30 FOOTE : GEOLOGY OF MADURA AND TINNEVELLY DISTRICTS. 



and a couple of miles further south rise the several fine sharp-peaked 

 Narayanan Pottai out- ^^^^^ iovmiug the Narayanan Pottai ridge north 

 ci'op- of the road leading from Nanganeri to Kalkad 



(Caleaud). Narayanan Pottai, which must be at least 1,000 feet high, 

 consists of a garnetiferous granite gneiss offering no special characters. 

 The beds have a well marked southerly dip. Outcrops of the easterly 

 extension of this series are to be seen 4 miles to the east-south-east of 

 Nanganeri at Pottaiyadi, and 6 miles further on to the north and east 

 at Vijayanarayanam (Visionaurainum) where the strike of the beds 

 trends from east-south-east to east-north-east. . 



About 2| miles south of Nanganeri rises another ridge parallel with 

 Outcrops south of ^^® ^^^^ named. In the hill forming the western 

 Nanganeri. ^^^^ q£ ^}^g ridge a series of typical " Cape Como- 



rin " gneiss beds is exposed ; the beds lying at remarkably low angles 

 only from 10° to 30° south. As seen from the north, the bedding is 

 so wonderfully clear and well preserved that it is very difficult to 

 realise that one is looking at beds of a highly metamorphie rock. 

 The easterly extension of the ridge shows an underlying set of 

 highly granitoid beds in which the bedding is by no means strik- 

 ingly developed. To the south of the Tirukurungudi (Tricknaun goody) 



river and west of the high road from Nanganeri 

 Tirukurungudi hills. i s • 



to Panagudi (Punnaugoody) is a remarkable 



cluster of bare rocky hills of banded granite gneiss, the most south- 

 westerly of which the Suttu Pottai, or Tirukurungudi hill, forms a 

 noble conical mass rising from 1,2-00 to 1,500 feet above the plain. It is 

 the most nearly perfect cone I have ever seen in crystalline rocks, 

 and to all appearance quite inaccessible ; a legend exists, however, that 

 it was once scaled by a young native at the instigation of the Trigono- 

 metrical Survey people, who followed him up by means of ropes and 

 established a Trigonometrical Station on the top. No remains of the 

 station are now visible from below. The bedded character of the gneiss 

 is made visible by bands of different colour crossing the bare rocky base 

 of the cone on the northern side. Good shows of similar banded 

 ( 30 )• 



