Petrified Forest, Unga Strait

Petrified Forest, Unga Strait

by | Jul 22, 2020

Petrified logs and stumps are exposed along the eroding northern shore of Unga Island, about 64 miles (103 km) northeast of King Cove and 11 miles (18 km) northwest of Sand Point, Alaska. Unga Island is the largest of the 20 islands in the Shumagin Islands, about 570 miles (919 km) southwest of Anchorage near the southwest tip of the Alaska Peninsula.

The Shumagin Islands were named after Nikita Shumagin, one of the sailors on Vitus Bering’s 1741 expedition to North America, who died of scurvy and was buried on Nagai Island. The large islands in the Shumagins include Unga, Popof, Korovin, and Nagai Islands. Smaller islands include Andronica, Big Koniuji, Little Koniuji, Simeonof, Chernabura, and Bird. The total land area is 294,641 acres (119,237 ha). The total island population lives almost entirely in the city of Sand Point, on Popof Island.

The petrified forest, much of it below the tide line, covers about 5 miles (8 km) of the beach. On a sunny day, the white and bright petrified tree stumps contrast sharply against the gray-black beach rock. The stumps range in diameter from a couple of feet to about 9 feet (2.7 m) across. These are remnants of a sequoia or metasequoia forest buried as a result of volcanic activity in the Tertiary Period (2-65 million years ago). The petrified forest has scientific significance for the migration of species between Asia and America and helps portray the climate and environment of the Aleutian Arc before humans inhabited Alaska. The site is part of the Alaska Maritime National Wildlife Refuge and was designated in 1968. Read more here and here. Explore more of Unga Strait and the Shumagin Islands here:

About the background graphic

This ‘warming stripe’ graphic is a visual representation of the change in global temperature from 1850 (top) to 2021 (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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