ISS 



Partlll. — The Origin of our Glacial Deposits. 



Earlier views. 



Detritus in modern Bergs and Glaciers. 



Distribution of Detritus through the Ice Sheet. 



The Melting of the Ice and its attendant phenomena. 



Relation of External Configuration of Drift Mounds to the 



rock surface beneath. 

 Water-worn Detritus in Drifts. 

 Formation of Gutta Percha Clays. 

 How the Faults and other disturbances contemporaneous with 



the Till were formed. 

 Contemporaneous Contortion of the Drift. 

 Horizontal passage of Till into Sand and Gravel. 

 Undisturbed Deposits beneath Boulder Clays. 

 Thickness of Drift. 

 Eskers. 



Relation of Eskers and Moraines. 

 Marine Organisms in High-level Drifts. 



Earlier Vieius. — Up to 1874 the explanation of the origin of Till 

 most generally accepted (I mean by those geologists whose acquaint- 

 ance with well-glaciated regions qualified them to judgej was that the 

 Till represented a mixture of debris originating as surface moraines, 

 which had been ground up beneath the ice and there incorporated 

 with other material rasped off the subglacial rock-surfaces by the 

 stone-shod sole of the ice sheet. (Those who really know anything 

 about the glacial phenomena of mountain districts will not expect 

 me to waste their time by discussing here any theories that ascribe 

 the origin of Till to marine action.) It seems to have been 

 assumed that the paste of mud and stones accumulated under the 

 ice in the way just referred to, was dragged about from one spot to 



