A thousand acres of land on Cape Cod were once blown away. This wind
excavation was ten feet deep. It was not an extraordinary wind, but
extraordinary land. It was made of rock ground up into fine sand by
the waves on the shore.
In all the deserts of the world the wind blows the itinerant sand on
its far journeys. If the wind is moderate it heaps the sand up into
little hills, some of them six hundred feet high, around any
obstruction, and then blows the sand up the slanting face of the hill
and over the top, where it falls out of the wind on the leeward side.
In this way the hill is always traveling. In North Carolina hills
start inland, and travel right on, burying a house or farm if it be in
the way, but resurrecting it again on the other side as the hill goes
on. Anyone may see these hills at the south end of Lake Michigan, as
he approaches Chicago, west of San Francisco, all along up the Columbia
River--the sand having come on the wings of the wind from the coast.
But to see the whole visible world on a march one needs to go to a
really large desert. The Pyramids and the Sphinx have been partly
buried, and parts of the valley of the Nile threatened, by hordes of
sand hills marching in from the desert; cities have been buried and
harbors filled up. Many of the harbors of the ancient civilizations
are mere miasmatic marshes now. This is partly in consequence of the
silt brought in by the rivers; but where the rivers do not flow in it
is because the sand blows in along the shore. Harbors are especially
endangered when their protection from the waves consists of a bank of
sand, as on Cape Cod and the Sandy Hook below the Narrows of the harbor
of New York.
How can man combat part of the continent on the move, driven by the
ceaseless powers of the air? By a humble plant or two. The movement
of the sand hills that threaten to destroy the marvelous beauty of the
grounds of the Hotel del Monte at Monterey is stopped by planting dwarf
pines. The sand dunes that prevent much of Holland from being
reconquered by the sea are protected with great care by willows, etc.,
and the coast sands of parts of eastern France have been sown with sea
pine and broom.
The tract of a thousand acres on Cape Cod had been protected by humble
beach grass. Some careless herder let the cows eat it in places, and
away went part of a township. It is now a punishable crime on Cape Cod
to destroy beach grass.