122 NERBTJDDA DISTRICT. 



the granite is approximately parallel to the strike of the metamorphic 



Nature of granite boun- rocks > thou S h not absolutely so. Whenever we 

 danes - find the igneous rock near to the altered bedded 



formations, their relations seem equivocal, a definite line can rarely be 

 drawn between the two, and the transition from one to the other is often 

 imperceptibly graduated. - • 



Lithology of the Granitic Rocks. — The mineral characters of rocks 



included under this head are in our area very various. That variety 



which is most widely spread and occupies the greatest extent of surface 



is a porphyritic syenite whose matrix is a mixture 

 Porpbyritic syenite. , . . 



or glassy quartz with pale pink or pale green felspar, 



along with a small proportion of hornblende, and which contains embedded 



crystals of dull lead grey felspar (ad ularia) about one-third of an inch long, 



and in great number, frequently forming a large proportion of the mass. 



A rock answering more or less closely to this description forms the 

 Gurra hills (see ante, Muddun Mehal Fig. 1) — much local variation in 

 the composition of the mass obtains, and this sometimes to the extent 

 of totally altering the general aspect of the rock. Thus, the adularia 

 crystals are sometimes altogether absent, elsewhere they become so 

 numerous, as to constitute of themselves two-thirds of the rock mass ; 

 again, minute crystals of black mica are found replacing the hornblende, 

 and were in one case noticed along with it, in a hand specimen ; some- 

 times the rock becomes fine-grained syenite without any detached crys- 

 tals and with very little quartz. A good case of this occurs at the second 

 bridge from Jubbulpur on the road thence to Sohagpur where the 

 hornblende is in unusually large proportion. 



The hills near Hinotia village S. of Nursingpur are mostly made up 

 of this syenite porphyry; here the detached crystals are of pink felspar. 



Below Hosungabad much granite is exposed in the banks of the 



Nerbudda, and here also it is mostly either this 

 Red felspar granite. 



syenitic porphyry with pink felspar, or a pink 



