LOCATION SKYMO WA

Established Series
Rev. TMR/SBC
01/2023

SKYMO SERIES

The Skymo series consists of very deep, moderately well drained soils formed in alluvium. Skymo soils are found on slopes of 0 to 5 percent on flood plains and terraces of river valley bottoms. The mean annual precipitation is about 1,900 millimeters and the mean annual air temperature is about 7 degrees C.

TAXONOMIC CLASS: Sandy, isotic, frigid Oxyaquic Udifluvents

TYPICAL PEDON: Skymo coarse sand, located on a forested south facing floodplain with a slope of 0 percent and an elevation of 130 meters. When described on June 10, 2008 the soil was moist throughout. (Colors are for moist soil unless otherwise noted)

Oi--0 to 2 cm; slightly decomposed leaves, twigs, and needles; common medium irregular pores; abrupt wavy boundary.

C--2 to 10 cm; grayish brown (2.5Y 5/2) coarse sand, light brownish gray (2.5Y 6/2) dry; single grain; loose, nonsticky, nonplastic; few very fine to medium roots; many fine to medium interstitial pores; strongly acid (pH 5.5); abrupt wavy boundary.

Ab--10 to 16 cm; dark grayish brown (10YR 4/2) loamy sand, grayish brown (10YR 5/2) dry; weak fine subangular blocky structure; loose, nonsticky, nonplastic; many very fine and common fine to coarse roots; common fine to medium irregular pores; strongly acid (pH 5.1); abrupt wavy boundary.

C'--16 to 34 cm; light olive brown (2.5Y 5/3) sand, light yellowish brown (2.5Y 6/3) dry; single grain; loose, nonsticky, nonplastic; many very fine to fine and common medium to coarse roots; common fine to medium interstitial pores; strongly acid (pH 5.2); abrupt irregular boundary.

Ab'--34 to 40 cm; very dark grayish brown (10YR 3/2) sandy loam, grayish brown (10YR 5/2) dry; weak medium subangular blocky structure; soft, very friable, nonsticky, nonplastic; few very fine and common fine to coarse roots; common fine to medium irregular pores; strongly acid (pH 5.1); abrupt wavy boundary.

Bwb1--40 to 45 cm; dark olive brown (2.5Y 3/3) loamy sand, light olive brown (2.5Y 5/3) dry; weak fine subangular blocky structure; loose, nonsticky, nonplastic; few very fine to fine and common medium to coarse roots; many fine to medium interstitial pores; strongly acid (pH 5.2); clear wavy boundary.

Bwb2--45 to 66 cm; very dark grayish brown (10YR 3/2) loamy sand, grayish brown (10YR 5/2) dry; weak medium subangular blocky structure; soft, very friable, nonsticky, nonplastic; few coarse and very fine to fine, common medium roots; common fine to medium irregular pores; strongly acid (pH 5.5); clear wavy boundary.

Bwb3--66 to 90 cm; very dark grayish brown (2.5Y 3/2) loamy sand, grayish brown (2.5Y 5/2) dry; weak fine subangular blocky structure; soft, very friable, nonsticky, nonplastic; few very fine to coarse roots; common fine to medium irregular pores; 10 percent fine faint irregular grayish brown (2.5Y 5/2) iron depletions with sharp boundaries in matrix, and 20 percent medium faint irregular yellowish brown (10YR 5/4) masses of oxidized iron with clear boundaries in matrix; moderately acid (pH 5.6); clear irregular boundary.

C''--90 to 152 cm; dark olive brown (2.5Y 3/3) gravelly sand, light olive brown (2.5Y 5/3) dry; single grain; loose, nonsticky, nonplastic; few very fine to medium roots; common medium to coarse interstitial pores; 10 percent fine faint irregular grayish brown (2.5Y 5/2) iron depletions with sharp boundaries in matrix and 30 percent medium faint irregular yellowish brown (10YR 5/4) masses of oxidized iron with clear boundaries in matrix; 5 percent rounded fine gravel, 15 percent rounded medium and coarse gravel, and 10 percent rounded cobbles; slightly acid (pH 6.1).

TYPE LOCATION: Skagit County, Washington; approximately 8 km southwest of the town of Newhalem, along the Skagit River near Sky Creeks, North Cascades National Park Service Complex; 290 meters west and 25 meters south of the northeast corner of section 11, T. 36 N., R. 11 E. Willamette Meridian; Mount Triumph, Washington USGS quadrangle; 48 degrees, 37 minutes, 39 seconds north latitude and 121 degrees, 19 minutes, 57 seconds west longitude; UTM 622865 meters E, 5387420 meters N, zone 10N.

RANGE IN CHARACTERISTICS:
Mean annual soil temperature 5 to 8 degrees C. Frigid soil temperature regime.
Moisture control section - dry 30 to 45 consecutive days. Udic soil moisture regime.
Depth to redoximorphic concentrations - 50 to 100 cm
Particle-size control section:
Clay content - 0 to 8 percent
Rock fragments - 0 to 30 percent total, 0 to 30 percent fine to coarse gravel, 0 to 25 percent cobbles

C horizon
Hue - 2.5Y, 10YR, or variegated mineral colors
Value - 3 to 5 moist, 4 to 6 dry
Chroma - 2 to 4 moist or dry
Fine earth texture - COS, S
Rock fragments - 0 to 10 percent fine gravel
Reaction - strongly acid to moderately acid
Thickness - 5 to 15 centimeters (may not be present in all pedons)

Ab and Ab' horizons
Hue - 10YR or 7.5YR
Value - 3 to 4 moist, 4 to 5 dry
Chroma - 2 to 3 moist or dry
Fine earth texture - SL, LS, S, LFS
Rock fragments - 0 to 30 percent total, 0 to 30 percent fine to coarse gravel, 0 to 15 percent cobbles
Reaction - strongly acid to moderately acid
Thickness - 2 to 15 centimeters

C' and C'' horizons
Hue - 2.5Y or variegated mineral colors
Value - 3 to 5 moist, 4 to 6 dry
Chroma - 2 to 4 moist or dry
Fine earth texture - S, COS, LS, LCOS
Rock fragments - 0 to 30 percent total, 0 to 30 percent fine to coarse gravel, 0 to 15 percent cobbles
Reaction - strongly acid to moderately acid
Thickness - 5 to 25 centimeters typically, but ranging to 70 cm lower in profile

Bw horizons
Hue - 10YR or 2.5Y
Value - 3 to 5 moist, 4 to 6 dry
Chroma - 2 to 4 moist or dry
Fine earth texture - LS, LCOS, COS, S
Rock fragments - 0 to 30 percent total, 0 to 30 percent fine to coarse gravel, 0 to 15 percent cobbles
Reaction - moderately acid to strongly acid

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING: Skymo soils are found on slopes of 0 to 5 percent on floodplains and terraces of river valley bottoms at elevations from 100 to 600 meters. They formed in sandy alluvium of river deposits. The climate is characterized by warm, dry summers and cold, wet winters. Mean annual precipitation ranges from 1,300 to 2,500 millimeters. Mean annual air temperature ranges from 4 to 8 degrees C. Frost-free season is 60 to 90 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Deerlick, Nohokomeen, and Roland soils. Deerlick soils have andic soil material greater than 35 cm thick and a cambic horizon. Nohokomeen soils are in an Aquandic subgroup, have ashy textural modifiers in the upper part of the particle-size control section, a cambic horizon, and redoximorphic features within 45 cm of the soil surface. Roland soils have a cambic horizon and redoximorphic features within 45 cm of the soil surface

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Moderately well drained; high to very high saturated hydraulic conductivity.

USE AND VEGETATION: Skymo soils support wildlife habitat, recreation, and watershed drainage. Native vegetation includes black cottonwood, western hemlock, western redcedar, red alder, bigleaf maple, vine maple, salmonberry, thimbleberry, western swordfern, starry false solomon's seal, sweet-scented bedstraw, and foamflower.

DISTRIBUTION AND EXTENT: North Cascade Mountains, Washington. MLRA 3. Series is of small extent.

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

SERIES ESTABLISHED: North Cascades National Park Service Complex, Skagit County, Washington, 2011.

REMARKS: Diagnostic horizons and features recognized in this pedon include:
Particle-size control section - 2 to 102 cm (25 to 100 cm from the mineral surface)
Ochric epipedon - the zone from 0 to 18 cm (Oi, C1, and upper 2 cm of Ab horizon)
Redoximorphic concentrations - 66 to 152 cm

National Cooperative Soil Survey
U.S.A.