Guyot Glacier, Icy Bay

Guyot Glacier, Icy Bay

by | Jun 24, 2023

Guyot Glacier starts from an elevation of about 6,700 feet (2,042 m) on the eastern flank of Yaga Peak in the Robinson Mountains and flows generally east-southeast for 34 miles (55 km) to its terminus just south of the Guyot Hills on the western shore of Icy Bay in Wrangell-Saint Elias National Park and Preserve, about 146 miles (235 km) east-southeast of Cordova and 76 miles (123 km) northwest of Yakutat, Alaska. The glacier was named in 1886, during an expedition to climb Mount Saint Elias sponsored by the New York Times, by Heywood W. Seton-Karr after Arnold H. Guyot of Princeton University. At that time the glacier filled Icy Bay and was considered a western lobe of the Malaspina Glacier. Glacial retreat has separated this lobe into the Tsaa, Guyot, Yahtse, Tyndall, Agassiz, and several smaller glaciers. This part of the southern Alaska coast consists of a collage of seven tectonostratigraphic terranes that formed south in the equatorial Pacific Ocean and rafted northward on oceanic plates, eventually accreting to Alaska and the North American continent. Each terrane features a distinct stratigraphy and is separated from neighboring terranes by major strike-slip or thrust faults. The most recent arrival is the Yakutat terrane and the bedrock now exposed in Icy Bay represents the Yakutaga Formation that developed as glacio-marine continental shelf deposits during the early Miocene and consists of mudstone, siltstone, sandstone, and diamictite.

The rapid recession of the Icy Bay glacier system has uncovered extensive low areas along the fjord margins that are mantled with glacial drift of the last ice advance. Organic remains include subfossil tree trunks and root systems buried in glacial till. Peat deposits, which also contain tree remains, were the primary source of radiocarbon dates making possible a reconstruction of the glacier advance and retreat in the fjord during the last two millennia. The oldest organic remains sampled in the upper fjord system were aged at 8 AD and 131 AD, indicating that forests occupied the margin of the fjord at least 35 km inland from the coast about 2,000 years ago. These forests were buried by successive ice advances that culminated in the 9th century, and then the glacier retreated to positions similar to today. By the early 15th century, the glaciers of Icy Bay again advanced during the Little Ice Age. An oral tradition of the Tlingit people at Yakutat, who are the Laa xaayík Kwáan, details a major glacier advance in Icy Bay that filled the bay and overwhelmed a village situated at the mouth of the fjord. In 1794, Captain George Vancouver, during his voyage of discovery to the North Pacific, surveyed the coast of Alaska near the present site of Icy Bay and made no mention of a bay but did record the location of an ice cliff. In 1911, the U.S. Coast and Geodetic Survey steamer McArthur commanded by C.G. Quillian, went close to the western edge of the Malaspina Glacier and reported a new bay in the ice at the western edge of the glacier and the survey measured a recession is about 9 miles (14.5 km) and the glacier terminus was 200 to 250 feet (60-75 m) high. Subsequent mapping and aerial surveys have documented the recession of the glacier system into the upper reaches of the fjord and its separation into tributary ice streams that continued to retreat.

Arnold Guyot was a Swiss-American who became a professor of physical geography and geology at Princeton University. He studied at the college of Neuchâtel and in Germany, where he began a lifelong friendship with Louis Agassiz who later influenced his move to the United States. As early as 1838, he undertook, at Agassiz’s suggestion, the study of glaciers, and was the first to announce, in a paper submitted to the Geological Society of France, important observations relating to glacial motion and structure. Among other things he noted the more rapid flow of the center than of the sides, and the more rapid flow of the top than of the bottom of glaciers. He described the laminated or ribboned structure of the glacial ice and ascribed the movement of glaciers to a gradual molecular displacement rather than to a sliding of the ice mass as commonly held at that time. His extensive meteorological observations in America led to the establishment of the United States Weather Bureau. In 1945, Harry H. Hess, who collected data using echo-sounding equipment on a ship he commanded during World War II, showed that some undersea mountains had flat tops. Hess called these undersea mountains ‘guyots‘, after Arnold Guyot. Read more here and here. Explore more of Guyot Glacier and Icy Bay here:

About the background graphic

This ‘warming stripe’ graphic is a visual representation of the change in global temperature from 1850 (top) to 2022 (bottom). Each stripe represents the average global temperature for one year. The average temperature from 1971-2000 is set as the boundary between blue and red. The color scale goes from -0.7°C to +0.7°C. The data are from the UK Met Office HadCRUT4.6 dataset. 

Credit: Professor Ed Hawkins (University of Reading). Click here for more information about the #warmingstripes.

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