Abstract:
Undisturbed sediment compiles are invaluable samples in the reconstruction of ancient
depositional environments. Basically coastal sedimentation is significant as it preserves
the eustatic and isostatic records as well as seasonal climate records. Present study
concerns on sedimentology of recent sediments of a part of the eastern coastal lagoon
area of Sri Lanka to interpret the depositional history. Spatial extent of sediments was
studied by field mapping. Gradation analysis and morphology of sediments were used
to identify the depositional history of sediments. The results revealed that the spatial
extent of the recent sediment deposition is about 4km wide band from the present coast
line including the lagoon environment that overlaid the weathered residual soil. Top
sediments (up to 1m) are characterized by different layers with several depositional
histories and did not indicate any remarkable clayey layer even though the locations are
near to a river input and within the flood level. It can be said the inorganic input is
prominent than the organic input in the eastern coastal sedimentation. The results need
to be proved by other geochemical and age dating proxies.
