THE011Y OF THE EAKTH. 



der the sea ; and because, on that account, they 

 cannot serve ns as a measure of the time which 

 has elapsed since its last retreat. 



Additions of Land by the Action of Rivers. 



MM. Deluc and Dolomieu have most care- 

 fully examined the progress of the formation of 

 new ground by means of matters washed down 

 by rivers ; and although exceedingly opposed to 

 each other on many points of the Theory of the 

 Earth, they agree in this. These formations aug- 

 ment very rapidly ; they must have increased still 

 more rapidly at first, when the mountains fur- 

 nished more materials to the rivers, and yet their 

 extent is still inconsiderable. 



Dolomieu's Memoir respecting Egypt * tends 

 to prove, that the tongue of land on which Alex- 

 ander caused his city to be built, did not exist in 

 the days of Homer ; that they were then able to 

 navigate directly from the island of Pharos into 

 the gulf afterwards called Lake Mareotis ; and 

 that this gulf was then, as indicated by Mene- 

 laus, from fifteen to twenty leagues in length. 

 It had, therefore, only required the nine hundred 

 years that elapsed between the time of Homer 

 and that of Strabo, to bring things to the state in 



* Journal de Physique, t. xlii, p. 40. et seq. 



