Hi Ikester,

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Question: If all of the universe came from the same matter in the Big Bang, why does not all matter date back to that Big Bang? If age dating was 100% accurate, that all planets, and all matter would date the same age. But they don't do they?


Radiometric dating of igenous rock dates the time at which is cooled and crystallised. Cosmogenic dating dates the amount of exposure to cosmic rays that rock or ice has undergone, in effect dating the amount of time the surface has been exposed. Those are two I know off the top of my head. The uranium dating in the Grand Canyon discussions is also a way of doing this.

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A closer more likely event that shows age dating wrong. The moon is said to have formed from the earth from a meteor impact. So the moon is of the same matter as the earth, correct? Why the age difference?


Current theory is that a planet-sized object smashed into the earth very early in its history, during what we call the era of heavy bombardment. The fragments of the moon came together to form the moon billions of years ago. So it is more or less the same age of the earth, as radiometric dating of moon rocks tells us.

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Is there such a thing as cross contamination in age dating? Yes there is. What this means is that if a fossil, that dates a few thousand year old, is buried in a geological layer that dates a millions years old. Given time the layer will cross contaminate the fossil to date the same age as the layer does. This is why layers date the fossils, and fossils date the layers so well.


The radiometric dating methods of rocks are not used on fossils. If we are doubtful about the age of a fossil, and whether or not it has been found in situ (as opposed to having been washed there from elsewhere, for example), there are various methods that can be employed. It can be compared with index fossils present in the same rock. A fluorine analysis can also be done:

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When bones, teeth, or antlers are found at a site, fluorine analysis can be used to tell us whether or not the animals they were from actually lived at about the same time. This relative dating method is based on the fact that there are specific progressive chemical changes in skeletal remains that result from burial underground. As time passes, the organic components of bone (mostly fats and proteins) are lost primarily through bacterial action. Since these components contain nitrogen, there is a progressive loss of that element. At the same time, percolating ground water deposits trace amounts of fluorine and other elements, such as uranium, into the bone. As a result, the amount of fluorine progressively increases. If the bones of two animals are buried at the same time in the same site, they should have about the same amount of nitrogen and fluorine. If they do not, they most likely come from different eras, despite the fact that they were found in association with each other.


Again, these are just the ones I know off the top of my head. I am not a scientist and I'm sure there are others. If you have a specific example here that you would like to discuss, please let me know.