Radiometric dating assumptions ireland dating site 208
The ages assigned to various rock strata bearing distinctive types of fossils show extraordinary agreement. We have already discussed statements akin to Morris's first and second assumptions.
The many independent computations of the age of the earth during the last three decades almost invariably yield a figure between 4.2 and 4.8 billion years. As will become clear shortly, the status of the third is a little different.
Minerals can be tested for their capacity to absorb extra argon under experimental conditions designed to resemble their natural environment, and geologists can screen out, in this way, minerals that are liable to give erroneous results.
In the second case, the existence of two separate decay processes provides a check on the assumption that the system has not been contaminated.
For if extra daughter element were added, then we should arrive at too large a figure for the amount of the parent element that has decayed, and thus produce too high a value for the age of the rock.) Geologists are not unaware of these assumptions, and they take great pains to construct ways of cross-checking them.
Argon is an inert gas, so that it does not occur in chemical compounds in original rocks.
Obviously just the opposite holds when the ratio of lead-206 to lead-207 is too small.
In both the examples I have described, there are ways of checking that such intrusions have not occurred.
A second, independent, astronomical method is to use standard techniques to measure some parameters of stars (mass, luminosity, compositor, and surface temperature), from which a well-confirmed theory of the life histories of stars enables physicists to compute their. Finally, considerations of radioactive decay make it possible to calculate the time at which certain heavy elements were formed.