What is the effect of waves upon the coast, when it consists of unsolidified materials?
Describe their effect upon rocky coasts.
How is the encroachment upon such coasts shown?
Fig. 73.
What is the effect of waves of less power?
How are marine currents produced?
How are they increased by the evaporation of the torrid zone?
What are the most important marine currents?
Which class of currents have the greater depth?