t'OURTH REPORT OF THE DIRECTOR I907 (y-J 



the river flow must have been inferior to the Rome level, which is 

 now 440 feet. 



After at least many centuries of flow this predecessor of the 

 St Lawrence river, carrying the overflow of the second stage of 

 Iroquois waters (or Hypo-Iroquois), was extinguished by the ice 

 recession opening a yet lower pass, on the north slope of Covey 

 hill. This third phase of the Iroquois waters was short-lived and 

 of rapidly falling levels, the river flow past the ice front only terrac- 

 ing the sandstone slope. 



When the waters were lowered about 450 feet below the Gulf 

 channel, they became confluent with the oceanic waters, and the 

 Ontario basin was occupied by the Gilbert gulf, a branch of the 

 Cham plain or Hochelagan sea. 



On Friday the parties from Alooers and Plattsburg met at Chazy 

 where Professor Gushing and Dr Ruedemann showed the visiting 

 geologists many interesting features of the Ghazy limestone, the 

 local succession of beds, the characteristic fossils, the faults, and the 

 dissection which have produced the present topography. After 

 supper, while waiting for the train to Plattsburg, the party sat on 

 the hotel porch and listened to a talk by Dr R. Ruedemann on 



The Lower Siluric paleogeography of the Champlain basin 



The relations of the faunas of the Beekmantown, Fort Gassin, 

 Ghazy, Black River, Trenton, and Utica beds to those of the At- 

 lantic and Pacific basins and the Mississippian sea were discussed, 

 and by means of these relations the probable marine connections of 

 the Qiazy basin and the Levis channel with the oceanic basins traced. 

 It was suggested that the Beekmantown sea, while extending as far 

 as the Newfoundland embayment, held an American epicontinental 

 fauna; that the Fort Gassin fauna did not reach Ganada, but 

 flourished in the Appalachian trough to the south of the Ghazy 

 basin, and also spread westward into the epicontinental sea. The 

 typical Ghazy fauna is thus far recorded only for the Ghazy basin 

 and the southern Appalachian trough. It extended as far as the 

 Mingan islands, and came probably from the Atlantic basin. There 

 is also evidence that it had some connection with the American 

 epicontinental sea. 



The Black River and Trenton faunas, while largely American in 

 their aspects, contain European species as the first of the Lower 

 Siluric; and the connection of the Trenton sea with the Atlantic 

 ocean can not be doubted. In Utica time the channel became so 



