How do scientists use radiometric dating
by Tas Walker A geologist works out the relative age of a rock by carefully studying where the rock is found in the field.The field relationships, as they are called, are of primary importance and all radiometric dates are evaluated against them.They consist of measuring the amount of radioactive (mother) element and comparing it to the amount of stable (daughter) element. Uranium is radioactive, which means it is in the process of changing from an unstable element into a stable one. And after 9 billion years there would be 75% lead and 25% uranium, and so on. (an) episode of drastically accelerated decay has ... When the crystal is looked at under a microscope, these discolourations appear as dark ringshence the name "pleochroic halo".Few people realize it but all radiometric dating methods require making at least three assumptions. Now the magnitude of the radius of a pleochroic halo in a particular mineral depends on the amount of energy that the alpha particle has ... depends on the half-life of the particular decay responsible for this alpha particle emission.
Radiometric dating is self-checking, because the data (after certain preliminary calculations are made) are fitted to a straight line (an "isochron") by means of standard linear regression methods of statistics.Dating is not necessary to demonstrate that evolution is a fact.Chronological sequence is all that is really required.Clearly, Sedimentary Rocks A were deposited and deformed before the Volcanic Dyke intruded them.These were then eroded and Sedimentary Rocks B were deposited.