ESSEX COUNTY. 279 



The Triarthus bcckii is one of the most common fossils of this rock, a figure of which is 

 annexed (No. 1), together with Trocholites ammonius (No. 3), and Graptohtcs dentatus (No. 

 2). Individuals of the first named species do not, however, often appear crowded together, 



74. 



but generally only two or three individuals are found near each other, and neither does every 

 locality furnish specimens of it. 



This mass never abounds in fossils of any kind : they arc more numerous near its junction 

 with the Loraine shales ; and it is possible, that inasmuch as this is more exposed to denuding 

 agents, this portion may be very frequently removed. Near the trenton limestone, fossils are 

 very scarce ; but proceeding upwards they increase, and in some localities, as in iheLorain e 

 gorges, they become quite common near the shales which succeed. 



New-York System in Vermont. 



Before leaving the rocks of Essex county, I deem it necessary' to notice their appearance 

 on the east side of Lake Champlain. This sheet of water occupies a space intervening be- 

 tween the broken edges of the several masses which line the shore upon each side, and it 

 seems to have been made partly by a fracture through them, extending nearly due north its 

 whole length. The dip of the rocks favors this hypothesis, for they arc thrown in many in- 

 stances each way, or from the lake : the rocks upon the west side, dip verj' frequently west, 

 or northwest ; and those on the opposite side, to the east. These rocks occupy by far a much 

 greater area upon the east than upon the west side, with the exception, perhaps, of the pots- 

 dam sandstone, which appears in great force only on this side at the head of the lake, where 

 it forms a mountain at Whitehall ; but it is particularly found extending for several miles down 

 the lake, in high mural precipices. It does not appear below Kenyon's landing, a distance 

 of about twelve miles from the head of the lake. 



Opposite the county of Essex, a very perfect series of the Champlain group is exposed at 

 different points. But the most useful and interesting places for examination are those which 

 are opposite Port Henry and the village of Essex ; the first is Addison, and the second, 

 Charlotte. 



The rock upon the lake shore in the former place, is the trenton limestone. Seven miles 

 to the east, Snake mountain rises boldly from the midst of a plain. At the base of this moun- 



