LEWIS COUNTY. 265 



insulated patches or outliers which appear at the extreme north end of the county, resting 

 upon the rocks of the Primary system. 



Black river is an important feature of the county, being the chief outlet of its drainage, and 

 forming the boundary between the well settled parts and that which is but thinly inhabited ; 

 its primary portion being, with some exceptions, like that of the district, yet a wilderness. 

 The immediate valley of the Black river consists of the primary rocks, but thev rarely extend 

 more than a few hundred yards to the west of the river in any part of its course in the county. 



The rocks which form the west side of the county, are the Black river hmestone, Trenton 

 limestone, Utica slate, Frankfort slate, sandstone shale of Pulaski, and the grey sandstone of 

 Oswego. These rocks are arranged with great regularity. They form a series extending 

 through the county, ranging nearly parallel with the river, rising one above the other in regular 

 succession, the most ancient forming the margin of the river on the east, and the newest on 

 the west. At the northern extremity of the county they all curve westwardly, their range in 

 the county being northwest. The rocks which appear as outliers or insulated masses upon 

 the primary, are the Potsdam sandstone and the fucoidal layers : the former was seen only 

 near Lewisburg furnace and Harrisville, and the latter between the furnace and the Natural 

 bridge. 



The opposite sides of the river form the strongest contrast imaginable as to rocks, soil, 

 vegetation and population. The surface of the east side consists, with few exceptions, of an 

 almost unbroken range of forest, spread upon an uneven surface, the result of materials or 

 masses first disturbed, and subsequently water-worn ; no part of its surface in Lewis county 

 presenting elevations of consequence, except near the southern part, where it joins to Oneida, 

 and forms low mountain ridges. The western side of the river, on the contrary, is well settled, 

 and exhibits those steps or terraces common to horizontal rocks or undisturbed mechanical 

 deposits ; presenting an almost unbroken outline, the lowest mass of which, the Black river 

 limestone, rises and forms the west side of the river valley, either by the side or upon the 

 primary, the junction no where perceived, and presents a cliff or mural precipice extending 

 through the county. In no part of the whole of the division east of Black river, could I find 

 or hear of a single rock that was not comprised in the Primary system, with the exceptions 

 already mentioned ; making it certain that the county is naturally divided, as before said, into 

 two geological systems ; the eastern formed of the rocks of the Primary, and the western of 

 those of the New- York system. 



This county admirably illustrates the connection which exists between rock, soil and popula- 

 tion ; the limestone and slate lands being well settled, and the primary comparatively unsettled. 

 The difference is independent of temperature ; for the whole of the north portion of Lewis, 

 and that part which for miles borders upon the river, lies at a lower level than the land to the 

 west ; the former being unsettled, and the latter a well settled country. 



From all observations made, the primary presents but few rocks, consisting chiefly of granite, 

 and that peculiar kind of gneiss common to the west primary region of New- York. This 

 kind of gneiss contains but little mica, and shows little tendency to decomposition, disintegra- 



Geol. 3d Dist. 34 



