Origin Story: A Big History of Everything

by David Christian

When the asteroid hit, it was moving at thirty kilometers a second (about one hundred thousand kilometers an hour), having taken just seconds to fly through Earth’s atmosphere. We know exactly where it fell: in the Chicxulub (pronounced “Chikshulub”) crater in the Yucatán Peninsula of modern Mexico. The asteroid evaporated as it punched through the crust, leaving a crater almost two hundred kilometers across. Molten rocks were hurled into the air, where they formed dust clouds that blocked sunlight for many months. Limestone evaporated, spraying carbon dioxide into the atmosphere. An area hundreds of kilometers around the impact point was stripped of life. Hundreds of kilometers beyond that zone, forests lit up in massive firestorms. At sea, a tsunami formed a wall of water that crashed down on the shores of the Gulf of Mexico and killed fish and dinosaurs hundreds of kilometers away. In the Hell Creek Formation, in Montana and Wyoming, you can find fossils of fish whose gills are full of glass from the asteroid impact.