Dating tree cores
Over time, a few decades, the layers of snow compact under their own weight and become ice.
By drilling through that ice, and recovering cylinders of it, it is possible to reconstruct records of temperature and of atmospheric gases for periods of hundreds of thousands of years.
Whilst the Antarctic is a continent, the only major area of land in the Arctic covered with snow is Greenland.
There have been several ice cores drilled in Greenland but these core do not go as deep as those in the Antarctic.
The deepest ice, and therefore the ice with the longest record, is found in Antarctica.
Indeed, dating information is sometimes given for the “ice age” and “gas age”.Technologically the recovery of ice cores and their analysis is an amazing feat.Firstly as engineering: drilling thousands of metres in sub-zero temperatures, retrieving the cores and transporting them for analysis is a major feat.Thera is located in the Aegean Sea, and the effects of the eruption would have had catastrophic effects on the entire Eastern Mediterranean region.
The town of Akrotiri, located on the island itself, was buried under metres of volcanic ash, preserving the town in much the same way as Pompeii was preserved by Vesuvius (although the residents of Akrotiri had the forewarning of seismic tremors and evacuated prior to the eruption, for no evidence of bodies has yet been found there, unlike at Pompeii).Figure 6 shows the temperature for both the EPICA and the Vostok sites, which indicated that the temperature records are in good agreement for most of the time.