The marine wilderness of Glacier Bay offers rare opportunities to study the ebb and flow of glaciers. The last of Glacier Bay National Park's four glacial periods, the Little Ice Age, began about 4,000 years ago, and the glaciers that exist in the park today are remnants of this period.

There are several tidewater glaciers and even more alpine glaciers in Glacier Bay. The tallest of these ranges, the Fairweather Range, features mountains that stretch as high as 15,320 feet – taller than Mt. Rainier and Mt. Shasta! In fact, Mt. Fairweather is taller than any of the mountains in the other 49 states. Advancing glaciers flow forward about three to six feet each day. Depending on the length of the glacier and the steepness of the valley it flows through, the ice at the front of the glacier is anywhere between 75 and 200 years old. Snow that fell in the high mountains 200 years ago when the U.S. Declaration of Independence was signed breaks off as ice today.

Temperate rainforest dominates the southern part of Glacier Bay National Park. Many plants are able to live in this coastal area due to the mild, moist climate that has developed in the region over the past 200-300 years. As the forest ages, trees grow taller and their branches form a canopy that shades the ground beneath them. The soil becomes more acidic and swampy, promoting the growth of western hemlock. Spruce does almost as well in these unique conditions.

Over time, the forest canopy becomes more open as trees of different ages and sizes thrive letting more light reach the ground, which allows herbs and shrubs to grow. Rotting tree trunks become “nurse logs” to the young vegetation, providing them with support and nutrients. Old-growth conditions can go on for centuries.

To learn more about this unique and powerful place, visit the National Park Service website.