694 PROCEEDINGS OF THE BALTIMORE MEETING 



Schuchert), through which it migrated northeastward into the New York area, 

 having at the time the elevated Appalachian land area lying east of it. 



8. So far as North America is concerned the Helderberg-Oriskanian fauna 

 appears to have had its origin from the North Atlantic, outside the Appa- 

 lachian land. 



9. To explain the Hercynian-Coblenzian combination in Europe, there ap- 

 pears to have been a mingling of these two general faunas (the Helderberg- 

 Oriskanian and the Onondaga-Hamiltonian), which were more or less distinct 

 on the North American continent. 



10. To explain these last three facts seems to require a North Atlantic center 

 of distribution for the Helderberg-Oriskanian fauna, and a South Atlantic or 

 equatorial center of distribution for the Onondagaian fauna. 



11. The passage from the Grande Greve limestone into the sandstone and 

 conglomerates of the Gaspe sandstone series indicates an upward movement of 

 that edge of the continent beginning during the life of the Oriskanian fauna, 

 and its remaining above sealevel over the eastern province. 



12. The distribution of the Oriskany deposits over New York state indicates 

 a rising of sea bottom into land before the close of Oriskany, or during the 

 time in which the closing Oriskany, the Esopus, and Schoharie grits were 

 being deposited. 



13. The coral reefs of the early Onondaga show a depression over New York 

 state and along the Connecticut- Saint Lawrence trough, extending as far east 

 as lake Memphremagog and Chaudi§re, Quebec, in early Onondagaian time, 

 not, however, depressing the interior province below sealevel, and the trough 

 probably did not reach the North Atlantic basin to the eastward. 



14. Although there are indications of the mixed fauna both sides of this 

 trough (to the south in northern Maine and at Gasp§ and to the north of it at 

 Saint Helens, Montreal), the faunas of both of these limestones as reported 

 appear to be pure Onondagaian, like the corresponding fauna seen in the more 

 western outcrops with which they are supposed to have been connected. 



15. The southern extension of the Onondagaian, in Illinois, Indiana, Ken- 

 tucky, appears to show closer admixture with types of Helderberg-Oriskanian 

 type than does its northern extension in the New York basin. 



Conclusions 



These arguments seem to support the hypothesis that the York River beds 

 at Gaspe contain a marine fauna of Oriskanian type not younger in age than 

 the Schoharie grit of New York state. On this hypothesis marine communica- 

 tion with the Atlantic basin must have been cut off with the cessation of that 

 fauna ; the upper fauna of Saint Helens and Cote Saint Paul was of not later 

 age than the York River beds at Gaspe; the Onondaga faunas of Owls head 

 and Chaudidre entered from the west, having migrated around from the south- 

 west through the Indiana basin, and the Connecticut-Saint Lawrence trough 

 did not open out into the Atlantic basin in Onondagaian time. 



The explanation of the mingling of Hamiltonian types with the Oriskanian 

 fauna in this eastern province is found in the meeting of the North Atlantic 

 fauna of Oriskanian type with the South Atlantic fauna of Hamiltonian type, 

 coincident with the rising of the land which caused the continental border of 

 the continent to transgress eastward. 



