ORIGINAL OBSERYERS. 19 



of Egypt, with the view of proving that that country was 

 once a gulf of the sea. 



Xenophanes, a Greek philosopher, a native of Colophon, 

 in Ionia, and founder of the Eleatic sect in Sicily, who 

 flourished 535 B.C., promulgated some speculations which 

 subsequent experience has proved to be correct. He con- 

 tended for the antiquity of the earth, the vital origin of the 

 shells which it entombs, and inferred from their occurrence 

 the previous submergence of the rocks beneath the waters of 

 the sea. 



Aristotle had learned from preceding observers many 

 events which had occurred in the history of our globe, and 

 added valuable observations of his own. Prom these he 

 inferred, with singular accuracy, the nature of some of 

 the most important geological agencies; the filling up of 

 rivers, the formation of deltas, the elevation of certain 

 regions by volcanic agency, the conversion of land to sea, 

 and of sea to land, and the universal law of change, were 

 phenomena with which he was fully and philosophically 

 acquainted. Strabo affords evidence in his writings* of 

 having made still farther advances. In discussing the chief 

 problem of ancient times, the occurrence of fossil shells at 

 great elevations and remote distances from the sea, he cites, 

 among others, the explanation of Xanthus the Lydian, that 

 the phenomenon in question is occasioned by the diminu- 

 tion and retirement of the sea, in a manner analogous 

 to the drying up of rivers, lakes, and wells, in seasons of 

 drought. The philosophic geographer, however, .repels this 

 and a similar hypothesis of seas having burst their barriers 

 and formed new channels, and offers in explanation a theory 

 which, in substance, has been adopted by modern philoso- 

 phers, and proved by indisputable evidence to be correct. 

 He boldly asserts that the cause is to be sought, not in 

 changes of the sea, but of the land, After stating the 

 great probability of a considerable portion of the existing 

 continents having been successively sunk beneath and raised 

 above the level of the ocean, he adds, " The same land ia 

 sometimes upheaved, and sometimes depressed, and the sea 

 also is similarly affected. We must, therefore, ascribe the 



* Sec his Geography, book ii. chap. 3. 



c2 



