Method of carbon 14 dating
We will deal with carbon dating first and then with the other dating methods.
Carbon has unique properties that are essential for life on Earth.
Overall, the energy of the Earth's magnetic field has been decreasing, so more C is being produced now than in the past.
This will make old things look older than they really are.
This also has to be corrected for. Second, the ratio of C in the atmosphere at that time to be estimated, and so partial calibration of the “clock” is possible.
The flood buried a huge amount of carbon, which became coal, oil, etc., lowering the total C ratio in plants/animals/the atmosphere before the flood had to be lower than what it is now.
However, even with such historical calibration, archaeologists do not regard C produced and therefore dating the system.
The amount of cosmic rays reaching the Earth varies with the sun's activity, and with the Earth's passage through magnetic clouds as the solar system travels around the Milky Way galaxy.
These techniques, unlike carbon dating, mostly use the relative concentrations of parent and daughter products in radioactive decay chains.
For example, potassium-40 decays to argon-40; uranium-238 decays to lead-206 via other elements like radium; uranium-235 decays to lead-207; rubidium-87 decays to strontium-87; etc.It cannot be used to date volcanic rocks, for example.