vi MOUNTAINS 241 



Perhaps the most destructive eruption of 

 modern times has been that on Cosequina. 

 For 25 miles it covered the ground with 

 muddy water 16 feet in depth. The dust 

 and ashes formed a dense cloud, extending 

 over many miles, some of it being carried 20 

 degrees to the west. The total mass ejected 

 has been estimated at 60 milliards of square 

 yards. 



Stromboli, in the Mediterranean (Fig. 23), 

 though only 2500 feet in height, is very im- 

 posing from its superb regularity, and its 

 roots plunge below the surface to a depth of 

 4000 feet. 



It is, moreover, very interesting from the 

 regularity of its action, which has a period 

 of 5 minutes or a little less. On looking 

 down into the crater one sees at a depth of 

 say 300 feet a seething mass of red-hot lava ; 

 this gradually rises, and then explodes, throw- 

 ing up a cloud of vapour and stones, after 

 which it sinks again. So regular is it that 

 the Volcano has been compared to a "flashing" 

 lighthouse, and this wonderful process has 

 been going on for ages. 



