Download the printable Experiment Sheet here.
Glaciers are essentially rivers of ice. These landforms occur in areas where accumulated snow collects faster than it can melt away each year. Over time this perennial snow packs down into hard, blue glacial ice. As the ice accumulates, it gets thicker and heavier, until gravity begins to pull the ice sheet downhill. Precipitation continually feeds the top of the glacier with snow and ice as the glacier flows downhill, much like a river.
The great weight of glaciers causes the ice to grind away at nearby rocks to form a fine sediment called called rock flour, and large rocks from the valley and canyon walls as it moves. This experiment actually simulates what happens when a glacier melts and finally deposits the rock flour (chalk) and large boulders (gravel). When the glacier melts it drops boulders into a deposit called a moraine and glacial rock flour gives mountain lakes their milky color.
Here we use shaved ice to demonstrate what's in a glacier and see how rocks deposits are formed up when a glacier melts, from sugary fine rock flour to large boulders.
Plastic Tub large enough to hold experiment
- In the empty tub place some rocks/gravel to represent loose boulders on a mountain valley floor and walls.
- Add the shaved ice to represent the snowfall, and pack it in.
- Add the crumbled colored chalk to represent sediment carried by the glacier.
- Sprinkle on corn starch to represent rock flour generated as the ice erodes rock below it.
- Add additional “snow” and rocks and apply pressure to represent the pressure of the weight of the snow & ice and freeze overnight.
- Observe your new “glacier” and what it’s made of.
- Then melt it with hot water and see what deposits form, and what the water looks like!
Questions to consider:
- How long do you think this process would take in nature?
- How do you think the addition of extra mass (snow and ice) affects glaciers?
Examples of Glaciers
Mountain glacier terminating in Glacier Bay, Alaska, USA. Credit: National Park Service.