Geological time
The timescale of the Earth
Geologists split the Earth’s 4,540 million years into eons, eras, periods and epochs, agreed worldwide by the International Commission on Stratigraphy. This is its chart of June 2026, down to every epoch. Choose any band to zoom in, and switch between a stretched view and true scale.
Timescale explorer
Whole Earth
4,567 million years ago to now
The chart starts 4,567 million years ago, with the oldest solid grains in the Solar System, found inside meteorites. The Earth itself is a little younger, about 4,540 million years old. The Phanerozoic, the eon of visible animal life, is only the last 538.8 million years: about an eighth of the whole.
How to read the names
The chart nests like a set of drawers. An eon holds eras, an era holds periods, and a period holds epochs, which are cut again into ages. We are living in the Phanerozoic eon, the Cenozoic era, the Quaternary period, the Holocene epoch and the Meghalayan age.
Each unit has two names on the chart: one for the rock laid down (an erathem, a system, a series, a stage) and one for the time it took to lay down (an era, a period, an epoch, an age). That is why some epochs are called Lower and Upper: those are the rock names, and in time they are the Early and Late epochs.
What is settled, and what is not
The chart looks exact, but it shows its doubts if you know where to look. We show them too.
- Uncertain agesPlus or minus
- Many boundaries come with a margin. The start of the Devonian is given as 419.62 million years ago, plus or minus 1.36 million years. Where the chart gives a margin, the explorer above says so.
- ApproximateStill marked with a ~
- Some boundaries have only an approximate age on the chart, such as the start of the Ediacaran, about 635 million years ago, and the starts of three of the four Cambrian series.
- UnnamedCambrian Series 2
- Not every unit has a name yet. The second series of the Cambrian is still just called Series 2: the chart prints it in italics to show it is informal.
- RejectedThe Anthropocene
- Many people call our time the Anthropocene, the age of human impact. In 2024, after 15 years of debate, geologists voted not to make it a formal epoch. Officially we are still in the Holocene. The international bodies say the word will remain an invaluable way to describe human impact on the Earth, just not as a unit of the timescale. For the human side of the story, see the eras of human history on our sister site, Our Centuries.
Every unit, in a table
Show all 67 eons, eras, periods and epochs
| Name | Began | Ended |
|---|---|---|
| Phanerozoic | 538.8 Ma ±0.6 | now |
| Proterozoic | 2,500 Ma | 538.8 Ma |
| Archean | 4,031 Ma ±3 | 2,500 Ma |
| Hadean | 4,567 Ma | 4,031 Ma |
| Name | Began | Ended |
|---|---|---|
| Cenozoic | 66 Ma | now |
| Mesozoic | 251.902 Ma ±0.024 | 66 Ma |
| Paleozoic | 538.8 Ma ±0.6 | 251.902 Ma |
| Neoproterozoic | 1,000 Ma | 538.8 Ma |
| Mesoproterozoic | 1,600 Ma | 1,000 Ma |
| Paleoproterozoic | 2,500 Ma | 1,600 Ma |
| Neoarchean | 2,800 Ma | 2,500 Ma |
| Mesoarchean | 3,200 Ma | 2,800 Ma |
| Paleoarchean | 3,600 Ma | 3,200 Ma |
| Eoarchean | 4,031 Ma ±3 | 3,600 Ma |
| Name | Began | Ended |
|---|---|---|
| Quaternary | 2.58 Ma | now |
| Neogene | 23.04 Ma | 2.58 Ma |
| Paleogene | 66 Ma | 23.04 Ma |
| Cretaceous | 143.1 Ma ±0.6 | 66 Ma |
| Jurassic | 201.4 Ma ±0.2 | 143.1 Ma |
| Triassic | 251.902 Ma ±0.024 | 201.4 Ma |
| Permian | 298.9 Ma ±0.15 | 251.902 Ma |
| Carboniferous | 358.86 Ma ±0.19 | 298.9 Ma |
| Devonian | 419.62 Ma ±1.36 | 358.86 Ma |
| Silurian | 443.1 Ma ±0.9 | 419.62 Ma |
| Ordovician | 486.85 Ma ±1.5 | 443.1 Ma |
| Cambrian | 538.8 Ma ±0.6 | 486.85 Ma |
| Ediacaran | ~635 Ma | 538.8 Ma |
| Cryogenian | ~720 Ma | 635 Ma |
| Tonian | 1,000 Ma | 720 Ma |
| Name | Began | Ended |
|---|---|---|
| Holocene | 0.0117 Ma | now |
| Pleistocene | 2.58 Ma | 0.0117 Ma |
| Pliocene | 5.333 Ma | 2.58 Ma |
| Miocene | 23.04 Ma | 5.333 Ma |
| Oligocene | 33.9 Ma | 23.04 Ma |
| Eocene | 56 Ma | 33.9 Ma |
| Paleocene | 66 Ma | 56 Ma |
| Upper Cretaceous | 100.5 Ma ±0.1 | 66 Ma |
| Lower Cretaceous | 143.1 Ma ±0.6 | 100.5 Ma |
| Upper Jurassic | 161.5 Ma ±1 | 143.1 Ma |
| Middle Jurassic | 174.7 Ma ±0.8 | 161.5 Ma |
| Lower Jurassic | 201.4 Ma ±0.2 | 174.7 Ma |
| Upper Triassic | ~237 Ma | 201.4 Ma |
| Middle Triassic | 247 Ma | 237 Ma |
| Lower Triassic | 251.902 Ma ±0.024 | 247 Ma |
| Lopingian | 259.857 Ma ±0.084 | 251.902 Ma |
| Guadalupian | 274.4 Ma ±0.4 | 259.857 Ma |
| Cisuralian | 298.9 Ma ±0.15 | 274.4 Ma |
| Upper Pennsylvanian | 307 Ma ±0.1 | 298.9 Ma |
| Middle Pennsylvanian | 315.2 Ma ±0.2 | 307 Ma |
| Lower Pennsylvanian | 323.4 Ma ±0.4 | 315.2 Ma |
| Upper Mississippian | 330.3 Ma ±0.4 | 323.4 Ma |
| Middle Mississippian | 346.7 Ma ±0.4 | 330.3 Ma |
| Lower Mississippian | 358.86 Ma ±0.19 | 346.7 Ma |
| Upper Devonian | 382.31 Ma ±1.36 | 358.86 Ma |
| Middle Devonian | 393.47 Ma ±0.99 | 382.31 Ma |
| Lower Devonian | 419.62 Ma ±1.36 | 393.47 Ma |
| Pridoli | 422.7 Ma ±1.6 | 419.62 Ma |
| Ludlow | 426.7 Ma ±1.5 | 422.7 Ma |
| Wenlock | 432.9 Ma ±1.2 | 426.7 Ma |
| Llandovery | 443.1 Ma ±0.9 | 432.9 Ma |
| Upper Ordovician | 458.2 Ma ±0.7 | 443.1 Ma |
| Middle Ordovician | 471.3 Ma ±1.4 | 458.2 Ma |
| Lower Ordovician | 486.85 Ma ±1.5 | 471.3 Ma |
| Furongian | ~497 Ma | 486.85 Ma |
| Miaolingian | ~506.5 Ma | 497 Ma |
| Series 2 | ~521 Ma | 506.5 Ma |
| Terreneuvian | 538.8 Ma ±0.6 | 521 Ma |
Sources
- International Commission on Stratigraphy, International Chronostratigraphic Chart, v2026/06
- Commission for the Geological Map of the World, via the Geologic TimeScale Foundation, Standard colour codes for the geological time scale (RGB set)
- US Geological Survey (Dalrymple), Age of the Earth
- J. N. Connelly and others, Science 338, The absolute chronology and thermal processing of solids in the solar protoplanetary disk (2012)
- US Geological Survey Geologic Names Committee (Fact Sheet 2018–3054), Divisions of geologic time: major chronostratigraphic and geochronologic units
- International Commission on Stratigraphy and International Union of Geological Sciences, Joint statement by the IUGS and ICS on the Anthropocene vote
- Nature (news, 6 March 2024), Geologists reject the Anthropocene as Earth’s new epoch, after 15 years of debate