Thursday, September 24, 2015

Alaska's Kenai Fjords National Park

Alaska's Kenai Fjords National Park is located at the farthest edge of Alaska's Kenai Peninsula, just southwest of Prince William Sound. It is a locale where the ice age is still lingering, though it is gradually receding. The park covers a total of 669,984 acres. Exit Glacier is one of only a few Alaskan glaciers that is road-accessible, and the only section of the park accessible by car is the Exit Glacier area which has short trails and informational signage.

It became a national monument by presidential decree in 1978 and promoted to national park status in 1980.  In 1968, a party of seven made the first documented crossing of Harding Icefield traveling west to east on snowshoes and skis in seven days. They completed their traverse at the appropriately named Exit Glacier. But the area had been inhabited for thousands of years by Alaskan natives, notably by The Alutiiq 1000 years ago.

The Harding Icefield and its outflowing glaciers cover 700 square miles of the Kenai Mountains in glacier ice. Created more than 23,000 years ago during the Pleistocene Epoch, the Harding Icefield was a small piece of the vast ice shelf that then covered much of South-central Alaska. Exit Glacier is one of 38 glaciers that flow out from the Harding Icefield.

As I drove into the park, I began seeing signs along the entrance road showing where the glacier used to extend to in previous years, with signs marking every decade or so.  Using aerial photos taken since 1950, coupled with biological calculations prior to the photographs (as lichen growth), they have measured a total glacier retreat of 1.25 miles since 1915.

Below are the photos I took as I approached the glacier, and the walking path is obvious heading to and then alongside the glacier.

Alpine glaciers such as this form when more snow falls on mountain peaks during the year than melts during the summer. As the snow pack builds up and thickens, its immense weight compresses the layers of snow below which turn to ice.  As the layers on top accumulate, the glacier grows, and ultimately the overwhelming weight of the ice begins to push the lower ice down the mountainside, and as it very slowly flows downhill, it scrapes the ground beneath, scouring the valley floor and carrying with it the dislodged rock and debris, or glacial till or moraine, which is the black sediment you see alongside the edge of the glacier.

Exit Glacier retreated 187 feet during 2014, with 80% of the loss occurring during the summer months. From 1815 to 1999, it retreated an average of 43 feet per year.

I also took an all-day commercial day cruise out of Seward in order to experience the namesake fjords of Kenai Fjords National Park. Below are some scenery photos from that boat excursion...

Leaving Seward...

Holgate Glacier...

The beautiful dark blue color is the result of snow being compressed by subsequent layers atop it as it becomes part of the glacier. Air bubbles are squeezed out and ice crystals enlarge, making the ice appear blue. The red, orange, yellow, and green wavelengths of light are absorbed so the remaining light we see is composed of the shorter wavelength blue and violets. This is the main reason ocean water is blue -- it owes its intrinsic blueness to selective absorption in the red part of its visible spectrum.

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