Objective: Data capture, reduction and analysis about glacier dynamics

In addition to the assigned reading you may find Chap 5 in Vol 1 of Menzies (1995) helpful. I have more technical references if you want them.

Some general notes:

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1. Define the following terms and explain why it is important. (5 pts)

Enhanced creep

Dilatancy

Shear stress

Pure shear

Coulomb equation

2. From your glacier address these questions:

(10 pts) Estimate the basal shear stress t for our glacier. The density measured in 1998 was 0.976 g/cm³,but in 1999 it was 1.057 g/cm³. Be sure that your answer has the correct units.

These photographs give the results from one experement - you are welcome to conduct your own.

image 1	(larger version for printing)
image 2	(larger version for printing
image 3	(larger version for printing
image 4	(larger version for printing

 

(10 pts) Discuss possible sources of error in your estimate.

(15 pts) You estimated the basal shear stress for at least two cases - describe them, their analog in real glaicers and why you got the results you did. 

(10 pts) How does your estiamte compare to that of a typical glaicer? Does our mixture serve as a good model?

(20 pts) Using a piece of wax paper (or pastic) create some hills and valleys - let the glacier do its thing. Discuss the relationship of glacier profile to topography.

• You can use an image of an ice cap in northern Maine, by Alex. 312 k so its big.

3. Some thought questions from the reading:

(10 pts) Describe the efects of water pressure on sliding. Under what geological settings would high water pressures exist?

(20 pts) Which movement processes is more important for glaciers that overran Ohio - sliding, deformation of ice, or deformation of the bed?

4. In case you want more:

Bonus (15 pts) Can you estimate the basal shear stress from measurements taken on the vertical rather than horizonal orientation? Some pages showing that set up and results. (The orgainal volume is 70 ml).

Bonus (20 pts) Estimate the basal shear stress of our glacier resting on a piece of sandpaper.

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