64 LA TOUCHE : GEOLOGY OF WESTERN RAJFUTANA, 



This is the largest continuous mass of rock to the west of the Ara- 

 vallis. On the map it is named Saora, but among the natives this name 

 seems to be confined to the portion, including the highest point, im- 

 mediately south of the village of Golia, situated about midway of the 

 range on the north side. By far the greater part of the hill, including 

 all the higher portion, is composed of the coarse hornblende granite 

 which appears to be everywhere identical in texture except that it 

 is frequently traversed by broad veins of a finer grained rock, or eurite, 

 of the same composition as the surrounding granite. Occasionally 

 these veins contain large porphyritic crystals of pink felspar, and the 

 material then resembles the Malani rhyolites to some extent, but is 

 easily distinguished from the latter by its lighter colour and its less 

 glassy texture. The rhyolites are found in contact with the granite 

 on the spurs all along the northern side of the range, but except for a 

 very short distance near the west end, they do not occur at all on the 

 southern side, where the boundary between the granite and the rh} o- 

 lites forming the hills further south is everywhere concealed by sand- 

 hills. 



At the western end of the range a large area of rhyolite extends 

 from a narrow ravine immediately south of the small village of Jhika, 

 or about four miles to the west. The rhyolite in the whole of this area 

 is very homogeneous in texture, and almost noncrystalline in appear- 

 ance from the large number of felspar crystals and quartz grains 

 which it contains. It weathers into rounded exfoliating masses, so that 

 at a distance it is difficult to distinguish it from the granite. The 

 contact between this rock and the granite is exposed in the ravine 

 south of Jhika. The line of junction runs N. W., S. E., and is quite 

 abrupt and vertical, but it does not appear to be faulted. The bedding 

 of the rhyolites is either horizontal or undulating, but towards the 

 west they dip to the north and north-east at angles varying from 20 to 

 30 degrees. A detached ridge to the north consists of dark red rhyo- 

 lite with few porphyritic crystals, dipping to the northeast. Near the 

 iouth-east end of this ridge a band of strongly porphyritic rhyolite, with 

 ( 64 ) 



