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Department of Paleobiology

A recently recovered deep-sea core contains convincing new evidence of an asteroid impact 65 million years ago, when dinosaurs went extinct. A section of the core is the centerpiece of a multimedia exhibit, "Blast from the Past," currently on display at the Smithsonian Institution's National Museum of Natural History.


The Asteroid Hypothesis

The conceptual sketch above depicts the asteroid moments before impact, as it takes aim on Mexico's Yucatan coastline. Approaching at an angle from the southeast, it will send the main force of its impact northward in a fire storm over North America. The evidence has grown so overwhelming that few scientists dispute that an asteroid nearly 10 km (6 mi) wide slammed into what is now Mexico's Yucatan Peninsula.


The impact blasted a 180 kilometer-wide (100 miles) crater many kilometers deep into the Earth.


The heat of impact sent a searing vapor cloud speeding northward which, within minutes, set the North American continent aflame. This fireball and the darkness that followed caused major plant extinctions in North America. Environmental consequences led to global extinction of many plants and animals, including the dinosaurs.


Lingering airborne debris is believed to have triggered darkness and a decline in the global temperature, making Earth uninhabitable not only for dinosaurs by also for many other plants and animals. Dinosaurs, like Triceratops depicted in this sketch, passed into extinction, ending more than 150 million years of evolution and dominance over life on Earth. Other organisms, including mammals like those shown in the lower left of this sketch, somehow survived. In the words of Dr. Brian Huber: "This event profoundly changed the course of life on Earth. If it had not happened, evolution would have followed a different path and in all likelihood we would not be here today."

Map of the Earth as it was 65 million years ago, when the impact occurred.

The drill ship JOIDES Resolution obtained the core 480 km (350 mi) east of Florida, more than 1,920 km (1,200 mi) from the now buried impact crater. The core was drilled 2,658 m (8,860 ft) below the ocean surface and 128 m (427 ft) below the ocean floor.

Dust and ash fallout as well as material blasted from the crater are clearly evident in the deep-sea core, which scientists recovered more than 1,920 km (1200 miles) from the impact site off the east coast of Florida.

Continued in Part 2...

Images by Mary Parrish, Map by My Le Ducharme.

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