In a major turning point in the cultural historiography of the ancient Sangam Age, the Tamil Nadu Archaeology Department (TNAD) has stated that the cultural deposits unearthed during excavations at Keeladi in Sivaganga district in TAMIL Nadu could be traced between 6th century BCE and the 1st century CE (600 BC-100AD) More about the site
- Sangam age is generally considered between 300BC and 300 AD.
- But the Sangam age materials unearthed from Keeladi site and sent for carbon dating test in the U.S. dates back to 580 BCE.
- Six carbon samples collected from the fourth season of excavations at Keeladi were sent to Beta Analytic Lab, Miami, Florida, U.S., for Accelerator Mass Spectrometry (AMS) dating.
- The report titled, ‘Keeladi-An Urban Settlement of Sangam Age on the Banks of River Vaigai’, was published by the
- The results from the fourth excavations suggest that the second urbanization [the first being Indus] of Vaigai plains happened in Tamil Nadu around 6th century BCE as it happened in Gangetic plains.
- The report also corrects the site name as Keeladi as against the previously used
- Tamil - Brahmi older - The recent scientific dates obtained for Keeladi findings push back the date of Tamil-Brahmi script to another century, i.e., 6th century BCE.
Accelerator Mass Spectrometry (AMS)
- These results confirmed that literacy and the art of writing had been attained as early as the 6th century BCE.
- The finding also suggests that the society in Keeladi had used animals predominantly for agricultural purposes.
- Pottery specimens from Keeladi sent to the Earth Science Department of Pisa University, Italy, through Vellore Institute of Technology for mineral analysis, confirmed that water containers and cooking vessels were shaped out of locally available raw materials.
- While three excavations were undertaken by the Archaeological Survey of India, the fourth excavation was undertaken by the TNAD.
- The fifth excavation by the TNAD is underway.
- AMS dating involves accelerating the ions to extraordinarily high kinetic energies followed by mass analysis.
- Although more expensive than radiometric dating, AMS dating has higher precision and needs small sample sizes.
- There are two techniques in measuring radiocarbon in samples
- Radiometric dating
- Accelerator Mass Spectrometry (AMS).
Difference between both processes?
- The two techniques are used primarily in determining carbon 14 content of archaeological artifacts and geological samples.
Advantages of AMS:
- Radiometric dating methods detect beta particles from the decay of carbon 14 atoms
- On the other hand, accelerator mass spectrometers count the number of carbon 14 atoms present in the sample.
Also read: Road Accidents kill 400/day, 1/4th Of Them In UP & Tamil Nadu Source 1 Source 2
- The greatest advantage that AMS radiocarbon dating has over radiometric methods is small sample size.
- Radiocarbon dating is a destructive process. Hence, because of its ability to analyze samples even in minute amounts, accelerator mass spectrometry is the method of choice for archaeologists with small artifacts and those who cannot destroy very expensive or rare materials.
- Due to the sensitivity of accelerator mass spectrometers, carbon dating small particles like blood particles, a grain, or a seed has been made possible.
- Accelerator mass spectrometry also takes less time to analyze samples for carbon 14 content compared to radiometric dating methods that can take one or two days. An accelerator mass spectrometer has a run time of a few hours per sample.
- Lastly, it must be noted that AMS measurements usually achieve higher precision and lower backgrounds than radiometric dating methods.