98 STUART WELLER 



of the province the entire Upper Devonian epoch is represented by a 

 black shale which has been variously called the Ohio shale, the New 

 Albany shale, or the Chattanooga shale, which is widely distributed 

 in southern Ohio, Indiana, and Illinois, in Kentucky, Tennessee, and 

 northern Mississippi, Alabama, and Georgia, and extends westward 

 into northern x'\rkansas. Throughout the southern portion of the 

 province this black shale rests unconformably upon the subjacent 

 strata, and in some parts of Kentucky, at least, is unconformable 

 upon Middle Devonian limestones. In the Ohio Valley the fauna in 

 the basal portion of the black shale indicates its Genesee age,' but as 

 the shale was a transgressing formation toward the south and south- 

 west, its age in these directions becomes younger and younger, and at 

 the extreme limits of its extension it may even be younger than any 

 true Devonian, and be contemporaneous with the basal member of the 

 Mississippian. 



While these monotonous black shale conditions obtained in the 

 south, a series of waves of faunal immigration were penetrating the 

 northeastern portion of the province. In the Portage of western New 

 York occurs the Intumescens fauna^ characterized by its numerous 

 goniatites of the type of Manticoceras intumescens. This fauna, like 

 the Cuboides fauna of the Tully limestone, is of European origin. The 

 path of its migration into New York is believed by Clarke to have been 

 the same as that of the earlier fauna, by way of the Interior Continental 

 Province, but Ulrich and Schuchert^ express the opinion that it came 

 in from the Atlantic basin by an eastern route. Following the Intu- 

 mescens fauna, in the same general region, is a fauna in the High Point 

 sandstone, at the extreme summit of the Portage group, characterized 

 by Pugnax of the type of P. pugnus, which is another European immi- 

 grant, and which has many species in common with the Lime Creek 

 shales of the Interior Continental Province in Iowa. Succeeding the 

 High Point fauna is the typical Chemung fauna with Spirifer disjunc- 

 tus and its associates, which again are European immigrants, but are 

 associated with other forms which are of Hamilton derivation. 



1 For a summation of the opinions which have been held in regard to the age of 

 the black shale, see Girty, Am. Jour. Sci. (3), VI, 385, 386. 



2 Clarke, "The Naples Fauna in Western New York," Sixteenth Ann. Rep. New 

 York State Geol., 1896, pp. 31-161; also Mem. N. Y. State Mus., No. 6. 



3 Loc. cit. 



