LOCATION STEPMOUNT UTEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, mesic Lithic Argixerolls
TYPICAL PEDON: Stepmount extremely cobbly loam, on a north facing, convex to concave, 40 percent slope in Utah juniper at an elevation of 5,439 feet. (Colors are for dry soil unless otherwise noted). The surface is covered by 40 percent cobbles, 20 percent gravel, and 10 percent stones of andesite origin and subangular in shape.
A--0 to 10 inches; dark grayish brown (10YR 4/2) extremely cobbly loam, very dark grayish brown (10YR 3/2) moist; weak medium subangular blocky structure parting to moderate fine and very fine granular; soft, very friable, slightly sticky and slightly plastic; many very fine, common fine, few medium and coarse roots; many very fine, common fine tubular and interstitial pores; 10 percent gravel, 20 percent cobbles, 5 percent stones; slightly alkaline (7.4); clear wavy boundary. (7 to 12 inches thick)
Bt--10 to 15 inches; grayish brown (10YR 5/2) very cobbly loam, dark grayish brown (10YR 4/2) moist; weak medium subangular blocky structure parting to moderate fine and very fine subangular blocky; hard, friable, slightly sticky and slightly plastic; many very fine, few fine, medium, and coarse roots; many very fine, few fine tubular pores; few discontinuous faint clay films on ped faces; 20 percent gravel, 30 percent cobbles, 5 percent stones; slightly alkaline (pH 7.6); abrupt wavy boundary. (5 to 10 inches thick)
Btk--15 to 19 inches; pale brown (10YR 6/3) extremely cobbly loam, brown (10YR 5/3) moist; weak fine and medium subangular blocky structure; hard, friable, slightly sticky and slightly plastic; many very fine, few fine, medium and coarse roots; common very fine, few fine tubular pores; few discontinuous faint clay films on ped faces; 20 percent gravel, 40 percent cobbles, 5 percent stones; slightly effervescent, (8 percent calcium carbonate equivalent), carbonates are disseminated and segregated in few fine irregular shaped soft masses and in less than 1 mm thick coatings on rock fragments; moderately alkaline (pH 8.2); gradual wavy boundary. (3 to 8 inches thick)
R--19 inches; slightly weathered andesite, with less than 1 mm thick coatings of calcium carbonate on bedrock and in cracks.
TYPE LOCATION: Utah County, Utah; about 3 miles south of Tickville Spring; located about 100 feet north and 2,100 feet east of the southwest corner of sec. 11, T. 5 S., R. 2 W.; Tickville Spring, Utah USGS quad; lat. 40 degrees 23 minutes 28.55 seconds N.. and long. 112 degrees 01 minutes 38.03 seconds W., NAD 27
RANGE IN CHARACTERISTICS:
Soil moisture regime: xeric moisture regime bordering on aridic. Soil moisture control section is dry for greater than 60 consecutive days following the summer solstice.
Soil temperature regime: mesic
Mean annual soil temperature: 47 to 55 degrees F.
Surface rock fragments: 25 to 75 percent subangular andesite stones, cobbles, and gravel
Particle-size control section: 18 to 35 percent clay; 50 to 80 percent rock fragments, dominantly cobbles and gravel with minor stones; 1 to 15 percent calcium carbonate equivalent
Depth to lithic contact: 10 to 20 inches to andesite bedrock
Depth to secondary calcium carbonate: 9 to 18 inches
Thickness of the mollic epipedon: 7 to 15 inches, may include the upper part of the argillic horizon
A horizon:
Hue: 10YR
Value: 4 or 5 dry, 2 or 3 moist
Chroma: 1 to 3
Texture: loam, clay loam
Rock fragments: 35 to 75 percent, dominantly stones and cobbles with minor gravel
Reaction: neutral to slightly alkaline
Bt horizon:
Hue: 7.5YR or 10YR
Value: 4 to 6 dry, 3 to 5 moist
Chroma: 2 to 4
Texture: clay loam, silty clay loam, silt loam, loam
Rock fragments: 50 to 80 percent, dominantly cobbles and gravel with minor stones
Reaction: neutral to slightly alkaline
Btk horizon:
Hue: 7.5YR or 10YR
Value: 4 to 6 dry, 3 to 5 moist
Chroma: 2 to 4
Texture: clay loam, silty clay loam, loam, silt loam
Rock fragments: 50 to 80 percent, dominantly cobbles and gravel with minor stones
Calcium carbonate equivalent: 3 to 15 percent
Reaction: slightly alkaline to moderately alkaline
COMPETING SERIES: These are the Argabak (WA), Bellehelen (NV), Brier (NV), Chinabutte (ID), Clovercreek (OR), Duco (NV), Gwin (WA), Horseflat (WA), Ocud T (NV), Orhood (CA), Reywat (ID), Shepridge T (UT), Upatad (NV), and Windry (WA) series.
Argabak: includes depths to bedrock at less than 10 inches, and has no accumulations of secondary calcium carbonate.
Bellehelen, Brier, Duco, Horseflat, Ocud, and Orhood: have aridic moisture regimes and no accumulations of secondary calcium carbonate.
Reywat: has an aridic moisture regime.
Chinabutte, Gwin, and Windry: have no accumulations of secondary calcium carbonate.
Clovercreek: has no accumulations of secondary calcium carbonate and is derived from greenstone parent material.
Shepridge: is derived from quartzite parent material.
Upatad: has an aridic moisture regime and has accumulations of silica.
GEOGRAPHIC SETTING: Stepmount soils.
Parent material: colluvium and alluvium over residuum derived from andesite.
Landform: hillslopes, and mountain slopes.
Slopes: 8 to 60 percent
Elevation: 4,800 to 6,700 feet
Mean annual air temperature: 45 to 53 degrees F.
Mean annual precipitation: 14 to 16 inches.
Wettest months: October to May.
Driest months: June to September.
Frost-free period: 100 to 140 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Beefhollow, Dry Creek, Reebok, and Tickville series.
Beefhollow soils are very deep and are under Gambel oak.
Dry Creek soils are very deep and are on fan remnants.
Reebok soils have a petrocalcic horizon and are on fan remnants.
Tickville soils have bedrock at 20 to 40 inches and are under Gambel oak.
DRAINAGE AND PERMEABILITY: Well drained, medium or high runoff, moderate or moderately slow permeability.
USE AND VEGETATION: Wildlife habitat and rangeland. Some potential native plants are Utah juniper, singleleaf pinyon, bluebunch wheatgrass, Nevada bluegrass, and Indian ricegrass. These soils have been correlated to Upland Shallow Loam (Wyoming Big Sagebrush) - 047AY320UT, and Upland Shallow Loam (Utah juniper-singleleaf pinyon) - 047AY324UT range sites in Utah.
DISTRIBUTION AND EXTENT: Northern Utah. LRR D, MLRA 28A. This series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona.
SERIES ESTABLISHED: Utah county, Utah. 1999. The name coined from a nearby geographic location.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon: from 0 to 10 inches (A horizon).
Argillic horizon: from 10 to 19 inches (Bt and Btk horizons).
Lithic contact: Andesite bedrock at 19 inches. (R horizon)
Keys to Soil Taxonomy: Eighth Edition 1998