LOCATION TOSCA UTEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Typic Calciustolls
TYPICAL PEDON: Tosca gravelly sandy loam, rangeland (Colors are for air-dry soil unless otherwise noted). The surface is covered by 20 percent gravel, cobbles, and stones.
0i--0 to 2 inches; slightly decomposed leaves, twigs and litter.
A1--2 to 5 inches; brown (10YR 5/3) gravelly sandy loam, dark brown (7.5YR 3/2) moist; moderate very fine granular structure; soft, very friable, slightly sticky and slightly plastic; few coarse and many very fine roots; common very fine and fine tubular pores; 10 percent gravel, 5 percent cobbles in horizon; slightly effervescent, (8 percent calcium carbonate equivalent); carbonates are disseminated; moderately alkaline (pH 8.0); clear smooth boundary. (3 to 9 inches thick)
A2--5 to 11 inches; dark yellowish brown (10YR 4/4) gravelly sandy loam, very dark grayish brown (10YR 3/2) moist; moderate very fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; few coarse medium and fine and common very fine roots; few medium and common very fine and fine tubular pores; 10 percent angular gravel, 5 percent cobbles; slightly effervescent, (13 percent calcium carbonate equivalent), carbonates are disseminated and thin coatings on rock fragments; moderately alkaline (pH 8.0); clear wavy boundary. (0 to 7 inches thick)
Bk1--11 to 19 inches; pale brown (10YR 6/3) very gravelly sandy loam, brown (10YR 5/3) moist; weak medium and fine subangular blocky structure; hard, very friable, slightly sticky and slightly plastic; few coarse medium fine and common very fine roots; few fine and very fine tubular pores; 25 percent angular gravel and 15 percent cobbles; strongly effervescent, (37 percent calcium carbonate equivalent), carbonates are disseminated and thin coatings on rock fragments; moderately alkaline (pH 8.2); gradual smooth boundary. (7 to 19 inches thick)
Bk2--19 to 39 inches; light gray (10YR 7/2) very cobbly sandy loam, brown (10YR 5/3) moist; massive; hard, very friable, slightly sticky and slightly plastic; few very fine, fine and medium roots; common fine, many very fine tubular pores; 25 percent cobbles, 10 percent stones, 25 percent angular gravel; strongly effervescent, (26 percent calcium carbonate equivalent), carbonates are disseminated and thin coatings on rock fragments; moderately alkaline (pH 8.4); clear wavy boundary. (7 to 26 inches thick)
Bk3--39 to 53 inches; light gray (10YR 7/2) extremely stony sandy loam, brown (10YR 5/3) moist; massive; hard, very friable, slightly sticky and slightly plastic; few very fine, fine and medium roots; common very fine and fine tubular pores; 50 percent stones, 20 percent channery fragments, 10 percent cobbles; strongly effervescent, (22 percent calcium carbonate equivalent); carbonates are disseminated and thin coatings on rock fragments; moderately alkaline (pH 8.4); clear irregular boundary. (0 to 14 inches thick)
C--53 to 60 inches; pale brown (10YR 6/3) extremely stony sandy loam, brown (7.5YR 4/2) moist; massive; slightly hard, very friable, slightly sticky and slightly plastic; few very fine and fine roots; common very fine and fine tubular pores; 40 percent stones, 20 percent cobbles, 10 percent angular gravel; slightly effervescent, (20 percent calcium carbonate equivalent), carbonates are disseminated; moderately alkaline (pH 8.4); abrupt wavy boundary. (0 to 22 inches thick)
R--60 inches; sandstone.
TYPE LOCATION: Grand County, Utah; about 40 miles southwest of Bonanza, 1,700 feet east and 2,000 feet north of the southwest corner of sec. 34, T. 15 1/2 S., R. 24 E SLBM; P R Springs, Utah USGS quadrangle; 39 degrees, 27 minutes, 38 seconds north latitude and 109 degrees, 15 minutes, 10 seconds west longitude. NAD 27.
RANGE IN CHARACTERISTICS: Depths are measured from the top of the mineral soil surface.
Soil moisture: It is moist in all parts of the moisture control section 40 to 45 percent of the time the soil temperature exceeds 41 degrees F. The soil moisture control section is usually moist in some part during late spring to early fall, and intermittently dry in late fall; typic ustic soil moisture regime.
Mean annual soil temperature: 40 to 45 degrees F.
Mean summer soil temperature: 61 to 65 degrees F.
Depth to calcic horizon: 7 to 15 inches
Depth to lithic contact: 40 to 60 inches to sandstone bedrock
Some pedons have a lithologic discontinuity at 14 to 51 inches
Mollic epipedon: 7 to 15 inches thick
Particle-size control section: 10 to 18 percent clay and 35 to 65 percent rock fragments
A horizon:
Hue: 7.5YR or 10YR
Value: 4 or 5 dry, 3 or 4 moist
Chroma: 2 through 4 dry or moist
Calcium carbonate equivalent: 2 to 15 percent
Reaction: slightly alkaline or moderately alkaline
Bk horizon:
Hue: 7.5YR to 2.5Y
Value: 5 to 7 dry, 4 to 6 moist
Chroma: 2 to 4 dry or moist
Texture: very gravelly sandy loam, very gravelly loam, cobbly loam, very cobbly sandy loam, very cobbly fine sandy loam, very stony loam, extremely stony loam, very flaggy loam
Rock fragments: 15 to 80 percent
Calcium carbonate equivalent: 15 to 40 percent; up to 45 percent below 40 inches
C horizons:
Hue: 7.5YR to 2.5Y
Value: 5 to 7 dry, 4 to 6 moist
Chroma: 2 to 4 dry or moist
Texture: extremely stony sandy loam, very cobbly sandy loam, very channery loam, and very stony loam
Calcium carbonate equivalent: 10 to 20 percent
Rock fragments: 50 to 75 percent
Reaction: moderately alkaline or strongly alkaline
The Bw horizon, where present, has colors similar to the Bk horizons. It is too thin for a cambic horizon.
The 2C horizon, where present, has colors similar to the C horizons.
COMPETING SERIES: Current competitors are the Bigsheep, Eager, Saddlehorse and Winspect series.
Bigsheep,
Winspect and
Saddlehorse soils contain more than 18 percent clay in the control section.
Bigsheep, Eager and Winspect soils are very deep.
Saddlehorse soils have a paralithic contact with shale at 20 to 40 inches.
GEOGRAPHIC SETTING:
Parent material: slope alluvium and colluvium derived from sandstone and shale
Landform: backslopes of mountains
Elevation: 6,500 to 9,400 feet
Slope: 20 to 80 percent
Mean annual temperature: 38 to 46 degrees F.
Average annual precipitation: 16 to 22 inches
Precipitation Pattern: Wettest months are May to Ootober and driest months are February to April.Mean annual temperature: 38 to 46 degrees F.
Freeze-free period: 60 to 90 days
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Utso, Sowcan, Pathead, Seeprid, and Veatch soils. Sowcan, Seeprid and Utso soils have mollic epipedons thicker than 16 inches. Pathead and Veatch soils are 20 to 40 inches deep.
DRAINAGE AND PERMEABILITY: Well drained, medium and high runoff, moderately rapid or moderate permeability.
USE AND VEGETATION: These soils are used for rangeland, recreation and wildlife habitat. Present vegetation is mountain big sagebrush, Utah serviceberry, birchleaf mountainmahogany, antelope bitterbrush and Gambel oak. This soil has been correlated to the Mountain Very Steep Stony Loam 048AY473UT range site at the type location in Utah.
DISTRIBUTION AND EXTENT: Northeastern and central Utah and northwestern Colorado. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Douglas Plateau Area, Parts of Garfield and Mesa Counties, Colorado, 1988.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon: The zone from 2 to 11 inches. (A1, A2)
Calcic horizon - the zone from 11 to 53 inches. (Bk1, Bk2, Bk3)
Lithic contact: The contact with sandstone bedrock at 60 inches. (R layer)
The classification was changed from Typic Calciborolls to frigid Typic Calciustolls 12/98.
Taxonomic version: Tenth Edition, 2006.
ADDITIONAL DATA: NSSL number 80P2759-2764 and 80P2788-2795 sample analysis October 1981.