An Encyclopaedia of Indian Archaeology v1.c14.s11: 9.11 Sea Level
An Encyclopaedia of Indian Archaeology v1.c14.s11
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9.11 Sea Level
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The relative level of land and sea has been changing with time. The land either rises or sinks with respect to the sea level because of tectonic or isotatic causes. The sea level changes both because of the changes in the size of the sea basin or the volume of water in it. During the Glacial periods a lot of water was locked in the glaciers, as a result of which the sea level went down by as much as 100 m; conversely, the sea level came up during the Interglacial periods. Such sea-land relationship changes affected human habitations also. Recent work (Agrawal, *et al.*, 1973; Agrawal and Kusumgar, 1974; Gupta, 1972) on the w. coast of India shows that before 30000 to 35000 B.P. the sea level was several m lower than today. Around 30000 B.P. the sea level reached a level a few m higher than the present. There was a regression soon after. Around 15000 B.P. the sea started rising again reaching a height of c. 3 m above the present level around 5000 B.P. These changes naturally affected early man. When the sea level went down by 100 m most of the continental shelf would have become available for occupation. The vegetation belts would also have moved down or up in response to the changes. The evidence of submerged forests around Bangalore and Bombay supports such a hypothesis.
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It is reported that the remains of some historical coastal towns of the s. are submerged now. In the Bombay area during +3 m transgression around 5000 B.P. the microlithic man occupied only the island promontories [4.5; KANDIVLI]. No microlithic sites can be traced at the situations that are near the present sea levels. Obviously communication and fishing must have been carried on with the help of canoes only.
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If the LOTHAL hypothesis is to be accepted, the site could be approachable only during +3 to +5 m sea level rise as suggested by Gupta, 1972.
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An indirect use of the sea level changes is to date Stone Age artefacts. The coastal rivers of Maharashtra like the Vaitarna, Ulhas, etc., show three cycles of erosion and aggradation. Marine transgressions should result in aggradation and regressions in erosion. Since the sea level curve is now dated, one can indirectly date the implimentiferous sediments of these rivers. The middle gravels of the Vaitarna, for example, contain Middle Palaeolithic tools [4.3.] which could thus be dated to a transgression around 30000 B.P.
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In Saurashtra the miliolite rocks [9.7; 9.8.2] were formed during marine incursions. During regressions they were exposed, deflated and transported inland by wind. It is interesting to note that Middle Palaeolithic tools have been found in inset terraces cut into miliolite, thus showing that they are younger than the miliolites. Gupta, 1972, has dated one of the transgressions in this area round 30000 B.P. Oyster shell beds from the Hiran bed and Badalpur give 25000±5000 B.P. dates. On the other hand a site near Junagadh yielded Acheulian tools from below the aeolian miliolites. By extrapolation we can thus date the Middle Palaeolithic tools to less than 30000 years B.P. and the Acheulian ones to more than 30000 years B.P.
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Agrawal, D.P., Avasia, R.K., & Guzder, S.K., 1973, in Agrawal, D.P., & Ghosh, A., ed., *Radiocarbon & Indian Arch.*, Bombay (for multidisciplinary approach to Quaternary problems). Agrawal, D.P., & Kusumgar, S., 1974, *Prehistoric Chronology & Radiocarbon Dating in India*, New Delhi. Ahmad, E., 1972, *Coastal Geomorphology of India*, New Delhi. Gupta, S.P., 1972, in *Jour. Geology*, 80, pp. 357-61.—D.P. AGRAWAL