Go to our new-look site, it combines the Biotechnology and Science Learning Hubs with a new look and new functionality. This is our legacy site and is no longer maintained.

 

Timeline - Age of the earth

This interactive timeline provides a look at some of the historical aspects of finding out the age of the Earth. Find out more by browsing or searching the Science Learning Hub.

Acknowledgement
Image: Neville Gardner

1860

Earth ancient, but no date

Many geologists have evidence that Earth is ancient but cannot give an actual date as they only have relative dating methods. Some still use the Bible and other religious texts to support the idea that Earth is only about 6,000 years old.

1862

Earth 100 million years old

William Thomson (later called Lord Kelvin) estimates the Earth is 100 million years old, based on its cooling from a very hot creation. He is a long way out, because he does not know about the heat from natural radioactivity.

1896

Radioactivity discovered

Antoine Henri Becquerel discovers the radioactivity of uranium. The actual term ‘radioactivity’ is not used until 2 years later by Marie and Pierre Curie.

1902

Radioactive decay

Ernest Rutherford and Frederick Soddy work out the cause and nature of radioactive decay.

1903

Heat from radioactivity

George Darwin and John Joly point out that the newly discovered heat from radioactivity in rocks would upset earlier assumptions about the scientific age of the Earth.

1905

A way to date rocks

Ernest Rutherford suggests that it should be possible to use radioactive elements with long half-lives, such as uranium, to work out the ages of rocks.

1907

A new age for Earth

Bertram Boltwood uses the ratios of uranium and its decay product, lead, in rocks to suggest dates of 92–570 million years.

1911

Even earlier dates

Arthur Holmes improves on Boltwood’s work. Rock determined to be Carboniferous by relative dating is 340 million years old, a Precambrian rock is 1,640 million years old. These dates are not widely accepted, as they disagree with earlier dating methods.

1920

Mass spectrometer

Francis Aston invents the mass spectrometer for studying isotopes, which have only been known about for a few years.

1927

Not the oldest rocks

Arthur Holmes suggests that Earth is 1.6–3 billion years old. He realises that all the rocks being chemically dated were formed a long time after Earth was first formed.

1941

3.2 billion years old

EK Gerling estimates the age of the Earth as 3.2 billion years. He bases this on rocks he thinks are from the time when Earth was formed. These rocks are later shown to come from after Earth’s formation.

1946

A better instrument

Alfred Nier improves the mass spectrometer, making it easier for geologists around the world to measure isotopes.

1950

Looking for oldest rocks

By now, isotope dating has become fairly precise. There is still a problem finding rocks from the earliest formation of Earth, as they have mostly been reworked through the rock cycle.

1956

Meteorites

Clair Patterson realises that some meteorites were formed at the same time as the Earth and have stayed unchanged. He gets the age of 4.55 ± 0.3 billion years from the Canyon Diablo meteorite.

1972

Moon rock

The oldest rocks brought back from the Moon by the Apollo 17 mission have radiometric dates of up to 4.5 billion years. It is thought that the Moon formed at a similar time to Earth.

1983

Oldest crystals

Zircon crystals in Western Australia are dated to 4.2 billion years old. The zircon has now become part of younger rocks but has not changed since it was first formed.

2007

Oldest Earth rocks

The oldest known rocks, called Acasta gneiss, are found in Canada, dated at 4.03 billion years old. The 1983 Australian crystals are older, but are no longer in their original rock.

2010

Improved error range

Many meteorites have now been dated, improving Patterson’s 1956 age of the Earth of 4.55 ± 0.3 billion years to 4.55 ± 0.02 billion years. This reduction in error means that geologists have become more confident in their estimates of the age of the Earth.

Metadata