Absolute dating radiocarbon dating. The development of accelerator mass spectrometry (AMS) dating, which allows a date to be obtained from a very small sample, has been very useful in this regard. Other radiometric dating techniques are available for earlier periods. One of the most widely used is potassium–argon dating (K–Ar dating). Potassium-40 is a radioactive isotope of potassium that decays into argon-40. The half-life of potassium-40 is 1.3 billion years, far longer than that of carbon-14, allowing much older samples to be dated. Potassium is common in rocks and minerals, allowing many samples of geochronological or archeological interest to be dated. Argon,
Willis Resilience Expedition of the deposition rate of Tritium, a radioactive isotope of hydrogen, across Antarctica. The relatively short half-life of Tritium means it can be used to date snow and ice up to around 150 years old. The data can then be used to better understand the global water cycle, which is intrinsically linked to changes in climate. This will be the first large-scale study of Tritium in Antarctica since Tritium returned to normal levels following the spike caused by thermonuclear tests in the 1960s. The samples will be sent to GNS Science, a New Zealand Crown Research Institute, for analysis. Once