LOCATION UNICORNPEAK             WA

Established Series
IRD. TMR/MPR
07/2017

UNICORNPEAK SERIES

Landscape--Cascade Mountains
Landform--cirques, debris aprons, glacial valley walls
Slope--0 to 65 percent
Parent material--volcanic ash over colluvium
Mean annual precipitation--about 2200 mm
Mean annual air temperature--about 3 degrees C
Depth class--very deep
Drainage class--moderately well drained
Soil moisture regime--udic
Soil temperature regime--cryic
Soil moisture subclass--aquic

TAXONOMIC CLASS: Medial, glassy Aquandic Haplocryods

TYPICAL PEDON: Unicornpeak medial sandy loam on a west-facing, forested debris apron with a slope of 5 percent and at an elevation of 1540 m (When described on September 19, 2013, the soil was moist throughout.)

Oi--0 to 2 cm; slightly decomposed plant material from deciduous shrubs, conifer needles, and twigs; many fine interstitial pores; very strongly acid (pH 4.5); abrupt smooth boundary

Oe--2 to 6 cm; moderately decomposed plant material; common very fine to coarse roots; many fine interstitial pores; very strongly acid (pH 4.5); abrupt wavy boundary

E--6 to 12 cm; medial sandy loam, gray (7.5YR 6/1) dry, very dark gray (7.5YR 3/1) moist; moderate fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine to very coarse roots; common very fine and fine interstitial pores; 5 percent pumice paragravel; very strongly acid (pH 4.7); abrupt wavy boundary

Bs1--12 to 32 cm; medial sandy loam, brown (7.5YR 4/3) dry, dark brown (7.5YR 3/3) moist; moderate fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; common very fine to coarse roots; common very fine and fine interstitial pores; 10 percent pumice paragravel; strongly acid (pH 5.2); abrupt irregular boundary

Bs2--32 to 58 cm; medial coarse sandy loam, brown (7.5YR 5/4) dry, dark brown (7.5YR 3/4) moist; moderate fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; few very fine to medium roots; common very fine and fine irregular pores; 5 percent pumice paragravel; strongly acid (pH 5.2); clear wavy boundary

Bg1--58 to 72 cm; medial fine sandy loam, brown (10YR 5/3) dry, dark brown (10YR 3/3) moist; moderate medium subangular blocky structure; slightly hard, friable, nonsticky and nonplastic; few very fine to medium roots; common very fine and fine irregular pores; 25 percent medium dark grayish brown (10YR 4/2) iron depletions with clear boundaries in matrix and 25 percent medium dark yellowish brown (10YR 3/4) masses of oxidized iron with diffuse boundaries in matrix; 5 percent andesite gravel; strongly acid (pH 5.2); clear irregular boundary

Bg2--72 to 88 cm; medial fine sandy loam, light brown (7.5YR 6/4) dry, brown (7.5YR 4/4) moist; moderate medium subangular blocky structure; slightly hard, friable, nonsticky and nonplastic; few very fine to medium roots; common very fine and fine irregular pores; 5 percent fine grayish brown (10YR 5/2) iron depletions with clear boundaries in matrix and 25 percent medium dark yellowish brown (10YR 3/6) masses of oxidized iron with clear boundaries in matrix; 10 percent andesite gravel; strongly acid (pH 5.4); gradual wavy boundary

2Bg3--88 to 150 cm; gravelly medial fine sandy loam, brown (10YR 5/3) dry, dark brown (10YR 3/3) moist; moderate medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; few very fine to medium roots; few very fine and fine irregular pores; 2 percent fine dark grayish brown (10YR 4/2) iron depletions with clear boundaries in matrix and 25 percent medium strong brown (7.5YR 4/6) masses of oxidized iron with clear boundaries in matrix; 20 percent andesite gravel and 10 percent andesite cobbles; strongly acid (pH 5.4)

TYPE LOCATION: Pierce County, Washington, about 2 km southwest of Lake Eleanor and 5 km east of Oliver Lake, in an unnamed drainageway in Mount Rainier National Park; about 60 m south and 430 m east of the northwest corner of section 9, T. 17 N., R. 9 E., Willamette Meridian; Sunrise, Washington, U.S. Geological Survey quadrangle; latitude 46.979433 degrees north, longitude -121.678175 degrees west, datum WGS 84 (coordinates determined with a GPS)

RANGE IN CHARACTERISTICS:
Mean annual soil temperature--3 to 6 degrees C
Soil moisture control section--dry less than 45 consecutive days in June through October
Depth to lithologic discontinuity--70 to 90 cm
Depth to redoximorphic iron depletions--50 to 75 cm below the mineral soil surface

All mineral horizons
*Volcanic glass content--50 to 75 percent
*Ammonium oxalate Al plus 1/2 Fe--greater than 0.5 percent
*Organic carbon content--less than 6 percent

Particle-size control section
*Clay content--1 to 10 percent
*Pararock and rock fragment content--5 to 35 percent total, with pumice paragravel typically in upper part of profile and andesite gravel and cobbles in lower part in some areas

O horizon
*In lieu of texture--slightly decomposed plant material, moderately decomposed plant material
*Combined thickness--5 to 10 cm

E horizon
*Hue--7.5YR, 10YR
*Value--3 to 5 moist, 5 to 7 dry
*Chroma--1 or 2 moist or dry
*Fine-earth texture--medial sandy loam, medial loamy sand
*Pararock fragment content--0 to 15 percent pumice paragravel
*Reaction--4.5 to 5.5
*Thickness--5 to 15 cm

Bs1 horizon
*Hue--7.5YR, 5YR, 10YR
*Value--2 to 4 moist, 4 to 6 dry
*Chroma--2 to 4 moist or dry
*Fine-earth texture--medial sandy loam, medial fine sandy loam, medial coarse sandy loam
*Pararock fragment content--0 to 25 percent pumice paragravel
*Reaction--4.5 to 5.5
*Thickness--15 to 30 cm

Bs2 horizon
*Hue--7.5YR, 10YR
*Value--3 or 4 moist, 4 to 6 dry
*Chroma--2 to 4 moist or dry
*Fine-earth texture--medial coarse sandy loam, medial loamy sand, medial sandy loam
*Pararock fragment content--0 to 25 percent pumice paragravel
*Reaction--4.5 to 5.5
*Thickness--25 to 40 cm

Bg1 and Bg2 horizons
*Hue--7.5YR, 10YR
*Value--3 or 4 moist, 4 to 6 dry
*Chroma--2 to 4 moist or dry
*Fine-earth texture--medial fine sandy loam, medial sandy loam
*Pararock and rock fragment content--5 to 35 percent total, including 0 to 25 percent pumice paragravel and 5 to 10 percent gravel
*Reaction--5.1 to 6.0
*Combined thickness--30 to 50 cm

2Bg3 horizon
*Hue--10YR, 7.5YR
*Value--3 to 5 moist, 5 to 7 dry
*Chroma--2 to 4 moist or dry
*Fine-earth texture--medial fine sandy loam, medial coarse sandy loam, medial loam
*Rock fragment content--15 to 45 percent total, including 10 to 30 percent gravel, 0 to 15 percent cobbles, and 0 to 5 percent stones
*Reaction--5.1 to 6.0

COMPETING SERIES: None

GEOGRAPHIC SETTING:
Elevation--1000 to 2000 m
Climate--cool, dry summers; cold, wet winters
Mean annual precipitation--1700 to 2800 mm
Mean annual air temperature--2 to 5 degrees C
Frost-free period--30 to 60 days

GEOGRAPHICALLY ASSOCIATED SOILS:
Ipsut--no aquic conditions; lithic contact within 50 cm (shallow); on similar landforms with steeper slopes and Rock outcrop near the surface
Owyhigh--no aquic conditions; lithic contact within 100 cm (moderately deep); on similar landforms with steeper slopes and Rock outcrop near the surface
Tipsoo--no aquic conditions; in similar landform positions with steeper slopes
Mysticlake--aquic conditions with an upper limit of 25 cm from the mineral soil surface; on similar landforms in gentler sloping positions that receive runoff from upslope areas
Summerland--umbric epipedon; no albic horizon; associated with deciduous forests in active avalanche paths
Burroughs, Littletahoma, Tatoosh--umbric epipedon; no albic horizon; associated with subalpine meadows on similar landforms

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
Drainage class--moderately well drained
Saturation in normal years--below 50 to 100 cm in December through June, below 100 to 180 cm in July through October
Saturated hydraulic conductivity (Ksat)--high or very high throughout

USE AND VEGETATION:
Use--wildlife habitat, recreation
Potential natural vegetation--subalpine fir, mountain hemlock, Pacific silver fir, Alaska yellow-cedar, Engelmann spruce, Cascade azalea, black huckleberry, false azalea, five-leaved bramble, dwarf bramble, one-sided wintergreen, Sitka valerian, common beargrass

DISTRIBUTION AND EXTENT: Central Cascade Mountains, Washington; MLRA 3; moderate extent

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

SERIES ESTABLISHED: Mount Rainier National Park, Pierce County, Washington; 2014; name from Unicorn Peak in Mount Rainier National Park

REMARKS:
Diagnostic horizons and other features in this pedon
*Particle-size control section--zone from 31 to 106 cm
*Ochric epipedon
*Albic horizon--zone from 6 to 12 cm
*Spodic horizon--zone from 12 to 58 cm
*Andic soil properties--zone from 6 to 150 cm
*Redoximorphic iron depletions with chroma of 2 or less--zone from 58 to 150 cm
*Redoximorphic iron concentrations--zone from 58 to 150 cm
*Depth to lithologic discontinuity--88 cm
*Distinguishable tephra layers--Mount St. Helens Wn tephra (E horizon), Mount Rainier C tephra (Bs1 horizon), Mount St. Helens Yn tephra (Bs2 horizon), Mount Rainier F tephra (Bg1 horizon), Mount Mazama O tephra (Bg2 horizon)

3/2017--This official series description was updated according to SSR1 Technical Note 11--Content and Format of Official Series Descriptions (revised 12/2015). Most of the changes were in formatting; no major technical changes were made.

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National Cooperative Soil Survey
U.S.A.