Review of the New York Geological Reports. 375 



might not these fossils, originally perhaps of a fleshy nature, 

 have been transformed into carbon, somewhat in the same way 

 that calcareous bodies have become siliceous during the process 

 of petrifaction ? Or might not, by the action of some chemical 

 affinity, the less stable elements of the Polyparia have been re- 

 moved and the carbon alone left ? 

 Prof. Emmons gives five figures of fossils of the Utica slate 



Numl 



Nuculitcs 



la , Lingula 



recti lateralis. Besides these there occur in it A. Trocholites. 



According to Mr. Vanuxem the following fossils are common 

 to the Utica slate and Trenton limestone; Orthis striatula, 

 Strophomena alternata, Lingula ovalis, Favosites Lycoperdon, 



Isotelus gigas. Calymene senaria. 



The range of the Utica slate is more extensive than that of 

 the underlying Trenton and Black River limestone, since it is 

 not only coextensive with these formations on the Mohawk and 

 Black River, but extends further east, and forms, by Mr. Mather's 

 account, a large portion of the slates of the Hudson valley. In- 

 deed there are red and brown slates on the east side of the Hud- 

 son, which he refers to this formation, that range from Canada 

 through Vermont, New York and New Jersey across Virginia. 



Near Fort Plain, Utica, Hudson, the deep gorges at Rodman 

 and Loraine, and Glen's Falls, are the best localities for the ex- 

 amination of the Utica slate. 



In the valley of the Mohawk and Black rivers, the Utica 

 slate forms the surface rock ; through it, by uplifts, the inferior 



masses protrude. 

 Some of the best grass and dairy lands of the state, have been 



derived from the degradation of these slates. 



North of Little Falls, thin layers of fibrous sulphate of stron- 

 tian have been observed by Vanuxem, running parallel with the 

 slate. Some small seams of lead ore traverse the Utica slate, but 

 no regular veins exist. Various unsuccessful explorations have 

 been made in this formation in the valley of the Hudson for coal 

 and considerable sums have been expended in consequence of 

 having found thin layers and small lumps of anthracite in it. Of 

 course all such attempts must inevitably result in disappointment 

 and loss, for reasons previously stated. The thickness of the 

 Utica slate is not accurately known. It is supposed to be from 

 seventy-five to one hundred feet. 



