THE GEOLOGY 01 WORLl HILL. 583 



to the second period. Though Dr. Carter was the first of the earlier investi- 

 gators to give a very painstaking, careful and elaborate description of the 

 various geological formations of Bombay his assumptions about the sequence 

 of the several volcanic effusions and their sub-divisions into four groups seem 

 to be open to question, as Wynne remarks in deaUng with the geology of 

 Bombay in the Memoirs of the Geo. Survey of India, Vol. V, 1863. Were it a 

 fact that this upper trap overflowed " the then plain of Bombay " and was 

 subsequently forced up together with the sedimentary beds on which it was 

 lying, by a fresh outbreak of lava underneath to form the existing ridge the 

 aqueous deposits would have shown a more extensive disturbance by way of 

 contortion, fracture and fusion than is actually the case. The upper trap itself 

 wovdd have tmdergone a good deal of Assuring beyond the very thin joints due 

 to cooHng. At Sewri the upper trap takes the contour of the lower trap and 

 that of the thin layer of sedimentary rock and has the air tubes perfectly 

 vertical and undisturbed. The probability is that the ridge was already formed 

 by the forcing up of the aqueous stratum by the irruption underneath of the 

 lower trap before the upper basaltic trap came on. 



Mr. Wyone seems to doubt that the ridges in Bombay were ever the 

 result of trap intrusions under the sedimentary beds, but the dome shajK'' 

 appearance and the variations in the height of the lower trap extensively exposed 

 at Sewri seem to favour the view that the ridges were at least partially due 

 to that cause. Even at Worli there are indications that the sedimentary 

 rocks have been Ufted up in a dome. Dr. Buist in speaking of the Love 

 Grove beds in the paper on the geology of Bombay read before the Bombay 

 Geographical Society in 1851 says : " Just at the sluices the regularity of 

 the beds has been disturbed, and they dip a little in all directions." The 

 inference is clearly that the beds were ' raised in a dome.' 



Sedimentary beds dipping south, Worli. 



The physical characters of this ^^^J^\:1:^V^L:\^' ^^^^ 

 that caps the other ndges ^"/"^.Sstanding the apparent difference 

 crystallme and fine grained. Yet notw^hstand^^ JV- ^^^^ ^^^^ ., 



this basaltic trap is one and the same 



