16 HAYDEN AND HATCH ; GOLD-FIELDS OF WAtNAD. 



(a) The older basic intrusives have already been mentioned as 



occurring in the gneiss near Devdla and Panda- 

 Older basic. , .... 



Iur. 1 hese may be classed as epidiontes 



(PI- 3) fig« 4)- They are composed of felspar and hornblende, with 



few accessory minerals. 



The felspar is always much altered and is full of grains of epidote : 



when sufficiently unaltered to be determined it 

 Felspar. m ... 



is found to have been originally a plagioclase 

 probably oligoclase. 



Hornblende. The hornblende is a common green actinolite. 



Other minerals present are sphene t r -utile ', zoisite, garnet (rare), 



and chlorite. Biotite is common in the intrusive 



Accessory minerals. . 



mass on the southern flank of Hadiabetta. 



Portions of the rock as seen on Hadiabetta are composed entirely 

 of dark green hornblende with a little calcite : these appear to be 

 merely more basic portions or schlieren enclosed in the main mass. 



The band of this rock seen at the waterfall on Hamsluck estate, 

 near Devdla, runs apparently parallel to the strike of the gneiss, but 

 there is little room for doubt that Dr. King was correct in supposing 

 it to be intrusive, and Mr. Holland informs me that a very similar 

 rock was found by himself and by Dr. Walker intrusive in his 

 " Mercara group " of schists and gneisses in Coorg. 



(b) The younger basic dykes are not seen in south-east Waina'd, 



but a broad dyke occurs near Vayitri in south 

 Younger basic dykes. . 



YVainad and below Naduvatam on the road from 



Ootacamund to Gudalur. The rock is in each case a dolerite composed 



of broadly twinned plagioclase felspar — labradorite — and augite. 



The felspar is fresh, but the crystals are often deformed and slightly 



granulated by pressure. The augite is full of black ferruginous dust 



and is usually surrounded by a border of green secondary hornblende. 



In both localities the dykes have suffered from pressure, and fracture, 



accompanied by the formation of mylonite, has taken place in various 



directions through the rock. 



( 16 ) 



