John Michell 22, 



table which seems to have been drawn up by him about 

 1788 or 1789, and which was published after his death. 1 



Michell enables us to form a clear conception of his 

 views by the following illustration. "Let a number of 

 leaves of paper," he remarks, " of several different sorts or 

 colours, be pasted upon one another ; then bending them 

 up into a ridge in the middle, conceive them to be reduced 

 again to a level surface, by a plane so passing through 

 them as to cut off all the part that has been raised. Let 

 the middle now be again raised a little, and this will be a 

 good general representation of most, if not all, large tracts 

 of mountainous countries, together with the parts adjacent, 

 throughout the whole world. From this formation of the 

 earth it will follow that we ought to meet with the same 

 kinds of earths, stones, and minerals, appearing at the 

 surface in long narrow slips, and lying parallel to the 

 greatest rise of any long ridge of mountains ; and so, in 

 fact, we find them." 



Contrast this clear presentation of the tectonic struc- 

 ture of our mountains and continents with the confused 

 and contradictory explanation of the same structure sub- 

 sequently promulgated from Freiberg. Michell clearly 

 realized that the rocks of the earth's crust had been laid 

 down in a definite order, that they had been uplifted 

 along the mountain axes, that they had been subsequently 

 planed down, and that their present disposition in parallel 

 bands was the result partly of the upheaval and partly of 

 the denudation. 



The establishment of stratigraphy in England, and of 

 the stratigraphical sequence of the Secondary, or at least 



1 See Phil. Mag. vol. xxxvi. p. 102. 



