414 J. IP. Sprocrr-Tn^cr* ahmt L„h Ontario. 



rock-bottomed trough which extends from the Georgian Bay 

 to the eastern portion of Lake Ontario. The descending por- 

 tion of this ridge may be represented by a contour of 250 feet 

 above Lake Ontario, to which it approaches at Scarboro Heights. 

 The composition of the whole thickness to lake level (more 

 than 300 feet) is here shown and consists mostly of stratified 

 sand and clay, with two intercalated beds of boulder-bearing 



'There is a resemblance between the Artemesia ridges and 

 the so-called Kettle Moraines of Wisconsin, Coteau des Prairies 

 and Coteau de Missouri. There is a general parallelism be- 

 tween these ridges. The Artemesia gravel reaches 1700 feet 

 above the sea — a height as great as portions of Coteau des 

 Prairies. 



From the structure of both the "Artemesia Gravel " and ''Oak 

 Ridge," there is no evidence of their being of morainic charac- 

 ter. The deposits of the Artemesia gravel are simply around 

 the high rocky floor of this portion of the country, and mark 

 the recession of the waters in more or less perfect contour lines, 

 with most of the material of local origin. 



Whatever barriers may have separated the lake region from 

 the sea, there seems no doubt that the whole area was sub- 

 merged beneath the sea level to at least 1700 feet, for no glacial 

 lake could account for the high level beaches. From the char- 

 acter of the deposits there appears to have been but little float- 

 ing ice — perhaps not much more than the ice-fringes of the 

 present day. The highlands south of the lakes do not rise to 

 any such height as to permit a small amount of floating ice to 

 barricade them to the height of several hundred feet. 



As the continent was rising, the waters of this inland lake 

 had manv ating with the exterior sea, across 



Ohio and New York, besides that by way of the St. Lawrence. 

 However, local oscillations probably played an important part, 

 but to what extent cannot yet be well determined. 



Below 1200 feet above sea level of to-day, the principal old 

 outlets are by the valley of Cayuga Lake, at 1015 feet; by 

 Seneca Lake vallev, at M',;, jWt ;' h v tin- Mohawk River, at 484 

 feet, and by the present St, Lawrence River, at 247 feet above 

 mean tide." In Ohio, Dr. Newberry enumerates various other 

 outlets at iWi, ims, '.m><>, i)l<) and 940 feet above present ocean 

 level. 



There is a remarkable connection between these old outlets 

 and the beaches which rise a few feet above them, in that they 

 are conspicuous and are mo^t widespread- 

 Many of the transported bowlders of crystalline rocks may 

 have been carried by the floating ice of the great lake of the 

 time; but the explanation of the Hudson River pebbles and 



