186 M. de Beaumont xm the Structure 



vein. As to the upper part of the rent, situated above the point 

 of the flowing out of the lava, it often becomes filled with sco- 

 riae, or substances of "eboulement." Some of these rents, how- 

 ever, have remained open. 



In the eruption of 1832, the phenomenon of the meridional 

 fractures manifested itself accompanied by remarkable circum- 

 stances; and the mass of Etna became completely "etoile." 

 A rent cut in two the platform of the Piano del Lago^ and 

 changed the relative level of its two segments in such a manner 

 as to produce at once a change of form more considerable than 

 had resulted from the products of the eruptions of several ages, 

 which products do not rise higher than two metres round the 

 foundation of the Toore del Filosqfo. This change of relative 

 level shews that Etna does not repose on immoveable founda- 

 tions, and that the segments into which it is divided by the me- 

 ridional rents are susceptible of a certain alteration of position. 

 The walls of the rents being separated, it is evident that the 

 surface of the mountain must have been increased in dimensions, 

 and this enlargement necessarily supposes a tumefaction. The 

 mountain has therefore been elevated, and to an extent which 

 might be easily calculated, if the breadth and length of the fis- 

 sures were exactly known. This elevation is evidently very 

 small, but even its existence is an important fact. 



In examining the nucleus of Etna, the author has noticed a 

 want of relation between the structure of the layers and their in- 

 clination ; a fact diametrically opposed to that which we observe 

 at the present day in all great currents of lava, whose form varies 

 constantly with the amount of the inclination. According to 

 our author, it is evident that those of the layers whose original 

 inclination is changed, are those which at the present day are 

 highly inclined ; and that those which are nearly horizontal have, 

 on the contrary, nearly preserved, relatively to the horizon, their 

 original position^. 



The considerations, of which an analysis has just been given, 

 prove, says the author, in terminating his memoir, that the parts 

 of the layers of the escarpments of the Vol del Bove which are 

 highly incHned, are no longer in the position in which they were 

 originally formed. 



