1867.] the Western Himalaya and Afghan Mountains. 97 



derived from the boulders brought down by torrents and from those 

 formerly carried down and now imbedded in the Miocene conglo- 

 merates which fringe the base of the Afghan mountains. These 

 boulders and pebbles are mostly greenstone, felstone, trachyte, and 

 porphyry identical with the Himalayan hornblende rock ; and that 

 peculiar variety of amygdaloidal greenstone, pierced with gas-vents, 

 which has been described at No. 4 of the section of the Tukt-i-Suliman 

 in Kashmir, para. 18, occurs in great abundance. (See also PI. x. 

 figs. 1. la.) 



There can be, therefore, no possible doubt that the Afghan mountains 

 were at the Silurian epoch an archipelago of volcanic islands and 

 subaqueous volcanoes ; indeed, they were merely another group of the 

 same great archipelago ; but the fissures or lines on which the vents 

 were situated had a direction N. E., S. W. 



Towards the end of the older Palaeozoic epoch, the volcanoes appear 

 to have subsided in violence, and allowed the waters of the neighbour- 

 ing sea to cool. They did not do so, however, until they had ejected 

 so much lava, scoriae, lapilli, ashes, and debris of the inside of the 

 earth that a great bar, a bar going from the North-west to the 

 South-east and studded with the island-cones of half extinguished 

 volcanoes, had been formed across the sea. A similar bar was 

 produced by the Afghan group of volcanoes, directed N. E., S. W. and 

 the two bars formed a gigantic V, with the angle pointing to 

 the north. On these bars the sea was shallow ; neither was it likely 

 to be very deep between the two branches of the V. The end of the 

 great activity of the volcanoes appears to have been marked by the 

 breaking out of a great number of fumaroles or hot springs, depositing 

 an immense quantity of silica, and forming thick beds of quartzite, some- 

 times pure and clear as glass, sometimes white and opaque as porcelain. 

 We must not forget also, that all analogy points to a general rising 

 of the sea bottom at the north-east of the Himalayan volcanic bar 

 not as a break, but as a gradual and slow upheaval of the earth's 

 crust under the pressure of viscid granite. 



But even these last efforts of the great volcanoes, these bursts of 

 vapours and hot waters, became rare and intermittent, and animals 

 made their appearance in the creeks and bays of the sea between the 

 islands. It was then the dawn of the Carboniferous epoch, and all 



13 



