The Hungry Horse News has a fascinating report on a recent Waterton-Glacier Science and History Day session. A presentation by Kelly MacGregor, a geomorphologist and associate professor of geology at Macalester College in St. Paul, Minnesota, discussed the history of Grinnell Glacier over the past 22,000+ years as revealed by core samples from nearby lakes . . .
It’s well documented that the glaciers in Glacier National Park are receding and many have vanished. But when they were bigger, they were likely far bigger — in fact, the iconic Grinnell Glacier once likely extended nearly to what is now Swiftcurrent Lake.
Kelly MacGregor, a geomorphologist and associate professor of geology at Macalester College in St. Paul, Minn., has been studying the ebb and flow of Grinnell Glacier over the past 25,000 years.
Giant masses of moving ice, glaciers are difficult to study on the ground — the carving, grinding and shaping of the landscape occurs beneath them and simply can’t be observed. Glaciers also have a tendency to destroy, or at least alter, their geological tracks. But there is a way to track glaciers over time, MacGregor explained to a packed house at the Waterton-Glacier Science and History Day recently — by taking core samples from the sediments in the lakes that glaciers leave behind. She called the sediment in lakes “nature’s junk drawer” — heaped with remnants from the past.