LOCATION WALKNOLLS               CO+UT

Established Series
Rev. WPT/CRP/JCK
12/2017

WALKNOLLS SERIES

The Walknolls series consists of very shallow and shallow, well drained soils that formed in slope alluvium or colluvium over residuum from sandstone. Walknolls soils are on hills, cuestas, homoclinal ridges, structural benches, canyon walls and escarpments. Slopes are 2 to 70 percent. Mean annual precipitation is about 250 mm, and mean annual air temperature is about 9 degrees C.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, mesic Lithic Ustic Haplocalcids

TYPICAL PEDON: Walknolls channery sandy loam - rangeland. (Colors are for dry soil unless otherwise noted.)

A--0 to 10 cm; pale brown (10YR 6/3) channery sandy loam; brown (10YR 4/3) moist; moderate fine granular structure; soft, very friable, slightly sticky and slightly plastic; 15 percent channers; strongly effervescent; moderately alkaline; clear smooth boundary. (5 to 20 cm thick)

BCk--10 to 30 cm inches; pale brown (10YR 6/3) very channery sandy loam; brown (10YR 4/3) moist; massive; slightly hard, very friable, slightly sticky and slightly plastic; many prominent carbonate coats on bottom surfaces of rock fragments; 70 percent channers and 10 percent flagstones; violently effervescent; moderately alkaline; gradual smooth boundary. (15 to 45 cm thick)

R--30 cm; hard sandstone bedrock.

TYPE LOCATION: Rio Blanco County, Colorado; about 21 kilometers west and 5 kilometers south of Rangely; 426 meters south and 671 meters east of the northwest corner of Sec. 26, T. 2 N., R. 104 W. U.S.G.S. Walsh Knolls quad.; Lat. 40 degrees, 07 minutes, 04 seconds N., and Long. 109 degrees, 02 minutes, 17 seconds W.

RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 9 to 13 degrees C
Depth to lithic contact - 20 to 50 cm
Particle-size control section (weighted average):
Clay content - 8 to 27 percent
Rock fragments - 35 to 90 percent, generally sandstone channers and flagstones

A horizon
Hue: 10YR or 2.5Y
Value: 4, 5, 6, or 7 dry; 4 or 5 moist
Chroma: 2, 3, or 4 dry or moist
Texture: sandy loam or loam
Clay content: 8 to 25 percent
Rock fragments: 15 to 75 percent channers and flagstones
Reaction: pH 7.4 to 8.4

BCk horizon
Hue: 10YR or 2.5Y
Value: 4, 5, 6, or 7 dry; 4, 5, or 6 moist
Chroma: 2, 3, 4 or 6 dry or moist
Texture: sandy loam, fine sandy loam or loam
Clay content: 8 to 27 percent
Rock fragments: 35 to 90 percent channers and flagstones
Calcium carbonate equivalent: 5 to 40 percent
Reaction: pH 8.0 to 8.4

Some pedons have a Bk above or in place of, the BCk horizon.

COMPETING SERIES:
Mellenthin (UT) - have hue redder than 10YR
Neveset (UT) - have hue redder than 10YR

GEOGRAPHIC SETTING:
Elevation - 1,554 to 2,286 meters
Landform - hills, cuestas, homoclinal ridges, structural benches, canyon walls and escarpments
Slope - 2 to 70 percent
Parent material - slope alluvium or colluvium over residuum
Mean annual precipitation - 203 to 305 mm
Precipitation pattern - even yearly distribution with slight increase in late summer and early fall
Mean annual air temperature - 7.2 to 12 degrees C
Frost-free period - 105 to 165 days

GEOGRAPHICALLY ASSOCIATED SOILS: None listed.

DRAINAGE AND PERMEABILITY: Well drained; moderate to moderately rapid permeability.

USE AND VEGETATION: Walknolls soils are used for rangeland and wildlife habitat. Native vegetation is James' galleta, Indian ricegrass, needle and thread, shadscale saltbush, Wyoming big sagebrush, winterfat and squirreltail. Some areas have scattered Utah juniper trees.

DISTRIBUTION AND EXTENT: Walknolls soils are extensive in western Colorado and eastern Utah. MLRA 34B and 36.

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

SERIES ESTABLISHED: Rio Blanco Area, Colorado, 1979.

REMARKS: Diagnostic horizons and features recognized are:
Ochric epipedon from - 0 to 10 cm (A horizon)
Calcic horizon from - 10 to 30 cm (Bk horizon)
Lithic contact at - 30 cm (R horizon)
Particle-size control section from - 0 to 30 cm (A and Bk horizons)


Walknolls soils have a mesic temperature regime and an aridic moisture regime bordering on ustic.

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National Cooperative Soil Survey
U.S.A.