The saying “don’t judge a book by its cover” might be adjusted to “don’t judge a glacier by its surface.” Glaciers are stunning beautiful, dynamic structures the size of mountains, but a lot of what scientists study, and what they really want to better understand, is how glaciers work under the surface. Moulins are just one of the main features that may dominate a glacier’s surface. Moulins are well-like shafts that make up part of the glacier’s internal “plumbing.” As the glacier melts, water flows down the moulins, carrying water through the glacier. The flow of water might meet and merge with another water flow, it might exit via the glacier’s edge, or it might flow into the sea. If the water reaches the base of the glacier, it may also act as a lubricant, allowing the glacier mass to slide more easily against the earth, therefore contributing to glacier mass loss and perhaps sea level rise. So if you are ever standing at the top of one of these beautiful wells of marbled white and blue, first of all, be careful. Then make a wish that we can learn more about what’s going on under your feet, because it will affect us all, from Alaska to Florida.
