THE WORK OF THE OCEAN. 



351 



to the surface in a single plane. The bottom and roof of a sea-cave 

 usually have a pronounced inclination landward. If the chff be low, 

 the cave may be extended landward until its roof is pierced. Through 

 such an opening in the top of the cHfT the water of the incoming waves 

 may be forced in the form of spray. On the New England coast such 

 holes are sometimes known as '^spouting horns." Similar openings 

 may be made, as already pointed out, by the compression or rarefac- 

 tion of the air in the cave as the wave enters or retreats. If the roof 

 of the cave be partially destroyed, the portion which remains may 

 form an arch or hridge. Such a bridge occm-s on Santa Cruz Island, 

 California (Fig. 310). 



'*v- 





Fig. 310. — An arch developed by waves. Santa Cruz Island, Cal. (Law.) 



The 



cave. 



the '^spouting horn," the 'M^ridge,'^ the ^^pulpit-rock/' 



and other isolated islets, are all closely associated with the sea-chff in 



The wave-cut terrace. — The bottom of the sea-chff is bordered by a 

 submerged platform over which the water is shallow. This platform, 

 or at any rate its landward portion, represents the area over which the 

 water has advanced as the result of wave-cutting, and is, therefore, 

 known as the wave-cut terrace. From the method of cliff development 

 it mil be seen that the wave-cut terrace is its necessary accompani- 



