THE GNEISSIC SERIES. 19 



This serial order is, however, to a certain extent, rather arbitrarily 

 made out in accordance with the received scale of metamorphism, the 

 most crystalline rocks being assumed to be the older. The real condition 

 of affairs is that though the schistose groups are to all appearance over- 

 lying the red and grey massive gneisses, yet the much more schistose 

 group (4) is situated between the latter and the group (3) apparently 

 overlying both. There seems, besides, no reason, in this field, to question 

 the succession deduced from varied stages of metamorphism, since this 

 association of the groups is explainable on a faulted position of the 

 younger strata (4) against the massive and older gneisses, or a former 

 condition of extreme unconformity by overlap between the latter and the 

 schistose gneisses. 



Our observations of the crystallines are as yet too few and scattered 

 Correlation with the ^° a dmit of any good attempt being made at a cor- 

 gneiss of India. relation of these Nellore gneisses with others in the 



Peninsula, though it would appear on the whole that they belong to the 

 newer of the two series of the peninsular gneisses, namely, that of the 

 main or eastern area. 1 



At the same time there are many features about the massive 

 gneiss of the Swarnamukhi valley or the granitoid gneiss (1) which 

 point to a comparison with the late Dr. Stoliczka's central gneiss of the 

 Himalayas. 



Subsequent to my survey of this field, I had an opportunity, when 



at home on furlough, of visiting the neighbour- 



With Scottish gneisses. .,,„.. . ,, . , . , , , £ 



hood or inchmaree, m the western highlands or 



Scotland, which has been rendered famous by the controversy between Sir 

 Roderick Murchison and Professor Nicol on the differentiation of the 

 Laurentian and palaeozoic gneisses occurring there ; and as far as observa- 

 tions on the rocks of such immensely separated countries can go, it ap- 

 peared to me that the similarity between the gneiss (Laurentian) of Loch- 

 maree and that of Venkatagiri and Kalahasti is remarkably close, while 

 the schistose group of the Nellore district is comparable with the Silurian 



1 See Manual of the Geology of India, pp. xviii, xix, and p. 17 et seq., Part I. 



( m ) 



