Radioactive decay and radiometric dating accomodating multiple learning styles
For example lavas dated by K-Ar that are historic in age, usually show 1 to 2 my old ages due to trapped Ar.Such trapped Ar is not problematical when the age of the rock is in hundreds of millions of years.Prior to 1905 the best and most accepted age of the Earth was that proposed by Lord Kelvin based on the amount of time necessary for the Earth to cool to its present temperature from a completely liquid state.Although we now recognize lots of problems with that calculation, the age of 25 my was accepted by most physicists, but considered too short by most geologists. Recognition that radioactive decay of atoms occurs in the Earth was important in two respects: Principles of Radiometric Dating Radioactive decay is described in terms of the probability that a constituent particle of the nucleus of an atom will escape through the potential (Energy) barrier which bonds them to the nucleus.Since the exact rate at which uranium decays into lead is known, the current ratio of lead to uranium in a sample of the mineral can be used to reliably determine its age.The method relies on two separate decay chains, the uranium series from Pb) leads to multiple dating techniques within the overall U–Pb system.
Other minerals that also show these properties, but are less commonly used in radiometric dating are Apatite and sphene.
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