Dating antarctic ice cores dating ture til polen
Since the ice forms from the incremental buildup of annual layers of snow, lower layers are older than upper, and an ice core contains ice formed over a range of years.
Cores are recovered by drilling with hand augers (for shallow holes) or powered drills; the deepest cores recovered reach depths of over two miles, and can contain ice up to 800,000 years old.
Greenland ice cores contain layers of wind-blown dust that correlate with cold, dry periods in the past, when cold deserts were scoured by wind.
Radioactive elements, either of natural origin or created by nuclear testing, can be used to date the layers of ice in the cores.
As the snow is deposited on top of the ice sheet each year, it traps different chemicals and impurities which are dissolved in the ice.
These layers can be counted only so far down because the weight of the ice compresses the layers more and more the deeper they are in the ice.Because of the low temperatures, however, there is little or no melt.Thus the snow has accumulated year after year for thousands of years and, with time, is compressed to ice to form the Antarctic ice sheet.Approximately 98 per cent of the Antarctic continent is covered by the ice sheet which is on average about 2,500 metres thick and, at it's deepest location, 4,700 metres thick.It is due to this thick ice mass that Antarctica is, on average, the highest continent.