43 events14 periods12 connectors
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{ "events": [ { "id": "event-solar-nebula", "info": "A cloud of gas and dust in the Milky Way begins collapsing under its own gravity, likely triggered by a nearby supernova shockwave. The rotating disk of material that forms will give rise to the Sun and all the planets, including Earth.", "name": "Solar Nebula Collapses", "time": { "unit": "mya", "value": 4600 }, "relates_to": "period-formation" }, { "id": "event-earth-accretion", "info": "Dust and rocky debris in the inner solar system collide and stick together through accretion, gradually building a molten proto-Earth. The young planet is a hellscape of magma oceans, with no solid surface, no atmosphere, and temperatures exceeding 2000°C.", "name": "Earth Begins to Form", "time": { "unit": "mya", "value": 4540 }, "relates_to": "period-hadean" }, { "id": "event-theia-impact", "info": "A Mars-sized body called Theia collides with the young Earth in a cataclysmic impact. The collision ejects vast amounts of debris into orbit, which coalesces to form the Moon. The impact also tilts Earth's axis, giving us seasons, and the Moon stabilizes this tilt over time.", "name": "Theia Impact and Moon Formation", "time": { "unit": "mya", "value": 4530 }, "relates_to": "period-hadean" }, { "id": "event-iron-catastrophe", "info": "Dense iron and nickel sink through the molten Earth to form a metallic core, while lighter silicates float upward to form the mantle. This differentiation releases enormous heat and establishes Earth's layered internal structure. The liquid iron core generates a magnetic field that will shield the planet from solar wind.", "name": "Iron Catastrophe and Core Formation", "time": { "unit": "mya", "value": 4500 }, "relates_to": "period-hadean" }, { "id": "event-magnetic-field", "info": "Convection currents in the liquid iron outer core generate a global magnetic field through the geodynamo effect. This magnetosphere deflects charged particles from the Sun, protecting the atmosphere from being stripped away and shielding the surface from harmful radiation.", "name": "Earth's Magnetic Field Established", "time": { "unit": "mya", "value": 4200 }, "relates_to": "period-hadean" }, { "id": "event-first-oceans", "info": "As Earth cools, water vapor released by volcanic outgassing condenses into torrential rains lasting millions of years, filling basins to form the first oceans. Comets and water-rich asteroids may also deliver additional water. Liquid water will prove essential for plate tectonics, weathering, and life.", "name": "First Oceans Form", "time": { "unit": "mya", "value": 4400 }, "relates_to": "period-hadean" }, { "id": "event-first-crust", "info": "The oldest known mineral grains—zircon crystals from Jack Hills, Australia—date to this time, indicating that patches of solid crust existed despite continued heavy bombardment. These ancient zircons also contain chemical signatures suggesting the presence of liquid water.", "name": "First Solid Crust Forms", "time": { "unit": "mya", "value": 4400 }, "relates_to": "period-hadean" }, { "id": "event-late-heavy-bombardment", "info": "A spike in asteroid and comet impacts batters the inner solar system, scarring the Moon and pummeling Earth. The bombardment may have been triggered by gravitational shifts in the outer planets. It delivers both destruction and volatile compounds, possibly contributing to Earth's water and organic chemistry.", "name": "Late Heavy Bombardment", "time": { "unit": "mya", "value": 4100 }, "relates_to": "period-hadean" }, { "id": "event-first-continents", "info": "The earliest fragments of continental crust form as lighter, silica-rich rocks begin to differentiate from the denser oceanic crust. The Acasta Gneiss in Canada, dating to about 4.0 billion years ago, is among the oldest known rocks on Earth's surface.", "name": "First Continental Crust", "time": { "unit": "mya", "value": 4000 }, "relates_to": "period-archean" }, { "id": "event-first-life", "info": "Chemical signatures in ancient rocks from Greenland suggest the presence of simple microbial life. Whether life originated at hydrothermal vents, in warm pools, or was delivered by meteorites remains debated, but Earth becomes a living planet remarkably early in its history.", "name": "Earliest Evidence of Life", "time": { "unit": "mya", "value": 3800 }, "relates_to": "period-archean" }, { "id": "event-stromatolites", "info": "Cyanobacteria build layered mineral structures called stromatolites in shallow seas. These microbes evolve oxygenic photosynthesis, beginning the slow transformation of Earth's atmosphere from one dominated by nitrogen, CO₂, and methane to one containing free oxygen.", "name": "Stromatolites and Photosynthesis", "time": { "unit": "mya", "value": 3500 }, "relates_to": "period-archean" }, { "id": "event-first-plate-tectonics", "info": "Evidence suggests that recognizable plate tectonics—with subduction zones, spreading ridges, and lateral plate motion—becomes established. Plate tectonics recycles carbon, builds mountains, creates new ocean floor, and drives volcanic activity, fundamentally regulating Earth's climate and chemistry.", "name": "Modern Plate Tectonics Begins", "time": { "unit": "mya", "value": 3200 }, "relates_to": "period-archean" }, { "id": "event-great-oxygenation", "info": "Oxygen produced by cyanobacteria accumulates in the atmosphere after overwhelming natural chemical sinks. Free oxygen rises from trace levels to roughly 2%, rusting dissolved iron in the oceans to form banded iron formations, triggering a mass die-off of anaerobic life, and creating Earth's ozone layer.", "name": "Great Oxygenation Event", "time": { "unit": "mya", "value": 2400 }, "relates_to": "period-proterozoic" }, { "id": "event-huronian-glaciation", "info": "The first major ice age in Earth's history, likely triggered by the Great Oxygenation Event. Rising oxygen destroys atmospheric methane—a potent greenhouse gas—causing temperatures to plummet. Ice sheets may have extended to the tropics in the earliest known Snowball Earth episode.", "name": "Huronian Glaciation", "time": { "unit": "mya", "value": 2300 }, "relates_to": "period-proterozoic" }, { "id": "event-boring-billion", "info": "Earth enters a period of remarkable environmental stability lasting roughly a billion years. Tectonic activity, atmospheric composition, and ocean chemistry remain relatively stable. While sometimes called 'boring,' eukaryotic cells evolve and diversify during this time.", "name": "The 'Boring Billion' Begins", "time": { "unit": "mya", "value": 1800 }, "relates_to": "period-proterozoic" }, { "id": "event-rodinia-assembly", "info": "Earth's landmasses converge to form the supercontinent Rodinia. Supercontinent cycles—assembly and breakup driven by mantle convection—profoundly influence climate, ocean circulation, and evolution by creating and destroying habitats on a global scale.", "name": "Supercontinent Rodinia Assembles", "time": { "unit": "mya", "value": 1100 }, "relates_to": "period-proterozoic" }, { "id": "event-rodinia-breakup", "info": "Rodinia rifts apart, opening new ocean basins. The breakup exposes fresh rock to chemical weathering, which draws CO₂ from the atmosphere and may contribute to the extreme glaciations that follow. New coastlines create shallow marine habitats.", "name": "Rodinia Breaks Apart", "time": { "unit": "mya", "value": 750 }, "relates_to": "period-proterozoic" }, { "id": "event-snowball-earth", "info": "Earth freezes almost entirely in at least two major glaciations: the Sturtian (~717 mya) and the Marinoan (~650 mya). Ice sheets extend to the equator, oceans freeze over, and surface life nearly perishes. Volcanic CO₂ eventually accumulates enough to trigger dramatic thawing.", "name": "Snowball Earth Glaciations", "time": { "unit": "mya", "value": 720 }, "relates_to": "period-snowball" }, { "id": "event-snowball-thaw", "info": "Volcanic CO₂ builds up under the ice until a runaway greenhouse effect rapidly melts the global ice sheets. The transition from icehouse to extreme greenhouse is violent—mega-hurricanes, torrential acid rain, and massive chemical weathering follow. The aftermath may set the stage for complex life.", "name": "Snowball Earth Thaws", "time": { "unit": "mya", "value": 635 }, "relates_to": "period-snowball" }, { "id": "event-ediacaran-fauna", "info": "The first large, complex multicellular organisms appear in the fossil record after the Snowball Earth thaw. These strange, quilted creatures—Dickinsonia, Charnia, Kimberella—represent a failed experiment or evolutionary stepping stone before the Cambrian Explosion.", "name": "Ediacaran Fauna Appears", "time": { "unit": "mya", "value": 575 }, "relates_to": "period-proterozoic" }, { "id": "event-cambrian-explosion", "info": "An extraordinary burst of evolution produces most major animal body plans within roughly 25 million years. Rising oxygen levels, ecological arms races, and the evolution of eyes and hard shells drive unprecedented diversification. Earth's biosphere transforms from microbial mats to complex ecosystems.", "name": "Cambrian Explosion", "time": { "unit": "mya", "value": 538.8 }, "relates_to": "period-phanerozoic" }, { "id": "event-first-land-plants", "info": "Simple plants move onto bare rock for the first time, beginning the transformation of Earth's continents. Over millions of years, plants create soil, alter weathering rates, draw down atmospheric CO₂, and build the foundation for terrestrial ecosystems.", "name": "Plants Colonize Land", "time": { "unit": "mya", "value": 470 }, "relates_to": "period-phanerozoic" }, { "id": "event-first-forests", "info": "The evolution of woody tissue allows trees like Archaeopteris to grow tall, forming the first forests. Forests profoundly alter Earth's carbon cycle, accelerate rock weathering, change rainfall patterns, and draw down atmospheric CO₂ so dramatically that they may contribute to the Late Devonian ice age.", "name": "First Forests Grow", "time": { "unit": "mya", "value": 385 }, "relates_to": "period-phanerozoic" }, { "id": "event-coal-swamps", "info": "Vast tropical swamp forests cover equatorial lowlands. Dead plant matter accumulates faster than it decomposes—fungi have not yet evolved the ability to break down lignin—burying enormous amounts of carbon that becomes coal. Oxygen levels reach 35%, the highest in Earth's history.", "name": "Carboniferous Coal Swamps", "time": { "unit": "mya", "value": 320 }, "relates_to": "period-phanerozoic" }, { "id": "event-pangaea-assembly", "info": "All major landmasses merge into the supercontinent Pangaea, stretching from pole to pole. A single landmass creates extreme continental climates with vast interior deserts, alters ocean circulation, and reduces coastal habitats—contributing to the Permian extinction.", "name": "Pangaea Fully Assembled", "time": { "unit": "mya", "value": 300 }, "relates_to": "period-pangaea" }, { "id": "event-permian-extinction", "info": "The worst mass extinction in Earth's history kills 96% of marine species and 70% of land species. Massive volcanism in Siberia (the Siberian Traps) releases CO₂ and toxic gases, triggering runaway warming, ocean acidification, and oxygen depletion. Earth takes 10 million years to recover.", "name": "The Great Dying", "time": { "unit": "mya", "value": 252 }, "relates_to": "period-phanerozoic" }, { "id": "event-pangaea-breakup", "info": "Pangaea rifts into Laurasia (north) and Gondwana (south), opening the central Atlantic Ocean. The breakup reshapes global ocean circulation, creates new coastlines and shallow seas, and ultimately produces the continental configuration we know today.", "name": "Pangaea Begins Breaking Apart", "time": { "unit": "mya", "value": 200 }, "relates_to": "period-pangaea" }, { "id": "event-atlantic-opens", "info": "The Atlantic Ocean expands as the Americas separate from Europe and Africa. Mid-ocean ridges produce new oceanic crust at rates of a few centimeters per year. The widening Atlantic fundamentally alters global ocean circulation and climate patterns.", "name": "Atlantic Ocean Widens", "time": { "unit": "mya", "value": 150 }, "relates_to": "period-modern-continents" }, { "id": "event-deccan-traps", "info": "Massive volcanic eruptions in what is now India produce the Deccan Traps—one of the largest volcanic features on Earth. These eruptions release vast quantities of CO₂ and sulfur dioxide, stressing ecosystems just before the Chicxulub asteroid delivers the final blow.", "name": "Deccan Traps Volcanism", "time": { "unit": "mya", "value": 66.5 }, "relates_to": "period-modern-continents" }, { "id": "event-chicxulub-impact", "info": "A 10-kilometer asteroid strikes the Yucatan Peninsula at 20 km/s, releasing energy equivalent to billions of nuclear weapons. The impact triggers global firestorms, a years-long 'impact winter,' acid rain, and the collapse of food chains. It eliminates 75% of all species, including all non-avian dinosaurs.", "name": "Chicxulub Asteroid Impact", "time": { "unit": "mya", "value": 66 }, "relates_to": "period-modern-continents" }, { "id": "event-india-asia-collision", "info": "The Indian subcontinent, having drifted north from Gondwana, collides with Asia. The collision begins raising the Himalayas and the Tibetan Plateau—a process still ongoing. This massive uplift alters global atmospheric circulation, monsoon patterns, and accelerates chemical weathering that draws down CO₂.", "name": "India Collides with Asia", "time": { "unit": "mya", "value": 50 }, "relates_to": "period-modern-continents" }, { "id": "event-antarctic-glaciation", "info": "As Antarctica separates from South America, the Antarctic Circumpolar Current forms, thermally isolating the southern continent. Combined with declining CO₂ levels, this triggers the growth of a permanent ice sheet on Antarctica, marking the transition to the current icehouse climate.", "name": "Antarctic Ice Sheet Forms", "time": { "unit": "mya", "value": 34 }, "relates_to": "period-icehouse" }, { "id": "event-panama-closes", "info": "The land bridge connecting North and South America completes, severing the connection between the Atlantic and Pacific oceans. This redirects ocean currents, strengthens the Gulf Stream, and increases moisture delivery to the Arctic—possibly helping trigger Northern Hemisphere glaciation.", "name": "Isthmus of Panama Closes", "time": { "unit": "mya", "value": 3 }, "relates_to": "period-icehouse" }, { "id": "event-ice-ages-begin", "info": "Earth enters a pattern of rhythmic glaciations driven by Milankovitch cycles—subtle variations in Earth's orbit and axial tilt. Ice sheets advance and retreat roughly every 100,000 years. These glacial-interglacial cycles shape landscapes, drive evolution, and eventually provide the backdrop for human emergence.", "name": "Quaternary Ice Ages Begin", "time": { "unit": "mya", "value": 2.6 }, "relates_to": "period-icehouse" }, { "id": "event-last-glacial-max", "info": "Ice sheets reach their greatest extent of the current ice age, covering much of North America and northern Europe with ice up to 3 kilometers thick. Sea levels drop 120 meters, exposing land bridges and reshaping coastlines. Global temperatures average about 6°C colder than today.", "name": "Last Glacial Maximum", "time": { "unit": "years-ago", "value": 20000 }, "relates_to": "period-icehouse" }, { "id": "event-holocene-begins", "info": "The current interglacial period begins as ice sheets rapidly retreat. Sea levels rise, forests expand, and the stable, warm climate enables the development of agriculture and human civilization. The Holocene's climate stability is exceptional compared to the preceding glacial period.", "name": "Holocene Warm Period Begins", "time": { "unit": "years-ago", "value": 11700 }, "relates_to": "period-holocene" }, { "id": "event-sahara-green", "info": "The Sahara Desert is lush and green, covered in grasslands, lakes, and rivers supporting hippos, crocodiles, and human communities. Orbital changes strengthen the African monsoon. By 5,500 years ago, the monsoon weakens and the Sahara desiccates rapidly—one of the most dramatic recent landscape transformations.", "name": "Green Sahara Period", "time": { "unit": "years-ago", "value": 9000 }, "relates_to": "period-holocene" }, { "id": "event-anthropocene-proposed", "info": "Scientists propose that human activity has become the dominant geological force on Earth. Nuclear fallout, plastic pollution, concrete, chicken bones, and CO₂ from fossil fuels leave a permanent mark in the geological record. Whether formally adopted or not, the concept captures humanity's planetary-scale impact.", "name": "The Anthropocene", "time": { "unit": "ce", "value": 1950 }, "relates_to": "period-holocene" }, { "id": "event-future-supercontinent", "info": "Plate tectonics will reassemble the continents into a new supercontinent, sometimes called Pangaea Ultima or Amasia. The Atlantic Ocean closes as the Americas drift back toward Europe and Africa. The resulting supercontinent will create extreme climates and reshape ocean circulation entirely.", "name": "Next Supercontinent (Pangaea Ultima)", "time": { "unit": "ce", "value": 250000000 }, "relates_to": "period-far-future" }, { "id": "event-oceans-evaporate", "info": "As the Sun gradually brightens (roughly 1% every 100 million years), Earth's surface temperatures rise to a point where the oceans begin evaporating. Water vapor—a potent greenhouse gas—accelerates warming in a runaway feedback loop. Earth begins its transformation toward a Venus-like state.", "name": "Oceans Begin to Evaporate", "time": { "unit": "ce", "value": 1000000000 }, "relates_to": "period-far-future" }, { "id": "event-plate-tectonics-end", "info": "Earth's interior cools sufficiently that mantle convection weakens and plate tectonics grinds to a halt. Without tectonic recycling, the carbon cycle breaks down, volcanic CO₂ replenishment stops, and the geological engine that regulated Earth's climate for billions of years falls silent.", "name": "Plate Tectonics Ceases", "time": { "unit": "ce", "value": 1500000000 }, "relates_to": "period-far-future" }, { "id": "event-magnetic-field-fades", "info": "As the core solidifies and convection slows, Earth's magnetic field weakens and eventually disappears. Without the magnetosphere, the solar wind gradually strips away the atmosphere, much as it did to Mars billions of years ago.", "name": "Magnetic Field Weakens", "time": { "unit": "ce", "value": 2000000000 }, "relates_to": "period-far-future" }, { "id": "event-sun-red-giant", "info": "The Sun exhausts its hydrogen fuel and expands into a red giant, engulfing Mercury and Venus. Whether Earth is consumed or merely scorched depends on orbital dynamics, but either way, all traces of Earth's geological and biological history on the surface are erased.", "name": "Sun Becomes a Red Giant", "time": { "unit": "ce", "value": 5000000000 }, "relates_to": "period-far-future" } ], "periods": [ { "id": "period-formation", "info": "The Sun and planets form from a collapsing cloud of gas and dust called the solar nebula. Rocky material in the inner disk accretes into the terrestrial planets—Mercury, Venus, Earth, and Mars—through increasingly violent collisions.", "name": "Solar System Formation", "endTime": { "unit": "mya", "value": 4540 }, "startTime": { "unit": "mya", "value": 4600 } }, { "id": "period-hadean", "info": "Named for Hades, the Greek underworld, reflecting its hellish conditions. Earth is molten, bombarded by asteroids, and lacks a stable surface. Yet during this violent period, the core differentiates, the Moon forms, the magnetic field ignites, the first oceans condense, and the oldest mineral grains crystallize.", "name": "Hadean Eon", "endTime": { "unit": "mya", "value": 4000 }, "startTime": { "unit": "mya", "value": 4540 } }, { "id": "period-archean", "info": "Earth stabilizes enough for life to emerge. The first continents form, plate tectonics begins, and prokaryotic life dominates. Cyanobacteria evolve photosynthesis, slowly beginning to oxygenate the atmosphere. The Archean Earth has a faint Sun, a reducing atmosphere, and green-tinged seas rich in dissolved iron.", "name": "Archean Eon", "endTime": { "unit": "mya", "value": 2500 }, "startTime": { "unit": "mya", "value": 4000 } }, { "id": "period-proterozoic", "info": "The longest eon sees transformative changes: the Great Oxygenation Event, the first Snowball Earth episodes, the evolution of eukaryotic and then multicellular life, and the assembly and breakup of supercontinents. By its end, the Ediacaran fauna heralds the coming explosion of complex life.", "name": "Proterozoic Eon", "endTime": { "unit": "mya", "value": 538.8 }, "startTime": { "unit": "mya", "value": 2500 } }, { "id": "period-snowball", "info": "Earth freezes almost entirely in at least two catastrophic glaciations. Ice sheets reach the equator, oceans freeze over, and life clings on in refugia near volcanic vents and thin ice. The dramatic thawing may have triggered conditions that enabled the evolution of complex animal life.", "name": "Snowball Earth Episodes", "endTime": { "unit": "mya", "value": 635 }, "startTime": { "unit": "mya", "value": 720 } }, { "id": "period-phanerozoic", "info": "The eon of 'visible life' encompasses all of complex life's history. From the Cambrian Explosion to the present, five mass extinctions punctuate a story of increasing biological complexity. Continents drift, climates swing between icehouse and greenhouse, and life transforms Earth's surface again and again.", "name": "Phanerozoic Eon", "startTime": { "unit": "mya", "value": 538.8 } }, { "id": "period-pangaea", "info": "Earth's landmasses converge into a single supercontinent stretching from pole to pole, surrounded by the global ocean Panthalassa. Pangaea's formation and breakup drive mass extinctions, create new ocean basins, and redistribute life across the globe.", "name": "Pangaea Supercontinent", "endTime": { "unit": "mya", "value": 175 }, "startTime": { "unit": "mya", "value": 335 } }, { "id": "period-modern-continents", "info": "Pangaea fragments into the continents we recognize. The Atlantic opens, India races north toward Asia, Australia separates from Antarctica. Mountain chains rise where plates collide—the Andes, Alps, and Himalayas. Each continental rearrangement reshapes ocean currents and global climate.", "name": "Modern Continents Take Shape", "endTime": { "unit": "mya", "value": 34 }, "startTime": { "unit": "mya", "value": 175 } }, { "id": "period-icehouse", "info": "Earth transitions from the warm Eocene greenhouse into a long cooling trend. Antarctic ice sheets form first, followed by Northern Hemisphere glaciation. The Quaternary ice ages bring rhythmic glacial-interglacial cycles that carve landscapes, reshape coastlines, and drive the evolution of cold-adapted species and humans.", "name": "Icehouse Earth", "endTime": { "unit": "years-ago", "value": 11700 }, "startTime": { "unit": "mya", "value": 34 } }, { "id": "period-holocene", "info": "The current warm interglacial period. Stable, mild climate enables agriculture, civilization, and explosive human population growth. In just 12,000 years—a geological eyeblink—humans transform the planet's surface, atmosphere, and biosphere more profoundly than any force since the asteroid that killed the dinosaurs.", "name": "Holocene Epoch", "startTime": { "unit": "years-ago", "value": 11700 } }, { "id": "period-atmosphere-evolution", "info": "Earth's atmosphere transforms from a primordial mix of CO₂, nitrogen, and water vapor to one rich in nitrogen and oxygen. Volcanic outgassing builds the early atmosphere, photosynthesis adds oxygen, the ozone layer forms, and by the Devonian, oxygen levels approach modern values.", "name": "Atmospheric Evolution", "endTime": { "unit": "mya", "value": 400 }, "startTime": { "unit": "mya", "value": 4400 } }, { "id": "period-supercontinent-cycle", "info": "Earth's continents repeatedly assemble into supercontinents and break apart in cycles lasting 300–500 million years. Known supercontinents include Kenorland (~2.7 Ga), Columbia/Nuna (~1.8 Ga), Rodinia (~1.1 Ga), and Pangaea (~300 Ma). Each cycle reshapes climate, ocean circulation, and the trajectory of life.", "name": "Supercontinent Cycles", "startTime": { "unit": "mya", "value": 2700 } }, { "id": "period-mass-extinctions", "info": "Five catastrophic events punctuate the Phanerozoic, each eliminating 70–96% of species. Caused by volcanism, asteroid impacts, glaciation, and ocean chemistry changes, they repeatedly reshape the trajectory of life—destroying dominant groups and opening opportunities for new ones.", "name": "The Big Five Mass Extinctions", "endTime": { "unit": "mya", "value": 66 }, "startTime": { "unit": "mya", "value": 445 } }, { "id": "period-far-future", "info": "Earth's future is governed by the Sun's increasing luminosity. Over hundreds of millions of years, rising temperatures evaporate the oceans, plate tectonics ceases, the magnetic field fades, and the atmosphere is lost. Earth's story as a habitable world—spanning roughly 4.5 billion years—eventually ends.", "name": "Earth's Far Future", "endTime": { "unit": "ce", "value": 5500000000 }, "startTime": { "unit": "ce", "value": 100000000 } } ], "connectors": [ { "id": "conn-formation-hadean", "toId": "period-hadean", "type": "defined", "fromId": "period-formation", "metadata": { "note": "Accretion produces a molten proto-Earth" } }, { "id": "conn-hadean-archean", "toId": "period-archean", "type": "defined", "fromId": "period-hadean", "metadata": { "note": "Earth cools and stabilizes, enabling life" } }, { "id": "conn-archean-proterozoic", "toId": "period-proterozoic", "type": "defined", "fromId": "period-archean", "metadata": { "note": "Oxygenation transforms the planet" } }, { "id": "conn-proterozoic-snowball", "toId": "period-snowball", "type": "defined", "fromId": "period-proterozoic", "metadata": { "note": "Continental breakup and weathering trigger extreme glaciation" } }, { "id": "conn-snowball-phanerozoic", "toId": "period-phanerozoic", "type": "defined", "fromId": "period-snowball", "metadata": { "note": "Post-glacial conditions enable complex life" } }, { "id": "conn-phanerozoic-pangaea", "toId": "period-pangaea", "type": "defined", "fromId": "period-phanerozoic", "metadata": { "note": "Continental drift assembles Pangaea during the Phanerozoic" } }, { "id": "conn-pangaea-modern", "toId": "period-modern-continents", "type": "defined", "fromId": "period-pangaea", "metadata": { "note": "Pangaea fragments into today's continents" } }, { "id": "conn-modern-icehouse", "toId": "period-icehouse", "type": "defined", "fromId": "period-modern-continents", "metadata": { "note": "Continental rearrangement drives global cooling" } }, { "id": "conn-icehouse-holocene", "toId": "period-holocene", "type": "defined", "fromId": "period-icehouse", "metadata": { "note": "Glacial retreat begins the current warm period" } }, { "id": "conn-atmosphere-to-phanerozoic", "toId": "period-phanerozoic", "type": "defined", "fromId": "period-atmosphere-evolution", "metadata": { "note": "Oxygenated atmosphere enables complex life on land" } }, { "id": "conn-supercontinent-pangaea", "toId": "period-pangaea", "type": "undefined", "fromId": "period-supercontinent-cycle", "metadata": { "note": "Pangaea is the most recent in a recurring cycle" } }, { "id": "conn-extinctions-phanerozoic", "toId": "period-mass-extinctions", "type": "undefined", "fromId": "period-phanerozoic", "metadata": { "note": "Mass extinctions repeatedly reset the trajectory of complex life" } } ] }