Chap. VI. CASTINGS BLOWN TO LEEWARD. 289 



the trench on the north-east side ; but many- 

 more measurements in other analogous cases 

 would be requisite for a trustworthy result. 



The amount of fine earth brought to the 

 surface under the form of castings, and after- 

 wards transported by the winds accompanied 

 by rain, or that which flows and rolls down 

 an inclined surface, no doubt is small in the 

 course of a few scores of years ; for otherwise 

 all the inequalities in our pasture fields would 

 be smoothed within a much shorter period 

 than appears to be the case. But the amount 

 which is thus transported in the course of 

 thousands of years cannot fail to be consider- 

 able and deserves attention. E. de Beaumont 

 looks at the vegetable mould which every- 

 where covers the land as a fixed line or zero, 

 from which the amount of denudation may 

 be measured.* He ignores the continued 

 formation of fresh mould by the disintegra- 

 tion of the underlying rocks and fragments of 

 rock ; and it is curious to find how much 

 more philosophical were the views, main- 



* " Lecons de Ge'ologie pratique, 1845 ; cinqnieme Lecon.' 

 All llie de Beaumont's arguments are admirably controverted 

 by Prof. A. Geikie in his essay in Transact. Geolog. Soc. of 

 Glasgow, vol. iii. p. IC3, 1868. 



