The Indian Ocean earthquake of 26 December 2004 led to significant ground deformation in the Andaman and Nicobar region, accounting for ϳ800 km of the rupture. Part of this article deals with coseismic changes along these islands, observable from coastal morphology, biological indicators, and Global Positioning System (GPS) data. Our studies indicate that the islands south of 10Њ N latitude coseismically subsided by 1-1.5 m, both on their eastern and western margins, whereas those to the north showed a mixed response. The western margin of the Middle Andaman emerged by Ͼ1 m, and the eastern margin submerged by the same amount. In the North Andaman, both western and eastern margins emerged by Ͼ1 m. We also assess the pattern of long-term deformation (uplift/subsidence) and attempt to reconstruct earthquake/tsunami history, with the available data. Geological evidence for past submergence includes dead mangrove vegetation dating to 740 ‫ע‬ 100 yr B.P., near Port Blair and peat layers at 2-4 m and 10-15 m depths observed in core samples from nearby locations. Preliminary paleoseismological/tsunami evidence from the Andaman and Nicobar region and from the east coast of India, suggest at least one predecessor for the 2004 earthquake 900-1000 years ago. The history of earthquakes, although incomplete at this stage, seems to imply that the 2004-type earthquakes are infrequent and follow variable intervals.

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Results of petrographic, mineralogic and granulometric studies of the sedimentary china clay deposits of Trivandrum district in south Kerala are discussed in terms of their origin and depositional environment. While mineratogie data indicate a khondafitic source for the kaolins as against the hitherto postulated leptynitic source, petrographic evidences suggest that most of the kaolinite were transported from the weathering crust and deposited. Granulometric data and SEM scanning of sand grains from the clays indicate their deposition in a fluvial/low energy littoral environment under conditions of subaqueous agitation.