Juneau's icy wonder offers a trip back to the ice age
Mendenhall Glacier, known as "the drive-up glacier" because it can be reached by car, dazzles visitors and makes the region a one-of-a-kind destination. Only about 12 miles north of downtown Juneau, it is the best known of 38 glaciers that feed on the Juneau ice field, a 1,500-square-mile expanse of rock, ice and snow. Bigger than Rhode Island, the ice field is a remnant of the little ice age, a period that started 3,000 years ago and lasted midway through the 18th century. The ice field is perpetually replenished by an annual snowfall that often tops 100 feet and boasts snow and ice up to 4,500 feet thick.
Mendenhall Glacier stretches 13 miles from the ice field in the mountains to its terminus at Mendenhall Lake, where the glacial face—half a mile wide, 100 feet thick and electric-blue in color—can be seen from a popular visitor center on the shoreline. Visitors can also take hikes with breathtaking overlooks and hit trails that head to Nugget Falls, a waterfall near the face of the glacier.
Nature on the Move
The glacier possesses a frozen, still grandeur, but it's hardly inert, notes Laurie Craig, a visitor center interpreter. A dynamic, moving force, the glacier is the overflow from the ice field, slowly and inexorably drawn down by gravity from 4,500-foot-high mountains to its terminus near sea level. Moving at the proverbial glacial pace, the ice edges forward at an average rate of a few feet per day, taking more than 200 years to make the journey from upper elevations to the 220-foot-deep lake. "It’s like slow-moving lava," says Craig. "It acquires wrinkles, crevasses and texture as it moves across the terrain."
Mendenhall Glacier doesn't just move. It displays tremendous erosive power as it grinds through the landscape. Scouring debris from valley walls and scraping underlying bedrock, the glacier burrows deep, enduring marks on the topography. Near the visitor center (the first U.S. Forest Service one in the nation), the presence of grooved, polished rocks is evidence of the glacier’s sandpaper-like effects. The glacier also is responsible for the milky, gray-green cast that colors the lake, the result of "rock flour" deposited in the water when bedrock is ground into a fine powder.
Like all of Juneau ice field's glaciers except one (the Taku), Mendenhall Glacier is receding. Since 1765, the glacier has been in a slow, gradual retreat because its rate of melting has exceeded its rate of accumulation. In the 18th century at its maximum advance, the glacier's toehold in the valley extended from its present position to a spot two and a half miles downward.
This isn't such a bad thing though. Today, receding ice has allowed land buried for thousands of years to reemerge and begin a new ecological cycle. At first, bare rock and soil are exposed, but lichens and moss soon appear. Then grass and shrubs emerge, followed by alder, willow and other deciduous trees. Finally, Sitka spruce, western hemlock and other conifers take hold, inaugurating new forest. "These are stages of life," says Craig, and seeing such natural wonder is one of the reasons Alaska is worth visiting.
Mendenhall Glacier is named after Thomas Corwin Mendenhall, a prominent scientist who helped oversee a crucial survey that determined the international boundary between Canada and Alaska. Previously, the famed naturalist John Muir had visited the glacier in 1879 and named it Auk Glacier in honor of a local Tlingit Indian village. Not surprisingly, Muir called the glacier "one of the most beautiful of all the coastal glaciers."
More than a century later, Mendenhall Glacier is still one of the Inside Passage's top natural sights. Like all glaciers, it can be enjoyed as a spectacle flaunting sublime blue colors and ineffable textures. At the same time, it serves as a time capsule, an outdoor classroom showcasing Alaska’s extraordinary geology and climatic history. “This is a neat place,” says Craig. "It’s not just beautiful. You also get to see some very impressive forces that shaped this region."