A cluster of granite monoliths are located near the sources of the Ocmulgee River in Gwinnett & DeKalb Counties. The best known of these are Stone and Panola Mountains. Stone Mountain is 1,683 feet above sea level, and 825 feet above its base. The Lower Piedmont terrain is generally rolling and varies in elevation between 1050 and 550 feet above sea level. Below the Fall Line the elevations along the Ocmulgee River drop gradually from about 500 feet to 250 feet above sea level.
Piedmont of Georgia
The Piedmont of northern Georgia is characterized by hard, crystalline bedrock, either igneous or metamorphic. The terrain is generally rolling hills with some relatively flat terraces and alluvial areas. Most streams flow in fairly straight lines with little or no flood plains. The Piedmont is an ancient land with the faint remnants of some of the oldest mountains on earth. The topsoil is generally thin and now often non-existent due to destructive farming practices in the past.
The sub-soil of the Piedmont is usually red clay, the result of the total degeneration of ancient volcanic rocks. The Coastal Plain was formed from sedimentary rocks during the Cretaceous and Cenozoic Periods. It is generally flat or moderately sloped. Upon entering the Coastal Plain, rivers and streams typically form swamps and then begin to meander. The soil of the Coastal Plain is usually sandy loam with some areas of clay near the Fall Line. Top soils can be quite deep in some locations and very fertile. However, being sandy, it is highly vulnerable to droughts.
Fall Line and Macon Plateau
Ocmulgee National Monument is situated just south of the Fall Line on the Macon Plateau, a boundary between two distinct geological zones, the Piedmont and the Coastal Plain. The peak elevation of this natural terrace is about 50 feet above the Ocmulgee River below and is an extension of the elevations of the Piedmont. The Fall Line appellation arose from the fact that most rivers and streams in Georgia have low falls or shoals near the point where the geology changes.
Most of the Upper Ocmulgee is deep enough to have been easily navigable by Indian canoes, but not steamboats. Nineteenth Century keel boats, and later steamboats, had to unload their cargo and turn around at the Fall Line – creating ideal locations for several of Georgia’s major cities such as Macon, Augusta and Columbus. Until the late 19th century, these towns were inland ports where land, water and rail transportation modes met to serve the commercial needs of the state.
A catastrophic storm struck Georgia around 1200 AD. 1 It caused the Ocmulgee River, just below the Fall Line, to flood at a level never recorded since Georgia was settled in 1733. The river did severe damage to villages along its banks and cut new channels in several locations. The town of Ichesi was located on a horseshoe bend. The new channel of the Ocmulgee cut across the base of the horseshoe, making Ichesi an island. In the centuries since then the river channel has continued to shift westward, but the vestige of the old channel prior to 1200 AD can be seen in the form of an arc-shaped pond, east of the ruins of Ichesi.
Interestingly, the same phenomenon occurred at the same time on the Etowah River in northwest Georgia, 122 miles away from Ichesi. 2 The town of Etula (Etowah Mounds) was also built on a horseshoe bend in a river. The Etowah River flooded the town and cut a new channel across the base of its horseshoe. The pre-1200 AD channel became the moat of a new town about 50 years later.
Georgia’s Coastal Plain
Georgia’s Coastal Plain is a relatively level region, consisting of a progression of sandy terraces that mark ancient shore lines. The region is underlain by relatively young sedimentary rocks, most of which are calciferous. Sinkholes, caused by the decomposition of calciferous rocks immediately under the surface, are common in the portions of the Coastal Plain, closest to Florida.
A band, consisting of thousands of small and medium sized ponds crosses the Upper Coastal Plain immediately south of Ocmulgee Bottoms. These are known as Carolina Bays. 3 In recent years, it has been theorized that these were created by fragments from a comet that broke up in the atmosphere. Some of them may alternatively be ancient sinkholes.
The channel of the Ocmulgee River, south of Ocmulgee Bottoms, does something that looks quite odd on three dimensional terrain maps. It forms an almost perfect arc as it loops to the southeast to join first, the Little Ocmulgee River and then the Oconee River.
Beginning in the late 1500s and continuing through the late 1600s, European maps showed a large lake in central Georgia that received both the Ocmulgee and Oconee River. 4 Its outlet was the Altamaha River, which the French called the May River. The memoirs of the commander of Fort Caroline, René de Laudonnière, wrote in his memoir that several expeditions which he dispatched in a northwestward direction from the fort, encountered a large shallow lake at the headwaters of the May. These expeditions continued northward across the lake in their canoes and then traveled up the Oconee River to the Kingdom of Apalache and then the Appalachian Mountains. No mention is made of the Ocmulgee River by Laudonnière, but it also appeared on later maps of the region, flowing into Lake Tama. Apparently someone, either French or Spanish did canoe northwestward across the shallow lake and travel up the Ocmulgee.
Lake Tama is treated today by most historians as an aberration, but other natural lakes in the lower southeast suggest that it probably once existed. A very similar lake still exists today in South Carolina, Lake Marion. It is located immediately south of the Fall Line and receives the water from two rivers. The Gum Creek Swamp on the Little Ocmulgee River Basin may be the vestige of this former lake. 5
The existence of a Province of Tama on the Lower Ocmulgee River and upper Altamaha River is an established fact. Spanish sources described this province before and after de Laudonnière wrote his memoir. 6 The root word, Tama, is also found in several branches of the historical Creek tribe.
Further reinforcement of De Laudonnière’s description of the lake occurred a hundred years later in a book written by French ethnographer, Charles de Rochefort. 7 In 1658, De Rochefort described the indigenous peoples of French Florida (Georgia) in two chapters of his famous book, l’Histoire Naturelle et Morale des isles Antilles de l’Amérique. He stated that the King of Apalache told a visiting Englishman, Richard Brigstock, that the advanced culture of the Apalache originated on the banks of Lake Tama. Over the centuries that followed their capital gradually moved northward.
De Rochefort’s statement is backed up by archaeology. Both Swift Creek and Napier style pottery originated in the Ocmulgee River Basin, but then moved northward into the Upper Piedmont and Southern Appalachians. 8 The earliest large town in Georgia, now called Ocmulgee, was on the Ocmulgee River. Neither René de Laudonnière nor Charles de Rochefort knew anything about the ruins near present day Macon, GA. They did not make up a “story” to explain the ruins.
The most likely explanation of Lake Tama is that the shallow body of water was created by a log jam that resulted from a cataclysmic storm . . . such as a Class 5 hurricane slamming into Georgia’s Coast Plain. Perhaps the log jam was blown up by early 18th century English traders or it washed away in another storm. It is known that the channels of rivers in Georgia’s Coastal Plain have changed since 1600.
The Tidal Marshes along the coast of Georgia compose a unique ecological zone that is a spawning ground for many fish and water fowl. 9 They move seaward over time when the ocean level is dropping or the land level is rising. As the ocean level is currently rising, they will tend to absorb inland terrain. These marshes are nourished by brine water, which is a mixture of fresh water flowing in from the Coastal Plain and sea water forced landward by the tides and ocean storms. The brine is extremely rich in mineral nutrients and microzoic species such as plankton. In fact, several areas near the outlet of the Altamaha River contain phosphorescent plankton, which make the tidal waterways appear to be filled with electrical sparks at night. The dense populations of fish, shellfish and water fowl in the tidal marshes enabled mankind to create permanent settlements long before they were possible farther inland.
The Barrier Islands off the coast of Georgia are really just enormous sand dunes created by ocean currents and prevailing winds. 10 They are constantly moving, but over time the sand has received enough organic nutrients to support large stands of sub-tropical forests. The soils in the central portions of the larger islands are capable of growing several food crops, if adequately irrigated with fresh water from natural ponds that typify the central areas.
In recent decades the general tendency has been for the islands to erode on the north ends and grow on the south ends. If the level of the Atlantic Ocean continues to rise due to global warming, the islands will undoubtedly also migrate westward along with the marshes. At least during the time of European occupation, Georgia’s islands have received few direct hits from major hurricanes. Hurricanes that strike the Atlantic Coast of Florida tend to go out to sea near Georgia and then cross over the land again from Charleston, SC north to the Outer Banks.
The Ocmulgee-Altamaha River Basin is considered to have a warm-temperate climate. 11 However, the Lower Ocmulgee in Southeast Georgia is usually considered sub-tropical and has a jungle-like appearance. In human comfort terms, this means that there are almost never days in the winter, which are unbearable. Spring and autumn days can vary from being delightful to a little warm. During the winter, it is a very rare year when the temperature drops below 15 degrees. Snow is a very rare occurrence, also.
The region averages 323 frost-free days a year. It also averages 87 days when the temperature rises above 90 F. 11 On 110 days out of the year rain occurs, much of it occurring from January through August. The combination of regular precipitation and a riverine valley creates a average relative humidity of 49% at the Macon Airport. Humidity is much higher in areas adjacent to the river and swamplands. However, the cool spring water near Browns Mount actually cools the air under the tree canopy.
The vegetative cover along the Ocmulgee-Altamaha River today is quite different than what would have existed in Native American times. The Muskogeans selectively cut some tree species to encourage the growth of others, which produced edible nuts or fruits. They planted large orchards of nut and fruit trees. Also, it was a common practice for the Historical Period Creeks to intentionally start fires, which would clear out the underbrush and often create grassy meadows for the deer to graze on.
The majestic Longleaf Pine, in fact, is dependent on brush fires for germination of its seeds and healthy growth. Short-sighted farming practices in the 19th and 20th Centuries drastically reduced the fertility of upland soils – thus favoring scrub species. A European blight wiped out all the American Chestnut trees in the mid-20th century. Throughout the late 20th Century and even today, it is a common practice for timber companies to complete strip land tracts of native tree species and replace them with hybrid pines.
The aboriginal forest in the Piedmont would have been a mixture of numerous hardwoods such as Water Oak, White Oak, Southern Red Oak, American Chestnut, several species of Hickories, Sweetgum, Yellow Poplar and Sassafras, Various scrub pine species would have sprouted in abandoned Indian fields. The now-endemic Loblolly Pine is not native to the Ocmulgee River Basin. Water-loving tree species such as the Sycamore, Butternut, various species of willows, Yellow Birch, Magnolia and Black Gum would have dominated the narrow bottomlands.
The aboriginal forest of the Coastal Plain consisted of extensive stands of massive longleaf pines growing in grassy meadows in the uplands and dense hardwood forests in the bottomlands composed of trees with diameters up to eight feet. There were many evergreen trees and shrubs in the bottomlands such as magnolias, camellias, azaleas, bayberries, etc. These types of aboriginal forests are only visible today along the lower reaches of the Ocmulgee River and the Altamaha River, where timber companies have preserved them. Several species of flowering shrubs and trees that are indigenous to the Ocmulgee-Altamaha Basin are now grown worldwide as ornamentals.
- Thornton, Richard L. (2007) Ancient Roots III: The Indigenous People and Architecture of the Ocmulgee-Altamaha River Basin. Raleigh: Lulu Publishing; p. 120.
- Thornton, Richard L. (2007) Ancient Roots II: The Indigenous People and Architecture of the Etowah River Valley. Raleigh: Lulu Publishing; pp. 56-57.
- Powell, William S. (2004) “Carolina Bays.” Chapel Hill: NCpedia.
- Late 16th and early 17th century French maps label it, “Lake Thama” because the coastal tribes encountered by the explorers from Fort Carolina pronounced it this way.
- Gum Creek is also known as the Little Ocmulgee River.
- Worth, John E. “Spanish Exploration.” New Georgia Encyclopedia. 05 June 2014. Web. 28 December 2014. Hernando de Soto visited Tama in March of 1540. Later Spanish expeditions reached Tama in 1597, 1602 and 1634.
- Charles de Rochefort is considered by European scholars to be the most credible expert on 17th Natural History in the Caribbean Basin. His book was discounted two centuries ago by American academicians because he described an advanced indigenous culture in North Georgia called the Apalache, who built stone architecture.
- Jeffries, Richard W. (1994) “The Swift Creek Site and Woodland Period Platform Mounds in the Southeastern United States.” Ocmulgee Archaeology. Athens: University of Georgia Press; pp. 71-83.
- Seabrook, Charles. “Tidal Marshes.” New Georgia Encyclopedia. 01 April 2014. Web. 28 December 2014.
- Henry, Vernon J. “Geology of the Georgia Coast.” New Georgia Encyclopedia. 18 August 2014. Web. 28 December 2014.
- Hulett, Keith. “Ocmulgee River.” New Georgia Encyclopedia. 20 August 2013. Web. 28 December 2014.