Radiocarbon Ages of Beach Rock and Quaternary Sea Level Changes in the Southern Part of the Vaigai Pro-Delta, South India

The Vaigai River delta has unique geomorphic landforms along the east coast, including many sets of beach ridges/swales, emerged beach rock, marine notch structures, etc. These landforms have been used to reconstruct the Palaeo sea level curve and demonstrate the evolution of the coast during the late Quaternary period. In this work, for the first time, we endeavoured to perform the absolute radiocarbon ages of shell substances collected from the beach rock present beneath the inland beach ridge systems. The 14C ages of the beach rock along the prodelta part of the Vaigai River showed that the beach rock beds ranged between 39, 000 and 6000 BP in this region. The results of this study specify the beach rock formations that occurred at +6 m belong to the late Pleistocene period and correspond to Marine Isotope Stage 3 (MIS-3). In the Valinokkam coastal region, the beach rock superimposed on teri/red sediments yielded an age of 21038 BP. As a result, the teri/red sediments in this study area are significantly older than the beach rock and deposited in the last glaciation period (MIS-2) up to +4 m above the present mean sea level. However, the Mid Holocene (MIS-1) sea level rose +2 m above the present sea level and was followed by a relative sea level fall along the coastline of the Vaigai delta. A steady rate of upliftment along the coastal regions of the Vaigai delta can be inferred from the discrepancy between 14C ages and elevations of the beach ridges and beach rock.