644 meunier: theory of volcanoes 



represents as it were a rudimentary crust, situated, like the 

 earth's crust, between the atmosphere and the nucleus, but as 

 yet in an unstable condition because of its extreme thinness. 

 It exhibits one of the stages through which the lithosphere of 

 our own globe must necessarily have passed. 



The circulation, which (like the circulation of water in the 

 earth's organism) is radial, results from conditions no longer 

 found on our globe, conditions due to the extreme mobility of 

 all the solar elements. Faye notes the production of whirl- 

 winds in the sidereal mass, and he does not hesitate to compare 

 their course and cause to those of the eddies in rapid rivers. 

 The solar eddies, like those of rivers, carry into the depths of 

 the moving fluid the material derived from the peripheral zone, 

 and their descent, though effected in quite a different way, re- 

 minds us of the progressive soaking of the rocks by water, for, 

 like this soaking, it results in producing the mechanical force 

 that is the cause of eruption. Once this relatively cool mate- 

 rial derived from the solar surface has been carried to the proper 

 depth, it is heated, expands, and yields to an enormous pressure 

 tending to shoot it out into the atmosphere, where it forms the 

 rose-colored flames. Evidently it cannot burst forth in this 

 way without carrying with it material derived from relatively 

 lesser depths, especially from the photosphere. This process 

 shows that the solar explosion is an agent for the mixing of sub- 

 stances which by the diversity of their physical properties seemed 

 destined to be forever separated, just as happens in the case of 

 volcanic eruptions on the earth. 



We are not yet in a position to give an exact account of the 

 details exhibited by the volcanic phenomenon at its first ap- 

 pearance, as soon as the necessary conditions were realized on 

 our globe. However, observations of a purely geologic nature 

 show that the upheavals of rocks since the oldest sedimentary 

 epochs are so closely comparable to the work of modern erup- 

 tions as to suggest that the appearance of volcanoes was virtually 

 instantaneous. To gain a clearer view on this point we should 

 have to consider successively the consequences that would flow 

 from the various possible combinations of temperature distri- 



