In scientific circles, the name of Chicxulub conjures up very different images. Scientists now agree that 65 million years ago, a meteor struck the planet at a point in or around the town of Chicxulub, forming an invisible crater. It was this meteor that they think was responsible for the extinction of the dinosaurs.
The following is taken from an article written by Susan Stewart, a resident of nearby Telchac Puerto.
Who would have thought that the small coastal town of Chicxulub would become world-known for a catastrophic event which occurred over 65 million years ago! Scientists had observed a thin layer of iridium – an element rare on Earth, but common in meteorites – all over the planet, and had theorized that a cataclysmic meteor strike had occurred at some point on the planet. But, if this was true, the impact crater would have to be visible. Researchers finally located the impact site on Mexico’s Yucatán Peninsula.
It is a huge buried impact crater that is called Chicxulub, a Maya word that roughly translates as “tail of the devil.” The crater, now buried beneath kilometer-thick sediment, has been imaged using new geophysical techniques. It appears to have a diameter of 145 to 180 km, which makes it one of the largest confirmed impact structures on Earth. The meteorite that produced the Chicxulub crater was about 10 km in diameter.
When an object that size hits Earth’s surface, it causes a tremendous shock wave and transfers energy and momentum to the ground. The impact was similar to a large explosion, although the energy of the Chicxulub impact dwarfs anything modern civilization has experienced. The energy of the impact was comparable to 100 million megatons of TNT, 6 million times more energetic than the 1980 Mount St. Helens volcanic eruption. The impact ejected rock from several kilometers beneath the surface of the Earth and carved out a bowl-shaped crater nearly 100 km in diameter. In addition, the shock of the impact produced magnitude-10 earthquakes, which were greater than the magnitude of any we have ever measured in modern times.
The impact crater also affected the circulation of groundwater on the Yucatán Peninsula. This groundwater, which dissolves the limestone of the Yucatán peninsula, has produced caves. At the surface, this has produced cenotes which are groundwater springs. The cenotes form a ring that coincides with the rim of the Chicxulub crater and is the only visible feature on the surface that indicates the huge crater below.
The Chicxulub impact event was an extraordinarily energetic event in Earth history. It also coincides with one of the largest mass extinction events in Earth’s history, which occurred 65 million years ago. Are the two events connected? That is, could an impact event have caused the deaths of so many plants and animals, and, if so, how? This is a subject of much conjecture amongst scientists.
We do know that to cause extinctions, extraordinary, long-term changes must have occurred in the Earth’s environment. In the vicinity of the impact, the blast and heat destroyed life. Forests were flattened to a distance of 500 to 1000 km. Because part of the crater was in a shallow sea, giant tsunamis radiated across the Gulf of Mexico. Dust particles ejected from the Chicxulub crater rose above the Earth’s atmosphere, covered the Earth, and rained back through the atmosphere around the entire world. The dust in the atmosphere blocked sunlight from reaching the surface around the entire globe.
Essentially, Earth experienced a nuclear winter, halting photosynthesis for up to one year, thereby disrupting marine and terrestrial food chains. While scientists are uncertain about actual events, they have evidence of massive forest fires. Charcoal and soot have been found in sediments around the world. These fires were probably started when the impact debris came raining back down through the atmosphere. This debris quickly heated the air, producing a temperature spike so high that vegetation spontaneously ignited.
Clearly, the Chicxulub impact caused severe environmental changes that could have led directly to the destruction of an entire species.
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