8 THE OCEAN. 



which generally characterizes the bottom of the sea. Even rocky 

 coasts, like those of Scotland and Scandinavia, have been levelled here 

 and there in their lower parts, that were not long ago covered by the 

 waters of the Atlantic. If earthquakes and fissures of the soil, vol- 

 canos and slow oscillations of the terrestrial crust, did not on their 

 side increase the inequalities of our planet's surface ; it is certain 

 that the incessant contribution of fluvial deposits, the fragments of 

 rocks worn away by the waves, and above all those remains of swarm- 

 ing organisms which fill the sea, would have effected as an inevitable 

 result the equalization of the ocean-beds, and the transformation of 

 their abysses into scarcely indicated slopes ; the waters, on their side, 

 would gradually invade the surface of the continents, till, after the 

 operations of myriads of centuries, the earth would become again 

 what it formerly was, a spheroid with its surface entirely covered 

 by a bed of water of uniform thickness. 



According to an ancient popular opinion, which, in default of 

 direct observation, was not more contradictory to good sense than 

 many other hypotheses called scientific, the sea was " bottomless ; " 

 and this proverbial expression is still that which best conveys to many 

 ignorant persons the real state of things. At the commencement 

 of last century Marsigli himself spoke of " the abyss " of the Mediter- 

 ranean as of a gulf absolutely unfathomable.* On the other side, 

 mathematicians, supported by theoretical considerations, have attempted 

 to estimate by calculation the average depth of the seas. Buffon, who 

 does not quote the Italian author from whom he has borrowed his 

 argument, gave to the ocean a depth of water equal to 230 toises, or 

 240 fathoms. t The astronomer Lacaille, whose estimates are no 

 nearer those that recent soundings have rendered probable, allowed 

 from 164 to 273 fathoms of depth to the sea. Laplace, who errone- 

 ously estimated the mean elevation of the land at 3280 feet (that is 

 to say, three times the height now approximately determined),:!: 

 thought that the waters of the sea must also be of about equal 

 depth. Young, drawing his deductions from the theory of the 

 tides, assigned about 2735 fathoms to the waters of the Atlantic, 

 and from about 3250 to 3800 fathoms to those of the South Sea. 

 Arnold Guyot remarked that this depth assigned to the Atlantic, 

 would be in fact that of the trench formed in this marine valley, 

 between the coasts of South America and Africa, having the plateaux 

 of Bolivia on the one hand, and those of the Lupata mountains on the 



* Ui&toire de la Mer, p. 10. t Theorie de la Terre : les Fleuves. 



X Humboldt, See in Vol. I. the section entitled, Harmonies and Contraifs. 





