A related method is ionium—thorium datingwhich measures the ratio of ionium thorium to thorium in ocean sediment. Another minor source of naturally occurring radioactive nuclides are cosmogenic nuclidesthat are formed by cosmic ray bombardment of material in the Earth's atmosphere or crust. Learn More in these related Britannica articles: Isotopes are unstable forms of elements. Become a Member Already a member?
Isotopes of elements heavier than boron were not produced at all in the Big Bang, and these first five elements do not have any long-lived radioisotopes.
Clocks in the Rocks
Asymptotes, Domain, and Range Vector Spaces: Thus, as an event marker of s water in soil and ground water, 36 Cl is also useful for dating waters less than 50 years before the present. The methods work because radioactive elements are unstable, and they are always trying to move to a more stable state. Prentice Hall Earth Science: Older ages in the neighborhood of 4. This converts the only stable isotope of iodine I into Xe via neutron capture followed by beta decay of I. Scientists call this behavior radioactivity.