Geologically speaking, the Piedmont region of Georgia features crystalline rocks, metamorphosed sedimentary rocks from the late Precambrian Period to early Paleozoic Period, and a thick layer of decomposed rock called saprolite, which is the red clay of Georgia. Topographically, the Piedmont consists of low hills and narrow valleys and contains numerous rivers and forests made up of mostly oak and hickory trees. Pine trees are relatively uncommon. The Piedmont is Georgia’s second-largest geographical region and contains its highest population.
The Piedmont is a plateau that spreads from New Jersey in the north to central Alabama in the south. Most of the soils are clay-like and moderately fertile. The heights above sea level in the region vary between 200 feet and 800 feet to 1,000 feet.
The region has experienced several periods of volcanism. Sedimentary rocks have been intruded by magma from deeper layers of the Earth, forming dikes and platons of granitic rocks. These carry important metals and minerals toward the surface. The Piedmont's bedrock, which is very hard, is made up of granite, gneiss and marble.
One of the most common features of the Piedmont is a distinctive red soil caused by iron found in the rock. The rivers of the region flow from north to south, and streams tend to have shallow beds with narrow banks. This results in the formation of rapids along the waterways.