However, because plate tectonics constantly changes and revamps the crust, the first rocks have long since been recycled, melted down and reformed into new outcrops.
In the early 20th century, scientists refined the process of radiometric dating.
More than 70 meteorites have fallen to Earth to have their ages calculated by radiometric dating.
Shards of that asteroid have been collected from the crater rim and named for the nearby Canyon Diablo.In an effort to further refine the age of Earth, scientists began to look outward.The material that formed the solar system was a cloud of dust and gas that surrounded the young sun.In 1953, Clair Cameron Patterson measured ratios of lead isotopes in samples that put tight constraints on Earth's age.The Canyon Diablo meteorite is important because it represents a class of meteorites with components that allow for more precise dating.
Several attempts to scientifically date the planet have occurred over the past 400 years.