Isotope studies show that the Vostok ice core consists of ice refrozen from
Lake Vostok water, from 3539 meters below the surface of the Antarctic ice
sheet to its bottom at about 3750 meters. Additional evidence comes from t
he total gas content, crystal size, and electrical conductivity of the ice.
The Vostok site is a likely place for water freezing at the Lake-ice inter
face, because this interface occurs at a higher Level here than anywhere el
se above the Lake. Isotopic data suggest that subglacial Lake Vostok is an
open system with an efficient circulation of water that was formed during p
eriods that were slightly warmer than those of the past 420,000 years. Lake
ice recovered by deep drilling is of interest for preliminary investigatio
ns of Lake chemistry and bedrock properties and for the search for indigeno
us lake microorganisms. This latter aspect is of potential importance for t
he exploration of icy planets and moons.