LOCATION MILLPOT WYTentative Series
TAXONOMIC CLASS: Coarse-loamy, carbonatic Ustic Calcicryolls
TYPICAL PEDON: Millpot gravelly sandy loam, rangeland. (Colors are for dry soil unless otherwise stated.)
A11--0 to 3 inches; brown (7.5YR 5/2) gravelly sandy loam, dark brown (7.5YR 3/2) moist; moderate fine granular structure; soft, very friable; many very fine and fine roots; calcareous; mildly alkaline (pH 7.8); clear wavy boundary. (2 to 5 inches thick)
A12--3 to 14 inches; brown (7.5YR 5/2) gravelly sandy loam, dark brown (7.5YR 3/2) moist; weak coarse and very fine subangular blocky structure; soft, very friable; many very fine and fine roots; calcareous; mildly alkaline (pH 7.8); clear wavy boundary. (5 to 12 inches thick)
Clca--14 to 42 inches; Pinkish white (7.5YR 8/2) gravelly sandy loam, pinkish gray (7.5YR 6/3) moist; massive; soft, very friable; few very fine and fine roots; calcareous, secondary lime mainly disseminated; moderately alkaline (pH 8.0); gradual wavy boundary. (20 to 30 inches thick)
C2ca--42 to 55 inches; Light yellowish brown (10YR 6/4) gravelly sandy loam, yellowish brown (10YR 5/4) moist; massive; soft, very friable; calcareous, secondary lime mainly disseminated; moderately alkaline (pH 8.0).
TYPE LOCATION: Sweetwater County, Wyoming; approximately 3,700 feet south of the NE corner of Sec. 19, T14N, R104W.
RANGE IN CHARACTERISTICS: The soils are typically calcareous throughout, but some pedons may be leached a few inches. The mean annual soil temperature is about 40 degrees to 44 degrees F. The mean summer soil temperature is about 53 degrees to 59 degrees F. The control section is gravelly sandy loam or gravelly loam and averages between 10 and 18 percent clay. Gravel ranges from 15 to 35 percent.
The A horizon has hue of 10YR or 7.5YR; value of 4 or 5 dry, 2 or 3 moist; and chroma of 2 or 3. It is mildly or moderately alkaline.
The Cca horizon has hue of 10YR or 7.5YR. It averages between 40 and 60 percent calcium carbonate equivalent that decreases by more than 5 percent in a lower horizon. This horizon is moderately or strongly alkaline.
COMPETING SERIES: There are no series listed in this subgroup and family. The Ard (T) series is in the same subgroup but has 15 to 30 percent calcium carbonate equivalent below the mollic epipedon. The Feltonia (T) series is closely related but has a mollic epipedon more than 16 inches thick and has less than 40 percent calcium carbonate equivalent in the control section.
GEOGRAPHIC SETTING: Millpot soils are on nearly level to strongly sloping fans and fan piedmonts. Slopes are 1 to 15 percent. They formed in very strongly calcareous alluvium. Elevation is 7,200 to 8,600 feet. The mean annual precipitation is 13 to 17 inches. The mean annual air temperature is 38 degrees to 42 degrees F. The frost-free season is 60 to 90 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Leavitt and Feltonia soils. Leavitt soils have an argillic horizon and are in the "mixed" family. Feltonia soils have a mollic epipedon more than 16 inches thick.
DRAINAGE AND PERMEABILITY: Well drained; slow runoff; moderately rapid permeability.
USE AND VEGETATION: These soils are used for range. Native vegetation is black sagebrush, western wheatgrass, and threadleaf sedge.
DISTRIBUTION AND EXTENT: In the mountains of southern Wyoming. The series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES PROPOSED: Sweetwater County, Wyoming, south part; 1976. The name is coined from the Miller-Potter Mountain area.
OSED scanned by NSSQA. Last revised by state on 4/76.