Aufeis

Aufeis (German for 'ice on top') forms during the winter by the upwelling of river water behind previously frozen ice dams. New ice continues to form on top of older ice and the accumulation can be many feet thick.

We heard several loud booms while we were camped near the Aufeis. It sounded like explosions, but it was the sound of the ice cracking. Tomorrow we have to get to the other side of the ice, but we'll walk around it rather than take a chance crossing it while it's breaking up.

This is called 'candle ice' because of the way it forms into candle-like crystals.