LOCATION MOUNTMCDONALD           AK

Established Series
SAS/MPS
05/2022

MOUNTMCDONALD SERIES

Landscape--mountains
Landform--ridges, mountain slopes
Slope--0 to 40 percent
Parent material--colluvium over residuum
Mean annual precipitation--about 545 mm
Mean annual air temperature--about -4 degrees C
Depth class--shallow
Drainage class--well drained
Soil moisture regime--udic
Soil temperature regime--cryic
Soil moisture subclass--typic

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, shallow Typic Humicryepts

TYPICAL PEDON: MountMcDonald loam on a south southwest facing convex, convex upper third of a mountainflank, on a shoulder, on a slope of 7 percent at an elevation of 563 m (The soil was moist throughout the profile when described on August 8, 2019.)

Oe--0 to 2 cm; gravelly moderately decomposed plant material, dark gray (7.5YR 4/1) dry, black (7.5YR 2.5/1) moist; common very fine, few medium, and common fine roots throughout; 25 percent angular gravel; extremely acid (pH 4.0); abrupt irregular boundary

A1--2 to 10 cm; very gravelly loam, brown (10YR 5/3) dry, dark brown (10YR 3/3) moist; weak medium granular structure; friable, nonsticky, nonplastic; weakly smeary; many very fine and common fine roots throughout; very fine irregular pores; 5 percent angular cobbles, 45 percent angular gravel; moderately acid (pH 5.8); clear irregular boundary

A2--10 to 32 cm; extremely gravelly silt loam, brown (10YR 5/3) dry, dark brown (10YR 3/3) moist; weak medium granular structure; friable, nonsticky, nonplastic; weakly smeary; few very fine roots throughout and few fine roots throughout; fine irregular pores; 30 percent angular cobbles, 45 percent angular gravel; moderately acid (pH 5.6); very abrupt irregular boundary

2Cr--32 to 150 cm;

TYPE LOCATION: Nome Census Area, Alaska, latitude 63.7219539 longitude -160.1234501 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 umbric epipedon--18 to 43 cm
Depth to paralithic contact--25 to 50 cm

Particle Size Control Section:
*Clay--8 to 16 percent
*Total fragments--50 to 85 percent gravels, channers, and cobbles

Oe horizon
Total rock fragment content--0 to 30 percent subangular to angular gravel
Thickness--2 to 7 cm

A1 horizon
Hue--7.5YR or 10YR
Value--2 to 3 moist, 4 or 5 dry
Chroma--2 or 3
Fine-earth texture--silt loam, loam
Clay--6 to 12 percent
Sand--15 to 45 percent
Organic carbon--5 to 12 percent
Total rock fragment content--25 to 60 percent
Total gravel content--25 to 60 percent
Total cobble content--0 to 10 percent
n value--0.3 to 0.7
Reaction--4.9 to 6.0
Thickness--5 to 22 cm

A2 horizon
Hue--7.5YR or 10YR
Value--2 to 3 moist, 4 or 5 dry
Chroma--2 or 3
Fine-earth texture--silt loam, loam
Clay--6 to 16 percent
Sand--15 to 50 percent
Organic carbon--5 to 8 percent
Total rock fragment content--50 to 85 percent
Total gravel content--35 to 65 percent
Total channer content--0 to 25 percent
Total cobble content--0 to 40 percent
n value--0.3 to 0.7
Reaction--5.1 to 6.3
Thickness--8 to 26 cm

2Cr horizon

COMPETING SERIES: None

GEOGRAPHIC SETTING:
*Elevation--30 to 1050 m
*Climate--warm, moist summers; cold, dry winters
*Mean annual precipitation--305 to 745 mm
*Mean annual air temperature-- -6 to -2 degrees C
*Frost-free period--45 to 80 days

GEOGRAPHICALLY ASSOCIATED SOILS:
* Kanguq--moderately deep to paralithic contact, ochric epipedon, cambic horizon; hillslopes and mountain slopes
* Paugna--gelic soil temperature regime, hillslopes and mountain slopes
* Myoukchuk--deep to paralithic contact, ochric epipedon, fragmental particle-size class, hillslopes and mountain slopes
* Bonasila--gelic soil temperature regime, gelic materials, cambic horizon, isotic mineralogy; hillslopes and mountain slopes
* Iprugalet--deep to lithic bedrock; mountain slopes
* Akiuk--ochric epipedon, cambic horizon, ridges on mountains
* Nuvuk--gelic soil temperature regime, folistic epipedon; hillslopes and mountain slopes
* Oliverhill--ochric epipedon, shallow to lithic contact, textures range to sandy loam; similar landscape position
* Iiguk--very deep, ochric epipedon, redox concentrations present; broad hillslopes and mountain slopes
*Casacadecreek--ochric epipedon, cambic horizon, isotic mineralogy class, hillslopes, mountain slopes

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY:
*Drainage class--well drained
*Saturation during normal years--none
*Saturated hydraulic conductivity (Ksat)--very high in the surface organic layer, high to moderately high throughout the profile

USE AND VEGETATION:
Use--wildlife habitat, recreation, subsistence
Potential native vegetation--eightpetal mountain-avens, skeletonleaf willow, locoweed, bryocaulon lichen, witch's hair lichen, snow lichen, globe ball lichen, reindeer lichen, greygreen reindeer lichen, asahinea lichen, alpine sweetgrass, crustose lichen, Bigelow's sedge, white arctic mountain heather, cup lichen, star reindeer lichen, pincushion plant, alpine azalea, blue mountainheath, whiteworm lichen, lingonberry, dwarf birch, Bering Sea sedge, black crowberry, marsh Labrador tea, tomentose lichen, narrowleaf arnica, arctic stitchwort, willow, Moss, golden asahinea lichen, birch, white spruce, Siberian alder, sedge, island cetraria lichen, brackish oxytrope, foliose lichen

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 2 to 32 cm
*Umbric epipedon--zone from 2 to 32 cm
*Paralithic contact--at 32 cm
*Lithilogical discontinuity--at 32 cm

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National Cooperative Soil Survey
U.S.A.