|24 CHAMPLAIN DIVISION. 



from any other Biate, of a distant formation. Ii ia onlj by position, and us fossils, thai it 

 can be recognized, [ts fragile character is quite worthj of aotice ; as bj its inability to 

 withstand the combined action of water and frost, ii is constantly passing into soil. This 

 is especially the case if broken and raised from its beds. Under these circumstances, it 

 ft ■ i iii- an argillo-calcareous soil of the best character. 



Tins mas- is well developed in the valley of the Mohawk ; bul in the Champlain and 

 Hudson, ilisverj imperfectlj known. In the vicinitj of Glensfalls and Sandyhill, it is 

 aized in its place above the Trenton limestone. Ii skirts the valley of the 

 Hudson at Miller's falls; but in this range, especially upon the east side of the valley, it is 

 concealed among the shales, and so much altered by pressure and other disturbances thai 

 it is b\ no in' an- clearly defined. It maj 1"- studied in ilie causes of Loraine in Jefferson 

 county, where ii may be seen in its inferior and superior connections. Its thickness is not 

 less than seventy-five, nor over one hunched feet, [n obtaining this estimate, I have been 

 guided bj the distribution of the Triarthus beckii, and the hthological character of the rock. 

 '1' lie re is less siliceous matter in the mass, which lias received the appellation of Utica slate. 



v} 8. LoBAIHE SHALES. 



The incorporation of the Utica slate \\ iili ilie shales of this section, may be well observed 

 in the deep gorges of Jefferson and Lewis counties. A hand of slate, quite fossiliferous, 

 lies at tie | iasi "i the shales, which is usually considered the superior pari of the I tica slate. 

 Within a few feel of this hand. I have found the Pterinea carinata, which is one of the 

 characterise!' fossils of the shales. The shales are composed of alternating beds of slate n 

 this mass in Now York, similar to the Utica slate, and thin siliceous beds, which become, 

 in the superior portion, thick beds, with far less interposed shale. It forms, strictly speak- 

 ing, thin and thick-bedded sandstones, of which the thick beds were deposited last. 



The distribution of the fossils in this mass is worthy of notice. Proceeding from the 

 fossiliferous band of the Utica slate, the fossils diminish rapidly, so that In the middle and 

 inferior parts ,,f the Loraine shales \n\ few fossils exist ; while at the upper portion the 

 mass becomes highlj charged with organic bodies, though distributed more abundantly 

 through calcareous hands. But then they diminish again ; and when the thick-hedded 

 sandstone appears, thej cease, with lew exceptions. This peculiar distribution, and the 

 confined limits of the fossiliferous beds, render the recognition of these shales, when they 

 lie in proximity to the Taconic system, quite difficult; still, by careful examination for 

 the thin fossiliferous hands, doubts maj he usually removed. 1 say careful examination, 

 for a careless ohserver would probably pass over some highly fossiliferous strata without 

 recognizing them, in consequence of their obliteration outwardly -. and it is only where the 

 stratum is broken in the disturbed part of the formation, that they can be observed. 



In describing this rock, it is hardly possible to separate the thick-hedded mass ai the 

 superior part, from the Loraine shales proper : there is a perfect transition of one into the 



