THEORY OF THE EARTH. 33 



These inclined or vertical strata, which form the 

 ridges of the secondary mountains, do not rest on 

 the horizontal strata of the hills which are situat- 

 ed at their base, and serve as their first steps ; 

 but, on the contrary, are situated underneath 

 them. The latter are placed upon the declivities 

 of the former. When we dig through the horizon- 

 tal strata in the neighbourhood of the inclined 

 strata, the inclined strata are invariably found be- 

 low. Nay sometimes, when the inclined strata are 

 not too much elevated, their summit is surmounted 

 by horizontal strata. The inclined strata are there- 

 fore more ancient than the horizontal strata. And 

 as they must necessarily have been formed in a hori- 

 zontal position, they have been subsequently shift- 

 ed into their inclined or vertical position, and 

 that too before the horizontal strata were placed 



above them. 







Thus the sea, previous to the formation of the 

 horizontal strata, had formed others, which, by 

 some means, have been broken, lifted up, and over- 

 turned in a thousand ways. There had therefore 

 been also at least one change in the basin of that 

 sea which preceded ours ; it had also experienced 

 at least one revolution ; and as several of these in- 

 clined strata which it had formed first, are elevated 

 above the level of the horizontal strata which have 

 succeeded and which surround them, this revolu- 

 tion, while it gave them their present inclination, 

 had also caused them to project above the level of 



