1835.] Geology of the Bombay Islands. 293 



been termed trappean, or, theoretically, volcanic, as dis- 

 tinguished from the granitic series, or plutonic rocks. 



1. Basalt, occurring in situ at the ruins of a chapel in 

 Salsette; colour, dark-gray, or blackish, with numerous 

 crystals of olivine and augite interspersed ; fracture, irre- 

 gular, dull. The upper portion of the ridges in Salsette 

 appears to consist of this rock, or modifications of it. 



2. Black Basalt, in Elephanta, often presenting a homo- 

 geneous aspect when fractured, but frequently containing 

 minute portions of olivine, sometimes in rounded granules, 

 at other times crystallized ; texture highly indurated. This 

 and the former variety, fuse before the blow pipe per se 

 into a mass resembling pitch stone. The celebrated figure 

 of the elephant, close to the village of Gallipooti, consists 

 of this rock but it appears to be of limited extent. 



3. Amygdaloid, appearing at the great temple of Ele- 

 phanta, possesses a hard wacke basis, containing cavities 

 filled with rock crystal and zeolites, &c, some of which 

 are often met with enclosed in the strong mass in the form 

 of rounded nodules, whose crystalline structure is not appa- 

 rent until they are transversly fractured. The rock has a 

 purplish aspect, and is evidently decaying in many situa- 

 tions, by the readiness with which the atmospherical influ- 

 ences act by the medium of the amygdaloidal cavities. 

 Before the blowpipe per se this rock simulates fused basalt. 



4. Yellowish gray claystone porphyry, at the lower cave 

 of Elephanta. The predominating particles have a yellow 

 resinous appearance, with a black basis. 



5. Green claystone porphyry, appearing at BaboolaTank ; 

 fine-grained, and admitting of a good polish, interspersed 

 with dark-coloured soft particles, which have an even frac- 

 ture, and appear to be small masses of indurated clay. 



6. Amygdaloid, with a light coloured, porphyritic basis 

 and green cavities, accompanied generally with large crystals 

 of calcareous spar, from the neighbourhood of Parell. The 

 calcareous spar is sometimes dark-coloured, probably from 

 the effect of reflected light upon it in its impacted situation. 



7. Numerous large fragments of shell conglomerates may 

 be observed on the shore of Elephanta, consisting of a 

 nucleus of porphyry, or amygdaloid, closely surrounded by 

 adhering bivalves, which afford means of extending the 

 limits of the growth of the mangrove. 



