EAISED BEACHES. 49 



which still appear in the midst of this sterile 

 region on the remains of fertile soils which 

 formerly extended to the Nile.'* Although the 

 desolation has taken place, it must nevertheless 

 be remembered that the inundations of the Nile 

 are constantly adding to the extent of the alluvial 

 soil, and may, perhaps, be completely counter- 

 balancing the effects produced by the shifting 

 sands. 



But in Peru many of the finest maritime plains 

 and valleys are exposed to desolation from the 

 same causes. It appears that the sand-drift has 

 already surmounted the lofty hills which form the 

 boundary of the valley of Lurin, and is flowing 

 down over the cultivated grounds, threatening 

 their total destruction. The same process is 

 taking place on the elevated plain called the 

 Tablada, where the tops of the hills appear like 

 Egyptian oases, the sand falling in overwhelming 

 floods over the valley of Eimac, to the gradual 

 extinction of the sugar plantations of Villa and 

 San Juan.* 



Other changes in the character and aspect of 

 our sea-shores may here be referred to as having 

 been produced by strictly geological causes. On 

 a great many districts of our sea-shores, as, for 

 instance, from Brighton to Eottingdean, near 

 Bromley in Kent, and Reading in Berkshire, and 

 various other places on the eastern and western 

 coasts of England, and in a variety of localities 



* Blackwood's Magazine, March, 1839. 

 



