Cosmogenic surface exposure dating
It is particularly useful in Antarctica, because of a number of factors: Cosmogenic nuclide dating is effective over short to long timescales (1,000-10,000,000 years), depending on which isotope you are dating.
Different isotopes are used for different lengths of times.
Cosmogenic nuclide dating can also be used in this context to understand past ice-sheet thicknesses and changes in subglacial thermal regime.
Sampling strategy is the most important factor in generating a reliable exposure age.
Cosmogenic nuclides are rare nuclides that form in surface rocks because of bombardment by high-energy cosmic rays.
Many mountains have on them, and are smoothed and eroded below the trimline, and more weathered with more evidence of periglaciation above the trimline.
Because cosmic rays become attenuated with depth through the rock, scientists are only interested in collecting the upper few centimetres of a rock’s surface.
Rock samples may be collected with a hammer and chisel or with a rock saw. One of the largest errors in cosmogenic nuclide dating comes from a poor sampling strategy.
Wherever we are on Earth, when we are outside, we are constantly bombarded by these cosmic rays.
When particular isotopes in rock crystals are bombarded by these energetic cosmic rays neutrons, a reaction results.