LOCATION SHEEPISLAND             AK

Established Series
SAS/TJR/SJN
02/2022

SHEEPISLAND SERIES

The Sheepisland series consists of very deep, very poorly drained soils formed in mossy organic parent material over silty marine deposits. Slopes range from 0 to 3 percent. The mean annual precipitation is about 615 millimeters and the mean annual air temperature is about 0.6 degrees C.

TAXONOMIC CLASS: Loamy, mixed, euic Terric Cryofibrists

TYPICAL PEDON: Sheepisland peat, located on a coastal plain with a slope of 1 percent and elevation of 8 meters; when described on July 27th, 2007 the soil was saturated throughout (Colors are for moist soil unless otherwise noted)

Oi1--0 to 54 cm; peat; many very fine and fine roots, many medium roots, and common coarse roots; strongly acid (pH 5.4); clear wavy boundary

Oi2--54 to 110 cm; peat; many very fine and fine roots, many medium roots, and common coarse roots; strongly acid (pH 5.4); gradual wavy boundary

Cg--110 to 183 cm; 85 percent dark greenish gray (10Y 3/1) silt; 13 percent sand; 80 percent silt; 7 percent clay; massive; friable, nonsticky, nonplastic; few very fine and fine roots, few medium roots, and few coarse roots; 15 percent medium very dark gray (N 3/) moist, masses of reduced iron with clear boundaries; slightly acid (pH 6.1)

TYPE LOCATION: Dillingham Census Area, Alaska; 2 km northeast of the city center of the City of Dillingham; 59.0597222 degrees north latitude and 158.440000 degrees west longitude.

RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 0.8 to 2.4 degrees C (cryic soil temperature regime)
Soil moisture control section - Soil is at the soil surface for much of the growing season in most years (aquic soil moisture regime)
Thickness of fibric soil material - 94 to 110 cm
Depth to aquic conditions - 0 cm
Depth to reduced matrix - 94 to 110 cm

All mineral horizons-
Reaction - 6.1 to 7.4

Particle-size control section-
Clay content - 4 to 10 percent
Rock fragments - 0 percent

Oi horizons
Combined thickness - 94 to 110 cm
Reaction - 5.4 to 7.2
Rock fragments - 0 percent

Cg horizon
Hue - 10Y, 2.5Y, or N
Value - 3 to 6
Chroma - 1
Fine earth texture - Silt or silt loam
Clay content - 4 to 10 percent
Reaction - 6.1 to 7.4
Rock fragments - 0 percent
Thickness - 73 to 89 cm

COMPETING SERIES:
Clunie - pH ranges to below 6 in the C horizon, C horizon ranges to silty clay loam
Hufman - Formed in organic material over stratified stream alluvium on stream terraces and palsas

GEOGRAPHIC SETTING:
Parent material - Mossy organic material
Landform - Coastal plains, talfs
Slope - 0 to 1 percent
Elevation - 1 to 10 meters
Climate - Cool summers; cold winters, August and September are the wettest months
Mean annual precipitation - 610 to 619 mm
Mean annual air temperature - 0.4 to 0.7 degrees C
Frost free duration - 85 to 140 days

GEOGRAPHICALLY ASSOCIATED SOILS:
Ekuk - No aquic conditions, formed in sandy and gravelly fluviomarine deposits, coastal plains
Mudie - Aquic conditions within 25 cm, formed in silty marine deposits, similar landform position
Ustiugof - Aquic conditions within 25 cm, formed in silty marine deposits over sandy and gravelly marine deposits, similar landform position
Flounder - Aquic conditions within 25 cm, formed in silty colluvium and gravelly glacial till, bluffs

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: (Ksat)
Drainage class - Very poorly drained
Saturation in normal years - At the soil surface for most months
Flooding - Very rare
Ponding - Frequent and very long
Ksat - Moderately high to high in the organic soil material, moderately high in the marine deposits

USE AND VEGETATION:
Use - Wildlife habitat
Potential natural vegetation - Western Alaska maritime scrubland composed of sweetgale, dwarf birch, leatherleaf, sedges, bluejoint grass, purple marshlocks and sphagnum moss

DISTRIBUTION AND EXTENT: Bristol Bay Lowlands; MLRA 236; small extent

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

SERIES ESTABLISHED: Nushagak-Mulchatna Watershed Soil Survey, Dillingham Census Area, Alaska, 2019

REMARKS:
Particle-size control section - 110 to 160 cm
Soil moisture regime - Aquic
Aquic soil conditions - All soil horizons
Reduced matrix - Cg horizon

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National Cooperative Soil Survey
U.S.A.