and Origin of Mount Etna. 187 



The inclination which has been acquired by some parts of this 

 system of beds, has not been a simple movement of pressure, or 

 the effect of dislocations purely local ; but that of a tumefaction 

 which, in elevating the whole mass of the central gibbosity, has 

 communicated to the lateral portions an oscillatory movement. 



The " soulevemenl"" does not seem to have operated here with 

 the same degree of simplicity as in the localities where it has 

 given rise to regular craters of soulevement^ such as that of the 

 island of Palma, or the circular walls of TenerifTe and the Somma. 

 The effort which has elevated the gibbosity of Etna seems to 

 have acted, not at one sole and central point, but in a straight 

 line, represented by the axis of the ellipse, of which the south- 

 ern, northern, and eastern flanks of the Vol del Bove form part ; 

 and it appears to have acted unequally on different parts of this 

 straight line, so that its western extremity, which corresponds to 

 the present volcanic vent, has been elevated more than all the 

 rest. A similar soulevement could not take place without rup- 

 turing the masses so elevated, and the rents necessarily corres- 

 ponded chiefly with the line of soulevement — either diverging or 

 radiating — of its extremities ; a circumstance which the memoir 

 shews is in accordance with the phenomena as they actually occur. 



The elliptical amphitheatre of the Val del Bove presents, then, 

 all the characters of an irregular crater of soulevement. It re- 

 mains to be ascertained whether this "soulevement" was gradual, 

 or was effected suddenly and at once. The latter supposition 

 alone seems to the author to be admissible. The nearly perfect 

 resemblance which exists between the ejected matters composing 

 the nucleus of the central gibbosity and those which are pro- 

 duced by Etna as the present day, leads to the belief that the 

 volcanic fire acting at the present time is only the continuation 

 of that which produced the ancient volcanic substances. For the 

 fire not being extinct, if the " soulevement" had been gradual, 

 there would have been a continuity and entanglement of the an- 

 cient and modern products; there would not have been that 

 complete discordance of position between them, which constitutes 

 one of the most remarkable features of the structure of Etna.— 

 (Extracted from the Compte Rendu of the meeting of the Aca- 

 demy of Sciences, held on Monday, 30th November 1835.) 



