Sif Island is an island in

Pine Island Bay The Amundsen Sea, an arm of the Southern Ocean off Marie Byrd Land in western Antarctica, lies between Cape Flying Fish (the northwestern tip of Thurston Island) to the east and Cape Dart on Siple Island to the west. Cape Flying Fish marks the ...

of the Amundsen Sea, in

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest cont ...

. It is long and consists of

potassium feldspar Potassium feldspar refers to a number of minerals in the feldspar group, and containing potassium: *Orthoclase ( endmember formula K Al Si3 O8), an important tectosilicate mineral that forms igneous rock *Microcline, chemically the same as orthocla ...

granite Granite () is a coarse-grained ( phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies under ...

, mostly covered in ice. It was discovered in February 2020 after the

Pine Island Glacier Pine Island Glacier (PIG) is a large ice stream, and the fastest melting glacier in Antarctica, responsible for about 25% of Antarctica's ice loss. The glacier ice streams flow west-northwest along the south side of the Hudson Mountains into Pine ...

melted away from around it, and is named after

Sif In Norse mythology, Sif (Old Norse: ) is a golden-haired goddess associated with earth. Sif is attested in the ''Poetic Edda'', compiled in the 13th century from earlier traditional sources, and the ''Prose Edda'', written in the 13th century ...

, an

Æsir The Æsir (Old Norse: ) are the gods of the principal pantheon in Norse religion. They include Odin, Frigg, Höðr, Thor, and Baldr. The second Norse pantheon is the Vanir. In Norse mythology, the two pantheons wage war against each other, ...

goddess associated with the

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

in Norse mythology. It is plausible that the island emerged as a result of

post-glacial rebound Post-glacial rebound (also called isostatic rebound or crustal rebound) is the rise of land masses after the removal of the huge weight of ice sheets during the last glacial period, which had caused isostatic depression. Post-glacial rebound ...

, a process in which retreating glaciers relieve pressure on the ground, causing it to rise.

History

The steady retreat of the

and

Thwaites Glacier Thwaites Glacier, nicknamed the Doomsday Glacier, is an unusually broad and vast Antarctic glacier flowing into Pine Island Bay, part of the Amundsen Sea, east of Mount Murphy, on the Walgreen Coast of Marie Byrd Land. Its surface speeds exceed ...

since the early 2010s had left Sif Island separate from glacier ice in the Pine Island Bay, completely detaching in 2014 as seen in

Landsat The Landsat program is the longest-running enterprise for acquisition of satellite imagery of Earth. It is a joint NASA / USGS program. On 23 July 1972, the Earth Resources Technology Satellite was launched. This was eventually renamed to La ...

satellite imagery. The island may now be undergoing post-glacial rebound. Sif Island was discovered in February 2020 by researchers with the Thwaites Glacier Offshore Research (THOR) project, aboard the '' Nathaniel B. Palmer'' research vessel. On February 11, 2020, marine geologist and crew member Julia Wellner announced the island's discovery via

Twitter Twitter is an online social media and social networking service owned and operated by American company Twitter, Inc., on which users post and interact with 280-character-long messages known as "tweets". Registered users can post, like, and ...

, stating that a crew member aboard the ship had spotted the rocky outcropping of granite, visible beneath a 'mushroom' of remnant ice. As ships rarely pass as far south as Sif Island, it is likely that the researchers aboard the ''Nathaniel B. Palmer'' are the first people to have seen the island and landed upon its granite bedrock. Despite the island being visible by satellite, its icy cap prevented it from being discovered earlier, as it blended in with the surrounding glacier. On February 23, photos of the researchers' first landing on the island were posted by Wellner on her Twitter account. She confirmed that the island is made of granite, covered with residual ice, and home to a few seals.

References

{{Antarctica Islands of Antarctica New islands Uninhabited islands