Extinct radionuclides were generated by various processes in the early Solar system, and became part of the composition of meteorites and protoplanets.
Notable isotopes with shorter lives still being produced on Earth include: Radioisotopes with half-lives shorter than one million years are also produced: for example, carbon-14 by cosmic ray production in the atmosphere (half-life 5730 years).
[4] Their usefulness derives from a few factors such as the fact that their short half-lives provide high chronological resolution and the chemical mobility of various elements can date unique geological processes such as igneous fractionation and surface weathering.
Compounding this problem is the increasing contribution that high-energy cosmic rays have on already minute amounts of daughter isotopes formed from the extinct nuclides.
Distinguishing the source and abundance of these effects is critical to obtaining accurate ages from extinct nuclides.