Palaeomangroves of Kanara coast, Karnataka, India and their implications on Late Pleistocene sea-level changes

Abstract

Along the Kanara coast, some wells, show an organic clay layer, 1.5 to 7 m thick, between a layer of 2 to 6 m of coarse yellow sand above and white sand and pebbles below. The altitude of this intermediate organic clay formation is more or less at the present mean sea-level. Palynological analyses reveal that this sediment had been deposited within a mangrove environment i.e. at sea-level, while the 14 C datings give ages older than 40,000 years B. P. No proof of vertical movements after the deposit of the intermediate organic clay formation has been put forward up to now. Therefore, it can be accepted that the present elevation of this formation is more or less the same as its original altitude i.e., the present sea-level. Comparison of this altitude with the curves of global sea-level changes indicates that the period of deposition of these organic sediments should be around 125,000 years B.P., during the last Interglacial (Eemian) when the sea-level was ± the same that it is today. The main characteristics of “Eemian” flora were the same as the present. The climatic regime may have been slightly different with the less contrasting season.