92 



THE WONDERS OF GEOLOGY. Lect. I. 



minarets,* and to reflect that yonder were cultivated fields, 

 that there grew trees, that here were the dwellings of men, 

 and that all have now vanished. The sands of the Desert 

 were in ancient times remote from Egypt ; and the Oases 

 which still appear in the midst of this sterile region, are 

 the remains of fertile soils which formerly extended to the 

 Nile."* 



In the maritime plains and valleys of Peru the same 

 cause is operating slowly, but with unremitting energy ; 

 the sea-sands are marching incessantly before the trade 

 wind, and threaten ultimate desolation. The sand has 

 already surmounted the lofty hills which form the southern 

 boundary of the beautiful valley of Lurin, and is flowing 

 down in large waves over the cultivated ground. The 

 same phenomenon is observable on the elevated plain which 

 is called the Tablada, where the tops of the hills appear 

 like Egyptian oases, and whence the sand is pouring down 

 in enormous floods over the sugar plantations of San Juan 

 and Villa, in the valley of Rimac.f 



46. Formation of recent sandstone in Cornwall. 

 — On many parts of the shores of Scotland, sand-floods 

 have converted tracts of great fertility into barren wastes ; 

 and on the northern coast of Cornwall an extensive district 

 has been covered by drifted sand, which has become con- 

 solidated by the percolation of water holding iron in solu- 

 tion, and in some places forms ranges of low mounds, and 



* See an Essay on the Moving Sands of Africa, in Professor Jamie- 

 son's Translation of Cuviers Theory of the Earth, p. 375. Sir G. 

 Wilkinson, in his highly interesting work, questions the correctness 

 of these inferences, as to the extent of the sand-floods, and assorts, 

 that at the present time the alluvial soil is on the increase, the deposits 

 from the inundations of the Nile more than counter b ala ncin g the 

 inroads of the sands; and that the land now capable of cultivation in 

 the valley of Egypt is greater than at the time of the Pharaohs. 

 Manners and Customs <>f the A ncient Egyptians, vol. i. pp. 218 222 



f Blackwood's Edinburgh Magazine for March; 1831*. 



