SKETCH OF ^GINA AND METHANA. 813 



erupted at different points of the region under examination, and 

 it is an important matter to ascertain the relative age of these 

 various outflows. To this problem, unfortunately, I can not fur- 

 nish a very satisfactory or absolutely certain solution, owing to 

 reasons already spoken of and to the scarcity of good exposures 

 and sections ; so that the following remarks merely indicate what 

 I believe (though on slight evidence) to be the true state of 

 affairs. I may express the hope that some future observer will 

 decide the question definitely. 



In the case of TEgina it is probable that the eruptive activity 

 shifted, as a whole, from south to north. That is, the Oros dis- 

 trict is the oldest, followed by the formation of the masses of the 

 Monastery district, and that last of all the hornblende-andesites 

 of the Stavro district were ejected, the formation of Spasmeno 

 Vouno closing the period of eruptive activity on yEgina. This is 

 the general plan, but it is very likely that some of the smaller 

 eruptions, such as those of Anzeiou or Kakoperato, took place 

 during periods when, or between which, the main eruptions of 

 another district were taking place, a fact frequently observed in 

 volcanic regions. 



In Methana the sequence of events is less clear than on 

 JEg'ma, but from analogy with the yEgina rocks and for other 

 reasons, I am inclined to believe that the main andesitic mass of 

 Mt. Chelona was first formed, and that the peaks surrounding it 

 were subsequently ejected. On chemical grounds, which will be 

 discussed on a later page, it seems probable that Methana is, on 

 the whole, younger and more recently formed than zEgina. 



Henry S. Washington. 



(To be continued.) 



