Researched
Age of the Earth (4.55 Billion Years)
Clair Patterson dated meteorite lead in 1956 and fixed the age of the Earth at about 4.55 billion years.
Open in the interactive tree →Radioactive decay in minerals acts as a clock; Arthur Holmes used it from 1913 to show that rocks are hundreds of millions to billions of years old. Patterson's uranium-lead result ended the argument about Earth's age, and he later showed that leaded petrol had polluted the whole planet.
Prerequisites
- Geology and Deep Time1788
- First Geological Map (Smith)1815Radiometric dates calibrated the stratigraphic column first mapped by Smith
- Radioactivity1896Radioactive decay is the clock used for dating rocks
- Mass Spectrometry1919Mass spectrometers measure the isotope ratios used in radiometric dating
- Nuclear Physics1938
Unlocks
- Plate Tectonics1960s
- Ice Cores1987
- Asteroid Sample Return2020–2023Ages of asteroid material are fixed by radiometric dating