REPORT OF THE STATE PALEONTOLOGIST 1901 635 



In 1897 and again in 1898, Mr Ulrich made small collections 

 and brief stratigraphic investigations in east Tennessee. Tbe 

 fossils then collected were worked up in leisure moments during 

 the next two years, and, when at last the results were brought 

 together, the suspicion that the Upper Ordovicic strata in the 

 eastern half of the Appalachian valley represent a different 

 geologic province from those along its western edge, had grown 

 to conviction. 



The theory, however, was as yet undefined and hazy in its 

 application, requiring much reading and field work to establish 

 the character, position and extent of the barrier that separated 

 the two basins or provinces. The paleontologic evidence in 

 hand indicated a barrier of great length, dividing off from the 

 interior sea a long and narrow body of water in which sediments 

 were laid down containing remains of faunas having relations 

 to those pertaining to east Canadian and European deposits 

 rather than to those of the interior sea. 



American, Canadian and European literature likely to bear 

 on the questions involved, made a pile so imposing that without 

 help the publication of the discovery must have been delayed 

 indefinitely, had the work been undertaken by a single person, 

 or it must have been brought out insufficiently supported by 

 facts to demand credence. Mr Schuchert therefore undertook 

 the labor of collating facts from published works, while Mr 

 Ulrich continued the more congenial task of gathering additional 

 evidence in the southern Appalachian field. Between us then, 

 the evidence has been carefully weighed, discussed and corre- 

 lated, our original theories being constantly modified and 

 brought into accord with accruing facts till, finally, we enter- 

 tained sufficient confidence in the general truth of the proposi- 

 tion to submit the following summary of results. 



The Appalachian series of folds, of which those only that sub- 

 sequently formed barriers, are discussed in this paper, probably 

 trace their origin to precambric times. Walcott,^ we believe, 

 clearly demonstrated the existence of a lonor trouj?h that dur- Lower car 



^ ° brie trougl 



'U. S. geol. sur. Bui. SI. 1S91. 



