LOCATION GRANDMESA COEstablished Series
TAXONOMIC CLASS: Clayey-skeletal, smectitic Abruptic Argicryolls
TYPICAL PEDON: Grandmesa loam - Engelmann spruce-subalpine fir woodland. (Colors are for dry soil unless otherwise noted.)
Oe--0 to 1 inch; partially decomposed leaves, grass, and twigs.
A1--1 to 10 inches; dark grayish brown (10YR 4/2) loam, very dark grayish brown (10YR 3/2) moist; moderate fine granular structure; slightly hard, very friable, slightly sticky and slightly plastic; neutral (pH 6.6); clear smooth boundary.
A2--10 to 14 inches; brown (10YR 5/3) cobbly loam, dark brown (10YR 4/3) moist; weak fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; 5 percent pebbles, 20 percent cobbles; slightly acid (pH 6.4); clear smooth boundary. (Combined thickness of A is 10 to 15 inches.)
E--14 to 19 inches; pinkish gray (7.5YR 7/2) very cobbly loam, brown
(7.5YR 4/2) moist; weak medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; few pebbles, 40 percent cobbles; slightly acid (pH 6.2); abrupt smooth boundary. (4 to 8 inches thick)
Bt--19 to 33 inches; reddish brown (5YR 5/4) very cobbly clay, dark reddish brown (5YR 3/4) moist; strong medium angular blocky structure; very hard, very firm, very sticky and very plastic; many prominent clay films on ped faces; 10 percent pebbles, 50 percent cobbles; slightly acid (pH 6.2); abrupt smooth boundary. (12 to 16 inches thick)
2R--33 inches; basalt bedrock.
TYPE LOCATION: Mesa County, Colorado; near Crater View in the NE1/4 NE1/4 of Sec. 5, T. 12 S., R. 96 W. Latitude: 39 degrees, 2 minutes, 21 seconds N.; Longitude: 108 degrees, 8 minutes, 21 seconds W.
RANGE IN CHARACTERISTICS: Mean annual soil temperature ranges from 34 to 37 degrees F. Mean summer soil temperature ranges from 42 to 45 degrees F. Bedrock is at a depth of 20 to 40 inches. The mollic epipedon is 10 to 15 inches thick. The particle-size control section has 35 to 75 percent rock fragments. Reaction is slightly acid or neutral. The moisture control section is usually moist when the soil temperature at 20 inches is greater than 41 degrees F.
The A horizon has hue of 10YR or 7.5YR, value of 4 or 5 dry, 2 or 3 moist, with 4 value in the lower parts and chroma of 2 or 3.
The E horizon has hue of 10YR or 7.5YR, value of 6 or 7 dry, 4 or 5 moist and chroma of 1 or 2.
The Bt horizon has hue of 7.5YR or 5YR, value of 5 or 6 dry, 3 through 5
moist and chroma of 2 through 4.
COMPETING SERIES: These are the Callings (UT), and Sunshine (CO) series. Callings soils have stones dominant in the particle-size control section and have a fragmental substratum above 40 inches.
GEOGRAPHIC SETTING: Grandmesa soils are on mesa tops. Slopes range from 0 to 10 percent. The soils formed in glacial till derived from basalt. Mean annual temperature ranges from 32 to 35 degrees F., and mean annual precipitation ranges from 30 to 40 inches. Elevation ranges
from 9,900 to 10,700 feet. The frost-free period is 15 to 50 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the proposed Elkwalow and Doughspon soils. Elkwalow soils are somewhat poorly or moderately well drained with bedrock between 40 to 60 inches. Doughspon soils lack a diagnostic albic horizon and are more than 40 inches to bedrock.
DRAINAGE AND PERMEABILITY: Well drained; slow to medium runoff; slow permeability.
USE AND VEGETATION: This soil is used for timber production, firewood, wildlife habitat, and recreation. Dominant trees include Engelmann spruce and subalpine fir.
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: Diagnostic features include a mollic epipedon, the zone from 0
to 10 inches, an albic horizon, the zone from 14 to 19 inches and an argillic horizon, the zone from 19 to 33 inches. Last updated by the state 4/93. This revision documents a change in class from mixed to montmorillonitic mineralogy based on NSSL data.