There are today about 200 known impact craters on Earth. Some of the craters are important to scientists in that they allow us to understand one of the most fundamental geological processes in the Solar System, other craters are also important because they teach us something about the life on our planet, for instance how fragile it can be. One of them is the Chicxulub impact crater at the Yucatán peninsula in México. The crater is buried below hundreds of meters of sediments that have accumulated through the millions of years that have passed since it was formed. Chicxulub is the only impact event so far known to have caused one of the five big mass-extinctions of life. The nearly continuous marine sedimentation of the Chicxulub area offers to scientists a kind of «history book» written by Earth itself. It begins by describing the world as it was before the impact event, a world often referred to as the «age of the dinosaurs». Then the next pages (i.e. the next layers) tell a tale of tremendous destruction. I have participated in this study in my function as a specialist on impact-related sedimentation in craters formed in marine environments. The Chicxulub sediments reveal tremendous transport energies that are much bigger than any other catastrophic flooding known on the planet. They also indicate an amount of sulfur released to the atmosphere sufficient to create a global, several years long, dark freeze house. All this and much more can be read from the sediments laid down during the first day of the Cenozoic, the first day of a new age dominated by mammals and eventually by our own species.