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Earth has experienced some truly brutal events in its distant past, and only recently have scientists managed to gather enough evidence to offer us a rough outline of these apocalyptic moments. While the asteroid that ended the reign of the dinosaurs is well-known, it deserves mention here due to a newly uncovered twist.
The story of Earth’s tumultuous early days is still unfolding, and the insights provided by modern science are far more thrilling than any blockbuster movie.
10. Younger Dryas Impact / Lake Agassiz
Around 13,000 years ago, many of North America's iconic megafauna, including mastodons, saber-toothed cats, and giant sloths, vanished. This mass extinction is linked to a climatic event known as the Younger Dryas period.
The Younger Dryas took place at the close of the last ice age, a time when Earth was warming and glaciers were shrinking. However, for an unknown reason, the warming abruptly ceased, causing global temperatures to drop by as much as 24 degrees Celsius (43 °F) in just a few decades.
This dramatic cooling lasted for over a millennium, causing the extinction of numerous species. Geologists have referred to this event as 'geologically instantaneous' and described it as 'the most extreme manifestation of climate change in the geological record.'
For years, the cause of this mysterious event remained unclear, but scientists now propose an intriguing theory. As ice ages end and glaciers retreat, enormous meltwater lakes can form within the glaciers themselves.
One such immense lake was Lake Agassiz. Covering an area of approximately 945,000 square kilometers (365,000 mi), it was about five times the size of North Dakota. The ice dam that held back the lake eventually collapsed, releasing nearly 16,000 square kilometers (6,000 mi) of cold, fresh meltwater into the warmer ocean currents, which caused a dramatic drop in Earth’s temperature.
A prevailing theory suggests that an asteroid impact may have triggered this sudden cold spell. Harvard scientist Michail Petaev and his team claim that the evidence of this impact can be found in the unusually high levels of platinum and iridium—cosmic signatures of an iron meteorite—discovered in a Greenland ice core sample from this part of the Holocene Epoch. Further research has revealed nanodiamonds and impact-related carbon particles in the same sediment layer, lending additional support to the theory.
9. Gamma-Ray Burst Induced Mass Extinction
From our vantage point on Earth, the cosmos may seem like a tranquil and serene expanse of the night sky. However, it is also the stage for some of the universe's most intense and violent events.
Gamma-ray bursts (GRBs) are the result of supernova explosions in the deaths of massive stars, making them the most powerful explosions known to humanity. The scale of their violence is beyond human comprehension, as they can last anywhere from mere milliseconds to several minutes, emitting as much energy in that brief span as the Sun will in 10 billion years.
Researchers from the University of Kansas and NASA have employed atmospheric modeling to propose that such an explosion might have been responsible for the mass extinction during the Ordovician Period. This event occurred over 200 million years before the first dinosaurs appeared, at a time when there were no significant animals or plant life on land.
Scientists have determined that even a brief 10-second gamma-ray burst from 6,000 light-years away could destroy half of Earth's ozone layer, exposing all living organisms to harmful ultraviolet radiation from the Sun. This would lead to the near extinction of small life forms, like plankton, that are crucial to the food chain. Additionally, atmospheric chemical changes would result in global cooling, causing widespread disruption to ecosystems across the planet.
Brian Thomas, a PhD candidate at the University of Kansas at the time, suggested that up to 60 percent of marine invertebrates may have been wiped out by such an event. Creatures living near the surface would have been directly impacted by the lack of food and the exposure to intense ultraviolet radiation from the Sun, while deeper-water species might have survived longer, only to eventually face the same fate as the food chain collapsed.
A fascinating BBC documentary explores this topic in greater depth, and you can watch it here.
8. Lunar Cataclysm
Picture Earth being bombarded by enormous space rocks, some as large as Texas-sized boulders, over the course of millions of years. This actually happened in the planet's distant past. '[Around 3.9 billion years ago,] Earth would have been an unbearable place to be alive,' says Robert Duncan, a researcher at Oregon State University.
This event, known as the Late Heavy Bombardment, marks a period when Earth faced a series of catastrophic impacts, likely caused by disruptions in the asteroid belt between Earth and Mars. The evidence of these collisions on Earth has long been erased due to erosion and tectonic activity, which is why it wasn't until the Apollo Moon missions that lunar rocks uncovered the true extent of this violent period.
Using chemical 'fingerprinting' and radiometric dating on Moon rocks, scientists have discovered that both the Earth and the Moon were bombarded by meteors around the same time that life is believed to have first started emerging on Earth. This bombardment is thought to have persisted for roughly 100 million years.
There are several current theories explaining the disruption of the asteroid belt: one is the existence of a 'Planet V,' which may have formed in the region of smaller planets but was eventually swallowed by the Sun; another, the most widely accepted, involves the gravitational resonance between Jupiter and Saturn's orbits; and a third theory posits a possible collision between the hypothetical 10th and 11th planets in the outer solar system.
7. Storegga Slide
Imagine if the UK were once a peninsula connected to Europe rather than an island. What colossal and violent event would have transformed this landmass into the island nation we know today?
Now, picture a landslide the size of Scotland, submerged in the depths of a prehistoric ocean, surrounded by untold, ancient, and dangerous marine life. The resulting tsunami would be nothing short of catastrophic. It's a terrifying image to envision.
Around 8,000 years ago, this exact scenario unfolded off the coast of Scandinavia.
A massive prehistoric earthquake shifted up to 3,500 cubic kilometers (840 mi) of sediment—about 2,000 times the amount displaced during the Mount St. Helens eruption. The debris slid across the sloping ocean floor for roughly 800 kilometers (500 mi).
The tsunami that followed struck the shores of Norway with a towering wave, 11 meters (35 ft) high. In the Faroe Islands, the wave reached 9 meters (30 ft), and in the Shetlands, it soared to 27 meters (90 ft). The landlocked Norwegian Sea broke free, flooding the marshy tundra (known as 'Doggerland') and carving out what would later become the English Channel.
'Anyone standing on the mud flats at that time would have been torn apart. The speed of the water was just so immense,' explains geologist David Smith from Oxford University. 'The waves could have been as high as 10 meters (33 ft).''
The earthquake may have been triggered by the collapse of spongy methane hydrate deposits on the ocean floor, beneath layers of massive sediments that had accumulated over an extended period. The tsunami hit the English coast with such force that it surged 40 kilometers (25 mi) inland, completely altering the coastal landscape and wiping out any hunter-gatherer settlements in the area.
The dry, frigid tundra that once supported thousands of mammoth-hunting ancestors was entirely submerged. Surprisingly, this was not even the largest ancient slide! Most experts agree that the title of the largest goes to the next event on our list.
6. Markagunt Gravity Slide
Geologists David Hacker, Robert Biek, and Peter Rowley published a study on a prehistoric landslide that was once believed to be a series of smaller, separate slides. However, their research revealed it to be one colossal, singular landslide. When compared to other ancient landslides—many of which are already impressive in their own right—this one dwarfs them all.
Around 21 million years ago, a massive landslide took place between what is now Beaver, Utah, and Bryce Canyon National Park. Volcanic activity had deposited large amounts of rocky sediment over time, which rested precariously atop a weaker layer of clay-rich sediment. The swelling of magma into a dome-like structure exerted even more pressure on the unstable layer below, eventually causing it to collapse. A violent event, such as an earthquake or eruption, may have triggered the collapse.
Once the landslide material became loose, the enormous sheet of rock slid across the softer clay layer for miles, only stopping when the clay reached its limits. Afterward, the upper mass continued its journey even further. The entire slide spanned over 89 kilometers (55 mi) and covered approximately 3,400 square kilometers (1,300 mi).
The landslide was incredibly fast and brutal, completing its destructive path in just a few minutes. It overwhelmed anything in its way, consisting mostly of enormous blocks spanning several kilometers each. Even today, these blocks remain upright and mostly intact.
The extreme friction created by the slide caused the rock to melt into glass-like structures called pseudotachylytes. The discovery of these pseudotachylytes was the first major clue indicating the scale and power of this ancient landslide.
5. Gibraltar Breach
The majestic Rock of Gibraltar provides a breathtaking view. From its Andalusian summit in Europe, one can gaze across the Strait of Gibraltar to the African coastline and watch ships navigating through this crucial passage.
5.3 million years ago, during an ice age, a land bridge emerged between Europe and Africa as the sea level dropped. This bridge blocked the Atlantic Ocean from entering the Mediterranean basin, which had turned into a desert with salty lakes leftover from seawater evaporation 300,000 years earlier.
As the ice age ended and sea levels rose, the land bridge weakened, allowing the waters to breach. What began as a mere trickle over several thousand years slowly gained momentum, eventually becoming one of the largest waterfalls ever witnessed. The flow carved an increasingly deeper channel as it surged forward.
The volume of seawater flowing through this breach was likely around 1,000 times that of the Amazon River! What began as a small stream eventually turned into a roaring torrent, filling up 90 percent of the Mediterranean basin within a few months, although it could have taken up to two years, according to Daniel Garcia-Castellanos, a geophysicist from Barcelona.
Under these extreme circumstances, the Mediterranean Sea would have experienced a daily rise in water levels of up to 10 meters (33 feet). This dramatic event wiped out all plant and animal life in its path, ultimately shaping the Mediterranean Sea into its current form.
The cause of this event is believed to be the subsidence of tectonic plates, although more research is needed to reach definitive conclusions about the exact mechanisms behind it.
4. Black Sea Deluge (Noah’s Flood)
The theory explaining the origin of the famous 'flood myths' from ancient cultures was proposed by none other than Dr. Robert Ballard—the man who discovered the wreck of the Titanic.
In 1999, Ballard led a marine expedition that uncovered signs of human habitation and man-made structures beneath the Black Sea. The discovery of an ancient shoreline and the remains of freshwater mollusks revealed that the Black Sea was once a freshwater lake. This evidence points to a massive flood, with radiocarbon dating placing the event around 7,000 years ago.
The rise in sea levels was triggered by melting glaciers during a warm period at the end of one of the many ice ages. This increased water level posed a threat to the Bosporus Strait region, which may have once been a land bridge. Today, it serves as a narrow land connection in Asia Minor, opening into the Black Sea.
At some point, this land bridge was breached. The Mediterranean Sea began pouring in at an astonishing rate of about 42 cubic kilometers (10 miles) of water every day, potentially with the force of 200 Niagara Falls, according to marine geologists Bill Ryan and Walter Pitman of Columbia University.
This catastrophic event likely left the survivors in a state of fear, passing down tales of the flood through generations. These accounts may have influenced the well-known flood legends of Noah, Gilgamesh, and various ancient cultures.
3. Theia Impact
The most significant cosmic collision took place when a Mars-sized planet, known as Theia, collided with Earth during the chaotic period of planetary impacts early in the solar system's history. Earth was nearly destroyed, transforming into a spinning ball of molten rock. This catastrophic event ultimately led to the formation of the Earth as we know it and resulted in the creation of the Moon.
After the catastrophic collision, molten debris was flung into space and remained in orbit around the remnant of Earth. Over time, this debris began to come together, eventually forming the Moon that we see in the night sky.
The Apollo missions, followed by the study of the rocks brought back from the Moon, revealed an astonishing similarity in the composition of both Earth and Moon rocks. This discovery led scientists to conclude that the Earth and the Moon were once part of the same object, separated by a violent collision with a protoplanet in the early history of Earth.
Daniel Herwartz, an isotope geochemist at the University of Göttingen in Germany, found that the oxygen isotopes in the Moon rocks matched those of Earth rocks, further supporting the impact hypothesis. “This group of meteorites has a very, very similar isotopic composition to the Earth,” he explained.
Some scientists believe that Theia may not have been a planet as traditionally imagined, but rather an E-type asteroid.
2. Shiva Impact—A Double Dinosaur-Killing Impact!
A new hypothesis suggests that the extinction of the dinosaurs was caused not by a single asteroid impact, but by two.
The famous Chicxulub crater, located in the Yucatán Peninsula in Mexico, marks the spot where a massive asteroid struck Earth, triggering global climate changes and mass extinction. The asteroid, which impacted the Earth 65 million years ago during the Late Cretaceous period, was 10 kilometers (6 miles) wide and created a crater that spans approximately 180 kilometers (110 miles) in diameter.
Just 300,000 years later, while Earth was still recovering from the previous impact, another asteroid measuring 40 kilometers (25 miles) in width collided with the ocean off the western coast of India, creating a crater that stretches 480 kilometers (300 miles) wide.
Paleontologist Sankar Chatterjee remarked, “If we are correct, this is the largest crater known on Earth.” The impact site was named the Shiva crater, after the Hindu god of destruction. This event is thought to have contributed to the separation of the Seychelles islands from the Indian subcontinent.
Some scientists argue that the Earth's crust was vaporized at the impact point, triggering flood basalt volcanism in the Deccan Traps (similar to the Siberian Traps). This eruption released toxic gases and accelerated the volcanic activity that was already occurring in western India at the time.
The asteroid impact was so intense that it caused a significant distortion in the Earth's lithosphere mantle and fractured the Indian tectonic plate where it struck. The devastating combination of kinetic impact energy, the resulting massive tsunami, a flood of lava, and the release of harmful gases would have left no chance for any species already struggling to survive.
This impact dwarfed the Chicxulub crater in both scale and intensity. As paleontologist Chatterjee put it, “The dinosaurs were really unlucky.”
1. 'The Great Dying'
Known also as the Permian-Triassic extinction event, “the Great Dying” stands as the largest mass extinction in Earth's history. This event occurred millions of years before dinosaurs ever roamed the planet.
Around 250 million years ago, at the close of the Permian period, 90 percent of life on Earth was obliterated. Only 4 percent of marine species managed to survive, and almost all of the trees vanished. The cause of this catastrophic event is believed to be the enormous 'flood basalt eruptions' that took place in what is now known as the Siberian Traps.
Flood basalt eruptions are different from typical volcanic eruptions. Rather than lava flowing from a cone-shaped mountain, it bursts out through large fissures in the Earth and spreads across vast areas. This kind of eruption is thought to have occurred when the Earth's landmass was unified as one supercontinent, Pangaea. The eruption’s epicenter was located in what is now Siberia.
The eruption spanned an astonishing 3 million cubic kilometers (720,000 mi) and lasted for millions of years. It released massive quantities of carbon dioxide and sulfur dioxide into the atmosphere, poisoning it and triggering rapid climate shifts.
An area as large as the United States was covered by lava to a depth of 1 kilometer (0.6 mi). The oceans became acidic and oxygen-starved, while oceanic circulation was disrupted. This was followed by short-term nuclear winters and long-term global warming. The devastation to life on Earth was immense, and it took millions of years for the planet to recover.
“It’s literally a singular event in Earth history—it’s a monster,” says MIT PhD Seth Burgess. “It makes Yellowstone (supervolcano) look like the head of a pin.”
