CLINTON COUNTY. 319 



wliich intervenes, never contains it. Orthoceratites are sometimes large and abundant. Very 

 few, if any, of the Trenton fossils are ever found in it ; hence it seems to be a mass more 

 nearly allied to the limestones below, than to those above. 



Quarries of this marble might be opened at or near the landing at Chazy. The texture of 

 this mass, if any thing, is finer liian that upon the island, and might probably be worked to 

 equal profit and advantage. 



Trenton Limestone. 



This rock, though well characterized in Clinton, abounds more in shaly layers than usual. 

 It commences (taking the locality at Chazy as the tj'pe for description) with alternating 

 layers of black limestone from two to four inches thick, and black shivery slate in almost the 

 same proportion. The layers of limestone are somewhat thicker in a higher position ; but, in 

 general, such is the character of the whole mass, w'hich is about four hundred feet thick at 

 Chazy. Varying but little from the above, I found the same rock at and in the vicinity of 

 Plattsburgh. The calcareous part is fine grained, and as beautiful as any of the black marbles, 

 but it is very tough and difficult to break. 



In all respects excepting the amount of shale, the trenton hmestone of Clinton maintains 

 a uniformity of character, and in all respects agrees with the same rock at Trenton and 

 Glen's-FaUs. The position it occupies geographically, is near the lake shore. At Chazy, it is 

 farther west than at any other place from Whitehall to Champlain, and here it is only four 

 miles. The probability is, that Lake Champlain now occupies the space which was once 

 filled with this mass ; and that, being slaty and subject to disintegration, this rock has in a 

 great measure been broken down and decomposed. On either side it remains, and also in the 

 islands it forms the surface rock ; but the great mass, for one hundred and twenty miles in 

 length, has disappeared. 



At Plattsburgh upon the shore of the lake, and at Cumberland head and the shores down 

 to Rouse's point, the trenton limestone is the surface rock. The upper part of the mass at 

 Isle La Motte is also the same ; and we find it overlying the black marble, so justly cele- 

 brated for mantel and other ornamental purposes. 



The fossils, wherever they occur, are similar to those at Trenton, as the Isotelus gigas, 

 Calymene senaria, Orthis alternata, etc. ; each of which abound at Plattsburgh and Chazy, 

 Cumberland head. Grand Isle and Isle La Motte. For figures, see Jefferson county. 



The extent of this rock may be learned from the preceding localities, and the remarks already 

 made. 



Utica Slate. 



This rock forms only a narrow belt in Clinton, and is confined wholly to the immediate vi- 

 cinity of the lake : its exposures, too, are quite limited and unimportant. The only position in 

 which it can be examined, is three or four miles southeast of Chazy, towards the lake. It 

 presents nothing of sufficient interest to require even a passing notice. On Grand Isle, or 



