134 THREE CRUISES OF THE " BLAKE." 



climate of the arctic regions than it is to-day, and was felt not 

 merely on the coast of Iceland, the Faeroes, Norway, Spitzber- 

 gen, and along the north shore of Siberia, but also in the tem- 

 perature of Greenland, making it possible for a flora similar to 

 that of the temperate zones to flourish there. 



During the tertiary period, the inland sea of Western Asia 

 became greatly reduced in extent ; and the connection between 

 the Indian Ocean and the China Seas, across the central part of 

 China and the northern part of India, Arabia, Asia Minor, and 

 Palestine, closed the free access of the Indian current from the 

 Mediterranean. South America, with the exception of the 

 pampas and Amazonian gulfs, had practically assumed its pre- 

 sent outline ; while the shore line of the southern part of North 

 America had more nearly approached the existing line of the 

 Gulf of Mexico. There was thus a less amount of water heaped 

 up in a smaller Gulf of Mexico, and a corresponding decrease 

 in the influence of the Gulf Stream of the tertiary period over 

 the climate of the arctic region, till in our own epoch the effect 

 of this equatorial current is practicaUy felt only on the eastern 

 part of the North Atlantic, reaching also toward Nova Zembla 

 and the northern shores of Siberia. With the cooling of the 

 arctic region a greater influence was exerted by the cold current 

 which found its way from the North Pole towards the equator 

 along the eastern coast of North America, thus driving the 

 warm water towards the eastern part of the North Atlantic 

 Ocean. 



The soundings of the " Blake " during the dredging season 

 of 1880 developed some striking features in the profile of the 

 slope which extends eastward from the shore along the Atlantic 

 coast, south of Cape Hatteras as far as the northern extremity 

 of Florida. The few lines run in 1880 normal to the coast, and 

 the line run parallel to the so-called axis of the Gulf Stream, 

 showed the probable existence of an immense submarine pla- 

 teau, of which the eastern edge had not been reached, or else 

 the soundings indicated a very slight slope from the shore to 

 deep water along the whole coast line south of Cape Hatteras to 

 the latitude of the Bahamas. 



Everywhere else along the Atlantic coast of the United States 



