Geological dating radioactive elements Skypesexchat deutsche kontackte
Another line of evidence is based on the present-day abundances of the various isotopes of lead found in the Earth's crust. Three of these isotopes (lead 206, 207, 208) result from radioactive decay of isotopes of thorium and uranium.
This means that as radioactive parent elements decay, they and their daughters are trapped together inside the crystal.The discovery gave scientists a tool for dating rocks that contain radioactive elements.Many elements have naturally occurring isotopes, varieties of the element that have different numbers of neutrons in the nucleus.Once scientists have determined the parent-daughter ratio, they can use this measurement along with half-life of the parent to calculate the age of a rock containing the radioactive isotope.Radiometric dating has shown that very old rocks--3.5 billion years or older--occur on all the continents.
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If, however, the rock is subjected to intense heat or pressure, some of the parent or daughter isotopes may be driven off.