Formation of Western Ghats

It has long been considered that the Western Ghats are the result of a long fault parallel to the coast extending from the gulf of Cambay to Cape Comorin .This hypothesis is supported by several observations and reasionongs such as existence of hot springs parallel to the sea between North Bombay and Ratnagiri.

Later works and off-shore petroleum researches lead to the conception of an entirely different mechanism for the formation of western Ghats. Taking recent studies on the palaeocontinent into account, we can propose a scheme for the formation of the western Ghats, starting with the break of Gondwana. How and when the drift of the Indian continent took place varies with different authors .According to Craddock (1977), separation of the Indo-Antarctic continent from Africa began in the late Triassic and continued throughout the Jurassic and the drift proper started during late Jurassic ; the separation of India and Antarctica took place during the Cretaceous period Vilas and Valencio (1977) felt that palaeomagnetism indicated that Africa, Madagascar and India were still together during late Cretaceous-Early Tertiary period .Smith et al (1981) believe the separation of the Madagascar -India Ceylon block from Africa and Antarctica to have taken place between late Jurassic and Early Cretaceous .As early as the Paleocene, North India approached the equator which the Mysore region had traversed during the Eocene .India took present position during the Miocene.

It is probable that the basaltic outpourings of the deccan are the result of gigantic and repeated faults accompanying the Indian drift because the two phenomena as contemporary events .These out pouring extended well beyond the present coast as attested by offshore drillings as during Eocene, certain parts off Bombay were still above the sea level.The entire region was subjected to a number of faults resulting in the Grabens mentioned earlier, but none of them seem to be a directly responsible for the formation of the Ghats.

The western part of the peninsular was elevated during the Tertiary in successive phases .the movements of uplift triggered off several small and medium faults.It is [probably one of these that responsible for the incline of the Trap towards the west near the Bombay and for the hot springs mentioned above.The erection of the Nilgiri host probably dates back to Late Tertiary Early Quaternary period and is the result of isotonic adjustments It is likely that this revival tectonic activity in the Deccan corresponds to the consequences of the meeting of the Indian plate with that of Eurasia which is also responsible for the formation of the Himalayas in the Miocene.

The uplift of the western part of the continent had several repercussions it explains the orientation of the big rivers of the plateau towards the east ;it started a chain of very violent regressive erosion on the steep and abrupt western slopes, thus fashioning the Western Ghats into the state that we find them in today:chiselled into steps following the basaltic beds (in the Trap) and carved by deep valleys sometimes capturing some of the rivers of the plateau such as Sharavathi or cleaved by vertical cliffs as found towards Agumbe.The seaward progression of the edge of the continental plateau as compared to the ancient continental edge is perhaps the outcome of this erosion.