STRATIGRAPHIC TAXONOMY 649 



based primarily on rocks holding the Calciferous fauna when they werj 

 limestones and the Levis graptolites when they were shales. 



In the past decade or so much has been learned concerning the fauna 

 and stratigraphy of the Chazy. It is known that the Chazy rests uncon- 

 formably on the Beekmantown and that in stratigraphic position, and 

 to a certain extent also in faunas, its two lower divisions (Day Point 

 and Crown Point) correspond in general to the lower and middle Stones 

 Eiver group of Tennessee and Kentucky and of the Appalachian Valley 

 from Pennsylvania southward; hence that its taxonomic relations are 

 with the succeeding formations rather than the preceding. Dana having 

 properly referred the Stones Eiver group of Tennessee to his "Trenton 

 period," which corresponds very nearly to the Ordovician of the present 

 work, his reference of the Chazy to the Canadian, when viewed in the 

 light of recent knowledge, becomes merely an excusable error in corre- 

 lation. And, as it is now practically certain that the faunal sequence 

 in Newfoundland is confused at the critical point, either by overthrust- 

 ing of Canadian black shales with Levis graptolites on much later Ordo- 

 vician limestone or by some other means, the reasons for associating the 

 Chazy with the Beekmantown "Calciferous" are entirely removed. The 

 upper boundary of the Canadian may, therefore, be drawn beneath the 

 Chazy without departing in any essential respect from the intention 

 and practice of the author of the term. 



But the lower boundary of the Canadian of Dana and authors gen- 

 erally also requires redefinition and revision. The Calciferous of twenty 

 or more years ago, in fact up to several years after 1899, when Clarke 

 and Schuchert^^ proposed the geographic term Beekmantown to take 

 the place of Calciferous, is not exactly the same as it is understood to 

 be today. The recent work of Cushing, Kuedemann, and the writer 

 in New York has sho\\Ti that rocks varying greatly in age have been 

 referred to the Calciferous^^ ; also that the typical Calciferous in the 

 Mohawk Valley is mostly Ozarkian. 



The "Calciferous" rocks of the Mississippi Valley, likewise, are nearly 

 all Ozarkian, and the same is true of a few localities in Canada, notably 

 3 miles east of Beauharnois, that Billings and Logan referred to the 

 Calciferous; but the formations in New York and Canada which fur- 

 nished most of the fossils that became known as the Calciferous — now 

 Beekmantown — fauna are of Canadian age. The Ozarkian dolomites 

 beneath them in the Champlain Valley being almost unfossiliferous, and 

 as the unconformity of the contact with these underlying dolomites was 



«« Science, new ser.. vol. x. 1899. pp. 876-877. 



" E. O. Ulrlch and H. P. Cushing: New York State Mus. Bull 140. 1910. 



XLIIT— Bill. Geol. Soc. A>r.. Vol. 22. 1010. 



