LOCATION HILLTO UT

Tentative Series
Rev. FRR/SJJ/JMB
01/2016

HILLTO SERIES

The Hillto series consists of moderately deep, well drained, moderately permeable soils that formed in mixed alluvium and glacial outwash derived dominantly from sandstone, limestone, shale, and quartzite. These soils occur on outwash fans and have slopes of 0 to 8 percent. The mean annual air temperature is about 5 degrees C. (41 deg. F.) and the average annual precipitation is about 330 mm (13 in.).

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Petrocalcic Calciustepts

TYPICAL PEDON: Hillto loam on a 3 percent slightly convex-concave slope in rangeland. (Colors are for air dry soil unless otherwise noted.)

A--0 to 10 cm; brown (7.5YR 4/4) loam, dark brown (7.5YR 3/4) moist; weak thin platy structure that parts to weak fine granular; soft, friable, slightly sticky, slightly plastic; common very fine and fine roots; few very fine tubular pores; 5 percent gravel; slightly alkaline (pH 7.6); abrupt smooth boundary. (3 to 10 cm thick)

Bw--10 to 20 cm; brown (7.5YR 5/4) loam, brown (7.5YR 4/4) moist; moderate medium subangular blocky structure that parts to moderate fine subangular blocky; slightly hard, friable, slightly sticky, plastic; common very fine and fine, few medium and coarse roots; few very fine and fine tubular pores; 5 percent gravel; slightly effervescent, carbonates are disseminated; moderately alkaline (pH 8.2); abrupt smooth boundary. (10 to 28 cm thick)

Bk1--20 to 30 cm; pink (7.5YR 7/4) gravelly loam, light brown (7.5YR 6/4) moist; moderate fine and medium subangular blocky structure; hard, firm, sticky, plastic; common very fine and fine, few medium roots; few very fine tubular pores; 20 percent gravel; strongly effervescent, carbonates are veined and disseminated; moderately alkaline (pH 8.4); abrupt smooth boundary. (10 to 18 cm thick)

Bk2--30 to 81 cm; very pale brown (10YR 7/3) very gravelly loam, pale brown (10YR 6/3) moist; massive; very hard, very firm, slightly sticky, plastic; few very fine and fine roots; 35 percent hardpan gravel fragments and 20 percent gravel; strongly effervescent, carbonates are veined, in soft masses and disseminated; strongly alkaline (pH 8.6); clear smooth boundary. (28 to 46 cm thick)

Bkm--81 cm; indurated carbonate cemented hardpan.

TYPE LOCATION: Duchesne County, Utah; about 0.2 miles south and 0.1 miles east of Talmage; 2,200 feet south and 500 feet east of the NW corner of Section 2, T. 2 S., R. 5 W. Uintah Special Base and Meridian.

RANGE IN CHARACTERISTICS: The depth to a carbonate cemented hardpan ranges from 50 to 100 cm (20-40 in.). Rock fragments in the control section are gravel and gravel size hardpan fragments and average 35 to 60 percent. The mean annual soil temperature is 5 to 8 deg. C (42-47 deg. F.), and the mean summer soil temperature is 16 to 19 deg. C (61-65 deg. F). These soils are dry in all parts 40 percent of the time or more cumulative when the soil temperature at a depth of 50 cm is above 5 degrees C. (41 deg. F). The soil moisture regime is Ustic, bordering on Aridic.

The A horizon has hue of 7.5YR or 10YR and chroma of 3 or 4 dry, 2 to 4 moist. It is sandy loam or loam and ranges from 0 to 5 percent gravel. The A horizon is non-effervescent or slightly effervescent and slightly alkaline or moderately alkaline.

The Bw horizon has hue of 7.5YR or 10YR, value of 5 or 6 dry, 3 or 4 moist. It is sandy loam or loam and contains less than 15 percent gravel and gravel size hardpan fragments. The Bw horizon is non-effervescent to slightly effervescent, and moderately alkaline or strongly alkaline.

The Bk horizon has hue of 7.5YR or 10YR, value of 6 to 8 dry, 5 to 7 moist, and chroma of 2 to 4 dry, 3 or 4 moist. It is dominantly very gravelly loam, very gravelly sandy loam, or extremely gravelly loam. The upper part of the Bk horizon has gravelly loam in some pedons. The Bk horizon is strongly or very strongly effervescent, and moderately alkaline or strongly alkaline.

COMPETING SERIES: Presently there are no competing series in this family.

GEOGRAPHIC SETTING: The Hillto soils are on outwash fans. Slopes range from 0 to 8 percent. The soils formed in mixed alluvium and glacial outwash derived from sandstone, limestone, shale, and quartzite. Elevations range from 1,770 to 2,135 meters (5,800-7,000 ft.). The mean annual temperature ranges from 4 to 7 degrees C. (39-44 deg. F.), and the average annual precipitation is from 305 to 356 mm (12-14 in). Frost-free season is 85 to 105 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bluerim, Havre, Tupinto, and Stunner soils. The Bluerim, Tupinto, and Stunner soils have an argillic horizon. The Havre soils do not have a hardpan, are stratified in the C horizon and average between 18 and 35 percent clay.

DRAINAGE AND PERMEABILITY: Well drained; medium runoff, moderate permeability.

USE AND VEGETATION: These soils are used for rangeland and irrigated hay and pasture. Principle vegetation is big sagebrush, woody phlox, Indian ricegrass and bluebunch wheatgrass.

DISTRIBUTION AND EXTENT: Northeastern Utah, of small extent; about 3,000 acres have been mapped.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana

SERIES PROPOSED: Duchesne County, Utah, 1980. The name is coined.

REMARKS: Keys to Taxonomy 12th Edition 2014.
Diagnostic Horizons present in this soil are:
Ochric Epipedon; 0 to 20 cm.
Calcic Horizon; 20 to 81 cm.
Indurated carbonate cemented hardpan; 81cm.
(The previous classification of this soil was Calcic Petrocalcids)

National Cooperative Soil Survey
U.S.A.