NILGHIRI HILLS. 227 



para Eoad and the North Western edge of the plateau there are traces of 

 very small trap dykes, which increase in number and 



Trap 00 the Kundabs. 



extent in the neighbourhood of Sispara, the Gneiss 



through which these dykes have penetrated being more quartzose and 



Character of Gneiss at felspathic, and having a more contorted foliation 



^^^^'^^- than that on the Neelgherries ; its general dureetion 



is N. 70 'E. At the same time the laminae of the Gneiss are broader and 



more distinct, especially those of the quartz, which widen out in some places, 



so as to resemble veins of that mineral when seen in detached blocks. 



A mass of trap, some square yards in extent, occurs on the North 



side of the road between the first and second mile- 

 Dyke near Sispara. 



stones from Sispara, having a convex surface, the 



same as that possessed by gueiss, and is only to be distinguished from the 

 latter by the absence of lamination, and its being very much jointed 

 or split up in a direction W. 40. N. It is not very hard, breaking 

 up with plane surfaces, which have a slightly metallic lustre. The 

 boundary between this i-ock and the gneiss is very apparent, but when 

 masses in which the two occur together are broken up, they do not 

 separate at the junction, but split across it in preference. 



On ascending the slope on the Sispara side of the gorge called the 

 Devil's gap, the trap is seen cropping out between 

 the beds o'f gneiss, and sending off branches across 

 the bedding and foliation, or between the laminae of the latter. The 

 gneiss when in contact with these dykes is coarser, and the laminae wider 

 than elsewhere in the vicinity, while the dykes themselves are more split 

 at their surfaces of contact than towards their interior. The widen- 

 ing of the laminae of the gneiss is very well seen at the South- 

 ern end of the small plain of New England, 

 where portions of a trap dyke occur inter-laminat- 

 ed with the gneiss. Here the quartz bands attain a width of 10 or 18 

 inches, but thin out eventually to the ordinary thickness of the lamina." 



