Most of the county is on the Edwards Pleateau except for the northeastern corner, which is in the Llano River basin. The primary soils are generally shallow and clayey and not particularly suited to intensive agriculture. The soils in the bottomlands along the Pedernales River and some major creeks are deeper and loamier and better for crops, while the soils in northeastern Gillespie County are generally shallow and loamy. The terrain features plateaus and limestone hills broken by the Pedernales River, with an elevation ranging from 1,100 to 2,250 feet above sea level and averaging 1,747 feet above sea level. The soils on Gillespie County's limestone hills support growths of live oak, shin oak, and other browse plants, as well as grasses and forbs well-suited for grazing. The deeper soils in the valleys and plains produce a true prairie of medium and tall grasses mixed with forbs and woody plants. Some 573,000 acres (85 percent of the agricultural land in the county) is rangeland, which constitutes the county's major renewable resource.