Thread: radiological dating question

i know that radiological dating is based on that one element decays into another over time, but how do we know that the object lying inside a specific rock has the same age as the rock?

When you say "object," do you mean a specific mineral within the rock? Or do you mean something else? If its the former, the mineral will crystallize when rock was last molten, so radiometrially dating the mineral gives us the point at time in which the rock went from a molten to solid state.

ok. so molten rocks do not decay?
i'm talking like for uranium decaying to lead.
how do you reset this timer?
afaik, no outside influences ave neutrons crashing into the atoms can cause atoms to split up?

ho hmm..
http://en.wikipedia.org/wiki/Fossil

Originally Posted by dejawolf

ok. so molten rocks do not decay?
i'm talking like for uranium decaying to lead.

Any radioactive elements present in the magma will decay at the same rate as those in the solid rock. The point is that in the solid rock we now fix the quantity of the parent element. The daughter element(s) can then be measured at any point after the rock/mineral solidify/crystalise to give us a measure of the elapsed time. This is the timer reset you refer to.

Could you explain what you were asking or stating with your wikipedia link?

The fossil richness in molten rock is probably improbably low.