LOCATION VENNOB UTEstablished Series
TAXONOMIC CLASS: Clayey-skeletal, smectitic, frigid Lithic Argixerolls
TYPICAL PEDON: Vennob very gravelly loam, rangeland. (Colors are for dry soil unless otherwise noted.)
The soil surface is covered with 2 percent stones, 5 percent cobbles and 50 percent gravel.
A--0 to 2 inches; grayish brown (10YR 5/2) very gravelly loam, very dark grayish brown (10YR 3/2) moist; weak fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; common fine and very fine roots; few medium, many fine and very fine pores; 40 percent gravel; slightly alkaline (pH 7.4); abrupt wavy boundary.
BA--2 to 5 inches; grayish brown (10YR 5/2) very gravelly clay loam, very dark grayish brown (10YR 3/2) moist; moderate medium subangular blocky structure; hard, firm, sticky and plastic; few medium, common fine and very fine roots; many fine and very fine pores; 40 percent gravel; slightly alkaline (pH 7.6); clear wavy boundary.
Bt--5 to 17 inches; brown (7.5YR 5/4) very gravelly clay loam, dark brown (7.5YR 4/2) moist; strong medium subangular blocky structure; hard, firm, sticky and plastic; few medium, fine and very fine roots; many fine and very fine pores; many distinct clay films on faces of peds and lining pores; 50 percent gravel; slightly alkaline (pH 7.6); abrupt wavy boundary.
R--17 inches; hard igneous bedrock.
TYPE LOCATION: Iron County, Utah; about 5.5 miles southwest of Steamboat Mountain in Hamlin Valley, about 400 feet north and 400 feet east of the southwest corner of section 22, T. 32 S., R. 18 W; Steamboat Mountain Quadrangle; lat. 38 degrees 0 minutes 6 seconds N. and long. 113 degrees 51 minutes 31 seconds W.
RANGE IN CHARACTERISTICS: The soil moisture regime is xeric bordering on aridic. The mean annual soil temperature is 45 to 47 degrees F, and mean summer soil temperature is 59 to 62 degrees F.
These soils are noncalcareous throughout. Depth to the lithic contact ranges from 10 to 20 inches. The particle size control section has 35 to 40 percent clay. The igneous rock fragment content ranges from 35 to 50 percent and are dominantly gravel and cobble size. Reaction is neutral or slightly alkaline throughout. The mollic epipedon is 7 to 10 inches thick when mixed and includes part but not all of the argillic horizon.
The A horizon has hue of 10YR, value of 4 or 5, 2 or 3 moist, and chroma of 2 or 3. Texture is a very gravelly loam. Rock fragment content is 35 to 60 percent.
The BA horizon has hue of 10YR, value of 4 or 5, 2 or 3 moist, and chroma of 2 or 3. Texture is a very cobbly loam or very gravelly clay loam. Rock fragment content is 35 to 50 percent.
The Bt horizon has hue of 7.5YR or 10YR, value of 5 or 6, 3 or 4 moist, and chroma of 2 to 4. Texture is a very cobbly clay loam or very gravelly clay loam. Rock fragment content is 35 to 50 percent.
COMPETING SERIES: These are the Ateron (OR), Camool (T WA), Canest (T OR), Chen (NV), Douhide(NV), Graley (NV), Harlow (WA), Itca (NV) and Wallsburg (UT) soils. Ateron soils have 40 to 50 percent clay in the particle size control section. Camool soils contain 7 to 25 percent volcanic glass in the top 5 to 9 inches and have 2Bt horizons. Canest soils have bedrock at 5 to 10 inches, and the mollic epipedon includes the entire soil. Chen soils have 40 to 55 percent clay in the particle size control section. Douhide soils have an aridic soil moisture regime and are dry for 90 or more consecutive days during the summer and fall. Graley soils have mollic epipedons that do not include any part of the argillic horizon. Harlow soils have mollic colors throughout the Bt horizon. Itca soils have an abrupt boundary between the A and Bt horizon. Wallsburg soils have more than 50 percent cobbles and stones in the particle size control section.
GEOGRAPHIC SETTING: Vennob soils are on mountain slopes. Slope range from 15 to 40 percent. The soil formed in residuum and colluvium from igneous rocks. The average annual precipitation is 12 to 16 inches. The mean annual air temperature ranges from 43 to 45 degrees F. Elevations range from 6,500 to 7,800 feet and the freeze free period is 70 to 90 days.
GEOGRAPHICALLY ASSOCIATED SOILS: This is the Bodacious soil. Bodacious soils are loamy-skeletal and lack an argillic horizon.
DRAINAGE AND PERMEABILITY: Well drained; medium to rapid runoff; moderately slow permeability.
USE AND VEGETATION: These soils are used for rangeland. Important plants are pinyon, Utah juniper, black sagebrush, antelope bitterbrush, mountain big sagebrush, bluebunch wheatgrass and Indian ricegrass.
DISTRIBUTION AND EXTENT: Southwestern Utah. MLRA 28A. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Phoenix, Arizona
SERIES ESTABLISHED: Iron County, Utah, Iron-Washington Area Soil Survey Area, 1997.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - The zone from the soil surface to 7 inches (A and BA horizons and the upper 2 inches of the Bt horizon).
Argillic horizon - The zone from 5 to 17 inches (Bt horizon).
Lithic contact - The boundary at 17 inches (R horizon).
The classification is based on the "Keys to Soil Taxonomy, Eighth Edition, 1998".