As like in the circular logic used by the evolutionist? Dating the fossils by the layer they are found in and dating the layers by the fossils they contain.
"Dating the fossils by the layer they are found in and dating the layers by the fossils they contain."
Do you have a source for this contention?
Now I know that you get all your information from creationist sites. That is not how fossils, nor strata are dated. Geologists have used "index fossils" to roughly date strata, but fine-tuned dating usually involves one or more radiometric processes (which are used to double check one another -- go ahead and claim that decay rates were different in the past; if that were the case different isotopes would give wildly conflicting dates).
Again it's not circular. But it's also incorrect to associate the applicable methods with evolutionists. They were invented by and used by creationists many decades before Darwin published his ideas.