246 ELEMENTARY GEOLOGY 
blowing the sand into dunes. At the end of Florida, 
the coast is made of coral fragments; yet further, 
along the shores of the Gulf States, sandy beaches 
again prevail. 
What is seen on these shores is found along nearly 
all the ocean coasts of the world. On the exposed 
shore line, where the waves are almost continually in 
motion, rock fragments at least as coarse as sand will 
always be found. The reason for this is evident: as 
fast as the finer particles are rasped off by the waves, 
they are borne away in slowly moving currents, and 
deposited at a distance from the shore where the waters 
are quieter, or else driven into the still bays where 
they can settle. The coarse fragments cannot be thus 
transported. 
On the coast of Maine the waves are beating against 
hard rocks, and the rivers carrying little sediment into 
the sea; so here the materials are mostly derived from 
the direct attack of the waves on the coast. This 
attack takes bowlders and pebbles, and therefore the 
beaches are composed of these materials; but south of 
New York the rocks near the shore are chiefly soft 
sands and clays, from which the waves can obtain no 
large fragments. Here, also, the streams are adding 
much clay and sandy sediment to the sea. So in this 
case, even in the most exposed places, the coarsest 
fragments that can be found are sand bits, and these 
