120 TWENTY-SEVENTH REPORT ON THE STATE MUSEUM. 



nomenclature a well-recognized group of strata, well known 

 and clearly defined for more than one thousand miles in ex- 

 tent of country, spreading diagonally over nearly or quite 

 fifteen degrees of latitude, while its undulating and repeated 

 outcrops, owing to anticlinal erosion, add some hundreds of 

 miles more to its known exposures. 



The results of tedious and careful field investigations in the 

 working out of hundreds of sections in various parts of the 

 country, supplemented by the study of large collections 

 of numerous species of fossils, and the final comparison 

 of all these fossils, from the far north-east on the St. Lawrence 

 to Tennessee on the south-west — from the Mississippi valley 

 on the west, from the States of Iowa, Illinois, Wisconsin, the 

 islands of Lake Huron, and Canada West (Ontario), to- 

 gether with the more critical study of the rocks and fossils 

 within the limits of the State of New York — are all to be set 

 aside, and a simple assertion, unsupported by sections, by 

 fossils, and I may say by a single fact of importance, is to be 

 substituted for all the labors of thirty years. 



This assertion comes from a, gentleman holding the import- 

 ant and responsible position of State Geologist of Illinois, whose 

 name is associated with so much of the geology and paieon 

 tology of the west as to give currency, if not authority and 

 authenticity, to what he may say : — and certainly he ought 

 not, without good reason and authentic data, make such asser- 

 tions nor put such a paper before the American Association 

 for the Advancement of Science. 



But will the geologists of the United States accept this so- 

 called determination of the identity of the groups of strata 

 known as the Niagara and the Lower Helderberg % * 



But Mr. Worthen is not original in this view of the relations 

 of the two groups of strata. He has merely revived an old 

 and discarded error. The same assertion was long ago made 

 in the Geological Reports of Pennsylvania and elsewhere ; and 

 was at one time the generally accepted belief among geolo- 



* Of late "years, in certain quarters, it has been only necessary to contradict what 

 has heen done in the State of New York, or by persons in her employ, both in 

 geology and palaeontology, to have the statement accepted on bare assertion. I 

 might instance examples too numerous to be creditable to the acumen and good 

 sense, to say nothing of the scientific ability, of those who propose or accept such 

 conclusions. 



