While these values do not compute an age for the Earth, they do establish a lower limit (the Earth must be at least as old as any formation on it).This lower limit is at least concordant with the independently derived figure of 4.55 billion years for the Earth's actual age.For example: Also note that the meteorite ages (both when dated mainly by Rb-Sr dating in groups, and by multiple means individually) are in exact agreement with the solar system "model lead age" produced earlier.
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.
) and they are historically the ones posted to talk.origins more than any others.
The young-Earth argument goes something like this: helium-4 is created by radioactive decay (alpha particles are helium nuclei) and is constantly added to the atmosphere.
Helium is not light enough to escape the Earth's gravity (unlike hydrogen), and it will therefore accumulate over time.
The current level of helium in the atmosphere would accumulate in less than two hundred thousand years, therefore the Earth is young.
The higher the uranium-to-lead ratio of a rock, the more the Pb-206/Pb-204 and Pb-207/Pb-204 values will change with time.
If the source of the solar system was also uniformly distributed with respect to uranium isotope ratios, then the data points will always fall on a single line.
Over time, the amounts of Pb-206 and Pb-207 will change in some samples, as these isotopes are decay end-products of uranium decay (U-238 decays to Pb-206, and U-235 decays to Pb-207).
This causes the data points to separate from each other.
A plot is constructed of Pb-206/Pb-204 versus Pb-207/Pb-204.