Journal of Geological Society of India (Online archive from Vol 1 to Vol 78)

R. Vaidyanadhan ¹, K. L. V. Ramana Rao ¹, Y. J. Pardhasaradhi ¹

Affiliations
1 Department of Geology, Andhra University, Wahair, IN

Abstract

No Abstract.

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Y. J. Pardhasaradhi ¹, R. Vaidyanadhan ²

Affiliations
1 Department of Geology, Andhra University, Waltair, IN
2 Department of Geography, Andhra University, Waltair, IN

Abstract

Two relict levels of erosion over the Nilgiri are recognised within a polycyclic and polygenetic planar Nilgiri surface. Landform study suggests a pediment cycle for the Ootacamund landforms, the younger of the two relict landforms. The older Dodabetta landforms now stand as vestiges of the original ground at higher elevations. Climate might have been less humid over a major part of this region during the period of pedimentation (post-Miocene) compared to earlier and later times. The Quaternary lowering of temperature in Pleistocene and subsequent warming up of climate are likely to have resulted in the formation of swampy courses, alluvial tracts and peaty subsoils along certain streams over the Nilgiri.

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Y. J. Pardhasaradhi ¹

Affiliations
1 Calcutta, IN

Abstract

Soon after the foundering of the western block there was a period of intense planation of the west coast acting landward. This was followed by deposition of marginal deposits of Miocene and a relative uplift of the entire western segment raising the Kerala plains to more or less their present position. Geomorphic processes toward the development of a planar surface continued. A tentative scarp limit is drawn roughly parallel to the west coast which limits the uniformly developed high level landforms and the erosion outliers on the east and the estuarine courses to its west. Features observed suggest this landscape of Malabar uplands to have developed as an etchplain. A main period of lateritisation of this surface must have been initiated in late Tertiary-early Cainozoic times. Towards the closing period of the main lateritisation and soon after, the planar surface was monoclinally warped roughly parallel and close to the west coast. This warped surface has contributed sediments to shelf deposits during recent times. This surface can be traced at certain places to form sea stacks and even surviving under the shelf deposits close to the coast. The etchplain development of the Malabar uplands could be extended to the rest of the lateritised landscape of the west coast.

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