of a Route from Madras to Bellaty, in 1822. 363 



from below by volcanic agency, from the dead marshy flat in 

 the centre of it. Its base might be 150 yards in diameter, 

 and its perpendicular height about 100 feet. This sienite is 

 composed of large crystals of black hornblende, and yellowish 

 white felspar, very irregularly aggregated, with but little quartz, 

 and that only in patches, and very unequally dispersed. 



The sandstone which has been mentioned was usually found 

 occupying the summits of the hills of clay-slate, and the op- 

 portunities, therefore, of actual examination were but rare. 

 These opportunities occurred also at points very distant from 

 each other, (but, perhaps, not the less corroborative from that 

 circumstance, of the inference that the whole of these ranges 

 are capped with varieties of sandstone,) viz. at Curcumbaddu, 

 in the ghaut close to Baulpilly, in the passage through the 

 range to Cuddapah, in the passage of the Nulla Mulla range, 

 and lastly, in the fourth division, where, from the small ele- 

 vation of the hills, these caps may be traced without the 

 slightest interruption for upwards of five-and-twenty miles. 

 The characters of the sandstone vary from that of a coarse 

 conglomerate, such as that noticed on the route between Nag- 

 gery and Pootoor, to that of the finest grain where it is diffi- 

 cult to distinguish it from quartz or hornstone, into both of 

 which it seemed occasionally to pass. The colours were as 

 various as the texture, being of all shades of red # , white, and 

 green ; some of the varieties met with on crossing the hills to 

 Cuddapah were rather handsome. 



The sandstone forming the cap of the Nulla Mulla hills, 

 where I crossed them between Kistnumchettypitty and Ma- 

 dapurum, was of great thickness, about 300 feet perpendicular, 

 and its acclivity on both sides, the route lying directly over 

 it, extremely steep and difficult. A great deal of rock, much 

 of the same nature as the cap, and interstratified with the clay- 

 slate, prevailed, however, for a space of three or four miles, 

 on both sides of this central ridge, but the clay-slate still con- 

 tinuing by far the most abundant, and in deep wells immedi- 

 ately at the foot of the cap on the east and west sides, exhi- 

 biting that rock alone to the very bottom. The above-noticed 

 were the chief occasions on which the sandstone was observed 

 in extended masses ; but nodules of that rock, as well as con- 

 siderable apparently unconnected masses, were met with in se- 

 veral instances in the valleys, more particularly at the village 

 of Chillumpett, between Codoor and Pollempettah, in the first 

 part of the march from Nundaloor to Wuntimettah, between 

 Poornamila and Alinaggur, in the ditch at Iddamacul, &c. 

 [To be continued.] 



* The red varieties were most common, I think, west from Banaganapilly. 



3 A 2 LXII. A Letter 



