46 GRIESBACH : GEOLOGY OF THE CENTRAL HIMALAYAS. 



position between the cretaceous and the younger middle tertiaries 

 and on the other, indistinct traces of nummulites, determined their 

 geological age accurately. 



The great outburst of basaltic rocks along the Hundes dislocation, 

 between the Manasarawar lakes and Western Hundes, partially hidden 

 under younger tertiaries, is the only "trap" which I have to record 

 as occurring actually within the limits of the area reported on. But 

 in the belt of the Lower Himalayas, as far south as the Siwalik 

 boundary, basic eruptive rocks are frequent, but seem generally to 

 keep in lines parallel to the strike of the flexures, and I have little 

 doubt they occur along lines of dislocations. 



As regards the probable age of the granites, I have nothing 

 Age of granites and Du ^ conjectural evidence to offer. So far it is 

 trapSt certain that the granite must be younger than 



the haimantas, which they penetrate. 



The exact period of its appearance in the Himalayas is far from 

 certain. It is, however, clear that the trap is younger, since it traver- 

 ses the granite in several localities, as for instance, north of Niti in 

 Hundes and elsewhere. Whilst it is certain that much of the basic 

 rocks of Hundes and the Himalayas cannot be much older than 

 miocene, nor younger than these deposits, proved by the vast intru- 

 sions in the upper part of the middle tertiaries of Hundes, we must 

 go to the Hindu Rush and Afghanistan in order to get light thrown 

 on the relations of the granite to the older rocks. 



It is certain that the later mesozoic and tertiary epochs saw im- 

 mense changes taking place in Central Asia. 



Changes in the coast-line of the former continents are traceable 

 in the Perso-Afghin area as low down as the upper carboniferous ; 

 but not until later cretaceous times those vast overlaps take place 

 which caused the unconformity between the upper cretaceous depo- 

 sits and tithonian formations. Again, changes of still vaster nature 

 and extent, this time traceable right across from the Caspian to Tibet, 

 took place in upper miocene times. A great part of Central Asia 

 was covered by middle tertiary seas, whilst within the area indicated, 

 ( 46 ) 



