28 POOTE : GEOLOGY OF MADURA AND TINNEVELLY DISTRICTS. 



brongbt apparently from the lowest granular quartz band to the north 

 of Tirumang-alam in Madura district. In another case in the south of 

 Trichiuopoly district traces of dark blackish-green mica in extremely 

 small scales could be made out. Although the bedded character of the 

 rock is generally very obvious, these quartzose beds have often been 

 mistaken for large reefs of vein quartz and have given rise to many 

 hopes of their turning out aariferous. In the proximity of these beds the 

 general surface of the country is often largely covered with very character- 

 istic reddish angular debris. Such is very markedly the ease all round 

 Palamcotta. Beds of similar character were noted in Northern Travancore 

 by my colleague, Dr. King, and in Southern Travancore by myself. 

 As in the Madura country, the Tinnevelly granular quartz bands 



Intercalation with ^re always found to be under and overlaid by 

 gniiiite gneiss band. bands of various thickness of typical granitoid 



gneiss, which owing to its greater susceptibility to weather action 

 has almost everywhere been more extensively denuded, and is therefore 

 very frequently marked by the superficial deposits. Outcrops of the 

 granite gneiss are to be seen at Paraipatti ( I'auraeputty) 2 miles 

 north of the Kadambur Railway Station and to the west of Ottapiddaram 

 within the apex of the triangle described by the granular quartz beds 

 {vide map). Grranite gneiss beds are exposed also in several places, 

 south-east and south-west of the apex of the triangle just named, e.gr. 

 at Dalavaipuram (ThuUavaupoorura). 



As already stated above, the gneiss of the region south of the Sangani- 



Cape Coraorin type of Sevandipatti and Vallanad granular quartz bauds 

 granitoid gneiss. -g pve- eminently granitoid. The most noteworthy 



type among the granitoid gneiss is a pale quartzo-felspathic banded rock 

 with a small quantity of black mica (very rarely of hornblende and very 

 numerous small pale red or pink garnets. From its having been first 

 noted near Cape Coraorin where it occurs very largely, I designated it 

 the Cape Comorin type. Granitoid gneiss of this type is also very 

 common in the tract south of Tirumangalam intermediate between the 

 Madura and Tinnevelly granular quartz bauds. Striking examples of 

 ( 28 ) 



