BATTLE OF SEA AND LAND 171 



This may seem strange at first, for we com- 

 monly think of the seashore as at a constant 

 level, but in reality the elevation of the coasts 

 is ever changing. In one place it may rise 

 slowly through many centuries and in another 

 it may slowly sink. At other times a portion 

 of the coast may rise in a short time for many 

 feet, and on the other hand a single earth- 

 quake or volcanic eruption may cause a por- 

 tion of the coast to sink far beneath the level 

 of the sea. 



Even large islands at times sink suddenly 

 beneath the sea without warning and many 

 people believe that the wonderful continent of 

 Atlantis really existed in ancient times and 

 was submerged by some great cataclysm of 

 this sort. We have no proof of this, but we 

 do know that islands and large portions of 

 continents have disappeared in this way. 

 Some of these catastrophes took place ages 

 ago, before man inhabited the earth, while 

 others have occurred within comparatively re- 

 cent times and even within the memory of liv- 

 ing men. 



Off the coast of Yucatan is a little island 



