Tyndall Glacier starts at an elevation of about 10,000 feet (3,050 m) in the Saint Elias Mountains near the Canadian border, between Mount Huxley to the west and Mount Saint Elias to the east, and flows generally south-southwest for 13 miles (21 km) to the head of Taan Fjord in Icy Bay, about 160 miles (258 km) east-southeast of Cordova and 68 miles (110 km) northwest of Yakutat, Alaska. The tidewater glacier was named by members of the New York Times Expedition in 1886 for John Tyndall, a physicist and mountaineer who made advances in the understanding of the semi-fluid flow of glaciers. Taan Fjord is in Wrangell-Saint Elias National Park and Preserve and extends about 9 miles (15 km) from the eastern shore of Icy Bay. The fjord has been exposed over the last 50 years by the retreat of Tyndall Glacier and is named after the Tlingit word for ‘sea lion’. The bedrock surrounding Taan Fjord represents the Yakutat Terrane, one of seven terranes that formed near the equatorial Pacific Ocean and sequentially rafted northward on oceanic plates, eventually accreting to North American. The Yakutat Terrane was the last to arrive about 26 million years ago and is still actively accreting to the continent. It consists of sedimentary rocks that accumulated as continental shelf deposits during the Eocene to Pleistocene, and some oceanic volcanic rocks, and is separated from the older terranes to the north by the Chugach-Saint Elias Fault System and the Fairweather Fault.

Alaska currently has 50 glaciers that terminate in the ocean at either a grounded terminus or floating ice tongue. These tidewater glaciers are known to exhibit a repeating cycle of slowly advancing over the course of centuries, until thinning near the terminus initiates a rapid retreat that completes within decades, and then stabilizing only when the glacier has retreated into shallow water. In general, the retreat phase of a tidewater glacier can be triggered by changes in climate; but once retreat is initiated, the glacier’s behavior is only weakly influenced by climate. There are eight glaciers in Icy Bay and presently only 5 reach tidewater. The glaciers in Icy Bay historically shared a common terminus that extended into the Gulf of Alaska until the early 1900s. Since then, the common terminus retreated and separated into smaller individual glaciers that are now up to 25 miles (40 km) from the Gulf of Alaska. Taan Fjord, one of the four arms of Icy Bay, was created by the isolation of the Tyndall Glacier from the glacier system after 1960. The retreat of this glacier occurred in three stages. The terminus retreated about 3.7 miles (6 km) between 1960 and 1969, then 1.2 miles (2 km) from 1969 to 1983, followed by another 6 miles (10 km) of retreat and then stabilization of the terminus by 1996. The rapid retreat of the glacier destabilized the steep bedrock slopes of the surrounding mountains resulting in massive landslides.

Sometime between 1983 and 1996 a large landslide occurred along the fjord wall near the toe of Tyndall Glacier. This landslide consisted of a slump that did not run out a great distance into Taan Fjord. On October 17, 2015, after a period of heavy rains, a seismic event occurred at about 9:18 pm local time and about 200 million metric tons of rock fell over a period of 60 seconds from an escarpment on the north side of the Daisy Glacier valley. The force of this material falling remobilized the older slump debris creating a high-speed landslide that entered Taan Fiord at the toe of Tyndall Glacier. The event generated a local mega tsunami that sheared trees at an elevation of 500 feet (152 m) on a peninsula within the fiord. The wave was big enough to register at the nearest tidal gauge 96 miles (155 km) away. In 2016, another massive landslide occurred in Glacier Bay National Park. Events such as this happen maybe three to five times per year around the world, and Southeast Alaska is the global hotspot. Read more here and here. Explore more of the Tyndall Glacier and Taan Fjord here: