1 91 3] The Moraine Systems of Southwestern Ontario, 57 



THE MORAINE SYSTEMS OF SOUTHWESTERN ONTARIO.* 



By Frank B. Taylor. 



{Read 26th April, IQ13) 

 Introductory. 



At its maximum extent the front of the Wisconsin ice sheet reached 

 nearly to Cincinnati, Ohio, and covered completely the whole province 

 of Ontario. It is now well known that the movement of the ice sheet 

 from its centres of growth in the North was due to the force of gravity 

 acting upon a mass of ice so vast and piled up to so great a height that 

 it had at all times a continuous surface slope descending from its centre 

 to its edge. This surface slope was the fundamental condition of its 

 movement. Its motion was a slow, semi-viscous, flowing move- 

 ment in which the ice, like water, was always seeking a lower level. To 

 a certain extent, but imperfectly, it obeyed the laws of hydrostatics. 

 The fact that it filled the Great Lake basins, completely overflowed the 

 highlands between them and even overtopped mountain peaks, like the 

 Catskills, the Adirondacks and the White mountains, shows the enormous 

 thickness which the ice must have had in Labrador in order to have had 

 a descending surface slope that would pass over the tops of such moun- 

 tains as Mt. Washington in the White mountains and Mt. Marcy in the 

 Adirondacks. On the basis of such facts it has been estimated that at 

 its maximum the ice at its centre in Labrador must have been at least 

 13,000 feet thick and may have attained a thickness of 15,000 or 20,000 

 feet. Fragments of Potsdam sandstone were carried from low levels 

 near the north end of Lake Champlain to the tops of the Adirondacks. 

 The possibility of the performance of such feats by the ice used to be 

 strenuously denied. But knowing the nature of glacial movement and 

 the enormous thickness of the ice, it is easy to see that detritus could be 

 carried up hill to or over the top of any object — any hill or mountain — 

 over which the ice mass was moving. 



Since the ice was plastic and moved under the action of gravity, it 

 was influenced largely by the topography of the land over which it 

 moved. Thus, at its maximum the Wisconsin ice sheet reached nearly 

 to Cincinnati, but in western New York reached only to Salamanca. 

 But Salamanca is on the Alleghany plateau near its front and stands high 

 above the lake basins to the north. The front of the plateau extends 

 southwest along the south side of Lake Erie to the vicinity of Cleveland, 

 Ohio. This great bulwark of the land guided the movement of the ice 

 toward the southwest and caused it to overspread the lower plains of 



* Published by permission of the Director of the Canadian Geological Survey. 



