The drilling has been performed in a location where a subglacial lake some 250 X 50 Km in area, exists under 3800 meters of ice.
The bottom 210 meters of ice is not of meteoric origin, but results from accretion of individual frazil ice crystals born in the
water column, due to peculiar circulation patterns in the lake water. These are similar to those existing below ice shelves at the
ice sheet margin.