Soviet ice drilling projects in Antarctica include decades of work at Vostok Station, with the deepest core reaching 3769 m.
The lowest layer of a glacier, called basal ice, is frequently formed of subglacial meltwater that has refrozen.
According to Heiltsuk Nation’s oral traditions, stories of ancient coastal villages have been passed down for generations.
William Housty, from the Heiltsuk Nation, said: “To think about how these stories survived all of that, only to be supported by this archaeological evidence is just amazing”.
At Summit Camp in Greenland, the depth is 77 m and the ice is 230 years old; at Dome C in Antarctica the depth is 95 m and the age 2500 years.
As further layers build up, the pressure increases, and at about 1500 m the crystal structure of the ice changes from hexagonal to cubic, allowing air molecules to move into the cubic crystals and form a clathrate.