In a paper published this week in Science, geochemist Roland Mundil of the Berkeley Geochronology Center (BGC) and his colleagues at BGC and UC Berkeley report that uranium/lead (U/Pb) dating can be extremely accurate - to within 250,000 years - but only if the zircons from volcanic ash used in the analysis are

What is the half life of uranium lead dating?

4.5 billion years RADIOMETRIC TIME SCALEParent IsotopeStable Daughter ProductCurrently Accepted Half-Life ValuesUranium-238Lead-2064.5 billion yearsUranium-235Lead-207704 million yearsThorium-232Lead-20814.0 billion yearsRubidium-87Strontium-8748.8 billion years2 more rows•13 Jun 2001