sciencetalk

EDIT 2: Bijna uit het oog verloren wat de eigenlijke vraag is van de topic. Het antwoord is ja: het is wel degelijk mogelijk om aardolie te dateren m.b.v. koolstofdatering. Meer informatie is hier te vinden.

Are There Things That Can't Be Carbon-Dated?

Yes. The method doesn't work on things which didn't get their carbon from the air. This leaves out aquatic creatures, since their carbon might (for example) come from dissolved carbonate rock. That causes a dating problem with any animal that eats seafood.

We can't date things that are too old. After about ten half-lives, there's very little C14 left. So, anything more than about 50,000 years old probably can't be dated at all. If you hear of a carbon dating up in the millions of years, you're hearing a confused report.

We can't date oil paints, because their oil is "old" carbon from petroleum.

We can't date fossils, for three reasons. First, they are almost always too old. Second, they rarely contain any of the original carbon. And third, it is common to soak new-found fossils in a preservative, such as shellac. It is also standard to coat fossils during their extraction and transport. Acetone is sometimes used while extracting fossils, because it dissolves dirt. In short, unless you have evidence to the contrary, you should assume that most of the carbon in a fossil is from contamination, and is not originally part of the fossil.

We also can't date things that are too young. The nuclear tests of the 1950's created a lot of C14. Also, humans are now burning large amounts of "fossil fuel". As the name suggests, fossil fuel is old, and no longer contains C14. Both of these man-made changes are a nuisance to carbon dating.

If you hear of a living tree being dated as a thousand years old, that is not necessarily an example of an incorrect dating. Trees only grow on the outside. Wood taken from the innermost ring really is as old as the tree.

Hier ben ik bang dat je de tekst misleest. Olie van 9000 jaar oud bestaat niet.

Aangezien oa.er datummetingen worden gedaan op basis van verminderde radio-activiteit van uranium 235 en men heel ver in het verleden van onze aarde kan duiken,vraag ik me af welke vorm van U235 de meeste radioactiviteit heeft

en wanneer die is gevormd.

Volgens mij werd de geologische tijdschaal opgesteld d.m.v. radiometrische datering. Lees hier meer. Er is echter ook scepsis t.o.v. deze methode en binnen de wetenschappelijke wereld is er ook onduidelijkheid over de precieze datering van de oudere tijdvakken.

Time lords

Geologists have come to an international agreement about the timeline of Earth’s history. But the results are not quite set in stone, as John Whitfield discovers.

Silurian, Devonian, Triassic: the names seem as solid and permanent as rocks themselves. But in fact, like fashions in hair or hem-length, the geological divisions of our planet’s timeline are prone to change. Geologists argue over what defines the boundaries between these periods, and disagree over exactly how old they are. The end of the Jurassic period, for instance, has wobbled by more than 30 million years since it was dated in the 1930s (refs 1, 2).

This summer, the first fully revised geological timescale for 15 years will be published3, helping to clear up some of the confusion. The new scale will help Earth scientists speak to one another in a common language, and the dates will help to answer questions about what caused various mass extinctions and changes in climate. The project will even have an impact on oil companies, which base their exploration programmes in part on estimates of the age of rocks.