132 
[Assembly 
the drift sand settles among its leaves and partly buries it, and the pro- 
cess is renewed for years, until a sand hill is formed. On the contrary, 
where there is nothing to bind the sand together, or shelter it from the 
wind, it drifts away, leaving deep hollows. Drifted snow banks afford 
an apt illustration of the sand dunes of the south beach of Long Island, 
and in a high wind we can there realize, in a small degree, the sand 
storms of the African and Arabian deserts. 
It has been remarked that some of the islands and spits of the Great 
South Beach, are continually receiving accessions on the west end. 
Long bars form in the prolongation of the beaches, so that each succes- 
sively overlaps the other, the entrance being from S. W. to N. E. 
They project in echellon, from the E. N. E. to W. S. W, Many of 
these shoals, formed at some distance from the land, are gradually driven 
landwards by the surf, and make new additions to it. 
During the investigation of the various alluvial causes now in action 
on this coast, we easily trace the origin of this great sand beach of more 
than one huiidred miles in length.* 
The encroachments of the sea on the east end of Long Island, were 
discussed in my first annual report. Vast masses of the cliffs of loam, 
sand, gravel, and loose rocks, of which Long Island is composed, are 
undermined and washed away by every storm. The w^ater on the ocean 
coast, to some distance from the shore, is almost always found to have 
more or less earthy matter in suspension, much of which, except during 
storms, is derived from the grinding up of the pebbles, gravel and sand 
by the action of the surf. This earthy matter is carried off during the 
flood tide, and in part deposited in the marshes and bays, and the re- 
mainder is transported seaward during the ebb, and deposited in still wa- 
ter. After a close observation, I have estimated that at least 1,000 
tons of matter is thus transported daily from the coast of Long Island, 
and probably that quantity on an average is daily removed from the south 
coast, between Montauk Point and Nepeague beach. This shore of 15 
miles in length, probably averages 60 feet in height, and is rapidly 
washing away. 1,000 tons of this earth would be equal to about one 
square rod of ground, with a depth of 60 feet. Allowing this estimate 
to be within the proper limits, more than two acres would be removed 
annually from this portion of the coast. It is probable that any atten- 
* In Europe there is no deposit of a similar character to compare with it in extent. It is 
lioped that the topographical maps of Long Island may be completed and published by 
the Government, in season to make use of them for illustrating, in detail, the minute geo- 
logy of this interesting region. Our county maps are not sufficiently accurate for this pur- 
pose. 
