Timeline of Earth's History
The physical history of Earth, from its formation about 4.54 billion years ago through changing continents, oceans and climates to the start of the Holocene about 11,700 years ago.
- Category
- Natural Sciences
- Events
- 22 events c. 4.54 billion years ago – c. 9700 BCE
- Generated
- by gpt-6-astra
c. 4.54 billion years ago: Earth assembles from the solar nebula
Dust and rocky bodies orbiting the young Sun accumulated into Earth. Heat from impacts and radioactive decay helped separate the planet into a metallic core and a rocky mantle; the age estimate comes chiefly from radiometric dating of meteorites.
Wikipediac. 4.5 billion years ago: A giant impact helps form the Moon
The leading explanation for the Moon's origin is a collision between the young Earth and a large planetary body. Debris entered orbit and assembled into the Moon, although the timing and details of the impact remain under study.
Wikipediac. 4.4 billion years ago: Zircons preserve evidence of an early crust
Zircon crystals later preserved in Western Australia recorded conditions on the young Earth. Their chemistry suggests interaction between crustal rocks and liquid water, evidence that a habitable surface may have developed much earlier than surviving rock formations imply.
Wikipediac. 4.03 billion years ago: Ancient crust survives in the Acasta gneiss
Rocks now exposed in northwestern Canada formed from some of Earth's earliest surviving crust. Later metamorphism altered them, but zircon dating preserved a record of crust formation that largely disappeared elsewhere through melting, erosion and tectonic recycling.
Wikipediac. 2.45 billion years ago: Oxygen begins accumulating in the atmosphere
Oxygen produced by photosynthetic microbes began accumulating persistently in the atmosphere during the Great Oxidation Event. The transition transformed surface chemistry and the cycling of elements; it unfolded over an extended interval rather than in a single burst.
Wikipediac. 2.4–2.1 billion years ago: Repeated glaciations mark the early Proterozoic
Glacial deposits in the Huronian succession recorded repeated episodes of severe cooling. The interval overlapped rising atmospheric oxygen, which may have weakened methane greenhouse warming, although the relationship between oxygenation and individual glaciations remains debated.
Wikipediac. 1.8 billion years ago: Continents assemble into Columbia
Continental collisions assembled a supercontinent commonly called Columbia or Nuna. Reconstructions differ in detail, but matching geological belts record a major phase of continental assembly long before the better-known Pangaea.
Wikipediac. 1.3–0.9 billion years ago: Rodinia brings continental blocks together
Mountain-building collisions joined much of Earth's continental crust into Rodinia. Its later fragmentation rearranged ocean basins and continental margins, although the positions of some landmasses remain uncertain.
Wikipediac. 717 million years ago: Sturtian ice spreads toward the tropics
An exceptionally long glaciation left deposits on continents that lay near the equator. The evidence became central to the Snowball Earth hypothesis, in which ice covered most or all of the planet's surface, with the extent of open water still debated.
Wikipediac. 635 million years ago: Marinoan glaciation ends
A widespread glaciation ended near the close of the Cryogenian Period. Carbonate rocks deposited above glacial sediments recorded the transition out of extreme cold; the onset and duration of the preceding glaciation remained less securely constrained than its end.
Wikipediac. 335 million years ago: Pangaea begins assembling
Collisions between major landmasses began assembling Pangaea, a supercontinent surrounded by the global ocean Panthalassa. The resulting mountain belts and vast continental interior changed drainage, ocean circulation and regional climates.
Wikipediac. 320 million years ago: Ice sheets expand across southern Pangaea
Large ice sheets spread across parts of Gondwana during the late Paleozoic ice age. Their repeated growth and retreat changed sea levels, leaving alternating marine and terrestrial deposits in tropical regions far from the ice.
Wikipediac. 200–175 million years ago: Pangaea breaks apart and the Atlantic opens
Rifting separated major parts of Pangaea and initiated the opening of the central Atlantic Ocean. Continental breakup continued over tens of millions of years, gradually producing the geography of the modern ocean basins.
Wikipediac. 66 million years ago: Chicxulub impact disrupts the global environment
An asteroid struck what is now Mexico's Yucatán Peninsula. Ejected dust and aerosols disrupted sunlight and climate, and the impact coincided with the mass extinction that ended the Cretaceous Period.
Wikipediac. 56 million years ago: A carbon release drives rapid warming
During the Paleocene–Eocene Thermal Maximum, a large addition of carbon to the ocean and atmosphere accompanied rapid global warming and ocean acidification. The episode became a geological example of the consequences of a major disturbance to the carbon cycle.
Wikipediac. 50 million years ago: India collides with Asia
The Indian continental plate collided with Eurasia, initiating the mountain-building history of the Himalayas. Estimates of when collision began vary, and the mountains rose through a prolonged process that continued as the plates converged.
Wikipediac. 34 million years ago: Antarctica develops a continental ice sheet
Global cooling near the Eocene–Oligocene boundary accompanied the growth of a large Antarctic ice sheet. Falling atmospheric carbon dioxide and changes in ocean gateways contributed to the transition from a warmer world toward an icehouse climate.
Wikipediac. 5.96 million years ago: Restricted exchange transforms the Mediterranean
Restricted connections with the Atlantic helped trigger the Messinian salinity crisis. Thick salt deposits accumulated as the Mediterranean lost water through evaporation; the extent and timing of basin desiccation remain subjects of research.
Wikipediac. 5.33 million years ago: Atlantic water refills the Mediterranean
The Mediterranean reconnected with the Atlantic at the end of the Messinian salinity crisis. Geological evidence supports a major flooding event through the Gibraltar gateway, although the speed and details of the refilling remain debated.
Wikipediac. 2.58 million years ago: The Quaternary brings recurring northern ice sheets
The Quaternary Period began during an interval of expanding Northern Hemisphere glaciation. Repeated glacial and interglacial cycles subsequently reshaped landscapes, altered sea levels and repeatedly exposed land bridges.
Wikipediac. 26,500–19,000 years ago: Ice sheets reach their last maximum
Continental ice sheets reached their greatest extent of the last glacial cycle during the Last Glacial Maximum. Lower sea levels exposed continental shelves, while cold, dry conditions shifted ecosystems far beyond the ice margins.
Wikipediac. 9700 BCE: The Holocene begins as glacial conditions retreat
The end of the Younger Dryas cold interval marked the beginning of the Holocene Epoch. Warming and continued ice-sheet retreat reshaped coasts and ecosystems during the interglacial in which agriculture and urban societies developed.
Wikipedia