G20 PROCEEDINGS OF BOSTON MEETING. 



The fourth paper was read by title. 



THE ANCIENT STRAIT AT N I PISSING 

 BY F. B. TAYLOR 



Contents. 



Page. 



Introduction 620 



Beaches 621 



The Nipissing Beach 621 



Beaches at higher Levels 622 



Thibeault Beach 622 



McEwen Beach 622 



Nelson Beach : 622 



The uiisubmerged Area 623 



The south Shore of the Strait , 624 



The Ohnaping Delta 624 



Ancient Nipissing Island 625 



Conclusions 626 



Introduction. 



One of the most interesting and significant chapters of modern geologic research 

 in America has been the gradual unfolding of the story of postglacial changes of 

 the Great lakes. Deserted shorelines have been traced with more or less continuity 

 around all their coasts and several abandoned outlets are already v^'^ell known. It 

 was my privilege recently to visit the site of one of these and bestow some study 

 on its appearance and surroundings. First in August, and again in September of 

 the season just past, I went to North bay, in the Province of Ontario, to see the 

 country in the vicinity of the ancient outlet at lake Nipissing. In August I was 

 accompanied by Dr F. Savary Pearce of Philadelphia. It is the object of this 

 paper to give a short description of what was observed on those occasions. On 

 account of limited time and the roughness of the country it was not possible to 

 make more than a brief reconnaissance, and it was partly because of the indecisive 

 results of the first visit that the second one was made. 



The existence formerly of an outlet for the Great lakes at lake Nipissing had 

 been regarded by me as an established fact; but it was still an open question 

 whether the waters of the great postglacial submergence rose above the level of 

 the outlet river. "The only information on the subject which had ever come to my 

 knowledge was from a conversation with Mr G. K. Gilbert at Indianapolis, in 

 August, 1890. Mr Gilbert had then just returned from lake Nipissing and had 

 examined the bed of the ancient outlet. He expressed his belief in the existence 

 of the river and added that he thought he saw terraces on the hills back of North 

 bay at an altitude of 200 to 300 feet above the lake, but that he had not examined 

 them closely. This agreed in a general way with an hypothesis which I had en- 

 tertained for some time previous and according to which I had estimated the 

 probable height of the highest shoreline at lake Nipissing at an altitude of at least 

 400 feet. To pursue this inquiry was the chief object of my visits. 



My measurements were made with an aneroid ; but care was taken to determine 

 the weather variation and eliminate it as far as possible. The datum for the 

 localities near North bay was the Canadian Pacific railway station at that place. 

 On the profile of the road this is given as 635 feet above the "Summer level of 



