Chapter 4 Abudul Gaku

Chapter 4 begins with the introduction of the hill town of Gubbio. It is located a hundred miles north of Rome. Long before people settled, it lay at the bottom of a sea. The remains of of small marine creatures built up for millenniums until the the uplift that created the Apennines Mountains also raised the limestone. This made me think about how many structures have a history behind them and that what we see now was a completely different places millions of years ago. Geologist Walter Alvarez is then introduced who found traces of an asteroid that was decided to have hit earth and cause the mass extinction of the dinosaurs. When studying plate tectonics in Italy, Alvarez found layers of marine fossils, as well as thick layers of clay embedding the limestone. Alvarez's theory was initially rejected because scientists believed that extinction happened at a slow rate. However, evidence that supported his claim started to appear. Shocked quartz was found dating back to the Cretaceous period and a large crater in Mexico was found with layers of rock from the same period. "Shocked quartz was first noted at nuclear test sites and subsequently found in the immediate vicinity of impact craters.(80)" This made me ask: Does all shocked quartz mean that there was an impact with the asteroid? The theme of this chapter is that science is a process and its a method of learning more about the world. Through science, we have discovered that there was a huge event (the asteroid) that took place on Earth and that is the reason for the shocked quartz and the craters that were found.