Glacial Speed

Margerie Glacier, Glacier Bay National Park, Alaska

We experienced a very hot summer in the Kansas City area with temperatures in the upper 90s and even into the 100s. Now, that it’s September, we’re finally getting some nice weather.  I was lucky enough to escape the heat for a week in July when I visited Alaska, where the locals jokingly complained about a heat wave in the 70s.

To cool myself upon my return to sweltering temperatures, I enjoyed some of my photographs of Alaskan glaciers.  Margerie Glacier (in photo above) is one of several glaciers remaining in what was once a single vast ice sheet covering the Glacier Bay area of Alaska. We often hear of the rapid retreat of glaciers, particularly in the past few decades. I haven’t thought of the rapid advance of glaciers being part of relatively recent history, but Glacier Bay, which is at the top of the Alaskan panhandle, is only about 250 years old. It was carved in the early to mid 1700s when a relatively dormant glacier began to move rapidly. Its movement was described as being “as fast as a dog could run,” according to the National Park Service rangers stationed in Glacier Bay National Park. Glacier Bay is the result of the climate in the Little Ice Age, which reached its maximum extent in 1750.

Click on this map of Glacier Bay National Park to see a larger view.

I’d always thought that glaciers moved slowly and steadily slow. The glacier scours the earth as the massive ice field moves forward inch by inch and then slowly retreats, leaving debris in its wake and in mountainous coastal areas a glacier carves a deep bay or a fjord, such as Glacier Bay.   I won’t be using the cliche “glacial speed” any more now that I know how quickly glaciers can Advance.

Margerie Glacier is stable. Johns Hopkins Glacier is actually advancing. Both are remnants of a much larger glacier.

The Tlingit people who lived in Glacier Bay before it was a bay had to leave the valley as that glacier quickly advanced. According to the National Park Service, the Tlingit’s landscape “is very different from today’s marine bay — it was a grassy valley coursing with salmon-rich streams and scattered forests. Looming in the distance, a great glacier sits dormant, pausing before the cataclysmic advance that will force these people from their homes around 1750.”

This section of a U.S. National Park Service brochure, shows the advance and retreat of the glacier that carved Glacier Bay in Alaska. Click on the photograph to get a larger view.