374 GEOLOGY OF THE SECOND DISTRICT. 



Tho first district where the primary composes the surface rocks, is at Carthage, and its 

 vicinity on the eastern hmit of the county. At this place, gneiss and granite extend about 

 three miles upon the Black river, appearing in consequence of an uplift, which causes a suc- 

 cession of falls and rapids, known as the Long falls. To the north this mass extends four 

 and a half miles on the Wilna road, and also in a northeast direction, or towards the Natural 

 bridge in Lewis county. Sweeping around to the northeast, the north, and finally to the west, 

 this mass of the primary forms the whole of the northeast corner of the county, and extends 

 into St. Lawrence, where it is ten miles wide ; and as it proceeds northwest, it becomes still 

 wider in that direction. Long, narrow, and apparently insulated belts of gneiss come down 

 from the north, or from St. Lawrence county towards Evans' mills at the great bow on the 

 Indian river, extending through Antwerp to the Oswegatchie. These belts of gneiss all ter- 

 minate on the north side of this river, but their boundaries are never sufficiently defined to 

 enable me to describe them. They alternate with ridges of potsdam sandstone ; the former 

 occupying the low grounds and valleys, and the latter the ridges. 



The gneiss of Carthage presents nothing which requires a particular notice : it is deep red ; 

 feldspar predominates, and to this substance it owes its color. The gneiss, however, forms 

 low ridges which trend to the northwest, and we find a succession of them on the Wilna road. 

 The intervening spaces are low and swampy, from which there is a short abrupt rise to the 

 summit of the ridge. About one mile from Carthage towards Wilna, the gneiss passes into 

 an imperfect hypersthene rock, and also into hornblende and sienite. The gneiss of this sec- 

 tion dips to the west and northwest. 



Pursuing this mass of primary towards the Natural bridge, it still retains its distinctive 

 features, but it is associated here with primary limestone. 



In this region, though it is not elevated, we find a peculiar broken state of the surface, 

 similar to what has been before described — sharp ridges of rock alternating with swamps, a 

 condition which unfits the country for agricultural purposes. A large territory is thus consti- 

 tuted, forming a cold region, which will remain uninhabited for a long period yet to come. 



The belts of gneiss which extend south from St. Lawrence into the great bend of the Indian 

 river, and which continue west as far as Theresa falls, bear in general the same characters as 

 the gneiss of Carthage. Primary limestone is often found beneath, where an uplift has ele- 

 vated the masses forty or fifty feet. Its dip here is west or northwest ; and if we follow down 

 the Indian river from the falls, we find a succession of low bluft's, some of which are gneiss, 

 and others limestone. But six or eight miles below Theresa, in the vicinity of Muscolunge 

 lake, this rock is somewhat changed. It has now become a mixture of grey granite inti- 

 mately blended with primary limestone, the latter more frequently the inferior mass. 



This compound forms a rock quite subject to decomposition. Wherever the limestone is 

 exposed to the air, the whole mass disintegrates. Sometimes deep cavities are formed in the 

 rock, which are constantly enlarging ; and if they are formed on the banks of a river or lake, 

 and where water has access to them, the rock is gradually broken down ; and where clifls are 

 formed of this crumbling material, they are dangerous to examine. 



