Ranger Jeff Pietka specialty is the Tidewater Glaciers of Glacier Bay. How is a tidewater glacier different from other glaciers in the Park? Pietka says a tidewater glacier flows down the mountainside and ends in the sea “it’s like a river … of ice,” he says. The tidewater glaciers around the Bay are really shaping the valley and the mountain below it. The tidewater glaciers flow out of the Fairweather Mountains, which feeds the glaciers with snow and ice. Thanks to the unique conditions of warm air coming off the Pacific and rising into the mountains where it cools and provides precipitation, the glaciers see about 150 feet of snow every year that feeds into the tidewater glacier. And most of it sets up from year to year and gets compacted into ice on the glacier. As it compacts, it gains weight and it’s the weight that begins to push the glacier down the mountain, crushing everything in it’s path to rocks and boulders and glacier flour – a silt so fine it becomes suspended in the water.
The rocks builds up at the base into a moraine. And it’s the moraine that keeps the Glacier healthy and advancing. Once the moraine falls into the deeper water and sea water reaches under the glacier, the glacier begins to retreat. That’s what happened 250 years ago, the glacier filling Glacier Bay retreated, having been exposed to the relatively warmer sea water. The process has an ebb and flow to it over the centuries, some glaciers retreat while others advance. That’s what make Glacier Bay one of the most interesting places on earth.
Click the arrow below to hear this podcast:[audio:http://www.hollandamerica.com/assets/cruise-vacation-onboard/TidewaterGlaciers.mp3]
Listeners can download all 16 of the Glacier Bay podcasts, or only a specific audio file, onto a personal iPod, MP3 or portable media player before embarking on a Holland America Line Alaska cruise to Glacier Bay. Preloaded podcasts on iPods also are available on board for checkout. To access the complete “Glacier Bay Ranger Podcast Anthology” click here.
Paul Lasley and Elizabeth Harryman, travel writers, broadcasters and regular contributors to the Holland America blog, worked with the National Park’s rangers, scientists and naturalists to allow you this rare insider’s view into the science and wild beauty of Glacier Bay National Park.