I]S^TRODUCTION 251 



object of more or less detailed descrij^tion and ilhistration, by a long line 

 of foremost geologists, for more tban a century and a half. Further- 

 more, it is unusual among volcanoes in presenting some permanent topo- 

 g'raphic features which are invaluable as points of reference for locating 

 the several foci of activity at different times. These are the Filo del 

 Zolfo, which bounds it on the northeast, and. the Torreone or Filone di 

 Baraonda, its southwestern boundary. Volcanic activity, at least within 

 historic times, seems to have been confined to the area between these 

 ridges, and the Uxo are so prominent and distinctly outlined tliat one or 

 the other (or both) will naturally be mentioned in descriptions or appear 

 in most maps or illustrations. Finally, even in times of great activity, 

 observation of the crater terrace is possible. 



In this respect Stromboli differs from such volcanoes as Vesuvius and 

 Etna, whose craters are approximately circular and vary constantly in 

 size, depth, outline, and rim profile, so as to present no permanent and 

 identifiable points of reference for any great length of time by which the 

 positions of vents in the crater floor may be compared at different dates. 

 ]n spite of these difficulties there is some evidence that also at these 

 volcanoes a tendency to a certain persistence in location of vents may be 

 made out. At Kilauea the san^ tendency may be discerned Avith even 

 greater probability. These volcanoes will be discussed later. 



Stromboli 



As the location of the different vents is what concerns us here, the 

 varying types of activity at them will not be described in this paper; 

 :also attention will be directed especially to the evidence presented by the 

 sketches and maps, supplemented to some extent by that of verbal de- 

 scriptions. 



The crater was visited by me on August 7 and 12, 1914, on the latter 

 date in company with Dr. S. Kozu, of Tohoku University. A brief 

 description was published last year.^ A vicAv of the Sciarra Avith the 

 orater terrace above, taken from the sea on August 14 by Doctor Day, is 

 shoAvn in plate 6, AA-hile plate 7 shoAA^s the terrace as seen on August 12 

 from a point above looking north. ^ The perspective of this vicAv is mis- 

 leading, because of the doAvuAvard tilting of the camera. What appears 

 to be a high, dark ridge is really a plain and Ioav, elongated dome, part 

 of the crater floor or terrace, some 200 meters below the observer. A 

 sketch plan^ of the terrace is given in figure 1. 



Washington and Day : BuU. Geol. Soc. Am., vol. 26, 191.5, p. 387. 



This is not the same view as that shown in plate 24 of the paper just cited. 



This is reproduced from figure 1 of the paper cited. 



