A Note on the Coast and Shelf Evaluation of Sri Lanka in the Late Quaternary

Abstract

The Configuration and the bottom features of the continental shelf of Sri Lanka exhibit characteristics of a drowned extension of the land. Following the post-glacial transgression which began aroud 17,000-18,000 yr B.P. the sea had entered the lower portions of the river valleys forming drowned valleys which roughly extended up to the one hundredfathom isobar (ca.180 m). The ten fathom(ca.20 m)isobar appears to have become a coast line during a later stage. Sea-Level indicatiors such as submerged channels of larger rivers,low-sying ridges and well-marked troughs and terraces found at different levels and drowned forests on the continental shelf confirm that there had been a low stand of sea-level during the last glacial period. It is suggested that the pre-Holocene Red Beds formation, which is widely prevalent on the coastal lowlands of the dry zone, has been deposited by aeolian processes. Therefore, 14C dates pf greologic samples from western and southern coasts of Sri Lanka confirm that the relative sea-level was higher than at present during the mid-Holocene(Main Atlantic)and the Late Holocene (Late Subboreal).