270 GEOLOGY OF THE THIRD DISTRICT. 



Quaternary class. The ordinary products of alluvion were found upon the surface of the 

 greater part of the county on the west of the river, but no deposit requiring to be especially 

 mentioned. Boulders large and small, and other forms of primary rock, were found in nume- 

 rous parts, indicating a general and not a local cause of their distribution. The yellow sand 

 was in great part, if not wholly, confined to the valley of Black river. The only conside- 

 rable deposit seen of clay that was thick, was at the lower locks above the falls on the river, 

 and along the hne of the feeder ; at all other localities, the deposits appeared to be quite 

 superficial. 



The country west of Black river, through Lewis and Oneida counties, exhibits perfectly, 

 upon a smaller scale, the same erosive action which took place to the south of the Mohawk 

 valley, extending along the whole of the Helderberg range. The same causes have operated 

 aUke in both sections of the district, the difference being merely in the magnitude and direc- 

 tion of the action, and the kind of rocks. The resemblance between the general features of 

 the two sections is very striking: A deep valley traverses each in parallel directions, in 

 which clay and sand were deposited ; boulders and other rolled stones of tlie Primary system 

 are diffused over the entire surface of each, from the lowest to the highest points ; and the 

 high range in each section faces the Primary region, having a deep and broad valley at its 

 foot, with a system of lesser valleys transverse to the great one. 



6. Oswego County. 



The whole of the county presents but four rocks or groups, each occupying a well defined 

 portion of the county : its geology is therefore very simple. The oldest mass is to the north- 

 west of the county, and the newest upon the southern border. 



The first or lowest are the sandstone shales of Pulaski, which are confined to the towns of 

 Sandy-Creek, Pulaski, the northern part of Richland, the northwest corners of Albion and 

 Orwell, and the west side of Boylston. Its surface is one of denudation, the succeeding 

 rocks having at no remote period extended over it. It is the most valuable of all its masses 

 as regards soil ; the shale itself forms a good soil, and parts are highly calcareous, as at 

 Pulaski village ; and from the specimen found on Lake Erie, it also contains some good lime- 

 stone, though none was met with in this district. 



The Gret/ sandstone overlies it to the east, extending into Lewis county, and to the south, 

 covering the whole of the space north of a line which commences near the north waters of 

 Little river, and passes a little to the north of Amboy centre ; the line slightly curving to 

 Mexicoville and Butterfly post-office, and from the latter village passing on an east and west 

 line by the south side of Oswego village to the lake. This rock contains good building stone, 

 and grindstones ; the latter quarried near Salmon-river falls in the town of Orwell. 



The Red sandstone is the third rock of the county. It is coextensive with the Grey sand- 

 stone, resting upon it in its order of succession, and covering the remaining south portion of 

 the county, with the exception of a strip extending along its south border ; it is narrow at the 



