SOUTH-WEST IRELAND. 197 



that this agency has removed at least 2000 feet in 

 thickness of strata over all the area now occupied by 

 the Hastings beds, a less thickness over the Weald 

 clay area, and still less, in different degrees, over the 

 country now occupied by the greensand and gault. 

 Not very long since, the Hastings beds and Weald 

 clay areas was a forest, the growth of which must 

 have prevented all surface denudation ; and during 

 this Forest age the rainfall must have been a great 

 deal more than it is now. 1 Although the Hastings 

 beds and Weald clay areas were protected by their 

 envelopes of trees, the surrounding chalk downs 

 must have suffered considerably, which seems proved 

 by " the beds of unstratified flint-gravel that are met 

 with in majiy places on the lower greensand, gault, 

 and lower slopes of the chalk." 2 Now, however, 

 although the rainfall has decreased as the forests are 

 gone, atmospheric denudation is acting more or less 

 over the whole area, being accelerated in many 

 places by the tillage of the land. 



The extreme advocates of subaerial denudation may 

 fairly be asked: 1st, Why did the forest grow, and 

 stop the denudation of the Hastings beds and the 

 Weald clay ? 2d, Why are there not accumulations 

 of chalk flints on the Hastings beds and the Weald 

 clay areas, as well as on the gault and greensand ? 



1 See page 113. 2 Foster and Topley, p. 446. 



