Kenai Fjords National Park is home to some of the most magnificent glaciers in Alaska. The Harding Icefield covers more than 700 square miles in Kenai Fjords National Park and is the source of over 35 named glaciers. Several different types of glaciers can be seen from our cruises, including tidewater, piedmont, hanging, and cirque glaciers.
The three main ingredients in the formation of a glacier are time, snow, and cool summers. The Gulf of Alaska sends lots of moisture to Southcentral Alaska, giving the Harding Icefield an average of 60 feet of snowfall every winter. Glacial ice forms relatively quickly in Alaska, in just four to ten years. When snow first falls, it is about 80% air. As time passes and that snow receives additional snowfall on top of it, more and more air is compressed out. Once the snow has compacted to a point where it is only 50% air it is called firn, part of a process called firnification. Given more time and more snowfall, the snowpack will reduce to 20% air, and at that point it has become glacial ice.
One of the most common questions about glaciers that we get on our cruises is: why is the ice blue? White light includes a spectrum of different wavelengths that are represented by all colors of the rainbow. When light hits denser ice, the denser ice absorbs all colors of the wavelengths except the shorter, high-energy blue wavelength. The blue wavelength is reflected back, making the ice appear blue.
A tidewater glacier occupies a fjord and terminates in the ocean. The terminus lies below sea level and generally has an almost vertical face (often over 1,000 feet high) that sheds off huge chunks of glacial ice. This spectacular display, called calving, can vary dramatically throughout the year.
Tidewater glaciers seen on our cruises: Holgate Glacier, Aialik Glacier, Northwestern Glacier
A piedmont glacier is a broad valley glacier that terminates on an open slope or plain beyond the mountains. Piedmont glaciers recede and create dry outwash plains or freshwater lakes at their termini.
Piedmont glaciers seen on our cruises: Bear Glacier
Hanging glaciers flow down out of mountain valleys and are generally larger at the head and smaller at the base. The terminus of a hanging glacier lies above sea level.
Hanging glaciers seen on our cruises: Godwin Glacier, Porcupine Glacier
A cirque glacier is a small glacier that occupies a bowl-shaped depression between mountain valleys. They are generally small and circular or oval in shape. There are many cirque glaciers throughout the area, most of them unnamed.
Cirque glaciers seen on our cruises: Porcupine Glacier, Spoon Glacier, Prospect Glacier