EXPLANATION OF THE PLATES. 



Introductory Notice, and Description of the Geological 

 Phenomena illustrated by Plate I. 



Plate 1, 



Is an imaginary Section constructed to express, by the 

 insertion of names, and colours, the relative positions of the 

 most important classes, both of unstratified and stratified 

 rocks, as far as they have yet been ascertained. It is found- 

 ed on many series of accurate observations, on several lines 

 taken across Europe, between the British islands and the 

 Mediterranean Sea. Although no single straight line exhi- 

 bits every formation complete in the full order of succession 

 here represented, no fact is inserted for which authority 

 cannot be found. The near approximation of this synoptic 

 representation to the facts exhibited by an actual section, 

 may be estimated by comparing it with the admirable sec- 

 tion across Europe, published by Mr. Conybeare in the Re- 

 port of the Proceedings of the British Association for the 

 Advancement of Science, 1832, and with his sections of 

 England, in Phillips and Conybeare's Geology of England 

 and Wales. 



The chief merit of the above Section is due to the Ta- 

 lents of Mr. Thomas Webster; it is founded on a more 

 simple section which has for several years been used by 

 him in his lectures, and which exhibits the relations of 

 the Granitic and Volcanic rocks to the stratified formations, 



vol. 11. 1 



