14 Practical Farming 



Then occurred an elevation of that part of the sea 

 bottom where they had been formed. The great white 

 chalk cliffs of England, for example, and the white num- 

 mulite limestone of the lower Mississippi valley, arose 

 from under the sea. Such processes still continue. In 

 the waters of the North Atlantic Ocean myriads of minute 

 animals exist which form a shell of lime carbonate, and 

 their empty shells are forever faUing in showers to the sea 

 bottom. The whole of the telegraphic plateau, as it is 

 called, between Newfoimdland and Ireland, has a bottom 

 composed of a deep ooze known to scientists as the Glober- 

 gerina ooze, composed of the shells of these minute ani- 

 mals, the flint spicules of sponges and the skeletons of 

 microscopic diatoms. Dredge up some of this mud from 

 the ocean bottom and dry it and you can write with it on 

 a blackboard just as with common chalk. 



All the while the forces of the great sea waves are at 

 work in the formation of soil. They eat into the hard 

 chffs and dash up at another place the fine particles of 

 sand. At low tide the sand dries and the winds blow it 

 into the great sand dunes that line the coasts covering the 

 marshy land behind them. A forest grows there and 

 after a while other sand dunes are formed, drift inward 

 and bury the forest. Thus a greater elevation of land is 

 made while the sea gradually eats landward and at im- 

 portant points a sea wall becomes necessary to protect 

 human interests. No sooner have the forces of nature 

 elevated a portion of land above the sea than the waves 

 put in their work of breaking it down. 



But the sea is the great agent of another work in the for- 

 mation of soil. In the more shallow waters along the coast, 



