Aialik Glacier, Kenai Fjords National Park

Aialik Glacier, Kenai Fjords National Park

by | Feb 11, 2022

Aialik Glacier flows southeast for about 8 miles (13 km) from the Harding Icefield in the Kenai Mountains to tidewater at Aialik Bay in Kenai Fjords National Park, about 66 miles (106 km) east-northeast of Homer and 16 miles (26 km) southwest of Seward, Alaska. The glacier was named after the bay in 1909 by Grant and Higgins of the U.S. Geological Survey. The name of the bay is derived from the Alutiiq word ‘Ayalikskaya’ obtained by Russian fur traders. Aialik Bay is a fjord about 5 miles (8 km) wide and extends south for 22 miles (35 km) from the terminus of Aialik Glacier to the Gulf of Alaska with depths reaching 966 feet (294 m). The shoreline is indented by many small bays and coves that represent drowned glacier-carved cirques. The bedrock surrounding Aialik Bay consists mostly of rocks in the Chugach terrane partially comprised of fine sediments in the Valdez Group that filled an ocean trench and lithified as turbidites about 75-55 million years ago. The turbidites were subsequently intruded by igneous oceanic basalts, and shortly afterward, the terrane was accreted to the North American Plate and intruded again by granitic plutons about 55 million years ago. The Valdez Group is a widespread unit along the coastal region of Southcentral Alaska that consists primarily of highly deformed partially metamorphosed sedimentary rock including greywacke, siltstone, and shale. The turbidites are represented by layers generally ranging from a few centimeters to a few meters thick, to locally massive beds as much as tens of meters thick. Aialik Bay is flanked by the Harris Peninsula to the west and the Aialik Peninsula to the east, where the Aialik Pluton is exposed as granitic outcrops at many offshore islands along the Kenai Fjords coast and extends northward for more than 37 miles (60 km) into the Harding Icefield where it is exposed in many nunataks. During the Last Glacial Maximum of the Pleistocene, the Harding Icefield was part of a Cordilleran ice sheet that covered Alaska and North America and extended far offshore. This ended about 10,000 years ago with the transition to relative warming conditions in the Holocene that included several alternating intervals of warming and cooling. The last cooling interval was the Little Ice Age which started around 1350 AD and lasted about 500 hundred years. The present-day glaciers in Aialik are remnants of the Little Ice Age glacial advance.

Early humans followed the retreat of these glaciers and established settlements along the ice-free coastal fringe. Two prehistorical settlements in the Kenai Peninsula fjords are known, one at Northwestern Lagoon that was occupied between 1225 and 1750 AD, and another at McArthur Pass that was occupied between 250 and 1400 AD. Historical villages known by Russian fur traders included Yalik Village in Nuka Bay and an unnamed settlement at Verdant Cove in Aialik Bay. In 1793, a Russian fort was built at Voskresenskii near present-day Seward in Resurrection Bay. Outer coast indigenous residents were employed at Voskresenskii, traded furs there, and joined Russian-organized kayak fleets that were dispatched each year during the 1790s and early 1800s to hunt for sea otters along the Kenai Peninsula, Prince William Sound, and the mainland coast to the east. In 1794, Captain George Vancouver encountered one such flotilla that numbered over 400 men. Early Russian fur traders imposed a policy of universal service for the Alutiiq people where half of the male population between ages 18 and 50 could be taken for sea otter hunting for up to three years, but in reality, most able-bodied men, women, and children were required to hunt, fish, trap, harvest birds, prepare food, make clothing, or tan skins for company use. However, as Russian Orthodox missionaries arrived in the early 1800s and witnessed the plight and hardships of the Alutiiq, changes were made, and by 1844, labor documents referred to the outer Kenai Alutiiq as semi-dependent, meaning that the Russian-American Company had little or no actual control over their lives. In this situation, hunters were not subject to impressments but instead received payment for their furs in tobacco, beads, iron, copper, and other imported trade goods. Archaeologists excavated the Aialik settlement and found a midden mound and a cluster of seven house depressions, four cache pits, and two above-ground sod wall features indicating that the settlement was occupied by a group of 40 or more people in a combination of above-ground summer houses with sod walls, and semi-subterranean winter houses. It was apparently not occupied for more than a few years and may have been established as an early response to the Russian fort and trading center in neighboring Resurrection Bay, before resettling closer to the trading post.

The Aialik Glacier reaches tidewater at the extreme head of Aialik Bay. Evidence of more advanced positions of the glacier terminus that were occupied centuries ago are indicated by terminal moraine shoals, or sills, with depths of only 30 feet (9 m) stretching across Aialik Bay adjacent to Pederson Lagoon about 5 miles (8 km) south of the current terminus position. The glacial front is an ice cliff about 200 feet (61 m) high that is constantly discharging ice with activity peaking during the summer months. The glacier is retreating but much slower than others in Kenai Fjords. This is because the area of snow accumulation is much larger than the area of ice ablation. Aialik Glacier has a total area of about 17,297 acres (7,000 ha), with an accumulation area of 15,321 acres (6,200 ha), an ablation area of 1,977 acres (800 ha). The width of its terminus is 0.4 miles (0.6 km). In 1909, Ulysses S. Grant and Daniel F. Higgins photographed the terminus of Aialik Glacier and wrote a detailed description. Grant and Higgins stated that the glacier may have retreated as much as 1,312 feet (400 m) in the decade before 1909. Between 1950 and 1964, the glacier retreated about 984 feet (300 m) and between 1964 and the 1990s it retreated another 787 feet (240 m). The retreat of the glaciers in Kenai Fjords has exposed a coastline that is generally rocky and precipitous with many deep-water fjords. These conditions are highly attractive to harbor seal populations, and seals are particularly drawn to areas near calving tidewater glaciers for hauling out on floating ice. The availability of floating ice is influenced by fjord and glacier morphology, calving rates, currents, weather, water temperatures, and season. Ice tends to be most abundant in spring and diminishes in abundance as the summer progresses. Unlike terrestrial habitats, ice substrates are not flooded by tides and ice provides multiple haulout access points, allowing seals to aggregate in groups to benefit from group vigilance while reducing substrate-forced contact and crowding. Ice calved from Aialik Glacier circulates around Squab Island, about 1.2 miles (2 km) east of the terminus, and generally remains north of the sill at Pederson Lagoon. There are high densities of harbor seals in Kenai Fjords and several hundred living in Aialik Bay, however, the volume of floating glacier ice is being reduced by climate change and with ecological consequences. The number of harbor seals using glacial ice adjacent to Aialik Glacier declined by 93% from 1979 to 2009. Read more here and here. Explore more of Aialik Bay here:

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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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