Dating very old rocks
This information has also helped determine the age of the Earth itself.While the oldest known rocks on Earth are about 3.5 billion years old, researchers have found zircon crystals that are 4.3 billion years old [source: USGS].Recent research by a team of creation scientists known as the RATE (arth) group has demonstrated the unreliability of radiometric dating techniques.Even the use of isochron dating, which is supposed to eliminate some initial condition assumptions, produces dates that are not reliable.This is what archaeologists use to determine the age of human-made artifacts. The half-life of carbon-14 is only 5,730 years, so carbon-14 dating is only effective on samples that are less than 50,000 years old.Dinosaur bones, on the other hand, are millions of years old -- some fossils are billions of years old.Radiometric dating isn't the only method of determining the age of rocks.Other techniques include analyzing amino acids and measuring changes in an object's magnetic field.
Some of the isotopes used for this purpose are uranium-238, uranium-235 and potassium-40, each of which has a half-life of more than a million years.
There are three main assumptions that must be made to accept radiometric dating methods.
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