LOCATION THEDALUND               CO+MT UT WY

Established Series
GB
12/2021

THEDALUND SERIES

The Thedalund series consists of moderately deep, well drained, moderately permeable soils formed in thick calcareous alluvial materials derived from sedimentary rock. Thedalund soils are on hills and ridges and have slopes of 0 to 30 percent. The mean annual precipitation is about 15 inches and mean annual temperature is about 49 degrees F.

TAXONOMIC CLASS: Fine-loamy, mixed, superactive, calcareous, mesic Ustic Torriorthents

TYPICAL PEDON: Thedalund clay loam - grassland. (Colors are for dry soil unless otherwise noted.)

A--0 to 4 inches; light brownish gray (10YR 6/2) clay loam, dark grayish brown (10YR 4/2) moist; moderate very fine granular structure; soft, friable; strongly effervescent; moderately alkaline; gradual wavy boundary. (3 to 6 inches thick)

AC--4 to 8 inches; light yellowish brown (2.5Y 6/3) light clay loam, olive brown (2.5Y 4/3) moist; weak medium and fine subangular blocky structure parting to moderate fine granular; strongly effervescent; moderately alkaline; gradual wavy boundary. (3 to 6 inches thick)

C--8 to 30 inches; pale yellow (2.5Y 7/3) light clay loam, light yellowish brown (2.5Y 6/3) moist; massive; hard, very friable; few small concretions of secondary calcium carbonate; strongly effervescent; moderately alkaline; gradual wavy boundary. (12 to 28 inches thick)

Cr--30 inches; soft shale and interbedded soft sandstone and siltstone.

TYPE LOCATION: Arapahoe County, Colorado; 1,400 feet north and 200 feet east of the SW corner of Sec. 7, T. 4 S., R. 57 W.

RANGE IN CHARACTERISTICS: Mean annual soil temperature ranges from 47 to 58 degrees F. and mean summer soil temperature ranges from 59 to 79 degrees F. Normally, these soils are calcareous throughout but they are leached for a few inches in some pedons. Some visible secondary calcium carbonate occurs inconsistently and at variable depths. The particle size control section is generally loam or light clay loam, but clay ranges from 18 to 35 percent, silt from 20 to 55 percent and sand from 15 to 50 percent with more than 15 percent but less than 35 percent fine or coarser sand. Rock fragments range from 0 to 15 percent by volume. Depth to bedrock ranges from 20 to 40 inches.
The A horizon has hue of 5Y through 7.5YR, value of 5 through 7, 3 through 5 moist, and chroma of 2 through 4. The horizon is usually granular but has subangular blocky structure in some pedons. It is soft or slightly hard. It is mildly alkaline or strongly alkaline (pH 7.8 to 8.5).

The C horizon has hue of 5Y through 7.5YR. It is loam or clay loam with more than 18 percent clay. It is moderately alkaline or strongly alkaline (pH 8.0 to 8.6) and contains 1 to 5 percent calcium carbonate equivalent.

COMPETING SERIES: These are the El Rancho, Kim, Kishona, Neville, Pojoaque, Shavano, and Sixmile series. El Rancho, Kim, Kishona, Neville, and Pojoaque soils lack a paralithic contact at a depth of less than 40 inches. Also El Rancho, Neville and Pojoaque soils have hue of 5YR or redder. Shavano soils have a lithic contact between a depth of 20 and 40 inches, Sixmile soils have hue of 5YR or redder.

GEOGRAPHIC SETTING: Thedalund soils are on hills and ridges. Slopes range from 0 to 30 percent. The soils formed in thick calcareous alluvial fan materials derived from sedimentary rock. At the type location the average annual precipitation is 15 inches with peak periods of precipitation in the spring and early summer months. Mean annual temperature is 49 degrees F., mean summer temperature is 69 degrees F.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Kim soils and the Shingle soils. Shingle soils have bedrock at a depth of 20 inches or less.

DRAINAGE AND PERMEABILITY: Well drained; medium runoff; moderate permeability.

USE AND VEGETATION: They are used as native pastureland or as irrigated or dry cropland. Native vegetation is blue grama, sage, and cactus.

DISTRIBUTION AND EXTENT: Eastern Colorado, Wyoming and Montana. The series is of large extent.

SOIL SURVEY REGIONAL OFFICE (SSRO) RESPONSIBLE: Salina, Kansas

SERIES ESTABLISHED: Arapahoe County, Colorado, 1965.

REMARKS:
Depths were adjusted to account for the current standard of measuring O horizons. JCW 12/21.

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National Cooperative Soil Survey
U.S.A.