When describing glaciers in Wrangell St. Elias National Park, superlatives are hard to avoid. Within its boundaries are enclosed the nation's largest glacial system. Glaciers cover over 25 percent, or approximately 5,000 square miles, of the park. In summer, these glaciers contribute a significant portion of the rivers' high runoff and heavy sediment load. During the winter, glacial melt ceases and many rivers run with clear water.
Glaciers are the headwaters for many of the river systems that flow like arteries through the park. They are heavy with glacier silt and sediment, causing them to braid as one channel begins to fill with sediment forcing the water to switch to a new channel. Glaciers themselves are often referred to as rivers of ice. They flow down mountain valleys and, in the case of tidewater glaciers, into the sea.
Notable Glaciers in Wrangell-St. Elias:
The Hubbard Glacier is North America's largest tidewater glacier. Here are some facts about it!
Why Does the Hubbard Glaicer Advance and Retreat?
During the summer of 2002 the Hubbard Glacier near Yakutat pulsed forward, closing Russell Fiord from the sea. The massive ice dam that formed was later breached and washed out by water retained behind it, reconnecting the fiord to the ocean. Rather than being an event that took hundreds of years, this drama played out in the course of a couple of months.
Glaciers will always try to reach a balance between the amount of ice they gain to the amount of ice they lose (equilibrium). Simply, when the glacier gains more ice than it loses, it will advance. Conversely, when a glacier loses more ice than it gains, it retreats.
Glaciers gain ice by accumulating snow and burying it to transform into glacial ice. This is a four-part transformation; first snow, then to an ice called neve, then to a denser ice called firn, and finally to glacial ice. This transformation is due to burial pressure applied from the snow accumulating above. Once the ice becomes more than 150 feet thick the ice can behave plastically, and start to flow under the influence of gravity.
The Hubbard Glacier is currently advancing while most glaciers are retreating worldwide. The Hubbard Glacier will and does react in an opposite fashion to most glaciers in a warming climate. As the global temperature increases, more precipitation is created locally. As this precipitation hits the St. Elias Mountains, it rises and cools, changing to snow. This increase of precipitation is what allows the Hubbard Glacier to advance.
There are several excellend websites about glaciers. Here are a few we recommend:
Investigate Glaciers - Explore glaciers through images, panoramas, video, sounds, and text.
The Life of a Glacier by the National Snow and Ice Data Center
Glaciers in Alaska's National Parks by the National Park Service Alaska Regional Office
Seeing & Exploring Glaciers
Hikers should not attempt to cross glaciers without proper equipment including crampons, ropes, and iceaxes. Even the gravel covered moraines will turn slick and dangerous during or after a rain.
Please discuss your plans with a park ranger before undertaking glacial travel or mountain peak ascents. Guides are available for these activities and can be used to gain experience.
A great way to see the park's glaciers and icefields is from the air. There are a number of flightseeing operators that offer a variety of spectacular tours.
The only way to see the Hubbard Glacier is to visit Yakutat, Alaska. You can see it by boat or by air. Several cruise ship companies include the Hubbard Glacier on their Alaska cruise itineraries.