Atlanta metropolitan area

Geography

The area sprawls across the low foothills of the Appalachian Mountains to the north and the Piedmont to the south. The northern and some western suburbs tend to be higher and significantly more hilly than the southern and eastern suburbs. The average elevation is around 1,000 feet (300 m).

The highest point in the immediate area is Kennesaw Mountain at 1,808 ft (551 m), followed by Stone Mountain at 1,686 ft (514 m), Sweat Mountain at 1,640 ft (500 m), and Little Kennesaw Mountain at 1,600 ft (488 m). Others include Blackjack Mountain, Lost Mountain, Brushy Mountain, Pine Mountain, and Mount Wilkinson (Vinings Mountain). Many of these play prominently in the various battles of the Atlanta Campaign during the American Civil War. If the further-north counties are included, Bear Mountain is highest, followed by Pine Log Mountain, Sawnee Mountain, and Hanging Mountain, followed by the others listed above. Stone, Sweat, Bear, and Sawnee are all home to some of the areas broadcast stations.

The areas subsoil is a dense clay soil, colored rusty by the iron oxide present in it. It becomes very muddy and sticky when wet, and hard when dry, and stains light-colored carpets and clothing easily. It also tends to have a low pH, further aggravating gardeners. The fineness of it also means it is easily deposited into streams during heavy rains, creating silt problems where it is exposed due to construction. This transported red soil can be seen downstream on the riverbanks of south Georgia (where the native clay is white), and down to the Florida panhandle (where the native sand is also white). Topsoil is present only in natural forest areas, created by the decomposition of leaf litter.

An extinct fault line called the Brevard Fault runs roughly parallel to the Chattahoochee River, but as its last movements were apparently prehistoric, it is considered extinct and not a threat to the region. Still, minor earthquakes do rattle the area (and all of Georgia) occasionally. One notable one was in April 2003 (magnitude 4.6) coming from the northwest, its epicenter just across the state line in northeastern Alabama. While many people slept through the 5A.M. quake, it caused a minor panic in others completely unaware of what was happening. Similar earthquakes occur in this region called the Eastern Tennessee Seismic Zone, often felt much more widely across the stronger crust of eastern North America as compared to the west. Thus, the 1886 Charleston, South Carolina earthquake was also felt in Atlanta and throughout the Southeast. It caused damage as far as central Alabama and West Virginia. Two small earthquakes were also felt on the southeast side near Eatonton in early April 2009. The New Madrid Seismic Zone (near the Missouri-Tennessee borders) and the seismic zone producing the 1886 magnitude 7.3 earthquake are still capable of producing moderate or major earthquakes, in which the entire Atlanta area will feel moderately or even strongly.