What evidence links the Chicxulub crater to the mass extinction?

There is a powerful, multi-layered body of evidence that conclusively links the Chicxulub crater to the K-Pg mass extinction (which killed the non-avian dinosaurs).

1. The "Smoking Gun" (Iridium Layer): This is the most crucial piece. In 1980, the Alvarez team discovered a global layer of clay rich in iridium, an element common in asteroids but rare on Earth. This layer precisely marks the Cretaceous-Paleogene (K-Pg) boundary, the exact geological moment the dinosaurs vanished from the fossil record. This suggested a massive asteroid impact.
2. Finding the Crater: Scientists then searched for a crater of the right size (over 100 km) and, most importantly, the right *age*. In the 1990s, the Chicxulub crater in the Yucatán Peninsula was confirmed. It is over 180 km (110 miles) wide and radiometric dating shows it formed **66 million years ago**, a perfect match with the iridium layer and the extinction.
3. Geological Evidence:
   • Shocked Quartz and Tektites: These impact-specific materials (melted rock and stressed quartz) are found in the K-Pg boundary layer all over the world, but they are thickest and largest near the Caribbean, pointing directly toward Chicxulub as the source.
   • Global Soot Layer: A layer of soot is also found at the K-Pg boundary, evidence of the widespread global wildfires ignited by the impact's thermal blast.