At the summit of the Exit Glacier trail, we put our packs down and let our eyes sweep across the Harding Ice Field. It looked like a vast lake of white, dotted here and there with the dark, bare rock of mountain peaks pushing up from the ice field like islands.

“What’s that out there?” Barbra asked, pointing far out on the ice field.

“Probably just some person,” I replied, barely looking up.

As the dark object continued to lumber toward us, Barbra finally picked up the binoculars. “It’s a bear!”

Sure enough. On the hike up the trail, we’d spotted a sow black bear with two cubs grazing in an alpine meadow. With the image of the black bear fresh in our minds, it was clear that what we were now looking at was a grizzly. A massive one with a large shoulder hump, probably a male.

We marveled at the speed with which it made it’s way across the frozen landscape, it’s tracks stretching out as far as the eye could see in its wake. He appeared to be heading straight for Exit Glacier, which, we imagined, he would follow until he came to a river where he could find spawning sockeye salmon.

Glaciers are like rivers of ice, pushed down mountains by the weight of the ice fields where they are born. It is not known for certain how deep—how thick—the Harding Ice Field is. Judging from the mountain peaks that surround it, it must surely be thousands of feet thick at its deepest places, and it spawns dozens of glaciers, each one carving its own path in the mountain rock as it flows. Exit Glacier moves at a rate of about one and a half feet each day, grinding out a valley under the tons of ice it carries.