Boulton, 2010

Question 1

Boulton, 2010

What does the model do?

Answer 1

Looked at the dynamics of ice streams of the biis particularly vale of york and discovered that they had a high effective pressure and so moved in almost a bouyant state displaying a fast velocity.

He therefore applied these theories to suggest the BIIS was very unstable during the late devensian and this is one of the factors that led to fast ice sheet loss.

Question 2

Boulton, 2010

What does the model find?

Answer 2

1. The ice sheet lobe advanced to its maximum extent driven by a very low gravitational shear stress of about 5–8 kPa.
2. As such large ice fluxes could not be sustained over the whole terminal zone of the ice sheet, such a high velocity must have been restricted to features such as the Vale of York lobe, which must therefore have acted as an ice stream. There is currently no evidence, however, whether this stream was ephemeral, the result of a surge event or was sustained for a longer period.
3. The effective pressure at the base of the ice stream in its terminal zone was very low. The ice stream was therefore very close to a buoyant state.
4. The subglacial drainage system was a self-organised system largely adapted to the seasonally varying pattern of surface water recharge to the bed.