1835.] Geological Sketch of the Neilgherrics. 425 



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

 sienitic granite, with a good deal of hornblende and a fewgai*nets. 



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, hsematitic iron ore, rich in metal 

 (No. 28). 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. 29). 



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. 30). A prodigious number of these rounded 

 pebbles are scattered about, covering nearly the whole of the summit 

 of the hill (No. 31). 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 be- 

 comes by degrees more compact, and loses its cellular structure ; 

 in short, it assumes the compact appearance of common haematitic iron 

 ore (No. 32), 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 Nandiwatam 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 Nandiwatam, 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 filon 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 



