LOCATION TWOGIRLS                OR

Tentative Series
JGM/KMS
01/2017

TWOGIRLS SERIES

Landscape--western Cascade Mountains
Landform--mountain slopes
Slope--45 to 90 percent
Parent material--colluvium derived from welded tuff
Drainage class--well drained
Depth class--very deep
Mean annual precipitation--2100 mm
Mean annual air temperature--7 degrees C
Soil moisture regime--udic
Soil temperature regime--frigid
Soil temperature subclass--typic

TAXONOMIC CLASS: Loamy-skeletal, isotic, frigid Typic Dystrudepts

TYPICAL PEDON: Twogirls gravelly silt loam on a forested, west-facing, 48-percent slope at an elevation of 940 m

Oi--0 to 3 cm; slightly decomposed plant material; abrupt smooth boundary

A--3 to 13 cm; gravelly silt loam, pale brown (10YR 6/3) dry, brown (10YR 4/3) moist; weak fine subangular blocky structure; slightly hard, friable, nonsticky and nonplastic; common very fine, fine, and coarse and many medium roots; many very fine and common fine and medium irregular pores; 15 percent welded tuff gravel and 2 percent welded tuff cobbles; moderately acid (pH 5.6); clear wavy boundary

Bw1--13 to 32 cm; gravelly silt loam, light gray (10YR 7/2) dry, brown (10YR 5/3) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine, fine, and coarse and many medium roots; many very fine and common fine and medium irregular pores; 25 percent welded tuff gravel; moderately acid (pH 5.6); gradual wavy boundary

Bw2--32 to 86 cm; very gravelly silt loam, light gray (10YR 7/2) dry, brown (10YR 5/3) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine and fine and many medium roots; many very fine, fine, and medium irregular pores; 35 percent welded tuff gravel and 15 percent welded tuff cobbles; moderately acid (pH 5.8); gradual wavy boundary

BC--86 to 150 cm; very cobbly silt loam, very pale brown (10YR 7/3) dry, brown (10YR 5/3) moist; weak medium subangular blocky structure; slightly hard, friable, nonsticky and nonplastic; common fine and medium roots; common very fine and many fine and medium irregular pores; 25 percent welded tuff gravel, 25 percent welded tuff cobbles, and 5 percent welded tuff stones; moderately acid (pH 5.8)

TYPE LOCATION: Linn County, Oregon, about 21.5 km south of Detroit; 630 m south and 575 m east of the northwest corner of section 8, T. 12 S., R. 6 E.; latitude 44.6112778, longitude -122.2863889, 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--5 to 7 degrees C
Reaction--5.5 to 6.5

Particle-size control section
*Clay content--8 to 18 percent
*Total fragment content--35 to 70 percent

O horizon
*Thickness--1 to 8 cm

A horizon
*Value--4 or 5 moist, 5 to 7 dry
*Chroma--2 to 4 moist, 2 or 3 dry
*Fine-earth texture--silt loam
*Clay content--8 to 18 percent
*Sand content--20 to 50 percent
*Total fragment content--15 to 35 percent
*Gravel content--15 to 35 percent
*Cobble content--0 to 10 percent
*Thickness--10 to 20 cm

Bw1 horizon
*Hue--10YR, 2.5Y
*Value--4 to 6 moist, 5 to 7 dry
*Chroma--2 or 3 moist or dry
*Fine-earth texture--silt loam, loam
*Clay content--10 to 18 percent
*Sand content--20 to 50 percent
*Total fragment content--20 to 50 percent
*Gravel content--20 to 40 percent
*Cobble content--0 to 25 percent
*Stone content--0 to 5 percent
*Thickness--10 to 30 cm

Bw2 horizon
*Hue--10YR, 2.5Y
*Value--4 to 6 moist, 5 to 7 dry
*Chroma--2 or 3 moist or dry
*Fine-earth texture--silt loam, loam
*Clay content--10 to 18 percent
*Sand content--20 to 50 percent
*Total fragment content--35 to 60 percent
*Gravel content--25 to 45 percent
*Cobble content--10 to 25 percent
*Stone content--0 to 10 percent
*Thickness--40 to 100 cm

BC horizon
*Hue--10YR, 2.5Y
*Value--4 to 6 moist, 5 to 7 dry
*Chroma--2 or 3 moist or dry
*Fine-earth texture--silt loam, loam
*Clay content--8 to 18 percent
*Sand content--20 to 50 percent
*Total fragment content--45 to 75 percent
*Gravel content--20 to 50 percent
*Cobble content--15 to 40 percent
*Stone content--0 to 15 percent

COMPETING SERIES:
Eveleth--dense glacial till within 100 cm of mineral soil surface
Owlridge, Rilea--lithic contact within 100 cm of mineral soil surface
Shagawa--E horizon; lithologic discontinuity; material below lithologic discontinuity greater than 50 percent sand

GEOGRAPHIC SETTING:
Elevation--800 to 1200 m
Climate--warm, dry summers; cool, wet winters
Mean annual precipitation--1900 to 2300 mm
Mean annual air temperature--6 to 8 degrees C
Frost-free period--90 to 120 days

GEOGRAPHICALLY ASSOCIATED SOILS:
Chamate--mesic soil temperature regime; in similar landform and slope positions
Flimflam--25 to 50 cm deep to lithic contact (shallow); on shoulders of associated slopes
Owlridge--50 to 100 cm deep to lithic contact (moderately deep); on backslopes and nose slopes of associated slopes and steeper slopes

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--well drained
Saturation during normal years--none
Flooding--none
Ponding--none
Saturated hydraulic conductivity (Ksat)--moderately high or high

USE AND VEGETATION:
Use--watershed, recreation, timber production, wildlife habitat
Potential natural vegetation--western hemlock, Douglas-fir, Pacific rhododendron, beargrass, salal, dwarf Oregon grape, red huckleberry; commonly supports a western hemlock/rhododendron-beargrass (CHS357) plant association (Field Guide to the Forested Plant Associations of the Westside Central Cascades of Northwest Oregon)

DISTRIBUTION AND EXTENT: Western slopes of the central Cascade Mountains, Oregon; MLRA 3; small extent

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon

SERIES PROPOSED: Willamette National Forest, Lane County, Oregon; 2013; name from Two Girls Falls, a landform in Willamette National Forest

REMARKS:
Diagnostic horizons and other features in this pedon
*Ochric epipedon
*Particle-size control section--zone from 28 to 103 cm
*Cambic horizon--zone from 13 to 86 cm

08/2016--Some investigation is needed to determine whether the soils have an ash influence, given the levels of ash in nearby soils.

ADDITIONAL DATA: Type location user site ID--2014OR043868

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National Cooperative Soil Survey
U.S.A.