25G 



Memoir on the Geology of the 



occupies both the foot of the hills, and many of their summits like- 

 wise ; so hinting at the possibility that the ghauts were elevated after 

 the formation of the laterite.* 



With regard to the question, whether all these three species of 

 stones, which resemble each other, had the same origin, or the conglo- 

 merate kind arose from the disintegration of the unstratified simple 

 species, which we described at the first, I leave to some more fortu- 

 nate geologist to describe, who may have opportunities of visiting, and 

 attentively examining, the localities, where the laterite is found, to 

 decide the momentous question. 



The only information I can contribute I have already given in the 

 foregoing paragraphs ; that is, that in more than one locality, both on 

 the low lands and the hills of India, I have found a modified iron ore, 

 perfectly similar to the laterite, and that, to avoid confusion or doubt, 

 I have called it lateritic iron ore. It is not a rock per se t but the result 

 of a modification in the structure of the metallic ore, which forms not 

 only enormously thick beds and filons, but also whole hills, among the 

 formations of this part of the globe; which modified iron ore, either 

 as such, or in the state of conglomerate, resembles the laterite of Mala- 

 bar, and of the Carnatic. 



I am not positive regarding the existence of manganese on these 

 bills: my friend Colonel Cullen says, that it is found mixed in the iron 

 ore near the lake ; and I found a straggling piece of this ore in the 

 valley of Kaitee (No. 31f)» which I have not analysed, but which has 

 the external characters of one. 



The lowest visible rock of the Neelgh:rries is of the primitive un- 

 stratified class, including true granite, pegmatite, sienitic granite, and 

 hornblende rock : sienitic gneiss, and hornblende slate are occasionally 

 seen, but they belong more to the outskirts of the hills than to the 

 group itself. Besides these rocks, we find granitelle, and a rock com- 

 posed of four minerals, felspar, hornblende, garnets and quartz. 



True granite, composed of felspar, quartz and mica, is not of rare 

 occurrence ; it frequently occupies the summits of the highest hills : thus 

 it is seen in some of the Koondah range, and of the Doodabetta group; 

 I never saw it, except in the form of erratic blocks, in the low valleys 

 (No. 32). In those places it has the usual appearance of immense 

 masses, split by vertical and horizontal fissures, into columnar 

 or prismatic figures; they, however, no where assume the tor-like 



* It would be worth enquiring whether the laterite, mentioned by Dr. Christie as 

 occupying both the coast and the summits of the gbauts, be of the same composition and 

 nature ; because in his account of this rock it seems that he is describing a conglomerate 

 rock ; particularly that in the Darwar district, where he says that, at the summit of the 

 ghauts, the rock is found; is it associated with the hiematitic iron ore, as well as on the 

 Neelgherries 1 



+ Mr. James Pkinsep pronounces this tg be decidedly an ore of manganese.— Ed. 



