20 GtOLOGv or TRiCHixoroLY, &:c. [Chap. I. 



running from "near Darmahpore south or south-westward, till it ranges 



beyond our limits a little to the north of the Topoor Pass. He points 



veiy clearly to the well marked stratifications of the hornblende schist 



of the hills lying" between Adamancotta and Salem, although in many 



other parts of his notes he fails to recognize the real natui-e of the 



rocks, and confounds gneiss and granite. The subject of the magnesite 



veins near Salem is, on the whole, well treated by Dr. Benza. He 



appears, however, to have overlooked the presence of chalcedony and 



of serpentine in its fibrous form (Baltimorite), which are both of 



common occurrence; and also to have been unaware of the existence of 



the chromate of iron, which forms a remarkable vein in the central part 



of the tract of country covered by these magnesite veins.^ An 



analysis of specimens of this magnesite by James Prinsep, Esq., is quoted 



in an appendix to the paper, the average results of 10 analyses being 



mentioned, as — 



Magnesia ... ... ... 48-34. 



Carbonic acid ... ... 51"66. 



100-00. 



The second locality which he names (on hearsay) as showing an 

 extensive magnesite formation, Yedichicolum, close to the Cauvery, near 

 Trichinopoly, has not been identified during the progress of the survey. 

 It can scarcely be considered to refer to a locality near Tripunguly, 

 described further on, as that is but of small extent, and contains no 

 chromate of iron. The Shevaroys Dr. Benza describes correctly as con- 

 sisting of hornblende slate (schist). The Kunjamullay ('^ Cunjamullay'^) 

 he strangely enough describes as wholly of green-stone slate, (meaning 

 thereby, doubtless, hornblende schist,) overlooking the great magnetic 

 iron beds, by a triple band of which the whole mountain is encu'cled, 

 as well as some other non-hornblendic strata, constituting a great part 

 of the mountain mass. 



* The presence of this was, however; well known to the residents of Salem at that time. 

 ( :M3 ) 



9 



