EXPLANATION OF PLATE I. 



and to one another, more intelligibly than I have ever seen 

 expressed elsewhere. This original drawing by Mr. Web- 

 ster has formed the basis of the present enlarged and im- 

 proved section, into which many important additions have 

 been introduced by the joint suggestions of Mr. Webster 

 and myself. The selection and arrangement of the animals 

 and plants is my own ; they have been drawn and engraved 

 (together with a large proportion of the woodcuts) by Mr. J. 

 Fisher, of St. Clements, Oxford. 



For facility of reference, I have numbered the principal 

 groups of stratified rocks represented in the section, accord- 

 ing to their most usual order of succession ; and I have de- 

 signated by letters the crystalline or unstratified rocks, and 

 the injected masses and dikes, as well as the metallic veins, 

 and lines of fracture, producing dislocations or faults. The 

 crowded condition in which all the Phenomena represented 

 in this section, are set together, does not admit of the use 

 of accurate relative proportions, between the stratified rocks 

 and the intruded masses, veins, and dikes by which they 

 are intersected. The adoption of false proportion is, how- 

 ever, unavoidable in these cases, because the veins and dikes 

 would be invisible, unless expressed on a highly exagge- 

 rated scale. The scale of height throughout the whole sec- 

 tion is also infinitely greater than that of breadth. The 

 plants and animals also are figured on no uniform scale. 



The extent of the different formations represented in this 

 section, taking their average width as they occur in Europe, 

 would occupy a breadth of five or six hundred miles. A 

 scale of heights, at all approaching to this scale of breadth, 

 would render the whole almost invisible. The same cause 

 makes it also impossible to express correctly the effect of 

 valleys of denudation, which are often excavated through 

 strata of one formation into those of another subjacent for- 

 mation. 



