Climate change causes glacial river in Yukon to change direction

from CBC News…

Glacier retreated so much that its meltwater switched course, in an event not documented in modern times.

Climate change has caused the massive Kaskawulsh Glacier in the Yukon to retreat so much that its meltwater abruptly switched direction, in the first documented case of “river piracy” in modern times.

Instead of flowing into the Slims River and then north to the Bering Sea, the water has changed course and now flows south toward the Kaskawulsh River, the Gulf of Alaska and the Pacific Ocean, scientists have found.  Read more…

Hands-on Glaciation using “Glacier Trays”

GlacierTray1I can’t say for sure, but I think I’m seeing a resurgence in hands-on learning and modelling in the classroom. From my perspective, I have introduced a lot more of it this year and, when I stop and reflect on it, I understand why. In this computer age of geotechnology, on-screen animations and Google Earth, it’s easy to forget that kids benefit from having those hands-on tactile learning experiences provided by “real-life” models.

For the last few years, in the Physical Patterns unit of my Grade 7 World Studies course, I’ve made great use of Google Earth and Google Earth elevation profiles in the teaching of the various landforms and patterns around the world. In small groups, students create a landforms investigation, explore and illustrate it using Google Earth and elevation profiles before telling us about human interactions with their assigned landform. All well and good, but each year after teaching it I find my students still disconnected from the landform. It was a thing on a screen rather than being something in real life. So, my goal this year was to introduce landform models – somehow…

I love it when ideas spawn ideas. Coincidentally, I was speaking with a parent who is also a teacher and she mentioned using ice cubes on a tray of sand to replicate continental glaciation in the classroom. Wow – did I feel dumb. I’ve been teaching geography for almost 25 years and had not come across this. That being said, I’ve only had an opportunity to teach glaciation a few times – not when teaching in Africa, but a bit in England and here in southern Ontario.

A week of thinking and surfing and a quick trip to the dollar store and we were outfitted, ready to go for the total cost of about $25 (that’s Canadian, so about $15 US dollars!!) I purchased 4 plastic serving trays – one for each group – about 30cmx50cm and 3cm deep. I also bought a number of small square plastic “leftovers” containers with lids. You see, rather than using your typical ice cubes, I thought – hmmmm, we need more realistic glaciers. Freezing ice in these 12x12cm containers would make larger “ice sheets” or “lobes”. I even tried freezing ice in a large cookie sheet to make an even larger sheet. While it broke apart easily enough to fit onto the glacier trays, it didn’t convey the idea of a glacier any better than the square blocks. Trial and error at work here!

Besides having sand in the trays, I also wanted to replicate what glaciers do to bedrock. Here in southern Ontario, many students have cottages up on the Canadian Shield in places like Muskoka, Haliburton, the Kawartha Lakes and along the eastern shore of Georgian Bay – prime places to find striations on the exposed bedrock. After having a good think, I added modelling clay to the shopping list. It worked brilliantly. I buried a section of modelling clay in the sand, leaving the top of it exposed.

To ensure some striations would show up, I made the glaciers more realistic by adding a pinch or two of sand and a few small pebbles (aquarium gravel works) to each “glacier”. This not only added to the reality of the glacier (“Eeewwww – why is the glacier dirty?” “Why are there pebbles in the ice?” were two common questions), but upon melting, we had erratics – another common feature here in southern Ontario. The other two features I wanted students to be able to re-create were terminal moraines (easy-peasy – just push the ice along through the sand) and kettle lakes as we have a number of them around us and North America’s largest is just few kilometres south.

To this end, I also used regular-sized ice cubes made in an ice cube tray and tried using a hair dryer to melt the ice more quickly. Sure enough, it did a great job melting the ice, although we had to be careful not to blow sand around, which brings me to the last pice of the puzzle: plant mister bottles. We used these to dampen the sand to give it some “clumpability”, making the progress of the glaciers over the “land” more realistic. It had the added effect of reducing the amount of blowing sand with the hair dryer.

Glacier-RecedingOne thing I tried at home when setting all of this up was to freeze the glacier tray before introducing the glaciers. I thought this would provide a more realistic landscape for the glaciers to flow over. However, when I pushed the glacier over the frozen sand with enough force to push up some sand ahead of it, the whole frozen block of sand slid on the smooth plastic bottom of the tray. In retrospect, the bottom of the tray needs some kind of ridge or set of ridges to help hold the frozen sand in place. Also, it might help if the tray has had a chance to thaw slightly – perhaps spraying the surface with water would help. Hmmmmm – I need to think more on that one.

Interlobate moraine

Interlobate moraine

Puddling in the glacier tray

Puddling in the glacier tray

Finally, the day came. With the glaciers packed in a cooler, off to school I went. The students were prepped the previous class by examining photos of various features and completing a diagram illustrating continental glaciation features. For the lab, I challenged them with trying to replicate as many features as they could. One group wanted to have two glaciers on the same table and within a few minutes, without realizing it, they had interlobate moraines – a perfect teachable moment. They finished the lab by drawing a labelled field sketch of their glacial landscape, then cleaning up – all in an hour.

The same lab became a little more challenging for my second class as now the glacier tables were quite damp. Interestingly, though, this created the conditions for puddling behind the terminal moraines – again, a perfect teachable moment as that’s exactly what we have evidence of here in southern Ontario. This second class even had water in their kettle lakes; in the first class, the meltwater was simply absorbed into the sand.

Successful? – Definitely. The students not only enjoyed themselves, but had a much better understanding of the forces of erosion and how various landforms in our region were formed. The enjoyment factor can’t be understated; in a contest between a paper/screen lesson vs a hands-on-get-dirty-modelling lesson, the hands-on wins every time. Given the low cost and the short time needed, there’s really no reason why not to do this in the classroom. It certainly makes the learning real!

More ideas for glaciers and erosion in the classroom:

Good Luck and have fun!