LOCATION CONA TXEstablished Series
TAXONOMIC CLASS: Fine, mixed, active, thermic Udic Paleustalfs
TYPICAL PEDON: Cona sandy loam,stony--wooded pasture. (Colors are for dry soil unless otherwise stated.)
A--0 to 4 inches; brown (10YR 5/3) sandy loam; brown (10YR 4/3) moist; weak very fine subangular blocky structure; soft, very friable; many fine roots; about 5 percent by volume of quartz pebbles; surface has about 15 percent cover of partially rounded conglomerate sandstone fragments and stones 3 to 20 inches across long axis and few stones embedded in horizon; neutral; clear wavy boundary. (2 to 5 inches thick)
E--4 to 8 inches; very pale brown (10YR 7/4) gravelly sandy loam; light yellowish brown (10YR 6/4) moist; single grain; soft, very friable; many fine roots; about 15 percent by volume of quartz pebbles and about 25 percent by volume of partially rounded conglomerate sandstone fragments and stones; neutral; abrupt wavy boundary. (1 to 5 inches thick)
Bt1--8 to 17 inches; red (2.5YR 4/6) sandy clay, dark red (2.5YR 3/6) moist; common medium distinct mottles of reddish yellow (7.5YR 6/6); moderate medium subangular blocky structure; very hard, very firm; common fine roots; thin continuous clay films; few pockets of clean sand grains; about 5 to 10 percent by volume of quartz pebbles; strongly acid; clear wavy boundary. (5 to 14 inches thick)
Bt2--17 to 27 inches; mottled red (2.5YR 4/6) and reddish yellow (7.5YR 6/6) clay; moderate medium blocky structure; very hard, very firm; common fine roots; about 1 percent quartz pebbles; thin continuous clay films; few pockets of clean sand grains; strongly acid; gradual wavy boundary. (10 to 18 inches thick)
BCt--27 to 33 inches; pale yellow (2.5Y 7/4) clay, common fine and medium mottles of red (2.5YR 4/8), reddish yellow (7.5YR 6/6); common fine and medium shale fragments that are light gray (2.5Y 7/2); moderate medium blocky structure; very hard, very firm; few fine roots; about 1 percent quartz pebbles; thin patchy clay films; medium acid; gradual wavy boundary. (0 to 8 inches thick)
C--33 to 45 inches; light gray (2.5Y 7/2) clay and soft shale; common fine and medium distinct mottles of red (2.5YR 4/8) and strong brown (7.5YR 5/6); weak platy and blocky structure; retains part of apparent original rock structure; very hard, very firm; few fine tree roots; mildly alkaline.
TYPE LOCATION: Montague County, Texas; about 5 miles southeast of Bowie; 0.3 mile south of Fruitland on U.S. Highway 287 and 81 to road intersection, 0.4 mile northeast and 0.1 mile southeast of intersection, and 10 feet west of road.
RANGE IN CHARACTERISTICS: Solum thickness ranges from 20 to 40 inches. Base saturation ranges from 75 to 100 percent in some part of the argillic horizon. The clay content of the control section ranges from 35 to 45 percent. Fragments of siliceous pebbles and sandstone conglomerate or sandstone cover 2 to 20 percent of the soil surface. These fragments range from about 3 to 48 inches across the long axis. Most of the fragments are 10 to about 30 inches across.
The A horizon has colors in hue of 7.5YR or 10YR, value of 4 or 5, and chroma of 2 or 3. The E horizon has colors with 1 to 2 units of value or chroma greater than the A horizon. Siliceous and sandstone pebbles range from a few to 35 percent by volume. Also, fragments of conglomerate and sandstone that range from 3 to 48 inches across make up 5 to 30 percent by volume of these horizons. Texture of the fine earth fraction is fine sandy loam or sandy loam. The reaction ranges from slightly acid to mildly alkaline.
The Bt horizon has hue of 2.5YR to 7.5YR, value of 4 to 6, and chroma of 6 or 8. The Bt2 or lower part of the Bt horizon is mottled with these colors in some pedons. Grayish fragments of weathered shaley materials are also in the lower part of some pedons. Texture is clay, sandy clay, or clay loam. Siliceous or sandstone pebbles, cobbles, and stones range from none to 12 percent by volume. However, the upper part of the Bt1 horizon contains up to 35 percent by volume pebbles and cobbles in some pedons. The reaction is strongly acid or moderately acid.
The BCt and C horizons are in shades of yellow, brown, or gray with or without mottles of these colors or reddish mottles. Texture is clay, or sandy clay or is shale with or without strata of loamy materials. Reaction ranges from moderately acid to mildly alkaline. Calcium carbonate concretions range from none to a few in some pedons.
COMPETING SERIES: These are the Callisburg, Chigley, Edge, Hamby, Margie, Minwells, Truce, Voca and Windthorst soils in the same family. Callisburg soils have sola thicker than 60 inches and lack colors with hue 5YR or redder. Chigley soils typically have a gravelly Bt horizon and are underlain by a lithic contact of conglomerate. Hamby soils are more alkaline in the upper Bt horizon and have a thicker sola. Margie soils have sola more than 60 inches thick and lack stony surface layers. Minwells soils are underlain by beds of sand and gravel. They also lack stony surfaces. Truce soils are more alkaline in the upper Bt horizons and typically have calcareous lower layers. Voca soils developed in residuum from weathered granite and have a paralithic contact of granitic materials at a depth of 40 to 60 inches. Edge and Windthorst soils have sola 40 to 60 inches thick and lack stony surface layers.
GEOGRAPHIC SETTING: Cona soils are on erosional uplands. Soil areas are convex, with slope gradients of 3 to 25 percent but are dominantly 5 to 15 percent. The soils formed in sediments such as that of the basal Trinity Formation which includes clays, shales, and quartz conglomerates of Lower Cretaceous age. The climate is dry subhumid. The mean annual temperature ranges from 64 to 66 degrees F., and the average annual rainfall is about 28 to 32 inches. Frost free period is 220 to 230 days and elevation ranges from 900 to 1200 feet. The Thornthwaite annual P-E index ranges from 44 to 50.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the competing Truce and Windthorst series and the Bonti, Chaney, and Selden series. Bonti soils are underlain by a lithic contact of sandstone. Chaney and Selden soils are members of an Aquic subgroup. Bonti soils are on higher positions. The other soils are below the Cona soils. However, Windthorst soils are also on similar positions.
DRAINAGE AND PERMEABILITY: Well drained; rapid runoff; slow permeability; slow internal drainage.
USE AND VEGETATION: Mostly used for rangeland. Vegetation is noncommercial hardwood forest of post oak and blackjack oak. Native grasses include little bluestem and sideoats grama.
DISTRIBUTION AND EXTENT: North-central Texas and possibly Oklahoma. The series is of moderate extent.
MLRA SOIL SURVEY REGIONAL OFFICE (MO) RESPONSIBLE: Temple, Texas
SERIES ESTABLISHED: Montague County, Texas; 1975.
REMARKS: These soils were formerly included in the Windthorst series.
Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - the zone from 0 to 8 inches.
Agrillic horizons - the layer from 8 to 33 inches.
Paleustalf feature - abrupt textured change at 8 inches.
ADDITIONAL DATA: NSSL data on type location in Montague County, Texas (S81TX-337-001).