Meares Glacier, Unakwik Inlet

Meares Glacier, Unakwik Inlet

by | Jun 2, 2022

Meares Glacier starts at an elevation of about 7200 feet (2195 m) in the Chugach Mountains between Mount Michelson to the north and Columbia Peak to the south and trends generally southwest for 16 miles (26 km) to Unakwik Inlet in Prince William Sound, about 47 miles (76 km) northeast of Whittier and 40 miles (64 km) west of Valdez, Alaska. The tidewater glacier was named in 1909 by Ulysses S. Grant and Daniel F. Higgins of the U.S. Geological Survey for 18th century British Naval Captain John Meares, a well-known Pacific Northwest explorer and fur trader. Meares spent the winter of 1786-87 in Prince William Sound while on a trading expedition aboard the English vessel Nootka. Unakwik Inlet extends northward for about 22 miles (35 km) from the main body of Prince William Sound. The Alutiiq name was first reported in 1898 as ‘Unaguig Inlet’ by U.S. Army Captain Edwin F. Glenn, and the spelling was changed in 1909 by Grant and Higgins. The fjord is from 1 to 3 miles (1.6-4.8 km) wide, and the depth of water ranges from 534 feet (163 m) at the glacier terminus to over 1,000 feet (305 m) near the inlet entrance but shoals to only 6 feet at an ancient terminal moraine that probably represents the maximum ice advance during the Holocene Neoglacial period. The geology of Prince William Sound consists of one of the world’s largest accretionary complexes that has been known by various names such as the Chugach terrane, Chugach and Prince William terranes, and most recently the Southern Margin Composite terrane. The terrane is comprised of rocks that formed during the Late Cretaceous and Paleogene age and are represented north of the Contact Fault at Miners Bay in upper Unakwik Inlet and underlying Meares Glacier by the Valdez Group. These rocks consist primarily of complexly deformed metasedimentary greywacke, siltstone, and shale generally considered to be deposits of turbidity currents in a deep oceanic trench.

The heavily glaciated north coast of Prince William Sound experienced repeated ice advances through the Neoglacial Period, and despite this hostile environment, humans have inhabited the area for thousands of years. The earliest known occupation of the sound is based on archaeological excavations from a prehistorical village site called Uqciuvit at the northern end of Esther Passage in Port Wells, about 16 miles (26 km) west of Unakwik Inlet. This village was inhabited between about 4400 and 3300 years ago. Very little is known about the people of this pre-Neoglacial phase, except that they hunted sea mammals, used red ochre, and were familiar with slate grinding. Historically, Prince William Sound was occupied by eight geographic groups of Chugach people, the easternmost group of Eskimos. Although these groups shared the same language and culture, each was politically independent with its own leader and principal village. The Kiniklik people were one of the eight original Chugach tribes. In 1956, Frederica de Laguna inventoried the settlements of Prince William Sound based on surveys conducted in 1930 and 1933 and described a prehistorical village of the Kiniklik people in Unakwik Inlet on the west shore near the mouth of the fjord. The main historical village called Kiniklik was situated at the end of the peninsula separating Unakwik Inlet from Eaglek Bay to the west and was already abandoned in 1930. In 1790, the Spanish explorer Salvador Fidalgo reputedly visited Unakwik fjord. In 1794, Lieutenant Joseph Whidbey with the Vancouver Expedition sailed into the bay and found the upper part blocked by ice, but noted the noise made by ice falling from the glacier front. In 1905, Grant and Higgins visited the bay and returned in 1909 to document the glacier. They photographed the terminus and described it as 0.8 miles (1.3 km) wide and over 300 feet (91 m) high, and slowly advancing based on vegetation being overrun by ice.

Meares Glacier has been advancing since it was first observed in 1905. William O. Field reported that the terminus of Meares Glacier from 1910 to 1931, advanced 820 to 985 feet (250-300 m) with an annual advance of 40 to 50 feet (12 to 14 m) per year, and from 1931 to 1966, advanced 650 to 1400 feet (200 to 425 m), with an annual advance of 20 to 40 feet (6-12 m) per year. In the 56 years between 1910 and 1966, the terminus advanced between 1640 and 2215 feet (500-675 m), an average advance of 30 to 40 feet (9 to 12 m) per year. In 1910, Ernest F. Bean, who for two summers was a member of an expedition organized by the National Geographic Society, determined that the water depth ranged from 634 feet (193 m) about 0.5 miles (0.8 km) south of the glacier terminus to over 1,000 feet (305 m) near the entrance of the inlet. He also found topographic evi­dence of several former glaciation episodes. The fjord walls are straight and steep, and there were numerous hanging valleys from which streams cascaded to the sea. The rock walls showed an abundance of ice grooving, plucking, and striation. Bathymetric soundings proved conclusively that the Meares Glacier formerly extended much farther south and had eroded the inlet. Bean also determined that the depth was too shallow at the terminus for the glacier to be floating and was still actively scouring the inlet floor. Since the height of the ice front is at least 200 feet (61 m) and the depth of the water is 634 feet (193 m), there is a total thickness of 734 feet (224 m). If glacier ice floats in seawater with one-sixth of its volume above water, the total thickness of the glacier would have to be 1,200 feet (366 m). In 2000, the terminus of Meares Glacier was observed to be slowly advancing and pushing down trees, although observations from the air showed evidence of ice thinning at the margins of the terminus. Between 1910 and 2000, the terminus advanced about 0.7 miles (1.1 km), an average advance of  40 feet (12.2 m) per year. In the 36-year period between 1966 and 2002, the glacier advanced a maximum of about 1800 feet (550 m) or an average annual advance of about 50 feet (15 m) per year. This atypical glacier advance is explained by the relatively large snow accumulation zone of 30,000 acres (12,140 ha) compared to the ablation zone of 5,000 acres (2,000ha). Read more here and here. Explore more of Meares Glacier and Unakwik Inlet 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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