DETAILED DESCRIPTIONS OF ROCKS. 6l 



towards the south. The lowest beds exposed on the north side are 

 brick red non-porphyritic rhyolites, similar to those in the hill west of 

 Siwana. These are succeeded by reddish ochrey porphyritic rhyo- 

 lites, which form a spur, steeply scarped on the north face, running out 

 towards the west. In the depression between this spur and the main 

 mass of the hill is a thick band of ash beds, which runs diagonally up 

 the slope to the north of the rhyolite cliffs forming the crest of the hill, 

 and down to the plains on the east side. On this side there appears 

 to be two binds of ash beds separated by a thick flow of rhyolite, but 

 this apparent doubling of the band may be due to faulting or to slip- 

 ping of the beds forming the scarp. The total thickness of the ash 

 beds is about 250 feet. They are succeeded by brownish red rhyolites 

 which are very slightly porphyritic, forming the crest and the whole 

 of the southern portion of the hill. 



In the plain to the east and north-east of the hill last described are 

 several small knolls all of rhyolite, of the ordinary type. At the north- 

 ern edge of one of these, close to the village of Bijli, are two small 

 outcrops of the coarse hornblendic granite, one of which is in contact 

 with the rhyolites, and throws off veins into them. The same granite 

 forms a large mass of hills to the east between Balu and Phulan, but 

 although it is surrounded by exposures of rhyolite, one, immediately 

 north of Balu, of considerable area, the two rocks are nowhere seen in 

 contact. On the south side the rhyolites dip steadily away from the 

 granite at an angle of 30 to south-west, while in the small exposure 

 to the east, between the granite hill and the village of Raki, the clip 

 is from 30 to 35 to the east. Here again the granite seems to have 

 been forced as a dome shaped mass or laccolite among the rhyolites, 

 and to have tilted them up on either side. 



To the south-west of this group of hills another area of granite is 

 found in the hill between Ajiana and Ludrara, and here the relations 

 between the granite and rhyolite are well displayed. The central 

 portion of the hill consists of rhyolites which dip to the north-west at 



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