LOCATION TOPIA TXEstablished Series
TAXONOMIC CLASS: Very-fine, mixed, superactive, thermic Vertic Argiustolls
TYPICAL PEDON: Topia clay--rangeland. (Colors are for dry soil unless otherwise stated.)
A--0 to 7 inches; very dark gray (10YR 3/1) clay, black (10YR 2/1) moist; moderate fine and medium subangular blocky and granular structure; very hard, firm; very sticky and plastic; many fine roots; few fine pores and old root channels; neutral; clear smooth boundary. (4 to 10 inches thick)
Bt1--7 to 12 inches; dark reddish brown (5YR 3/2) clay; dark reddish brown (5YR 2/2) moist; moderate fine and very fine angular blocky structure; extremely hard, very firm, very sticky and plastic; many fine roots; clay films on peds; dark organic staining on few peds; few cracks partially filled with A material; few pockets of redder clay; neutral; gradual wavy boundary. (5 to 17 inches thick)
Bt2--12 to 22 inches; dark reddish brown (5YR 3/3) clay, dark reddish brown (5YR 3/3) moist; moderate medium and fine angular blocky structure; extremely hard, very firm, very sticky and plastic; common fine roots; clay films on peds; distinct shiny pressure faces; dark organic stains on few peds; few vertical streaks one-inch wide of darker clay; few pockets of red clay; few fine limestone fragments; neutral; gradual wavy boundary. (3 to 13 inches thick)
Bt3--22 to 27 inches; reddish brown (5YR 4/3) clay, dark reddish brown (5YR 3/3) moist; weak fine and medium angular blocky structure very hard, very firm, sticky and plastic; few fine roots; patchy clay films on peds; few distinct pressure faces; dark organic stains on few peds; few vertical streaks of darker clay; estimated 2 percent by volume of 1 to 2 mm weakly cemented limestone fragments; few larger fragments; strongly effervescent; moderately alkaline; clear wavy boundary. (0 to 9 inches thick)
Bt4--27 to 30 inches; reddish brown (5YR 4/4) very gravelly clay, dark reddish brown (5YR 3/4) moist; weak fine and medium subangular blocky structure; very hard, firm; few fine roots; estimated 50 percent by volume of weakly cemented limestone pebbles; many of the fragments are coated with clay; violently effervescent; moderately alkaline; abrupt wavy boundary. (0 to 8 inches thick)
2Cr--30 to 48 inches; very pale brown (10YR 7/4) and yellow (10YR 7/6) weakly cemented consolidated limestone bedrock; streaks and splotches of reddish yellow (7.5YR 6/6) and (5YR 6/6); upper one-half inch is slightly harder than that below.
TYPE LOCATION: Uvalde County, Texas; 1.4 miles west of Utopia on Farm to Market Road 1050, 0.75 mile south and west on county road, 400 feet south in rangeland, 285 feet southwest of old house and 80 feet west of post oak tree.
RANGE IN CHARACTERISTICS: Thickness of the solum and depth to limestone bedrock ranges from 21 to 40 inches. Coarse fragments in the control section range from a few to 15 percent by volume. Cracks up to 2 inches wide at the soil surface extend to 20 inches or more when the soil is dry and are 1/4 to 1/2 inch wide at 20 inches. The mollic epipedon ranges from 10 inches thick in some pedons to the entire thickness of the solum in others.
The A horizon is very dark gray to dark reddish gray in a hue of 10YR through 5YR, chroma of 3 or 4 and value of 1 or 2. Texture is clay loam or clay. Coarse fragments range from few to 15 percent by volume of limestone and chert. Reaction ranges from slightly acid to slightly alkaline.
The Bt1 horizon is brown to dark reddish brown in a hue of 5YR or 7.5YR, values of 3 or 4 and chroma or 2 or 3. Texture of the Bt horizon is a clay, with the upper 20 inches of the Bt horizon ranging from 60 to 75 percent clay. Coarse fragments range from few to 15 percent by volume of limestone and chert. Reaction ranges from slightly acid to slightly alkaline.
The Bt2 horizon is dark reddish brown to brown in a hue of 2.5YR, 5YR or 7.5YR , value of 3 or 4 and chroma of 3 or 4. Texture is clay loam or clay. The Bt1 and Bt2 horizons are slightly acid to slightly alkaline.
The Bt3 and Bt4 horizons, where present, have hue of 2.5YR or 5YR, value of 4 or 5 and chroma of 3 or 4. Coarse fragments range from a few to 60 percent by volume. Texture is clay, gravelly clay or very gravelly clay. Reaction is slightly alkaline or moderately alkaline. Secondary carbonates range from very thin coatings on the limestone to 10 percent by volume in the lower part of the Bt horizon.
The 2Cr horizon is interbedded chalk, marl, weakly consolidated limestone and strongly cemented or indurated limestone.
COMPETING SERIES: There are no other soils in this family. Similar series include the Anhalt, Bexar, Crawford, Durant, Lindy, Rumple, Scullin, and Speck series. Bexar and Lindy soils lack a mollic epipedon. Crawford soils have slickensides hard bedrock strata and lack argillic horizons. Durant soils have less than 60 percent clay in the control section. Rumple sols have more than 35 percent coarse fragments in the control section. Scullin soils have less than 60 percent clay in the argillic horizon. Speck soils are less than 20 inches deep over limestone. Anhalt soils have slickensides.
GEOGRAPHIC SETTING: Topia soils are on smooth to gently undulating uplands. Slopes are mostly less than 2 percent but range up to 5. The soil formed in clayey residuum of limestone bedrock. The mean annual precipitation ranges from 22 to 32 inches, Thornthwaite annual P-E indices are about 32 to 48, and mean annual air temperature ranges from 64 degrees to 70 degrees F. Frost free days range from 235 to 255 days. Elevation ranges from 1000 to 2000 feet.
GEOGRAPHICALLY ASSOCIATED SOILS: These include the competing Bexar, Crawford, Rumple, Scullin, and Speck series, as well as the Brackett, Denton, Eckrant, Kavett, Pratley, San Saba, and Tarrant series. Brackett, Denton, Eckrant, Kavett, San Saba, and Tarrant soils lack argillic horizons. In addition, Brackett, Eckrant, Kavett, and Tarrant soils are less than 20 inches deep. Pratley soils are calcareous throughout and have less than 60 percent clay in the control section. San Saba soils have intersecting slickensides.
DRAINAGE AND PERMEABILITY: Well drained. Runoff is low on 0 to 1 percent slopes, medium on 1 to 3 percent slopes and high on 3 to 5 percent slopes. Permeability is very slow.
USE AND VEGETATION: Mainly rangeland, but a few areas are used for growing small grains and grain sorghums. Present vegetation includes live oak, cedar, post oak, Texas persimmon, curlymesquite, Texas wintergrass, fall witchgrass, sideoats grama, little bluestem, and Indiangrass.
DISTRIBUTION AND EXTENT: Edwards Plateau and Grand Prairie of Texas. Topia soils are of moderate extent with about 13,000 acres.
MLRA OFFICE RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Uvalde County, Texas; 1970.
REMARKS: Topia soils were formerly included in the Crawford series. Diagnostic horizons and feature recognized in this pedon are:
Mollic epipedon 0 to 27 inches.
Argillic horizon 7 to 30 inches.
Paralithic Contact at 30 inches.