The Holocene sea level changes as evidenced from palaeontological data: A case study from Glauconome sculpta (Bivalvia) along the eastern coast of India

The coastal areas of the world are undergoing severe erosion due to a rapid transgression starting 3000 years ago. The erosion leads to exhumation of an ancient marsh at many places along the eastern coast of India. This marsh supported rich mangrove vegetation and a monospecific bivalve community, Glauconome sculpta (Sowerby), typical of estuarine facies. The bivalves are semi-infaunally positioned in their life mode within the sediments and they apparently monopolized the entire low water belt as opportunists. Present exhumation and exposure of the mud sediments lead to reworking of the bivalve shells and admixing with modern beach fauna. Extensive time-averaging of biota and development of condensed zone are thus in the making. The extermination of the bivalve community and preservation of numerous dead shells in life position point to a rapid rise of sea level that results in quick burial and consequent changes in substrate and salinity. These factors presumably were directly responsible for the evident regional mass mortality of G. sculpta. This palaeontological proxy has been used to understand the post Flandrian transgression during the past 3 ka.