sentences:  Drilling of the core was deliberately halted roughly  above the suspected boundary between the ice sheet and the liquid waters of the lake.This was to prevent contamination of the lake with the 60-ton column of Freon and kerosene used to prevent the borehole from collapsing and freezing over.From this core, specifically from ice that is thought to have formed from lake water freezing onto the base of the ice sheet, extremophile microbes were found, suggesting that the lake water supports life.