LOCATION EDDY               TX

EDDY SERIES

TAXONOMIC CLASS: Loamy-skeletal, carbonatic, thermic, shallow
Typic Ustorthents

TYPICAL PEDON: Eddy gravelly clay loam--native pasture. (Colors are for dry soil unless otherwise stated.)

A1--0 to 6 inches; light brownish gray (10YR 6/2) very gravelly clay loam, dark grayish brown (10YR 4/2) moist; strong fine granular structure; hard, firm; many fine roots; common fine pores; about 35 percent by volume of platy fragments of chalk, mostly 0.1 to 3 inches in diameter; calcareous; moderately alkaline; abrupt irregular boundary. (2 to 10 inches thick)

A2--6 to 10 inches; light brownish gray (10YR 6/2) extremely gravelly clay loam, dark grayish brown (10YR 4/2) moist; strong fine granular structure; chalk fragments range from 60 percent at top of horizon to 85 percent at bottom; many roots in upper part and few roots in the lower part; calcareous; moderately alkaline; abrupt wavy boundary. (0 to 9 inches thick)

Cr--10 to 60 inches; white (10YR 8/2) level-bedded partially cemented marine chalky limestone; about 2 on Mohs scale in the upper part grading to 3 or more on Mohs scale in the lower part.

TYPE LOCATION: Collin County, Texas; 14 miles southwest of McKinney on Texas Highway 121, and 1.3 miles by road west of its junction with Texas Highway 289, 400 feet north in pasture.

RANGE IN CHARACTERISTICS: The solum ranges from 3 to 14 inches thick over chalky limestone. The whole soil contains 35 to 60 percent by volume of chalky limestone fragments. The fragments range from very weakly cemented to strongly cemented. They are mostly 1/10 inch to 3 inches in the long axis, but some are as much as 10 inches. Some of the coarse fragments slake in water upon repeated tumbling.

The A horizon has color with hue of 7.5YR to 2.5Y, value of 3 to 6, and chroma of 2 to 6. Where moist color values and chromas are less than 3.5, the A horizon is less than 4 inches thick. The A1 horizon is very gravelly loam, very gravelly clay loam, gravelly loam, gravelly clay loam, and in some horizons thinner than 5 inches, loam and clay loam. The A2 horizon is extremely gravelly loam or extremely gravelly clay loam.

The chalky limestone C horizon ranges in hardness from about 1 to slightly less than 3 on Mohs scale, but in some pedons, it increases in hardness with depth to more than 3 on Mohs scale.

COMPETING SERIES: There are no soils in the same family. Similar soils are the Brackett, Cottonwood, Maloterre, Potter, Stephen, Talpa, and Tarrant series. Brackett soils have sola containing less than 35 percent coarse fragments and B horizons having evident soil structure, segregated calcium carbonate, and mixing by earthworms. Cottonwood and Potter soils are are in drier climates. Cottonwood soils developed in gypsum beds. Maloterre, Talpa, and Tarrant soils are all underlain by limestone having hardness exceeding 3 on Mohs scale. Talpa and Tarrant soils have mollic epipedons. Stephen soils also have mollic epipedons.

GEOGRAPHIC SETTING: These soils are on gently sloping to moderately steep uplands. Underlying rocks are predominantly of the Austin chalk geologic formation. Slope gradients are dominantly 3 to 5 percent but they range from 1 to 20 percent. The climate is moist subhumid and humid; mean annual precipitation ranges from 31 to 39 inches, Thornthwaite annual P-E indices from 48 to 76, and mean annual temperature from 64 degrees to 69 degrees F.

GEOGRAPHICALLY ASSOCIATED SOILS: These are mainly the competing Brackett and Stephen series and the Austin series. Austin soils have mollic epipedons, and sola 20 to 40 inches thick. Brackett soils occur on similar surfaces. Austin and Stephen soils occur at lower elevations.

DRAINAGE AND PERMEABILITY: Well drained; rapid to medium runoff; moderately slow permeability.

USE AND VEGETATION: Small areas are cultivated, mainly to small grains. Most of the soil is in native pastures of buffalograss, Texas grama, and annuals. Shrubs and trees, especially juniper, are common in many places.

DISTRIBUTION AND EXTENT: The known areas are in a narrow band along the western edge of the Blackland Prairie of Texas and in small areas on outcrops of marine chalks other than those of the Austin Formation. The soil is of moderate extent.

MLRA OFFICE RESPONSIBLE: Temple, Texas

SERIES ESTABLISHED: McLennan County, Texas; 1944.

REMARKS: Diagnostic horizons and features recognized in this pedon are:

Ochric epipedon - 0 to 10 inches.

Paralithic content - occurs at 10 inches, interface of soil and chalky limestone.