LOCATION GILLUM                  SD+WY

Established Series
WTS/DJB/JWW
01/2014

GILLUM SERIES

The Gillum series consists of deep and very deep, well drained soils formed in slope alluvium and residuum weathered from limestone and calcareous sandstone. Gillum soils are on backslopes and footslopes of hillslopes in mountains. Slopes range from 2 to 15 percent. The mean annual precipitation is about 762 mm, and the mean annual air temperature is about 5 degrees C.

TAXONOMIC CLASS: Fine, mixed, superactive Calcic Argicryolls

TYPICAL PEDON: Gillum silt loam, on a south-southeast facing, linear slope of 9 percent, in grassland, at an elevation of 1,950 meters. When described on September 23, 2008, the soil was dry to 24 cm and slightly moist below. (Colors are for moist soil unless otherwise noted.)

A1--0 to 8 cm; very dark brown (10YR 2/2) silt loam, dark grayish brown (10YR 4/2) dry; weak fine and medium granular structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine and many fine roots throughout; moderately acid; abrupt smooth boundary.

A2--8 to 24 cm; very dark brown (10YR 2/2) silt loam, grayish brown (10YR 5/2) dry; weak fine subangular blocky structure parting to moderate fine and medium granular; moderately hard, very friable, slightly sticky and slightly plastic; common very fine and fine roots throughout; moderately acid; clear wavy boundary. (Thickness of the A horizon is 13 to 30 cm)

BA--24 to 37 cm; brown (10YR 4/3) silty clay loam, brown (10YR 5/3) and yellowish brown (10YR 5/4) dry; moderate fine and medium angular blocky structure; slightly hard, very friable, slightly sticky and moderately plastic; common very fine and few fine roots throughout; slightly acid; clear wavy boundary. (0 to 16 cm thick)

Bt1--37 to 55 cm; about 50 percent brown (10YR 4/3) and 50 percent brown (10YR 5/3) silty clay, yellowish brown (10YR 5/4) and light yellowish brown (10YR 6/4) dry; weak medium prismatic structure parting to strong fine and medium angular blocky; moderately hard, firm, sticky and very plastic; few very fine and fine roots throughout; about 60 percent, faint, brown (10YR 4/3) clay films on vertical faces of peds; slightly acid; clear wavy boundary.

Bt2--55 to 64 cm; about 50 percent dark brown (10YR 3/3) and brown (10YR 4/3) silty clay, brown (10YR 4/3) and brown (10YR 5/3) dry; strong medium and coarse subangular blocky structure; hard, friable, moderately sticky and plastic; few very fine roots throughout; about 50 percent faint brown (10YR 4/3) and dark brown (10YR 3/3) clay films on vertical faces of peds; about 5 percent medium prominent very pale brown (10YR 8/3) weakly cemented carbonate nodules; neutral; clear smooth boundary. (Thickness of the Bt horizon is 23 to 48 cm)

Btk--64 to 91 cm; light olive brown (2.5Y 5/4) gravelly silty clay loam, light yellowish brown (2.5Y 6/4) dry; moderate medium and coarse subangular blocky structure; very hard, firm, slightly sticky and moderately plastic; few very fine roots throughout; about 10 percent faint light olive brown (2.5Y 5/4) clay films on all faces of peds; about 3 percent medium, prominent very pale brown (10YR 8/3) carbonate masses and 10 percent medium, prominent very pale brown (10YR 8/3) weakly cemented calcium carbonate nodules; about 25 percent angular and 5 percent subangular limestone gravel; slightly effervescent; slightly alkaline; clear wavy boundary. (15 to 76 cm thick)

Bk1--91 to 108 cm; light olive brown (2.5Y 5/4) gravelly silty clay loam, light yellowish brown (2.5Y 6/4) dry; moderate fine and medium subangular blocky structure; moderately hard, friable, slightly sticky and slightly plastic; few very fine roots throughout; about 8 percent fine, prominent very pale brown (10YR 8/2) calcium carbonate threads throughout and 5 percent medium, prominent very pale brown (10YR 8/2) weakly cemented calcium carbonate nodules; about 25 percent angular and 5 percent subangular limestone gravel; strongly effervescent; moderately alkaline; clear wavy boundary.

Bk2--108 to 140 cm; light olive brown (2.5Y 5/4) very gravelly silty clay loam, light yellowish brown (2.5Y 6/4) dry; weak medium subangular blocky structure parting to moderate medium plate-like rock structure; hard, firm, slightly sticky and slightly plastic; few very fine roots around rock fragments; about 10 percent fine, prominent white (10YR 8/1) calcium carbonate threads throughout and 2 percent medium, prominent very pale brown (10YR 8/2) weakly cemented calcium carbonate nodules; about 35 percent angular and 5 percent subangular limestone gravel; strongly effervescent; moderately alkaline; gradual wavy boundary. (Thickness of the Bk horizon is 38 to 60 cm or more)

BCk--140 to 178 cm; light olive brown (2.5Y 5/4) very gravelly silty clay loam, light yellowish brown (2.5Y 6/4) dry; weak medium and coarse subangular blocky structure parting to weak thick plate-like rock structure; hard, firm, slightly sticky and slightly plastic; very few very fine roots around rock fragments; about 3 percent fine, prominent white (10YR 8/1), calcium carbonate threads; about 35 percent angular and subangular limestone gravel and 5 percent cobbles; strongly effervescent; moderately alkaline; gradual wavy boundary. (0 to 38 cm thick)

2C--178 to 200 cm; yellowish brown (10YR 5/4) gravelly clay loam, very pale brown (10YR 7/4) dry; weak thin and medium plate-like rock structure; slightly hard, friable, slightly sticky and slightly plastic; very few very fine roots around rock fragments; about 1 percent fine and medium, distinct very pale brown (10YR 8/2), weakly cemented calcium carbonate nodules; about 15 percent angular limestone gravel; strongly effervescent; moderately alkaline. (0 to 30 cm thick)

TYPE LOCATION: Lawrence County, South Dakota; east side of Besant Park, about 2,065 feet south and 2,450 feet west of the northeast corner of Sec. 27, T. 3 N., R. 2 E.; Nahant, S. Dak. USGS topographic quadrangle; 44 degrees 11 minutes 34.6 seconds N. latitude and 103 degrees 51 minutes 53.3 seconds W longitude; NAD 83.

RANGE IN CHARACTERISTICS:
Depth to calcium carbonate: 46 to 102 cm

A horizon:
Hue: 10YR
Value: 2 or 3, 4 or 5 dry
Chroma: 1 or 2
Texture: SIL, L
Reaction: slightly acid to strongly acid

BA or AB horizons occur in some pedons

Bt horizon:
Hue: 2.5YR to 10YR
Value: 3 to 5, 4 to 6 dry
Chroma: 2 to 4
Texture: SICL, CL, SIC, or C
Clay content: 35 to 55 percent
Reaction: slightly acid or neutral

Btk horizon:
Hue: 5YR to 10YR
Value: 4 to 6, 5 to 7 dry
Chroma: 3 or 4
Texture: SICL, CL, SIC, C
Clay content: 30 to 50 percent
Rock Fragments: 0 to 20 percent sandstone or limestone gravel
Reaction: slightly alkaline or moderately alkaline

Bk horizon:
Hue: 7.5YR to 2.5Y
Value: 4 to 6, 5 to 7 dry
Chroma: 3 or 4
Texture: SICL, CL, SIC, C
Clay content: 30 to 45 percent
Rock fragments: 5 to 35 percent limestone gravel and 0 to 10 percent cobble
Reaction: slightly alkaline or moderately alkaline

BCk and C horizons:
Hue: 7.5YR to 2.5Y
Value: 4 to 6, 5 to 7 dry
Chroma: 3 or 4
Texture: SICL, CL, L, SIL
Clay content: 25 to 40 percent
Rock fragments: 5 to 35 percent limestone gravel and 0 to 10 percent cobble
Reaction: slightly alkaline or moderately alkaline

A Cr horizon occurs in some pedons below 100 cm

COMPETING SERIES: There are no competing series.

GEOGRAPHIC SETTING:
Parent material: local alluvium and/or residuum derived from sedimentary rock, typically of the Minnelusa or Madison formations
Landform: Backslopes of and footslopes on hillslopes in Valleys; typically on linear or slightly concave surfaces
Slopes: 2 to 15 percent
Elevation: 1,890 to 2,135 meters
Mean annual air temperature: 2 to 6 degrees C
Mean annual precipitation: 660 to 865 millimeters
Precipitation pattern: In most years, half or more of the normal precipitation falls as rain and snow from March through mid-July.
Frost-free period: less than 90 days; frost can occur in any month in about 2 years out of 10.

GEOGRAPHICALLY ASSOCIATED SOILS:
Jenksdraw(T) - are moderately deep to hard bedrock; generally they occur on higher slopes
Redbird - are loamy-skeletal; they occur on similar or slightly lower footslope
Rockerville(T) - are shallow to hard bedrock; generally they occur on convex positions above Gillum soils

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained; slow to rapid runoff; moderately low saturated hydraulic conductivity.

USE AND VEGETATION: Gillum soils appear to have formed under a rotating forest/grassland complex. They are utilized for livestock grazing, wildlife habitat, and limited hay production. The modern perennial plant community includes Timothy, western wheatgrass, Kentucky bluegrass, bearded wheatgrass, prairie smoke, common yarrow, Rocky Mountain iris, Black-eyed Susan, red clover, shrubby cinquefoil.

DISTRIBUTION AND EXTENT: Gillum soils occur in the High Limestone Plateau physiographic area of MLRA 62 (the Black Hills) of South Dakota and Wyoming; LRR G; the series is of small extent.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado

SERIES PROPOSED: Lawrence County, South Dakota, 01/2002. The name is from Gillum Spring.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Soil moisture: Typic Udic
Mollic epipedon: Zone from 0 to 24 cm (A1 and A2 horizons)
Argillic horizon: Zone from 37 to 91 cm (Bt1, Bt2 and Btk horizons)
Secondary carbonates: Zone from 64 to 178 cm (Btk, Bk1, Bk2, and BCk horizons)

Taxonomic Version: Keys to Soil Taxonomy, Eleventh Edition, 2010

ADDITIONAL DATA:

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National Cooperative Soil Survey
U.S.A.