230 ELEMENTARY GEOLOGY 
into bays, while the hills jut into the seas as head- 
lands. 
Those headlands which are exposed to ocean attack, 
are being worn back at rates varying chiefly with the 
Fia. 129. 
Sea cliff at Grand Menan, with a small beach at the base. 
force of the waves and the nature of the rock. The ma- 
terials ground off go partly out to sea and partly along 
the coast, being moved in the latter direction by the 
wind-formed and tidal currents. Coming to the mouth 
of a bay, or other indentation, these rock fragments are 
