National Park Service Ocmulgee Mounds U.S. Department of Interior Ocmulgee Mounds NHP

Archaeology: Our Window to the Past

LARGEST DIG Did you know that the largest dig ever a timeline of people who lived on the IN THE USA conducted in this country occurred Macon Plateau between 12,000 BCE and here at Ocmulgee and the surrounding 1800 CE. Each of the major periods was area? Between 1933 and 1936, over represented here at Ocmulgee: Paleo 800 men in Roosevelt’s Works Progress (15,000-8,000 BCE), Archaic (8,000-1,000 Administration (WPA), Civil Works BCE), Woodland (1,000 BCE-900 CE), Administration (CWA), Federal Emergency Mississippian (the mound builders at Relief Administration (ERA & FERA) Ocmulgee, 900-1540 CE), and Historic and later the Civilian Conservation Corps (when written records were kept, (CCC) excavated under the direction of 1540-present). Dr. Arthur R. Kelly from the Smithsonian Institute. Kelly was the only archaeologist at the Ocmulgee camp and conducted evening training courses for the men. Hundreds of thousands of artifacts were discovered including pottery, pottery sherds, metals, arrowheads, spear points, stone tools, pipes, bells, jewelry, seeds, bones, etc. – some of which is on display in the Ocmulgee Mounds National Historical Park museum or stored in the museum curatorial. This dig helped piece together (ARCHAEOLOGISTS UNCOVERING THE EARTH LODGE)

DATING Relative Dating techniques can be used to changes can also be used for relative dating METHODS find out if one culture is older or younger of archaeological material. Biological than another, but these techniques do criteria can also be used for relative not give a specific year. The famous dating. Fossils, palynology (microscopic Kelly excavations conducted here at examination of fossil pollen grains in Ocmulgee used a relative dating technique stratified peat or lake deposits to determine called stratigraphy. In stratigraphy, an plants), and floral time charts are all archaeologist observes the soil stratum biological criteria helpful in relative dating. (layer) where artifacts are found. Deeper stratums mean older artifacts, rocks, or Absolute Dating means that the technique fossils. Seriation is a technique involving used can give an age in years. Physicists the description of stylistic changes in use radiocarbon dating to measure the artifacts as well as their popularity. amount of radioactive carbon (C14) in Another way of determining relative age is pieces of organic material such as bone, typology. People of the same culture will wood, or shell found at archeological almost always make their tools, decorate sites. When something dies, it begins to their pottery, or build their houses in lose radioactive carbon. The smaller the similar ways. For instance, when projectile amount found, the older the artifact. The points (spear points and arrowheads) are physicist can give the archaeologist a date found to be made in the same shape (or (plus or minus 200 years) for the artifact type), it is safe to say people of similar tested. One helpful tool for physicists is cultures made them. Technological the accelerator mass spectrometer, which DATING counts carbon in small samples and allows racemization (measuring amino- METHODS artifacts to be dated more accurately than acid chemical changes that occur over (CONTINUED) the conventional radiocarbon method used time) and obsidian hydration (used before the 1980s. where obsidian is abundant such as Mesoamerica). Paleomagnetic Dating is For those interested in technical based on changes in the orientation and descriptions, there are other absolute intensity of the earth’s magnetic field that dating techniques. Radioactive Dating have occurred over time. The magnetic methods are the most widely used and characteristics of an object or area are accepted absolute dating methods. They matched to a date range when the earth’s are based on the natural radioactivity of magnetism was similar. Scientists can also certain minerals found in rocks. The rate date igneous and sedimentary rocks, which of radioactive decay of particular isotopes are rich in magnet particles based on a is known so the age of a specimen can be record of the earth’s polarity. Fluorine computed from the remaining radioactive Dating is useful for dating early human material and its decay products (example: remains. Buried bones absorb fluorine uranium -238 to lead -206 or potassium -40 from surrounding soils. The amount of to argon -40). Each radioactive member in fluorine is proportional to the amount in these series has a known, constant decay the surrounding deposit and the time that rate and age range, which allows excavated the bone was buried. This method may not rocks to be dated. Other somewhat be considered absolute, but can be used unreliable radioactive dating methods to measure the ages of bones found at the include fission track (when uranium -238 same site. atoms fission within a solid medium such as a mineral or a glass, they expel charged particles that leave a trail of damage called fission tracks which are a function of time), thermoluminescence (based on the luminescence produced when a solid is heated – used in dating pottery), and electron-spin resonance (measuring the amount of trapped electrons by detecting the amount of microwave radiation they absorb). Although the last three techniques are somewhat unreliable, museums often use them to determine if a ceramic piece is an antique or a forgery.

(AN ARCHAEOLOGIST AT A DIG SITE) Chemical Dating includes amino-acid

OUR ROLE In 1933, concerned Macon citizens otherwise alter or deface or attempt to recruited Dr. Arthur Kelly from the excavate, remove, damage, or otherwise Smithsonian in order to understand the alter or deface any archaeological importance and history of Ocmulgee. resources located on public lands or Indian What would have become of the area lands unless such activity is pursuant to a if they had not? It is important that permit . . . or the exemption for Indians on everyone understand the urgent need for their own tribal lands . . . no person may preserving the archeological resources in sell, purchase, exchange, transport, receive, Georgia. It is everyone’s responsibility. or offer to do the same if such resource was If construction or vandalism destroys excavated or removed from public lands or a site, the window is broken and the Indian lands.” archeological information is lost forever leaving little chance for you to find Georgia Law: GCA § 40-813a states history on your next walk. You can learn that “The State of Georgia . . . reserves more about the mysteries of archaeology to itself the exclusive right and privilege by visiting a museum, participating in of exploring, excavating, or surveying archeological digs, attending a lecture, or all prehistoric and historic sites, ruins, visiting archeological web sites. The more artifacts, treasure, treasure-trove, and we study the past, the more we learn about other similar sites and objects found on all ourselves. lands owned or controlled by the state.”

Federal Law: Archaeological Resources Protection Act of 1979 states “No person may excavate, remove, damage, or

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