LOCATION HOURGLASS COEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive Typic Argicryolls
TYPICAL PEDON: Hourglass loam. (Colors are for dry soil unless otherwise noted.)
A--0 to 11 inches; dark grayish brown (10YR 4/2) loam, very dark grayish brown (10YR 3/2) moist; moderate fine granular structure; soft, very friable; nonsticky and nonplastic; 10 percent gravel, 1 percent cobble, 1 percent stones; slightly acid (pH 6.2); clear wavy boundary. (7 to 16 inches thick)
Bt1--11 to 18 inches; brown (7.5YR 5/4) clay loam, brown (7.5YR 4/3) moist; weak, medium subangular blocky structure parting to moderate, medium granular; hard, firm, moderately sticky and plastic: few faint clay films on faces of peds; 10 percent gravel, 2 percent cobble, 1 percent stones; neutral (pH 6.6); clear wavy boundary.
Bt2--18 to 31 inches; brown (7.5YR 4/4) gravelly clay loam, brown (7.5YR 4/4) moist; moderate, medium subangular blocky structure; hard, firm, moderately sticky and moderately plastic; few distinct clay films on faces of peds; 10 percent gravel, 5 percent cobble, 3 percent stones; neutral (pH 6.6); clear wavy boundary.
Bt3--31 to 46 inches; brown (7.5YR 4/3), very stony clay loam, reddish brown (5YR 4/3) moist; moderate, medium angular blocky structure that parts to moderate, medium subangular blocky; hard, firm, moderately sticky and moderately plastic; few distinct clay films on faces of peds; 5 percent gravel, 10 percent cobble, 20 percent stones; neutral (pH 6.8); clear wavy boundary. (combined thickness of the Bt horizons is 30 to 40 inches)
C--46 to 60 inches; brown (7.5YR 5/2) very stony clay loam, brown (7.5YR 4/2) moist; massive; hard, friable, moderately sticky and moderately plastic; 15 percent gravel, 10 percent cobble, 20 percent stone; neutral (pH 7.0).
TYPE LOCATION: La Plata County Colorado, northeast of Durango on Missionary Ridge; in the southeast quarter of the southeast quarter of sec. 3, T. 37 N., R. 8 W.
RANGE IN CHARACTERISTICS:
Soil Moisture regime: udic; dry in some part of the moisture control section for less than 45 cumulative days (typic udic subclass).
Mean annual soil temperature: 34 to 40 degrees F.
Mean summer soil temperature: 50 to 56 degrees F.
Thickness of the mollic epipedon and depth to the argillic horizon: 7 to 16 inches
Particle-size control section (weighted averages):
Clay content: 20 to 35 percent
Rock fragment content: 15 to 35 percent
A horizon:
Hue: 7.5YR or 10YR
Value: 4 or 5 dry, 2 or 3 moist
Chroma: 1 to 3, dry or moist
Reaction: slightly acid or neutral
Bt horizon:
Hue: 5YR to 10YR
Value: 4 or 5 dry, 3 or 4 moist
Chroma: 3 to 6, dry or moist
Texture (fine earth fraction): clay loam or sandy clay loam
Clay content: 20 to 35 percent
Rock fragment content: 5 to 35 percent, dominantly sandstone and limestone
Reaction: slightly acid or neutral
C horizon:
Hue: 5YR to 10YR
Value: 5 or 6 dry, 4 or 5 moist
Chroma: 2 to 6, dry or moist
Texture (fine earth fraction): loam or clay loam
Rock fragment content: 5 to 45 percent, dominantly sandstone and limestone
Reaction: slightly acid to neutral
COMPETING SERIES: These are the
Mult,
Sponsor, and
Wildcow series.
In addition, the following series may be competitors when their classification is updated:
Buffork,
Cific,
Dra,
Gebson,
Lyonman,
Michelson,
Monida,
Newlands,
Passcreek,
Primeaux,
Rammel,
Shotgun,
Swede,
Tripit, and
Zade series.
Buffork, Cific, Tripit, and Zade soils: have a paralithic contact.
Dra, Mult, Newlands, Passcreek, Primeaux, Rammel, Shotgun, soils: have a lithic contact.
Gebson, Michelson, and Monida soils have a horizon of secondary calcium carbonate accumulation.
Lyonman soils: have a xeric moisture regime.
Sponsor soils: have hue of 2.5YR or 5YR in the Bt horizon and have rock fragments of gneiss, schist, and granite.
Swede soils: have less than 15 percent (weighted average) rock fragments in the particle-size control section.
Wildcow soils: are slightly alkaline.
GEOGRAPHIC SETTING:
Parent material: slope alluvium and colluvium dominantly from sandstone and shale, but also from mixed sources.
Landform: backslopes, footslopes, and toeslopes of mountains at elevations of 8,000 to 11,500 feet.
Slopes: 5 to 60 percent.
Mean annual temperature: 32 to 38 degrees F.
Average annual precipitation: 30 to 40 inches.
Wettest months: July and August.
Driest months: May and June receive slightly less precipitation than other months however, the soils are still moist from snowmelt.
Frost-free period: 40 to 75 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Wander and Sig series. Wander soils are loamy-skeletal. Sig soils are shallow to a lithic contact.
DRAINAGE AND PERMEABILITY: Well drained; slow to medium runoff; moderately slow or moderate permeability.
USE AND VEGETATION: Used for livestock grazing and wildlife habitat. Native vegetation is principally Thurber's fescue, nodding brome, Parry's danthonia, needlegrass, American vetch, and bluegrass.
DISTRIBUTION AND EXTENT: The mountains of southwestern Colorado, LRR E, MLRA 48A. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.
SERIES ESTABLISHED: Summit County, Utah, 1972.
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - from 0 to 11 inches. (A horizon)
Argillic horizon - from 11 to 46 inches. (Bt1, Bt2, and Bt3 horizons)
Particle-size control section - the zone from 11 to 31 inches (the upper 20 inches of the argillic horizon)
The superactive CEC activity class is presumed for this series based on the general trend indicated by lab data throughout this region.
The 02/1999 revision moves the type location to the Animas-Dolores Soil Survey Area, Colorado from Summit County, Utah. This series is currently not correlated in Utah. The range in characteristics and geographic setting is extensively revised to include only soils as mapped in Colorado, in MLRA 48A.
Keys to Soil Taxonomy: Series classified according to Eighth Edition, 1998.