But Why went somewhere really cool - literally - and we’re taking you along! We visited Sólheimajökull, a glacier in southern Iceland and then talked with University of Iceland glaciologist Guðfinna Aðalgeirsdóttir to discover how glaciers are formed, why they can be different colors, and how they shape the land. (Do you know the difference between a V-shaped valley and a U-shaped valley? Glaciers!) Plus we’ll talk a little bit about why glaciers around the world are retreating at such a fast pace.
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- Glaciers are formed in areas where the amount of snow that falls in the winter doesn’t fully melt the following summer. The accumulation of snow year after year will get more compact and denser, turning to ice and becoming a glacier.
- Glaciers are constantly moving. Once enough ice has formed that it becomes very dense, it starts deforming and flowing under its own weight. If the glacier is on flat land, the ice spreads outwards. (These are dome-shaped glaciers. Ice caps are this type of glacier.) If it’s on a hillside, the ice flows downhill. (These are known as outlet glaciers. They often end in a lake or the sea.)
- At the snout of an outlet glacier, big chunks of ice often break off into a glacial lake or the sea. Those pieces are called icebergs.
- The oldest ice in the glacier will be at the snout because it will have been pushed down and out of the glacier, kind of like a conveyor belt.
- The ice in glaciers can be very old! Glaciers in Iceland are probably several hundred to about 1,500 years old. But Greenland has glaciers that are more like 130,000 years old. And ice that is a million years old has been found in Antarctica!
- Glaciers shape our landscape. All that extremely dense heavy ice moving downwards or outwards kind of acts like a bulldozer as it flows. Over long periods of time, glaciers can dig out valleys, shave off mountain tops and create new mountains with dirt and debris they leave behind.
- If you are looking at a valley and it is V-shaped, that is a valley likely carved by a river. But a big U-shaped or bowl-shaped valley was likely formed long ago by a glacier as it retreated–aka melted.
- Though it’s very dense, glacial ice does contain some air bubbles. And scientists can study those trapped air molecules to determine how much carbon dioxide was in the atmosphere when the ice was formed.
- Glaciers can be different colors. Sometimes the ice looks blue, sometimes brown or black if it is covered with dirt or ash. Glaciers can even sometimes turn pink from a type of algae that grows on the top.
