Some observations on the recession of the Western Ghat escarpment in the Deccan Trap region, India: based on geomorphological evidence

Abstract

In the western Indian Peninsula, a huge escarpment, the Western Ghat, stands high and wall-like. Whether this mega-geomorphic feature is the result of prolonged erosional and recessional processes following rifting and cessation of the Deccan Trap activity in the late Cretaceous (ca. 65 Ma) or the product of erosion and retreat of a fault scarp created in the vicinity of the present-day scarpline or the coastline, has been the subject of considerable discussion. To investigate this, we have used the Ghat crestline planform, the beheaded valley lengths, the offshoot lengths and the present distribution of coastal laterites in the Deccan Trap Region. Our interpretation is that the Western Ghat escarpment has receded maximum by a few tens of kilometers only by fluvial erosion. This is not consistent with the existing and largely accepted model that envisages parallel slope retreat by 120-180 km of the continental edge created by rifting in the late Cretaceous. Recent studies of many passive margin great escarpments in other continents provide support to our observations.