LOCATION FONCE COEstablished Series
TAXONOMIC CLASS: Fine-loamy, mixed, superactive, frigid Ustic Calciargids
TYPICAL PEDON: Fonce sandy loam, rangeland. (Colors are dry soil unless otherwise noted.)
A--0 to 3 inches; brown (10YR 5/3) sandy loam, dark yellowish brown (10YR 4/4) moist; moderate fine and medium granular structure; soft, friable, slightly sticky and nonplastic; neutral (pH 7.2); clear smooth boundary. (2 to 4 inches thick)
Bt1--3 to 10 inches; light brown (7.5YR 6/4) sandy clay loam, brown (7.5YR 4/4) moist; moderate medium subangular blocky structure; slightly hard, friable, sticky and slightly plastic; common distinct clay films on ped faces; mildly alkaline (pH 7.6); clear wavy boundary. (5 to 15 inches thick)
Bt2--10 to 15 inches; light yellowish brown (10YR 6/4) sandy clay loam, yellowish brown (10YR 5/4) moist; moderate medium prismatic structure parting to moderate coarse subangular blocky; slightly hard, firm, sticky, and slightly plastic; common distinct clay films on ped faces; 5 percent pebbles; mildly alkaline (pH 7.6); abrupt wavy boundary. (5 to 15 inches thick)
2Bk1--15 to 23 inches; white (10YR 8/2) and very pale brown (10YR 7/3) gravelly sandy clay loam, light gray (10YR 7/2) and pale brown (10YR 6/3) moist; weak coarse subangular blocky structure; hard, firm, sticky and nonplastic; 15 percent pebbles; disseminated calcium carbonate, violently effervescent, 30 percent calcium carbonate equivalent; moderately alkaline (pH 8.4); clear wavy boundary. (0 to 10 inches thick)
2Bk2--23 to 33 inches; white (10YR 8/2) very gravelly coarse sandy loam, light gray (10YR 7/2) moist; massive; soft, friable, slightly sticky and nonplastic; 40 percent pebbles, 5 percent cobbles, disseminated calcium carbonate, violently effervescent, 20 percent calcium carbonate equivalent; strongly alkaline (pH 8.6); gradual wavy boundary. (10 to 30 inches thick)
2Bk3--33 to 53 inches; light gray (10YR 7/2) gravelly sand, very pale brown (10YR 7/3) moist; single grain; loose, nonsticky and nonplastic; 20 percent pebbles, disseminated calcium carbonate, violently effervescent, 10 percent calcium carbonate equivalent; strongly alkaline (pH 8.6); gradual wavy boundary. (5 to 20 inches thick)
2Bk4--53 to 59 inches; light gray (10YR 7/2) gravelly coarse sand, very pale brown (10YR 7/4) moist; single grain, loose, nonsticky and nonplastic; 25 percent pebbles, visible calcium carbonate occurs only as pendants on pebbles, strongly effervescent; moderately alkaline (pH 8.4); gradual irregular boundary. (0 to 10 inches thick)
2C--59 to 60 inches; very pale brown (10YR 8/3) gravelly coarse sand, very pale brown (10YR 7/4) moist; single grain, loose, nonsticky and nonplastic; 25 percent pebbles; mildly alkaline (pH 7.8).
TYPE LOCATION: Moffat County, Colorado; approximately 35 miles northwest of Craig, about 600 feet south and 60 feet west of the northeast corner of Sec. 8, T. 11 N., R. 94 W. Longitude: 107 degrees, 57 minutes, 47 seconds west. Latitude: 40 degrees, 56 minutes, 2 seconds north.
RANGE IN CHARACTERISTICS: Mean annual soil temperature ranges from 44 degrees to 46 degrees F., and mean summer soil temperature ranges from 62 to 64 degrees F. Depth to the base of the argillic horizon is 12 to 25 inches. Depth to secondary calcium carbonate is 8 to 25 inches. The calcic horizon contains 15 to 40 percent calcium carbonate equivalent. At least one subhorizon below the argillic horizon and above 40 inches contains 35 to 60 percent rock fragments.
The A horizon has hue of 10YR or 7.5YR, value of 5 or 6 dry, 3 or 4 moist, and chroma of 2 through 4. Reaction is neutral or mildly alkaline.
The Bt horizon has hue of 10YR or 7.5YR, value of 5 or 6 dry, 4 or 5 moist, and chroma of 4 through 6. Rock fragments range from 5 to 30 percent. It is sandy clay loam, sandy loam, gravelly sandy loam, or gravelly sandy clay loam. Clay content is 18 to 27 percent and there is 35 to 55 percent fine and coarser sand. Reaction is neutral or mildly alkaline.
The 2Bk1 and 2Bk2 horizons have hue of 2.5Y through 7.5YR, value of 6 through 8, 5 through 7 moist, and chroma of 2 through 4. Clay content is 5 to 24 percent. It is very cobbly, very gravelly, or gravelly modifiers of sandy clay loam, sandy loam, or loamy sand. Content of rock fragments in individual horizons ranges from 20 to 60 percent with at least one horizon containing more than 35 percent rock fragments. Reaction is moderately alkaline or strongly alkaline.
The 2Bk3, 2Bk4, and 2C horizons have hue of 10YR or 7.5YR, value of 6 through 8, 5 through 7 moist, and chroma of 2 through 6. It is gravelly, very gravelly, or very cobbly sandy loam, coarse sandy loam, loamy sand, loamy coarse sand, coarse sand, or sand. Clay content is 5 to 18 percent. Rock fragments range from 20 to 60 percent. Reaction of the 2Bk3 and 2Bk4 horizons is moderately alkaline or strongly alkaline. Reaction of the 2C horizon is mildly alkaline or moderately alkaline.
COMPETING SERIES: These are the Alcova (WY), Almy (WY), Alogia(WY), Anchutz (WY), Antonito (NM), Bateson (WY), Bluerim (WY), Bonfri (MT), Cushool (WY), Cutback(WY), Diamondville (WY), Fluetsch (CO), Forelle (CO), Grubrob (CO), Harsha (CO), Hickey(WY), Maysprings (CO), Rawah (CO), Regnaps (WY), Rock River (WY), Satanka(WY), Stunner (CO), Stylite(WY), Taffom (CO), and Wycolo (WY) series. Antonito, Bluerim, Bonfri, Cushool, Cutback, Diamondville, Grubrob, Regnaps, Satanka, and Wycolo soils have bedrock at a depth of 20 to 40 inches. Alcova, Almy, Bateson, Fluetsch, Forelle, Harsha, Rawah, Rock River, and Satanka soils lack a calcic horizon. Stunner has less than 35 percent fine or coarser sand in the particle-size control section and C horizons, and lacks skeletal horizons below the argillic horizon. Hickey soils have mean annual soil temperatures that range from 38 to 43 degrees F. Maysprings and Taffom soils lack calcium carbonates 40 inches. Alogia soils are moderately well drained with gypsum accumulation below 22 inches. Anchutz soils need further study. Stylite soils have a gypsic horizon.
GEOGRAPHIC SETTING: Fonce soils are on plateaus and fan terraces. Slopes range from 1 to 30 percent. The soil formed in alluvium and colluvium derived from sandstone and in aeolian deposits over relict stream deposits. Elevation ranges from 6,000 to 7,800 feet. The mean annual precipitation ranges from 9 to 13 inches. Mean annual temperature ranges from 42 to 45 degrees F. The frost-free period is about 75 to 95 days. July is the driest month during the growing season.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Rock River soils and the Ryark soils. Ryark soils lack calcic horizons and gravelly substratums.
DRAINAGE AND PERMEABILITY: Well drained; slow runoff; moderate permeability.
USE AND VEGETATION: These soils are used for livestock grazing and wildlife habitat. Native vegetation consists of western wheatgrass, thickspike wheatgrass, Indian ricegrass, needleandthread, Sandberg bluegrass, and sagebrush.
DISTRIBUTION AND EXTENT: The soils occur in northwestern Colorado. The series is of small extent. Total area is about 10,000 acres.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Moffat County (Moffat County Area), Colorado, 1991.
REMARKS: Diagnostic horizons recognized in this pedon are the argillic horizon the zone from 3 to 15 inches, and the calcic horizon the zone from 15 to 33 inches. Last updated by the state 12/90.