LOCATION MYOUKCHUK               AK

Established Series
SAS/MPS
05/2022

MYOUKCHUK SERIES

Landscape--mountains
Landform--mountain slopes
Slope--20 to 85 percent
Parent material--gravelly colluvium and/or residuum
Mean annual precipitation--about 535 mm
Mean annual air temperature--about -4 degrees C
Depth class--deep to paralithic contact
Drainage class--well drained
Soil moisture regime--udic
Soil temperature regime--cryic
Soil moisture subclass--typic

TAXONOMIC CLASS: Fragmental, mixed Typic Cryorthents

TYPICAL PEDON: Myoukchuk extremely cobbly silt loam on a northwest facing linear, concave backslope on a slope of 59 percent at an elevation of 577 m (The soil was dry throughout when described on August 4, 2019.)

Oi--0 to 5 cm; very cobbly slightly decomposed plant material, dark gray (10YR 4/1) dry, black (10YR 2/1) moist; many very fine roots and fine roots; 5 percent subangular gravel, 40 percent subangular cobble, 5 percent subangular stone; strongly acid (pH 5.3); abrupt irregular boundary

A--5 to 15 cm; extremely cobbly silt loam, dark grayish brown (10YR 4/2) dry, very dark brown (10YR 2/2) moist; weak medium granular structure; friable, nonsticky, nonplastic; many very fine and fine roots; common fine irregular pores; 35 percent subangular gravel, 45 percent angular cobble; moderately acid (pH 5.8); abrupt irregular boundary

C1--15 to 65 cm; cobble, variegated; structureless single grain; loose, nonsticky, nonplastic; 35 percent subangular gravel, 55 percent subangular cobble; moderately acid (pH 5.8); abrupt irregular boundary

C2--65 to 110 cm; gravel, variegated; structureless single grain; loose, nonsticky, nonplastic; 60 percent subangular gravel, 35 percent subangular cobble; moderately acid (pH 5.8); abrupt irregular boundary

Cr--110 to 150 cm; bedrock

TYPE LOCATION: Yukon-Koyukuk Census Area, Alaska, latitude 63.6852704 longitude, -160.3422527 degrees, datum WGS84 (coordinates determined with a GPS unit)

RANGE IN CHARACTERISTICS:
Mean annual soil temperature-- -1 to 3 degrees C
Soil moisture control section--dry less than 45 consecutive days in June through October (udic soil moisture regime)
Thickness of ochric epipedon--3 to 16 cm
Depth to paralithic contact--100 to 150 cm

Particle Size Control Section:
*Total fragments--90 to 100 percent angular gravels or cobbles

Oi horizon
Total rock fragment content--0 to 50 percent
Total gravel content--0 to 45 percent
Total cobble content--0 to 40 percent
Total stone content--0 to 5 percent
Thickness--2 to 6 cm

A horizon
Hue--7.5YR or 10YR
Value--2 to 3 moist, 4 to 5 dry
Chroma--2 to 4
Fine-earth texture--silt, silt loam
Clay--2 to 10 percent
Sand--15 to 40 percent
Organic carbon--3 to 5 percent
Total rock fragment content--55 to 85 percent
Total gravel content--35 to 70 percent
Total cobble content--15 to 45 percent
Total flagstone content--0 to 5 percent
Reaction--5.1 to 6.0
Thickness--2 to 10 cm

C1 and C2 horizon
In lieu of texture--gravels, cobbles, or flagstones
Total rock fragment content--90 to 100 percent
Total gravel content--35 to 75 percent
Total cobble content--25 to 60 percent
Combined thickness--84 to 147 cm

Cr horizon

COMPETING SERIES: none

GEOGRAPHIC SETTING:
*Elevation--50 to 950 m
*Climate--warm, moist summers; cold, dry winters
*Mean annual precipitation--405 to 630 mm
*Mean annual air temperature-- -6 to -2 degrees C
*Frost-free period--45 to 80 days

GEOGRAPHICALLY ASSOCIATED SOILS:
* Paugna--umbric epipedon, gelic soil temperature regime, loamy-skeletal particle-size class, hillslopes and mountain slopes
* Kanguq--isotic mineralogy, cambic horizon, loamy-skeletal particle-size class, hillslopes and mountain slopes
*MountMcDonald--shallow to paralithic bedrock, umbric epipedon; mountain slopes
* Oliverhill--ochric epipedon, shallow to lithic contact, textures range to sandy loam; mountain slopes

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
*Drainage class--well drained
*Saturation during normal years--none
*Saturated hydraulic conductivity (Ksat)--very high in the organic soil layers and in the fragmental soil layers, moderately high throughout the A horizon

USE AND VEGETATION:
Use--wildlife habitat, recreation, subsistence
Potential native vegetation--quaking aspen, black crowberry, lingonberry, Siberian alder, racomitrium moss, frafrant woodfern, fireweed, snow lichen, crustose lichen, reindeer lichen, star reindeer lichen, greygreen reindeer lichen, Moss, arctic willow, alpine sweetgrass, cup lichen, common woodrush, juniper polytrichum moss, white arctic mountain heather, eightpetal mountain-avens, smallawned sedge, rhytidium moss, dicranum moss

DISTRIBUTION AND EXTENT: Nulato Hills-Southern Seward Peninsula Highlands, Alaska; MLRA 240; moderate extent

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: WASILLA, ALASKA

SERIES ESTABLISHED: Nulato Hills BLM area, Nome Census Area, Alaska; 2021

REMARKS:
Diagnostic horizons and features recognized in this pedon
*Particle-size control section--zone from 30 to 105 cm
*Ochric epipedon--zone from 0 to 15 cm
*Paralithic contact--110 cm

---

National Cooperative Soil Survey
U.S.A.