The hike to Mendenhall Glacier is like walking back in time.
Unlike Antarctic glaciers, Alaska's glaciers are surrounded by forested landscapes. As you get closer to the glacier the earth below your feet is newer and newer, becoming exposed to sunlight and open air for the first time in tens-of-thousands of years as the glacier recedes.
You begin the hike surrounded by a lush forest of tall spruce and hemlock. As you get closer to the glacier, the plants around you shrink and change to younger forest to dense alder forest to shrubs and short plants to lichens and moss. Eventually at the base, there is nothing but rock beckoning for new life to take root!
In a few hours hike you can experience a complete forest succession. At the base of the glacier, I recommend taking big dramatic steps and pretending you are a cosmonaut exploring a young alien planet waiting to be inhabited by life. The West Glacier trail in Juneau, Alaska is an ethereal experience.