LOCATION MIRROR CO+WYEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, isotic Typic Humicryepts
TYPICAL PEDON: Mirror silt loam - native grassland. (Colors are for dry soil unless otherwise noted.)
Oi and Oe--0 to 1 inch; undecomposed and partially decomposed organic matter, chiefly alpine grasses and plant roots.
A--1 to 9 inches; very dark gray (10YR 3/1) gravelly sandy loam, black (10YR 2/1) moist; moderate fine granular structure; soft, very friable, slightly sticky and slightly plastic; 20 percent angular gravel; strongly acid (pH 5.2); clear smooth boundary. (5 to 15 inches thick)
Bw1--9 to 13 inches; brown (7.5YR 5/3) gravelly sandy loam, brown (7.5YR 4/3) moist; weak fine subangular blocky structure parting to fine granular; slightly hard, very friable, nonsticky and nonplastic; 25 percent angular gravel; small pellets of humus and iron throughout the horizon; very strongly acid (pH 5.0); clear wavy boundary. (4 to 8 inches thick)
Bw2--13 to 23 inches; reddish yellow (7.5YR 6/6) very gravelly sandy loam, strong brown (7.5YR 5/6) moist; weak fine subangular blocky structure parting to fine granular; slightly hard, very friable, nonsticky and nonplastic; 60 percent gravel; numerous dark pellets of humus and iron throughout the horizon; very strongly acid (pH 4.8); gradual wavy boundary. (6 to 17 inches thick)
C--23 to 31 inches; light yellowish brown (10YR 6/4) extremely stony sandy loam, yellowish brown (10YR 5/4) moist; massive; slightly hard, very friable, nonsticky and nonplastic; 75 percent stones; very strongly acid (pH 4.8); abrupt wavy boundary. (0 to 25 inch thick)
R--31 inches; quartz monzonite.
TYPE LOCATION: Gunnison County, Colorado; above timberline near the crest of the Cumberland Pass in an excavation to the southwest of the highway in Sec. 12, T. 51 N., R. 4 E.
RANGE IN CHARACTERISTICS:
Mean annual soil temperature: about 32 degrees F. to 36 degrees F.
Mean summer soil temperature: about 40 degrees F. to 47 degrees F.
Thickness of the umbric epipedon: ranges from 7 to 15 inches.
Thickness of the cambic horizon: ranges from 10 to 40 inches.
Depth to lithic contact: 20 to 40 inches.
This soil does not have permafrost.
Particle-size control section (weighted average):
Percent clay: 5 to 18 percent
Percent silt: 5 to 45 percent
Percent sand: 40 to 82 percent with more than 35 percent fine or coarser sand.
Percent rock fragments: 35 to 75 percent particle-size control section and are usually cobbles and gravel but range to stones in some pedons.
A horizon:
Hue: 2.5Y through 7.5YR
Value: 2 through 5 dry, 1 through 3 moist
Chroma: neutral through 3
Texture: sandy loam and loam
Rock fragments: 20 to 75 percent total rock fragments (gravelly and extremely cobbly modifiers allowed)
Reaction: strongly acid to very strongly acid
Base saturation: less than 50 percent
Organic carbon: 1 to 15 percent and decreases uniformly below the umbric epipedon.
Bw horizon:
Hue: 2.5Y through 5YR
Value: 4 through 7 dry, 3 through 5 moist
Chroma: 3 through 6
Texture: sandy loam and loam
Rock fragments: 35 to 70 percent total rock fragments (gravelly, extremely cobbly, and extremely modifiers allowed)
Reaction: strongly acid to very strongly acid
Base saturation: 30 to 50 percent
C horizon: (when present)
Hue: 2.5Y through 7.5YR
Value: 6 or 7 dry, 4 or 5 moist
Chroma: 2 through 4
Texture: sandy loam
Rock fragments: 61 to 75 percent total rock fragments (extremely stony modifier allowed)
Reaction: strongly acid to very strongly acid
Base saturation: 30 to 50 percent
COMPETING SERIES:
These are the
Bigelow,
Bross, Causew,
Crannler,
Henline,
Hossick,
Meredith, and
Penitente series.
Causewa soils: have 18 to 27 percent clay in the particle-size control section.
Bigelow, Bross, and Penitente soils lack lithic contact above a depth of 40 inches.
Crannler and Henline soils: do not have cambic horizons.
Causewa and Henline soils: have basaltic rock fragments.
Hossick soils: have andesite or latite rock fragments.
Meredith soils: have fragmental materials at depths of 20 to 40 inches.
GEOGRAPHIC SETTING:
Landform: mountains and mountain slopes
Position: crests and alpine ridges above timberline
Slopes: 1 to 60 percent
Parent material: colluvium derived from monzonite and similar bedrock materials.
The average annual precipitation: 35 to 50 inches which is mainly in the form of snow
Mean annual temperature: 32 to 36 degrees F.
Elevation: ranges from 11,400 to 13,700 feet.
Frost-free season: 10 to 20 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Haverly and Ptarmigan soils. Haverly and Ptarmigan soils do not have skeletal particle-size control sections.
DRAINAGE AND PERMEABILITY: Well drained; low runoff; moderately rapid permeability.
USE AND VEGETATION: These soils are used principally for pastureland and for recreational purposes. Native vegetation consists of moss, arenaria, sheep fescue, sedges, geum, alpine willow, Scribner wheatgrass, and sedum.
DISTRIBUTION AND EXTENT: High mountainous areas of central Colorado and adjacent parts of Wyoming. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Jackson County, Colorado; 1973.
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Umbric epipedon: the zone from 1 to 9 inches (A horizon)
Lithic contact: monzonite bedrock at 31 inches (R horizon)
Cambic horizon: the zone from 9 to 23 inches (Bw1, Bw2)
The classification in 1987 was loamy-skeletal, mixed Pergelic Cryumbrepts. The classification in 1966 was loamy-skeletal, mixed, Typic Cryorthods
The revision of May 2007 updated the taxonomic class from Humic Dystrocryepts is based on the tenth edition of the Keys to Soil Taxonomy, 2006.
The type location needs to be moved to a location that has the type location in a published manuscript. With the base of the cambic at 23 inches the epipedon meets the thickness criterion for an umbric. However, the layer designated as a C horizon seems to meet the criteria for a cambic. If so, then the umbric epipedon is too thin. A more representative pedon was not available to better reflect the umbric epipedon thickness.