RECENT VOLCANOES. 275 



as it still does in the K6h-i-Tafdan, has been scoured to such an 

 extent by watercourses that it is reduced to isolated masses forming 

 gently sloping plateaux round the periphery of the mountain. 



The original summits of the three cones have been entirely 

 denuded away. The western cone has been denuded to such an 

 extent that it now forms a great circular plain four and a half miles 

 in diameter, surrounded by a beautiful amphitheatre of cliffs. It is 

 an instance of the kind of feature termed by Lyell a " crater of denu- 

 dation." 1 All the drainage of this amphitheatre is gathered into 

 one channel, the Gam-i-Ch^h river. The cliffs that surround this 

 amphitheatre consist almost entirely of accumulated ash-beds (PI* 

 XIV). They do not everywhere rise to the same height in one 

 unbroken line, but have been variously shaped by the agencies of 

 denudation ; some portions which have been less denuded stand out 

 as isolated masses or as outstanding pillars like the Neza-i-Sultdn. 

 Photographs of the latter object, published in the Geographical 

 Journal and the Quarterly Journal of the Geological Society do not 

 show its connection with the surrounding hills and led to some dis- 

 cussion at the time when Captain McMahon read descriptions of 

 the mountain. The Neza is only an unusually lofty mass of ash-beds 

 isolated by denudation. The beds composing it dip south-east at a 

 well-marked angle. 



The second cone seems to have had its centre in the neighbour- 

 hood of the great masses of lava called K6h-i-Abu (PI. XV) and Mi3n 

 Koh. The circular outline of this second cone is less easy to follow 

 on the map (see map 3) than that of the western one, probably 

 on account of its more heterogeneous composition ; for while the 

 western cone consists almost entirely of ash-beds, this second cone 

 contains a large proportion of lavas, principally in its central portion. 

 Moreover, eruptions may have proceeded simultaneously or alter- 

 nately from this cone and from the western one, which would have 

 further contributed to increase its irregularity. 



The eastern cone has been denuded into scarped masses of 



1 Quart. Journ. Geol. Soc, Vol. VI (1850), p. 207. 



H ( 97 ) 



