UPPER CAMBRIAN TRILOBITE FAUNAS 

 OF NORTHEASTERN TENNESSEE 



By 



FRANCO RASETTI 



The Johns Hopkins University 



PART I. STRATIGRAPHY AND FAUNAS 



The purpose of this paper is both to describe the fossils and to 

 present them in their proper stratigraphic setting. In the study of the 

 Cambrian of the southern Appalachians, there has been in the past 

 little collaboration between geologists and paleontologists. Strati- 

 graphic work was done by geologists who had only a secondary inter- 

 est in fossil collecting; on the other hand, almost all the species 

 described by Walcott and by Resser were derived from old collections 

 that bear more or less precise locality labels but no accurate indication 

 of the stratigraphic position. In his paper on the Cambrian of the 

 southern Appalachians, Resser (1938a) tried to refer the Upper 

 Cambrian fossils to several zones. This assignment was essentially 

 based on the occurrence of the genera in question in better-understood 

 areas of the United States, chiefly the Upper Mississippi valley, and in 

 a broad sense succeeded in providing an approximately correct time 

 order for the fossils of the southern Appalachians. However, none of 

 the finer details of the time succession could be determined. 



The obvious procedure was therefore to locate well-exposed, rela- 

 tively undisturbed, fossiliferous sections, to collect fossils from care- 

 fully measured horizons, and to rely on these alone, and not on the old 

 collections, in establishing the faunal succession. Many of the previ- 

 ously known Upper Cambrian trilobites from Tennessee were thus 

 collected again from known strata; those that could not be found 

 seldom represent more than slightly variant forms related to the ones 

 of ascertained age. A number of new forms were discovered. In gen- 

 eral, the collections are much larger than the ones previously in ex- 

 istence, and provide indications on intraspecific variability in popula- 

 tions from a single bed and similar questions that cannot be discussed 

 on the basis of a few scattered specimens from different localities. 



SMITHSONIAN MISCELLANEOUS COLLECTIONS, VOL. 148, NO. 3 



