If this does not completely prove that radiometric dating is correct, it does at least show that barring a wildly improbable coincidence there is at least a one-to-one relationship between the dates produced by radiometric methods and the true dates, and so it must be taken as an argument in favor of these methods.
It is possible to test radiocarbon dating by using it to put a date on historical artifacts of known date, and to show that it is usually very accurate. It has also been possible to test Ar-Ar dating against the historical record, since it is sufficiently sensitive to date rocks formed since the inception of the historical record. For example, Ar-Ar dating has been used to give an accurate date for the eruption of Vesuvius in 79 A.
D, as recorded by Roman historians at the time. See Lanphere et al. Because varves contain organic material, it is possible to compare the dates from varves with the dates produced by radiocarbon dating , and see that they are in good agreement. We also see close agreement between dendrochronology and uncalibrated radiocarbon dates. I specify uncalibrated dates because as radiocarbon dating is calibrated against dendrochronology , the agreement of calibrated radiocarbon dates with dendrochronology is inevitable.
Now, each of these three methods relies on a different underlying physical process: We can hardly suppose that there is some single mechanism which would interfere with all three of these very different processes in such a way as to leave the dates derived from them still concordant. But it is equally far-fetched to imagine that three different mechanisms interfered with the three processes in such a way as to leave the dates concordant ; that would require either a preposterous coincidence, or for natural processes to be actually conspiring to deceive us: Now, preposterous things do happen occasionally.
But in this case there is a perfectly reasonable and straightforward explanation for why the dates are concordant , namely that they are correct.
Similar remarks may be made about the agreement between radiometric dating of rocks, sclerochronology , and dating by rhythmites. Are we to believe that one single mechanism interfered with the decay of radioactive isotopes , the secretion of calcium carbonate by molluscs, and the action of the tide? But are we instead to believe that three separate mechanisms interfered with these processes in such a way as to leave all the dates concordant? That would be equally absurd. The straightforward explanation for the concordance of the dates is that they are in fact correct.
Consider the following analogy: Skeptical of the clockmaker's claim, we subject the clocks to shock: Throughout this process, they all go on showing exactly the same time. Is it plausible that we have damaged their very different internal mechanisms in such a way that they are all running fast or slow but still in perfect synchrony? Or is it more likely that they are synchronized because nothing that's happened to them has affected their working? Relative dating by definition does not produce actual dates, but it does allow us to put an order on the rocks, and so if absolute dating is to be trusted, it should agree with this order, telling us, for example, that Ordovician rocks are older than Triassic rocks; and it does.
It is hard to see this as a coincidence; it is equally hard to think of some alternate explanation of why we can correlate isotope ratios or sclerochronological data with the relative order of rocks as deduced from stratigraphic methods — other than the straightforward explanation that absolute dating is producing the right dates. In our discussion of radiometric dating , we have seen that many, indeed most, radiometric methods are self-checking. So in the U-Pb method , we check that the two uranium isotopes produce concordant dates.
In the Ar-Ar method , we check that step heating yields the same date at every step.
These precautions allow us to throw out most data that have been produced by confounding factors such as atmospheric contamination, weathering , hydrothermal events, metamorphism , metasomatism , etc. It is, as we have explained, possible for the occasional incorrect date to slip through this filter, since it is possible for some of these confounding factors to accidentally change the isotope ratios in such a way as to produce something that looks like a good date: It would indeed be remarkable if this never happened, since one-in-a-thousand chances do in fact occur one time in a thousand.
But by the same token, the other times they don't, and so although any particular date produced by these methods might be called into question, it must be the case that the vast majority of dates that pass through these filters must be good; for we can hardly suppose that the confounding factors are actively conspiring to deceive us, and so these long-shot events must be as rare as statistical considerations would lead us to expect.
You might perhaps suggest that if some unknown factor, contrary to our present understanding of physics existed that sped up or slowed down radioactive decay in the past, then we would expect the radiometric dates to be concordant whether they were right or wrong. This is, as I say, contrary to our present understanding of physics, and so is mere unfounded speculation.
What is more, the reader should recollect that " radioactive decay " is not the name of one process; it is the name of any process that rearranges the nucleus. So to leave dates produced by different radiometric methods still concordant, nature would somehow have to conspire to fool us by changing the rates of alpha decay , of beta decay , and of electron capture , in such a way that the different dating methods based on these different modes of decay come up with the same dates. It determines the period during which certain object was last subjected to heat.
It is based on the concept that heated objects absorb light, and emit electrons.
The emissions are measured to compute the age. Differentiation Using a Venn Diagram. A Venn diagram depicts both dating methods as two individual sets. The area of intersection of both sets depicts the functions common to both. Take a look at the diagram to understand their common functions. When we observe the intersection in this diagram depicting these two dating techniques, we can conclude that they both have two things in common: Provide an idea of the sequence in which events have occurred.
Determine the age of fossils, rocks, or ancient monuments. Although absolute dating methods determine the accurate age compared to the relative methods, both are good in their own ways. Relative Dating Techniques Explained. How are Waterfalls Formed. Types of Metamorphic Rocks.
How are Rivers Formed? What Tools do Archaeologists Use. Why is Archaeology Important. Deepest Part of the Ocean. Interesting Facts About Hurricanes. How do Tornadoes Form. Who Invented the Battery. Lab Safety Rules for Kids. How Does a Diode Work? Who Invented the Computer? Uses of Radioactive Isotopes.