Slope gradients are 0 to 3 percent. The soils formed in local, loamy alluvium. Mean annual temperature is 64 to 67 degrees F., average annual precipitation is 26 to 40 inches, and Thornthwaite P-E indices are 40 to 64. These are the competing Cisco and Duffau , and the Bosque , Nimrod , Pedernales , and Windthorst series. Cisco and Duffau soils are higher in the landscape on stream divides and along upland drainageways.
Bosque soils have mollic epipedons and are lower in the landscape on flood plains.
Nimrod soils have sandy epipedons 20 to 40 inches thick and are higher in the landscape on stream divides and low ridges. Pedernales and Windthorst soils have reddish clayey argillic horizons and are higher in the landscape on hillsides and stream divides. Most of May soils are in positions that receive extra water from adjacent higher areas. Native vegetation is mid and tall grasses and post oak, live oak, and mesquite trees. In the Cross Timbers, Central Rolling Red Prairies and fringe areas of the Grand Prairie in central Texas.