Established Series


The Bauxson series consists of a thin mantle of soil material over fractured, displaced porcelanite. These soils are very deep and well drained. Bauxson soils occur on ridges, summits, and hillslopes associated with tablelands. They formed in residuum and colluvial slopewash derived from porcelanite beds. Slopes are both simple and complex and range from 3 to about 100 percent. The mean annual precipitation is about 16 inches, and the mean annual temperature is about 46 degrees F.

TAXONOMIC CLASS: Fine-loamy over fragmental, mixed, superactive, mesic Aridic Argiustolls

TYPICAL PEDON: Bauxson channery loam--rangeland. (Colors are for dry soil unless otherwise stated.)

A--0 to 2 inches; reddish gray (5YR 5/2) channery loam, dark reddish brown (5YR 3/3) moist; weak fine granular structure; soft, friable, slightly sticky and slightly plastic; 20 percent fine porcelanite channers; mildly alkaline (pH 7.4); clear smooth boundary. (1 to 4 inches thick)

Bt--2 to 13 inches; brown (7.5YR 5/2) clay loam, dark brown (7.5YR 3/2) moist; moderate coarse subangular blocky structure parting to moderate medium and fine subangular blocky; slightly hard, friable, sticky and plastic; common distinct clay films on faces of peds; 10 percent fine porcelanite channers; mildly alkaline (pH 7.8); gradual smooth boundary. (9 to 14 inches thick)

BC--13 to 18 inches; reddish brown (5YR 5/4) very channery clay loam, dark reddish brown (5YR 3/4) moist; very weak coarse subangular blocky structure parting to moderate very fine subangular blocky; soft, friable, sticky and plastic; 40 percent fine porcelanite channers; moderately alkaline (pH 8.0); clear smooth boundary. (0 to 7 inches thick)

2C--18 to 60 inches; fractured, displaced porcelanite; interstices are larger than 5 mm. and devoid of soil material; common, moderately thick coatings of secondary calcium carbonates on bottom side of fragments in the upper 20 inches.

TYPE LOCATION: Sheridan County, Wyoming; approximately 100 yards west of the Stout site; SE1/4, SE1/4, Sec. 27, T. 54 N., R. 82 W.

RANGE IN CHARACTERISTICS: Depth to the fragmental substratum ranges from 10 to 20 inches. Depth to the base of the argillic horizon is 10 inches or more. The mean annual soil temperature ranges from 47 to 52 degrees F. The soil mantle is typically noncalcareous to the contrasting fragmental material but may be calcareous immediately above the fragmental material in some pedons.

The A horizon has hue of 7.5YR through 2.5YR, value of 4 or 5 dry, 2 or 3 moist, and chroma of 2 or 3. Rock fragments range from 0 to 20 percent fine channers and 0 to 5 percent angular cobble. Reaction is neutral or mildly alkaline.

The Bt horizon has hue of 7.5YR through 2.5YR; value of 4 or 5 dry, 2 or 3 moist; and chroma of 2 or 3. It is typically clay loam or silty clay loam and more than 15 percent but less than 35 percent fine or coarser sand. Rock fragments are typically 10 percent or less but range from 0 to 15 percent fine porcelanite channers. Reaction is mildly or moderately alkaline.

The BC or C horizon has hue of 7.5YR through 2.5YR, value of 5 or 6 dry, 3 through 5 moist, and chroma of 2 though 4. Matrix texture is loam or clay loam with 18 to 35 percent clay. Rock fragments range from 45 to 75 percent fine porcelanite channers and 0 to 5 percent angular cobble.

The 2C horizon consists of red, yellowish red, and brown fractured porcelanite. Only a few interstices in the upper few inches are partially filled with soil material. The porcelanite has been displaced and fractured by the heat generated when coal seams burned. Clinkers are common in some strata. Carbonate coatings are common on coarse fragments in the upper part of this material but typically decrease with increasing depth.

COMPETING SERIES: This is the Wilaha series in the same family and the similar Harlan and Kirtley series. Wilaha soils formed in materials derived from pyroclastics and have substrata of cinders. Harlan and Kirtley soils do not have fragmental substrata. Also Kirtley soils have a paralithic contact at 20 to 40 inches.

GEOGRAPHIC SETTING: Bauxson soils are on ridge, summits, and hillslopes. These soils formed in residuum and colluvial slopewash derived from weathered porcelanite. Slopes are both complex and simple and range from 3 to 100 percent. Elevations range from 4,000 to 5,200 feet. The mean annual precipitation is about 16 inches at the type location but ranges from 15 to 19 inches. The mean annual temperature is about 47 degrees but ranges from 45 to 51 degrees F. The frost-free period is from 110 to 130 days depending upon aspect and elevation.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Baux, Shingle, Spearman and the competing Harlan and Kirtley soils. Baux soils occur intermixed with the Bauxson soils and do not have an argillic horizon. The Shingle and Spearmont soils occur on contiguous areas over clay shale. Both soils lack argillic horizons.

DRAINAGE AND PERMEABILITY: Well drained; slow to rapid runoff; moderate permeability in the fine soil material and very rapid in the fragmental material.

USE AND VEGETATION: Rangeland and wildlife habitat. Native vegetation consists of bluebunch wheatgrass, Idaho fescue, needleandthread, and some silver sagebrush.

DISTRIBUTION AND EXTENT: Northeastern and north central Wyoming. The series is of moderate extent.


SERIES ESTABLISHED: Sheridan County, Wyoming; 1987

REMARKS: Diagnostic horizons and features recognized in this pedon are:

Mollic epipedon - 0 to 13 inches (A,Bt)

Argillic horizon - 2 to 13 inches (Bt)

Lithiologic discontinuity - 18 to 60 inches..

SIR- WY0626

National Cooperative Soil Survey