GEOLOGY OF CENTRAL INDLV. 



61 



The rocks, then, which principally occur are chloritic and argillaceous 

 schists, —greenstone, — greenstone schists, — quartz rock, — -and more rarely, 

 though still in considerable abundance, micaceous schist, granitic 

 rocks,— gneiss, — with occasional beds of serpentine and marble. These 

 rocks pass into each other by insensible degrees, so that it is often 

 difficult to say to which class particular specimens ought to belong. On 

 a general view of the subject I may state, that the argillaceous rocks 

 are more abundant on the southern than in the northern portion of the 

 tract under consideration, while in the latter the granitic rocks, with 

 their accompanying gneisses, micaceous schists, and hornblende rocks, 

 greatly preponderate, — quartz rock being very abundant throughout the 

 whole of Central India. In the neighbourhood of the Dhahar lake, 

 granitic rocks, with gneiss, hornblende rocks, &c. are discovered, and a 

 similar formation, but of no great breadth, may be traced from this, running 

 on a northerly and southerly, or south-easterly direction, through a consi- 

 derable extent of country, the line of continuity being interrupted by 

 the occasional occurrence of rocks of a different nature. This formation 

 may very probably be a continuation of the granitic rocks which occur 

 at Wari, in Guzerat, as described by Captain Stewart. 



The granites have a structure generally intermediate betwixt large 

 and small grained. Their characteristic color is red, but they sometimes 

 occur small grained and of a gr€y color — the color in the red varieties 

 depending on the felspar which usually exhibits a foliated fracture, and 

 which is, generally speaking, the most abundant ingredient. It is 

 sometimes associated with quartz alone, and this variety is generally 

 large grained, the quartz being white and semi-transparent. Passing 

 into the last the common granite is found, and the mica in this varies 

 from nearly black, through olive green, to silver white. I have never met 

 with it in this portion of the country in large plates. To this last, again, 



