COKA.L, BY MWlTA L'NDERHlLL 



GO 



into the water, and then is level for a ways, and then slopes suddenly and 

 steeply again. It is where the land is about to slope the second time that 

 the coral polyp builds. The coral polyp will build until he reaches the sur- 

 face, and so forms a coral reef five miles or more from the main land with 

 a lagoon between. There is a barrier reef off the southern coast of Flor- 

 ida, from the islands of Tortugas to Cape Florida. This is one hundred and 

 seventy-five miles long, and is the only coral reef in the United States. 



Fig. 32^ 



Atoll, by Evelyn Pascal. 



There is another one off the north-east coast of Australia, which is the 

 largest and greatest one in the world. It is a thousand miles long and high- 

 er than Bunker Hill Monument, built in the midst of a rough sea, where no 

 work of man could stand the high, strong, ruinous waves. The Egyptian 

 pyramids and the great wall of China seem like playthings beside it. 



There is another kind of reef still, the fringing reef. It is formed where 

 the land gradually slopes under the water. The little polyp builds on this 

 slope at a place one hundred and fifty feet from the surface of the water. 

 It builds up against the land and reaches the surface, so forming a fringe 

 of coral on the land. The only fringing reef of much importance is the Mo- 

 lasses Reef off the island of Inagua, near Cuba. 



The coral polyp has a good influence on commerce, as the lagoons of 

 the atolls form safe and excellent harbors for ships. It is also a hinderance 

 as many vessels run upon the coral reefs and are wrecked. 



The Bahamas, which were made by the little coral polyp, have turned 

 the Gulf Stream from its natural course, straight across the Atlantic Ocean, 

 up along our Atlantic coast, thus making the climate of the Middle Atlantic 

 and New England States a great deal warmer. 



