LOCATION MILLSWITCH COEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive Ustic Calcicryepts
TYPICAL PEDON: Millswitch gravelly loam, on a southwest facing 30 percent mountain slope under Rocky Mountain Douglas fir at an elevation of 9,480 feet. (colors are for dry soil unless otherwise noted)
Oi--0 to 1 inch; mat of slightly decomposed needles, twigs, and leaves (0 to 2 inches thick)
A--1 to 3 inches; light brownish gray (10YR 6/2) gravelly loam, very dark grayish brown (10YR 3/2) moist; moderate medium subangular blocky structure; soft, friable, slightly sticky and slightly plastic; 15 percent gravel; slightly alkaline (pH 7.6); clear smooth boundary. (1 to 4 inches thick)
Bw--3 to 13 inches; pale brown (10YR 6/3) very gravelly loam, dark brown (10YR 3/3) moist; moderate medium subangular blocky structure; soft, friable, slightly sticky and slightly plastic; 30 percent gravel, 5 percent cobbles; slightly effervescent; slightly alkaline (pH 7.6); clear wavy boundary. (6 to 14 inches thick)
Bk1--13 to 25 inches; very pale brown (10YR 7/4) extremely cobbly very fine sandy loam, yellowish brown (10YR 5/4) moist; moderate medium subangular blocky structure; slightly hard, friable, nonsticky and slightly plastic; 35 percent gravel, 30 percent cobbles; calcium carbonates disseminated and segregated into few fine seams and as coats on rock fragments; strongly effervescent; moderately alkaline (pH 8.2); clear wavy boundary.
Bk2--25 to 31 inches; very pale brown (10YR 7/4) extremely cobbly sandy loam, yellowish brown (10YR 5/4) moist; weak fine subangular blocky structure; soft, very friable, nonsticky and nonplastic; 35 percent gravel, 25 percent cobbles; calcium carbonates disseminated and segregated into few fine seams and as coats on rock fragments; strongly effervescent; moderately alkaline (pH 8.4); clear wavy boundary.
Bk3--31 to 43 inches; very pale brown (10YR 8/4) cobbly loam, very pale brown (10YR 7/4) moist; massive; soft, very friable, nonsticky and slightly plastic; 10 percent gravel, 20 percent cobbles; calcium carbonates disseminated and segregated into few fine seams and as coats on rock fragments; strongly effervescent; moderately alkaline (pH 8.4); clear wavy boundary.
Bk4--43 to 55 inches; very pale brown (10YR 8/4) loam, very pale brown (10YR 7/4) moist; massive; soft, very friable, nonsticky and nonplastic; 5 percent gravel, 2 percent cobbles; calcium carbonates disseminated and as coats on rock fragments; strongly effervescent; moderately alkaline (pH 8.0); clear wavy boundary. (combined thickness of the Bk horizon is 22 to 53 inches)
Cr--55 inches; weathered limestone bedrock.
TYPE LOCATION: Saguache County, Colorado; about 4 miles east of Sargents, Colorado; within an unsectionized area of Gunnison National Forest, estimated to be in Section 19, T. 48 N., R. 6 E.; USGS Pahlone Peak topographic quadrangle; latitude 38 degrees, 23 minutes, 43 seconds north and longitude 106 degrees, 20 minutes, 47 seconds west, NAD 1927.
RANGE IN CHARACTERISTICS: Depths in this section are measured from the top of the mineral soil surface.
Soil moisture: The soil moisture control section (smcs) is affected by precipitation that falls evenly throughout the year with the exception of a significant increase in July and August. The smcs is driest during the fall. The smcs is too dry for Udic and is considered to have an Ustic soil moisture regime.
Mean annual soil temperature: 37 to 45 degrees F.
Particle-size control section: 10 to 18 percent clay, 35 to 75 percent rock fragments
Depth to paralithic contact: 40 to 60 inches to limestone or dolomite
Thickness of ochric epipedon: 1 to 4 inches.
Depth to cambic horizon: 1 to 4 inches.
Depth to calcic horizon: 10 to 20 inches
A horizon:
Hue: 7.5YR or 10YR
Value: 5 or 6 dry, 3 or 4 moist
Chroma: 2 or 3 dry or moist
Reaction: slightly alkaline (pH 7.4 to pH 7.8)
Rock fragments: limestone or dolomite. 10 to 25 percent total rock fragments; 10 to 25 percent gravel, 0 to 5 percent cobbles.
Calcium carbonate equivalent: 0 to 5 percent.
Bw horizon:
Hue: 7.5YR or 10YR
Value: 6 or 7 dry, 3 to 5 moist
Chroma: 3 or 4 dry or moist
Texture: very gravelly loam, very gravelly sandy loam
Reaction: slightly alkaline (pH 7.4 to pH 7.8)
Rock fragments: limestone or dolomite. 35 to 50 percent total rock fragments; 25 to 50 percent gravel, 0 to 15 percent cobbles.
Calcium carbonate equivalent: 0 to 5 percent.
Bk1 and Bk2 horizons:
Hue: 7.5YR or 10YR
Value: 7 or 8 dry, 5 to 7 moist
Chroma: 3 to 5 dry or moist
Texture: extremely cobbly very fine sandy loam, extremely cobbly sandy loam
Reaction: moderately alkaline (pH 7.9 to pH 8.4)
Rock fragments: limestone or dolomite. 35 to 70 percent total rock fragments; 25 to 40 percent gravel, 20 to 40 percent cobbles.
Calcium carbonate equivalent: 20 to 35 percent.
Bk3 and Bk4 horizons:
Hue: 7.5YR or 10YR
Value: 7 or 8 dry, 5 to 7 moist
Chroma: 3 to 5 dry or moist
Texture: cobbly loam, loam, very cobbly loam, very cobbly sandy loam, extremely cobbly loam, extremely cobbly sandy loam
Reaction: moderately alkaline (pH 8.4) to strongly alkaline (pH 9.0)
Rock fragments: limestone or dolomite. 5 to 70 percent total rock fragments; 5 to 40 percent gravel, 0 to 40 percent cobbles.
Calcium carbonate equivalent: 30 to 55 percent.
COMPETING SERIES: These are the
Danavore,
Ellena,
Elve,
Hiore,
Pergrin,
Rubick,
Scout,
Shadow,
Taglake, and
Vandamore.
Danavore, Ellena, Elve, Hiore, Pergrin, Rubick, Scout, Shadow, Taglake, Vandamore: lack calcic horizons
GEOGRAPHIC SETTING:
Parent material: colluvium over residuum from limestone or dolomite
Landform: mountain slopes
Slopes: 25 to 65 percent
Elevation: 9,200 to 11,400 feet
Mean annual temperature: 32 to 40 degrees F.
Mean annual precipitation: 18 to 26 inches
Frost-free period: 45 to 65 days
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Herbman and Seitz soils. Herbman soils are on backslopes and shoulders and are less than 20 inches to paralithic contact. Seitz soils are on backslopes and toeslopes and have more than 35 percent clay in the particle-size control section.
DRAINAGE AND PERMEABILITY: well drained; very high runoff; moderate permeability.
USE AND VEGETATION: This soil is used for wood products. Potential native vegetation is Rocky Mountain Douglas fir with an understory of elk sedge, common juniper, kinnikinnick, and myrtle whortleberry. It is in the Rocky Mountain Douglas Fir Woodland Site, Forest Cover Type 210.
DISTRIBUTION AND EXTENT: Western Colorado in LRR E and MLRA 48A. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Cochetopa Soil Survey Area, Gunnison National Forest, Saguache County, Colorado, 1996. The name comes from Millswitch Creek.
REMARKS: Diagnostic horizons and features recognized in this pedon.
Particle-size control section: the zone from 10 to 40 inches. (Bw, Bk1, Bk2, Bk3 horizons)
Ochric epipedon: the zone from 0 to 2 inches. (A horizon)
Cambic horizon: the zone from 2 to 30 inches. (Bw, Bk1 and Bk2 horizons)
Calcic horizon: the zone from 13 to 55 inches. (Bk horizons)
Paralithic contact: the contact weathered limestone bedrock at 55 inches. (Cr layer)
Taxonomic version: Tenth Edition, 2006.
The 01/2008 revision changes the subgroup classification from Ustic Eutrocryepts to Ustic Calcicryepts.