LOCATION TOMAST OK+AREstablished Series
TAXONOMIC CLASS: Fine-silty, siliceous, active, thermic Aeric Paleaquults
TYPICAL PEDON: Tomast silt loam - forested.
(Colors are for moist soil unless otherwise stated.)
01-- 3/4-0 inches, decaying forest litter.
A1-- 0-2 inches, very dark grayish brown (10YR 3/2) silt loam; weak medium granular structure; friable; many roots; medium acid; clear wavy boundary. (2 to 6 inches thick)
A2-- 2-6 inches, grayish brown (10YR 5/2) silt loam; few fine distinct yellowish brown (10YR 5/6) mottles; weak fine
granular structure; friable; many roots; strongly acid; clear wavy boundary. (3 to 6 inches thick)
B1t-- 6-22 inches, yellowish red (5YR 5/6) silty clay
loam; few fine distinct mottles of light brownish gray (10YR 6/2) weak medium subangular blocky structure; friable; patchy clay
films on surfaces of peds; very strongly acid; gradual smooth boundary. (10 to 20 inches thick)
B21t-- 22-28 inches, strong brown (7.5YR 5/6) silty clay loam; many medium prominent mottles of gray (10YR 6/1) and a few
fine and medium distinct mottles of yellowish red (5YR 4/6);
moderate medium blocky structure; firm; thin continuous clay films
on surfaces of peds; very strongly acid; gradual smooth boundary.
(6 to 24 inches thick)
B22tg-- 28-48 inches, gray (10YR 6/1) silty clay loam; many medium prominent red (2.5YR 4/6) and distinct yellowish brown
(10YR 5/6) mottles; strong medium blocky structure; firm; thin continuous clay films on surfaces of peds; very strongly acid; gradual smooth boundary. (15 to 45 inches thick)
B23tg-- 48-65 inches, gray (10YR 6/1) silty clay; many
medium prominent red (2.5YR 5/6) and a few fine distinct yellowish brown (10YR 5/6) mottles; weak medium blocky structure; firm;
patchy clay films on surfaces of peds; few silt coatings on
vertical faces of some peds; very strongly acid; gradual smooth boundary. (0 to 20 inches thick)
B3g-- 65-80 inches, light brownish gray (10YR 6/2) silty clay; common medium distinct mottles of olive brown (2.5Y 4/3) and
a few fine distinct mottles of yellowish brown (10YR 5/6) weak
medium blocky structure; very firm; few slickensides and shiny
faces on peds; very strongly acid; gradual smooth boundary. (10
to 18 inches thick)
Cg-- 80-90 inches, light brownish gray (10YR 6/2) heavy silty clay loam; yellowish brown (10YR 5/6) laminations; massive; evident very fine laminations showing rock structure; very
strongly acid.
TYPE LOCATION: McCurtain County, Oklahoma; about 400 feet north
and 2350 feet west of the southeast corner sec. 4, T. 9 S., R. 27
E.
RANGE IN CHARACTERISTICS: Solum thickness exceeds 60 inches. Reaction ranges from very strongly acid to slightly acid in the A1 horizon and strongly acid to very strongly acid below. Within the control section, clay content ranges from 27 to 35 percent and the silt content is more than 30 percent.
The A1 horizon is very dark grayish brown (10YR 3/2) or dark
grayish brown (10YR 4/2). The A2 horizon is brown (10YR 4/3,
5/3), grayish brown (10YR 5/2), pale brown (10YR 6/3), or light yellowish brown (10YR 6/4). The A horizon is loam or silt loam.
The B1t horizon is yellowish red (5YR 5/6) or strong brown (7.5YR 5/6). It is clay loam or silty clay loam. The B21t horizon is strong brown (7.5YR 5/6), brown (7.5YR 5/2, 5/4), or reddish
yellow (7.5YR 6/6, 6/8) with mottles in shades of gray and yellow. It is silty clay loam or clay loam. The Btg horizons are gray
(10YR 6/1) or light brownish gray (10YR 6/2) with mottles in
shades of red, brown, or yellow. They are silty clay loam, silty clay, or clay. Slickensides are present below 60 inches in some pedons.
The Cg horizon is coarsely mottled in shades of red, brown, or
gray.
COMPETING SERIES: These are the Coxville,
Dunbar, Exum, Falkner, Felker, Grady, Grantham, Kinta, Kullit, Lenoir, Muskogee, Nahunta, Rains, Rufe, Tiak, and Trebloc series. Coxville, Grady, Grantham, Rains, Rufe, and Trebloc soils lack chromas of 3 or more within the upper Bt horizon. In addition,
the Coxville and Grady soils have more than 35 percent clay in the control section. The Grantham and Rains soils have more than 15 percent particles coarser than very fine sand in the control
section. The Dunbar, Kinta, and Lenoir
soils have more than 35 percent clay in the control section.
Falkner and Muskogee soils have a base saturation of 35 percent or more at 50 inches below the top of the argillic horizon. In addition, Muskogee soils have mixed mineralogy. The Exum, Felker, Kullit, and Tiak soils lack dominant colors of chroma 2 or less within the B horizon. In addition, the Kullit soils have more
than 15 percent particles coarser than very fine sand. Tiak soils contain more than 35 percent clay in the control section. Nahunta soils lack hues redder than 10YR as matrix colors in the Bt
horizons. In addition, they contain a few plinthic nodules in the lower part.
GEOGRAPHIC SETTING: Tomast soils occur on nearly level and very gently sloping uplands. Slopes are commonly less than 2 percent. The regolith is loamy and clayey sediments. Mean annual air
temperature ranges from 62 degrees to 65 degrees F. Mean annual precipitation ranges from 40 to 50 inches. Tomast soils receive
an average total rainfall of 8.69 inches during the months of July through September and the average probability of receiving 1 inch
of moisture is 1.3 days per month.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Felker, Kullit, and Kinta series.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; slow runoff; slow permeability.
USE AND VEGETATION: A few areas have been cleared and are used
for pasture. The major use is forests. Native vegetation is loblolly pine, shortleaf pine, sweetgum, and other hardwoods.
DISTRIBUTION AND EXTENT: Extreme southeastern Oklahoma and
possibly Arkansas, Louisiana, and Texas. The series is of
moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: McCurtain County, Oklahoma; 1970.
REMARKS: The Tomast soils would have been classified in the Low-Humic Gley great soils group.