Radiocarbon dating of volcanic rocks
Scientists determined the Earth's age using a technique called radiometric dating.
Radiometric dating is based upon the fact that some forms of chemical elements are radioactive, which was discovered in 1896 by Henri Becquerel and his assistants, Marie and Pierre Curie.
Over time, radioactive isotopes change into stable isotopes by a process known as radioactive decay.
Some radioactive parent isotopes decay almost instantaneously into their stable daughter isotopes; others take billions of years.
At time 1, 50% of the parent atoms remain; at time 2, only 25% remain, and so on.The discovery gave scientists a tool for dating rocks that contain radioactive elements.Many elements have naturally occurring isotopes, varieties of the element that have different numbers of neutrons in the nucleus.Radiometric dating works best on igneous rocks, which are formed from the cooling of molten rock, or magma.
After one half-life, 50 percent of the original parents remains; after two, only 25 percent remains, and so on.Decay curve of a radioactive element with a half-life equal to one time unit.