9>'Z FOOTE : GEOLOGY OF MADURA AND TINNEVELLY DISTEICTS. 



belonging to a smaller bed having a parallel course. A sufficient 

 prolongation of these beds would connect them very probably with the 

 beds from whence was derived the very similar coarse quasi-spathose 

 debris noticed in cousiderable quantity at Palavanattam (Kylassapooram) 

 which was referred to at page 20. 



Two instances of gneissic rocks cropping out from among the lateritic 

 and alluvial beds at a considerable distance from the main gneissic mass 

 require notice. The one occurs below the western scarp of the Sivaganga 

 laierite tract at and north of Mana Madura; the other along the 

 south-western side of the Muddu Kankulam laterite tract {see page 49) 

 immediately east of Kamudi (Kaumoody). In the latter the gneiss 

 is a form (not seen elsewhere in that region) intermediate in structure 

 between a rather ferruginous granular rock and a coarse quartz hsematitic 

 schist. The beds form a low ridge on which stands the old Kamudi fort. 

 The rock which is of a purple-grey colour dips 45° — 50° east-by-north. 



[b) The metamorphic Area in Tinnevelly District. 

 The northern part of Tinnevelly district is so extensively and thick- 

 ly covered with cotton soil that outcrops of the underlying rocks are 

 in many places of very infrequent occurrence. It is particularly the case 

 along the line of the railway and the old Tinnevelly-Madura high-road 

 which run closely parallel to each other for the first 15 miles after enter- 

 ing the Satur taluq. Beginning close north of the town of Virudupatti 

 we find a few small rounded masses of granite gneiss showing up through 

 the cotton soil. Four miles south of Virudupatti the high road crosses 

 a gentle rise from which the general pall of cotton soil has been removed 

 by denudation and a considerable band of granular quartz rock beds 

 revealed. The exposure is, however, too obscure to show much of the real 

 position of the beds. The strike of the rising ground is east to west, but 

 the form of the ground gave the idea that the real disposition of the beds 

 was in form of ananticHnal ellipse, the eastern end of which dips under 

 the alluvium of the Virudupatti river. To the southward of this gra- 

 nular quartz ridge numerous traces of the existence of beds of crystalline 

 ( 22 ) 



