At death, carbon 14 levels decrease due to decay, while carbon 12 remains constant.
Scientists can measure the ratio of carbon 14 to carbon 12 (a stable form).
Dating Techniques Radiometric Dating Radiocarbon Uranium-lead Potassium-argon Rubidium-strontium Samarium-neodymium Rhenium-osmium Lutetium-hafnium Isochron Fission track Thermoluminescence Optically stimulated luminescence Electron spin resonance Dendrochronology Paleo/Archaeo-magnetism Stratigraphic Superposition Molecular Clock Radiocarbon Dating (Riddle, Dating) A radioactive isotope is an unstable form of an element. Carbon 14 is unstable and decays to Nitrogen at a known rate.
Carbon 14 and carbon 12 (the stable form) are present in the atmosphere and are metabolized into the bodies of all living things in the same ratio as in the atmosphere.
This amount of carbon was on the surface of the earth in the past.
The carbon 14 would have been much diluted and the carbon ratio smaller.
These dates should have all agreed if the radiometric dating assumptions are correct (Snelling, 2007). The rock to be dated must be in a closed system for the dating process to work.
However, it is impossible to know what forces of nature have acted on a rock during its history before it was uncovered and sampled.
Volcanically Expelled Carbon Carbon 12 exists deep in the earth.
Scientists date rocks by measuring the uranium and its decay products.
Scientists must use several assumptions to arrive at a date: At the time of origin, there was only Uranium, and no daughter elements.
If the ratio at death is known, then the period of time needed to decay to the present ratio may be calculated.
Carbon 14 is created in the atmosphere when carbon 12 is bombarded by cosmic rays. It is estimated that it would take 10,000 to 30,000 years for the atmosphere to reach an equilibrium between carbon 12 and carbon 14.
The Koongarra Formation (Snelling, 1981) A rock formation in Koongarra, Australia was uranium dated using several core samples with very erratic results.