LOCATION ARGIROCKER SD WYTentative Series
TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, frigid Lithic Argiustolls
TYPICAL PEDON: Argirocker silt loam, on a north facing, slightly convex backslope of 13 percent in a mixed ponderosa pine/short grass community at an elevation of about 1,219 meters. (Colors are for moist soil unless otherwise noted.) When described on September 1, 2005 the soil was dry throughout.
Oi--0 to 1.5 centimeters; slightly decomposed pine needles, cones, twigs, and herbaceous plant residue. (1 to 2.5 centimeters thick)
A--1.5 to 7 centimeters; black (10YR 2/1) silt loam, very dark brown (10YR 2/2) dry; weak fine subangular blocky structure parting to strong medium and fine granular; slightly hard, very friable, slightly sticky and slightly plastic; 10 percent subangular limestone gravel; many very fine, few fine roots throughout; many fine and few fine continuous pores; noneffervescent; neutral; abrupt smooth boundary. (5 to 10 centimeters thick)
Bt1--7 to 15 centimeters; 60 percent dark brown (7.5YR 3/2) and 40 percent dark reddish brown (5YR 3/3) cobbly silty clay loam, brown (7.5YR 4/3) and reddish brown (5YR 4/3) dry; moderate fine subangular blocky structure parting to moderate fine granular; hard, friable, slightly sticky and moderately plastic; few (15 percent) faint clay films on all faces of peds; 15 percent subangular limestone cobble and 10 percent subangular limestone gravel; many very fine, few medium and fine roots throughout; common very fine and few fine discontinuous pores; noneffervescent; neutral; clear wavy boundary.
Bt2--15 to 25 centimeters; dark reddish brown (5YR 3/3) extremely flaggy silty clay loam, reddish brown (5YR 4/3) dry; hard, friable, slightly sticky and slightly plastic; few (20 percent) faint clay films on all faces of peds; 60 percent angular and subangular limestone fragments, of which 20 percent are flagstones, 20 percent cobbles, 15 percent channers, and 5 percent stones; common medium and very fine, few fine roots, matted around and between rock fragments; few very fine discontinuous pores; soil matrix is noneffervescent, a thin layer surrounding most rock fragments is strongly to violently effervescent; slightly alkaline; abrupt wavy boundary. (Combined thickness of the Bt horizon is 10 to 20 centimeters)
R--25 to 203 centimeters; very strongly cemented or indurated, fractured limestone; distance between fractures is 35 to greater than 50 centimeters.
TYPE LOCATION: Lawrence County, South Dakota; along the southwest edge of the Boulder Park subdivision; located in the SE1/4, SE1/4, SE1/4 of sec. 15, T. 5 N., R. 4 E.; Sturgis USGS quad; 44 degrees 23 minutes 18.1 seconds N. latitude and 103 degrees 36 minutes 37.0 seconds W. longitude; NAD 1983
RANGE IN CHARACTERISTICS:
Soil moisture: Argirocker soils are dry in some or all parts of the moisture control section for 90 cumulative days in 9 years out of 10 when the soil temperature at the lithic contact is 5 degrees C. or higher. It is moist in some or all parts from the period between the spring and summer solstice, and for 60 consecutive days or more within the 4 months following the summer solstice, in 6 or more years out of 10. An ustic soil moisture regime bordering on udic.
Mean annual soil temperature: 6.5 to 9 degrees C
Mean summer soil temperature: 12 to 15 degrees C
Thickness of the mollic epipedon: 18 to 30 centimeters (when mixed); includes all the A horizon and part or all of the argillic horizon
Depth to lithic contact: 15 to 50 centimeters to hard limestone
Depth to argillic horizon: 5 to 10 centimeters
Particle-size control section (weighted average):
Clay content: 20 to 35 percent
Sand content: less than 15 percent fine and coarser material
Rock fragments: 35 to 65 percent very strongly cemented to indurated limestone fragments, of which 10 to 30 percent are gravel and/or channers, 10 to 30 percent cobble, 0 to 10 percent stones, and 10 to 25 percent flagstones.
A horizon:
Hue: 10YR
Value: 2 or 3 moist, 2 to 4 dry
Chroma: 1 or 2
Texture: SIL, CB-SIL, CBV-SIL
Clay content: 15 to 27 percent
Rock fragments: 5 to 40 percent very strongly cemented or indurated limestone fragments (0 to 10 percent gravel and 5 to 30 percent cobble)
Reaction: neutral or slightly alkaline (pH 6.6 to 7.8)
Bt horizon:
Hue: 5YR to 10YR
Value: 3 or 4 moist, 4 or 5 dry
Chroma: 2 to 4
Texture: CB-SICL, CBV-SICL, GRV-SICL, FLX-SICL, CBV-SIL, FLV-SIL
Clay content: 20 to 35 percent
Rock fragments: 35 to 65 percent horizon average (some subhorizons may have less)
Reaction: neutral or slightly alkaline (pH 6.6 to 7.8)
Btk (and/or Bk) horizon, when present (in 40 to 50 percent of pedons):
Hue: 5YR to 10YR
Value: 4 or 5 moist, 5 to 7 dry
Chroma: 2 to 4
Texture: CB-SICL, CBV-SICL, FLX-SICL, CBV-SIL, FLV-SIL
Clay content: 20 to 30 percent
Rock fragments: 35 to 70 percent
Calcium carbonate equivalent: 2 to 15 percent
Reaction: slightly alkaline or moderately alkaline (pH 7.4 to 8.4)
R horizon:
Hue: 7.5YR or 10YR
Value: 5 to 7 moist, 6 to 8 dry
Chroma: 1 to 3
Texture: unweathered bedrock; very strongly cemented or indurated, fractured limestone; horizontal distance between fractures is typically greater than 30 centimeters and generally increases with depth, and the vertical distance ranges from 15 to 60 centimeters or more.
COMPETING SERIES:
Bushvalley - formed in material derived from breccia, tuff, ash, cinders, or igneous rock
Gnojek - occur over fine-grained sandstone or fine-grained igneous rock
Owlrock - occur at higher elevations, are more moist from late fall to spring, and are driest in
May and June
Teaspoon - formed in residuum from gneiss and/or igneous rock
Tolbert - have thicker A horizons and formed in material derived from fine-grained sandstone, fine-grained igneous rock, or interbedded sandstone and shale
Tolman - formed in residuum from hard noncalcareous sandstone
Zibetod - occur at higher elevations, are more moist from late fall to spring, and are driest in May and June
GEOGRAPHIC SETTING:
Parent material: Residuum or local slope alluvium over residuum, derived primarily from hard limestone of the Minnekahta formation; also occurs in some places over hard limestone of the Madison formation.
Landform: Backslopes of ridges and dipslopes in mountains
Slopes: 2 to 40 percent
Elevation: 1,158 to 1,523 meters
Mean annual air temperature: 7 to 9 degrees C
Mean annual precipitation: 508 to 635 millimeters
Precipitation pattern: In most years, half or more of the normal precipitation falls as rain and/or snow in the spring and early summer
Frost-free period: 100 to 140 days.
GEOGRAPHICALLY ASSOCIATED SOILS:
Citadel - are very deep, fine textured, and lack mollic epipedons; on concave positions generally below Argirocker soils
Rockerville - do not have argillic horizons; on similar landscape positions
Sawdust - are deep or very deep; generally on backslopes below Argirocker soils
Vanocker - are deep or very deep; generally on shoulders and backslopes below Argirocker soils
DRAINAGE AND PERMEABILITY: Well drained; slow to rapid runoff, depending on slope; moderate to moderately rapid permeability.
USE AND VEGETATION: Argirocker soils are typically sparsely to moderately wooded and utilized for livestock grazing, wildlife habitat, and limited timber production. The native vegetation consists of an overstory of ponderosa pine and bur oak; understory species include porcupine grass, slender wheatgrass, various bluegrasses, Oregon grape, and common juniper.
DISTRIBUTION AND EXTENT: Argirocker soils occur on the low limestone plateau physiographic area of the Black Hills of South Dakota and possibly Wyoming; LRR G, MLRA 62; the series is of small extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Denver, Colorado
SERIES PROPOSED: Lawrence County, South Dakota, 2006. The name is a derivative of the geographically-associated Rockerville series.
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Series control section: The zone from 1.5 to 25 centimeters.
Particle-size control section (argillic horizon): The zone from 7 to 25 centimeters. (Bt1 and Bt2 horizons)
Mollic epipedon: The zone from 1.5 to 25 centimeters. (A, Bt1, and Bt2 horizons)
Lithic contact: The contact with hard limestone at 25 centimeters. (R horizon)
The assignment of the cation-exchange activity class is inferred from lab data from similar soils in the surrounding area.
Taxonomic Version: Keys to Soil Taxonomy, Ninth Ed., 2003
ADDITIONAL DATA: None at present