A Concordia diagram from Cornell showing the decay of parent uranium/lead isotopes to daughter uranium/lead isotopes.
The chart also shows known half-life decay rates in Ga's (billions of years).
Radiometric methods can date much older inorganic materials by using the decay of radioactive isotopes. By measuring the ratio of parent to daughter isotopes and calculating the half-life of the parent isotope, scientists can measure the age of the material.
| Item | Measured Age | Dating Method | Additional Information |
|---|---|---|---|
| Mt. Vesuvius eruption | 1,950 years old | K-Ar | Dated rocks from the 79 CE eruption |
| Hominid fossils (Sterkfontein, South Africa) | 3.4-3.7 million years old | U-Pb | Dated flowstones associated with Australopithecus fossils |
| Oldest known rock on Earth (Canada) | 4.03 billion years old | U-Pb | Nuvvuagittuq greenstone belt in Quebec |
| Martian meteorite ALH84001 | 4.09 billion years old | Rb-Sr | Meteorite found in Antarctica, believed to be from Mars |
| Moon rocks (Apollo missions) | 3.16-4.54 billion years old | Multiple methods | Various samples collected during Apollo missions |
| Acasta Gneiss (Canada) | 4.03 billion years old | U-Pb | One of the oldest known intact crustal fragments on Earth |
| Allende meteorite | 4.567 billion years old | Pb-Pb | One of the most studied meteorites, fell in Mexico in 1969 |
| Murchison meteorite | 4.565 billion years old | Rb-Sr | Carbonaceous chondrite that fell in Australia in 1969 |
| Pre-solar grains | Up to 7 billion years old | Various methods | Microscopic grains found in meteorites, older than the solar system |
A Concordia diagram from Cornell showing the decay of parent uranium/lead isotopes to daughter uranium/lead isotopes.
The chart also shows known half-life decay rates in Ga's (billions of years).
A real-world example of a Concordia diagram. Radiometric data taken from Geochron.
The chart shows that this sandstone most likely formed between 2.8 and 3.1 billion years ago.