[Frederic Shonnard & W.W. Spooner (1900)] cdiester County regions is that of Prof. I. S. Newberry, who believes,li;!i they date from the Laurentian age. The limestone beds are distributed through every geographical sec-tion of the count v. At Sim>-Sing occur marble deposits— very heavy beds which have been extensively quarried. It was, in fact, largely for the purpose of employing convict labor for the quarrying of the marble that this place was chosen as the location for the New York PHYSICAL DESCRIPTION OF THE COUNTY 15 State Penitentiary. The Sing Sing marble, however, although an admirable building stone for many purposes, is of comparatively coarse and inferior quality, becoming stained in the course of time by the action of the sea air on account of the presence of grains of iron pyrites. Marble is also quarried at Tuckahoe. Abundant indications are afforded of extensive and radical glacial action. " Croton Poiut, on the Hudson, and other places in the county, show evidences of glacial moraines. Deep stria? and lighter scratches still remain upon many exposed rock surfaces, and others have been smoothly polished." A prominent feature is the presence in greal profusion of large granite bowlders, undoubtedly transported by glaciers from Massachusetts and New Hampshire, with an inter-rm* EARLY NAVIGATION IN THE HIGHLANDS