LOCATION BULLBASIN COTentative Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive Pachic Haplocryolls
TYPICAL PEDON: Bullbasin loam - rangeland. (Colors are for dry soil unless otherwise noted.)
A1--0 to 1 inch; dark grayish brown (10YR 4/2) loam, very dark grayish brown (10YR 3/2) moist; weak fine subangular blocky structure parting to weak fine granular ; slightly hard, friable, nonsticky and nonplastic; neutral (pH 6.8); clear smooth boundary.
A2--1 to 7 inches; dark grayish brown (10YR 4/2) loam, very dark grayish brown (10YR 3/2) moist; moderate medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; 5 percent pebbles; slightly acid (pH 6.4); gradual smooth boundary.
A3--7 to 25 inches; dark grayish brown (10YR 4/2) loam, very dark grayish brown (10YR 3/2) moist; weak medium subangular blocky structure; slightly hard, friable, nonsticky and nonplastic; 10 percent pebbles; slightly acid (pH 6.4); clear smooth boundary. (combined thickness of A horizons is 20 to 32 inches)
Bw--25 to 34 inches; light yellowish brown (10YR 6/4) loam, dark yellowish brown (10YR 4/4) moist; weak fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and nonplastic; 5 percent pebbles; slightly acid (pH 6.2); gradual smooth boundary. (8 to 12 inches thick)
2BC--34 to 47 inches; light yellowish brown (10YR 6/4) very cobbly loam, dark yellowish brown (10YR 4/4) moist; massive; slightly hard, friable, slightly sticky and nonplastic; 10 percent pebbles, 50 percent cobbles; slightly acid (pH 6.4); abrupt smooth boundary. (12 to 14 inches thick)
3R--47 inches; basalt bedrock.
TYPE LOCATION: Mesa County, Colorado; NW1/4 of the NE1/4 of Sec. 16, T. 12 S., R. 96 W. Latitude: 39 degrees, 00 minutes, 54 seconds N.; Longitude: 108 degrees, 07 minutes, 20 seconds W.
RANGE IN CHARACTERISTICS: Mean annual soil temperature ranges from 35 to 37 degrees F. Average summer soil temperature is 44 to 47 degrees. The soil moisture control section is usually moist. Bedrock is at a depth of 40 to 60 inches. The particle-size control section contains 5 to 25 percent rock fragments and 10 to 27 percent clay. They are typically gravel, but include cobble. Reaction is neutral to slightly acid throughout the pedon. Mollic epipedon ranges from 16 to 40 inches thick.
The A horizon has hue of 10YR or 7.5YR, value of 4 or 5 dry, 2 or 3 moist, with chroma of 1 or 2.
The Bw horizon has hue of 10YR or 7.5YR, value of 5 or 6 dry, 4 or 5 moist, with chroma of 3 through 6. Textures are loam or sandy loam.
The BC or C horizon has hue of 10YR or 7.5YR, value of 5 or 6 dry, 4 or 5 moist, with chroma of 3 or 4. Textures are loam or sandy loam.
COMPETING SERIES: These are the
Adel (MT),
Bullrey (ID),
Duff (NV),
Gallatin (MT),
Hackwood (NV), Idmon (T)(ID),
Karlan (ID),
Lamphier (CO),
Leavittville (WY),
Lespate (CO),
Mundos (WY), Osmund (WY),
Pavohroo (ID),
Rhone (CO),
Secondset (CO),
Strickland (NV),
Taterheap (T)(CO),and
Winevada (NV) soils.
The Adel, Bullrey, Lamphier, and Rhone soils do not have moisture control sections that are usually moist. In addition, the Adel soils lack a 2BC horizon with 50 percent cobbles above 40 inches. The Duff, Hackwood, Pavohroo, and Taterheap soils have mean annual soil temperatures warmer than 38 degrees F. The Gallatin, Leavittville,Mundos, and Osmund soils have consistent k horizons. The Idmon soils are underlain by sand and gravel below a depth of about 30 inches, are moderately well drained and have mean annual soil temperature of 39 to 41 degrees F. The Karlan, Lespate, Secondset, Strickland, and Winevada soils have bedrock between 20 and 40 inches. Gallatin soils lack a 2BC horizon with 50 percent cobble above 40 inches.
GEOGRAPHIC SETTING: Bullbasin soils are on mesa tops and side slopes. Slopes range from 0 to 30 percent. The soils formed in glacial till derived from basalt, andesite, or rhyolite. Mean annual temperature ranges from 32 to 36 degrees F., and mean annual precipitation ranges from 30 to 40 inches. Elevation ranges from 9,400 to 10,700 feet. The frost-free period is 50 to 60 days.
GEOGRAPHICALLY ASSOCIATED SOILS: This is the Doughspon soil. Doughspon soils have pachic epipedons and are fine-textured.
DRAINAGE AND PERMEABILITY: Well or moderately well drained; slow to medium runoff; moderate permeability.
USE AND VEGETATION: This soil is used for livestock grazing, wildlife habitat, and recreation. In Colorado it is in the Wet Subalpine loam range site, with vegetation of red fescue, elk sedge, and alpine timothy.
DISTRIBUTION AND EXTENT: West central Colorado. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES PROPOSED: Mesa County (Grand Mesa-West Elk Soil Survey Area), Colorado, 1988.
REMARKS: This soil is named after Bull Basin in the Grand Mesa National Forest. Diagnostic features include a mollic (pachic) epipedon; the zone from 0 to 25 inches and a cambic horizon, the zone from 25 to 34 inches. Last updated by the state 4/93.