On a trip to Quartz Lake, visitor to Alaska Garrett Ast once plucked a caterpillar from a twig.

On a recent river trip in northern Alaska, scientists from the University of Alaska Museum of the North found a lost world, a time of “polar forests with reptiles running around in them.”

If we climb high enough above this tumble of gray water, we can see a wedge of blue-white ice withering into the mountains.