68 LA TOUCHE : GEOLOGY OF WESTERN RAJPUTANA. 



lavas. The dip of the whole series is to north-north-west at various 

 angles up to 45°. 



About the centre of the range, where the Sukri river breaks 

 through it, a large area of granite is exposed in the bed of the river 

 and its tributaries to the south. This granite is rather coarse grained, 

 containing pink felspar and mica, and is therefore of the Jalor type. It 

 does not rise above the general level of the country as in the case of 

 all the other bosses met with, but is exposed only in the bed and banks 

 of the streams. It is in contact with the rhyolites at one point only, 

 in the bed of the Sukri about a mile south of the village of Darri, and 

 is there clearly intrusive, sending off veins into the lavas and includ- 

 ing blocks of them. A small patch of Aravalli schists occurs a little 

 higher up the same river, near the village of Bhaonagar, but is not 

 seen in contact with either the granite or the rhyolites. The schists 

 have the usual north-east south-west strike, and are nearly vertical. 



The southern portion of the range, to the south of the Sukri, con- 

 sists mainly of a compact black rhyolite with porphyritic crystals of 

 white felspar. It often exhibits beautiful flow-structure. Bands of 

 breccia and agglomerate also occur, and some of the flows are amyg- 

 daloidal. The dips are very varied and it is sometimes impossible to 

 make out any bedding in the rock. It looks as though it had welled 

 out from a fissure parallel to the length of the range; at the base of 

 the hill, on the east side, about a mile south of the village of Malgarh, 

 the lines of flow are vertical, as though the lava had been subjected to 

 lateral pressure while it was being poured out. 



The southern slope of the detached hill north of Chondrai, which 

 appears to be on the continuation of this range, consists of the same 

 black porphyritic rhyolite with a southerly dip. Beneath this, forming 

 the whole of the lower portion of the slope on the north and east 

 sides, a boss of coarse granite containing mica forms a rounded dome 

 supporting the. rhyolites. Along the line of contact it is clearly intru- 

 sive in the latter, throwing off narrow veins into them, and in one place 

 ( 68 ) 



