252 



Memoir on the Geology of the 



[Oct. 



torrent, for about a quarter of a mile, we come to a place where the 

 stream is joined by another flowing from the S. W. On both sides 

 of this river (until we come to this junction), the projecting rocks 

 which in some places make up knolls and hillocks, are of the usual 

 sienitic granite, with a good deal of hornblende and a few garnets. 



On fording the river, at the place of junction, we see on the opposite 

 bank all the projecting rocks to have totally changed their character ; 

 they are now cellular, haematitic iron ore, rich in metal (No. 24). 

 That rock is seen protruding through the soil of this and of the next 

 hill (W). Some of the enclosures for cattle on the declivities of this 

 hill are constructed with large masses of the cellular iron ore, which 

 however in some of them has a very compact structure (No. 25). 



The highest of the two hills appears to be entirely formed of this 

 rock, of which huge masses are seen in the intervening ravine. On 

 the summit of the highest hill, the rock assumes a pudding-stone-like 

 Structure, being a hard conglomerate of numerous rounded pieces of 

 ferruginous clay iron ore, strongly agglutinated together by a clayey 

 cement (No. 26). A prodigious number of these rounded pebbles are 

 scattered about, covering nearly the whole of the summit of the hill 

 (No. 27). Many of the hard blocks of this conglomerate resemble very 

 much (if they are not identical with) the laterite of the low lands of 

 India. 



Descending from the summit, along the western declivity of the hill 

 (facing Pinnapal Hill), and only a few yards from the top, the rock 

 insensibly changes its appearance and structure. It becomes by- 

 degrees more compact, and loses its cellular structure ; in short, it 

 assumes the compact appearance of common hsematitic iron ore 

 (No. 28), very rich in iron ; and in this state it continues to the foot of 

 the hill on that side, where some of the projecting masses of this iron 

 ore are flanked by others of sienitic granite, or rather hornblende 

 rock. 



These two hills, on the N. E. side, and at their foot, close to the 

 Stream, are skirted by immense masses of sienitic granite, through 

 which the waters of the river are heard roaring ; except at one place, 

 at the foot of the high hill, where the river is forded to go towards the 

 new road from Neddiwatum to Ootacamund. In that place the iron 

 ore bed crosses the stream ; forms numerous projecting masses on the 

 slope of the opposite hill, having a N. E. direction ; crosses the road 

 of Neddiwatum, and terminates in the summit of the hillock to the 

 N. E. of the road ; beyond the latter place, this rock cannot be traced. 



Now this fllon of iron ore, after crossing the stream of Scotland 

 Valley, is evidently and clearly seen flanked on both sides by sienitic 

 granite, jutting in large blocks through the soil, in the very same way 



