250 GEOLOGICAL SURVEY OF NEW JERSEY. 



quality. This litter and mud are abundant and available to all 

 those who have enterprise and energy enough to utilize them. 

 The mainland and marine marshes are protected from the 

 action of the ocean waves by a line of barrier beaches or sea 

 islands. These beaches, on which are located many famous 

 resorts, are separated from one another by inlets through which 

 the tide sweeps swiftly. Strictly speaking, a beach is that part 

 of a shore between high and low water, but in New Jersey the 

 term is applied to what are really sea-islands. These islands 

 consist of a fine white sand which in places is mobile. When 

 the tide falls, the sand of the beach proper, dried by the sun 

 and wind, is blown either inland or into the ocean. The pre- 

 vailing winds blow toward the sea, and the sand as it dries flies 

 back into the water to be whirled again on the beach by the 

 waves. If the wind continues for some time from the sea, sand- 

 hills are formed. Any small obstacle sufficient to diminish the 

 energy of the wind may cause the commencement of a dune. 

 As soon as a little hill is formed, it is easy to see how it may 

 continue to form while the conditions remain the same. Soon 

 a strong west wind, however, may hurl it back into the sea, or 

 an eastern gale fling it inland on the marshes. And so it goes, 

 forming and re-forming, changing in fact with every caprice of 

 the wind, gentle and almost unnoticeable during a light sea- 

 breeze, but a stinging, blinding sand-blast in times of gale. In 

 case of an obstruction, which interferes with the action of 

 the wind, a dune forms equal in height to the obstacle. A 

 great deal of the land on these islands is now occupied by 

 resorts ; it is all in fact owned by private parties, and is in 

 places extremely valuable. But here and there are tracts of 

 wild, shifting dunes. At Avalon there is a huge dune, caused 

 by a dense forest which is being slowly but surely engulfed. 

 The dune begins just above high-water mark, and then extends 

 inland, gradually increasing in height until its summit is even 

 with the foliage of the trees. It is a peculiar scene from the 

 top of this dune ; on the land side there is a dense mass of dark 

 green foliage, beyond which there is the broad expanse of green 

 salt marshes with their bays and thoroughfares.* On the ocean 

 side, sloping to the breakers, there is a huge mass of fine sea- 



A waterway from one bay to another is called a " thoroughfare " along the Jersey coast. 



