LOCATION SHOWALTER UT+COEstablished Series
TAXONOMIC CLASS: Clayey-skeletal, smectitic, frigid Typic Argiustolls
TYPCIAL PEDON: Showalter gravelly loam--rangeland. (Colors are for air-dry soil unless otherwise stated.)
A--0 to 5 inches; dark brown (10YR 4/3) gravelly loam, very dark brown (10YR 2/2) moist; weak medium granular structure; soft, friable, slightly sticky and slightly plastic; many medium, fine and very fine roots; common fine and very fine pores; 15 percent subrounded pebbles; neutral (pH 7.5); abrupt smooth boundary. (3 to 7 inches thick)
Bt1--5 to 10 inches; dark brown (10YR 4/3) gravelly loam, very dark brown (10YR 2/2) moist; weak medium prismatic structure parting to weak fine subangular blocky; hard, friable, slightly sticky and slightly plastic; many medium, fine, and very fine roots; common fine and very fine pores; common thin clay films on faces of peds and in pores; 15 percent each of subrounded pebbles and cobbles; neutral (pH 7.0); abrupt smooth boundary. (0 to 8 inches thick)
Bt2--10 to 17 inches; brown (7.5YR 4/4) very gravelly clay loam, dark reddish brown (5YR 3/4) moist; moderate medium prismatic structure parting to moderate medium subangular blocky; hard, friable, slightly sticky and slightly plastic; common fine and very fine roots; common fine and very fine pores; common moderately thick clay films on faces of peds and in pores; organic staining on faces of peds; 40 percent subangular to subrounded pebbles; neutral (pH 7.0); gradual wavy boundary. (5 to 8 inches thick)
2Bt3--17 to 22 inches; yellowish red (5YR 5/6) very gravelly clay, reddish brown (5YR 4/4) moist; strong medium subangular blocky structure; very hard, firm, sticky and plastic; few fine roots and pores; 30 percent subangular and subrounded pebbles and 15 percent subangular and subrounded cobbles; some cobbles are moderately weathered; common moderately thick clay films; neutral (pH 7.0); gradual wavy boundary. (4 to 7 inches thick)
2Btk1--22 to 30 inches; yellowish red and pinkish white (5YR 5/6) and (5YR 8/2) very gravelly clay loam, reddish brown and pinkish gray (5YR 5/4) and (5YR 7/2) moist; moderate medium and fine subangular blocky structure; very hard, firm, slightly sticky and slightly plastic; few fine and very fine roots and pores; common moderately thick clay films on faces of peds and in pores; 35 percent subangular and subrounded pebbles and 10 percent subangular and subrounded cobbles; cobbles have carbonate coating on underneath side; mildly alkaline (pH 7.5); clear wavy boundary. (4 to 9 inches thick)
2Btk2--30 to 36 inches; light yellowish brown (10YR 6/4) extremely gravelly sandy clay loam, dark brown (7.5YR 4/4) moist, crushed; mottled with pale yellow (5Y 8/3); moderate medium subangular blocky structure; very hard, friable, slightly sticky and slightly plastic; few fine roots; few fine and very fine pores; few thin clay films on some faces of peds and in pores; 50 percent subangular and subrounded pebbles, 20 percent subangular and subrounded cobbles; cobbles have carbonates coatings on underneath side; strongly calcareous in spots; mildly alkaline (pH 7.5); clear wavy boundary. (5 to 9 inches thick)
3Bk--36 to 48 inches; pinkish white (7.5YR 8/2) and brown (7.5YR 5/4) gravelly loam, pink (7.5YR 7/4) and brown (7.5YR 4/4) moist; moderate medium platy structure; slightly hard, slightly sticky and slightly plastic; few very fine roots; common fine tubular pores; 20 percent pebbles coated with carbonates; 70 percent of this horizon has segregated carbonates with colors of pinkish white when dry; strongly calcareous; moderately alkaline (pH 8.0); gradual wavy boundary. (0 to 14 inches thick)
3C--48 to 60 inches; brown (7.5YR 5/4) gravelly loam, brown (7.5YR 4/4) moist; massive; slightly hard, friable, slightly plastic; few very fine roots; few fine tubular pores; common carbonate fragments, pinkish white (7.5YR 8/2), pink (7.5YR 7/4) moist; carbonate coatings on bottoms of some rock fragments; 25 percent pebbles and 5 percent cobbles; strongly calcareous; moderately alkaline (pH 8.0).
TYPE LOCATION: Garfield County, Utah; Tom Best Spring Road; SW 1/4 sec. 22, T. 35 S., R. 4 W.
RANGE IN CHARACTERISTICS: The mollic epipedon ranges from 10 to 15 inches thick. Rock fragments range from 35 to 50 percent in the upper 20 inches of the Bt horizon. These soils have a mean annual soil temperature of about 44 to 47 degrees F. and a mean summer soil temperature at a depth of 20 inches of about 59 to 64 degrees F. The soils are dry in some part of the moisture control section for 60 to 75 percent of the time the soil temperature is above 41 degrees F. The soils are noncalcareous to depths of 12 to 30 inches and are strongly to very strongly calcareous below these depths.
The upper 10 to 15 inches have hue of 5YR to 10YR, value of 4 or 5 dry, 2 or 3 moist, and chroma of 2 or 3.
The Bt and Btk horizons have hue of 5YR to 10YR, value of 4 or 5 dry, 3 to 5 moist, and chroma of 2 to 6. Few mottles with hue of (5Y 8/3) and (5YR 8/2) occur in the lower part of the B horizon. The Bt horizon is very gravelly sandy clay loam, very gravelly clay and very cobbly clay and has 35 to 45 percent clay.
The Bk horizon ranges from very gravelly and cobbly loamy sand, gravelly loam and very cobbly clay loam. Some pedons have 5 to 15 percent stones throughout.
COMPETING SERIES: This is the Kolob series. Kolob soils are non-calcareous throughout.
GEOGRAPHIC SETTING: Showalter soils formed in a thick mantle of mixed volcanic alluvium on pediment surfaces. The relief is nearly level and undulating to steep. Elevations range from 7,400 to 8,400 feet. The average annual precipitation is 14 to 17 inches and the freeze-free period ranges from 70 to 95 days. The mean annual temperature is 42 to 45 degrees F. and the mean summer temperature is 59 to 64 degrees F.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Circleville, Guben and Panguitch soils. Circleville soils have bedrock at depths of 20 to 36 inches. Guben and Panguitch soils have cambic horizons with less than 35 percent clay.
DRAINAGE AND PERMEABILITY: Well-drained; medium runoff; slow permeability.
USE AND VEGETATION: Rangeland. Potential vegetation is mainly pinyon pine and Utah juniper with an understory of black sagebrush and blue grama.
DISTRIBUTION AND EXTENT: South-central part of Utah. This series is moderately extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Paunsaugunt Area, Utah, 1969.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - the zone from the surface of the soil to a depth of 10 inches (A, Bt1 horizons).
Argillic horizon - the zone from 5 to 36 inches (Bt1, Bt2, 2Bt, 2Btk1, 2Btk2).