Geological Periods
540 million years in twelve chapters
Geologists divide the last 539 million years, the Phanerozoic Eon, into twelve periods. Each one opens a different world: new continents, new climates, new animals. Pick a period to see its reconstructed map, what lived there, and the data behind it.
What Is the Geological Time Scale?
The geological time scale is the system scientists use to describe the timing and relationships of events in Earth's history. It divides deep time into a hierarchy of intervals, eons, eras, periods, and epochs, each defined by distinctive changes in the rock record: mass extinctions, the appearance of new life forms, or major shifts in climate and geography.
The boundaries between these divisions are not arbitrary. They mark real, often dramatic events in Earth's story, the end of the Cretaceous period, for example, is defined by the asteroid impact that wiped out the non-avian dinosaurs 66 million years ago.
The interactive map covers the last 540 million years, the Phanerozoic Eon, when complex animal life first appeared. Use the time slider to jump between geological periods.
Paleozoic
- Cambrian 538.8–485.4 Ma The Cambrian explosion: almost every animal body plan appears in the sea. Open on the map →
- Ordovician 485.4–443.8 Ma Seas teem with life, the first plants creep ashore, and an ice age ends it. Open on the map →
- Silurian 443.8–419.2 Ma Life recovers, vascular plants and arthropods move onto land, and fish get jaws. Open on the map →
- Devonian 419.2–358.9 Ma The Age of Fishes: the first forests and the first four-legged animals. Open on the map →
- Carboniferous 358.9–298.9 Ma Coal swamps, giant insects and the assembly of Pangea. Open on the map →
- Permian 298.9–251.9 Ma Pangea at its fullest, ending in the Great Dying, the worst extinction ever. Open on the map →
Mesozoic
- Triassic 251.9–201.4 Ma Life rebuilds after the Great Dying, and the first dinosaurs and mammals appear. Open on the map →
- Jurassic 201.4–145 Ma Dinosaurs rule, the Atlantic opens, and the first birds take flight. Dinosaurs on our map: 4 Open on the map →
- Cretaceous 145–66 Ma Peak dinosaurs, flowering plants and high seas, ending with the Chicxulub impact. Dinosaurs on our map: 9 Open on the map →
Cenozoic
- Paleogene 66–23.03 Ma Mammals take over, India hits Asia, and a hothouse turns into an icehouse. Open on the map →
- Neogene 23.03–2.58 Ma Grasslands spread, the Mediterranean dries out, and our ancestors walk upright. Open on the map →
- Quaternary 2.58–present Ice ages, mammoths and the spread of modern humans around the globe. Open on the map →
How long each period lasted
How much of Earth was dry land?
Before the Phanerozoic
The Precambrian, everything before 541 million years ago, represents about 88% of Earth's entire history. During this vast span, Earth cooled from a molten ball, the first oceans and atmosphere formed, life first appeared (around 3.5 billion years ago), and several earlier supercontinents assembled and broke apart.
Earth's history · About & data sources
Keep exploring
- Earth's history4.5 billion years in one story, from a molten planet to today.
- Plate tectonicsHow plates move, collide and build mountains and oceans.
- LearnArticles on countries, dinosaurs and supercontinents.
- FAQQuick answers about Pangea and the map.
- About & data sourcesWhere the reconstructions and fossil data come from.