Chap. I.] general sketch of area. 23 



notices may be found of parts of the Salem, Trichinopoly, and South 

 Arcot districts. At page- 692, Captain Lawford is quoted as having 

 observed '^calcareous schists and magnesite'^ at Volconda; the schist was 

 not observed by any of the several members of the Geological Survey who 

 visited that place, and is probably but a local variation of the magnesite : 

 and neither of the rocks have any real connection with the Cretaceous 

 system. At page 641 a notice of the magnesite veins of the " Chalk 

 Hills^^ near Salem, by the late Captain Newbold, is alluded to, in which 

 the association of talcose schists with hornblende schists at Karpur 

 (Caroopoor) is mentioned. 



Other notices of the cretaceous and post-cretaceous rocks have 

 already been reviewed by Mr. Blanford in the first part of this 

 volume. 



Mr. Blanford^s report itself does not call for any remark in these 

 pages, so far as it concerns the Cretaceous rocks, about which he has 

 fully summarized the notices of previous observers, and correlated their 

 views and those acquired during the careful examination of the district. 

 The cretaceous rocks and their relations will therefore demand no further 

 notice from us. It will be seen in the following pages that in some 

 respects our more extended investigation of the district has led to dif- 

 ferent conclusions from those arrived at by Mr. Blanford, — differences 

 not, however, affecting the real value of the results of the survey, nor 

 materially altering the lines of boundary laid down, but restricted to 

 questions regarding the mode of formation and age of one of the 

 formations. 



One or two minor errors of fact ought to be corrected ; 1st. — The 

 great band of granite veins north of the Cauvery is described as extending 

 with undiminished breadth to Caroor. In reality the granite veins are 

 not by any means numerous near Caroor ; they almost totally disappear 

 above the junction of the AmbraAvutty river under alluvium. 2nd.— 

 The height of the Kolamullay (Kolymullays) given at page 34, as 



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