DEPOSITION IN THE SEA 2AT 
make the beaches, because they are left while the 
currents carry off the finer clay. 
Where the coasts are made of corals, the beaches are 
built of a coral sand or conglomerate (Fig. 137), while 
the finer bits of coral mud, which are worn off by the 
waves, are borne seaward and strewn over the bottom. 
Fig. 137. 
Beach on Great Barrier Reef, Australia, composed of coral bowlders. 
On the shores of a volcanic island, the coast may be 
formed of a sand or conglomerate, composed entirely 
of the fragments ejected by eruptions. 
Therefore, the ocean deposits at the coast line are 
prevailingly coarse, but varying in texture from place 
to place. They are finest in the enclosed bays, and 
