VOLCANOES OF THE PHILIPPINES. 



249 



no lavas. The last outburst in 188Ô destroyed all traces of vegetation in the 



island. 



Bombon, which is nearly 640 feet deep, was probably a vast crater, of which 

 the islet with its three volcanoes is merely the central cone, while the walls of tufa, 

 over 600 feet high, encircling the north and east shores of the lake, are the remains 



Fig. 109.— Lake Bombon. 

 Scale 1 : 300,000. 



6 Miles. 



of the original rim of the crater. But, like that of the island of Saint Paul, this 

 crater was formerly open towards the sea, as shown by the present intervening barrier, 

 which is entirely composed of eruptive scorige. The water of the old inlet, thus 

 converted into a lake, is still somewhat saline, although constantly renewed by rain 

 water, and although the overflow is carried off by an emissary running south-west 

 to the coast. The marine fauna inhabiting the lake has gradually adapted itself 



