324 ANNUAL EEPOKT SMITHSONIAN INSTITUTION, 1912. 



to mark a pause in the uplifting movement. This beach is well 

 developed at Algoma Mills, Ontario, and is called the Algoma beach. 

 At that place the Nipissing beach is about 85 feet and the Algoma 

 about 50 feet above Lake Huron. The Algoma beach has been found 

 at many places farther south, and is a little more than halfway up 

 from the present shore to the Nipissing beach. 



On the north shore of Lake Superior there is a beach of moderate 

 strength standing in about the same relation below the Nipissing. It 

 may be the Algoma, but it seems more likely to be a beach belonging 

 to the Lake Superior Basin alone and determined by the outlet of 

 that lake at Sault Ste. Marie. It has been called the Sault beach, and 

 appears to swing on the isobase of that place as on a nodal line. It is 

 submerged on the south shore of Lake Superior and around the west 

 end. It is beheved to he along the submerged base of the Pictured 

 Rocks. The Algoma beach appears to be due to a pause in the 

 upUfting movement, but the Sault beach is due in all probabiUty to 

 a relatively steady condition of the lake level arising from the estab- 

 Ushment of the barrier and outlet at Sault Ste. Marie. 



LAKE ERIE. 



After Lake Erie became separated from Lake Ontario it ceased to 

 be a glacial lake, and from that time on it was entirely independent of 

 the ice sheet. By the time the separation had been accompHshed, 

 following the fall of Lake Lundy, the basin of Lake Erie had prob- 

 ably been brought nearly to its present attitude. In this time it 

 has also had two low stages, during which it was not receiving the 

 discharge of the upper lakes. These times were when the Kirkfield 

 and North Bay outlets were active. The Fort Erie beach, declinhig 

 gently westward along its north shore from Fort Erie, Ontario, where 

 it is 15 feet above the lake, is the correlative of Early Lake Algon- 

 quin and probably in part also of the Port Huron stage of the greater 

 Lake Algonquin. The two low-stage beaches made in the basin of 

 Lake Erie during the Kirkfield stage of Lake Algonquin and during 

 the Nipissing Great Lakes lay very nearly in the same plane, and 

 both are now everywhere submerged. 



EVIDENCES FOR AND AGAINST PROGRESSING ELEVATION OF THE 



LAND. 



In the northern part of the upper lakes there are many evidences, 

 such as the newness of the modern shore line and the newness of 

 the mouths or lower courses of streams, hke the Nipigon and other 

 northern rivers, wliich strongly suggest recent or progressing emer- 

 gence. Gilbert found what he beheved to be evidence of progress- 

 ing change in the records of the lake gauges, and he estimated the 

 rate of differential uphfting, but recent investigations have made 



