42 



DYNAMICAL GEOLOGY. 



Resulting Forms. It is interesting to trace the 

 forms of coast-lines to their causes. If the country-rock 

 be stratified, and the strata dip toward the sea so as to 

 present their faces to the waves, then the erosion will be 

 slower and the coast-line comparatively even (Figs. 18, 

 20, a). If, on the contrary, the strata be level and the 

 waves act on the edges (Fig. 19), then the cliff will be 



FIG. 19. Section view of level strata, a and >, with edges to waves. 



undermined, overhanging tables will fall from time to 

 time, and the erosion will be rapid. Finally, if the edges 

 of vertical or inclined strata be turned toward the waves 

 (Fig. 20, b), then the coast-line will be deeply dissected, 



PIG. 20 Map view of inclined strata, dipping northward, as shown by arrow, 

 a, faces to waves ; 6, edges to sea. 



i. e., composed of alternate headlands and inlets. In these 

 inlets, the waves, gathering force as they are pressed into 

 narrower channels, beat with prodigious force. 



Again : since waves and tides act only on the shore-line 

 as high as they can reach on the one hand, and as deep as 

 they can touch bottom and form breakers on the other, it 

 is evident that they act as a horizontal saw, cutting 



