7$ GEOLOGY OF THE SON VALLEY, ETC. 



Some of the rocks contained in this outcrop have already been 

 noticed (see above, page 40), and it was mentioned that the outcrop 

 was followed for a considerable distance, from Naogai to the west, 

 up to Girwi to the east, and that it extends beyond either point. 

 At Girwi the rocks dip at a high angle in a direction E. of S. 

 The most southern rocks of this outcrop are slates of the usual 

 Bijawar types. Immediately north of them comes a lava-flow, 

 No. T W ; it is a fine-grained greenstone exhibiting distinct schis- 

 tosity in the hand-specimen. The rock differs widely from the 

 Signs of dynamic meta- comparatively unaltered types hitherto men - 

 morphism. tioned, as it affords evidence of considerable 



crushing. In its present condition it consists principally of 

 hornblende and felspar, together with leucoxene, chlorite and 

 epidote. The hornblende is to a large extent fibrous, giving the 

 rock its imperfect schistosity. The felspar shows considerable strain- 

 shadows, and the long-shaped crystals are generally broken up into 

 smaller grains. Those that still retain any indication of their 

 original shape, show by their narrow dimensions that the rock was 

 originally a fine-grained dolerite or coarse basalt. The epidote and 

 chlorite which occur in close association probably represent a further 

 stage of alteration of the hornblende. The specific gravity of the 

 rock is 2*97. 



The two next rocks, T y ¥ and T y ¥ , have a decidedly fragmentary 

 and bedded appearance. Y y T in particular weathers in a manner 

 simulating a coarse conglomerate, the pebbles, however, being quite 

 similar to the matrix. The rocks of this exposure are so highly 

 disturbed that it is difficult to tell whether the structure is an original 

 one, or whether it is due to subsequent brecciation attendant upon 

 folding. 



In the specimen ^i where the fragments are sufficiently small 

 to allow of a number of them appearing in the same microscope 

 section, they often show great differences in coarseness of grain, 

 which maybe taken as a proof of the disconnected and clastic nature 

 of the rock. The best preserved minerals are the felspars. 



( 78 ) 



