Radiometric dating of rock strata
Note that young-Earthers cannot accuse us of selective use of data -- the above table includes a significant fraction of all meteorites on which isotope dating has been attempted. 286) , less than 100 meteorites have been subjected to isotope dating, and of those about 70 yield ages with low analytical error.
Further, the oldest age determinations of individual meteorites generally give concordant ages by multiple radiometric means, or multiple tests across different samples.
For example, Henry Morris says: He lead to similar results, i.e., a rate virtually identical to the estimated production flux.
Another possible escape mechanism is direct interaction of the solar wind with the upper atmosphere during the short periods of lower magnetic-field intensity while the field is reversing.
The actual underlying assumption is that, if those requirements have not been met, there is no reason for the data points to fall on a line.
The resulting plot has data points for each of five meteorites that contain varying levels of uranium, a single data point for all meteorites that do not, and one (solid circle) data point for modern terrestrial sediments.
Helium is not light enough to escape the Earth's gravity (unlike hydrogen), and it will therefore accumulate over time.
In order to obtain a young age from their calculations, young-Earthers handwave away mechanisms by which helium can escape.
A plot is constructed of Pb-206/Pb-204 versus Pb-207/Pb-204.
If the solar system formed from a common pool of matter, which was uniformly distributed in terms of Pb isotope ratios, then the initial plots for all objects from that pool of matter would fall on a single point.
And from the slope of the line we can compute the amount of time which has passed since the pool of matter became separated into individual objects.
See the Isochron Dating FAQ or Faure (1986, chapter 18) for technical detail.