Chapter 4:

Kolbert describes a small town in Rome by the name of Gubbio. Gubbio is known for its limestone and in said limestone is where geologist Walter Alverez found proof of an asteroid hitting Earth causing the mass extinction of the dinosaurs. Alverez came from a family of scientists and was studying in Italy to study plate tectonics. Under the Earth’s surface he found many fossils but also a thick layer of clay. Alverez’s father, Luis Alverez, told him to study the clay for iridium. He found lots of iridium in the clay, signifying that an asteroid hit, he also found out that this asteroid hit during the Cretaceous period. They then wrote the “ Extraterrestrial Cause for the Cretaceous Tertiary Extinction”, documenting their findings. In the beginning, Walter and Luis Alverez’s idea of the asteroid causing the extinction of the dinosaurs was dismissed by fellow scientists. However, there was a lot of evidence backing them up. For example, they discovered “ shocked quartz”, quartz that was under a lot of pressure, and a layer of sandstone that was most likely caused by a tsunami during the cretaceous period. The biggest evidence was when scientists in Mexico found a huge crater that they nicknamed the “ Crater of Doom” that contained melted rock from the cretaceous period. This connects directly to the importance of evidence in science. Nothing is truly considered by anyone unless there is at least some evidence backing the theory up. William and Luis Alverez knew this and in turn provided the evidence needed to show the world what possibly could have caused the extinction of the dinosaurs and when they found the opportunity to prove their theory they took it, " Luis, according to a colleague, reacted to the news "like a shark smelling blood"; he sensed the opportunity for a great discovery" (pg 75). Science is about discovering new theories and providing evidence.