THE FORMS CARVED AND MOLDED BY WAVES 235 



are not rounded, but retain 

 their sharp angles. 



The cut rock terrace. 

 When waves first begin their 

 attack upon a steep, rocky 

 shore, the lower limit of the 

 action is near the wave base. 

 The action at this depth is, 



however, less efficient, and as FIG. 253. The Marble Islands, stacks in 



the recession of the cliff is One Lake Buenos Aires, southern Andes 

 f . , i < -1 (after F. P. Moreno). 



of the most rapid of erosional 



processes, the rock floor outside the receding cliff comes to slope 



gradually downward from the cliff to a maximum depth at the 



FIG. 254. Squared stacks which reveal the position of the joint planes which have 

 controlled in the process of carving by the waves. Pt. Buchon, California 

 (after a photograph by Fairbanks). 



edge of the terrace, approximately equal to wave base (Fig. 255) . 

 This cut terrace is extended seaward or lakeward, ^s the case may 

 be, in a built terrace constructed from a portion of the rock de*bris 

 acquired from the cliff. 



