The primordial nuclide beryllium-9, the only stable beryllium isotope, is an example of this type of nuclide.
In contrast, even though the radioactive isotopes beryllium-7 and beryllium-10 fall into this series of three light elements (lithium, beryllium, boron) formed mostly by cosmic ray spallation nucleosynthesis, both of these nuclides have half lives too short for them to have been formed before the formation of the Solar System, and thus they cannot be primordial nuclides.
Surface exposure dating is a collection of geochronological techniques for estimating the length of time that a rock has been exposed at or near Earth's surface.
Surface exposure dating is used to date glacial advances and retreats, erosion history, lava flows, meteorite impacts, rock slides, fault scarps, cave development, and other geological events.
It is most useful for rocks which have been exposed for between 10 years and 30,000,000 years.