When a glacier retreats, it leaves behind a land scrubbed clean of life. On barren rocks and debris called moraines, there is no soil—only a fresh slate upon which to build a new world.
From the 1300s to the 1850s, Earth experienced a Little Ice Age. Glaciers advanced on terrain that previously had been uninhabited by ice. What is now Alaska’s Glacier Bay National Park and Preserve is some of that turf.
Just 250 years ago, Glacier Bay—in the words of the National Park Service—was all glacier and no bay. A massive river of ice, about 100 miles long and thousands of feet deep, occupied the entire area.
A “tidewater glacier,” such as the Margerie Glacier in Glacier Bay National Park and Preserve, is fed by snow—enough so that the glacier pours out of the mountains and down to the sea.
Today, that glacier is retreating north. Fewer than a dozen, smaller tidewater glaciers remain. Sequestered at the heads of their inlets in the upper bay, they flow from lofty coastal mountains to the frigid sea, calving colossal shards of ice into the cold waters that transform into diamond-like icebergs.