THE LONG ISLAND COAST. 435 



in recent time, in consequence of which its bluffs have been under- 

 rained by waves, and the lowlands submerged. Immense bowlders 

 lie upon some portions of the shores, which indicate the sites of recent 

 banks and headlands. 



The wearing away of an exposed coast, like that of the east end 

 of Long Island, suggests a subsidence, by which it is continually 

 being: brought under dominion of the waves. Did no such change 

 occur, the abrasion would be retarded, or might finally cease, unless, 

 indeed, the falling material be removed by a coastwise drift of the 

 .water. The tendency of wave-motion is to throw upon shore the 

 waste of the cliffs, thus raising a breakwater on which the waves 

 expend their force. But, where low grounds along the ocean-margin 

 become permanently overflowed, the proof is conclusive that a change 

 of relative level has taken place. There has been no abrasion by 

 waves, but silently and imperceptibly the tides have advanced upon 

 the uplands. 



Around the shores of Long Island are large areas of recent forest, 

 swamp, and meadow, with remains of their peculiar forms of vegeta- 

 tion in many cases undecayed, covered by water to depths of from one 

 to sixteen or more feet. Some facts illustrating this were presented 

 to the Natural History Section of the Long Island Historical Society, 

 in May, 1868, a synopsis of which was published in the American 

 Naturalist for August of that year. A few of these, with others of 

 importance since discovered, are offered in this paper: 



The movement under consideration is by no means a local one, 

 but occurs along the Atlantic border from Labrador to the Capes of 

 Delaware, and in a lesser degree to Florida. Prof. G. H. Cook, in his 

 admirable " Report on the Geology of New Jersey," cites many in- 

 stances along the coast of that State where swamps of cedar and 

 other forms of vegetation are now submerged, or covered with salt 

 meadow. 



On the south side of Long Island are about 40,000 acres of salt 

 marsh and meadow. Their vast stretches of level surface, fringed by 

 the Great South Bay and the beach on the one side, and by uplands 

 on the other, present a scene of rare and surpassing beauty. The 

 meadow rests upon a floor of gravel and sand. It varies in thickness 

 from a few inches at the uplands to eight or ten feet near the beach, 

 and is filled with the roots of grasses throughout. It has been formed 

 by growth and accumulation at the surface, for the meadow-grasses 

 thrive only at or near high-tide level where rainfall and sunshine can 

 reach them. The increase of the meadow in thickness has, therefore, 

 just kept pace with the deepening of the water, or in other words, 

 with the sinking of the coast. 



Beneath the meadows remains of swamp and forest are found. 

 These are fast rooted, and often six feet beneath the surface. At 

 Islip a great number of stumps are found in the salt meadow of Wil- 



