Evolutionof Coastallaridformsinthe Western Part of Srilanka
HiroshimaHiroshimaGeographicalAssociation Geographical Association Geographical Sciences vol, 43 no.1 pp, 18-36, 1988 Evolution of Coastal Laridforms inthe Western Part of Sri Lanka JINADASA KATUPOTHA* Key Words:evolution of coastal landforms, SriLanka, late Pleistocene, Holocene, landfOmi classMcation Abstract Geomorphic and geologic evidence shows four different stages {Stage I-IV} in the evolution of coastal landforrns on the west coast of Sri Lanka during the Iate Pleistocene and Holocene Epochs. The author assumes that the old ridges in Stage I at Sembulailarna, Kiriyanl(ailiya, Pambala, Wiraliena, Uluambalarna and Kadrana areas have been fonned precedng the Holocene transgression. Low hMs and ridges in the area were coated mainly by wind blown sand, fonowing the lower sea levels during the Late Pleistocene and Earty Holocene Epochs. Radiocarbon datings en the west and seuth coast$ reveal that the sea level remained 1rn or more above the present sea level between 6170± 70 and 535e± 80 yr B. P. During this transgression, the forTner drainage basins were submerged and headland bay beaches were ereated. Many wetlands aiid beach ridges, particularly in Stages ll, III, and IV were gradualy formed owing to rninor oscMations of sea levet after mid-Holocene. Most of these landiorTns haveaclose relationship with main climatic zenes of the country. 1987; Katupotha, 1988) also help to deterrnine their I. Introduction evolution. The island of Sri Lanka has a coastline over Coastal Iandform maps of the study area were 1920 km in length, exhibiting a diversity of coastal cornpiled by means of interpretation of aerial photo- landromis. The coastal lowlands with elevation graphs (1:40,OOO-Survey Department of Sri Lanka, from mean sea level (MSL) to 30m consist of 1956) and field observations.
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