LOCATION TONKS                   ID+WY

Inactive Series
Rev. TWP
04/2011

TONKS SERIES

The Tonks series consists of deep, somewhat poorly drained soils that formed in mixed, stratified alluvium. Tonks soils are on low alluvial fans and bottomlands and have slopes of 0 to 2 percent. The mean annual precipitation is about 17 inches and the mean annual air temperature is about 39 degrees F.

TAXONOMIC CLASS: Fine-loamy, mixed, superactive, calcareous Typic Cryaquolls

TYPICAL PEDON: Tonks silty clay loam, meadow pasture. (Colors are for dry soil unless otherwise noted.)

A11--0 to 2 inches; dark gray (10YR 4/1) light silty clay loam, black (10YR 2/1) moist; moderate fine and medium granular structure; hard, friable, slightly sticky and slightly plastic; many fine roots (nearly a mat); many very fine interstitial pores; few pebbles; noncalcareous or very slightly calcareous; slightly alkaline (pH 7.6) clear smooth boundary. (0 to 3 inches thick)

A12--2 to 13 inches; similar to A11 horizon except common very fine, fine, and few medium roots; many very fine tubular pores; few bleached sand grains; abrupt wavy boundary. (6 to 16 inches thick)

A13ca--13 to 17 inches; grayish brown (2.5Y 5/2) silty clay loam, very dark grayish brown (10YR 3/2) moist; few coarse faint brown (10YR 5/3) mottles, brown (10YR 4/3) moist; few fine prominent strong brown (7.5YR 5/6) mottles, dark yellowish brown (10YR 4/6) moist; weak medium prismatic parting to weak medium and coarse granular structure; very hard, friable, sticky and plastic; common very fine and fine and few medium roots; many very fine tubular pores and common fine and medium tubular pores; few black krotovinas and worm holes and casts; slightly to moderately calcareous; slightly alkaline (pH 7.5); abrupt wavy boundary. (0 to 6 inches thick)

C1cag--17 to 30 inches; grayish brown (2.5Y 5/2) clay loam, dark grayish brown (2.5Y 4/2) moist; many medium and coarse prominent yellowish brown (10YR 5/4 and 5/6) mottles, which are dark yellowish brown (10YR 4/4) moist; massive; very hard, friable, sticky and plastic; few very fine roots; common very fine and few fine tubular pores; few worm holes and casts; common soft fine yellowish brown concretions; many white lime mycelia and splotches; moderately calcareous; slightly alkaline (pH 7.8); clear wavy boundary. (10 to 20 inches thick)

C2cag--30 to 41 inches; similar to C1cag horizon except few fine prominent strong brown (7.5YR 5/6) mottles; common fine veins of carbonates; slightly less calcareous than C1 horizon; slightly alkaline (pH 7.7); abrupt smooth boundary)

IICcag--41 to 49 inches; gray (2.5Y 6/1) heavy loam or silt loam, dark gray (2.5Y 4/1) moist; many medium and fine prominent light yellowish brown (10YR 6/4) mottles, yellowish brown (10YR 5/4) moist; massive; very hard, friable, slightly sticky and slightly plastic; common very fine tubular pores; very few soft yellowish concretions; few lime mycelia veins; moderately calcareous; slightly alkaline (pH 7.7); abrupt smooth boundary.

IIC4g--49 to 58 inches; similar to IIC3cag horizon but loam or fine sandy loam, gray (2.5Y 5/1) moist; common mottles; few fine tubular pores; noncalcareous; slightly alkaline (pH 7.7); abrupt smooth boundary. (0 to 15 inches thick)

IIIC5--58 to 78 inches; gray (2.5Y 5/1) light coarse sandy loam, very dark gray (2.5Y 3/1) moist; few coarse faint grayish brown (2.5Y 5/2) mottles, very dark grayish brown (2.5Y 3/2) moist; few fine prominent light yellowish brown (10YR 6/4) mottles, yellowish brown (10YR 5/4) moist; massive hard, very friable, slightly sticky and nonplastic; many very fine interstitial pores; noncalcareous; slightly alkaline (pH 7.7). (0 to 30 inches thick)

TYPE LOCATION: Teton County, Idaho; 180 feet west of the southwest corner of the SE1/4 section 34, T.6N., R.45E.

RANGE IN CHARACTERISTICS: These soils are saturated and have a temporary water table during spring and nd early summer unless they have been artifically drained. The fluctuating water table is at depths of about 30 to 50 inches during these periods and when heavily irrigated. The mean annual soil temperature is about 38 to 41 degrees F. The mean summer temperature is about 53 to 55 degrees F. The mollic epipedon is 8 to 20 inches thick.

The A horizon has hue of 10YR or 2.5Y, value of 4 or 5 dry, 2 or 3 moist, and chroma of 1 or 2 moist and dry. This horizon is mildly or moderately alkaline.

The IC horizon has hue of 10YR or 2.5Y, value of 5 or 6 dry, 4 or 5 moist, and chroma of 1 or 2 moist and dry. Mottles range from few to many and from faint to prominent. Carbonate content ranges from about 7 to 15 percent and the reaction is mildly to moderately alkaline. Stratified thin layers of variable textures are common below depth of about 24 inches.

COMPETING SERIES: These are the Foxcreek, Furniss, and Moslander (t) series. Foxcreek soils are moderately deep to sand and gravel and lack carbonate accumulation. Furniss soils are poorly drained and are noncalcareous. Moslander soils lack distinct and continuous concentrated horizons of secondary calcium carbonate above depth of 40 inches.

GEOGRAPHIC SETTING: Tonks soils are on level to very gently sloping alluvial fans and bottomlands. Elevations range from about 5,500 to 7,000 feet. The soils formed in mixed, stratified alluvium derived from a variety of igneous, metamorphic and sedimentary rocks. The soils are in a cool subhumid continental climate with annual precipitation ranging from 15 to 18 inches. The mean annual temperature is about 39 to 43 degrees F., and the mean summer temperature is about 52 to 54 degrees F. The frost free season is about 50 to 80 days.

GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Foxcreek and Furniss soils.

DRAINAGE AND PERMEABILITY: Somewhat poorly drained; slow runoff; moderately slow permeability. Some areas may be flooded occasionally.

USE AND VEGETATION: The soils are used mostly for hay and pasture. Cultivated occasionally to establish stands of clover and improved grasses. Minor acreages o oats and barley. Vegetation is mainly bluegrasses, redtop, fescues, alsike and white clovers, sedges, shrubby cinequefoil, and associated wet meadow plants.

DISTRIBUTION AND EXTENT: South eastern Idaho. The soils are inextensive.

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

SERIES ESTABLISHED: Teton County, Idaho, 1975.

REMARKS: In 2011 with the extensive revision of the Teton Area, Idaho and Wyoming soil survey the Tonks series was inactivated. The location of the Tonks OSD is now mapped and correlated to the Zohner Series

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National Cooperative Soil Survey
U.S.A.