Volcano Ôstimn. Idzn. 1 1 



II. Structure and Morphology. 



Structural Outline. 



A general structural idea of the volcano may be formed at 

 a glance. In attempting, however, to discover the inner structuro 

 in detail, much difficulty arises as the mountain is covered with 

 éjecta on its sides and is still youug in dissection. 



Such being the case there seems to be no other way than 

 to conjecture the structure from the exposures on the sea cliffs 

 which afford good natural profiles, as well as from the morpho- 

 graphic features which are so perfectly preserved in their original 

 form, and are consequently so very intimately related with the 

 geologic structure, that they aid us much in the structural inves- 

 tigation. 



It is mainly from these two features that the history of the 

 building up of the volcano has been traced, and the results will 

 be stated in the following chapters. Before the detailed descrip- 

 tions of the structure are given a general summary will be briefly 

 outlined here. 



The volcano is a composite stratified one consisting of double- 

 homates- -a somma and a central one— and is built up of numerous 

 layers, alternately accumulated of rheumatitica and clasmatica of 

 basaltic nature, which have been extruded repeatedly without 

 long intervals of rest between any two successive periods of ex- 

 trusion. 



The somma has several satellitic bodies. On the flanks of 

 the main body of the somma there are many parasitic knobs : 

 Atago^^ (lb), Kazamachi^^ (lb), Mitsumine^^ (la), on the northwest : 



1) ^s 2) m^ 3j H^ 



