LOCATION IDANHA OR
Tentative Series
JGM/KMS
02/2025
IDANHA SERIES
Landscape--western Cascade Mountains
Landform--mountain slopes, mountaintops
Slope--0 to 90 percent
Parent material--colluvium derived from volcanic rocks mixed with volcanic ash
Mean annual precipitation--about 2600 mm
Mean annual air temperature--about 6 degrees C
Depth class--very deep
Drainage class--well drained
Soil moisture regime--udic
Soil temperature regime--cryic
Soil moisture subclass--typic
TAXONOMIC CLASS: Medial-skeletal, amorphic Typic Haplocryands
TYPICAL PEDON: Idanha gravelly medial silt loam on a 23-percent, forested slope at an elevation of 1018 m
Oi--0 to 1 cm; slightly decomposed plant material; abrupt smooth boundary
Oe--1 to 3 cm; moderately decomposed plant material; clear smooth boundary
A--3 to 22 cm; gravelly medial silt loam, brown (7.5YR 5/2) dry, very dark brown (7.5YR 2.5/2) moist; moderate fine granular structure; soft, very friable, nonsticky and nonplastic; many very fine to very coarse roots; many fine tubular pores and common medium irregular pores; 20 percent gravel; strongly acid (pH 5.1); clear smooth boundary
AB--22 to 48 cm; very gravelly medial silt loam, brown (7.5YR 5/3) dry, dark brown (7.5YR 3/3) moist; weak very fine granular structure; soft, very friable, slightly sticky, slightly plastic ; many very fine to medium and common coarse and very coarse roots; many fine tubular pores and many medium irregular pores; 50 percent gravel; strongly acid (pH 5.2); gradual smooth boundary
Bw1--48 to 83 cm; extremely gravelly medial silt loam, grayish brown (10YR 5/2) dry, dark grayish brown (10YR 4/2) moist; weak very fine subangular blocky structure; soft, very friable, slightly sticky, slightly plastic ; many very fine and fine and common medium to very coarse roots; common fine tubular pores and many medium irregular pores; 60 percent gravel, 3 percent cobbles, and 2 percent stones; strongly acid (pH 5.4); gradual wavy boundary
Bw2--83 to 150 cm; very gravelly medial loam, grayish brown (10YR 5/2) dry, brown (10YR 4/3) moist; weak very fine subangular blocky structure; soft, very friable, slightly sticky, slightly plastic; common very fine to coarse roots; common fine tubular pores and many medium irregular pores; 50 percent gravel and 5 percent cobbles; moderately acid (pH 5.6)
TYPE LOCATION: Linn County, Oregon, 4.2 km south of Idanha; 475 m south and 340 m west of the northeast corner of section 32, T. 10 S., R. 6 E.; latitude 44.6653056, longitude -122.0952778, datum WGS 84 (coordinates determined with a GPS)
RANGE IN CHARACTERISTICS:
Mean annual soil temperature--4 to 6 degrees C
Thickness of umbric epipedon--25 to 50 cm
Fine-earth texture--medial silt loam, medial loam
Sand content--20 to 45 percent
Reaction--pH 5.1 to 6.0
Estimated properties of layers with andic soil properties
*Ammonium oxalate extractable Al plus 1/2 Fe--2 to 4 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 30 percent
*Phosphate retention--85 to 100 percent
*15-bar water retention--30 to 70 percent (undried samples), greater than 15 percent (dried samples)
*1/3-bar bulk density--0.60 to 0.90 g/cm3
Particle-size control section (weighted average)
*Clay content--18 to 27 percent
*Total fragment content--35 to 75 percent
O horizons
*Composition--slightly to moderately decomposed plant material
*Thickness--0 to 10 cm
A horizon
*Hue--7.5YR, 10YR
*Value--2 to 3 moist, 3 to 5 dry
*Chroma--2 or 3 moist or dry
*Clay content--15 to 22 percent
*Total fragment content--15 to 50 percent
*Gravel content--15 to 50 percent
*Cobble content--0 to 15 percent
*Stone content--0 to 5 percent
*Thickness--20 to 36 cm
AB horizon
*Hue--7.5YR, 10YR
*Value--2 or 3 moist, 3 to 5 dry
*Chroma--2 or 3 moist or dry
*Clay content--18 to 27 percent
*Total fragment content--35 to 60 percent
*Gravel content--20 to 60 percent
*Cobble content--0 to 20 percent
*Stone content--0 to 5 percent
*Thickness--0 to 30 cm
Bw horizons
*Hue--7.5YR, 10YR
*Value--3 to 5 moist, 5 to 7 dry
*Chroma--3 or 4 moist, 3 to 6 dry
*Clay content--18 to 27 percent
*Total fragment content--35 to 70 percent
*Gravel content--20 to 60 percent
*Cobble content--0 to 30 percent
*Stone content--0 to 5 percent
COMPETING SERIES:
Battleax--averages 10 to 18 percent clay in the particle size control section
Divers--ochric epipedon
Holderman--ochric epipedon
Oatman--ochric epipedon
Ohana--ochric epipedon
Otwin--ochric epipedon
Highcamp--depth to lithic contact is 100 to 150 cm
Hummington--depth to lithic contact is 50 to 100 cm
Icecap--depth to lithic contact is 50 to 100 cm
GEOGRAPHIC SETTING:
Elevation--980 to 1525 m
Climate--cold, wet winters; mild, dry summers
Mean annual precipitation--2000 to 3600 mm
Mean annual air temperature--4 to 7 degrees C
Frost-free period--60 to 105 days
GEOGRAPHICALLY ASSOCIATED SOILS:
Blowout--aquic conditions within 50 to 100 cm of the mineral soil surface; located on complex landslides
Icecap--50 to 100 cm deep to lithic contact; located in convex positions on mountain slopes and mountaintops
Longbow--averages less than 35 percent rock fragments in the particle-size control section; located on complex landslides and mountaintops
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--well drained
Flooding--none
Ponding--none
Saturated hydraulic conductivity (Ksat)--high
USE AND VEGETATION:
Use--timber production, water supply, wildlife habitat, recreation
Potential natural vegetation--Pacific silver fir, Douglas-fir, western hemlock, Pacific rhododendron, Alaska blueberry, Cascade barberry, bunchberry dogwood, twinflower, common beargrass, bride's bonnet; commonly supports a Pacific silver fir/rhododendron-Alaska huckleberry/bunchberry dogwood (CFS654) plant association (Field Guide to the Forested Plant Associations of the Westside Central Cascades of Northwest Oregon)
DISTRIBUTION AND EXTENT: Central western Cascade Mountains, Oregon; MLRA 3; small extent
SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Bozeman, Montana
SERIES PROPOSED: Willamette National Forest, Linn County, Oregon; name from town of Idanha
REMARKS:
Diagnostic horizons and features in this pedon
*Particle-size control section--zone from 3 to 102 cm
*Umbric epipedon--zone from 3 to 48 cm
*Cambic horizon--zone from 48 to 150 cm
*Andic soil properties--zone from 3 to 150 cm
*Volcanic glass--zone from 3 to 150 cm
8/2023--all mineral layers meet criteria 2 (no ash required) and 3 for andic soil properties in the 13th edition of Keys to Soil Taxonomy.
ADDITIONAL DATA: Type location user site ID--2014OR043630
National Cooperative Soil Survey
U.S.A.