LOCATION FALSEBOTTOM SD+WYTentative Series
TAXONOMIC CLASS: Sandy-skeletal, mixed, frigid Mollic Udifluvents
TYPICAL PEDON: Falsebottom very gravelly loam, on a northwest facing, linear slope of 7 percent in mixed deciduous, coniferous, and herbaceous plant community at an elevation of 1,417 meters. (Colors are for moist soil unless otherwise noted.) When described on August 8, 2005 the soil was dry in the surface and slightly moist from 13 to 152 centimeters.
A--0 to 13 centimeters; very dark grayish brown (10YR 3/2) very gravelly loam, dark grayish brown (10YR 4/2) dry; weak fine and very fine granular structure; soft, very friable, nonsticky and nonplastic; about 20 percent medium and coarse rounded gravel, 15 percent fine rounded gravel, and 5 percent rounded cobble; many fine and very fine, common medium roots; noneffervescent; slightly acid; clear smooth boundary. (10 to 22 centimeters thick)
AC--13 to 48 centimeters; dark brown (10YR 3/3) very gravelly coarse sand, brown (10YR 5/3) dry; single grain structure; loose, loose, nonsticky and nonplastic; about 45 percent coarse, medium, and fine rounded gravel, and 15 percent rounded cobble; common fine and very fine, few medium roots; noneffervescent; slightly acid; gradual wavy boundary. (0 to 40 centimeters thick)
C1--48 to 107 centimeters; brown (10YR 4/3) extremely gravelly coarse sand, stratified with thin layers of extremely gravelly fine sand and extremely gravelly fine sandy loam, brown (10YR 5/3) dry; single grain structure; loose, loose, nonsticky and nonplastic; about 50 percent coarse, medium, and fine rounded gravel, and 20 percent rounded cobble; few medium, fine, and very fine roots; noneffervescent; slightly acid; gradual wavy boundary.
C2--107 to 152 centimeters; brown (10YR 5/3) extremely gravelly coarse sand, stratified with thin layers of extremely cobbly fine sand and extremely gravelly fine sandy loam, pale brown (10YR 6/3) dry; massive structure parting to single grain; loose, loose, nonsticky and nonplastic; about 30 percent medium and 25 percent fine and very fine rounded gravel, and 25 percent rounded cobble; few medium, fine, and very fine roots; noneffervescent; slightly acid. (Combined thickness of the C horizon is 98 to 142 centimeters)
TYPE LOCATION: Lawrence County, South Dakota; about 2 miles north of Maitland townsite; located about 716 meters east and 783 meters north of the southwest corner of sec. 12, T. 5 N., R. 2 E.; Spearfish USGS quad; 44 degrees 24 minutes 34.5 seconds N. latitude and 103 degrees 49 minutes 13.9 seconds W. longitude; NAD 1983
RANGE IN CHARACTERISTICS:
Mean annual soil temperature: 6 to 9 degrees C
Mean summer soil temperature: 10 to 13 degrees C
Mean annual precipitation: 482 to 686 millimeters
Depth to secondary calcium carbonate: greater than 152 centimeters
Depth to stratified horizons: 20 to 50 centimeters
Particle-size control section (weighted average):
Clay content: 1 to 5 percent
Sand content: 75 to 90 percent
Rock fragments: 60 to 90 percent total rounded and subrounded fragments derived predominantly from igneous and metamorphic rocks, of which 40 to 60 percent are gravel, 10 to 30 percent cobble, and 0 to 10 percent stones
A horizon:
Hue: 10YR
Value: 2 or 3 moist, 4 dry
Chroma: 1 or 2
Texture: very gravelly loam, very gravelly sandy loam
Rock fragments: 35 to 50 percent
Reaction: neutral or slightly acid (pH 6.1 to 7.3)
Some pedons do not have an AC horizon.
C horizon:
Hue: 10YR
Value: 4 or 5 moist, 5 or 6 dry
Chroma: 2 or 3
Texture: when mixed, it is extremely gravelly coarse sand, extremely gravelly sand, extremely gravelly loamy sand, and extremely cobbly sand; strata 2 to 10 centimeters thick consisting of extremely gravelly fine sand, extremely gravelly fine sandy loam, extremely cobbly fine sand and/or extremely cobbly fine sandy loam are common throughout
Rock fragments: 60 to 90 percent
Reaction: neutral or slightly acid (pH 6.1 to 7.3)
COMPETING SERIES: There are no established series in this taxonomic class.
GEOGRAPHIC SETTING:
Parent material: Gravelly alluvium derived from mixed igneous and metamorphic rocks.
Landform: Toeslopes on flood plains and lower footslopes on terraces
Slopes: 1 to 9 percent
Elevation: 1,280 to 1,830 meters
Mean annual air temperature: 5.6 to 7.5 degrees C
Precipitation pattern: Over half the mean annual precipitation on average falls as rain and snow from April through mid-July.
Frost-free period: 100 to 140 days.
GEOGRAPHICALLY ASSOCIATED SOILS:
Grizzly - loamy-skeletal and has argillic horizons; on sloping to very steep backslopes on mountain valley slopes above Falsebottom soils
Hisega - loamy-skeletal, and has mollic epipedons; on sloping to very steep backslopes on mountain valley slopes above Falsebottom soils
Pactola - loamy-skeletal and has argillic horizons; on sloping to very steep backslopes on mountain valley slopes above Falsebottom soils
Rapidcreek(T) - is loamy-skeletal over sandy or sandy-skeletal and is formed in alluvium from mixed sedimentary rocks; on similar landscape positions
DRAINAGE AND PERMEABILITY: Somewhat excessively drained; very low to low runoff; very rapid permeability; rarely to occasionally flooded for very brief periods during the months of March through August.
USE AND VEGETATION: Falsebottom soils are in a mixed deciduous woodland and grassland. They are utilized for livestock grazing, and wildlife habitat. The native vegetation consists of an overstory of narrowleaf cottonwood, bur oak, and occasional ponderosa pine; understory species include currant, raspberry, timothy, various species of bluegrass, bearded wheatgrass, milkweed, and numerous forbs.
DISTRIBUTION AND EXTENT: Falsebottom soils occur in 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: Update of the Soil Survey of Lawrence County, South Dakota. The name is taken from the stream on which the type location for the series is located.
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Series control section: The zone from 0 to 152 centimeters.
Particle-size control section: The zone from 25 to 100 centimeters. (AC and C1 horizons)
Ochric epipedon: The zone from 0 to 13 centimeters. (A horizon)
Taxonomic Version: Keys to Soil Taxonomy, Ninth Ed., 2003
ADDITIONAL DATA: None at present.