Photographer: Piero Armando
Summary Author: Martin Richard
Look at this river of ice!
It’s a glacier, which is almost 14 miles long. It’s the longest glacier in the Alps, the Altesch Glacier, in Switzerland. It’s a mountain glacier.
Another word for mountain glaciers is Alpine glaciers, because Alpine is an old word for mountain.
Mountain glaciers start in the high mountains and move down, into the valleys. How do glacers form?
Glaciers grow where the snow piles up and does not melt. Glaciers melt at their low end. If more snow piles up on the high end than melts on the low end, the glacier grows. If more melts than piles up, the glacier shrinks.
Mountain glaciers flow downhill, but they do not flow quite like water.
The top part of the glacier is brittle It cracks like ice. But underneath the top of the glacier, the weight of all the ice pushing down changes the way the ice flows. The bottom of the glacier flows like syrup. Very, very, very cold syrup.
The brittle top is carried along by the slowly-flowing bottom. Because it is brittle,the top can break. The cracks in the ice are called crevasses. They can be very deep. Snow can cover and hide them, which is very dangerous to hikers and climbers.
The glacier tears the mountain down! In two ways.
The first way is, the glacier plucks rocks right off the mountain! At the head of the glacier, water seeps between the glacier and the mountain. It seeps into the cracks of the rocks. When it freezes, it cracks the rocks, and the glacier grabs the pieces of rock and carries them away.
The second way is, the glacier scrapes the rocks away. The rocks carried by the glacier scrapes the rocks on the sides of the valley. That wears both rocks down.
The glacier carries all that rock and dirt and it piles up along the sides of the glaciers. A huge pile of dirt and rock piled up and left by the glacier is called a moraine. Two glaciers can come down two valleys and join. They merge, and so do their moraines, carried by the glacier. Look at this picture. See the darker stripes in the glacier? That’s a line where two glaciers joined together!
If you want to learn more about this picture, you can read about it here: Aletsch Glacier in Switzerland It is not written for kids, but you can try it.
We will look at more pictures of glaciers and write about them for kids, right here. Then we will choose another subject, and write about it for you, every week.