8 THE WEALTH OF THE SEA 



the volume of the land above sea-level is only 23,000,- 

 000 cubic miles. If the earth were leveled off, the 

 ocean would completely cover it to a depth of about 

 1450 fathoms. 



Fossil remains of many marine animals which 

 lived millions of years ago are found in the sedi- 

 mentary rocks underlying great areas of the con- 

 tinents. This indicates that much of the earth's 

 surface that is now dry land has been under the 

 ocean at some time during the ages. A part of the 

 surface that is now submerged was once dry land, 

 but it is doubtful if any of the true ocean basins 

 have ever been above the surface of the sea. 



Temperature and Salinity 



We never think of the temperature of the ocean 

 except when we are at the sea-shore trying to decide 

 whether or not to bathe in the surf. Yet the most 

 important factor in our daily life, the weather, is 

 largely controlled by the temperature of the surface 

 water of the ocean. England is as far north as 

 southern Labrador, but it does not suffer similar 

 rigors of climate. New York has colder winters than 

 London. 



Such conditions result from ocean currents. The 

 British Isles benefit from the Gulf Stream, which 

 flows through the Straits of Florida as a river 50 

 miles wide and 350 fathoms deep, at the rate of five 

 miles an hour, in a northerly course past Cape Hat- 

 teras toward the Banks of Newfoundland, where it 

 turns more to the east, gradually widening and 

 losing speed and heat as it goes. Off Cape Hatteras 



