Russell — Massive-Solid Volcanic Eruptions. 255 



evidence tending to show that, as suggested by Darwin, " the 

 Peak is part of a great dike, the only remnants of which now 

 exposed are the upper portions of the Peak itself, and the 

 columns at the Horta do Pico, a short distance to the south-west." 

 In the case of the buttes of the Deccan trap region of India, 

 and of the Peak of Fernando de Noronha, the suggestions 

 that have been offered in reference to their being of the same 

 type as the obelisk of Pele, are based almost entirely on simi- 

 larity of form ; but something more than this is evidently 

 required before similarity of origin can be considered as estab- 

 lished. In the study of topographic forms of the nature of 

 those in question, it is essential that criteria for their classifica- 

 tion should be formulated. An attempt in this direction will 

 be made later in this article, after which the places to be 

 assigned the monumental forms brought to the front .by 

 Strachey and Branner will be considered. 



4 'jmis* A-tjj&e: 



Fig. 1. Panum Crater, Mono Lake, California. 

 (Reproduced from the Eighth Annual Eeport of the U. S. Geological 



Survey. ) 



It is not necessary to go to India and Brazil, however, to 

 find illustrations of massive-solid volcanic eruptions of the 

 Pele type, as instructive examples occur among the abundant 

 volcanic records of the United States. 



In the case of the extensive group of recent volcanic craters 

 on the east side of Mono Lake, California, there are several 

 examples of the upward protrusion of highly viscous or essen- 

 tially solid lava which, in at least one instance, rose in a tower- 

 like form to a greater height than the rim of the crater of lapilli 

 which surrounds it. The phenomenon referred to is described 

 as follows in my book entitled u Volcanoes of North America,"* 

 in which the above sketch of Panum crater also appears : 



* Israel C. Eussell : "Volcanoes of North America." The Macmillan 

 Company, New York, 1897, p. 221. The account of the Mono Craters pre- 

 sented in this book is based on an earlier publication by the same author ; 

 namely, " Quaternary History of Mono Valley, California," in the 8th Annual 

 Eeport of the U. S. Geological Survey, Washington, 1889, pp. 378-386. 



