Using radiometric techniques, the oldest dated minerals 4. Calculating radiocarbon ages also requires the value of the half-life for 14 C. But YE scientists point out some anomalies in relation to C and a very old earth. And for radiometric dating it means that the decay constant of the parent has not changed over earth's history. While uranium is water-soluble, thorium and protactinium are not, and so they are selectively precipitated into ocean-floor sedimentsfrom which their ratios are measured. Dating methods based on extinct radionuclides can also be calibrated with the U-Pb method to give absolute ages. So whilst isochron dating can give a straight line, the slope may have no significance [Vardiman et al].
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The Age of the Earth
Most people accept the current old-earth OE age estimate of around 4. Science Radiometric datingradioactive dating or radioisotope dating is a technique used to date materials such as rocks or carbonin which trace radioactive impurities were selectively incorporated when they were formed.