It's assumed that the clock was set to zero when the study material was formed.
This requires that only the parent isotope be initially present or that the amount of daughter isotope present at the beginning is known so that it can be subtracted.
Many examples from literature show that the zero-reset assumption is not always valid.
Volcanic ejecta of Mount Rangitoto (Auckland, New Zealand) was found to have a potassium-40 age of 485,000 years, yet trees buried within the volcanic material were dated with the carbon-14 method to be less than 300 years old.
Some scientists argue that the magnetic field of the earth has declined over time.
c) Atmospheric carbon forms just 0.0005% of the current carbon reservoir—99.66% of the earth's carbon exists in limestone, 0.31% in oil and gas, and 0.02% in coal.
A rock sample from Nigeria was dated at 95 million years by the potassium-argon method, 750 million years by the uranium-helium method, and less than 30 million years by the fission-track method.
If the clock is not set to zero when a deposit forms, then there can be no starting point from which to calculate the age of a deposit.We could put forward the following counter arguments to the constancy of these assumptions: a) The constancy of cosmic ray bombardment might be questioned.The current high rate of entry might be a consequence of a disturbed post-Flood environment that altered the .People wonder how millions of years could be squeezed into the biblical account of history. Christians, by definition, take the statements of Jesus Christ seriously.Clearly, such huge time periods cannot be fitted into the Bible without compromising what the Bible says about the goodness of God and the origin of sin, death and suffering—the reason Jesus came into the world (See Six Days? He said, This only makes sense with a time-line beginning with the creation week thousands of years ago.A further example from a lava flow off the coast of Hawaii shows similar discrepancies.