Changes

::::: Radiometric dating involves measuring the ratio of parent and daughter elements, and calculating from that ratio how long it has been decaying.  Uranium decays through a number of steps to eventually become lead, so one way of dating objects is to measure the relative amounts of uranium and lead.  However, one of the intermediate elements is thorium, so you can also measure the relative amounts of uranium and thorium.  Therefore if the relative amounts of two isotopes of uranium, thorium, and two isotopes of lead are measured, then one should be able to determine the date from three calculations: two from the different uranium-lead ratios and one from the uranium-thorium ratio.  You are arguing that because the two uranium-lead figures agree, the date is likely to be accurate.  But the link I provided argues that because the thorium figure was zero, this indicates that there is a problem with the sample (perhaps leaching) that makes the uranium-lead date unreliable.

::::: Radiometric dating involves measuring the ratio of parent and daughter elements, and calculating from that ratio how long it has been decaying.  Uranium decays through a number of steps to eventually become lead, so one way of dating objects is to measure the relative amounts of uranium and lead.  However, one of the intermediate elements is thorium, so you can also measure the relative amounts of uranium and thorium.  Therefore if the relative amounts of two isotopes of uranium, thorium, and two isotopes of lead are measured, then one should be able to determine the date from three calculations: two from the different uranium-lead ratios and one from the uranium-thorium ratio.  You are arguing that because the two uranium-lead figures agree, the date is likely to be accurate.  But the link I provided argues that because the thorium figure was zero, this indicates that there is a problem with the sample (perhaps leaching) that makes the uranium-lead date unreliable.

::::: [[User:Philip J. Rayment|Philip J. Rayment]] 08:06, 21 May 2008 (EDT)

::::: [[User:Philip J. Rayment|Philip J. Rayment]] 08:06, 21 May 2008 (EDT)

::::But what about the ²⁰⁷/Pb²⁰⁶Pb dating? --[[User:MichaelK|MichaelK]] 18:01, 21 May 2008 (EDT)

::::But what about the ²⁰⁷Pb/²⁰⁶Pb dating? --[[User:MichaelK|MichaelK]] 18:01, 21 May 2008 (EDT)