<u have attempted to walk in the lower Arb recently, you may have felt more like you were on a long, winding ice-rink. But on the other hand, it could be worse: it could be almost two miles of ice. That’s right, it’s icy outside—so let’s talk about the Ice Age! From the Cannon River to Minnesota’s 10,000 lakes (there are actually over 15,000 not that anyone is counting), to that hill between Goodhue and the dining hall, the great hunks of ice that passed over our landscape are mostly to thank (or blame) for the landscape we see and use today.
Technically, we are still in the Earth’s fifth Ice Age—a period of time when permanent ice sheets exist at the poles—but 20,000 years ago, the world was colder than it is today (yes, even than those Minnesota mornings) and massive glaciers were rolling over the Carleton Arboretum. Then, around 14,000 years ago, something remarkable happened; right in the middle of Northfield, the glacier stopped and began to recede. Water running off the side of the melting glacier carved a deep valley that now holds the Cannon River. Rocks and boulders transported hundreds of miles south, and rounded from the jostling journey, were dropped into piles that formed the rolling landscape of southeastern Minnesota. And, as the glaciers left, chunks of ice fell off, became covered in soil, and melted to form depressions that now hold the many lakes of Minnesota, including our own little Kettlehole Marsh.
But the story doesn’t stop there: in the millennia following, the first people to inhabit Minnesota moved in the wake of the glaciers, hunting saber-tooth tigers, mammoths and giant sloths that likely once wandered through the Arboretum, and using the soil, borne of fine particles from the barren post-glacial landscape, to grow food, just as we do today.
Who would have thought ice could be so cool? (Or should I say cold?)