Radiometric dating, radioactive dating or radioisotope dating is a technique which is used to date materials such as rocks or carbon, in which trace radioactive impurities were selectively incorporated when they were formed.

How old are rocks at the beach?

The next oldest seafloor is found at the margins of the north Atlantic Ocean and the northwestern Pacific Ocean, as far as possible from the mid-ocean ridges where they were created. These parts of the seafloor are about 200 million years old. Age of the oceanic crust.