The Cretaceous Tertiary Extinction, By Walter Alvarez

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Dalia Rodriguez Historical Geology 205 November 25, 2015 KT Extinction
The Cretaceous-Tertiary extinction, also known as the K-T extinction, was a global extinction event that struck the Yucatan Peninsula at the end of the end of the Mesozoic Era, 65 million years ago. Walter Alvarez first discovered a meteorite big enough to be called a small asteroid that hit the Earth, creating the Chicxulub crater. Once the asteroid struck the North American continent, there were igneous rocks underneath the crater that contained high levels of a rare siderophile element, iridium. This catrostopic event had a massive effect on the environment, as several mammals, birds, and plants became extinct. It also caused an impact winter that made it impossible for plants and plankton to photosynthesis, as 75% of inland animals and 90% of marine species were affected. Not only did it cause an impact winter, but the asteroid also caused volcanic eruptions, climate change and sea level rise. Geologists have also found rich dinosaur, plant and marine fossils to illustrate the K-T extinction. This event not only caused species to become extinct, but it also had an adaptive radiation, as other species were able to diversify.
The asteroid colliding with Earth left evidence in the planets core and mantle with iridium and shocked quartz. Iridium is present in extraterrestrial objects like asteroids and meteorites. The asteroid impact
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