The Rodinia supercontinent triggered a global ice age when it broke 750 million years ago

The formation and breakup of Pangaea altered Earth’s geology and biodiversity

Coming from the Greek words for “all” (pan) and “Earth” (gaia), the supercontinent existed from about 320 million to 195 million years ago. The tectonic activity that split Pangaea into today’s continents may one day bring the continents back together, forming Pangaea Proxima.

Ice ages are periods of glaciation that last tens of millions of years

During these periods, Earth grows cold and is covered in massive continental ice sheets. Scientists have outlined at least five major ice ages, which result from the alignment of complex factors, like the flow of ocean currents and the movement and location of tectonic plates.

The theory of plate tectonics first emerged from the theory of continental drift

German meteorologist Alfred Wegener proposed that the continents were all one giant landmass in the past, which he named Pangaea. Despite geological and climate evidence suggesting continental movement, his theory was dismissed until the 1960s.

Carbon dioxide acts as a 'control knob' for Earth's climate

Although Earth's ice ages were primarily triggered by slow changes in the planet's orbit—known as Milankovitch cycles—these changes do not explain the extreme temperature swings during glacial periods. Carbon dioxide acts as a feedback mechanism, intensifying both cooling during ice ages and warming during their ends by reinforcing the initial changes sparked by orbital shifts.

200 million years of tectonic plate movement

The Earth's internal forces have continuously pushed and reshaped how the planet's land masses are arranged. From one supercontinent hundreds of millions of years ago, to present day, the Earth has looked dramatically different throughout the...

Earth has shifted between extreme warming and cooling phases for 500 million years

Earth is in an interglacial period of the Quaternary glaciation, resulting in receding glaciers and mild temperatures. However, today's warming trend is occurring much faster than previous warming periods in the climate record.

Underwater volcanoes significantly contributes to marine extinctions during the Triassic period

An analysis of ocean basins in the Tibetan Plateau helped identify three major periods of volcanism—250-248, 233-231, and 210-208 million years ago—which released significant amounts of greenhouse gases, altering ocean chemistry. The low-oxygen conditions may help explain half of Earth's Triassic extinctions.

Dinosaurs emerged 245 million years ago when Earth’s continents were still conjoined

Once the supercontinent split apart, dinosaurs evolved into thousands of species as they adapted to their changing environments. All non-avian dinosaurs went extinct about 66 million years ago following an asteroid impact, while avian dinosaurs evolved into today’s birds.

The 300-million-year period where Earth looked like a snowball

Life has existed on Earth for at least 3 billion years, but the planet has not always looked like it does today. Rather than the blues and greens of our modern globe, for a 300 million-year period, the Earth was covered in ice and snow, from the poles to the equator. Surprisingly, life was thriving at the time.

Travel through deep time with this interactive Earth

Explore key moments in Earth’s transformative history as continents drift and climate fluctuates over 4.6 billion years. The Smithsonian presents a series of interactive snapshots of the earth. From its toddler years during the Hadean period, when its surface was mostly molten, to the mostly unidentifiable landmasses of the future earth, 100 million years from now.

The theory of plate tectonics was not initially accepted until evidence became undeniable

Alfred Wegener proposed continental drift—the movement of large landmasses—in 1912 to explain why similar rock layers, plant and animal fossils, and glacial deposits were found on continents that were then unconnected. In the early 1960s, this was combined with evidence of seafloor spreading, mantle convection in Earth's interior, and earthquake and volcanic data outlining plate boundaries to produce the accepted theory.

Changes in Earth's orbital cycles influence the timing of ice ages

These cycles include changes in Earth's orbit shape, tilt, and wobble, all of which alter how much solar energy different parts of Earth receive over time. Due to orbital eccentricity, summers in the Northern Hemisphere last about 4.5 days longer than winters.

The Antarctic Circumpolar Current is Earth's most powerful ocean current and carries more than 100 times the combined flow of all Earth's rivers.

Supermountains the size of the continental US may have sparked complex life on Earth

Geological records show that the Nuna and the Transgondwanan Supermountains existed around the same time as two major jumps in species complexity on the planet: the rise of large organisms and the Cambrian explosion, respectively. Researchers believe that the erosion of these mountains deposited major nutrients into the oceans and boosted oxygen levels, both of which supported more complex species.

In 2025, UK scientists began studying climate data from a 1.5-million-year-old ice core

The Antarctica sample will be melted and analyzed in Cambridge to learn about prehistoric environmental conditions. Researchers hope the ice core reveals how Earth's glacial cycles shifted dramatically around 800,000 years ago.

Rising sea levels due to climate change may be slowing Earth's rotation

A 2024 PNAS study found that from 2000 to 2020, the length of a day increased at a rate of 1.33 milliseconds per century, an unprecedented amount in the 3.6 million years of day-length changes reconstructed from an analysis of benthic foraminifera fossils. Researchers suggest the slowing comes from changing ice sheets redistributing planetary mass.

Watch 1 billion years of tectonic plate movement in 40 seconds

Researchers at the University of Sydney developed the model, incorporating changing plate boundaries rather than just moving continents, to better understand the changes to biological and climatic systems throughout Earth’s history.

What did Earth look like when dinosaurs roamed?

The face of the Earth isn’t remotely the same as when the dinosaurs ruled the roost. The passing of millions of years, plate tectonics, and a spotty track record with asteroid collisions have changed the planet’s surface. Use this interactive globe to see what the Earth looked like millions of years ago.

About 66 million years ago, an asteroid larger than Mount Everest struck Earth off the coast of the Yucatán Peninsula and wiped out at least 75% of all species, including nearly all dinosaurs.

Scientists can determine Earth's past climate conditions by analyzing air trapped in microscopic bubbles within ice cores—columns of compressed snow layers that build up over hundreds of thousands of years.

The cycling of carbon via tectonic activity may have facilitated life on Earth

Plates sinking into Earth’s mantle pull carbon from the surface, helping stabilize the atmosphere and climate by removing greenhouse gases from volcanic eruptions. At the same time, magma is a significant contributor of heavy metals and other crucial minerals for life to the surface.

Records of Earth's magnetic field on the seafloor validated plate tectonics

Matching glacial, fossil, and rock records, mountain ranges, and continental shapes across oceans was insufficient evidence for continental drift. Precise measurements of magnetic minerals on the ocean floor revealed seafloor spreading, which could only be explained by moving landmasses.

Continental drift is supported by matching evidence across disconnected continents

Mesosaurus fossils are found in South America and Africa, but these freshwater creatures could not have travelled across the ocean between continents. Rock layers in the Appalachian Mountains match those seen in Europe, indicating that the mountain belts were once connected.

Large igneous provinces are regions of massive ancient volcanic activity

Linked to some mass extinction events on Earth, LIPs contain significant amounts of igneous rock formed by the release of lava and gases over millions of years. India's Deccan Traps and the Siberian Traps are prominent examples of LIPs, whose climate-related impacts can serve as models for analyzing modern climate change.

Earth’s major tectonic plates make up 95% of its surface

Tectonic plates are pieces of Earth’s lithosphere, which consists of the crust and the solid, upper layer of the mantle. Segments of major plates can break and form minor or microplates, whose total number varies based on ongoing geological activity.

Surface ocean currents are primarily driven by wind, tides, and Earth's rotation, while deep-ocean currents are driven by differences in temperature and salt concentration.

Just as landmasses have been divided into distinct nations, the world ocean has been divided into multiple oceans for various geographical, practical, and scientific reasons.

The missing continent that took 375 years to find

It took scientists 375 years to discover the eighth continent of the world, which had been hiding in plain sight all along. But mysteries still remain.

Humans were forced to adapt to survive a supervolcano eruption 74,000 years ago

The Toba supereruption ejected 2800 cubic kilometers of ash, resulting in global cooling from blocked sunlight and acid rain. Archaeological sites show that humans developed bow-and-arrow technology to survive in arid conditions by fishing in seasonal waterholes.

Climate models have predicted sea level rise almost perfectly since the 1990s

The rise in sea levels is primarily due to melting ice in Greenland and Antarctica, and predicted levels have been confirmed accurate by satellite observations. Ocean currents influence regional variations in sea level rise, which are expected to accelerate.

There have been five mass extinction events in Earth’s history

Each extinction event has resulted in the loss of at least 70% of Earth’s species at the time of the event, often due to significant changes in global temperatures. The most recent event occurred 66 million years ago and wiped out all non-avian dinosaurs.

Rapid environmental changes are exacerbating natural extinction processes

Human activities behind climate change, habitat destruction, pollution, and overhunting have resulted in extinction rates up to 1,000 times greater than normal, triggering massive biodiversity loss. This has led scientists to refer to the current geological age as the Anthropocene era, in which humans are the dominant force shaping nature.

Scientists determined that tectonic plates moved the ocean floor by observing symmetric patterns of magnetic stripes on opposite sides of underwater volcano systems, which could only result from seafloor spreading.

Some tectonic plates move faster than their underlying convection currents

Like a chain slipping off a ledge, as tectonic plates sink, their weight can pull the rest of the trailing plate forward, accelerating their movement. Plates can also break apart and fall, creating a suction effect that drives movement, resembling leaves following a passing car.

Studies show the asteroid that killed the dinosaurs was from the outer asteroid belt

Isotopic evidence confirms the rock was a carbon-rich asteroid, likely born beyond Jupiter and later knocked into Earth's path after billions of years of orbital drift and gravitational nudges. Its path spanned over 4 billion years and ended in the extinction of 75% of life, including all nonavian dinosaurs.

When oceanic plates sink beneath tectonic ones, they can generate magma

At converging oceanic-continental plate boundaries, the subduction of the oceanic plate introduces seawater that reduces the melting temperature of the overlying mantle. This causes it to melt into less dense magma, which can rise to fuel more volcanic activity.

A medieval warm period reshaped agriculture across parts of the world

Between 750 and 1350 CE, some regions experienced temperatures that rivaled or exceeded late-20th-century averages, likely due to shifts in El Niño–La Niña cycles. The warmer, wetter climate in Europe and northeast North America boosted agriculture, while causing droughts elsewhere.

Humans have existed for just 0.004% of Earth’s history

Born from the remains of the molecular cloud that birthed the sun, Earth experienced planetary-scale collisions, asteroid impacts, and lava seas. Life became possible after the planet cooled and formed a thin crust, atmosphere, and oceans.

The resulting climate change, not the asteroid impact itself, killed most dinosaurs

Although the Chicxulub impact caused widespread destruction through earthquakes and tsunamis, the subsequent nuclear winter, acid rain, and eventual greenhouse warming drove mass extinction. Roughly 70% of species, including all non-avian dinosaurs, went extinct.

Supervolcanoes can eject enough material to fill one-fourth of the Grand Canyon

Although extremely rare, their released material can trigger winters by blocking the sun and cooling the Earth’s surface for years. The Toba supereruption 74,000 years ago disrupted food chains and reduced the human population to a few thousand.

Mid-ocean ridges are underwater volcano systems where tectonic plates diverge

New ocean crust is formed at these ridges as magma rises from Earth’s mantle and fills the space between the spreading plates. The speed of divergence influences ridge shape, with slow spreads forming rugged valleys and fast spreading creating smooth, wide slopes.

Arctic permafrost may store twice as much carbon as the entire atmosphere

Rising greenhouse gas concentrations are expected to continue to increase average global temperatures and threaten to thaw ground that has been frozen for thousands of years. The release of greenhouse gases from remnant organic matter would exacerbate the greenhouse effect, creating a positive feedback loop.

Discovering how the dinosaurs went extinct may have helped avert nuclear war

This NPR Throughline episode explains how the 1980 discovery that an asteroid-driven dust cloud killed the dinosaurs inspired Cold War scientists' fears of "nuclear winter"—a sunlight-blocking aftermath of nuclear war that may have discouraged leaders from launching one.

Remnants of another planet that helped form the moon may be beneath Earth's surface

Large mantle structures beneath Africa and the Pacific Ocean may be the buried remains of Thea, a large Mars-sized planet that collided with Earth. The theory is supported by isotopic evidence from volcanic and lunar rocks.

How glaciers melt

Greenland and Antarctica are home to most of the world's glacial ice, including its only two ice sheets, making them areas of particular interest to scientists. Watch this three-minute video to learn why understanding them is not just interesting, but crucial to our near-term adaptability and our long term survival in a changing world.

An analysis of fossilized reefs from northern Africa and Germany suggests that shallow water corals and photosynthetic algae formed the mutualistic partnership seen today between 419 and 359 million years ago.

Dinosaurs’ feathers and greater metabolism helped them survive polar conditions

Studies of dinosaur footprints alongside ice-deposited rock fragments indicate that early dinosaurs adapted to cold weather before the volcanic winters of the Triassic-Jurassic extinction event. These geological events helped dinosaurs to flourish by wiping out their amphibious competitors.

Dinosaurs would likely still roam Earth if the Chicxulub asteroid had hit elsewhere

Some scientists argue that the asteroid's impact would have been less severe if it had struck the ocean instead of shallow seas. In this scenario, small dinosaurs might have become urban survivors, living in cities alongside humans, much like pigeons or rats do today.

Ancient sunken plates may influence mantle convection and surface motion

Research suggests sunken tectonic plates can collide, assemble, and break apart to form structures called large low-velocity provinces. LLVPs can significantly enrich rising magma plumes with elements commonly seen on Earth’s surface.

If the Earth stopped spinning, 85% of the world's population would experience supersonic winds

The planet's equator moves about 470 meters per second—over 1,000 miles per hour—and air there would continue moving at this speed for several minutes if the ground stopped rotating. These conditions would cause tsunamis, global storms, and fling debris fast enough to destroy nearly all human-made structures.