TRENTON LIMESTONE. 51 



every where else, and from finding it on the west side of the Noses, and in the same position 

 on the west side of Little-Falls to the north of the river. 



The Trenton limestone has been uncovered to a considerable extent along the southwestern 

 boundary of the primary. In Herkimer county, it covers a large portion of Norway, all but 

 a fraction of Russia, and that part of Ohio which borders at the southwest on the two former 

 towns. In Oneida county, it forms a continuous surface with Herkimer, and extends along 

 the primary, averaging about three miles in breadth, and passing into Lewis county. Where 

 it joins to Herkimer, its breadth increases, extending up to Stittsville and Holland patent, and 

 into the valley of Beaver meadow as far as the mouth of Wells' brook, where it disappears 

 under the Utica slate, but soon reappears on the Mohawk. In Lewis county, it ranges nearly 

 parallel with Black river, curving west in conformity to all the exposed rocks of that section. 

 It forms a continuous mass in the three counties ; that is to say, in all its course there, its 

 surface, except on the south and west sides, is not covered by any other products than those 

 of soil and alluvion. 



Where the rock is thin, the dark color prevails ; where it is thick, the lower parts retain 

 the same kind of dark and thin layers, but the upper are often thick and of a light color. 

 Layers of the latter kind occur in the valley at Holland patent and Stittsville, on the waters 

 of Beaver meadow, at Trenton falls, along Cincinnati creek, and in numerous points where 

 the Trenton limestone is exposed through Oneida and Lewis counties, but none were noticed 

 so pure and solid as those of the first named places. 



Where the road which leads to Prospect leaves the one from Trenton village to Boonville, 

 there is quite a novel exhibition, the water of the creek appearing in streams by the joints 

 and other openings in the limestone which forms the bottom of the Cincinnati creek ; above 

 the bridge, the water is seen entering the creek ; higher up, the whole stream is deserted, 

 presenting a rock surface, under which, and by the joints of the rock, the water courses by its 

 subterranean route to where it reappears near the bridge. 



From the facts here presented, the origin of the Natural bridge in Virginia is readily under- 

 stood. The bridge crosses a narrow deep limestone valley, like that of Trenton falls ; the 

 bridge being a part of the original rock which filled the valley, all the other parts having been 

 removed by the same cause now acting in Cincinnati creek, and in the same manner. The 

 rock there belongs to the same system, and is nearly of the same age with the trenton. The 

 latter rock shows from one to three vertical joints ; but in all rocks, the number varies in a 

 given space : as a general rule, they are 'fewer where the layers are thickest. All, therefore, 

 that it is necessary to conceive, in order that a bridge of the kind should be formed, is that 

 water should flow as at the Cincinnati creek ; that a part connected with the sides, and near 

 the surface as in Virginia, should be more solid than the other parts where the water flows ; 

 and finally, that all should be removed but the solid portion, leaving an excavation like that of 

 Trenton falls. 



The grey limestone is quarried at Cincinnati creek as a marble, and burnt also for lime ; 

 it is also quarried in many places in Holland patent, Beaver meadow, &c. 



The vertical joints in the Trenton limestone are generally two in number. In Martinsburgh, 



