128 GEOLOGY [CHAP. IX 



Letter 485 abolished craters of elevation. There must be craters of 

 engulfmentj and of explosion (mere modifications of craters 

 of eruption), but craters of denudation are the ones which 

 have given rise to all the discussions. 



Pray give my best thanks to Lady Lyell for her trans- 

 lation, which was as clear as daylight to me, including 

 " leglessness." 



Letter 486 To C. Lyell. 



Down [Nov. 2Oth, 1849]. 



I remembered the passage in E. de B. [Elie de Beaumont] 1 

 and have now re-read it. I have always and do still entirely 

 disbelieve it ; in such a wonderful case he ought to have 

 hammered every inch of rock up to actual junction ; he 

 describes no details of junction, and if I were in your place 

 I would absolutely dispute the fact of junction (or articulation 

 as he oddly calls it) on such evidence. I go farther than 

 you ; I do not believe in the world there is or has been a 

 junction between a dike and stream of lava of exact shape 

 of either (i) or (2) [Fig. 2]. 



If dike gave immediate origin to volcanic vent we should 

 have craters of [an] elliptic shape [Fig. 3]. I believe that when 

 the molten rock in a dike comes near to the surface, some one 

 two or three points will always certainly chance to afford an 

 easier passage upward to the actual surface than along the 

 whole line, and therefore that the dike will be connected (if 

 the whole were bared and dissected) with the vent by a 



1 Elie de Beaumont (1798-1874) was a pupil in the Ecole Poly- 

 technique and afterwards in the Ecole des Mines. In 1820 he accom- 

 panied M. Brochant de Villiers to England in order to study the 

 principles of geological mapping, and to report on the English mines 

 and metallurgical establishments. For several years M. de Beaumont 

 was actively engaged in the preparation of the geological map of France, 

 which was begun in 1825, and in 1835 h succeeded M. B. de Villiers in 

 the Chair of Geology at the Ecole des Mines. In 1853 he was elected 

 Perpetual Secretary of the French Academy, and in 1861 he became 

 Vice-President of the Conseil^ General des Mines and a Grand Officer 

 of the Legion of Honour. Elie de Beaumont is best known among 

 geologists as the author of the Systcmes des Mojitagnes and other 

 publications, in which he put forward his theories on the origin of 

 mountain ranges and on kindred subjects. (Quart. Jouni. Geol. 

 Vol. XXXI. ; Proc., p. xliii, 1875.) 



