PRELIMINARY REMARKS. 
23 
■which in time will be peopled with marine inhabitants, form¬ 
ing a complication of deposits of the most interesting character. 
§ 19. Wind Wave. The sea, as well as fresh water lakes, 
are raised into waves by winds. The movement of such waves 
will exert a constructive action upon the coast close inshore. 
The obvious effect of wind waves is to raise the sandy deposits 
in a ridge, sloping more rapidly upon the land than upon the 
sea side. This process often cuts off a bay from the sea, the 
ridge running parallel to the main shore from tw T o projecting 
points. On the land side there may be a lagoon and a marsh, 
which in due time will be filled up by aquative plants inter¬ 
mixed with soil or sand. The parallel roads and ridges travers¬ 
ing a country in the axis of its valleys, are often wind ridges, 
which mark the former shores of a lake or of an arm of the sea. 
These may be hundreds of feet above the sea level. They do 
not indicate a depression of the ocean level, but that the land 
has been raised in successive stages. Under favorable circum¬ 
stances the wind wave pushes onward the sand detritus upon 
the land. The march inland devastates the soil, and spreads 
over it barrenness and sterility. The inland sands form the 
dunes. They may be arrested by a vegetation which delights 
in an arenaceous soil, such as the beach grass (Calamagrostis 
arenaria), or some of the species of pine. 
A gentle breath of wind produces a ridged surface upon the 
sandy bottom. Waves of great strength destroy this rippled 
surface. The ripple mark will be formed in a vessel of water 
charged with earthy matter. The slightest agitation, as walk¬ 
ing across the floor, will be sufficient to arrange the sediment 
like ripple marks upon a beach. Raised beaches are often the 
joint effect of the tidal and wind wave, especially where the 
direction of the wind is constant. The transporting power of 
flood tide is not obliterated by strong contrary winds, as the 
north-east winds upon our coast and the advancing northerly 
fide wave fully show. 
A constructive action is not the uniform result of the tide 
wave; its action is often destructive. Sea bluffs are broken 
