STRATIGRAPHY. 5 



may be of later date, the next succeeding formation, in point of age, 

 is the intrusive granite. This, as will be seen from the map, is 

 found in two main exposures, respectively north and south of the 

 transition area, and bounded on their north and south margins by 

 newer rocks: Vindhyans to the north and Gondwanas to the south. 

 Of the relation of the crystallines to these newer sedimentary 

 formations there is no doubt, in both cases there is a marked uncon- 

 formity, the crystallines having been uplifted, denuded and then 

 covered by newer deposits. The junction of the crystallines with 

 the transition rocks is less definite and even open to the possibility 

 of more than one interpretation. 



Along the whole of the junction of the transition and granitic rocks 

 there is a band, sometimes reaching two or three miles in width, 

 where the gneissose and schistose rocks occur intermixed, and in 

 the few sections exposed in stream-beds the gneiss is seen to occur 

 in veins or bands running more or less parallel with the foliation 

 of the schists. Sections of this nature were at one time held to 

 indicate an interbedding of gneiss and schist and to prove the 

 conformity of the two series; the interpretation is not, however, 

 now in favour, and in the area under description there are, in 

 spite of the imperfection of the contact sections, indications that 

 this is not the true interpretation. 



In the first place there is the evidence of contact metamorphism 

 Not only do the transition slates become dis- 



Contact metamor- .. .. ... , 



phism. tinctly more schistose as the granitic masses 



are approached, but in the sections occasionally 

 seen in stream-beds, it is seen that the schistosity often increases 

 markedly in the immediate neighbourhood of the gneissose bands, 

 indicating that the latter had been injected in a heated condition 

 and caused a certain amount of local change in the rocks they 

 invaded. Secondly, it is seen, in these sections, that the gneissose 

 bands do not invariably follow the foliation of the transitions, but 

 occasionally cut across it ; the foliation having in this case been 

 developed parallel with the bedding planes. Thirdly, inclusions of 

 schist are found in the bands of gneiss. 



( 5 ) 



