36 Sketch of a Classljication of the European Rocks. 



recent observations have tended to confirm his previous remarks on 

 four of these epochs. 1st. That the Ezgeberge, the Cote d'Or, fee. 

 have been elevated between the epoch of the Jura limestone and the 

 green-sand and chalk. (Groups 5 and 4 of the annexed Table.) 

 2nd. That the Pyrenees and Apennines were thrown up between 

 the epoch of the chalk and tertiary rocks (Groups 4 and 3.) 3d. 

 That the Western Alps were raised between the tertiary epoch and 

 the first " terrains de transport " (Groups 3 and 2.) 4th. That still 

 later, there was an elevation of mountains, in which were comprised 

 some in Provence, the Central Alps, &.c. 



How far the igneous rocks have been connected with these phse- 

 nomena remains to be seen ; but, as before stated, it is by no means 

 fair to infer that because not seen on the surface they do not exist 

 beneath. Volcanoes, properly so called, both existing and extinct, 

 seem to have exerted a minor influence in the elevation of strata com- 

 pared with that exerted by the igneous rocks which were shot up 

 previous to the action of these volcanoes. Elevations of land do 

 however take place apparently from the causes that produce volca- 

 noes ; and of these the rise of land noticed in Chili by Mrs. Maria 

 Graham, in consequence of the earthquake of 1824, is a striking ex- 

 ample. 



Should the annexed Table succeed in calling the attention of ge- 

 ologists to other divisions than those made in the infancy of the sci- 

 ence, and grounded on particular theories, one supposing three great 

 epochs and a transition between the first and second of these, another 

 considering rocks divisible into two great classes, a primary and sec- 

 ondary, the primary containing organic remains in its upper part, — 

 my object will, as I before stated, be fully answered. We are yet 

 acquainted with so small a portion of the real structure of the earth's 

 exposed surface, that all general classifications of rocks are prema- 

 ture ; and it seems useless to attempt any others than those which are 

 comparatively local, calculated for temporary purposes, and of such a 

 nature as not to impede by an assumption of more knowledge than 

 we possess, the -general advancement of geology. 



