LOCATION MAMMOTH COEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, micaceous Lamellic Dystrocryepts
TYPICAL PEDON: Mammoth very gravelly sandy loam, woodland. (Colors are for dry soil unless otherwise noted.)
Oi--0 to 1 inch; slightly decomposed needles, moss, twigs and cones.
E--1 to 10 inches; pale brown (10YR 6/3) very gravelly sandy loam, dark yellowish brown (10YR 4/4) moist; weak very fine subangular blocky structure parting to weak medium granular; soft, very friable, nonsticky and nonplastic; common visible mica flakes as fine and very fine sand sized particles; 30 percent gravel, 5 percent cobbles, 5 percent stones; moderately acid; clear wavy boundary.
E&Bt1--10 to 16 inches; yellowish brown (10YR 5/4) gravelly loam, dark yellowish brown (10YR 4/4) moist; weak medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; 1 discontinuous lamellae 1/2 centimeter thick, sandy clay loam, brown (7.5YR 4/4); common visible mica flakes as fine and very fine sand sized particles; 30 percent gravel and 2 percent cobbles; moderately acid; gradual smooth boundary.
E&Bt2--16 to 22 inches; yellowish brown (10YR 5/4) very gravelly loamy sand, brown (7.5YR 5/4) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; 1 continuous wavy lamellae 1/2 centimeter thick, sandy clay loam, brown (7.5YR 4/4); common visible mica flakes as fine and very fine sand sized particles; 40 percent gravel and 2 percent cobbles; moderately acid; gradual smooth boundary.
E&Bt3--22 to 32 inches; yellowish brown (10YR 5/4) very gravelly sandy loam, strong brown (7.5YR 4/6) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; 2 continuous wavy lamellae 1 centimeter thick, clay coatings on fine and medium sand, sandy clay loam, strong brown (7.5YR 4/6); common visible mica flakes as fine and very fine sand sized particles; 40 percent gravel and 5 percent cobbles; moderately acid; gradual smooth boundary.
E&Bt4--32 to 59 inches; strong brown (7.5YR 5/6) very gravelly loamy sand, strong brown (7.5YR 4/6) moist; weak fine subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; 3 continuous and discontinious lamellae, 1 centimeter thick, sandy clay loam, strong brown (7.5YR 5/6); many visible mica flakes as fine and very fine sand sized particles; 30 percent gravel and 10 percent cobbles; slightly acid; gradual wavy boundary.
C--59 to 67 inches; strong brown (7.5YR 4/6) stony loamy coarse sand, brown (7.5YR 4/4) moist, weak medium subangular blocky structure; soft, very friable, nonsticky and nonplastic; many visible mica flakes as fine and very fine sand sized particles; 10 percent cobbles, 20 percent stones; moderately acid.
TYPE LOCATION: Clear Creek County, Colorado; about 1800 feet north and 250 feet east of the southwest corner of sec. 20, T.4 S., R. 72 W. (Latitude 39 degrees, 40 minutes, 54 seconds north, Longitude 105 degrees, 28 minutes, 4 seconds West).
RANGE IN CHARACTERISTICS:
Soil moisture: The soil moisture control section is udic bordering on ustic.
Mean annual soil temperature: 37 to 42 degrees F
Mean summer soil temperature: 46 to 55 degrees F
Particle-size control section (weighted average):
Clay content: 10 to 27 percent
Sand content: 45 to 66 percent
Rock fragments: 35 to 75 percent
Base saturation: 25 to 60 percent
A or E horizon:
Hue: 7.5YR through 10YR
Value: 4 through 7 dry, 2 through 6 moist
Chroma: 1 through 4
Texture: loamy sand, sandy loam, coarse sandy loam modified by rock fragments
Reaction: strongly acid to slightly acid
E&Bt horizon(s):
Hue: 7.5YR through 10YR
Value: 4 through 6 dry, 3 through 5 moist
Chroma: 2 through 4
Texture: loamy sand, sandy loam, and loam modified by rock fragments
Silicate clays and cutans exist in the lamellae occurring both as continuous and discontinuous. These lamellae do not total 15 cm. (6 inches) or more to be designated as an argillic subsoil.
Reaction: strongly acid to slightly acid
C horizon (when present):
Hue: 5YR through 7.5YR
Texture: loamy coarse sand, coarse sandy loam, and sandy loam modified by rock fragments
Reaction: very strongly acid through moderately acid
COMPETING SERIES: This is the Ohman series. The Ohman soil is moderately deep to paralithic rock.
GEOGRAPHIC SETTING: Mammoth soils are on mountain slopes and ridges. Slopes are 9 to 75 percent. The soils formed in colluvium and slope alluvium from mixed igneous and metamorphic rocks. Elevation is 7,400 to 10,500 feet. Mean annual precipitation is 20 to 24 inches. Mean annual temperature is 37 to 42 degrees. The average frost-free season is 25 to 70 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bendemeere, Ohman, Legault, Hiwan, and Ivywild soils. Bendemeere do not have paralithic contact within 40 inches and contain enough lamellae thickness to be an argillic. Ohman soils are moderately deep to paralithic bedrock. Legault soils have a paralithic contact above 20 inches. Hiwan soils have a lithic contact above 20 inches. Ivywild soils lack continuous lamellae in the cambic.
DRAINAGE AND PERMEABILITY: Well to somewhat excessively drained; moderate to rapid runoff; rapid permeability.
USE AND VEGETATION: These soils are used for recreation, woodland, wildlife habitat, and scattered homesite development. Native vegetation is lodgepole pine, Engelmann's spruce, subalpine fir, few scattered quaking aspen, Rocky Mountain Douglas-fir, and grouse whortleberry.
DISTRIBUTION AND EXTENT: Occurs in the central mountains of Colorado. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: MO6, Bozeman, Montana
SERIES ESTABLISHED: Clear Creek County, Georgetown Soil Survey Area, Colorado, 2000.
REMARKS: Diagnostic features include lamellae at depths of 7 to 59 inches. Series name is from a lake and creek in northern Gilpin County, Colorado.
In the subsoil the quantity of lamellae does not total 6 inches (15 cm.) to the 2 meter depth.
Taxonomic Version: Eighth Edition, 1998
The mineralogy class was changed from paramicaceous to micaceous in 07/2010 by the National Soil Survey Center on request of the responsible MLRA regional office. The change was necessary based on the eleventh edition of the Keys to Soil Taxonomy, 2010.