BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 

 Vol. 1, pp. 481-500, pls. 11-13 May 7, 1890 



THE CUBOIDES ZONE AND ITS FAUNA; A DISCUSSION OF 

 METHODS OF CORRELATION. 



BY HENRY S. WILLIAMS. 

 {Read before the Society December 28, 1889.) 



CONTENTS. 



Page. 



Introduction 481 



The Principles of Correlation 482 



The Cuboides Zone 485 



The Cuboides Fauna ^ 48G 



The Frasnien Fauna of Gosselet 488 



Homotaxy and Contemporaneity 489 



The Tully Limestone and its Fauna 489 



Comparison of New York Species with European Forms 492 



Comparison of European Species with American Forms 494 



The Transition between the Hamilton and the Tully Faunas 490 



Review of the Argument 498 



Conclusion 498 



Discussion 499 



Introduction. 



Geologists are well acquainted with the fact that during certain portions 

 of geologic time, through a system, or several systems it may be, the rocks 

 for a considerable region may indicate conspicuous uniformity in their geo- 

 logic history. Thus, the Appalachian basin, as it is called, extending from 

 New York to Alabama, and several hundred miles in width, presents in all 

 essential features great uniformity in the nature of the deposits, in their 

 order, and in the sequence of the faunas for the large part of the Paleozoic 

 time. 



When, however, comparison is made of sections in widely separated regions, 

 as those of Nevada and New York, although the general sequence of faunas 

 is similar, the details of the geologic history, as recorded by the stratigraphic 

 series, are entirely distinct. 



In the first case, whatever differences are recorded in different pails of the 

 region, may be directly correlate! by the intermediate sections, and each 



LXIV— Ruix. Gf.oi,. Soc. Am., Vol. 1, 1889. ( 181)* 



