Difference between revisions of "Radiometric dating"

From Conservapedia
Jump to: navigation, search
(Rate of decay)
m (Outside influences)
Line 21: Line 21:
 
For example, with [[Uranium-lead dating]] with the crystallization of magma, this remains a closed system until the uranium decays.  As it decays, it disrupts the crystal and allows the lead atom to move.  Likewise, heating the rock such as [[granite]] forms [[gneiss]] or [[basalt]] forms [[schist]].  This can also disrupt the ratios of lead and uranium in the sample.
 
For example, with [[Uranium-lead dating]] with the crystallization of magma, this remains a closed system until the uranium decays.  As it decays, it disrupts the crystal and allows the lead atom to move.  Likewise, heating the rock such as [[granite]] forms [[gneiss]] or [[basalt]] forms [[schist]].  This can also disrupt the ratios of lead and uranium in the sample.
  
Dating metamorphic rocks has lead to incorrect dating of the Grand Canyon by the RATE Project (Radioisotopes and the Age of the Earth).<ref>[http://www.icr.org/index.php?module=articles&action=view&ID=42 Radioisotope Dating of Grand Canyon Rocks: Another Devastating Failure for Long-Age Geology] (Note: be sure to make note of the first sentence of the second paragraph)</ref><ref>[http://www.answersincreation.org/ratedeception.htm Critique of RATE's methods] Answers in Creation</ref>
+
Dating metamorphic rocks has led to incorrect dating of the Grand Canyon by the RATE Project (Radioisotopes and the Age of the Earth).<ref>[http://www.icr.org/index.php?module=articles&action=view&ID=42 Radioisotope Dating of Grand Canyon Rocks: Another Devastating Failure for Long-Age Geology] (Note: be sure to make note of the first sentence of the second paragraph)</ref><ref>[http://www.answersincreation.org/ratedeception.htm Critique of RATE's methods] Answers in Creation</ref>
  
 
==Some major methods of radiometric dating==
 
==Some major methods of radiometric dating==

Revision as of 22:35, April 24, 2007

Radiometric dating is using a radioactive process to determine the age of an item.[1] Radiometric dating is mostly used to determine the age of rocks (though in the case of Radiocarbon dating can date wood, cloth, skeletons, and other organic material), and relies on the well-established function for exponential decay . Different radiometric techniques are calibrated in different ways; for example, radiocarbon dating is calibrated by dating wood that has been dated through the process of dendrochronology.

Key assumptions

Ratios of materials

Radiometric dating works on the assumption that there is some natural level of radioactive material and material that it will decay to in nature. For example, with Radiocarbon dating, this is carbon 14 and Nitrogen 14. The level of carbon 14 in the environment is stable with the two exceptions of bomb carbon and burning of ancient fuels (increasing the amount of carbon 12 in the environment). Both of these can be removed by using wood from 1890 - prior to the widespread use of fossil fuels and well before the creation of the nuclear bomb.

With substances such as uranium, there is no creation of new uranium in the history of the world (with the exception of the very recent phenomenon of nuclear enrichment - which never gets back into ancient rocks so this is moot).

Younge Earth Creationists assert that the rate of formation of carbon 14 changed with creation and the flood leading to incorrect results for dating.

Rate of decay

The rate of decay of a radioactive material is constant. This is based upon knowledge of quantum mechanics and the structure of the atom.[2]Atoms consist of a heavy central core called the nucleus surrounded by clouds of lightweight particles (electrons), called electron shells. The energy locked in the nucleus is enormous, but fortunately it cannot easily be released. The phenomenon we know as heat is simply the jiggling around of atoms and their components, so in principle a high enough temperature could cause the components of the core to break out. However, the temperature required to do this is in in the millions of degrees, so this cannot be achieved by any natural process that we know about. The second way that a nucleus could be disrupted is by particles striking it. However, the nucleus has a strong positive charge and the electron shells have a string negative charge. Any incoming negative charge would be deflected by the electron shell and any positive charge that penetrated the electron shells would be deflected by the positive charge of the nucleus itself. Non-charged particles such as neutrons can penetrate to the nucleus and disrupt it (this is how a nuclear bomb works) but such a process will either cause more neutrons to emerge at a rapidly escalating rate - which would be very obvious to say the least - or it will fizzle out in a tiny fraction of a second. It thus seems very unlikely that radioactive decay rates can be altered without this being obvious.

Outside influences

It is important that the sample not have had any outside influences. One example of this can be found in metamorphic rocks.[3] This does not mean that all rock samples are unreliable, but it is possible to account for a process which throws off the data for metamorphic rocks.

For example, with Uranium-lead dating with the crystallization of magma, this remains a closed system until the uranium decays. As it decays, it disrupts the crystal and allows the lead atom to move. Likewise, heating the rock such as granite forms gneiss or basalt forms schist. This can also disrupt the ratios of lead and uranium in the sample.

Dating metamorphic rocks has led to incorrect dating of the Grand Canyon by the RATE Project (Radioisotopes and the Age of the Earth).[4][5]

Some major methods of radiometric dating

There are several major types of radiometric dating in use:[6],[7]

  1. Radiocarbon dating, also called carbon dating
  2. Potassium-argon dating
  3. Uranium-lead dating
  4. Uranium-thorium
  5. Rubidium-strontium dating

References

  1. Radiometric Time Scale USGS
  2. Principles of Quantum Mechanics page 89
  3. Radiometric Dating Course notes for EENS 211 at Tulane University
  4. Radioisotope Dating of Grand Canyon Rocks: Another Devastating Failure for Long-Age Geology (Note: be sure to make note of the first sentence of the second paragraph)
  5. Critique of RATE's methods Answers in Creation
  6. Quarternary Dating Methods, by M. Walker (Wiley & Sons, 2005).
  7. Isotopes: Principles and Applications, by G. Faure and T. Mensing (Wiley & Sons, 2005).