LOCATION PINKHAM COEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, isotic Entic Haplocryods
TYPICAL PEDON: Pinkham stony sandy loam - forest. (Colors are for dry soil unless otherwise noted.)
01--3 to 1 inches; undecomposed organic material, mostly needles, bark, and twigs.
02--1 inch to 0; partially decomposed organic material like that of the horizon above.
A2--0 to 4 inches; light brownish gray (1OYR 6/2) stony fine sandy loam, grayish brown (1OYR 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. (2 to 8 inches thick)
B2ir--4 to 14 inches; brown (7.5YR 5/4) very stony sandy loam, dark 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. (6 to 18 inches thick)
C--14 to 60 inches; brown (1OYR 5/3) extremely stony sandy loam, dark brown (1OYR 4/3) moist; massive; slightly hard, very friable, nonsticky, nonplastic; 40 percent stones; strongly acid (pH 5.4).
TYPE LOCATION: Jackson County, Colorado; approximately 1,000 feet 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 is about 34 degrees F. and mean summer soil temperature is about 43 degrees F. In some pedons a very thin and inconsistent A1 horizon is present. The solum ranges from 8 to 30 inches thick. The control section is typically extremely stony sandy loam but clay ranges from 5 to 18 percent, silt from 5 to 35 percent, and sand from 52 to 82 percent with more than 35 percent fine or coarser sand. Rock fragments range from 0 to 35 percent in a major part of the solum but increase with depth to range from 35 to 75 percent in the lower part of the control section. These are mainly 10 to 24 inches in diameter.
The A2 horizon has hue of 5Y through 7.5YR, value of 5 through 8 dry, 4 through 7 moist, and chroma of 1 through 4. It has weak to moderate platy structure that separates to granular structure. This horizon ranges from very strongly acid to medium acid.
The B2ir horizon has hue of 7.5YR through 2.5YR, value of 5 through 7 dry, 4 through 6 moist, and chroma of 2 through 6. It is very strongly or strongly acid.
The C horizon has hue of 5Y through 7.5YR. It ranges from very strongly acid to medium acid.
COMPETING SERIES: These are the Arrow, Darling, Holroyd, and Nambe series. Arrow soils have a lithic contact at depths of 20 to 40 inches. 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 a spodic horizon.
GEOGRAPHIC SETTING: Pinkham soils are on moderately to steeply sloping alluvial fans, glacial moraines, till plains, and mountain side slopes. Slopes typically range from 4 percent to about 60 percent or more. These soils formed in thick, noncalcareous, alluvial fan materials derived from gneiss, schist, and quartzite. At the type location the average annual precipitation is 18 inches with peak periods of precipitation in the spring and early summer months. Mean annual temperature is 30 degrees F., and mean summer temperature is 42 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Darling soils and the MacFarlane soils. MacFarlane soils have argillic horizons.
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: Mountain areas of Colorado. The series is of moderate extent.
MLRA OFFICE RESPONSIBLE: Lakewood, Colorado
SERIES ESTABLISHED: Jackson County, Colorado, 1973.
REMARKS: Last updated by the state 11/73.