Glacial Erosion

Did you know....

The closest glacier to SFU is only 30 km away? It's a tiny cirque glacier in the Obelisk Peak area, in the headwaters of Coquitlam Lake.

The closest glacier to SFU that you'd find on a large-scale map (1:250,000) is on the north side of Meslilloet Mountain? It's only 34 km away.

The closest glaciers we can SEE from SFU are on the south side Mamquam Mountain, just 55 km away? You can see them if you look north from the bus loop.

What you need

• Ice cube trays
• Playdough, pasticene or modeling clay
• Water
• Sand
• Small twigs
• Tray of sand

What to do

The day before you plan to do the activities, make up three sets of ice cubes. A: Use water only. B: Put a layer of sand in the bottom and fill with water. C: Put some small twigs in the bottom and then fill with water.

Activity 1

1.    Take one plain ice cube and push it over the surface of the tray of sand. What happens? (You should have made a furrow in the sand depending upon how smooth the surface was and how hard you pushed the ice cube). Repeat this with rough surfaces. Make some ridges of sand then try pushing the ice cube parallel to the ridges and across the ridges.

2.   Repeat this using other surfaces, such as aluminum foil, wood. What happens on these harder surfaces?

Activity 2

1.    Take a plain ice cube and run it over the surface of a piece of playdough (or other modeling clay). What happens?

2.   Repeat with one of the sandy ice cubes (sandy bottom surface against the clay). Repeat with the ‘twiggy’ ice cubes. (Make sure the twigs are at the bottom, again the clay surface.) Was there any difference?

What’s going on?

The sand and twigs made scratches and grooves in the clay surface. This is like real glaciers, which contain boulders, sand or other materials frozen in them. What happens at the snout (end) of a glacier as the ice melts? Look at pictures of glaciers, or recently glaciated valleys, to help find answers to this question.