LIMESTONES OF WESTERN TENNESSEE 699 



Linden bed fauna at Linden is the equivalent of the upper or 

 Pyburn fauna at Pyburn Bluff, and overlies, stratigraphically, the 

 lower or Camarocrinus fauna at that bluff, then the upper part of 

 the Linden bed overlaps the lower part; suggesting the growth 

 of the Cincinnati geanticline during the earlier part of the 

 Paleodevonic. The studies so far made upon the Linden bed are 

 insufficient to determine the matter. 



No trace of the Upper Silurian or Cayugan has so far been dis- 

 covered in the Tennessee River valley or in the Mississippi River 

 basin. 



From these observations it appears that the growth of the 

 Cincinnati geanticline began in times preceding the Devonian, 

 that its growth continued during early and middle Devonian 

 times, and that it had reached considerable proportions in times 

 preceding the deposition of the Chattanooga black shale. 



The stratigraphic evidence secured so far is not sufficient to 

 demonstrate the existence of the Cincinnati geanticline in Ordo- 

 vician times. However, a study of the areal distribution of 

 Silurian and Ordovician faunas suggests that the Cincinnati 

 geanticline had its origin during Ordovician times, and that its 

 effect upon the geographic range of faunas was considerable 

 already during the earlier part of the Silurian^ This method of 

 determining the location of geologic barriers by means of a 

 study of the distribution of faunas promises to be of the highest 

 value, since it appears capable of demonstrating the existence 

 and probable location of barriers even in cases where the strati- 

 graphic evidence is defective,' although, of course, it is eminently 

 desirable that the results of paleontological research be corrobo- 

 rated by stratigraphical evidence. 



Data are accumulating which suggest the existence of an ele- 

 vation of land, or dome, in southwestern Tennessee during the 

 later part of the Ordovician and at the beginning of the Silurian. 

 According to the researches of Ulrich and Bassler, the Utica is 

 absent in central and southern Tennessee ; the Lorraine, how- 

 ever, is represented by equivalents of the Fairmount, Bellevue, 



' Ulrich AND SCHUCHERT, "Paleozoic Seas and V>z.xx\&x%,'' Report of New York 

 Paleontologist for 1 90 1, No. 2. 



