ATLANTIC OCEAN 



462 



ATLANTIC OCEAN 



from 14,000 to 15,000 feet, and the western from 

 13,000 to 16,800. North of the Azores Islands 

 the bottom of the ocean gradually rises and 

 forms a plateau whose length extends from the 

 Hebrides to Newfoundland. This is sometimes 

 known as the telegraph plateau, because the 

 Atlantic Cable is laid on it. Along this plateau 

 and over the ridge separating the valleys the 

 ocean has a depth of 9,000 to 10,000 feet. The 

 greatest depth, 27,360 feet, is north of Porto 

 Rico; east of Newfoundland a depth of 20,000 

 feet has been found, and in the South Atlantic 

 there are depths of 20,000 to 24,000 feet. These 

 are not as great as some depths in the Pacific 

 Ocean, where telegraph cables have been laid 

 six miles below the surface (see CABLE, SUB- 

 MARINE). 



Shore Lines and Coast Waters. The eastern 

 shore line has a length of 32,000 miles; the 

 western, 55,000 miles. The coasts of Europe 

 and North America are very irregular, but 

 those of Africa and South America contain few 



EXTENT OF ATLANTIC OCEAN 



indentations. The coast waters on the east are 

 the North Sea, Baltic Sea, Bay of Biscay and 

 the Mediterranean and Black seas, the latter 

 over 2,500 miles inland. On the west they 

 include Hudson Bay, the Gulf of Saint Law- 

 rence, Gulf of Mexico and Caribbean Sea. The 

 most important islands in the North Atlantic 

 are the British Isles, the Canaries, Iceland, 

 Greenland, Newfoundland, the West Indies, 

 the Azores and Cape Verde Islands. The 

 islands of the South Atlantic are comparatively 

 unimportant. 



Temperature. The temperature at the sur- 

 face varies from about 80 F. in the tropical 



Outline and Questions on 

 the Atlantic Ocean 



I. Location nud Sice 



( 1 ) Boundaries 



(2) Length, 13,000 miles, including 



Antarctic Ocean 



(3) Average width, 3,000 miles 



(4) Greatest width, 5,000 miles 



(5) Area, including coast waters, 41,- 



000,000 square miles 



II. Shore Line and Const Waters 



( 1 ) Coasts of northern part irregular 



(2) Length of shore 



(a) Eastern, 32,000 



(b) Western, 55,000 



(3) Coast waters 



(4) Islands 



III. Ocean Bed 



( 1 ) Two parallel valleys 



(2) Telegraph plateau 



(3) Varying depths 



IV. Temperature and Currents 



( 1 ) Temperature at surface 



(2) Temperature at bottom 



(3) Gulf Stream 



(4) Labrador Current 



(5) South Atlantic currents 



V. Life 



(1) Source of food supply 

 (a) Fisheries 



(2) Smaller forms 



Questions 



If the highest mountain of North 

 America were placed at the deepest 

 point in the Atlantic Ocean, would its 

 top show above the water? 



How does the ocean compare with 

 other great bodies of water as regards 

 regularity of outline? 



Does the temperature of the ocean 

 vary according to depth as the tem- 

 perature of air varies according to 

 altitude? 



How large a proportion of the land 

 surface of the globe could the Atlantic 

 Ocean contain? 



Why is the western coast of Europe 

 warmer than the eastern coast of North 

 America in the same latitude? 



From what is the name of this ocean 

 derived? 



What Is the "telegraph plateau," and 

 why is it so named? 



About how many square miles of 

 water surface are there on the globe? 



How does the Labrador Current work 

 damage to navigation? 



