Tarrant County consists of 898 square miles of gently sloping to level terrain with elevation ranging from 420 feet in the southeast to 960 feet in the northwest. The Trinity River is the major watercourse and flows from the northwest to the southeast across the county, with the Clear Fork and the West Fork draining the western half and other smaller tributaries draining the eastern half. Major lakes in the county include Arlington, Benbrook, Eagle Mountain, Grapevine, and Worth. Hardwoods such as American elm, pecan, and box elder are found throughout most of the county along rivers and creeks. Exposed rock formations in the area are almost exclusively of the Cretaceous period.
Mineral resources are sand, gravel, stone, and natural gas.
Rainfall averages a little more than thirty-two inches per year, and the growing season extends for 230 days. Little is known of the Indians who inhabited the area of present-day Tarrant County before the coming of European explorers in the sixteenth century. Groups thought to have been in the area were the Tonkawas and the Hasinai Caddos. By the late 1700s the Comanches, Kiowas, and Wichitas had also moved into the region. When white settlers came they clashed with the native population.