320 Nctes illustrative of iJie Geology of Southern India. [April 



porcelain is made, remains. It is a curious facf,and one which requires 

 farther examination than it has received, that if this mixture be Buffered 

 to remain long at rest, before it is worked up, it becomes useless : for 

 it is then found, that the silex, which at first was uniformly mixed, 

 becomes aggregated together in small lumps. This parallel," he 

 adds, " to the formation of flint in the chalk strata deserves atten- 

 tion."* Could an analogous observation to this, on the aggregation of 

 the constituents of minerals in a state of igneous fluidity be obtained, 

 a most important light would be thrown on their occurrence in detach- 

 ed and massive portions in rocks of igneous origin. In the present, 

 as in many other instances, geology must claim this boon from the sis- 

 ter science of chemistry. 



At Mallepandy, a village about ten or twelve miles from Kisnagherry, 

 a beautiful specimen of epidote, of the usual dark green colour, was 

 found imbedded in a mass of true granite, which was here observed, 

 though not to any considerable extent. The sienite was found to be 

 peculiarly large grained, and the crystals both of the hornblende and 

 felspar distinctly defined; on one fragment of the rock, which had been 

 precipitated from the higher ground, a large quantity of iron pyrites 

 in cubical crystals was observed. The country between this village 

 and Wanianabaddy presents the same general features, veins of por- 

 phyry outcrop at about a mile from the latter place, exhibiting occa- 

 sionally small nests of chlorite. The road in many places passes over 

 the underlying granite, which is more abundant here than usual, and 

 the large quantity of mica scattered over its surface causes it to glitter 

 in the light of the sun like burnished silver. Many water-worn frag- 

 ments of different rocks, greenstone, basalt, compact and vescicular, 

 reddish coloured sienite, so small grained as readily to be mistaken for 

 sandstone, are found strewed over the sandy plain surrounding Wani- 

 anabaddv. They are brought most probably from the distant hills by 

 the Palar river, which during the moonsoon comes down with great 

 violence, and often devastates the adjoining country. 



The aspect of the valley between Wanianabaddy and Amboor is 

 monotonous and uninteresting. At the latter place I was much inter- 

 ested by the marked development of the phenomena of crystallisation 

 in the structure of the. trap dykes, which traverse the neighbouring 



* Note. Will carbonate of lime treated as above vr\i\\ alumina segregate similarly to 

 silex? If it does, then may not the occurrence of layers of nodular kunkar in clay be 

 explained on the same principle as the occurrence of like layers of flint in chalk ? The 

 question admits of aa experimental reply, and an effort to obtain this is now in progress, 

 R. B. S. 



