30 
GEOLOGY OF THE FIRST DISTRICT. 
Island is composed, are undermined and washed away by every storm. The water 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 grind¬ 
ing up of the pebbles, gravel and sand, by the action of the surf. This earthy matter is carried 
olf during the flood tide, and in part deposited in the marshes and bays, and the remainder is 
transported seaward during the ebb, and deposited in still water. After a close observation, 
I have estimated that at least one thousand tons of matter is thus transported daily from the 
north 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 fifteen miles in 
length from Montauk point westward, probably averages sixty feet in height, and is rapidly 
washing away. One thousand tons of this earth would be equal to about one square rod of 
ground, with a depth of sixty 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 proba¬ 
ble that any attentive observer would not estimate the loss of land there at less tian this 
amount. Nearly one-half the matter coming from the degradation of the land, is supposed 
to be swept coastwise in a westerly direction. 
There are many evidences that the east end of Long Island was once much larger than at 
present, and it is thought probable that it may have been connected with Block island, which 
lies in the direction of the prolongation of Long Island. From Culloden point, a reef of loose 
blocks of rock projects similar to those points on Hog island. Oak neck, &cc. -vhere they are 
known to result from the degradation of the land. Jones’ reef, northwest of Mcntauk point, is 
similar ; and Shagwam reef, a little farther west, projects three miles from tie shore. It is 
ascertained that black fish {Labrus tautogo, Mitchill) are rarely found except about a rocky 
bottom. It is also known that such a bottom of loose blocks of rock is found, wherever the 
natural soil of Long Island and the adjacent islands has been washed away by the sea. These 
facts, with the well known extensive fishing grounds for black fish around Mortauk point, and 
particularly on the south shore, and between Montauk point and Block isknd, give much 
probability to the idea that a great extent of land there has been washed away by the sea. 
Even if these evidences were deemed insufficient, the present rapid degradation of the coast 
in that vicinity, the constant transportation of matter westward upon the Great beach, and the 
extent of this beach, (more than one hundred miles long, with a breadth of one hundred to 
one thousand yards,) which is undoubtedly the result of this action, would to most minds be 
conclusive evidence of the fact. 
Sand-Dunes. 
Sand-dunes are low hills of loose sand, which have been piled up by the wind like drifting 
snow-banks ; and like them, are frequently changing their magnitude and position; so that in 
some places productive lands are buried by the moving materials, while in others they are 
uncovered by their removal. An instance was mentioned to me of land in Southampton having 
been inundated by sand, and after a lapse of about fifty years, it was uncovered by its drifting 
off. On sea-coasts, and in some places in the interior of a country, the atmosphere is often 
