Astro2110 – The Solar System

The Chicxulub Impact happened approximately 66 million years ago, defining the end of the Cretaceous Period and the beginning of the Paleocene, as well as the end of the Mesozoic Era and the beginning of the Cenozoic Era. This impact not only managed to eradicate the dinosaurs as the dominant lifeform on the planet but also managed to kill off 50 percent of all biodiversity.

This impact was caused by an asteroid that was approximately 10 kilometers wide and hit the Earth at 30 kilometers per second, producing 3*10^23 joules of force. The impact was so large that it kicked up debris across the entire world, producing ash clouds that blocked the sun for years before the emissions of CO2 put the world into a massive temperature spike.

It is theorized that this asteroid originated from the from the asteroid belt, although from where is up to debate. Some suggested but discredited theories on where it originated from were from the Baptistina group of asteroids in the asteroid belt or from the remnants of a comet. The most modern theory of the asteroid originating from the main asteroid belt was determined from simulations, probability, and high deposits of chromium and platinum isotopes at the impact crater.

The idea that the dinosaurs went extinct by an asteroid hitting them is a relatively new idea. In Disney’s Fantasia, it shows the dinosaurs dying off by heat wave, exhaustion, and climate change. This was the common theory until this impact crater was discovered. Initially found by Walter Alverez and his father Luis Walter Alverez, the high levels of iridium in the clay in the late 1970s. An oiling company hired Glen Penfield and Antonio Carmago as geologists to scout the area, where they noticed the ridge present near the town of Chicxulub extended into the ocean creating a circle. Further research in the area revealed pink granite and other igneous rock that only form deep inside the Earth, brought up to the surface.

Despite being the most recent mass extinction event, as well as being one of the most sudden and impactful (literally), the Earth’s natural forces of erosion, plant growth, and oceans had covered up one of the larger craters on its surface. There was even a town in the center of the crater without anyone realizing it. It was so well hidden that it took until 1991 for a paper to be published declaring it to be an impact crater. Unlike other planets like Mars and Mercury, Earth’s changing atmosphere and lifeforms can erode and erase crater impacts with little evidence left.