When a high-energy proton collides with an atom in the Earth’s atmosphere, it can break apart that atom to produce (still high-energy) secondary radiation in the form of neutrons, protons, and other subatomic particles.
Those particles continue traveling toward the Earth’s surface, likely colliding with additional atoms on the way.
| Using cosmogenic nuclides in glacial geology | Sampling strategies cosmogenic nuclide dating | Difficulties in cosmogenic nuclide dating | Calculating an exposure age | Further Reading | References | Comments | Cosmogenic nuclide dating can be used to determine rates of ice-sheet thinning and recession, the ages of moraines, and the age of glacially eroded bedrock surfaces.
Cosmogenic nuclide dating uses the interactions between cosmic rays and nuclides in glacially transported boulders or glacially eroded bedrock to provide age estimates for rock at the Earth’s surface.
This work was done in collaboration with Julie Libarkin at Ohio University.
Work continues with Doug Burbank at UCSB and Caltech graduate student Willy Amidon.
Surface exposure age dating requires intensive chemistry.
Our samples are now pre-treated at the University of Canterbury.
This is important for glacial geologists, as it means that surfaces that have had repeated glaciations with repeated periods of exposure to cosmic rays can still be dated, as long as they have had sufficient glacial erosion to remove any inherited signal.Super high energy particles—mostly protons— are produced by our Sun, supernovae, and probably other extraterrestrial sources.These particles continuously enter the Earth system at incredible rates and are often, but misleadingly, called cosmic rays.Different isotopes are used for different lengths of times.This long period of applicability is an added advantage of cosmogenic nuclide dating.