METHODS OF CORRELATION 463 



that I entertain the hope and belief that I shall soon succeed in completing 

 a work on the subject that will settle the problem finally by proving the 

 essential equivalence of the Chattanoogan and Kinderhook series. 



But I was speaking of disagreements arising from inconsistencies in 

 method and practice. Perhaps the most troublesome are those incon- 

 sistencies which have resulted from the application of the strictly dias- 

 trophic method in one area and the purely paleontologic in another. 

 They are distressingly troublesome because they tend without real cause 

 to align the advocates of the two methods against each other in a blind 

 and stubborn struggle in which the paleontologist fears for the very life 

 of his principles. This is wrong, because our sole aim should be to win 

 the truth without regard to whose method is adopted. 



PREVAILING INCONSISTENCIES IN DRAWING THE ORDOVICIAN-SILURIAN 



BOUNDARY 



A live instance of this kind is found in the Ordovician-Silurian bound- 

 ary which was drawn in New York and in the Appalachian region gen- 

 erally, according to strictly diastrophic criteria. However, in Ohio and 

 adjoining States to the west and south certain highly fossiliferous beds 

 that are now known to correspond to unfossiliferous clastic deposits in 

 New York, which have always been classified as Silurian, were placed in 

 the Ordovician column. There was no intent to discredit the New York 

 classification, for that was correctly and firmly based on criteria — of the 

 kind now termed diastrophic — whose dominance in the case of systemic 

 boundaries was recognized then and has never been denied since; and 

 none knew that the fossiliferous Richmond formations finger into the 

 barren Queenston division of the Medina series. The geologists of the 

 day acted simply as the information then in hand demanded, and as they 

 had observed none of the many faunal breaks now recognized in the 

 sequence of Ordovician and early Silurian rocks exposed in the Cincinnati 

 dome, there was no more reason to question the apparent general unity 

 of the Cincinnatian and Richmond faunas than to suspect a time break 

 in the Ohio section between the Richmond and the overlying "Medina" 

 and "Clinton." Therefore, as the Richmond fossils compared much bet- 

 ter with the Cincinnati-made conception of the typical American Ordo- 

 vician fauna than they did with the succeeding Niagaran fossils, which 

 chiefly contributed to the prevailing conception of a Silurian fauna, there 

 was nothing else to do but to place the Richmond at the top of the 

 Ordovician. 



But now, since we have learned many facts then unknown — and since 

 we understand that in estimating the faunal differences then supposed to 

 distinguish the Silurian from the Ordovician no account whatever was 



