Radiometric dating uses what isotopes
Some evidence is also presented to show that radiometric results that are in agreement with the accepted geological time scale are selectively published in preference to those results that are not in agreement.
The geological time scale and an age for the Earth of 4.5 b.y.
Plants and animals assimilate carbon 14 from carbon dioxide throughout their lifetimes.
When they die, they stop exchanging carbon with the biosphere and their carbon 14 content then starts to decrease at a rate determined by the law of radioactive decay.
Radiometric dating not only supports the geologic "evolution" of the Grand Canyon, it validates a central tenet in a much different theory of evolution - a theory introduced by Charles Robert Darwin in his 1859 publication, An important criticism of Darwin's theory of evolution was its requirement for "an almost infinite number of generations", when evidence at the time suggested earth was less than 100 million years old.
Nearly 50 years after Darwin published , research on radioactive elements in rocks provided the first reliable evidence that the earth was old enough to accommodate the evolution of complex organisms.
Their method, a type of radiometric dating called uranium-lead (U-Pb) dating, relies on the fact that uranium isotopes radioactively decay to form lead isotopes.
By comparing the amount of each isotope in a sample, the age of the sample can be calculated.
They have the same ratio of carbon-14 to carbon-12 as the atmosphere, and this same ratio is then carried up the food chain all the way to apex predators, like sharks.American physical chemist Willard Libby led a team of scientists in the post World War II era to develop a method that measures radiocarbon activity.