Cores and perforations

The presence of solid impurities and air bubbles trapped within the ice provide vital information about the chemical composition of the atmosphere and the temperature at the time of ice formation.It is of course essential that the ice should not have undergone melting processes, which would disperse the air bubbles: therefore, for these kinds of studies, one has to work on cold glaciers in polar regions. In some parts of the Earth, ice can be very old, like at the base of the great ice-sheets of Antarctica and Greenland, where ice can be older than 300,000 – 500,000 years. From the study of ice in these places it is therefore possible to reconstruct in detail the variations in temperature and in chemical composition of the atmosphere over a very long lapse of time, enabling us to gain access to a precious source of data regarding the climate in the past. For these studies drillings are carried out that extract long cylindrical ice samples which must not have any interruptions or missing parts from the surface up to the depth reached: in Antarctica, drilling reached a depth of over 2,000 m, as in Dome C (a project in which Italy participated) or in the Vostok perforation (Soviet), where the longest core, covering a time span of 420,000 years, was obtained.

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