About 13,000 years ago, life on Earth changed faster than what seems possible. Massive animals that had survived thousands of years suddenly disappeared from the landscape.
At nearly the same moment, the Clovis culture, known for its distinctive stone tools, faded from North America’s archaeological record.
For decades, scientists searched for a clear explanation, since slow climate change alone could not fully explain such rapid losses.
New research now strengthens an idea that once sounded extreme. A study published in PLOS One suggests that a fragmented comet exploded in Earth’s atmosphere, unleashing destruction across large regions.
The study was led by Professor James Kennett at the University of California, Santa Barbara, along with an international group of researchers. Instead of focusing on large craters, the team examined tiny mineral clues hidden in ancient sediment.
Signs of a comet explosion
The study proposes that a large comet broke apart as it entered Earth’s atmosphere. Rather than striking the surface, fragments detonated in midair, producing powerful shockwaves and extreme heat.
Scientists describe this kind of event as a low altitude airburst. Such explosions can cause massive damage while leaving no obvious crater behind.
The researchers studied three famous Clovis archaeological sites. These included Murray Springs in Arizona, Blackwater Draw in New Mexico, and Arlington Canyon on California’s Channel Islands.
Each site contains evidence from the exact period when Ice Age animals and Clovis tools disappeared.
“These three sites were classic sites in the discovery and the documentation of the megafaunal extinctions in North America and the disappearance of the Clovis culture,” said Kennett.
At all three locations, the team found shocked quartz, a rare form of sand grain altered by extreme heat and pressure.
Climate cooling after comet explosion
The timing of these discoveries aligns with the beginning of the Younger Dryas. This period brought a sudden return to cold conditions after Earth had already started warming following the last Ice Age.
Temperatures dropped quickly and remained low for roughly one thousand years, disrupting ecosystems across wide areas. Many ideas have attempted to explain this sudden cooling.
Kennett and colleagues support the Younger Dryas impact hypothesis. This theory suggests that comet explosions triggered massive fires and injected dust and soot into the atmosphere. “In other words, all hell broke loose,” Kennett said.
Dark smoke would have blocked sunlight, creating an impact winter. Rapid ice melting may have added fresh water to oceans, further disrupting climate systems.
Under such harsh conditions, large animals struggled to find food, while human communities faced extreme environmental stress.
Burned Earth and rare elements
One striking feature supporting this theory is a dark sediment layer called the black mat. This layer appears at many sites across North America and parts of Europe.
The black mat contains carbon rich material that points to widespread burning over vast landscapes.
Scientists also identified unusually high levels of rare elements such as platinum and iridium. These elements commonly appear in comets and asteroids.
Other impact-related materials include nanodiamonds, tiny metallic spheres, and meltglass formed when minerals melt and cool rapidly.
Each of these materials adds another layer of evidence pointing toward a catastrophic event from space.
Proof from the sand
Among all the clues, shocked quartz stands out as one of the strongest indicators of a cosmic impact.
These quartz grains contain microscopic fractures that form only under extreme pressure and temperature. Normal fires, lightning strikes, or volcanic eruptions cannot create this type of damage.
Using advanced tools like electron microscopy and cathodoluminescence, the researchers confirmed that the quartz grains from all three sites experienced conditions far beyond ordinary Earth processes. Some fractures even contain melted silica, proving exposure to intense heat.
This discovery also explains why no large crater exists. Airbursts release energy above the surface, destroying ecosystems without leaving long lasting scars in the ground.
“There are different levels of shocked quartz,” Kennett said. “There are going to be some very highly shocked grains and some that will be low-shocked. That’s what you would expect.”
Computer simulations using hydrocode modeling showed how low altitude explosions could create the exact shock patterns seen in the quartz.
A comet explosion that changed life
When shocked quartz appears alongside black mats, nanodiamonds, and impact spherules, the evidence becomes increasingly difficult to ignore.
Together, these clues point toward a powerful cosmic explosion that reshaped Earth’s environment in a very short time.
The study concludes that this event likely acted as a major contributing factor in the extinction of Ice Age megafauna and the collapse of the Clovis technocomplex at the onset of the Younger Dryas.
The study is published in the journal PLOS One.
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