LOCATION ELKWALOW                CO+MT

Tentative Series
BWC/GB/KLS
01/2023

ELKWALOW SERIES

The Elkwalow series consists of deep, somewhat poorly or moderately well drained soils formed in glacial till derived from basalt. Elkwalow soils are on mesa tops. Slopes range from 0 to 10 percent. Mean annual precipitation is about 890 mm and mean annual air temperature is about 1 degrees C.

TAXONOMIC CLASS: Fine, smectitic Oxyaquic Haplocryalfs

TYPICAL PEDON: Elkwalow loam - Engelmann spruce-subalpine fir woodland. (colors are for dry soil unless otherwise noted.)

Oa--0 to 3 cm; highly decomposed needles and twigs.

A1--3 to 8 cm; brown (10YR 4/3) loam, very dark grayish brown (10YR 3/2) moist; moderate medium granular structure; soft, very friable, nonsticky and nonplastic; moderately acid (pH 5.8); clear smooth boundary.

A2--8 to 23 cm; brown (10YR 4/3) silt loam, very dark grayish brown (10YR 3/2) moist; moderate medium subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; moderately acid (pH 5.8); clear wavy boundary. (Combined thickness of A horizons - 10 to 25 cm)

E--23 to 61 cm; pink (7.5YR 7/4) silt loam, brown (7.5YR 5/4) moist; many fine and medium distinct strong brown (7.5YR 5/6 and 7.5YR 5/8) redox concentrations in the matrix, moist; weak medium and coarse subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; 5 percent pebbles; strongly acid (pH 5.4); abrupt wavy boundary. (30 to 45 cm thick)

Bt1--61 to 97 cm; brown (7.5YR 5/4) clay, dark brown (7.5YR 3/4) moist; strong medium and coarse subangular blocky structure; very hard, firm, sticky and very plastic; many distinct clay films on ped faces; 5 percent cobbles; neutral (pH 7.0); gradual irregular boundary.

Bt2--97 to 120 cm; brown (7.5YR 5/4) cobbly clay, dark brown (7.5YR 3/4) moist; strong medium and coarse subangular blocky structure; very hard, firm, sticky and very plastic; many distinct clay films on ped faces; 5 percent pebbles, 15 percent cobbles; neutral (pH 7.2); abrupt irregular boundary. (Combined thickness of Bt horizons - 50 to 70 cm)

2R--120 cm; basalt bedrock.

TYPE LOCATION: Mesa County, Colorado; on Old Land's End Road in the NW1/4 of Sec. 4, T. 12 S., R. 96 W.; Lat. 39 degrees, 2 minutes, 22 seconds N.; Long. 108 degrees, 7 minutes, 33 seconds W.

RANGE IN CHARACTERISTICS:
Mean annual soil temperature--1 to 3 degrees C
Mean summer soil temperature--6 to 7 degrees C
Depth to redoximorphic features--20 to 60 cm; saturated with a perched water table at 0.5 to 1 meter for 30 days or more during the summer
Depth to lithic contact--100 to 150 cm
Rock fragment content--5 to 25 percent

A horizons
Hue--10YR or 7.5YR
Value--4 or 5 dry, 3 or 4 moist
Chroma--2 or 3
Reaction--pH 5.6 to 7.3

E horizon
Hue--10YR or 7.5YR
Reaction--pH 5.1 to 7.3

Bt horizons
Hue--7.5YR or 5YR
Reaction--pH 6.1 to 7.3

COMPETING SERIES: There are currently no other series in this subgroup. The Potlatch soils are similar but have an aquic condition.

GEOGRAPHIC SETTING:
Landform--mesa tops
Elevation--3025 to 3250 meters
Slopes--0 to 10 percent
Parent material--glacial till derived from basalt
Mean annual precipitation--760 to 1000 mm
Mean annual air temperature--1 to 2 degrees C
Frost free period--15 to 50 days

GEOGRAPHICALLY ASSOCIATED SOILS: None listed.

DRAINAGE AND PERMEABILITY: Somewhat poorly or moderately well drained; slow to medium runoff; slow permeability. A perched water table is at 0.5 to 1 meter for 30 or more days from May 15 to July 15.

USE AND VEGETATION: This soil is used for timber production, firewood, wildlife habitat, and recreation. Dominant species are Engelmann spruce and subalpine fir.

DISTRIBUTION AND EXTENT: Elkwalow soils are of small extent in western Colorado and western Montana; MLRAs 43B and 48A

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

SERIES PROPOSED: Mesa County (Grand Mesa-West Elk Soil Survey Area) Colorado, 1988

REMARKS: Diagnostic features in this soil include:
Argillic horizon--61 to 120 cm
Oxyaquic feature--continuously saturated for 30 days or more from May 15 to July 15

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.