LOCATION WHITMORE AZInactive Series
TAXONOMIC CLASS: Loamy-skeletal, carbonatic, thermic, shallow Typic Petrocalcids
TYPICAL PEDON: Whitmore extremely gravelly loam - rangeland, recreation and wildlife habitat. (Colors are for dry soil unless otherwise noted.) The soil surface is partially covered with 50 percent limestone gravel, 10 percent cobble and 5 percent stone.
A1--0 to 1 inch; brown (10YR 5/3) extremely gravelly loam; dark brown (10YR 3/3) moist; weak fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; many very fine and fine and common medium roots; many very fine tubular pores; 50 percent gravel, 10 percent cobble and 5 percent stone; violently effervescent; moderately alkaline (pH 8.4); abrupt smooth boundary. (1 to 3 inches thick)
A2--1 to 3 inches; brown (10YR 5/4) very gravelly loam; brown (10YR 4/4) moist; weak fine subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; many very fine and fine and common medium roots; many very fine and fine tubular pores; 40 percent gravel, 5 percent cobble; violently effervescent; moderately alkaline (pH 8.4); abrupt wavy boundary. (2 to 7 inches thick)
Bkm--3 to 24 inches; pinkish gray (10YR 7/2) very gravelly calcium carbonate cemented lenses with indurated laminar cap; extremely hard; clear wavy boundary. (15 to 26 inches thick)
Bk--24 to 60 inches; pinkish gray (10YR 7/2) very gravelly sandy loam; light brown (10YR 6/3) moist; massive; slightly hard, very friable, slightly sticky and slightly plastic; few fine and medium roots; few fine tubular pores; many thick coats of calcium carbonate on underside of coarse fragments; violently effervescent; 50 percent gravel; moderately alkaline (pH 8.4).
TYPE LOCATION: Mohave County, Arizona; Lake Mead National Recreation Area; 2,500 feet north and 750 feet east of the southwest corner sec. 6, T. 32 N., R. 8 W.; 36 degrees, 12 minutes, 5 seconds north latitude and 113 degrees, 11 minutes, 55 seconds west longitude, NAD 27.
RANGE IN CHARACTERISTICS:
Soil moisture - Usually dry, moist for short periods during the winter months and spring and periodically in the upper part of the moisture control section for 10 to 20 days cumulative from July through September following summer convection storms. Driest May and June. Typic aridic soil moisture regime.
Soil temperature: 59 to 65 degrees F.
Depth to petrocalcic horizon: 3 to 10 inches
Clay content: 10 to 15 percent
Rock fragments: averages 40 to 50 percent
Calcium carbonate equivalence: 40 to 50 percent by weight in the less than 20 millimeter fraction
Some pedons may have a thin Bw or Bk horizon above the petrocalcic horizon.
A horizon - Hue: 7.5YR, 10YR
Value: 5 or 6 dry, 3 or 4 moist
Chroma: 3 through 6, dry or moist
Other features: Some pedons may contain pan fragments.
Bkm horizon - Cementation: indurated in the upper part or is continuously very strongly cemented with a laminar cap
COMPETING SERIES: There are no other competing series.
GEOGRAPHIC SETTING: Whitmore soils are on summits and side slopes of ballenas and fan terraces. These soils formed in alluvium derived primarily from limestone of the Kaibab Formation. Slopes are 2 to 50 percent. Elevations are 3,400 to 4,900 feet. The climate is arid with hot summers and mild winters. The mean annual precipitation is between 9 and 12 inches; mean annual air temperature is 57 to 63 degrees F.; and the frost-free season is about 180 to 240 days.
GEOGRAPHICALLY ASSOCIATED SOILS: This is the nearby Splanod soils. Splanod soils are less than 20 inches deep to hard sandstone bedrock.
DRAINAGE AND PERMEABILITY: Well drained. Medium to high runoff; moderately rapid permeability above the petrocalcic horizon.
USE AND VEGETATION: Rangeland and wildlife habitat. The present vegetation is mainly blackbrush, creosotebush, big galleta, green ephedra and banana yucca.
DISTRIBUTION AND EXTENT: Northwestern Arizona; MLRA is 30. Whitmore soils are not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Davis, California
SERIES PROPOSED: Mohave County, Arizona, soil survey of Lake Mead National Recreation Area, 1997.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from 0 to 3 inches (A1 and A2 horizons).
Petrocalcic horizon - The zone from about 3 to 24 inches (Bkm horizon).