so passing through them, as to cut off all 

 the part that had been raised ; let the 

 middle now be again raised a little, and 

 this will be a good general representation 

 of most, if not of all mountainous coun- 

 tries together with the parts adjacent, 

 throughout the whole world " (Art. 43). 



This simple but ingeniously contrived 

 model indicates how clearly its author 

 had grasped some of the main facts which 

 modern geology has brought to light. 

 Thus he recognised that the sequence of 

 stratified formations has occasionally been 

 interrupted by upheavals whereby, along 

 certain lines of elevation, these formations 

 have been exposed to the action of the 

 various denuding forces of nature by 

 which, if the denudation continued long 

 enough, the upraised tract would be re- 

 duced approximately to a plane, on which 

 any subsequent deposits would, in modern 

 phrase, lie unconformably. 



From this arrangement of the stratified 

 part of the earth's crust, as he points out, 



43 



