LOCATION ROCKDIRT OR
Tentative Series
JGM/KMS
06/2017
ROCKDIRT SERIES
Landscape--western Cascade Mountains
Landform--structural benches
Slope--10 to 30 percent
Parent material--colluvium derived from hard extrusive igneous rock mixed with volcanic ash throughout
Mean annual precipitation--about 2600 mm
Mean annual air temperature--about 6 degrees C
Depth class--shallow to lithic bedrock
Drainage class--well drained
Soil moisture regime--udic
Soil temperature regime--cryic
Soil moisture subclass--typic
TAXONOMIC CLASS: Medial-skeletal, amorphic Lithic Vitricryands
TYPICAL PEDON: Rockdirt stony medial loam on a south-facing, 10-percent slope of a forested mountaintop at an elevation of 1364 m (The soil was dry throughout when observed on October 3, 2012.)
Oi--0 to 3 cm; slightly decomposed plant material; abrupt smooth boundary
A--3 to 23 cm; stony medial loam, brown (7.5YR 4/2) dry, dark brown (7.5YR 3/2) moist; moderate fine granular structure; soft, friable, nonsticky and nonplastic; common very fine, fine, medium, and coarse roots; 10 percent gravel, 10 percent cobbles, and 10 percent stones; clear smooth boundary
AC--23 to 30 cm; very stony medial sandy loam, brown (7.5YR 5/3) dry, dark brown (7.5YR 3/3) moist; weak fine subangular blocky structure; soft, friable, nonsticky and nonplastic; common very fine, fine, medium, and coarse roots; 15 percent gravel, 10 percent cobbles, and 15 percent stones; abrupt wavy boundary
C--30 to 41 cm; extremely stony medial sandy loam, brown (7.5YR 5/4) dry, brown (7.5YR 4/4) moist; massive; loose, friable, nonsticky and nonplastic; common medium and coarse roots; 20 percent gravel, 20 percent cobbles, and 30 percent stones; abrupt wavy boundary
2R--41 cm; fractured andesite
TYPE LOCATION: Lane County, Oregon, about 7.4 km north of the town of Blue River; 425 m south and 245 m west of the northeast corner of section 32, T. 15 S., R. 4 E., Willamette Meridian; latitude 44.220799, longitude -122.347245, datum WGS 84 (coordinates determined with a GPS)
RANGE IN CHARACTERISTICS:
Dry days--30 to 45 consecutive days following summer solstice
Mean annual soil temperature--4 to 7 degrees C
Depth to lithic contact--25 to 50 cm below mineral soil surface
Reaction--5.1 to 6.0 throughout all mineral horizons
Thickness of andic soil properties--25 to 50 cm (below mineral soil surface)
Estimated properties of layers with andic soil properties
*1/3-bar bulk density--0.65 to 0.9 g/cm3
*Phosphate retention--greater than 85 percent
*Ammonium oxalate extractable Al + 1/2 Fe--2 to 4 percent
*15 bar water retention--less than 30 percent (undried samples), 12 to 15 percent (dried samples)
*0.02- to 2.0-mm fraction--greater than 30 percent
*Volcanic glass content in 0.02- to 2.0-mm fraction--5 to 30 percent
Particle-size control section
*Clay content--8 to 18 percent
*Total fragment content--35 to 75 percent
Oi horizon
*Thickness--3 to 8 cm
A horizon
*Hue--7.5YR, 10YR
*Value--2 to 4 moist, 4 to 6 dry
*Chroma--2 or 3 moist or dry
*Fine-earth texture--medial loam
*Clay content--10 to 18 percent
*Sand content--40 to 50 percent
*Total fragment content--15 to 35 percent
*Gravel content--5 to 15 percent
*Cobble content--5 to 15 percent
*Stone content--5 to 10 percent
*Thickness--0 to 20 cm
AC and C horizons
*Hue--7.5YR, 10YR, 2.5Y
*Value--3 to 5 moist, 4 to 7 dry
*Chroma--2 to 4 moist or dry
*Fine-earth texture--medial loam, medial sandy loam
*Clay content--8 to 18 percent
*Sand content--40 to 70 percent
*Total fragment content--35 to 75 percent
*Gravel content--10 to 30 percent
*Cobble content--10 to 30 percent
*Stone content--10 to 35 percent
*Thickness--5 to 30 cm
COMPETING SERIES:
Coerock--silt loam textures; no sandy loam textures; less than 21 percent sand in surface layer; less than 45 percent sand in subsurface layer
GEOGRAPHIC SETTING:
Elevation--1200 to 1500 m
Climate--cold, wet winters; cool, moist summers
Mean annual precipitation--2300 to 2900 mm
Mean annual air temperature--5.5 to 7.5 degrees C
Frost-free period--75 to 105 days
GEOGRAPHICALLY ASSOCIATED SOILS:
Holderman--moderately deep to lithic bedrock; on shoulders of mountaintops and in convex positions of mountain slopes
Kinzel--very deep; on glacially influenced structural benches and north-facing mountain slopes
Longbow--very deep; not skeletal; on glacially influenced structural benches
Marten--moderately deep; spodic horizon; on similar landforms with a cooler climate
DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--well drained
Saturation in normal years--none within profile
Flooding--none
Ponding--none
Saturated hydraulic conductivity (Ksat)--very high
USE AND VEGETATION:
Use--wildlife habitat, watershed, recreation
Potential natural vegetation--Pacific silver fir, Douglas-fir, western hemlock, Pacific rhododendron, dwarf Oregon grape, Alaska huckleberry, salal, beargrass
DISTRIBUTION AND EXTENT: Western Cascade Mountains, Oregon; MLRA 3; small extent
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES PROPOSED: Willamette National Forest, Lane County, Oregon; 2016; coined name
REMARKS:
Diagnostic horizons and other features in this pedon
*Particle-size control section--zone from 3 to 41 cm
*Umbric epipedon--zone from 3 to 30 cm
*Andic soil properties--zone from 3 to 41 cm
*Volcanic glass--zone from 3 to 41 cm
*Depth to lithic contact--41 cm
06/2016--Assumed to meet criteria 2 (no ash required) for andic soil properties, in the 12th edition of Keys to Soil Taxonomy. It is also assumed that enough ash is present for the soils to meet criteria 3. Additional lab data is needed to confirm the degree of ash influence.
Reaction data was not collected with this observation. Further investigation is needed.
ADDITIONAL DATA: Type location user site ID--2012OR039128
National Cooperative Soil Survey
U.S.A.