THE WORK OF THE OCEAN 



309 



vigorous wave-action, (2) prolonged transportation, and (3) a mod- 

 erate volume of sediment. 1 



Fig. 254. A portion of the Texas coast, showing the tendency of shore- 

 deposition to simplify the coast line. The deposits (the narrow necks 

 of land parallel to the coast) shut in the bays. (From chart of C. and 

 G. Surv.) 



Deposition by waves, undertow, and shore-currents. The zone 

 occupied by the shore drift in transit is the beach. Its lower margin 

 is beneath the water, a little beyond the line where the great storm- 

 waves break. Its upper margin is at the level reached by storm- 



1 Willis, Jour, of Geol., Vol. I, p. 481. 



