GEOLOGY OF CENTRAL INDIA. 



63 



the reguhdr prismatic form alluded to in describing the granites. It either 

 occurs compact or granular, the grains varying from the minutest possible 

 size to the size of a bean, and many of the varieties have a saccharine 

 aspect. These latter exactly resemble, in their external appearance, the 

 very pure white, fine grained, primitive dolomites, with which however 

 they cannot, for a moment, be confounded ; but it was not without minute 

 examination, and subjecting them to the influence of the common native 

 furnace, that I could persuade myself that some of the varieties were- 

 quartz, — they might possibly be confounded with some of the varieties of 

 compact felspar. They are slightly translucent. The quartz rock fre- 

 quently appears as if composed of a congeries of large angular masses 

 closely cemented together. This appearance, in a great measure, depends 

 on the seams and cracks Avhich traverse the beds in every direction, divid- 

 ing them into a number of square and rectangular portions. In this last 

 variety, numerous embedded masses of a nearly transparent quartz, form- 

 ing a coarse rock crystal, occur, indeed almost the entire of some of the 

 beds exists in this last form. 



The quartz, on one hand, passes into micaceous schist, which passes 

 again into gneiss, granite, &c. ; and on the other, into argillaceous schist. 

 It first becomes distinctly stratified. It acquires a greyish color, and this 

 color gradually deepens ; it then becomes more slaty in its texture ; mica 

 is sparingly distributed through its substance, and it appears to pass 

 into a harder and more durable variety of argillaceous schist. In many 

 situations, but more especially in the boundary ranges of the valley of 

 Udai/apiir, the connecting link betwixt these two last mentioned series 

 is a rock of a fine granular texture, which occurs distinctly stratified, and 

 has a structure inclining to slaty. Its color is nearly white, and it can 

 with difficulty be scratched by the knife. On exposure, it acquires a 

 beautiful dendritical appearance at the surface, and it passes into a 



