- 
				
Which are the forces you 
				think can be responsible for driving plates?
				If the north American plate is driven from below then what 
				should happen to the motion of North America?
 
				- 
				
How would lithospheric 
				thickness effect degree of coupling with mantle?
 
				- 
				
How can we test the 
				assumption that hold simple shear responsible for lithospheric 
				deformation?
 
				- 
				
If the plate is driven by 
				side forces or by below then where do you think orogenesis to 
				occur?
 
				- 
				
Stations in western United 
				States have northeast trending fast directions. What does this 
				fact suggest? 
 
				- 
				
What came first gravity 
				drag-pull, or mantle flow ?
 
				- 
				
 Will north America really 
				stop? 
 
				- 
				
Why the author used a 
				technique based on angular variations of P-wave delays ?
				 
				- 
				
What the anisotropic 
				layers that the deep Canadian Shield consists of ?
				 
				- 
				
Why North America has 
				slowed dramatically throughout the past 100 m.y.?
				 
				- 
				
Does the orientation of 
				minerals supports the mantle role in plate motion ?
				 
				- 
				
How is that related to the 
				thickness of the lithosphere ?
				How is the dip direction supports the claim ?