SAND DUNES AND SALT MARSHES 



peared in places, and the sand collected about 

 them and formed the beginning of dunes. 



Later, owing to some change in the currents 

 along the shore, the waves demolished their 

 own handiwork, and in 1908 veritable sub- 

 fossils, the shells of the common clam, began 

 to appear on the outside beach, standing in 

 place with their empty valves pointing up- 

 ward as in life. 



While clumps of beach grass are often re- 

 sponsible for the birth of a dune as just de- 

 scribed, any obstacle or irregularity, in whose 

 lee the heavier grains of sand settle, may also 

 start a dune on its progress. However 

 started, their forms are many and various, 

 yet, as they are all dependent on the winds, 

 they are shaped by the strongest or dominant 

 ones, and these are the winds which blow from 

 the northwest, north and northeast, during 

 the winter months. Certain secondary or 

 transient modifications are due to other 

 winds, particularly to the prevailing south- 

 west breezes of summer, but a visit to the 

 dunes in a snow-spitting northeaster of win- 

 ter gives one an idea of aeolian power not 

 often realized in the gentler summer season. 



Smiling skies, gentle balmy breezes, flowers 

 14 



