Signs of supercooling:
Terrace dams formed overnight are a sure sign of supercooling. Supercooled water only forms deep in the glacier, below hundreds of feet of ice, so this is evidence that spring wells from deep below, and that gravel and alder hide a lot of ice.
Supercooled springs are fairly common on the lower edge of the glacier, and the most common sign are ice terraces like this. The water is cold enough to freeze to the bottom, so it dams itself off and the turbulence promotes faster freezing. This feedback causes the dam to grow into a distinct terrace, much like mineral terraces that form around supersaturated mineral springs.
Read more about our Life on Ice expedition.
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