Chapter four - Waleska Reyes

Chapter four - Waleska Reyes

Kolbert starts this chapter by highlighting the city called Gubio, it is a hundred miles North of Rome. At the edge of the town there is the walls of gorge, which are also known as the Gola del Bottaione, it has bands of limestone on it. It is known that before people to the region of Gubbio was at the bottom of the sea. Remains of marine creatures built up year after year and eventually in the creation of the Apennine Mountains the limestone was elevated.

Kolbert then introduces a geologist named Walter Alvarez who in Gubbio discovered large traces of asteroids that were eventually identified as the ones who caused the mass extinction of dinosaurs. Alvarez also found marine fossils as well as thick layers of clay on those fossils after some tests he discovered that the clay had iridium. Signifying that asteroids with iridium were the ones who killed off all the dinosaurs. In the previous chapter the theory that mass extinction happens over time was presented. Alvarez’s findings contradict the theory of unifomatism. Later on new evidence began to be found regardaing Alvarez’s theory such as the discovery of shocked quartz, the discovery of sandstone, and a crater in Mexico.

At the end of the chapter Kolber concludes that the rules of survival are constantly changing. My question is how can a species evolve to fit every era the earth encounters? I connected this chapter with the theme that science is a method of learning more about the world. Alvarez’s study gave us new information about our planet that we were not exposed to before. Due to Alvarez’s research we were better able to understand how the earth became what it is today.