Dating of rocks and geologic events - How Old is the Earth: Radiometric Dating - TalkOrigins Archive


Consider the dating of a piece of wood. As long as the tree lives, it absorbs carbon from the atmosphere in the form of carbon dioxide, both C-12 and C-14. Once the tree dies, it ceases to take in new carbon, and any C-14 present begins to decay. The changing ratio of C-12 to C-14 indicates the length of time since the tree stopped absorbing carbon, ., the time of its death.

Radiometric dating methods estimate the age of rocks using calculations based on the decay rates of radioactive elements such as uranium, strontium, and potassium. On the surface, radiometric dating methods appear to give powerful support to the statement that life has existed on the earth for hundreds of millions, even billions, of years. We are told that these methods are accurate to a few percent, and that there are many different methods. We are told that of all the radiometric dates that are measured, only a few percent are anomalous. This gives us the impression that all but a small percentage of the dates computed by radiometric methods agree with the assumed ages of the rocks in which they are found, and that all of these various methods almost always give ages that agree with each other to within a few percentage points. Since there doesn't seem to be any systematic error that could cause so many methods to agree with each other so often, it seems that there is no other rational conclusion than to accept these dates as accurate.

Contents. Introduction; Changing Estimates of the Age of the Earth; Chronology of Writings; History of Radiometric Dating ; References; Acknowledgements; Introduction


Dating of rocks and geologic events

Dating of rocks and geologic events