ScHAiirF — Some RemarAs on the Atlanlk Prohkm. 273 



lying witliin continental limits hare at a comparatively recent (late- 

 been submerged over 1000 fathoms, whilst sea-bottoms now over 



2iOO 



Contour-cliart (after Wild), showing tlie submarine ridge between Madeira and 

 Portugal. The data were furnished from the soundings obtained by the 

 " Challenger," " Gazelle," and " Gettysburg." 



1000 fathoms deep must have been land in part of the Tertiary Era ; 

 but there are a mass of facts, both geological and biological, in 



