‘Scratching the surface with cosmogenic isotopes’ explains spallation—when a high energy cosmic ray particle removes several nucleons from an atom. Spallation produces 10Be from 16O in the atmosphere and rock surfaces, while spallation of silicon produces another cosmogenic isotope, 26Al. Cosmogenic isotope production is about four times greater at the poles than at the equator and is also greater at higher altitudes. To calculate a cosmogenic isotope exposure age, the latitude and altitude at which the sample was exposed needs to be known. Using ‘exposure’ and ‘burial’ methodologies, cosmogenic isotopes can be used to address various scientific problems such as recreating the seismic histories of tectonically active areas.