LOCATION PLATDON COEstablished Series
TAXONOMIC CLASS: Fine-loamy over sandy or sandy-skeletal, mixed, superactive Cumulic Cryaquolls
TYPICAL PEDON: Platdon loam, in wetland grasses at an elevation of 9,060 feet. (Colors are for dry soil unless otherwise noted.) Described on June 16, 1982.
A--0 to 8 inches; dark gray (10YR 4/1) loam, black (10YR 2/1) moist; moderate fine granular structure; very friable, soft, slightly sticky, slightly plastic; 10 percent gravel; strongly effervescent; moderately alkaline (pH 8.0); clear smooth boundary.
Ag--8 to 18 inches; dark gray (10YR 4/1) loam, black (10YR 2/1) moist; moderate fine subangular blocky structure; very friable, soft, slightly sticky, slightly plastic; common fine prominent strong brown (7.5YR 4/6) masses of oxidized iron, and common fine faint gray (10YR 5/1) iron depletions; 10 percent gravel; neutral (pH 7.2); clear smooth boundary. (combined thickness of the A horizons is 10 to 24 inches)
Cg1--18 to 30 inches; gray (10YR 5/1) very gravelly sandy clay loam, very dark gray (10YR 3/1) moist; massive; very friable, slightly hard, slightly sticky, nonplastic; many medium prominent strong brown (7.5YR 4/6) masses of oxidized iron, and many medium faint light brownish gray (10YR 6/2) iron depletions; 15 percent cobbles and 35 percent gravel; neutral (pH 7.2); clear smooth boundary. (6 to 16 inches thick)
2Cg2--30 to 60 inches; light brownish gray (10YR 6/2) extremely gravelly sand, dark grayish brown (10YR 4/2) moist; single grain; loose, nonsticky, nonplastic; many medium prominent strong brown (7.5YR 4/6) masses of oxidized iron, and many medium faint gray (10YR 5/1) iron depletions; 20 percent cobbles and 50 percent gravel; neutral (pH 7.2).
TYPE LOCATION: Park County, Colorado; about 5 miles northwest of Hartsel; about 2,600 feet north and 2,050 feet east of the southwest corner of section 23, T. 11 S., R. 76 W.; Hartsel USGS quad; latitude 39 degrees 04 minutes 34.3 seconds N. and longitude 105 degrees 51 minutes 26.1 seconds W., NAD 1983.
RANGE IN CHARACTERISTICS:
Soil moisture: Aquic soil moisture regime
Mean annual soil temperature: 37 to 41 degrees F.
Mean summer soil temperature: 51 to 58 degrees F.
Thickness of the mollic epipedon: 20 to 35 inches
Depth to lithologic discontinuity: 20 to 35 inches
Depth to aquic conditions and seasonal endosaturation: 0 to 20 inches (April through August)
Depth to redoximorphic features: 0 to 20 inches
Particle-size control section (weighted averages):
Clay content: 18 to 35 percent in the upper part, 2 to 10 percent in the lower part
Rock fragment content: 20 to 30 percent in the upper part, 50 to 70 percent in the lower part
A and Ag horizons (includes an AB in some pedons):
Hue: 7.5YR to 2.5Y, or N
Value: 2 to 5 dry, 1 to 3 moist
Chroma: 0 to 2 dry, 0 to 3 moist
Texture: loam, clay loam
Clay content: 18 to 35 percent
Gravel content: 2 to 15 percent
Calcium carbonate equivalent: 0 to 5 percent
Reaction: neutral to moderately alkaline
Cg horizon (Bg in some pedons):
Hue: 10YR, 2.5Y
Value: 2 to 6 dry; 2 to 4 moist
Chroma: 0 to 2 dry; 0 to 2 moist
Texture: gravelly sandy loam, gravelly loam, very gravelly loam, very gravelly sandy clay loam, very gravelly clay loam
Clay content: 18 to 35 percent
Rock fragment content: 15 to 60 percent; 15 to 45 percent gravel; 0 to 15 percent cobbles
2C horizon (present in some pedons):
Hue: 10YR
Value: 3 to 7, dry or moist
Chroma: 4 to 8, dry or moist
Texture: very gravelly coarse sand, very gravelly loamy sand, very gravelly loamy coarse sand
Clay content: 2 to 10 percent
Fragment content, total: 35 to 60 percent
Fragment size and content: 35 to 55 percent gravel; 0 to 5 percent cobbles
Reaction: neutral
2Cg horizon:
Hue: 10YR through 5Y
Value: 4 to 6 dry; 3 to 6 moist
Chroma: 1 or 2 dry; 1 or 2 moist
Texture: extremely gravelly coarse sand, extremely gravelly loamy coarse sand, extremely gravelly loamy sand, extremely gravelly sand
Clay content: 2 to 10 percent
Rock fragment content: 60 to 85 percent; 50 to 70 percent gravel, 0 to 25 percent cobbles
COMPETING SERIES: These are the
Hovarka,
Kilgore, and
Lemhi series.
Hovarka, Lemhi, and Kilgore soils have less than 20 percent (weighted average) rock fragments in the upper part of the particle-size control section. In addition, Hovarka and Lemhi soils border a xeric moisture regime.
GEOGRAPHIC SETTING:
Parent material: alluvium from mixed sources
Landform: drainageways, flood plains, and flood plain steps
Slopes: 0 to 3 percent
Elevation: 8,200 to 10,000 feet
Mean annual temperature: 35 to 40 degrees F.
Mean annual precipitation: 10 to 23 inches
Precipitation pattern: Monthly precipitation is lowest in winter and greatest in July and August.
Frost-free period: 50 to 80 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Hodden, Adderton, and Spinth soils. Hodden soils have argillic and calcic horizons and are on outwash terraces. Adderton soils do not have endosaturation and are on more elevated positions of flood plains. Spinth soils have calcic horizons and accumulations of sodium and are on similar landforms as Platdon soils.
DRAINAGE AND PERMEABILITY: poorly drained or very poorly drained, moderate or moderately slow permeability, rarely or frequently flooded for brief periods during the months of May through September.
USE AND VEGETATION: These soils are used for grazing and recreation. Native vegetation consists of sedges, western wheatgrass, foxtail barley, prairie junegrass, slender wheatgrass, alkali sacaton, Sandberg bluegrass, alkali bluegrass, inland saltgrass, plantain, Rocky Mountain iris, and Baltic rush.
DISTRIBUTION AND EXTENT: Central Colorado; LRR E, MLRA 48B; moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Park County, Colorado, Teller-Park Soil Survey Area, 2010. The name is coined.
REMARKS:
Diagnostic horizons and features recognized in this pedon are:
Series control section: The zone from 0 to 60 inches.
Particle-size control section: The zone from 10 to 40 inches. (part of the Ag, Cg1, and part of 2Cg2 horizons)
Mollic epipedon: from 0 to 30 inches. (A, Ag, Cg1 horizons)
Aquic conditions: The zone from 8 to 60 inches. (Ag, Cg1, 2Cg2 horizons)
Redox concentrations: 8 to 60 inches. (Ag, Cg1, 2Cg2 horizons)
Endosaturation: The zone from 8 to 60 inches. (Ag, 2Cg1, 2Cg2 horizons)
Lithologic discontinuity: sandy-skeletal material at 30 inches (upper boundary of 2Cg2 horizon).
Taxonomic Version: classified according to the Eleventh edition, 2010.