LOCATION PINKHAM                 CO

Established Series
Rev. AJC-JEB-KLS
01/2023

PINKHAM SERIES

The Pinkham series consists of very deep, well drained soils that formed in alluvial fan materials derived from gneiss, schist, and quartzite. These soils are on alluvial fans, glacial moraines, till plains, and mountain slopes. Slopes are 4 to 60 percent or more. Mean annual precipitation is about 460 mm, and mean annual air temperature is about -1 degrees C.

TAXONOMIC CLASS: Loamy-skeletal, isotic Entic Haplocryods

TYPICAL PEDON: Pinkham stony sandy loam - forest. (Colors are for dry soil unless otherwise noted.)

Oi--0 to 5 cm; undecomposed organic material, mostly needles, bark, and twigs.

Oe--5 to 8 cm; partially decomposed organic material like that of the horizon above.

E--8 to 18 cm; light brownish gray (10YR 6/2) stony fine sandy loam, grayish brown (10YR 5/2) moist; moderate thin platy structure that parts to fine granules; soft, very friable, nonsticky, nonplastic; 15 percent stones; strongly acid (pH 5.4); abrupt smooth boundary. (5 to 20 cm thick)

Bs--18 to 43 cm; brown (7.5YR 5/4) very stony sandy loam, brown (7.5YR 4/4) moist; weak fine subangular blocky structure that parts to medium granules; slightly hard, very friable, nonsticky, nonplastic; 20 percent stones; many dark concretions and pellets presumed to be manganese and iron humates; strongly acid (pH 5.4); gradual wavy boundary. (15 to 46 cm thick)

C--43 to 160 cm; brown (10YR 5/3) extremely stony sandy loam, brown (10YR 4/3) moist; massive; slightly hard, very friable, nonsticky, nonplastic; 40 percent stones; strongly acid (pH 5.4).

TYPE LOCATION: Jackson County, Colorado; about 305 meters below timberline on the small trail leading to the Michigan Lake Basin T. 6 N., R. 76 E.

RANGE IN CHARACTERISTICS:
Mean annual soil temperature--1 degree C
Mean summer soil temperature--6 degrees C
Solum thickness--20 to 75 cm
In some pedons a very thin and inconsistent A horizon is present.

Particle-size control section:
Texture--extremely stony sandy loam
Clay content--5 to 18 percent
Sand content--52 to 82 percent with more than 35 percent fine or coarser sand
Rock fragment content--0 to 35 percent in a major part of the solum but increasing with depth. In the lower part of the control section, fragments range from 35 to 75 percent that are mainly 250 to 600 mm in diameter.

E horizon
Hue--5Y through 7.5YR
Value--5 through 8 dry, 4 through 7 moist
Chroma of 1 through 4
Structure--weak to moderate platy structure that separates to granular structure
Reaction--pH 5.1 to 6.0

Bs horizon
Hue--7.5YR through 2.5YR
Value--5 through 7 dry, 4 through 6 moist
Chroma--2 through 6
Reaction--pH 4.5 to 5.5

C horizon
Hue--5Y through 7.5YR
Reaction--pH 4.5 to 6.0

COMPETING SERIES: These are the Arrow, Darling, Holroyd, and Nambe series. Arrow soils have a lithic contact at depths of 50 to 100 cm. Darling soils have fewer than 35 percent rock fragments throughout the control section. Holroyd soils have control sections with more than 18 percent clay and have fewer than 35 percent rock fragments throughout. Nambe soils lack an albic horizon.

GEOGRAPHIC SETTING:
Landform--alluvial fans, glacial moraines, till plains, and mountain slopes
Elevation--2900 to 3350 meters
Slope--4 to 60 percent or more
Parent material--noncalcareous alluvial fan materials derived from gneiss, schist, and quartzite
Mean annual precipitation--460 mm, with peak periods of precipitation in the spring and early summer months
Mean annual air temperature--minus 1 to 2 degrees C
Mean summer air temperature--6 degrees C
Frost-free period--10 to 20 days

GEOGRAPHICALLY ASSOCIATED SOILS: None listed

DRAINAGE AND PERMEABILITY: Well drained; slow runoff; rapid permeability

USE AND VEGETATION: They are used as native pastureland, for forestry, and for recreation. Native vegetation is spruce, fir, and a weak understory of shrubs and grass.

DISTRIBUTION AND EXTENT: Pinkham soils are moderately extensive in the mountains of northcentral Colorado; MLRA 48A.

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Bozeman, Montana

SERIES ESTABLISHED: Jackson County, Colorado, 1973

REMARKS: Converted to metric and O horizons were updated to start at zero. Competing series section was not updated. 01/2023

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National Cooperative Soil Survey
U.S.A.