652 NEiW YORK STATE MUSEUM 



Maryland, and thence south along Appalachia, the Oriskanian 

 emergence continued to close of Onondaga time; and, as we have 

 already described in considering the Cayugan emergence, af- 

 fected not only the Appalachian Mediterranean but the south- 

 eastern area of the Mississippian sea as well. In middle Vir- 

 ginia emergence began early in Oriskany time, since no true or 

 Upper Oriskany is known in southern Virginia or Tennessee* 

 To the north of Cumberland Md. the Oriskany is unequally 

 developed, but in eastern New York it appears to be the higher 

 portion only that is present. With Lower Oriskany only in the 

 southern extremity, and Upper Oriskany only in the northern 

 end, the movements evidently were directly opposite at the two 

 extremities of the Cumberland basin during Oriskanian time. 

 The land conditions that succeeded the Oriskany in the Cumber- 

 land basin continued till about Marcellus or Middle Devonic 

 time, when the later Devonic deposits of the Skunnemunk inva- 

 sion were laid down. 

 oriskanian Immediately succeeding the Oriskany emergence of the Cum- 



invasion of 



the Mississip- berland basin, there still remained in southern New York a 



pian sea " 



depression through which the Atlantic fauna of the Oriskany 

 invaded the Mississippian province. This invasion, coming in 

 from the southeast (the Esopus, which is only a phase of the 

 Oriskany, is 700 feet thick, according to Ries, 1 in Orange county, 

 N. Y.) spread northward, over the Oriskany, and, after crossing 

 the Helderbergian barrier at Rome, continued on westward by 

 way of Buffalo, where remnants of it are seen in the cement 

 quarries. 2 Finally, the last of this deposit is seen near Cayuga 

 Ont. 

 Onondaga The Oriskanian invasion attained the last locality about the 



invasion 



same time that the Onondaga invasion, coming in from the 

 southwest, arrived there, the result being that the Onondaga 

 and late Oriskany faunas, originally very dissimilar in character, 

 became one, making together what is now known as the eastern 

 Onondaga fauna. 



x Ries. N. Y. state geol. 15th an. rep't 1897. 1898. 1:402. 

 •Grabau. Geol. soc. Am. Bui. 1900. 11:355-62. 



