LOCATION PACKTRAIL COEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive Typic Humicryepts
TYPICAL PEDON: Packtrail loam-alpine grass park. (Colors are for dry soils unless otherwise noted.)
A--0 to 10 inches; brown (10YR 4/3) loam, dark brown (10YR 3/3) moist; moderate fine granular structure; soft, very friable, slightly sticky and slightly plastic; 10 percent pebbles; medium acid; clear smooth boundary. (6 to 14 inches thick)
Bw--10 to 24 inches; brown (10YR 5/3) loam, dark brown (10YR 3/3) moist; weak medium subangular blocky structure parting to weak fine granular; slightly hard, friable, slightly sticky and slightly plastic; 10 percent pebbles; medium acid; clear wavy boundary. (8 to 18 inches thick)
C--24 to 29 inches; brown (10YR 5/3) extremely cobbly loam, dark yellowish brown (10YR 3/4) moist; massive; slightly hard, friable, slightly sticky and slightly plastic; 10 percent pebbles, 75 percent cobble; medium acid. (4 to 10 inches thick)
R--29 inches; fractured basalt.
TYPE LOCATION: Garfield County, Colorado; approximately 1,900 feet west and 850 feet south of the northeast corner of Sec. 29, T. 1 N., R. 87 W. (area is not sectionized at this time, legal location is estimated). U.S.G.S. Devils Causeway quad.; lat. 40 degrees, 1 minute, 48 seconds N., and long. 107 degrees, 10 minutes, 41 seconds W.
RANGE IN CHARACTERISTICS: The mean annual soil temperature ranges from 34 to 38 degrees F. Mean summer soil temperature ranges from 40 to 50 degrees F. Typically these soils are noncalcareous throughout. Depth to the basalt bedrock ranges from 20 to 40 inches. The particle-size control section has 18 to 27 percent clay, 25 to 50 percent silt and 30 to 60 percent sand. Rock fragments on a weighted basis in the particle-size control section range from 10 to 35 percent, are 1/8 to 3 inches in diameter and increase with depth. The soil ranges from slightly acid through strongly acid.
The A horizon has hue of 2.5Y through 7.5YR, value of 4 or 5, 2 or 3 moist, and chroma of 1 through 3.
The Bw horizon has color and texture similar to the A horizon.
The C horizon has hue of 2.5Y through 7.5YR, value of 4 through 6, 2 through 4 moist and chroma of 2 through 4.
COMPETING SERIES: These are the Archabal (ID) and Domo (CO) soils. Archabal soils lack bedrock above depths of 40 inches and are developed on acid igneous rocks and minor amounts of basic igneous rocks. In addition, they have a thicker solum. The Domo soils lack hard bedrock above a depth of 40 inches.
GEOGRAPHIC SETTING: Packtrail soils are on high plateaus and flat mountaintops at elevations of 10,900 to 11,400 feet. Slopes range from 3 to 30 percent. These soils formed in residuum and alluvium of basaltic materials. Mean annual precipitation is 28 to 35 inches the majority of which comes as snow. Mean annual temperature is 34 to 38 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Angostura, Grenadier, and the Domo and Causewa soils. Angostura and Grenadier are forested, have ochric epipedons and Angostura soils have argillic horizons. Causewa soils have loamy-skeletal particle-size control sections and Domo soils have bedrock at depths greater than 40 inches.
DRAINAGE AND PERMEABILITY: Well drained; slow runoff; moderately rapid permeability.
USE AND VEGETATION: Packtrail soils are used for wildlife habitat, recreation and some sheep grazing. Native vegetation includes redtop yarrow, rushes, sedges, scattered willow and other alpine grasses and forbs.
DISTRIBUTION AND EXTENT: Mountainous areas of western Colorado. This series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Flat Tops Soil Survey Area; Garfield County, Colorado; 1984.
REMARKS: Diagnostic features include an umbric epipedon from 0 to 24 inches; a cambic horizon from 10 to 24 inches; and a lithic contact at 29 inches. Last updated by the state 4/94.