138 JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, 1890 



island at which way-farers, after fording the last creek, washed 

 the mud from their feet before entering- the town. 



This single island of ours then, only two hundred years ago, was 

 a group of at least seven distinct islets, and in the ages before 

 that, ere the work of silting up had progressed so far as it had then, 

 must have been an archipelago of what for the most part were little 

 more than mere island rocks. 



But the book we are reading carries their history yet further back. 

 You remember I spoke just now of a dip in the strata at the 

 quarry below Cumballa Hill. Now the same dip you will find, no1 

 only in the other ridge on the eastern side of this island, but in 

 Salsette, into which we traced this very rock of Cumballa Hill on 

 which we stand. Not only so, but it is observable in the other islands 

 of the harbour, which together make up the Bombay group. These, 

 with Bombay, would seem then once to have formed one continuous 

 whole. 



But the book does not stop there. If you cross the harbour, you 

 will find this same dip on the main land, extending from some hills 

 near Panwel, about 9 miles inland, to the sea, and running longi- 

 tudinally up and down the coast, a distance of some 130 miles, from 

 some way south of Bombay to near Daroaun in the north. It is 

 especially noticeable here, because, with the exception of this small 

 area, the stratification of the neighbouring rocks is for many miles 

 remarkably level, though they are all of precisely the same forma- 

 tion as those that partake in the dip. 



Originally, then, it would seem, this island of ours was not an 

 island at all, but a portion of the main-land, and when broken off 

 from that it became a cluster of small rocky islets. 



What, then, was the force that broke this fragment from the main- 

 land ? Probably the same that produced the dip. That evidently 

 might be caused either by an elevation at the eastern end, or a 

 depression at the western. In the former case, there would probably 

 be some dislocation of the strata about the line of up-heaval. But 

 there is none visible, h therefore seems probable that the dip was 

 caused by a subsidence in the west. But the general subsidence 

 of a line of country near the coasl would, of course, let in the sea 

 over the lower portions and round the higher, so as to make islands 



