DEPTH OF THE ATLANTIC. 



15 



the sea is concentric with the surface. Hence the name of " the 

 telegraph plateau,'* given by Maury to these plains, some time before 

 the first transatlantic cable was laid. The most considerable depth 

 of this plateau is 4846 yards, that is to say, about a 1639th of the 

 width of this ocean ; this being a thickness relatively less than that of 

 the finest needle.* The section on Plate III. enables us to compare the 

 relief of the continental surface and that of the oceanic depths from 

 the coasts of the United States to those of Europe. It is true that in 

 order to render the vertical dimensions visible, it has been necessary to 





Pig. 7.— Section of the Atlantic in the Tropics. 



exaggerate them in the enormous proportion of twenty- fold. To the 

 south the depth of the sea becomes more and more varied. An im- 

 aginary section from the plateau of Anahuac to Senegambia across 

 Yucatan, the Caribbean Sea, the Antilles, and the central basin of the 

 tropical Atlantic, presents a much more unequal surface than that of 

 the telegraphic plateau ; but the true oceanic part of the basin equally 

 shows a great uniformity in almost its entire extent. 



Considered as a whole, the North Atlantic is a depression whose 

 sides descend gradually towards a central hollow situated between the 

 coasts of the United States, the Bermudas, and the bank of Newfound- 

 land. A fall of the waters of less than 110 fathoms would reveal the 

 submarine groundwork upon which France, Spain, and the British 

 Isles rest. This is indeed the true foundation of the European con- 

 tinent, for immediately beyond this basement which forms the extreme 

 angle of the Old World, the bed of the sea, at an inclination of about 

 eight degrees, descends gradually from 110 fathoms to 1640 and 2187 

 fathoms below the waves. A fall in its level of 1094 fathoms would 

 * Note. B'lschof, die Gestalt der JErde und der Meeresfidche, p. 6, and following. 



