NILGHIRI HILLS. 221 



broken surface. On weathered surfaces the foliated structure is more 

 apparent. In some localities, e. g. at the Seegoor Ghat, the rock weathers 

 into smooth rounded blocks presenting no aiDpearance whatever of 

 Gneissose structure. It is undoubtedly such varieties as this which have 

 been described as Syenite, Greenstone, &c., by Dr. De Benza and other 

 writers. That in reality they are mere abnormal varieties of the foliated 

 rocks is proved by their invariably passing into these latter, and by their 

 never forming veins or exhibiting any appearance of intrusion. A 

 similar hornblendic Gneiss forms the whole of the North-Eastern or 

 loftier portion of the Kundahs, where it is much decomposed, and pro- 

 duces a thick covering of ferruginous clay and lateritic gravel. 



Another very striking variety of the Gneissose rocks, and which 



_ , ^, ^,. has been described as Pegmatite by Dr. De Benza, 



Gneiss of the Koondaiis. jg ^^q Occurring near Sispara in the Koondahs. 



That when seen in a hand specimen only, it bears some resemblance 



to Pegmatite or Graphic Granite, is undeniable, but when seen in 



the mass, it is found to pass gradually into the hornblendic Gneiss 



around, and close examination shows that the peculiar arrangement of the 



Pegmatitic appearance t^o component minerals, quartz and felspar, is 



really due to an imperfect foliation, the lenticular 



threads of quartz being all arranged in the normal direction of the 



foliation. A somewhat similar rock to this, but of finer structure, 



Occurs also to North occurs near Ootakamund, in the valley to the 



N. W. of Daversolabetta or Snowdon* and again 



a much more extensive spread occurs to the North of Mailur forming 



a belt about three miles in width, passing from 

 And at Mailur. ^ '^ 



the foot of the Kundahs to the Kaitee valley 



at the foot of the great ridge of Dodabetta. The last mentioned 



rock contains, in addition to the quartz and felspar, Garnets in great 



quantity. 



^^ So termed by the residents of OotakAuiuud. 



