292. ELEMENTARY GEOLOGY 
from the place where they were formed. So the 
surface of the sea is constantly disturbed, and even 
in calm weather the water heaves with the passage of 
swells which have originated far away. 
In the open ocean these waves do almost no geologi- 
cal work. The surface rises and falls, and any floating 
Fig. 123. 
The limestone of the Bermuda coast, roughened by solvent action of the 
sea water. 
object merely moves up and down, while the wave 
passes on. There is a slight forward and backward 
motion in the wave, because the water particles do 
not rise and fall vertically, but pass through an 
elliptical path. There are, therefore, two important 
movements in the wave, one of the water particles 
