LOCATION AGASSIZ UT+ID NVEstablished Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Lithic Haploxerolls
TYPICAL PEDON: Agassiz very cobbly silt loam--native grasses and shrubs (Colors are for air-dry soil unless otherwise stated.)
A1--0 to 7 inches; brown (7.5YR 5/3) very cobbly silt loam, dark brown (10YR 3/3) moist; moderate medium granular structure; soft, very friable, slightly plastic; many fine and medium roots; neutral (pH 7.1); clear wavy boundary. (2 to 11 inches thick)
A2--7 to 18 inches; brown (7.5YR 5/3) very cobbly silty clay loam, dark brown (7.5YR 3/3) moist; weak fine and medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; many fine and medium roots; many very fine, discontinuous, interstitial in ped pores; neutral (pH 7.2); abrupt broken boundary. (5 to 14 inches thick)
R--18 inches; fractured limestone.
TYPE LOCATION: Cache County, Utah; South Cottonwood Canyon; 1,200 feet north and 1,200 feet west of the SE corner of sec. 19, T. 10 N., R. 3 E.
RANGE IN CHARACTERISTICS: The mean annual soil temperature ranges from 33 to 46 degrees F., and the mean summer soil temperature ranges from 59 to 70 degrees F. The soils are usually moist but are dry in all parts of the soil moisture control section for 45 to 60 consecutive days in more than 7 out of 10 years. The soil moisture regime is typic xeric.
The mollic epipedon ranges in thickness from 7 to 19 inches. Depth to a lithic contact is 7 to 20 inches. The rock fragments are dominantly limestone but also include calcareous quartzite, calcareous sandstone, and dolomite. These soils are generally noncalcareous but are slightly calcareous to moderately calcareous in spots in some pedons. The particle-size control section ranges from 18 to 35 percent clay and is slightly acid to slightly alkaline. The rock fragments range from 20 to 60 percent by volume in the upper A horizon and 35 to 80 percent in the lower horizon and may contain up to 10 percent stones. The A horizon has hue of 10YR to 5YR, value of 3 to 5 dry, 2 or 3 moist, and chroma of 2 to 4. It is very cobbly or cobbly silt loam or silty clay loam to extremely stony loam. Structure is weak to moderate, fine to medium, subangular blocky or granular. A thin C horizon occurs between the A horizon and the bedrock in some pedons.
COMPETING SERIES: These are the Alomax (T CA), Anatone (WA), Bluecanyon (T OR), Bocker (WA), Dipcreek (T ID), Falula (UT), Foxol (UT), Gando (NV), Gomine (UT), Grink (NV), Hogsby (MT), Kenypeak (CA), Little Pole (UT), Nayrib (ID), Onaqui (UT), Rexmont (UT), Swanner (UT) and Van Wagoner (UT) series. Alomax, Dipcreek, Gando, Grink Hogsby and Van Wagoner soils have less than 18 percent clay in the particle-size control section. Anatone, Foxol, Little Pole and Swanner soils have cambic horizons. Bluecanyon soils formed in igneous rock and contain less than 18 percent clay in the particle-size control section, Bocker soils have cambic horizons and are dry for 75 to 90 consecutive days following the summer solstice. Falula soils have Bk horizons and are moderately calcareous to strongly calcareous. Gomine soils have a cambic horizon and are dry for more than 60 consecutive days, Kenypeak soil aren't in the OSD file, Nayrib soils contain 12 to 18 percent clay and are are less than 10 inches to bedrock. Onaqui soils formed in quartzite and the clay range is 18 to 27 percent, Rexmont soils are calcareous in the lower horizon and are moderately alkaline or strongly alkaline.
GEOGRAPHIC SETTING: Agassiz soils are at elevations of 5,200 to 8,700 feet. They are on strongly sloping and very steep, dominantly south and west-facing mountain slopes with gradients of 4 to 70 percent. The soils formed in colluvium over fractured, weathering limestone. The climate is moist subhumid or humid, the average annual precipitation is about 16 to 22 inches. The mean annual temperature is 31 to 47 degrees F., and the average summer temperature is 59 to 64 degrees F. Freeze-free period is 30 to 100 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Abes, Bradshaw, Burgi, Dateman, Geertsen, Horrocks, Hourglass, and Mult soils. Abes soils are fine textured, have albic and argillic horizons and have an average summer soil temperature less than 59 degrees F. Bradshaw soils are more than 20 inches deep to bedrock. Burgi soils have mollic epipedons more than 20 inches thick. Dateman soils have mollic epipedons more than 20 inches thick, have cambic horizons, and are more than 20 inches deep over bedrock. Geertsen, Hourglass and Mult soils are more than 20 inches deep to bedrock. Geertsen and Horrocks soils have argillic horizons. Hourglass and Mult soils have argillic horizons with less than 35 percent cobbles and gravel and have average summer temperature of less than 59 degrees F.
DRAINAGE AND PERMEABILITY: Somewhat excessively drained; medium to high runoff; moderate or moderately rapid permeability.
USE AND VEGETATION: These soils are used for watershed, rangeland and wildlife. Present vegetation is big sagebrush, curlleaf mountainmahogany, bluebunch wheatgrass, snowberry, buckwheat, serviceberry, chokecherry and some juniper. In places some open stunted stands of Douglas-fir, white fir and aspen occur.
DISTRIBUTION AND EXTENT: Mountain areas of northern and central Utah. This series is moderately extensive. MLRA 28A, 47.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Cache County (Cache Valley Area), Utah, 1969.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - from 0 to 18 inches (A1, A2 horizons).
Lithic contact at 18 inches (R layer).
Particle-size control section the zone from 10 to 18 inches (part of the A2 horizon).
Classification: Keys to Soil Taxonomy, Tenth Edition, 2006.