Researched
Radiometric age of the Earth
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