Established Series
Rev. KLS/GLG/RWL
01/2025
FERNWOOD SERIES
Landscape--western Cascade Mountains
Landform--mountain slopes, ice-scoured structural benches
Slope--2 to 90 percent
Parent material--colluvium derived from basalt and andesite mixed with volcanic ash
Mean annual precipitation--about 1800 mm
Mean annual air temperature--about 6 degrees C
Depth class--moderately deep to lithic bedrock
Drainage class--well drained
Soil moisture regime--udic
Soil temperature regime--frigid
Soil moisture subclass--typic
TAXONOMIC CLASS: Loamy-skeletal, isotic, frigid Andic Humudepts
TYPICAL PEDON: Fernwood very gravelly loam, forested
Oi--0 to 3 cm; slightly decomposed needles, leaves, and twigs
A1--3 to 13 cm; very gravelly loam, dark brown (10YR 3/3) dry, black (10YR 2/1) moist; moderate fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; weakly smeary; many very fine, fine and coarse roots; many irregular pores; 35 percent gravel and 15 percent cobbles; strongly acid (pH 5.4); clear smooth boundary
A2--13 to 28 cm; very gravelly loam, brown (10YR 4/3) dry, very dark grayish brown (10YR 3/2) moist; moderate fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; weakly smeary; many very fine, fine and coarse roots; many very fine tubular pores; 30 percent gravel and 10 percent cobbles; strongly acid (pH 5.2); clear wavy boundary
Bw1--28 to 46 cm; very cobbly loam, brown (10YR 5/3) dry, brown (10YR 4/3) moist; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; weakly smeary; common very fine and fine and few medium roots; many very fine tubular pores; 40 percent cobbles and 10 percent gravel; strongly acid (pH 5.2); gradual wavy boundary
Bw2--46 to 66 cm; extremely cobbly loam, pale brown (10YR 6/3) dry, brown (10YR 4/3) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; weakly smeary; few fine and medium roots; many very fine tubular pores; 50 percent cobbles and 10 percent gravel; strongly acid (pH 5.2); clear wavy boundary
R--66 cm; fractured andesite
TYPE LOCATION: Clackamas County, Oregon; about 6 miles west of Table Rock; in the northwest quarter of the northeast quarter of the northeast quarter of section 9, T. 7 S., R. 3 E., Willamette Meridian; Gawley Creek, Oregon, USGS 7.5-minute quadrangle; latitude 44.981 degrees, longitude -122.442 degrees, datum WGS 84 (coordinates estimated from PLSS)
RANGE IN CHARACTERISTICS:
Dry days--fewer than 45 consecutive days following summer solstice
Mean annual soil temperature--6 to 8 degrees C
Depth to lithic contact--50 to 100 cm
Thickness of umbric epipedon--18 to 50 cm
Hue--10YR, 7.5YR, or 5YR
Reaction--pH 5.1 to 6.0
Properties of layers meeting andic subgroup criteria
*Ammonium oxalate Al plus 1/2 Fe--1 to 2 percent
*Particles 0.02 to 2.0 mm diameter--greater than 30 percent of the fine-earth fraction
*Volcanic glass content in 0.02 to 2.0 mm fraction--5 to 20 percent
*1/3-bar bulk density--0.70 to 1.0 g/cm3
*Phosphate retention--50 to 100 percent
*1N KCl extractable Al--less than 2.0 cmol/kg of fine-earth material
A horizons
*Value--2 to 3 moist, 3 to 5 dry
*Chroma--1 to 3 moist or dry
*Fine-earth texture--loam or silt loam
*Clay content--15 to 22 percent
*Total fragment content--35 to 60 percent
*Gravel content--15 to 35 percent
*Cobble content--5 to 25 percent
*Combined thickness--18 to 50 cm
Bw horizons
*Value--3 or 4 moist, 4 or 5 dry
*Chroma--2 to 4 moist or dry
*Fine-earth texture--loam, silt loam, clay loam
*Clay content--18 to 30 percent
*Total fragment content--35 to 70 percent
*Gravel content--10 to 25 percent
*Cobble content--25 to 50 percent
*Combined thickness--25 to 65 cm
COMPETING SERIES:
Cadenza--depth to bedrock is greater than 150 cm
Zygore--depth to bedrock is greater than 150 cm
Dougan--averages 10 to 20 percent parafragments in the particle-size control section
GEOGRAPHIC SETTING:
Elevation--540 to 1350 m
Climate--cool, wet winters; warm, dry summers
Mean annual precipitation--1400 to 2700 mm
Mean annual air temperature--5 to 7 degrees C
Frost-free period--45 to 150 days
GEOGRAPHICALLY ASSOCIATED SOILS:
Wilhoit--less than 35 percent rock fragments in the particle-size control section; located on mountains
Zygore--depth to bedrock is greater than 150 cm; located on mountain slopes, broad ridgetops, and glacial-valley walls
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--well drained
Saturation in normal years--none
Flooding--none
Ponding--none
Saturated hydraulic conductivity (Ksat)--high or moderately high
USE AND VEGETATION:
Use--timber production, water supply, wildlife habitat, recreation
Potential natural vegetation--Douglas-fir, western hemlock, vine maple, Cascade barberry, salal, red huckleberry, western swordfern and western brackenfern
DISTRIBUTION AND EXTENT: western Cascade mountains, Oregon; MLRA 3; moderate extent
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Clackamas County, Oregon; 1982
REMARKS:
Diagnostic horizons and features recognized in this pedon
*Particle-size control section--zone from 28 to 66 cm
*Umbric epipedon--zone from 3 to 28 cm
*Cambic horizon--zone from 28 to 66 cm
*Andic subgroup feature--zone from 3 to 66 cm
*Volcanic glass--zone from 3 to 66 cm
National Cooperative Soil Survey
U.S.A.