26a 



Memoir on the Geology of the 



is the one which abounds with hornblende and amorphous garnets. 

 These last sometimes are of a large size, and not dispersed through the 

 rock, but, as it were, in nests (No. 77). This rock is very like a speci- 

 men in the museum of the Asiatic Society of Bengal from Norway, 

 marked " large garnets in hornblende." Indeed, I think that there is 

 great analogy between the sienite zirconienne of Norway and this rock 

 of the Neelgherries (No. 78). I remarked in one place of the Dooda- 

 betta group some veins containing quartz and garnets j the last in the 

 granular or resinitic form (No. 7^). 



Before dismissing the subject of the hornblende rock, I must remark, 

 that although this primitive greenstone is occasionally seen on the 

 summit of some hills, in general it occupies the declivities or the lowest 

 parts of them ; and it often assumes a brilliant, laminar crystallization, 

 being then exclusively formed of hornblende (No. 80). I have seen it 

 passing into hornblende slate at the foot of the Neelgherries, at the 

 bottom of the Koonoor pass. Here its strata dip to the east, and I am 

 informed, that the same stratified rock is found at the foot of the 

 same group of hills, to the west, the strata in that place dipping 

 west. It is in those places that this rock occasionally passes into 

 sienitic gneiss. 



The Seven K aim's Hill — Cinnamon-stone. — As I mentioned in a for- 

 mer paragraph of these pages that garnets, which abound in the rocks; 

 of the Neelgherries, sometimes assume the granular form, and, at 

 others, the lamellar structure, striated, and breaking easily " parallel 

 to the plane of the rhombic dodecahedron," I will point out the only 

 place where I found a mineral resembling, in many respects, cinna- 

 mon-stone. I regret not to be able to compare it with the mineral from 

 Ceylon, in my collection, which is at Madras. 



Due north, and about six miles in a straight line from Ootacamund, 

 there is a high hill, having a ridgy summit, running N. W. and S. E. 

 along which seven Kairns, in a line, are erected. At the western foot 

 of this hill, two rivers join, the one from the hills north of Ootacamund, 

 and the other from the S. W. which, having become one, direct their 

 course eastwardly. 



Going from Ootacamund, towards this Seven Kairn's hill, a few hun- 

 dred paces before the junction of these two rivers, a little to the 

 right of the path, we see a small knoll, forty or fifty feet above the 

 level of the river, extending from the S. W. On the uppermost con- 

 vexity of this knoll, are erected two enclosures for cattle, now probably 

 deserted, no human habitation, for miles round the place, being seen. 



The floor of these enclosures is formed by an immense ledge of rock, 

 which, in their interior, is level with the soil, and on the outside, rises 

 a few inches above it. The rock appears unstratified, at least what is 



