Chapter 4 Armando Peralta

Chapter 4 builds off of the concepts that chapter 2 and Chapter 3 discussed by describing a scientists attempt to prove the most popular extinction event: the death of dinosaurs via big rock from space or rather the effect said rock from space had on the planet. Scientist Walter and Luiz Alvarez are responsible for the theory that dinosaur were killed by an asteroid crashing on earth. They discovered large amounts of iridium in a crater in Italy called Gubbio. Iridium comes from asteroids and thus they theorized that an asteroid was responsible for everyone's least favorite extinction event.  Of course their theory wasn't immediately accepted and was met with opposition from uniformitarians that argued that extinction is a slow and gradual process,  what the Alvarez's argued fit more along the lines of catastrophism. Walter and Luiz didn't argue that the impact was responsible but the disturbance the impact had. The theme of science being a process again pops up as new information is presented but it must be evaluated before it becomes the new accepted norm.  I have one question regarding the theory of an asteroid impact which is how do scientist know that iridium comes from asteroids? Is there an somewhere on earth from which they were able to extract iridium off of?