430 O. B. HOPKIXS STRUCTURAL FEATURES OF PLAIXS OF ALBERTA 



The conclusion seems justified that the folding and faulting at Mud 

 Buttes and similar localities is surficial and does not affect the underlying 

 formations. 



AYhat force could produce intense deformation of surface beds without 

 affecting the underlying ones ? Slumping will not account for it, as the 

 folding shows too much regularity in strike and dip and involves the 

 entire mass of the hills. The only competent force that can be called 

 upon to explain surficial disturbance of the strata is the continental ice- 

 sheet which moved southward over these hills in Pleistocene time. 



