Luminescence dating of late holocene dunes showing remnants of early settlement in Cuddalore and evidence of monsoon activity in south east India

In this study dunes from south east India were dated using optically stimulated luminescence (OSL) to reconstruct the depositional history. A belt of dunes has developed parallel to the coast between Pondicherry and Karikal in Tamil Nadu, south east India. In the area between Cuddalore and Porto Novo the dune belt is 5. km wide. A transect from the coast to the most western dune inland was investigated. Changes in the environmental conditions are recorded in the dunes. They show features including unconformities, changes in the direction of bedding, erosional features, water escape structures and remnants of human settlements. The OSL results show that strong changes in the environmental conditions occurred about 100 and 300 years ago. The latter event marks also the termination of settlement in this place. The settlement period started about 1500 years previously. The periods of sand mobility and stabilisation of the land surface by soil formation correlate with changes in the precipitation record of India. The investigated dunes very likely reflect fluctuations in the monsoon activity during the last 3500 years in south east India.