Coal is found in the United States in great quantities, though the abundance of wood has hitherto impeded the working of the mines to their full capability. The coal found at different localities has been classed by Professor Eaton under the following heads: first, the genuine anthracite, or glance coal, found in the transition argillite, as at Worcester in Massachusetts, and Newport in Rhode Island; also in small quantities in the north and south range of argillites along the bed and banks of the river Hudson. Second, coal destitute of bitumen, usually called anthracite, but differing greatly in its character from the anthracite found in argillite. It may be called anasphaltic coal. This is embraced in slate rock, being the lowest of the lower series of secondary rocks. This coal formation is equivalent to the great coal measures of Europe. The principal localities of this coal are in the state of Pennsylvania; as at Carbondale, Lehigh, Lackawanna, and Wilkesbarre. Third, the proper bituminous coal, as at Tioga and Lyocoming. This coal is embraced in a slate rock, which is the lowest of the series of upper secondary rocks. The fourth formation is the lignite coal, which is found in a very extensive stratum in the state of New Jersey, along the south shore of the Bay of Amboy. The anthracite of Pennsylvania is found in the Wyoming and Lackawanna valley, situated between the Blue Ridge and the Susquehanna. The coal district is chiefly occupied by mountains which run parallel to the Blue Ridge, and are fifteen hundred feet high. But little of this surface, with the exception of a few narrow valleys, invites cultivation. These mountains are mostly in a wild state, and offer a secure retreat to cougars, wolves, bears, and other animals. The rocks of the above described region are of a transition class, and present little diversity. Gray wacke slate occurs in abundance, loose on the surface and in ledges. It is sometimes based on old red sand-stone, and surmounted by unstratified rock, and aggregate of quartz, pebbles of various dimensions, with a cement principally silicious. In the Blue Ridge, in addition to the above described rock, a silicious gray wacke, resembling fine grained granular quartz, is common. It appears in some places massive, but is often slaty. Its cement is chiefly silicious; some alumine, however, is indicated in its composition.