LOCATION TANNAHILL ID+OR

Established Series
Rev. RJB/DMD
03/2013

TANNAHILL SERIES

The Tannahill series consists of deep, well drained soils that formed in material weathered from fine grained igneous rocks, mainly basalt, with some loess in the surface horizons. Tannahill soils are on south and west facing canyon slopes and have gradients of 7 to 90 percent. The average annual precipitation is about 14 inches and the average annual air temperature is about 52 degrees F.

TAXONOMIC CLASS: Loamy-skeletal, mixed, superactive, mesic Calcic Argixerolls

TYPICAL PEDON: Tannahill very cobbly loam, rangeland. (Colors are for dry soils unless otherwise noted.)

A1--0 to 3 inches; dark brown (7.5YR 4/2) very cobbly loam, very dark brown (7.5YR 2/2) moist; moderate fine and very fine granular structure; slightly hard, friable, slightly sticky and slightly plastic; many fine roots; many fine interstitial pores; 15 percent cobbles, 30 percent gravel; slightly alkaline (pH 7.4); clear wavy boundary.

A2--3 to 10 inches; dark brown (7.5YR 3/2) very gravelly silty clay loam, dark brown (7.5YR 3/2) moist; strong fine and very fine subangular blocky structure; very hard, friable, sticky and plastic; many fine roots; many fine tubular pores; 5 percent cobbles, 40 percent gravel; slightly alkaline (pH 7.6); clear wavy boundary. (Combined thickness of the A horizon is 5 to 14 inches.)

Bt--10 to 19 inches; brown (7.5YR 5/3) extremely gravelly silty clay loam, dark brown (10YR 3/3) moist; strong fine subangular blocky structure; extremely hard, very firm, sticky and plastic; common fine roots; many fine tubular pores; 5 percent cobbles, 60 percent gravel; few faint clay films on peds and in pores; slightly alkaline (pH 7.8); clear wavy boundary. (5 to 19 inches thick)

Bk1--19 to 26 inches; pale brown (10YR 6/3) extremely gravelly loam, dark brown (10YR 4/3) moist; moderate fine subangular blocky structure; slightly hard, friable, sticky and plastic; common fine roots; many fine tubular pores; 5 percent cobbles, 60 percent gravel; common fine veins and soft masses of calcium carbonate; violently effervescent; moderately alkaline (pH 8.2); clear irregular boundary.

Bk2--26 to 38 inches; very pale brown (10YR 7/3) extremely gravelly loam, dark brown (10YR 4/3) moist; moderate fine subangular blocky structure slightly hard, friable, slightly sticky and slightly plastic; few fine roots; many fine tubular pores; 5 percent cobbles, 60 percent gravel; common fine veins and soft masses of calcium carbonate, more lime than in the Bk1 horizon; greatest concentration of lime in pedon; violently effervescent; strongly alkaline (pH 8.6); clear wavy boundary. (Combined thickness of the Bk horizon is 13 to 24 inches.)

C--38 to 52 inches; pale brown (10YR 6/3) extremely gravelly loam, dark brown (10YR 4/3) moist; moderate fine and very fine subangular blocky structure; slightly hard, friable, slightly sticky and slightly plastic; few fine roots; many fine tubular pores; 5 percent cobble, 60 percent gravel; violently effervescent; strongly alkaline (pH 8.6); abrupt wavy boundary. (0 to 15 inches thick)

2R--52 inches; basalt, few roots in cracks.

TYPE LOCATION: Idaho County, Idaho; 110 feet east on road from water tank 0.2 miles east of Highway 95 at trailer park, in the NE 1/4, NE 1/4 of section 27, T.28N., R.1E.

RANGE IN CHARACTERISTICS: Depth to bedrock is 40 to 60 inches or more. The mollic epipedon is 10 to 20 inches thick and may include the upper part of the argillic horizon. The top of the argillic horizon is within 24 inches of the surface and this horizon contains more than 35 percent rock fragments. Average annual soil temperature ranges from 49 to 56 degrees F. Average summer soil temperature ranges from 65 to 70 degrees F. The soils are usually moist but are dry for 45 to 90 days in the summer.

The A horizon has hue of 10YR or 7.5YR, value of 4 or 5 dry, 2 or 3 moist and chroma of 2 or 3 moist or dry.

The Bt horizon has hue of 10YR or 7.5Y, value of 5 or 6 dry, 3 to 5 moist and chroma of 3 or 4. It is very gravelly silty clay loam, very gravelly clay loam, very cobbly loam, very cobbly clay loam, extremely cobbly clay loam, extremely cobbly loam, extremely stony loam, extremely stony silt loam, or extremely stony clay loam. It has 20 to 35 percent clay. Reaction is 7.4 to 9.0. The lower part of this horizon is calcareous in some pedons.

The Bk horizon has value of 5 to 7 dry, 4 to 6 moist and chroma of 3 or 4 moist or dry. It is extremely gravelly loam, extremely stony loam, extremely stony silt loam, very stony loam, or very stony silt loam. It is 15 to 27 percent clay. It has less than 15 percent calcium carbonate.

COMPETING SERIES: These are the Butterfield and Kapod series. Butterfield soils have a lithic contact at a depth of 20 to 40 inches. Kapod soils have very cobbly clay loam or sandy clay loam argillic horizons and an average annual soil temperature of 48 to 51 degrees F.

GEOGRAPHIC SETTING: Tannahill soils are on steep south- and west-facing canyon slopes and have gradients of 7 to 90 percent. They formed in residuum from fine grained igneous rocks, mainly basalt with some loess in the upper layers. Elevations are 1,200 to 2,800 feet. The climate is dry subhumid. Average annual precipitation is typically 12 to 16 inches with most of it coming as rainfall. In northeastern Oregon, the average annual precipitation ranges to 25 inches. Average January temperature is 34 degrees F.; average July temperature is 74 degrees F. Average annual temperature is 47 to 54 degrees F. Frost-free season is about 100 to 180 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Lickskillet and Lawyer soils. Lickskillet soils are less than 20 inches deep to bedrock. Lawyer soils have a mollic epipedon more than 20 inches thick.

DRAINAGE AND PERMEABILITY: Well drained; medium to very rapid runoff; moderately slow permeability.

USE AND VEGETATION: Most is used for grazing by livestock and big game animals, some for recreation. The natural vegetation is mainly bluebunch wheatgrass, Sandberg bluegrass, arrowleaf balsamroot and pear cactus.

DISTRIBUTION AND EXTENT: West-central Idaho, northeastern Oregon and southeastern Washington; MLRA 9. The series is of moderate extent.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Portland, Oregon

SERIES ESTABLISHED: Idaho County, Idaho, 1976.

REMARKS: Diagnostic horizons and features:

Mollic epipedon - from 0 to 19 inches (A1, A2, and Bt horizons)

Argillic horizon - from 10 to 19 inches (Bt horizon)

Calcic feature - from 19 to 38 inches (Bk1 and Bk2 horizons)

National Cooperative Soil Survey
U.S.A.