Radiometric dating of fossils

The older of the two dating methods, the geologic timescale, is actually a circular argument and is therefore considered by many scholars to be weak.

Scientists can't tell whether the clock ran down a few days or millions of years ago.The more parent isotopes there are -- and the fewer daughter isotopes -- the younger the sample.The half-life of the isotope being measured determines how useful it is at dating very old samples.Only hard parts, like bones and teeth, can become fossils.But for some people, the discovery raised a different question.

Scientists generally agree that the answer to the riddle of the age of the earth is carefully concealed within the earth's crust.