86 GEOLOGY OF THE SON VALLEY, ETC. 



d. — Finer-grained lavas, altered basalt {melaphyre). 

 There is every gradation from these diabases to the finer-grained 

 altered basalts or melaphyres. The greatly altered rock T y T men- 

 tioned above on page 8 1 is already fine-grained 



Melaphyres. # 



enough to deserve that appellation. No other 

 rock observed in the Son region exhibits such a degree of alteration, 



s - .. k . but some of the rocks from the Jabalpur outcrop 



Jabaipur. f the Bijawars are very similar, for instance, 



ToV> "nfV anc * It* iVg * s somewhat schistose and coarser-grained than 

 7Fr« The felspar seldom shows any traces of its original crystal 

 outlines. The hornblende is fibrous, bent and curved giving wavy 

 extinction. There are patches of chlorite associated with well- 

 shaped epidote crystals. The chlorite does not form a felted scaly 

 aggregate, but is in crystallographic continuity over the whole area 

 of the patches. It may have grown in the place of some pre-existing 

 porphyritic constituent as we shall find to be the case in another 

 melaphyre from Dholki in the Son region. There are numerous 

 patches of leucoxene. 



-f^ shows nothing but a very fine-grained felted aggregate of fibrous 

 hornblende and minutely granular felspar. Almost all the hornblende 

 fibres are more or less curved. There are secondary quartz and calcite, 

 and little or no trace remains of the original structure. |£ is sti U 

 finer-grained. The hand-specimen is greyish-green. It consists of 

 green hornblende in minute fibres, felspar, leucoxene, chlorite and 

 epidote. The structure is not entirely obliterated and the felspar 

 microliths can still be discerned. 



Returning now to the Son region, there is a very similar rock 

 from Deora, -j-fro collected by Mr. Bose. It 



Son region. 



belongs to the more northern of two great 

 volcanic outcrops represented on figure 5. It is a schistose scoria- 

 ceous melaphyre. The hand-specimen is of green colour and is 

 speckled with small rounded masses of chlorite. It also shows 

 elongated masses of calcite with a flattened elliptical section. These 

 ( 86 ) 



