LOCATION TOPHAT ID+MT

Established Series
Rev. JFD-JJU-RJS
09/2011

TOPHAT SERIES

The Tophat series consists of very deep, well drained soils that formed in slope alluvium, colluvium or slide deposits derived from mixed sources. These soils are on hills, mountains, ridges and landslides. Slopes are 15 to 50 percent. Mean annual precipitation is about 24 inches, and mean annual air temperature is about 39 degrees F.

TAXONOMIC CLASS: Fine, mixed, superactive Pachic Argicryolls

TYPICAL PEDON: Tophat cobbly loam, on a 47 percent slope with east aspect at 6,000 feet elevation, in a mountain big sagebrush/ bluebunch wheatgrass community, in rangeland (colors are for dry soil unless otherwise noted).

A--0 to 7 inches; very dark grayish brown (10YR 3/2) cobbly loam, very dark brown (10YR 2/2) moist; moderate medium granular structure parting to weak very fine granular; slightly hard, friable, slightly sticky and slightly plastic; many very fine and fine, and common medium roots; many very fine and common fine irregular pores; 10 percent gravel and 10 percent cobbles; neutral (pH 7.0); abrupt smooth boundary. (4 to 12 inches thick)

ABt--7 to 17 inches; reddish gray (5YR 5/2) cobbly clay loam, dark reddish brown (5YR 3/2) moist; moderate medium subangular blocky structure parting to moderate medium granular; hard, firm, moderately sticky and moderately plastic; common very fine, fine and medium roots; many very fine tubular pores, and common fine irregular pores; few faint dark reddish brown (5YR 3/2) moist clay films on faces of peds; 10 percent gravel and 15 percent cobbles; slightly acid (pH 6.5); clear smooth boundary. (0 to 12 inches thick)

Bt1--17 to 28 inches; reddish brown (5YR 5/3) cobbly clay loam, dark reddish brown (5YR 3/3) moist; strong medium subangular blocky structure parting to strong very fine subangular blocky; hard, firm, moderately sticky and very plastic; few very fine, fine and medium roots; common very fine and few fine tubular pores; many faint dark reddish brown (5YR 3/3) moist clay films on faces of peds, and few distinct dark reddish brown (5YR 3/3) moist clay films lining of pores; 10 percent gravel and 15 percent cobbles; slightly acid (pH 6.5); clear smooth boundary. (5 to 15 inches thick)

Bt2--28 to 34 inches; reddish brown (5YR 5/3) cobbly clay loam, dark reddish brown (5YR 3/3) moist; strong medium subangular blocky structure; very hard, firm, moderately sticky and very plastic; few very fine, fine and medium roots; common very fine and few fine tubular pores; common distinct dark reddish brown (5YR 3/3) moist clay films on faces of peds and lining of pores; 10 percent gravel and 20 percent cobbles; slightly acid (pH 6.5); clear smooth boundary. (5 to 15 inches thick)

Bt3--34 to 45 inches; reddish brown (5YR 5/3) cobbly silty clay loam, weak red (2.5YR 4/2) moist; moderate coarse prismatic structure parting to moderate coarse subangular blocky; very hard, very firm, moderately sticky and very plastic; few very fine and medium roots; common very fine tubular pores; common distinct weak red (2.5YR 4/2) moist clay films on faces of peds and lining of pores; 10 percent gravel and 20 percent cobbles; slightly acid (pH 6.5); gradual smooth boundary. (5 to 30 inches thick)

Bt4-- 45 to 60 inches; reddish brown (5YR 5/3) very cobbly silty clay loam, weak red (2.5YR 4/2) moist; moderate very coarse prismatic structure parting to moderate very coarse subangular blocky; very hard, very firm, moderately sticky and very plastic; few very fine and medium roots; common very fine tubular pores; common distinct weak red (2.5YR 4/2) moist clay films on faces of peds and lining of pores; 5 percent gravel, 20 percent cobbles, and 10 percent stones; slightly acid (pH 6.5).

TYPE LOCATION: Bonneville County, Idaho, about 12.5 miles south and 4.5 miles east of Swan Valley; about 1,200 feet east and 1,500 feet south of the northwest corner of section 1, T. 2S, R 44E; Latitude- 43 degrees North, 16 minutes, 34 seconds; Longitude - 111 degrees West, 14 minutes, 50 seconds.

RANGE IN CHARACTERISTICS:
Mean annual soil temperature - 38 to 42 degrees F.
Mean summer soil temperature - 50 to 54 degrees F.
Mollic epipedon thickness - 16 to 40 inches
Depth to argillic horizon - 4 to 20 inches
Clay content in particle-size control section (weighted average) - 35 to 50 percent.
Rock fragments in particle-size control section (weighted average) - 0 to 35 percent.

A horizon
Hue: 7.5YR or 10YR; dry or moist
Value: 3 to 5 dry; 2 or 3 moist
Chroma: 2 or 3; dry or moist
Clay content: 20 to 27 percent
Rock fragments: 5 to 35 percent--0 to 15 percent gravel, 0 to 20 percent cobbles, 0 to 5 percent stones
Reaction: pH 6.6 to 7.3

ABt horizon
Hue: 2.5YR, 5YR, 7.5YR or 10YR; dry or moist
Value: 4 or 5 dry; 2 or 3 moist
Chroma: 2 or 3; dry or moist
Texture: silty clay loam or clay loam
Clay content: 27 to 40 percent
Rock fragment content: 0 to 35 percent--0 to 15 percent gravel, 0 to 20 percent cobbles, 0 to 5 percent stones
Reaction: pH 6.1 to 7.3

Bt1, Bt2 horizons
Hue: 2.5YR, 5YR, 7.5YR or 10YR; dry or moist
Value: 5 or 6 dry; 3 to 5 moist
Chroma: 2 to 4; dry or moist
Texture: clay, silty clay loam or clay loam
Clay content: 35 to 50 percent
Rock fragments: 0 to 35 percent--0 to 15 percent gravel, 0 to 20 percent cobbles, 0 to 5 percent stones
Reaction: pH 6.1 to 7.3

Bt3, Bt4 horizons
Hue: 2.5YR, 5YR, 7.5YR or 10YR; dry or moist
Value: 4 to 7 dry; 4 to 6 moist
Chroma: 2 to 4; dry or moist
Texture: silty clay loam or clay loam
Clay content: 27 to 40 percent
Rock fragments: 0 to 60 percent--0 to 15 percent gravel, 0 to 30 percent cobbles, 0 to 20 percent stones
Reaction: pH 5.6 to 7.3

COMPETING SERIES:
Cratermo (ID) - are moderately deep to a lithic contact
Hammersley (OR) - are deep to a paralithic contact
Lingshire (MT) - are moderately deep to a paralithic contact
Teedown (CO) - the wettest months are July and August

GEOGRAPHIC SETTING:
Landform - hills, mountains, ridges and landslides
Elevation - 5,600 to 8,500 feet
Slope - 15 to 50 percent
Parent material - slope alluvium, colluvium or slide deposits derived from mixed sources
Climate - winters are moist and cool, summers are warm and dry. A winter snowpack of 2 to 4 feet in depth and lasting through April is common.
Mean annual precipitation - 20 to 35 inches
Mean annual air temperature - 36 to 40 degrees F.
Frost free period - 30 to 70 days

GEOGRAPHICALLY ASSOCIATED SOILS: These are the Etnass, Jumpstart, Nearl, Quirt and Sedgway series. Etnass soils are on nearby ridges, summits and sideslopes. They formed in residuum from shale, have intersecting slickensides and cracks, and are 10 to 40 inches deep to carbonates. Jumpstart soils are on nearby sideslopes. They have a forest litter horizon and lack a mollic epipedon. Nearl soils are on nearby basins. They have a forest litter horizon, lack an argillic horizon, and have a mollic epipedon less than 16 inches thick. Quirt soils are on nearby sideslopes. They formed in residuum from shale, have a mollic epipedon less that 16 inches thick, and are 15 to 30 inches deep to carbonates. Sedgway soils are on nearby ridges, summits and sideslopes. They average less than 35 percent clay in the particle-size control section and have a mollic epipedon less than 16 inches thick.

DRAINAGE AND PERMEABILITY: Well drained; slow permeability.

USE AND VEGETATION: Tophat soils are used for livestock grazing, recreation and wildlife habitat. These soils commonly support communities that have a shrub layer of mountain big sagebrush, spike big sagebrush or subalpine big sagebrush, with an herbaceous layer dominated by California brome, slender wheatgrass or bluebunch wheatgrass.

DISTRIBUTION AND EXTENT: They are of moderate extent in southeastern Idaho and southwestern Montana. MLRAs - 43B, 46.

MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Bozeman, Montana.

SERIES ESTABLISHED: Targhee National Forest, Bonneville County, Idaho, 1997.

REMARKS: Diagnostic horizons and features recognized in this pedon are:
Mollic epipedon - from 0 to 34 inches (A, ABt, Bt1, Bt2 horizons)
Argillic horizon - from 7 to 60 inches (ABt Bt1, Bt2, Bt3, Bt4 horizons)
Particle-size control section - from 7 to 27 inches (ABt, part of Bt1 horizons)

Tophat soils have a cryic temperature regime and an udic moisture regime.

ADDITIONAL DATA: Primary Characterization Data (06/27/89) NSSL, Lincoln, NE. Client-Assigned Laboratory Number S88ID-019-005; Project File numbers 88P 148; Laboratory-Assigned Numbers: Pedon 88P 836, Samples 88P4373-4377.

National Cooperative Soil Survey
U.S.A.