LOCATION DUNCKLEY                CO

Tentative Series
Rev. DLS/GB/KLS
01/2023

DUNCKLEY SERIES

The Dunckley series consists of deep, well drained soils that formed in colluvium derived from sandstone. These soils are on mountain side slopes and have slopes ranging from 25 to 65 percent. Mean annual air temperature is about 3 degrees C, and the mean annual precipitation is about 510 mm.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive Ustic Palecryolls

TYPICAL PEDON: Dunckley loam - brushy rangeland. (Colors are for dry soil unless otherwise noted.)

Oi--0 to 5 cm; undecomposed leaves and twigs.

Oa--5 to 8 cm; decomposed leaves and twigs.

A1--8 to 18 cm; dark brown (10YR 3/3) loam, very dark brown (10YR 2/2) moist; weak fine granular structure; soft, very friable; slightly sticky and nonplastic; many very fine and fine roots and few medium roots; neutral; clear smooth boundary. (8 to 18 cm thick)

A2--18 to 33 cm; brown (10YR 4/3) loam, very dark grayish brown (10YR 3/2) moist; weak medium subangular blocky structure parting to weak fine granular; soft, very friable; slightly sticky and nonplastic; many fine and medium roots and few medium roots; 10 percent pebbles; neutral; clear smooth boundary. (13 to 23 cm thick)

E--33 to 56 cm; very pale brown (10YR 7/3) very gravelly loam, light yellowish brown (10YR 6/4) moist; weak medium subangular blocky structure parting to weak fine granular; soft, very friable; slightly sticky and nonplastic; common fine and few medium roots; 30 percent pebbles, 15 percent cobbles, 5 percent stones; neutral; gradual smooth boundary. (20 to 25 cm thick)

E/B--56 to 81 cm; mixed (E) 60 percent very pale brown (10YR 7/3) very gravelly loam, light yellowish brown (10YR 6/4) moist; weak medium subangular blocky structure parting to weak fine granular; soft, very friable; slightly sticky and nonplastic; (B) 40 percent yellowish brown (10YR 5/6) very gravelly clay loam, yellowish brown (10YR 5/6) moist; weak fine and moderate subangular blocky structure; soft, very friable, slightly sticky and slightly plastic; few medium roots; 25 percent pebbles, 10 percent cobble, 5 percent stone; neutral; diffuse smooth boundary. (0 to 25 cm thick)

B/E--81 to 106 cm; mixed (B) 80 percent yellowish brown (10YR 5/6) very gravelly clay loam, light yellowish brown (10YR 6/4) moist; moderate medium and weak fine subangular blocky structure; slightly hard, friable, sticky and plastic; (E) 20 percent very pale brown (10YR 7/3) very gravelly loam, light yellowish brown (10YR 6/4) moist; weak medium subangular blocky structure; soft, very friable, slightly sticky and nonplastic; few medium roots; 30 percent pebbles, 15 percent cobbles, 5 percent stones, neutral, gradual irregular boundary. (20 to 28 cm thick)

Bt--106 to 159 cm; yellowish brown (10YR 5/6) very cobbly clay loam; yellowish brown (10YR 5/6) moist; moderate medium subangular blocky structure parting to weak fine subangular block; slightly hard, very friable, sticky and plastic; few medium roots; continuous moderately thick clay films on faces of peds; 35 percent pebbles, 20 percent cobbles, 5 percent stones; neutral; clear smooth boundary. (50 to 75 cm thick)

BC--159 to 184 cm; brownish yellow (10YR 6/6) extremely stony loam; yellowish brown (10YR 5/6) moist; moderate medium subangular blocky structure parting to moderate fine subangular blocky; slightly hard, friable, slightly sticky and plastic; many moderately thick clay films on faces of peds; 10 percent pebbles, 10 percent cobbles, 50 percent stones, neutral.

TYPE LOCATION: Routt County, Colorado; about 14 km southeast of Hayden, 365 meters north and 245 meters east of the SW corner of sec. 16, T. 5 N., R. 87 W.

RANGE IN CHARACTERISTICS:
Mean annual soil temperature--4 to 6 degrees C
Mean summer soil temperature--12 to 13 degrees C
Depth to top of argillic horizon--60 to 100 cm

Particle-size control section:
Clay content--28 to 35 percent
Rock fragment content--35 to 65 percent

A horizon
Hue--10YR or 7.5YR
Value--3 or 4 dry, 2 or 3 moist
Chroma--2 to 3
Texture-typically loam, but is a cobbly loam in some pedons
Rock fragment content--0 to 10 percent gravel, 0 to 10 percent cobbles

E horizon
Hue--10YR or 7.5YR
Value--6 or 7 dry, 5 or 6 moist
Chroma--2 through 4
Texture--very gravelly loam, very gravelly fine sandy loam or cobbly loam
Rock fragment content--10 to 25 percent gravel, 10 to 15 percent cobbles, 0 to 5 percent stones

Bt horizon
Hue--10YR or 7.5YR
Value--5 or 6 dry, 5 or 6 moist
Chroma--4 through 6
Texture--very cobbly clay loam, or very stony clay loam
Rock fragment content--20 to 35 percent gravel, 10 to 20 percent cobbles, 5 to 15 percent stones

COMPETING SERIES: These are the Lucky Star, Nordic, (T) Norway Flat, and Schuster series. The Lucky Star soils have a more acid soil reaction and redder hues in the Bt horizon. Nordic soils are more acid in reaction, lack both E/B horizons, and B/E horizons, and have an E horizon that is 50 to 70 cm thick. The (T)Norway Flat soils have less than 18 percent clay in the argillic horizon and have E/B horizons below a depth of 100 cm. The Schuster soils have hues of 5YR or 2.5YR in the Bt horizon.

GEOGRAPHIC SETTING:
Landform-mountain side slopes
Elevations--2200 to 2600 meters
Slope--25 to 65 percent
Parent material--colluvium derived from sandstone
Mean annual air temperature--3 to 4 degrees C
Mean summer air temperature--11 to 12 degrees C
Mean annual precipitation--460 to 560 mm
Frost-free period--40 to 65 days

GEOGRAPHICALLY ASSOCIATED SOILS: None listed

DRAINAGE AND PERMEABILITY: Well drained; medium or rapid runoff; moderate permeability

USE AND VEGETATION: These soils are used for rangeland and livestock grazing and wildlife habitat.

DISTRIBUTION AND EXTENT: Dunckley soils are of small extent in northwestern Colorado; MLRA 48A

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Bozeman, Montana

SERIES ESTABLISHED: Routt County Area, Colorado, 1981

REMARKS: Converted to metric and O horizons were updated to start at zero. Competing series section was not updated. 12/2022

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National Cooperative Soil Survey
U.S.A.