How accurate is carbon dating? What is the most accurate method of dating fossils, rock etc., or manuscripts.?

Answer 1

the carbon dating method is not used to determine the age of fossils or rocks. Carbon 14 has a relatively short half-life, which makes it useful only to date once-living organisms that are known or suspected to be less than about 40-50 thousand years old. But there are many other isotopes that can be used to date rocks and the fossils found within them, and the process works the same way. Also, the correct isoptope must be used to test the age of the object. Some isotopes have a very, very long half-life, and those isotopes can only be used to test objects that are, of course, very old. Use that same isotope to date a rock that just left the mouth of a volcano two weeks ago, and you will get a false reading. And vice versa.

Isotopic dating methods rely on the constant rate of decay from radioactive isotopes into daughter elements. When scientists test a rock, they draw a conclusion of it's age.

This conclusion is based upon carefully designed and conducted experiments that compare the ratios in rock samples of parent elements to daughter elements ( some of which would have been from radioactive decay of the parent, some of which may have been present in the sample at the time of formation). Since radioactive decay is known to occur at a constant rate, the age of a rock can be determined from the ratio of the parent element to the daughter element. The concerns about these dating methods were exactly the same that creationists continue to raise - presence of the daughter element at the time the rock was formed and possible loss / gain of either the parent or daughter element at some point in the history of the rock. For this reason, the tests were designed to account for those possibilities.

Initial daughter element can often be accounted for by either measuring the amount of an isotope of the daughter element (the ratio of isotopes are almost always constant). Another possibility is (as in the case of the potassium - argon - K-Ar method) that because the daughter element is gaseous, it would escape from the rock when the rock was molten. Once the rock cooled, the gaseous daughter would be trapped in the rocks crystal structure and could no longer escape. By experimentation, scientists have determined which rocks are suitable for various dating techniques. For K-Ar, for example, igneous rocks are good candidates for testing because they formed directly from molten magma and have a simple history. Metamorphic rocks do not work well because heating events in their history have allowed the escape of Argon (daughter element) and thus will indicate an age too young for the sample. Sedimentary rocks do not work because they are made up of a mixture of deposits of many other types of rocks, each of which would point to a different age. At any rate, scientists have devoted a great deal of effort to determining exactly which dating methods are appropriate for which types of rocks.

The other problem to avoid when dating rocks is the possibility that changes to the rock have caused loss or gain of either the parent or daughter element - this would lead to a false date (too old if parent element were lost, too young if daughter element were lost). I know of two methods that have been designed that can account for this possibility - isochron dating and the uranium-thorium-lead discordia / concordia method (actually three independent age calculations for one sample). Both of these methods have internal checks for the possible loss / gain of elements to the rock.

Creationists want the world to think that geologists just grab a rock and throw any old radiometric test at it and poof - there's the age of the rock. Reality is far more complex. If you examine the extensive research in the field of geochronology, you will see that one of the most important criteria in dating a sample lies in choosing an appropriate dating method for the sample. From G. Brent Dalrymple (see below):

One of the principal tasks of the geochronologist is to select the type of the material used for a dating analysis. A great deal of effort goes into the sample selection, and the choices are made before the analysis, not on the basis of the results. Mistakes are sometimes made but are usually caught by the various checks employed in the well-designed experiment. That is why you might have various ages for a certain rock, until all the tests are in and all of the checks have been completed.

The most compelling argument for an age of the earth of 4.5 billion years are the large number of independent tests that have been used to confirm this date. These tests have been performed on what are thought to be the earth's oldest surviving rocks, meteorites, and moon rocks. These tests have consistently given the same ages for each of these objects.
Examples include:

The Earths Oldest Rock's
Description Technique Age (in billions of years)

Amitsoq gneisses (western Greenland) Rb-Sr isochron 3.70 +- 0.12
Amitsoq gneisses (western Greenland) 207Pb-206Pb isochron 3.80 +- 0.12
Amitsoq gneisses (western Greenland) (zircons) U-Pb discordia 3.65 +- 0.05
Amitsoq gneisses (western Greenland) (zircons) Th-Pb discordia 3.65 +- 0.08
Amitsoq gneisses (western Greenland) (zircons) Lu-Hf isochron 3.55 +- 0.22
Sand River gneisses (South Africa) Rb-Sr isochron 3.79 +- 0.06

These are the oldest of the rocks dated on the earth so far (as of 1997). These are metamorphic rocks and thus have had some of their "history" lost - metamorphosis fully or partially resets the radiometric ages of rocks pointing to younger ages than the true age of the original rock. Older rocks may have been lost due to erosion or have not yet been discovered. Or they could have been destroyed by the subduction from plate tectonics.

For many more examples of the consistancy of dating the same rocks with multiple methods, see Consistent Radiometric Dates by Joe Meert, a Geologist at the University of Florida. Dr. Meert's examples not only show that multiple radiometric methods come up with consistent dates for samples from the same locations, but that these results are also consistant with the paleomagnetic signature of the rocks, the position where the rocks would be expected to be (due to continental drift) at the time they were formed, and the cooling curves for the rocks. (Cooling curves deal with the fact that the different radiometric isotopes become "frozen" in the rocks at different temperatures. The higher the closure temperature for an isotope, the older the rock will be as dated by that isotope.) All of this consistancy rules out all of the arguments creationists attempt to make against radiometric dating techniques.
http://www.gate.net/~rwms/AgeEarth.html

Scientists also use geological principals to give relative dates to gelogical strata. http://homepage.usask.ca/~mjr347/prog/geoe118/geoe118.039.html, http://www.indiana.edu/~ensiweb/lessons/varves.html

Last but not least, scientists also use the Paleomagnetism studies of the ocean floor, which chronicles many polar shifts during the changing history of the ocean floor, to determine the age of the earth. A similar process happens in rock particles that are laid down as sedimentary rock, although the accruacy of this method of dating is not as accurate. It is still useful, however, in conjunction with other methods.

All of these methods, used independently, give the same approximate age of the earth; 4.56 billion years. They also give correlating dates of rocks when the proper methods of sampling are used.

In the case of fossils, scientists can date the geological strata in which the fossil is found. Determine when the layer of sediment was laid down, and you can know the date of the fossil that was buried in it.

For a detailed explaination of the dating method for manuscripts, visit http://www.skypoint.com/~waltzmn/MSDating.html and http://scriptorium.lib.duke.edu/papyrus/texts/manuscripts.html.

Answer 2

Those factors are taken into account when doing the dating. In some areas, C14 dating cannot even be used, so other methods need to be done to date the sample. Scientists are not idiots. They know about these things, and correct for them. If they cannot correct for them, then they cannot use the method for that sample. For example, the carbon that is dated in organic remains comes from the atmosphere, but the amount of C14 in the atmosphere changes over time. Scientists can use ice cores from Antarctica which have trapped C14 in the ice after snow falls over 100,000s of years to determine how much to correct for a sample's dates if the stratigraphy provides a rough estimate. Take into account also the multitude of other dating isotopic dating practices that are used to check and double check the date and you end up getting a really good idea of the time period, within a few years. Simple.

Answer 3

carbon dating is very accurate, and i would say the most accurate method of dating manuscripts would be to look for a date on it, otherwise carbon dating

when i say very i mean within 100 thousand years or so, depending on how old

Answer 4

Fossils are dated relative to the nearest absolutely dated igneous rock with the use of the law of superposition and the law of intrusion.

Answer 5

I don't think it is very accurate at all. I read a story a few days abo about some human fossils that were found in Africa... at 1st they said they were 3.3 mil years old, then they changed their story and said 4.5 mil yo, now they are saying they were wrong all along and now they believe them to be 2.2 mil years old... hmmm.... not so accurate!

Answer 6

Fossils? Doubtful
Rocks? Unlikely - very
Manuscripts? yes, very good.

Answer 7

this site has all the methods use in dating.

http://archaeology.about.com/od/dating/Dating_Archaeological_Sites_and_Artifacts.htm