Although there is little historical evidence about what existed in the lands that currently make up the National Heritage Area, by the time of Anglo-American settlement in the early 19th century, the area was sparsely populated by Muscogee and Cherokee Tribes. It is believed that the area was a buffer between the two nations, used as a trade and transportation corridor. The land was ceded to the State of Georgia by the Muscogee in 1821. The land was then distributed to settlers via the Georgia Land Lotteries. Throughout the rest of the 19th and most of the 20th centuries, the area remained very sparsely populated, with many of the roads remaining unpaved until the mid 1900s. The railroad connecting Atlanta and Augusta runs through the area. This railroad helped historically supported Lithonia's quarry industry, which was fed by the granite gneiss of numerous area quarries, including Arabia Mountain. Otherwise, much of the surrounding land was used for small-scale farming. The remains of the agricultural landscape are still visible in the National Heritage Area, including at the Lyon Farm, Vaughters Farm, and Parker House. Small settlements developed along crossroads, the South River, and the railroad, such as the Klondike National Historic District, Flat Rock Community, and downtown Lithonia, Georgia. The existence of the Atlanta Augusta Railroad allowed the granite quarrying industry in the area to flourish in the late 1800s. Remnants of this industry can be seen throughout the Heritage Area in the form of quarry office ruins, rock ledges, and drill holes on the rock. Unlike Arabia, Panola Mountain was never quarried because of its geologic qualities such as softer texture and veining. The proximity of the Arabia Mountain National Heritage Area to Atlanta, the second fastest-growing metropolitan area in the country during the 2000s leaves it vulnerable to overdevelopment. This threat of encroaching sprawl was recognized after nearly a decade, as the area was determined to be a significant part of national history and earned congressional designation as a National Heritage Area in 2006.
Geology
The defining feature that gives the Arabia Mountain National Heritage Area its significance at the national level is its granite outcroppings, called monadnocks. These monadnocks are composed of a granitoid rock and are interspersed with islands of plant life. The Metro-Atlanta area has multiple monadnocks, including Stone Mountain, Arabia Mountain and Panola Mountain. Arabia and Panola Mountains are located within the Heritage Area. The monadnocks were formed when erosion resistant rock is exposed after softer rock is eroded over time. The individual characteristics of the monadnock are determined by the individual processes that formed the granite. For example, Arabia Mountain features a unique "swirl" pattern due to the heat and pressure that caused Arabia Mountain to have a taffy-like consistency when it was cooling over 400 million years ago. Bands of different minerals folded and twisted, creating the "tidal swirl" pattern seen today. By contrast, Panola Mountain has a flakier rock with less compressive strength due to differences in cooling rates. Panola Mountain also has a darker colored rock and different mineral grains. Differences in mineral composition between Panola and Stone Mountains indicated different magma sources at the time of formation.
Natural Systems
Primary Succession: It took thousands of years for plants and trees to grow in the granite outcroppings. The first plants on the mountains were lichens, which draw nutrients from dust and rainwater. Acids from these lichens and mosses gradually formed pits in the rock, called chemical erosion. This allowed shallow amounts of soil to accumulate, providing a place for more plant life to take root. This process is called Primary Succession as a succession of plants colonize the rock from lichen, to mosses, to diamorpha and larger plants, then gradually accumulating enough soil to support shrubs and trees. Physical Weathering: Not only does plant matter such as moss erode the rock and help to build soil levels in the pits, but the stone is also weathered by non-chemical factors. Wind, freeze-thaw cycles, and even lightning strikes cause the rock to fragment and breakdown. Cracks can form, giving another foothold to plant life, and the rock is broken into particles that add to the shallow soil. The Edge Effect: Due to the variety of eco-systems within the Heritage Area, the "edge effect" allows for greater biodiversity where two or more ecosystems intersect. For example, where the rock outcroppings border forests, the shallow soil retains more moisture due to runoff and can support the species of both the rock outcropping and the forest.
