LOCATION ROUBAIX SD

Established Series
JWW
01/2014

ROUBAIX SERIES

The Roubaix series consists of very deep, well drained soils that formed in alluvium and residuum derived from mixed igneous and sedimentary rocks. Roubaix soils are on ridges, terraces and hillslopes. Slopes range from 0 to 40 percent. Mean annual precipitation is about 610 mm and the mean annual temperature is about 7 degrees C.

TAXONOMIC CLASS: Clayey-skeletal, mixed, superactive, frigid Haplic Glossudalfs

TYPICAL PEDON: Roubaix loam, on an northeast facing, slightly convex slope of 3 percent, in a coniferous woodland community at an elevation of 1680 meters. (Colors are for moist soil unless otherwise noted.) When described on July 8, 2004 the soil was moist throughout.

Oi--0 to 2 cm; slightly decomposed pine needles, twigs, and bark. (0 to 5 cm thick)

AE--2 to 13 cm; very dark grayish brown (10YR 3/2) silt loam, dark grayish brown (10YR 4/2) dry; moderate fine granular structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine and fine roots; many very fine highly continuous tubular pores; about 2 percent subrounded gravel from mixed sources; moderately acid; clear smooth boundary. (0 to 10 cm thick)

E--13 to 25 cm; brown (10YR 5/3) gravelly silt loam, light gray (10YR 7/2) dry; moderate fine and medium subangular blocky structure; slightly hard, very friable, slightly sticky and slightly plastic; common very fine, fine, and medium roots; common very fine and fine and few medium highly continuous tubular pores; about 20 percent subrounded and rounded gravel from mixed sources; moderately acid; clear wavy boundary. (5 to 18 cm thick)

Bt/E--25 to 36 cm; 60 percent brown (7.5YR 4/3) gravelly clay loam, brown (7.5YR 5/4) dry (Bt part), and 40 percent brown (10YR 5/3) gravelly silt loam, light gray (10YR 7/2) dry (E part); moderate fine and medium angular blocky structure; hard, firm, moderately sticky and moderately plastic; few very fine and fine roots; common very fine and fine highly continuous tubular pores; about 15 percent faint patchy brown (7.5YR 4/3) clay films on all faces of peds (Bt part); about 25 percent subrounded gravel from mixed sources; strongly acid; clear wavy boundary. (7 to 23 cm thick)

Bt1--36 to 64 cm; dark brown (7.5YR 3/4) very gravelly clay loam, brown (7.5YR 5/4) dry; strong fine and medium angular blocky structure; hard, firm, moderately sticky and very plastic; few very fine and fine roots; many very fine, common fine highly continuous tubular pores; about 70 percent distinct continuous dark brown (7.5YR 3/3) moist clay films on all faces of peds; about 45 percent subrounded and rounded gravel from mixed sources; strongly acid; clear wavy boundary.

Bt2--64 to 81 cm; brown (7.5YR 4/4) very gravelly clay loam, brown (7.5YR 5/4) dry; strong fine and medium angular blocky structure; hard, firm, moderately sticky and moderately plastic; few very fine and fine roots; many very fine, common fine highly continuous tubular pores; about 40 percent distinct continuous dark brown (7.5YR 3/4) and strong brown (7.5YR 4/6) moist clay films on all faces of peds; about 45 percent subrounded and rounded gravel from mixed sources; strongly acid; gradual wavy boundary. (Combined Bt horizons 38 to 61 cm thick)

2BC--81 to 140 cm; brown (7.5YR 5/4) very gravelly sandy loam, light brown (7.5YR 6/4) dry; weak medium subangular blocky structure; slightly hard, very friable, nonsticky and nonplastic; few very fine and fine roots; many very fine, common fine moderately continuous tubular pores; about 50 percent subrounded gravel from mixed sources; strongly acid; gradual wavy boundary. (45 to 76 cm thick)

2C--140 to 200 cm; brown (7.5YR 5/4) very gravelly loam, light brown (7.5YR 6/4) dry; massive; slightly hard, friable, slightly sticky and slightly plastic; few very fine, fine, and medium roots; many very fine, common fine moderately continuous tubular pores; about 50 percent subrounded gravel from mixed sources; strongly acid. (0 to 64 cm thick)

TYPE LOCATION: Lawrence County, South Dakota; about 2 miles north of Roubaix townsite along Forest Service road 180; located about 230 feet east and 820 feet south of the northwest corner of Sec. 21, T. 4 N., R. 4 E.; Deadwood South USGS quad; 44 degrees 17 minutes 52.3 seconds N. latitude and 103 degrees 39 minutes 13.2 seconds W. longitude; NAD 83.

RANGE IN CHARACTERISTICS:

Particle-size control section (weighted average):
Clay content: 35 to 40 percent
Sand content: 15 to 30 percent
Rock fragments: 35 to 50 percent subrounded and/or rounded rock fragments from mixed igneous, metamorphic, and sedimentary sources; 25 to 40 percent gravel and 5 to 20 percent cobbles

An Oi or Oe horizon occurs in most pedons.

AE horizon:
Hue: 10YR
Value: 3 or 4, 4 or 5 dry
Chroma: 2 or 3
Texture: L, SIL, (fine-earth fraction)
Clay content: 12 to 18 percent
Rock fragments: 2 to 20 percent gravel
Reaction: Medium acid

An A horizon occurs above the AE in some pedons.

E horizon:
Hue: 10YR
Value: 4 or 5, 6 or 7 dry
Chroma: 2 or 3, 2 dry
Texture: L, SIL (fine-earth fraction)
Clay content: 10 to 16 percent
Rock fragments: 10 to 35 percent gravel, 0 to 5 percent cobble
Reaction: Medium acid

The Bt/E horizon has properties similar to those of its respective parts. This horizon is typically 60 to 80 percent Bt horizon and 20 to 40 percent E horizon. Some pedons have an E/B horizon above the Bt/E.

Bt horizon:
Hue: 7.5YR or 10YR
Value: 3 or 4,4 or 5 dry
Chroma: 3 to 6
Texture: CL (fine-earth fraction)
Clay content: 35 to 40 percent weighted average; lower subhorizons may have as low as 30 percent
Rock fragments: 35 to 50 percent
Reaction: Strongly acid

2BC and 2C horizons:
Hue: 7.5YR or 10YR
Value: 4 or 5, 5 or 6 dry
Chroma: 3 to 6
Texture: SL,L (fine-earth fraction)
Clay content: 12 to 25 percent
Rock fragments: 40 to 55 percent, of which 30 to 45 percent are gravel and 0 to 20 percent cobble
Reaction: Strongly acid

COMPETING SERIES: There are no competing series in this taxonomic class.

GEOGRAPHIC SETTING:
Parent material: Alluvium or residuum derived from mixed igneous, metamorphic, and sedimentary sources
Landform: Mountain ridges, terraces, and hillslopes
Slopes: 0 to 40 percent
Elevation: 1370 to 1830 meters
Mean annual air temperature: 5 to 8 degrees C
Mean annual precipitation: 510 to 715 mm
Precipitation pattern: In most years, half or more of the annual precipitation occurs as snow and rain from March through July.
Frost-free period: 80 to 120 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Bluelead(T), Citadel, Pactola, Tollflat(T), Vanocker, and Virkula series. Bluelead soils have mollic epipedons, are loamy-skeletal, and formed in alluvium and colluvium from sedimentary rocks. They are on similar landscape positions. Citadel and Tollflat soils are fine, contain less than 35 percent coarse fragments in the control section, and formed in material derived from sedimentary rocks. They are on similar landforms on linear and concave surfaces. Pactola soils are loamy-skeletal and formed in material derived primarily from schist. They are on similar landforms. Vanocker soils are loamy-skeletal and formed in colluvium and residuum derived from limestone. They are on similar landform positions. Virkula soils are fine-silty and contain less than 35 percent coarse fragments in the control section. They are on similar landforms and are more commonly found on linear and concave surfaces.

DRAINAGE AND SATURATED HYDRAULIC CONDUCTIVITY: Well drained. Moderately high to moderately low saturated hydraulic conductivity.

USE AND VEGETATION: Roubaix soils are used for timber production, wildlife habitat, recreation, and livestock grazing. Native vegetation consists of an overstory of ponderosa pine and bur oak; understory species consist of timothy, Oregon grape, and common juniper.

DISTRIBUTION AND EXTENT: Roubaix soils occur in the Black Hills of South Dakota; LRR G, MLRA 62. The series is of small extent.

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

SERIES ESTABLISHED: Update Soil Survey of Lawrence County, South Dakota, 2009. The name is taken from a townsite near the type location.

REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Particle-size control section: The zone from 25 to 75 cm. (Bt/E, Bt1, and Bt2 horizons)
Ochric epipedon: The zone from 2 to 13 cm. (AE horizon)
Albic horizon: The zone from 13 to 25 cm. (E horizon)
Glossic horizon: The zone from 25 to 36 cm. (Bt/E horizon)
Lithologic discontinuity: At the upper boundary of the 2BC horizon.

Additional Remarks: The Roubaix series occurs on Tertiary-aged White River geologic formations in the Black Hills. It may have been mapped as Hilger in complex with Virkula in the Soil Survey of Custer-Pennington Counties, Black Hills Parts.

Taxonomic Version: Keys to Soil Taxonomy, Eleventh Ed., 2010

ADDITIONAL DATA:

National Cooperative Soil Survey
U.S.A.