1836.] 



between Madras and the Neilgherries. 



15 



©us incrustations enveloping vegetable substances, when placed in the 

 course of waters abounding with carbonate of lime (No. 49). 

 Many pieces were analogous to the nodular kankar found in the 

 plains of India. From what I shall mention hereafter, it appears that 

 some of the tributary torrents to the Cavery contain a good deal of 

 carbonate of lime. 



The hill of Mysore I could not visit, but judging from some speci- 

 mens I have seen from it, it is formed of granite composed of white 

 and rose coloured quartz, white felspar, black mica and a few 

 garnets (No. 50). 



Nunjengode. — Close toNunjengode flows one of the branches of the 

 Cavery, over which a bridge of fifty-five arches is thrown, and in this 

 place many torrents discharge their waters into it. One of these rivu- 

 lets appears to have its waters overcharged with carbonate of lime, 

 which is deposited all along its course, from its junction with the 

 Cavery upwards. 



Over this torrent, where the road crosses it, there is a small bridge, 

 below which the high banks of the torrent are entirely formed of cal- 

 careous tufa (No. 51). In this spot the deposit is so white, so spongy 

 and light, that it might be taken for pumice. 



A few yards above the bridge of this rivulet we see on both its banks 

 a stratified rock ; it is chlorite slate (No. 52) ; its fracture being dull and 

 earthy, and intersected in an irregular manner by veins of different 

 thickness, both of white quartz and of red felspar, which, with the 

 green of the chlorite, form a very elegant looking stone (No. 53). The 

 red felspar veins, however, do not occur so frequently. 



Among the seams of this chlorite slate, the same kind of calcareous 

 tufa is deposited, which not only penetrates for some lines into the 

 seams, but also projects some lines, and even inches, beyond the surface 

 of the rock, like fungous, or mammillated, excrescences. 



As the strata of the chlorite slate are not in perfect coaptation, the 

 seams gape a little, and the carbonate of lime insinuates itself pretty 

 far into them, so that when the projecting blistered portion of the calca- 

 rious deposition is broken off, a thin stratum of kankar is seen between 

 the strata of the slate, and might be taken as an inter-stratification with 

 them. But, by examination it is soon seen, that this calcarious infiltra- 

 tion does not penetrate beyond a few lines. 



Besides this new kind of kankar, I found, jutting from the soil or 

 loose on the surface, large pieces of the ancient kankar (No. 54), which 

 is very different from the modern, being more compact, semi-crystalline 

 and sparry in the fracture, and concretionary in its structure ; in short, 

 very much resembling the ancient travertino of Italy. 



All the blocks along both sides of the Cavery, and projecting above 



