Rock Samples From Impact Crater Reveal Details of Dinosaur Extinction
About 65 million years ago, the dinosaurs and countless other creatures were going about their business on Earth when a space rock dropped out of the sky and brought about the end of the Cretaceous Period. But what was that fateful day like? We have a better idea today thanks to the International Ocean Discovery Program, which collected a pristine sample from the impact site.
The asteroid struck near the present-day Yucatan Peninsula, producing the Chixculub crater. Most of the crater sits under the Gulf of Mexico, so that’s where the researchers collected their samples more than 1,600 feet below the seafloor. The rock cores taken from the crater paint a bleak but fascinating picture of that day 65 million years ago.
The object was probably no more than a few miles wide, which isn’t much compared with a planet. However, its high relative velocity caused a devastating release of energy. At the time of the impact, the region was a shallow sea, probably no more than 100 feet deep. The impact produced a tsunami more than a thousand feet tall, and at the same time gouged a massive crater of melted, deformed rock known as shocked rock.
Based on the core samples (see below), the team estimates the impactor hit with the force of 10 billion Hiroshima atomic bombs. The blast ignited trees thousands of miles away, and the tsunami reached as far inland as present-day Illinois. The water flowed back into the crater several hours later, bringing with it soil and materials like charred trees picked up from the surrounding land.
The team was perhaps most interested by what wasn’t present in the samples: sulfur-rich rocks. The geological area around the crater has large deposits of sulfur, suggesting that the impact vaporized sulfur-bearing minerals and released the sulfur into the atmosphere. The team estimates that 325 billion metric tons of sulfur ended up in the atmosphere after the impact, which is orders of magnitude higher than what escaped during the 1883 Krakatoa volcanic eruption. That event lowered global temperatures by 2.2 degrees Fahrenheit.
The sudden high concentration of sulfur resulted in massive temperature drops across the globe, ensuring almost all dinosaurs perished. The only survivors among the dinosaurs were avian species, which eventually became modern-day birds. More research on the sample could reveal even more details about this tumultuous period in Earth’s history.
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