Glacier Terminology

We are passing by the southern boundary of Glacier National Park so let’s talk about glaciers for a few minutes. We cannot see any of the Park’s glaciers from the train – the glaciers are on the northern exposures of the mountains, and we see the mountain’s southern exposures from the train.

What is a glacier? A glacier is a slow-moving river of ice. To be classified as a glacier, a body of ice must be:

• at least 100 vertical feet thick, 
• at least 25 acres in size, 
• and be moving, whether advancing or retreating. 

Glacier National Park has been home to many glaciers. The earliest count of glaciers in this area was in about 18 50. At that time the Park area had about 150 glaciers. 

Our climate has been changing over the past 150 plus years. And today only 25 of those 150 glaciers remain. If these trends continue, all of the remaining glaciers in Glacier National Park are forecast to be downgraded to ice fields or disappear entirely by 2030. The loss of glaciers is undeniable evidence that our climate is changing.