This is the very first glacier that we explored, and it’s a surge glacier. These are white-water glaciers, moving at up to 10m per day and creating wild peaks across their surface. Glaciers like this will surge for years to decades before settling down again.
I like to think of these as the result of a broken dam: a pressure builds up behind some sort of barrier, and once the barrier breaks, the ice flows violently for a bit before calming down again. The exact causes of surges isn’t clear and so I’m not sure if the metaphor holds (there’s a good chance that it has more to do with the glacier sliding over meltwater at the base of the glacier than an actual dam), but it’s a nice image.