GEOLOGY OF CENTRAL INDIA. 



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granite. In some of these the felspar exists in the form of a soft earthy- 

 substance, (kaolin,) sometimes it is of a reddish color, and at others it is 

 greyish white. The last is frequently granular. 



The country surrounding Tonk is characterised by its numerous 

 detached groups, and the hills often rise into peaks of fantastic form, 

 denticulated ridges, &c. Many of them are entirely destitute of vegetation, 

 and a sharp craggy peak, of a very striking appearance, and crowned by 

 a domed building, overhangs the city. The rocks observed are granitic 

 rocks passing into gneiss, quartz being a very abundant ingredient in 

 these. 



Proceeding N. E. from Tonk towards Sowdli, situated in a pass in the 

 most southern of the two parallel ranges, alluded to in page 85, and distant 

 twenty miles S. W. from Sdhar, the detached hills are still numerous, 

 and many of them are crowned by a strong-hold. The windings of the 

 Sands river are frequently crossed, and the rocks gradually pass into 

 quartz rock, approaching to gneiss, with which hills oi" micaceous and 

 chlorite schists are associated. 



Five miles to the S.W. of a small village called Bopdi, which stands 

 about twenty-six miles S. W. of Soivdli, is a hill fort, of a very imposing 

 appearance. The small detached range, on the highest point of which it is 

 situated, appeared principally composed of quartz of a white color. The 

 lower and central regions of the hills were covered with stunted jungle; 

 the rock then suddenly took a more perpendicular direction, and rose by 

 a very steep acclivity, till, with the slope on the other side, it formed a 

 sharp denticulated ridge, frequently rising into needle-shaped points, and 

 exhibiting a peculiarly bristled aspect. The upper regions of these hills 

 were entirely destitute of vegetation. Many other of the hill ranges 



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