Delineation of sub-bottom geomorphic features in the inner Gulf of Kachchh, western India, reveals superimposition of two contrasting environments of deposition. The strong tidal currents are presently eroding creeks, modifying the horizontally deposited sediments into uneven to rugged physiography. The inner gulf, before its division into the creeks, is, however, experiencing deposition of the sediments released as a result of the denudation of the creeks, over an erosional surface, which is now buried under about 18 m thick sediments. Thus, the present prevalent trend in the environment of deposition appears to have been reversed. The factors influencing this reversal are (1) marine transgression in the gulf since the Pleistocene; (2) subsidence of the gulf at around 13,000 bp, associated with seismic activity, both of these factors increase the area under the influence of erosional processes; (3) widening and extension of the gulf due to erosion along the zones of tectonic weakness, resulting in the modification of physiography and (4) many-fold amplification of the tidal range. A three-stage model is suggested for the present physiographic setting of the Gulf of Kachchh. © 1990.
