It is possible to establish the relative order of events in some rocks. The underlying principle is that the probability of an individual radioactive atom breaking down (to create a daughter atom) is constant.
This is called stratigraphy and is most commonly used for sedimentary layers, laid down successively on top of one another. Different radioactive decay systems have different probabilities and these are expressed as their DECAY CONSTANT. potassium 40 goes to argon 40) and its unique decay constant, the number of daughter atoms created depends on the amount of time and the original number of parent atoms. In practice the determination of ages uses ratios between different isotopes, measured with great precision in modern mass spectrometers.
This challenge is mainly headed by Creationism which teaches a young-earth (YE) theory.
A young earth is considered to be typically just 6,000 years old since this fits the creation account and some dating deductions from Genesis.
And OE Christians (theistic evolutionists) see no problem with this dating whilst still accepting biblical creation, see Radiometric Dating - A Christian Perspective.
This is the crucial point: it is claimed by some that an old earth supports evolutionary theory and by implication removes the need for biblical creation.
We can use the leaky nature of rocks and minerals to isotopic diffusion to estimate the cooling history of rocks - which is very important in tracking the passage of rocks to the surface as their overburden is eroded.
And it is interesting to note that a 'herbivore existence' and the emphasis on 'no harm' re-appears during the Millennium, when the lion eats straw rather than kills for food (Isa 65.25).The concerns about these dating methods were exactly the same that creationists continue to raise - presence of the daughter element at the time the rock was formed and possible loss / gain of either the parent or daughter element at some point in the history of the rock.For this reason, the tests were designed to account for those possibilities.If we can establish Adam as a real man, then the biblical genealogies may give a good idea of the age of the earth.A literal interpretation of Genesis suggests that all living land creatures, including man, were created as herbivores rather than carnivores (Gen 1.29,30).