Glaciers

The first glaciers I saw in Svalbard were from the plane window as we descended into Longyearbyen.

On the second day of our expedition aboard the National Geographic Explorer, we entered Hornsund Fjord. This was the the very same area I viewed from my plane window with multiple glaciers feeding into one spot. A Fjord is a valley that is carved by a glacier and is a deep trough. This trough is fed by tributary glaciers. The glaciers form from snowfall. If there is constant cold and a build up of snow, then over time the snow compacts into ice. There needs to be 10-15 meters of snow to form glacial ice and once this piece of ice is big enough to move it is officially a glacier.

While I have always lived in New England and witnessed snow year after year, I had no idea that different types of snow have different names. A glacier begins as regular snow but as it compacts it goes through stages. Stage 1 is fresh snow. Stage 2 is Corn Snow and is defined as snow that goes though repeated melting and freezing. The snow resembles large-grained rounded crystals. It is the type of snow that forms a nice crust that you can walk on top of. Stage 3 is firn. Firn snow has the appearance of wet sugar. It is the snow that has been left over from previous seasons and has recrystallized into a denser substance. Finally, there is the glacial ice.

Try this LEGO Activity: Build up the four layers one brick at a time and then have the students compress their "snow" into a glacier by exchanging the four bricks into four plates. As students replace each layer discuss the transformation from regular snow into glacial ice using the terms corn snow and firn. This model will help cement the idea of how a glacier is formed. Don't be afraid to write labels on the LEGO bricks with a Sharpie and keep the model around for future lessons. In addition you could talk about how glaciers calve into the ocean revealing blue ice.