How old the Earth is, what lived at every point in deep time, which animals dominated each era, and the five mass extinctions that reset the planet. Drag the bar to travel from the magma ocean to the Anthropocene.
The planet finished accreting out of the debris disk around the young Sun about 4,540,000,000 years ago. That estimate comes from radiometric dating of the oldest calcium-aluminium inclusions in meteorites and of the oldest terrestrial zircons — the method is explained in the FAQ below.
Click or drag anywhere on the bar to jump through 4.5 billion years. The panel reads out which eon, era and period you are standing in, what was living at that moment, and the most recent milestone before your position. Use the arrow keys for fine control once the bar has focus.
Logarithmic scale — every tick is 10× older than the one to its right, so the Archean and Homo sapiens both stay readable.
Hadean
No confirmed life. A global magma ocean, the Moon-forming impact at roughly 4.51 Ga, and the condensation of the first oceans near 4.4 Ga.
Squash 4.54 billion years into a single day that starts at midnight. Hover or focus any marker for the clock time it lands on. Human history is the blink of an eye at the very end — the last few seconds of the day.
Markers are placed at their true proportional position: the leftmost event sits a fraction of a millimetre from midnight, and the last three bunch up in the final pixel of the day.
The official subdivision of Earth history, from the International Chronostratigraphic Chart. Dates are millions of years ago (Ma); the length column shows how brief each interval really is compared with the eons above it.
| Eon | Era / period | Start (Ma) | End (Ma) |
Length | What dominated |
|---|---|---|---|---|---|
| Hadean | Hadean eon | 4,567 | 4,031 | 536 Myr | No confirmed lifeMagma ocean; Moon-forming impact ~4.51 Ga; first water ~4.4 Ga. |
| Archean | Archean eon | 4,031 | 2,500 | 1,531 Myr | CyanobacteriaStromatolite mats in shallow seas, the first unmistakable fossil record ~3.5 Ga. |
| Paleoproterozoic | 2,500 | 1,600 | 900 Myr | Cyanobacteria, first eukaryotesGreat Oxidation Event ~2.4 Ga; oxygen crashes the methane greenhouse ~2.1 Ga. | |
| Mesoproterozoic | 1,600 | 1,000 | 600 Myr | Single-celled eukaryotesRed and green algae appear; first sexual reproduction in algae ~1.2 Ga. | |
| Proterozoic | Neoproterozoic (Tonian–Cryogenian) |
1,000 | 635 | 365 Myr | Microbes onlySnowball Earth glaciations 720–635 Ma; the cap carbonate is the last global melt. |
| Ediacaran | 635 | 538.8 | 96 Myr | First large soft-bodied animalsDickinsonia, Charnia, the frond-like Ediacaran biota; almost no hard parts. | |
| Cambrian Period starts the Phanerozoic |
538.8 | 486.85 | 52 Myr | Trilobites & anomalocarididsCambrian explosion: nearly every animal body plan in living memory appears in ~20 Myr. Land is lifeless rock. | |
| Phanero- zoic | Paleozoic · Ordovician | 486.85 | 443.1 | 44 Myr | Shelled cephalopods, corals, jawless fishGreat Ordovician Biodiversification Event; ends in the first mass extinction. |
| Paleozoic · Silurian | 443.1 | 419.62 | 24 Myr | Jawed fishPlacoderms and the first sharks; first land plants and the first land arthropods. | |
| Paleozoic · Devonian | 419.62 | 358.86 | 61 Myr | The Age of FishesSharks and ray-finned fish; first forests, first four-legged vertebrates (tetrapods). | |
| Paleozoic · Carboniferous | 358.86 | 298.9 | 60 Myr | Giant arthropods, amphibians, first reptilesCoal-swamp forests; oxygen near 35%, which is why insects grew so large. | |
| Paleozoic · Permian | 298.9 | 251.9 | 47 Myr | Synapsids, seed plantsPangaea assembled; conifers and cycads spread, then the largest extinction in Earth history. | |
| Mesozoic · Triassic | 251.9 | 201.4 | 51 Myr | First dinosaurs, first mammalsMarine reptiles and ammonoids; archosaurs dominate the land after the Permian crash. | |
| Mesozoic · Jurassic | 201.4 | 143.1 | 58 Myr | Sauropods and theropodsGymnosperm forests; first birds (Archaeopteryx); plesiosaurs and ichthyosaurs at sea. | |
| Mesozoic · Cretaceous | 143.1 | 66 | 77 Myr | Dinosaurs, flowering plants, insectsThe Cretaceous Terrestrial Revolution: angiosperms, bees and ants transform land ecosystems. | |
| Cenozoic · Paleogene | 66 | 23.03 | 43 Myr | Mammals & birdsThey move into every ecological niche dinosaurs left empty; first primates ~56 Ma. | |
| Cenozoic · Neogene | 23.03 | 2.58 | 20 Myr | Grasslands, horses, apesC4 grasses spread, open habitats form, whales return to the sea, hominins appear ~7 Ma. | |
| Cenozoic · Quaternary | 2.58 | 0 | 2.6 Myr | Homo sapiens, and usIce age cycles, megafauna vanish, agriculture and cities; today is a 0.057% sliver of the bar. |
Five events stand out because each one erased a large share of species worldwide within a geologically short window. The bar under each date shows the estimated share of species lost; the figures are ranges because they depend on which group of organisms and which rock record you count.
The first big one, and the only mass extinction driven by cold. Gondwana drifted over the south pole, its ice cap grew, and sea level fell worldwide by up to 100 m as water locked onto land.
Not one event but a long series of pulses spread over roughly 30 million years, driven by repeated anoxia. Warm, nutrient-rich water flooded the shelves and stagnant, oxygen-free bottom waters spread.
The deadliest event in Earth history. Siberian Traps volcanism pumped out so much CO2 that oceans warmed by up to 10 °C, turned acidic and lost their oxygen. Marine life recovered only after 5–10 million years.
The Central Atlantic Magmatic Province erupted as Pangaea split, releasing enough carbon to trigger a brief global warming. Many extinction "events" of this size are probably this kind of volcanism, not an impact.
A 10–15 km asteroid struck shallow sea at what is now the Yucatán Peninsula, the Chicxulub crater. The impact winter blocked sunlight for years and acid rain followed. Non-avian dinosaurs, ammonites, mosasaurs and pterosaurs are gone.
The Big Five are the largest, but deep time has other catastrophes worth naming:
The landmarks that most changed the course of life. Each one is also a marker on the scrubber bar above, so you can jump there and read the era it falls in.
About 4,540,000,000 years old — 4.54 billion. The planet finished forming out of the debris around the young Sun roughly 4,567 million years ago, so the headline figure carries an uncertainty of a few tens of millions of years. On the 24-hour clock above, Earth forms at midnight and the present moment is the stroke of midnight 24 hours later.
It is about 57 million lifetimes. Everything humans have ever done fits in the final seconds of a single day: on the 24-hour scale, Homo sapiens appeared roughly 6 seconds before midnight, agriculture about 0.23 seconds before, and writing about 0.1 seconds before. Dinosaurs lasted 165 million years — about 52 minutes of that day.
A mass extinction wipes out a large share of species worldwide within a geologically short time. Geologists recognise five Big Five events, all inside the Phanerozoic eon: the End-Ordovician (443 Ma), Late Devonian (372 Ma), End-Permian (251.9 Ma), End-Triassic (201.4 Ma) and End-Cretaceous (66 Ma). The End-Permian was the worst, killing an estimated 90–96% of marine species.
For most of Earth's history life was microscopic. Cyanobacteria built stromatolite reefs for over two billion years, then soft-bodied Ediacaran animals appeared around 635 Ma, and the Cambrian explosion at 539 Ma produced almost every animal body plan alive today, from trilobites to the first chordates. Fish dominated the Devonian, amphibians and early reptiles the Carboniferous, and synapsids the Permian.
Radiometric dating. Rocks contain isotopes of uranium, potassium and lead that decay at known, clock-like rates, so measuring the parent and daughter isotopes left in a cooled crystal gives the time since it formed. Meteorites that never melted put the solar system at 4.567 billion years, and the oldest terrestrial minerals, zircons from the Jack Hills in Western Australia, reach 4.4 billion years.
Because 4.54 billion years drawn to scale would squash everything interesting into the right-hand edge: all of human history would be one pixel wide. Logarithmic spacing gives every order of magnitude the same width, so the Archean, the Cambrian explosion and Homo sapiens all stay readable on one bar. Switch to the linear views to see the true proportions and just how small the recent past is. The scale in force is always named under the bar.