LOCATION AVON UT+IDEstablished Series
TAXONOMIC CLASS: Fine, smectitic, mesic Calcic Pachic Argixerolls
TYPICAL PEDON: Avon silty clay loam, cultivated. (Colors are for dry soil unless otherwise noted.)
A1--0 to 9 inches; very dark gray (10YR 3/1) light silty clay loam, black (10YR 2/1) moist; moderate medium granular structure; slightly hard, friable, sticky, slightly plastic; many fine and medium roots; common fine and medium pores; neutral (pH 7.3); clear wavy boundary. (6 to 15 inches thick.)
A2--9 to 12 inches; very dark gray (10YR 3/1) silty clay loam, black (10YR 2/1) moist; weak medium prismatic structure parting to moderate fine angular blocky structure; hard, firm, sticky, plastic; common fine and medium pores; common fine and medium roots; few thin clay films in pores; neutral (pH 7.0); clear wavy boundary. (0 to 8 inches thick.)
Bt1--12 to 18 inches; dark gray (10YR 4/1) light silty clay, very dark gray (10YR 3/1) moist; weak medium prismatic structure parting to moderate medium angular blocky structure; hard, firm, sticky plastic; common fine pores; few fine and medium roots; common faint clay films in pores and on some peds; slightly alkaline (pH 7.7); clear smooth boundary. (5 to 8 inches thick.)
Bt2--18 to 27 inches; dark grayish brown (10YR 4/2) silty clay, very dark grayish brown (10YR 3/2) moist; weak medium prismatic structure parting to strong medium angular blocky structure; very hard, very firm, very sticky, very plastic; common fine pores; few fine roots; many faint clay films on ped faces and in pores; slightly alkaline (pH 7.6); clear smooth boundary. (8 to 22 inches thick.)
Ck--27 to 34 inches; light gray (2.5Y 7/2) silt loam, grayish brown (2.5Y 5/2) moist; weak medium subangular blocky structure; slightly hard, friable, slightly sticky, slightly plastic; very strongly calcareous; lime is veined and flaky; moderately alkaline (pH 8.3); clear smooth boundary. (6 to 20 inches thick.)
C--34 to 60 inches; light gray (2.5Y 7/2) silt loam, grayish brown (2.5Y 5/2) moist; massive; slightly hard, friable; strongly calcareous, lime is disseminated, moderately alkaline (pH 8.2).
TYPE LOCATION: Cache County, Utah; northeast of Richmond; 800 feet west of the south 1/4 corner of sec. 13, T. 14 N., R. 1 E.; Richmond USGS quad; Latitude 41 degrees 56 minutes 52 seconds N. and Longitude 111 degrees 46 minutes 44 seconds W.
RANGE IN CHARACTERISTICS: The mean annual soil temperature ranges from 48 degrees to 51 degrees F., and the mean summer soil temperature from 65 degrees to 68 degrees F. The soil is usually moist, but it is dry in all parts of the 4 to 12 inch depth for more than 60 consecutive days in more than 7 out of 10 years.
The soil contains a component of volcanic ash. The mollic epipedon ranges from 20 to 36 inches in thickness and includes the A horizon and the upper part of the B horizon.
The A horizon has hue of 10YR, value of 3 or 4 dry and 1 or 2 moist, and chroma between 1 and 2. Structure ranges from weak to moderate, fine to medium granular. The A horizon ranges from slightly acid to slightly alkaline and is dominantly noncalcareous, but some are slightly calcareous due to recent deposits or rodent activity.
The Bt horizon has hue of 10YR or 2.5Y, value of 4 through 6 dry and 2 through 4 moist, and dominant chroma of 1 or 2, except that where hue is 2.5Y some pedons have chroma of 3. The B2t horizon is silty clay, clay or heavy silty clay loam. it has weak to strong, medium prismatic or moderate angular blocky structure. Clay films range from common to continuous. Reaction ranges from slightly acid to slightly alkaline.
The C horizon has hue of 10YR, 2.5Y, or 5Y, value of 6 through 8 dry and 4 through 7 moist, and chroma of 2 or 3. It ranges from silty clay loam to silt loam, and some pedons contain 10 to 40 percent of unweathered tuffaceous pebbles and cobblestones.
COMPETING SERIES: Gelsinger (OR) - doesn't include hue of 2.5Y in the Bt and contains rock fragments.
Geoconda (WA) - has basalt bedrock at 40 to 60 inches.
McMurdie (UT) - have chroma of 2 or 3 in the A horizon and lack a component of volcanic ash.
Neconda (WA) - has basalt bedrock at 20 to 40 inches.
GEOGRAPHIC SETTING: Avon soils are on high lake terraces at elevations ranging from 4,600 to 5,150 feet. Slope gradients are dominantly 1 to 10 percent and range from 0 to 20 percent. Avon soils formed in lacustrine or alluvial fan sediments that contain a component of volcanic ash. The climate is moist subhumid. The average annual precipitation is about 18 inches, the mean annual temperature is 45 degrees to 47 degrees F., and mean summer temperature is 65 degrees to 67 degrees F. The freeze-free period ranges from 110 to 140 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Mendon soils, and the Collinston, Brookston, and Wheelon soils. Collinston and Wheelon soils lack argillic horizons. Wheelon soils, in addition, lack mollic epipedons. Crookston soils have loam series control sections.
DRAINAGE AND PERMEABILITY: Well drained. Permeability is slow or moderately slow. Runoff is medium to high.
USE AND VEGETATION: These soils are used mostly for growning small grains, alfalfa, and safflower without irrigation. The native vegetation is big sagebrush, western wheatgrass, balsamroot, and bluebunch wheatgrass.
DISTRIBUTION AND EXTENT: Northern Utah and southern Idaho. This series is not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Cache Valley Area, Utah, 1913.