The thickness of Antarctic ice is tough to measure because it is literally freezing on top and hard to reach at the bottom.
The underside of the thinnest sheets is estimated to be less than 200 metres (656 feet) from the surface. Where the ice is thickest, though, you would have to drill down more than ten times that distance to reach the base.
Scientists have long thought that Antarctic ice builds up largely through snow forming layers like those in sedimentary rocks. Recently, however, they have discovered that ice sheets might also grow through a process of water thawing and refreezing to the bottom.
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