80 ERA OF THE TERTIARY FORMATION. 



great swells, forming what are called anticlinal axes, one of 

 which divides the London from the Hampshire basin, while 

 the other passes through the Isle of Wight, both throwing 

 the strata down at a violent inclination towards the north, as 

 if the subterranean disturbing force had waved forward in 

 that direction. The Pyrenees, too, and Alps, have both un- 

 dergone elevation since the deposition of the tertiaries; and in 

 Sicily there are mountains which have risen three thousand 

 feet since the deposition of some of the most recent of these 

 rocks. The general effect of these operations was of course 

 to extend the land surface, and to increase the variety of its 

 features, thus improving the natural drainage, and generally 

 adapting the earth for the reception of higher classes of 

 animals. 



