Russell — Massive-Solid Volcanic Eruptions. 261 



superficial explosions came movements which broke the rocks 

 on which rests the irregular surface covering within the crater, 

 and apparently an ascent through a distance of a few feet of 

 nearly its entire mass. 



The short list given on the preceding pages, namely, certain 

 of the Mono Craters, Bogosloff, and the nameless crater in 

 Oregon just described, contains all the known or reason- 

 ably inferred examples of massive-solid volcanic eruptions in 

 America, which can be referred to the Pele type. 



With the fresh impetus to the study of volcanoes supplied 

 by the remarkable behavior of Pele, a demand has been made 

 manifest for criteria by means of which the topographic forms 

 produced by massive-solid eruptions can be distinguished from 

 analogous features in the relief of the land. The first step in 

 this direction is the formulation from all available data, aided 

 by reasonable inferences, of a mental conception of the topo- 

 graphic and other characteristics that massive-solid eruptions 

 should present. The facts in hand are sufficient to enable one 

 to make an approximation to such a conception, but the picture 

 will no doubt have to be modified as investigation progresses. 



Table of Analyses. 



Con- 

 stituents. 



No. 1. 



Rhyolite.* 

 Mono Lake. 



No. 2. 

 Hyper- 

 sthenef 



Andesite. 



Monte Pele. 



No. 3. 

 Horn- 

 blende 

 Andesite.} 

 Bogosloff. 



No. 4. 



Phono - 

 lite.§ 



No. 5. 



Basalt. 

 Cinder 

 Buttes. 



si<v__ 



74'05$ 



61*44$ 



56-07$ 



58-02$ 



51-14$ 



A1A-- 



.. 13-85 



17-27 



19-06 



20-03 



13-95 



Fe 2 3 | 

 FeO f 



. . trace 



2-53 

 4-18 



5*39 ) 

 0-92 j 



6-18 



2-15 

 12-97 



MgO .. 



.. 0-07 



2-28 



2-12 



0*80 



2*21 



CaO 



0-90 



6-36 



7-70 



1-89 



6-56 



Na 2 G . . 



._ 4-60 



3-54 



4-52 



6-35 



3-59 



K 2 0... 



431 



1-49 



1-24 



6-18 



2-33 



HO... 



_. 2-20 



•88 



0-99 



1-88 



•34 



* Analysis by T. M. Chatard, IT. S. Geological Survey, 8th Annual Report, 

 1886-87, Pt. I, p. 380. 



f Analysis by W. F. Hillebrand, National Geographic Magazine, vol. xiii, 

 July, 1902, p. 291 ; average of three analyses ; minor ingredients as given 

 in original report are not included. 



JG. P. Merrill, Rocks, Rock-Weathering and Soils, p. 84. 



§ G. P. Merrill, Rocks, Rock-Weathering and Soils, p. 80. Average of six 

 analyses given by Zirkel ; includes also MnO, 0'58 per cent. 



I Analysis by W. F. Hillebrand, U. S. Geological Survey, Bull. 199, p. 87: 

 contains also Ti0 2 2*41 per cent ; Zi0 2 0'12 per cent ; MnO 0-44 per cent ; 

 BaO 0-25 per cent ; P 2 5 1'59 per cent; Fl 0-10 per cent ; FeS 2 (S = 0*08) 

 0'15 per cent, and traces of V 2 3 ; NiO ; SrO ; and CI. 



One of the first questions to present itself in searching for 

 criteria by means of which massive-solid can be distinguished 

 from other volcanic eruptions, is : Do the lavas extruded in 



