LOCATION TWINLAKE ORTentative Series
TAXONOMIC CLASS: Loamy-skeletal, isotic Lithic Haplocryepts
TYPICAL PEDON: Twinlake very gravelly ashy sandy loam - woodland, on a 60 percent eastfacing slope at an elevation of 6,900 feet. (Colors are for moist soil unless otherwise noted.)
A--0 to 5 inches; dark brown (10YR 3/3) very gravelly ashy sandy loam, brown (10YR 5/3) dry; weak fine and very fine subangular blocky structure; loose, very friable, nonsticky and nonplastic; common fine and few medium and coarse roots; few fine irregular pores; 30 percent gravel, 10 percent cobbles, and 5 percent stones; moderately acid (pH 6.0); clear wavy boundary. (3 to 7 inches thick)
Bw--5 to 14 inches; dark yellowish brown (10YR 3/4) extremely gravelly ashy sandy loam, yellowish brown (10YR 5/4) dry; weak fine and medium subangular blocky structure; loose, very friable, nonsticky and nonplastic; few fine, medium, and coarse roots; 40 percent gravel, 10 percent cobbles, and 10 percent stones; slightly acid (pH 6.5); abrupt wavy to irregular boundary. (6 to 17 inches thick)
R--14 inches; argillite
TYPE LOCATION: Grant County, Oregon
Section 17 (NE 1/4, SE 1/4, NW 1/4), T. 8 S., R. 36 E.
Latitude: 44 degrees, 52 minutes, 17 seconds North
Longitude: 118 degrees, 19 minutes, 36 seconds West
UTM Coordinates: zone 11; 4,969,302.5 northing, 395,201.6 easting; NAD27
USGS Quadrangle: Mount Ireland
RANGE IN CHARACTERISTICS:
Soil Temperature: cryic regime
Mean Annual Soil Temperature: 33 to 41 degrees F
Mean Summer Soil Temperature: 39 to 48 degrees F
Mean Winter Soil Temperature: 26 to 36 degrees F
Soil Moisture: udic regime; dry 30 to 45 consecutive days in summer
Particle-size Control Section: mineral soil surface to 14 inches if depth to bedrock is less than 14 inches or 10 inches below mineral soil surface to a lithic contact
Clay content, average: 2 to 10 percent
Rock fragment content, average: 50 to 85 percent
Diagnostic Horizons and Features:
vitrandic subgroup properties: throughout the solum
Al+1/2Fe(aox): 0.7 to 1.0 percent
bulk density: 1.0 to 1.3 percent (g/cc)
P retention: 60 to 70 percent
glass content in the 0.02-2.0mm fraction: 5 to 25 percent
water content 1500 kPa (air dried): 10 to 15 percent
8Si + 2Fe (aox): 1 to 2 percent
ochric epipedon:
cambic horizon: 6 to 17 inches thick
lithic contact, depth: 10 to 20 inches
Major Horizons:
A horizon:
color, moist: 10YR 2/2, 3/2, 3/3
color, dry: 10YR 3/3, 5/2, 5/3, 5/4
texture: GRV-ASHY-SL, GRV-ASHY-L
clay content: 5 to 12 percent
rock fragment content: 40 to 60 percent
gravel: 30 to 55 percent
cobbles: 0 to 10 percent
stones: 0 to 5 percent
reaction: moderately acid to slightly acid; pH: 5.6 to 6.5
Bw horizon:
color, moist: 10YR 3/4, 4/6, 5/4, 5/6
color, dry: 10YR 5/2, 5/3, 5/4, 6/4
texture: GRX-ASHY-SL, GRV-ASHY-SL, GRV-ASHY-L, GRX-ASHY-L
clay content: 2 to 10 percent
rock fragment content: 50 to 85 percent
gravel: 30 to 80 percent
cobbles: 0 to 20 percent
stones: 0 to 10 percent
reaction: strongly acid to slightly acid; 5.1 to 6.5 pH
COMPETING SERIES:
Banker (WA) - xeric moisture regime; O horizon is present; formed in residuum and colluvium from sedimentary rock fragments are channers and flags;
Caseypeak MT) - soil is mixed superactive; soil is miss-classified and should be in a shallow family and not in a lithic subgroup; ustic moisture regime; paralithic contact; O horizon is present; no influence of volcanic ash
Cobblank (AK) - soil is mixed superactive; O horizon is present; formed in a thin mantle of silty loess; no influence of volcanic ash; subarctic climate
Cowood (MT) - soil is mixed superactive; O horizon is present; no influence of volcanic ash
Hechtman (WY) - soil is mixed superactive; O horizon is present; no influence of volcanic ash
Hotter (CO) - soil is mixed superactive; formed in slope alluvium or residuum from sandstone and shale; no influence of volcanic ash; 10 to 18 percent clay in particle-size control section
Jarbridge (NV) - soil is mixed superactive; xeric moisture regime; formed in residuum and colluvium from quartzite and rhyolite; 10 to 18 percent clay in particle-size control section
Merino (UT) - soil is mixed superactice; udic bordering on ustic moisture regime; O horizon is present, formed in colluvium or residuum derived from monzonite and other granitic rocks, gneiss, tuff, and breccia; no influence of volcanic ash
Sigbird (MT) - soil is mixed superactive; ustic moisture regime; 18 to 27 percent clay in particle-size control section
Treebutte (WA) - xeric moisture regime; O horizon is present, has a mantle of volcanic ash; ash mantle has andic soil properties
GEOGRAPHIC SETTING:
Landform: backslopes to ridges of mountains
Slope gradient: 0 to 60 percent
Parent material: colluvium with an influence of volcaniclastic volcanic ash
Lithology: argillite or rhyolite with and influence of Mazama ash
Elevation: 5,400 to 8,000 feet
Climate: cold, wet winters and cool, dry summers
Mean annual precipitation: 40 to 55 inches
Mean annual air temperature: 31 to 39 degrees F
Frost-free period: 10 to 65 days
GEOGRAPHICALLY ASSOCIATED SOILS:
Vandamine: very deep soil in concave positions on backslopes under closed forest canopy forest
DRAINAGE AND PERMEABILITY:
Drainage: well drained
Permeability: moderately rapid.
USE AND VEGETATION:
Use: watershed, wildlife habitat, livestock grazing and recreation
Native vegetation: open stands of subalpine fir, grand fir, western larch, lodgepole pine, whitebark pine and Douglas fir with and understory of Oregon boxwood, bearberry, creeping Oregon grape, mountain big sagebrush, birchleaf spiraea, fleeceflower, sandworts, phlox, lanceleaf stonecrop, elk sedge and mountain brome.
Plant association: Dominant: ABLA/POPU3 (subalpine fir/skunk leaved polemonium); may include: ABLA/VAME (subalpine fir/big huckleberry) and ABLA/CARU (subalpine fir/pinegrass).
DISTRIBUTION AND EXTENT:
Distribution: Blue Mountains of northeastern Oregon; MLRA 43c
Extent: small
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon
SERIES PROPOSED: Wallowa-Whitman National Forest, Oregon, 2007. The name is from lakes near Halfway, OR.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
ochric epipedon:
cambic horizon: 5 to 14 inches; Bw horizon
ash influenced layer: 0 to 14 inches; A, Bw horizons
particle-size control section: 0 to 14 inches; A, Bw horizons
lithic contact: 14 inches; R