Glacier Bay National Park is located in the Alaska panhandle 65 miles west of Juneau. It has 3.3 million acres of jagged mountains, active glaciers and picturesque coastlines along deep fjords.
Glacier Bay National Park was established in 1925 by President Calvin Coolidge. The park was subsequently expanded by President Jimmy Carter in 1978. A glacier is basically a river of ice that flows very slowly. Glaciers originate from packed snow that descends from high snow-capped mountains and drain into the bay. The glaciers break up when they reach the sea and form icebergs that float toward the ocean. The breakup process that produces icebergs is called calving.
The glaciers are now in a prolonged period of retreat. Until 10,000 years ago, the land was covered by ice sheets that repeatedly advanced and then retreated. During the Great Ice Age, the ice sheets reached as far south as the upper Midwest of the United States. Michigan and New York were covered by ice sheets hundreds of meters thick.
A long-term warming trend reduced the ice of what now is Glacier Bay. In 1680, the Huna Tlingit people occupied the area, and there was no Glacier Bay then. There was only a broad valley where a glacier was advancing. The glacier continued to advance during the Little Ice Age, which was a cold interval lasting 100 years that was possibly caused by increased volcanism in the Earth. By 1750 the glacier was jutting into the Icy Strait.
When conservationist John Muir traveled in the area in 1879, the glacier had retreated about 50 miles from where it was 100 years before. Today, you must travel 65 miles into the bay to view the glaciers. Global warming is accelerating the rate of retreat of the glaciers.
A team of National Park Rangers board the cruise ships when they enter the bay. The rangers accompany the ship's crew throughout their excursion. The rangers provide information to the passengers about the park and educate them about preserving the area in pristine condition. Their presence on the boat also assures that the ship's crew complies with all the regulations for preserving the park.
A cruise in Glacier Bay enables you to enjoy an unspoiled natural environment. You can see the mountain slopes covered with green vegetation that manages to get sustenance from the rocky surface. The steep peaks of the mountain are bare because they are too unstable to support vegetation. Small streams between the mountains carry sand and fine silt produced by the freezing and thawing of the mountain's stony surfaces. The sand is deposited in a delta where the stream meets the ocean, and the turbid water flowing into the fjord gives the seawater a chalky appearance.
The cruise ships must travel very slowly in the fjords of Glacier Bay. This prevents the ship from disturbing the wildlife and the fragile glaciers that rest in the water. As the ship navigates the narrow channels, passengers can sometimes observe sea lions resting on floating sheets of ice that have calved from the glaciers, and it is not uncommon to see whales.
The glacier ice contains a geological story. As the ice sheets move toward the sea between the mountains, the glacier picks up rocks and dust along the way. The black layers that are visible in the glacier when it reaches the sea correspond to the path that the ice has taken over many years.