582 

 THE GEOLOGY OF WORLI HILL. 



BY 



Jayme Ribeiro, Esq., L.C.E. 



With one plate and three text figures, 



(Paper read before the Bombay Natural History Society 

 on 2Qth February 1920.) 



A glance at the map of Bombay shows the greater part of the western coast 

 of the Island skirted by a range of hills. It starts from the northern horn of the 

 Back Bay and after running in a northerly direction ends at the southern bound- 

 ary of the Mahim Bay to re-appear beyond the limits of the city as the promon- 

 tory on which stands the Chapel of Nossa Senhora de Monte. The range, 

 however, is not a continuous one, nor of a uniform height. There is a consider- 

 able break of about 2,300 feet at Mahaluxmi. The small knoll on which 

 stands the tomb of Haji Ah, a Mahomedan saint of considerable repute, marks 

 practically the centre of this vanished portion of the range. The section on 

 the south of the breach is made up of the Malabar and CumbaUa HiUs which 

 at some points attain the height of about 220 feet. The northern section 

 starts with the mound on which stands the tomb of Mama Hajiani and runs 

 in an imdulating manner, now dipping to the level plain now rising to form 

 other hillocks till it ends at the WorU Fort. This section of the range is known 

 as the Worli Hill. It formed by itself one of the seven islands which originally 

 went to make up our present city. 



It is interesting to watch, as one travels by the B. B. & C. I. Ry. from Grant 

 Road to Lower Parel stations, the central portion of this range with its badly 

 scarped sides and its top dotted with bimgalows and fringed with brab palms. 

 Just as the train leaves the Mahaluxmi station there appears, on the north of 

 the Love Grove Sewage pumping station, a part of the hill reddish brown in its 

 upper and ashy grey in its lower portions. This is the part of the range that 

 is going to take up the greater and more interesting section of this paper. 



Apart from the similar physical aspects of the two sections of the range there 

 are strong geological evidences to show that these two sections are identical in 

 their origin and that at some remote period the sea breached the range cutting 

 it into two. It may be stated here that the description that will be given of 

 the Worli Hill wiU apply in all respects to the northern end of the CumbaUa 

 Hill, the only portion of the southern section of the range that is being quarried 

 at present, with this one difference that I have so far found no fossil remains 

 of any kind at the latter place except bits of charcoal. 



Worli HiU consists of three different strata, the topmost consisting of 

 dark basaltic trap weathering into moorum, the middle of sedimentary beds 

 and the lower of coarse grey trap, each of which strata I shall proceed to 

 describe in detail. What may be the substratum on which these stand is 

 not possible to say in the absence of deep excavations round about the place. 



I. According to Dr. Carter's paper on the Geology of the Island of Bombay 

 read before the B. B. of the Royal Asiatic Society in 1850, the upper stratum, 

 the dark basaltic trap, is " the first of the secondary effusions which caps the 

 main ridges in Bombay, and which, it may be presumed, was once continuous 

 aU over the island." This effusion he assigns to what he classifies as the third 

 period of the geological formations in Bombay, and consequently is subsequent 

 to the deposition of the sedimentary beds which are taken by him to belong 



