GEOL 1003 Chapter : Ch 3c Minimized
Document Summary
How old is the earth: early estimates based on 3 major arguments, salt in the ocean, assumed initial ocean was fresh, total sodium (na)/annual na = age of the ocean, 1899 - joly, irish physicist estimated. 137,195 0. 305m/1000 years: fossil bearing rocks >450 million years old, refuted - rates variable, unknown. Like light but with a very short wavelength. Geological processes affecting/resulting from isotopic decay: rate of decay is generally independent of external forces. Such as temperature and pressure: decay produces heat - drives earth processes. Isotopic dating - absolute dates: based on parent/daughter ratio when the decay is known, requires a closed system. Neutron changes to a proton in the nucleus (2) daughter atomic number is 1 higher (3) daughter atomic weight is the same: electron capture (1) parent nucleus gains a beta particle. Proton changes to a neutron in the nucleus (2) daughter atomic number is 1 lower (3) daughter atomic weight is the same.
