LOCATION PURCHES                 AK

Inactive Series
Rev. DBS/DJVP
02/2022

PURCHES SERIES

The Purches series consists of moderately well drained to somewhat poorly drained soils formed in glacial till capped with a loess mantle. They occur in slight depressions in glacial moraines and on muskeg borders and have slopes of 0 to 12 percent. Mean annual precipitation is about 15 inches and mean annual air temperature is 35 degrees F.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive Typic Cryaquods

TYPICAL PEDON: Purches silt loam,forest. (Colors are for moist soil).

01--3 to 2 inches; partially decomposed forest litter.

02--2 to 0 inches; black (10YR 2/1) decomposed forest litter; very strongly acid: abrupt smooth boundary. (1 to 2 inches thick)

A1--0 to 1 inches, black (10YR 2/1) mucky silt loam; moderate medium granular structure; very friable; very strongly acid; clear wavy boundary. (0 to 2 inches thick)

A2--1 to 3 inches; gray (5Y 5/1) silt loam; moderate medium granular structure; very friable; strongly acid; clear smooth boundary. (1 to 2 inches thick)

B2--3 to 12 inches; dark brown (7.5YR 4/4) silt loam; many large distinct grayish brown mottles; moderate fine granular structure, very friable; few pebbles; strongly acid. (6 to 10 inches thick)

IIC1--12 to 24 inches; grayish brown (2.5Y 5/2) gravelly sandy loam; common medium distinct olive brown mottles; moderate medium subangular blocky structure; friable; about 20 percent gravel; strongly acid; (10 to 14 inches thick)

IIC2--24 to 40 inches; grayish brown (2.5Y 5/2) very gravelly sandy loam; massive; firm; about 60 percent gravel and cobbles; strongly acid.

TYPE LOCATION: Anchorage Area, Alaska; S. E. corner of NW 1/4 NW 1/4 of Sec. 23, T.14N., R.3W., Seward Meridian.

RANGE IN CHARACTEISTICS: The loess mantle ranqes from 10 to 19 inches in thickness. Some pedons have no A1 horizon. The A2 horizon ranges from gray to dark gray or dark grayish brown. (5Y 5/1 or 10YR 5/1 to 10YR 4/1 and 4/2). It is not mottled in all pedons.

The B2 horizon ranges from dark yellowish brown to brown or dark brown (10YR 4/4 to 7.5YR 4;/4 or 4/3). Mottles are dark reddish brown, grayish brown, and olive brown. Gravel content ranges from 0 to 20 percent.

The IIC horizon is dark gray, olive gray, or olive to grayish brown (5Y 4/1, 5/2, 4/3 to 2.5Y 5/2). Texture is typically very gravelly silt loam and very gravelly sandy loam. Gravel content ranqes from 40 to 60 percent.

COMPETING SERIES: These are Grewingk, Homestead, Lucile, and Spenard. The Grewingk soils have a thick organic mat on the surface and a spodic horizon that extends no deeper than 7 inches, and have less than 35 percent coarse fragments in the 10 to 40 inch section. Homestead soils have spodic horizons without mottles. Lucile soils have a bisequal solum formed in silt loam loess 15 to 24 inches thick. Spenard soils have less than 35 percent gravel in the control section.

GEOGRAPHIC SETTING: The Purches soils occur in slight depressions in glacial moraines and on muskeg borders. They have slopes of 0 to 12 percent. Elevations are between 50 and 1000 feet. Mean annual precipitation ranges from about 14 to 20 inches and mean annual air temperature is about 35 degrees F. The average frost-free period is about 115 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Homestead soils and the Doroshin, Jacobsen, and Kasilof soils. The Doroshin soils consist of peat 18 to 51 inches thick. The Jacobsen soils are formed in very stony water worked material. The Kasilof soils have sandy-skeletal texture below 10 inches and the spodic horizon is not mottled.

DRAINAGE AND PERMEABILITY: Moderately well drained to somewhat poorly drained; slow to medium runoff, moderately slow permeability.

USE AND VEGETATION: The soils are mostly covered by black spruce forest. A few areas have been used for dwellings.

DISTRIBUTION AND EXTENT: Cook Inlet-Susitna Lowland, Alaska; moderately extensive.

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

SERIES PROPOSED: Anchorage Area, alaska, 1976. (Source of name is Purches CreeK .

OSED scanned by SSQA. Last revised by state on 01/77.

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National Cooperative Soil Survey
U.S.A.