Hiawatha Glacier
Hiawatha Glacier is a glacier in northwest Greenland, with its terminus in Inglefield Land. It was mapped in 1922 by Lauge Koch, who noted that the glacier tongue extended into Lake Alida (near Foulk Fjord). Hiawatha Glacier attracted attention in 2018 because of the discovery of a crater beneath the surface of the ice sheet in the area. A publication noted in 1952 that Hiawatha Glacier had been retreating since 1920. Possible impact structure In November 2018, a study revealed the existence of a large () circular depression beneath Greenland's ice sheet in the Hiawatha Glacier region—up to a kilometre below the surface of the ice. The bedrock within the region of this structure consists of 1.985 to 1.740 billion year old Paleoproterozoic felsic igneous rocks and paragneiss. From an interpretation of the crystalline nature of the underlying rock, together with chemical analysis of sediment washed from the crater, the impactor was argued to be a metallic asteroid with a diameter in the order of . A volume of approximately of rock would have been either vaporized or melted. Such an impact would have continued to melt ice flowing into the crater for an as-of-yet undetermined period post-impact. If an impact origin for the crater is confirmed, it would be one of the twenty-five largest known impact craters on Earth. A 2022 study using argon–argon dating combined with uranium–lead dating of shocked zircon crystals in impact melt rocks found in outwash less than 10 km downstream of the glacier yielded an age of 57.99 ± 0.54 million years ago, during the late Paleocene. This put an end to speculation by advocates of the controversial Younger Dryas impact hypothesis. that it was formed by an impact as recently as ~12,800 years ago. See also List of possible impact structures on Earth Bølling-Allerød warming Operation IceBridge References External links International Team, NASA Make Unexpected Discovery Under Greenland Ice NASA/Video Massive crater under Greenland's ice points to climate-altering impact in the time of humans Video Discovering a massive meteorite crater Docu/Video Impact craters of Greenland Glaciers of Greenland Younger Dryas impact hypothesis