LOCATION TOMTY MTEstablished Series
TAXONOMIC CLASS: Fine, smectitic, frigid Aquic Hapluderts
TYPICAL PEDON: Tomty silty clay, forested. (Colors are for dry soil unless otherwise noted.)
A--0 to 6 inches; black (10YR 2/1) silty clay, black (10YR 2/1) moist; strong very fine granular structure in upper 2 inches and strong fine and very fine subangular blocky structure below; very hard, firm, moderately sticky and moderately plastic; many fine, very fine, medium, and coarse roots; less than 1 percent limestone pebbles; slightly effervescent; neutral (pH 7.1); clear wavy boundary. (4 to 8 inches thick)
Bk1--6 to 13 inches; very dark gray (10YR 3/1) silty clay, very dark gray (10YR 3/1) moist; strong fine and very fine subangular blocky structure; extremely hard, firm, moderately sticky and very plastic; many very fine, fine, medium, and coarse roots; common fine and very fine pores; less than 1 percent limestone pebbles; few fine and medium soft masses of segregated lime; slightly effervescent; slightly alkaline (pH 7.5); clear wavy boundary. (6 to 10 inches thick)
Bkss2--13 to 18 inches; dark gray (10YR 4/1) clay, very dark gray (10YR 3/1) moist; strong fine and very fine subangular blocky structure; extremely hard, firm, moderately sticky and very plastic; common very fine, fine, medium, and coarse roots; common fine and very fine pores; common intersecting slickensides; less than 1 percent limestone pebbles; few fine and medium soft masses of segregated lime; strongly effervescent; slightly alkaline (pH 7.6); abrupt smooth boundary. (8 to 15 inches thick)
Bkss3--18 to 30 inches; light gray (10YR 7/1) silty clay, gray (10YR 5/1) moist; many medium and fine distinct light yellowish brown (10YR 6/4) and brownish yellow (10YR 6/6) redox concentrations; moderate medium and fine angular blocky structure; extremely hard, very firm, moderately sticky and very plastic; common very fine, fine, medium, and coarse roots; common fine and very fine pores; few intersecting slickensides; few fine soft masses of segregated lime; strongly effervescent; slightly alkaline (pH 7.7); clear wavy boundary. (10 to 20 inches thick)
Cg1--30 to 41 inches; gray (N 5/) clay, dark gray (N 4/0) moist; common fine distinct yellowish red (5YR 5/6) and strong brown (7.5YR 5/6) redox concentrations; weak coarse angular blocky structure; extremely hard, very firm, moderately sticky and very plastic; few very fine, medium, and coarse roots; common fine and very fine pores; strongly effervescent; slightly alkaline (pH 7.7); clear wavy boundary. (10 to 15 inches thick)
Cg2--41 to 50 inches; gray (N 5/0) silty clay, dark gray (N 4/ ) moist; common medium and large distinct light olive brown (2.5Y 5/6) redox concentrations; weak coarse angular blocky structure; extremely hard, firm, moderately sticky and moderately plastic; few fine, very fine, medium, and coarse roots; common fine and very fine pores; strongly effervescent; slightly alkaline (pH 7.6) diffuse wavy boundary. (9 to 15 inches thick)
Cg3--50 to 60 inches; light gray (5Y 7/1) silty clay, gray (5Y 5/1) moist; many medium, distinct, light olive brown (2.5Y 5/4) redox concentrations; massive; extremely hard, firm, moderately sticky and moderately plastic; less than 1 percent limestone pebbles and cobbles; strongly effervescent; slightly alkaline (pH 7.6); abrupt boundary.
TYPE LOCATION: Fergus County, Montana; 530 meters south and 90 meters east of the NW corner of sec. 23, T. 13 N., R. 19 E.
RANGE IN CHARACTERISTICS:
Soil temperature: 41 to 45 degrees F.
Rock fragments: few limestone or shale pebbles in the A, B, and C horizons
Depth to k horizon: 4 to 9 inches
Depth to water table: 12 to 24 inches
A horizon
Hue: 10YR
Value, dry: 2 or 3
Value, moist: 2 or 3
Chroma: 1
Texture: silty clay loam, silty clay, or clay
Clay content: 30 to 55 percent
Rock fragments: 0 to trace pebbles
Reaction: pH 6.1 to 7.8
Bk1 and Bk2 horizon
Hue: 10YR
Value, dry: 3 or 4
Value, moist: 3 or 4
Chroma: 1
Texture: silty clay or clay
Clay content: 40 to 60 percent
Slickensides: many or common
Rock fragments: 0 to 5 percent pebbles
Calcium carbonate equivalent: 5 to 10 percent
Reaction: pH 7.4 to 8.4
Bk3 horizon
Hue: 10YR or 2.5Y
Value, dry: 5 to 7
Value, moist: 4 or 5
Chroma: 4 to 6
Texture: silty clay or clay
Clay content: 40 to 60 percent
Slickensides: few or common
Rock fragments: 0 to 5 percent pebbles
Calcium carbonate equivalent: 5 to 10 percent
Reaction: pH 7.4 to 8.4
Cg horizon
Hue: 2.5Y, 5Y, or N
Value, dry: 5, 6, or 7
Value, moist: 4 or 5
Chroma: 4 to 6
Texture: silty clay or clay
Clay content: 40 to 60 percent
Rock fragments: 0 to 15 percent pebbles
Reaction: pH 7.4 to 8.4
COMPETING SERIES: These are the Audubon and Hattie series. The Audubon soils have 20 to 35 percent calcium carbonate equivalent in the Bkss horizon. The Hattie soils have 15 to 30 percent calcium carbonate equivalent in the Bkss horizon.
GEOGRAPHIC SETTING: Tomty soils are on foot slopes in uplands. Elevations are 4,600 to 5,500 feet. Tomty soils formed in colluvium derived from clay shale. The climate is cool, with long cold winters, moist springs, and warm summers. Mean annual temperature is 39 to 43 degrees F. Mean annual precipitation is 20 to 30 inches. The growing season is 50 to 90 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are Castle, Kildor, Whitecow, and Tibs series. All of these soils are well drained.
DRAINAGE AND PERMEABILITY: Poorly drained; medium to very rapid runoff; very slow permeability.
USE AND VEGETATION: Tomty soils are used mainly for woodland and range, but are also used for hayland. Overstory is quaking aspen, and understory is scouler silene, lupine, blue wildrye, Oregongrape, Saskatoon serviceberry, common snowberry, russet buffaloberry, heartleaf arnica, and mountain sweetroot.
DISTRIBUTION AND EXTENT: Central Montana. Tomty soils are not extensive.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana
SERIES ESTABLISHED: Fergus County, Montana, 1970.