144 
NATURE FOR ITS OWN SAKE 
The form- 
ing of 
sand-dunes. 
grind of wave and bowlder on the base of the 
cliff, until it is so eaten away that the top 
heaved by frost falls into the sea by its own 
weight. In either or any case, and however the 
weur may take place, it is slow annihilation for 
the cliff. The sea gains inch by inch. 
But the shore is not subject to all loss and no 
gain. Occasionally a great storm brings sand 
in and heaps it up along the beach. This is the 
beginning of the sand-dune—the great protector 
of the land against the sea. It must not be 
conjectured, however, that the high dunes of 
the Cape Cod shore or the low sand-banks of 
the New Jersey coast are wholly the heaped-up 
deposits of the waves. Dry sand will drift with 
the wind very much like hard ball snow, as 
anyone who has been on Sahara will testify. 
Even the tourists at Cairo, who never go be- 
yond the Mooski, will be able to say how many 
times the Sphinx has been dug out of the 
drifted sands of Egypt. Along the exposed 
shore, where the winds are always restless, 
the loose sands are kept in continual motion, 
and it is the winds that round up and build 
the hills and valleys of the sand-dunes. In 
addition to the sands brought in by the sea, the 
land breezes drift quantities of them down 
