There are many evidences in support of the theory that since the completion of the great glacier's work the surface of Long Island has subsided considerably. A recent writer[4] on the geology of Long Island says: "The shore at the west end of the island has also undergone decided changes--even within the memory of persons now living. Personal witnesses have testified that about the first of this century Coney Island was composed of high and extensive sand hills, which have since been flattened down to a low beach, sometimes covered by the tides. About the same time salt meadow-grass was annually cut on a part of the beach now far out into the ocean. We are also informed that cedar-trees were cut for fence-posts, and other timber for firewood, about 150 years ago, on land which is now submerged by the ocean a mile and a half or two miles from the shore. There was also a house standing upon what was known as Pine Island, the site of which is now beneath the breakers, at a considerable distance from the present shore." Within the range of Kings County a stratum of salt meadow has been found at a depth of one hundred and twenty feet, and at other points within the county shells have been found fifty and sixty feet below the surface. What is generally called the "back-bone of Long Island" is a ridge of low hills beginning at the western end within the limits of Kings County and running almost the whole length of the Island. Of the boulders or erratic blocks found on the Island in this central range of hills and between them and the north shore, Mr. Bayles writes:--