DETAILED DESCRIPTIONS OF ROCKS. 67 



feet above the sea, or about 1,500 feet above the plain. The elevation of 

 the portion of the range north of the Sukri is much less. The greater 

 part of it is built up of flows of Malani rhyolites of various types with 

 occasional bands of tuff and breccia. The prevailing type in the north- 

 ern portion of the range is a compact rhyolite with well developed 

 flow-structure, sometimes containing vesicles drawn out in the direc- 

 tion of flow. The usual dip is westerly or south of west at angles vary- 

 ing between 25 and 30 degrees. Some angular fragments of a light 

 greenish hornstone occur in places imbedded in these rocks; they are 

 probably fragments ot the underlying slates that have been caught up 

 by the ascending lava and highly altered. 



The only instance yet discovered of a visible junction between the 

 Malani lavas and the underlying Aravalli rocks occurs among these hills 

 in a valley lying about two and a half miles to the south-east of the 

 village of Miniari and 7 miles north of Chanod. The section exposed 

 here has already been described in Chapter III. 1 



A peculiar band of nodular rhyolite occurs among these hills in the 

 detached portion lying to the north of Miniari. The rock is crowded 

 with nodular concretions up to six inches or so in diameter, some of 

 which are almost perfect imitations of fossil shells. 1 he matrix in 

 which they occur is a compact flinty rock with a reddish colour. , Some 

 of the nodules contain cavities filled with crystalline quartz and a little 

 calcite. This is the only instance I have met with in which carbon- 

 ate of lime is associated with the lavas, except the crust of recent 

 origin, which is often formed on the surface of fragments of the lava 

 imbedded in the sandhills. 



A nodular bed also occurs in the isolated hill at Bhaori, about 4 miles 

 to the north-west of Miniari, where it is associated with nearly white 

 slaggy lavas in which scattered blocks of rhyolite are imbedded. A 

 small patch of a friable rusty looking rock with fragments of rhyolite, 

 some of which appear to have been rolled, also occurs among the white 



1 Supra, p. 19. 



( 67 ) 



