152 References to North American Localities. 



ite, which is imbedded in argillite. It is unquestionably a veg- 

 etable petrifaction, and exceedingly abundant throughout more 

 than two thousand square miles of surface. This being, geolo- 

 gically, the lowes.t rock in North America, which contains organi- 

 zed remains, its meeting with the primitive limerock, is the meet- 

 ing of the primitive and transition strata. 



In tracing the localities of the meeting of these classes, we 

 will begin at West Stockbridge, where we began with the prim- 

 itive limerock ; because the argillite is co-extensive with that 

 limerock. It runs north, and forms the vast prominences called 

 Bird's Mountains, between Rutland and Poultney in Vermont. 

 It continues northerly, with various degrees of elevation, to a 

 great distance into Canada. It runs southerly, on and near the 

 east boundary of the state of New York, curving westerly along 

 the westerly side of Taughconnuck Mountain, its western part 

 forming the banks and bed of Hudson River. Its eastern limit 

 is between Newburgh and the Highlands, where its meeting with 

 the primitive limerock is very manifest. Poughkeepsie on the 

 east side of the Hudson, and Newburgh on the west, stand on the 

 argillite. 



Limit between Transition {HemWy s\eni) and Secondary, lower 

 and upper (Abyssient and Pelagient) rocks. 



In article No. IV, published in Vol. xxxvi, p. 61, and note, p. 

 198, of this Journal, I endeavored to prove that the rock which 

 I had named Corniferous Limerock,* is the best North American 

 standard of reference for making out our equivalents to European 

 rocks; particularly as it is Brongniart's upper transition rock.f 

 Unless state geologists are to abandon geology as a science, and 

 to amuse us with local names, insulated and heteromorphous in 

 character, they must make it their chief object to find out trans- 

 atlantic equivalents, since we cannot doubt, that such may be as- 

 certained. I was delighted (after being panic-struck with some 

 state geologists' reports) to see the report of the legislative 

 committee of the State of New York, (dated April 28th, 1840,) 

 in which the sentiments of the committee cannot be misunder- 



* This name I adopted many years since, as a mere temporary name, because 

 I could not reconcile its characters to mountain limerock, either by foreign de- 

 scriptions or by specimens in Gibbs's cabinet. Now I am satisfied that this name, 

 or some other new name, is essential. See the confusion in De La Beche, Bake- 

 well, Brongniart, &c., among the names grauwacke, lime grauwacke, mountain 

 limerock, &c. 



t I called it the upper rock of lower secondary in some publications. 



