1847.] CLARK ON THE NEIGHBOURHOOD OF BOMBAY. 223 



It would be tedious to enumerate the evidences, but the history of 

 the matter seems to be as follows : — The original peninsula was me- 

 tamorphic, raised and supported by granites of various ages, and 

 covered up partially by the diamond sandstones and argillaceous lime- 

 stones, the whole being traversed by greenstone dykes. 



Next, the whole mass being still below the sea, a line of volcanic vents 

 seems to have burst forth along the western coast ; all the eastern 

 ejections from these rolled, at a very moderate dip, over the older rocks, 

 while the western ejections descended at once into the deep sea. 



As the accumulation proceeded the volcanic region gained eleva- 

 tion, and finally reached a height of at least 5000 feet above the pre- 

 sent sea-level, or perhaps it would be more correct to say above the 

 beds now forming the sea-shore. The later eruptive period produced 

 basalt, beds of which mantle the western coast and cap the Ghauts. 

 This basalt seems to have flowed out rather in long coulees than in 

 sheets, and to have formed the mountain ridges which run eastwards 

 from the crest of the Ghauts. 



After this came a period of basaltic dykes. These seem to have 

 closed the scene, for they traverse the craters as well as the adjacent 

 rocks, and though confined for the most part to the crater region, 

 they lie along and parallel to it, and seem to have been injected, not 

 from the individual craters, but from some deeper-seated action aifect- 

 ing the whole. 



Many of these dykes are above fifty feet thick, are highly colum- 

 nar, and extend for many miles ; they are seldom found east of the 

 Ghauts, but they cleave the highest mountains upon them. 



Denuding forces seem next to have come into action. The whole 

 surface of the Deccan presents evidences of the action, I think the 

 gradual action, of water. The rocks being undisturbed the water 

 cut its way slowly, but it* did cut its way, cutting through rather 

 than lifting up the beds. All the Deccan valleys are valleys of exca- 

 vation, and I have seen no trace of any thing Hke an extensive fault ; 

 in fact I do not think I have seen a fault at all. 



In the volcanic region the case is wholly different. The water was 

 admitted, through the craters and the dykes, which are fissured and 

 everywhere loose, at once into the interior of the mass, and the result 

 has been the removal, with some exceptions (which remain as evi- 

 dences), of the whole of the upper 5000 or 6000 feet of volcanic 

 matter. The waters have not cut the rocks as in the Deccan, but 

 have dissected them out neatly; and the valleys, except near the sea, 

 are not water-worn, but are evidently formed by the meeting of lava 

 streams, often actually meeting at a sharp angle, and sometimes such 

 valleys are partially filled up by a third stream. The rocks are com- 

 monly hard, and the water-flow has often been unable even to efface 

 the sort of ripple-mark that is so common in lava streams. 



I believe the distinction between the Konkun and the Deccan (and 

 therefore the Ghauts) to be due entirely to the loose structure of the 

 former and the dense undisturbed structure of the latter, and, in the 

 absence of anything like a great line of fault, it is difficult to 

 account for the Ghauts in any other manner. The Konkun is in fact 



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