78 
[Assembly 
which is situated on the main Island, was originally three islands, 
now connected with each other and with the main Island, by 
beaches and marshes of alluvial formation.* Those long points 
of alluvion called sand spits, projecting from the land, in the line 
of the eddy currents, and formed by them, are very common, and 
they are, in fact, the unfinished beaches which will eventually ob^- 
struct the outlet of harbors and bays, and connect islands with 
each other. An interesting alluvial formation is now in progress 
on the north and north-west sides of Loyd's neck, in Huntington, 
and formed entirely by the deposite of the coarse detrital matter, 
swept along by the current from the destruction of the high cliffs 
in the vicinity. This deposite is about one quarter of a mile broad, 
partly marsh and salt pond, protected by a high bank of shingle, 
piled up and continued westward, so that the present outlet of 
the pond is half a mile further west than it was within a recent 
time; the shingle having been continually 'swept westward, while 
the flux and reflux of the tide through the narrow channel, keeps 
its outlet open. 
The ponds and small bays, on the south side of Long Island, in 
the townships of Southampton and Easthampton, frequently have 
their outlets closed by beaches, formed by the detrital matter swept 
coastwise by the tidal currents and the waves. The long sandy 
islands on th^ south coast of Long Island, which protect it from 
the heavy waves of the Atlantic, are doubtless formed by the same 
cause. Long beach is a sand-spit extending from Ben's Point, near 
Oyster Pond Point, westward, four and one-fourth miles, and has 
been formed by the detritus being swept coastwise and deposited in 
the eddy currents. This beach gives safety to Oyster Pond's har- 
bor, by serving as a natural breakwater. (Vide map of Oyster 
Pond Point.) Two sand-spits were observed in Cold Spring har- 
bor, resulting from causes similar to those above detailed. 
* The effects of alluvial action can be distinctly seen on the map of Oyster Pond Point, 
This map shows where two of the islands which were once separated from the E. end of 
the N. branch of Long Island, have been connected by the beach E, and the sand-spit C, 
enclosing a large pond F, with an outlet only wide enough for a mill sluice. A tide 
mill is constructed at this outlet. Mr. W. H. Sidell, a highly promising and accomplish- 
ed civil engineer, has made a minute topographical map of the country from River Head 
to Oyster Pond Point, in the discharge of his duties as engineer of the LoQg Island rail- 
road; and I am indebted to his kindness for being able to illustiate graphically the trans- 
porting power of the waves and of tidal currents, and the effects produced by the deposite 
of sand and shingle forming long spits and beaches. 
