12 HAYDEN AND HATCH: GOLD-FIELDS OF WAINAD. 



which extend from the main mass into the gneiss, frequently run* 

 nin'g across the foliation planes of that rock : 



(6) the absence in these bands or tongues of any foliation, 

 although the surrounding gneiss is well foliated. 



These phenomena may be observed on the ghcit road from Nadu* 

 gani to Carcoor and on the Marpanmudi ridge between Devala and 

 Pandalur, and leave little room for doubt that Mr. Holland's theory 

 of the igneous origin of the charnockites is the true one. 



West of Pandalur, the gneisses become much more hornblendic, 

 and biotite is to a great extent replaced by actinolite, the prevail- 

 ing type being composed of quartz, felspar — with much plagioclase— 

 actinolite and large quantities of zoisite and epidote. Garnet, 

 though rarely absent, occurs in much smaller quantity, while 

 chlorite is common. 



This change is due to the prevalence in this area of a basic 

 felspar-hornblende rock, which occurs in great 



Epidiorita. , _ 



masses on the southern flank of Hadiabetta and 

 elsewhere between Pandalur and Cherambddi. A band occurs also 

 at the waterfall on Hamsluck estate near Devila and was described 

 by Dr. King * as a compact diorite. This rock will be referred to 

 subsequently (p, 16). 



It has already been stated that the gneiss of south- east Waina'd 

 belongs probably to the upper (Bengal) division 



Age of the gneiss. . 



ot the gneisses : these rocks, as seen elsewhere 

 in India, are characterised by the presence of many accessory 

 minerals, amongst which garnet is always prominent, while the 

 members of the lower (Bundelkhand) division are usually of a much 

 simpler and more granitic type and contain but few accessory 

 minerals, which have never yet been found to include garnet. 

 Although the Wainid gneisses show many signs of secondary change, 

 such as the alteration of the felspars into muscovite and epidote, 

 and of garnet into chlorite, yet the abundance of garnet through- 

 out the gneiss points rather to the upper division than to the lower, 



1 Rec Geol. Surv. Ind., Vol. VIII, Pt. 2, p. 38. 

 ( 12 ) 



