The geology of Long Island has always been regarded as a particularly interesting theme for those concerned in the study of such matters, since the examination of its phases brings into view so many and such various points of speculative interest. Prime in his "History of Long Island"[3] remarks that "when we consider the retired situation of Long Island, and how little it has excited the notice of travelers, it is not surprising that its geological character as well as other peculiarities should have remained so long unexplored. Until quite recently very few scientific men have even deigned to give it a passing notice, though the assertion may be safely hazarded that scarcely any other tract of land of equal extent on the American Continent furnishes more abundant room for the _imagination_ of geologists to play upon, or that imposes a stronger necessity for _conjecturing_ the operation of some tremendous agency, which in its freaks had invaded the domains of both the land and the ocean, and after completing its sport had silently retired without leaving a track to determine its origin or identify its form." The geologist of the present day does not seem to regard the field as one calling in the same degree for the exercise of the imagination, though the more definite knowledge acquired and made familiar since the time of the publication just quoted has in one sense vastly extended the opportunity for speculation. Certainly it no longer can be said that scientific men have neglected the investigation of the subject. Commenting on the investigations of Dr. Dwight, Prime says:-- "From all these considerations, the inference has been regarded as legitimate that Long Island was once through its whole extent attached to the main; and some powerful agency, the form of which is now left entirely to conjecture, forced the separation which is now marked by the intervening Sound. One of the most plausible suppositions is that the separation has been effected by some resistless torrent of water, which, under peculiar circumstances that it is impossible now to determine, has swept out the intervening land, and left its channel to be occupied by the waters of the ocean." Thus vaguely were the early speculations set forth. With a well developed glacial theory to aid him the modern geologist is able to present a fairly circumstantial picture of probable conditions in the past. We now know with reasonable certainty that Brooklyn rests on soil that is a monument to a vast force quite different from any that were included in the hesitating speculations of the early writers.