Space and Dinosaur Extinction

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3. a) What scientist first invented your theory and when? The Asteroid theory was formulated by Luis and Walter Alvarez in the late 1970s they were scientists from the University of California studying rocks in Gubbio, Italy. This theory states that a huge asteroid hurled itself on the surface of the earth triggering volcanoes and storms. The dust blocked the sun’s light for as long as years this killed many plants and without food the dinosaurs died too. b) Discuss the scientific evidence for your theory. When studying the rocks in Italy Walter and Luis Alvarez found very high concentrations of iridium in the rocks and these levels were close to the levels of the last dinosaur remains. The two natural sources of iridium are asteroids and lava from the Earth’s core. This led them to suggest that an asteroid collided with the Earth causing dinosaur extinction. More evidence to support this theory is that the layers of the rocks: the upper layer which contained soot which they believed came from global fires caused by the impact of the asteroid and the lower layer which contained quartz crystals and tektites which are found on asteroid impact sights. To add to this theory in 1990 a scientist Alan Hildebrand noticed a ring structure called CHICXULUB in Mexico which was a crater of 180kilometers in diameter and dated from around 65million years ago, the same time as the extinction of the dinosaurs. It was estimated that an object 10kilometers in diameter would have caused the crater and this fits in with Luis and Walter Alvarez’s calculation about the size of the asteroid that would have created the rock find. c) What evidence is there that discredits your theory? Palaeontologists have yet to find dinosaur fossils dating to the time off the impact. There have been a large number of asteroid impacts in the Earth’s history but none of these impacts have been the

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