Deadly Rocks

(image from NASA)

            There are many theories on how the dinosaurs became extinct; one such theory involves an asteroid crashing onto Earth’s surface. “A large body, likely an asteroid from the belt between Mars and Jupiter was set into motion by a passing comet. This asteroid struck the planet on the Yucatan Peninsula in modern day Mexico sending millions of tons of dirt and water into the air,” (helium.com). “Upon striking, the comet would have sent dust and steam into the atmosphere and caused huge forest fires, tidal waves, severe storms, and eliminated all sunlight. It would be six months before sunlight would reach the ground after such a blow. The dinosaurs, even in their prime, stood no chance without sunlight and plant life,” (library.thinkquest.org).

(image of shocked quartz from australianmuseum.net)

 There is chemical evidence supporting this theory. “Tektites are quartz grains which are vaporized under intense heat and pressure, and cool into glass beads with no crystalline structure. Tektites were probably formed during a meteorite or comet collision,” (enchantedlearning.com). “When quartz is put under extremely high pressure, it can cleave in parallel planes. Shocked quartz is found at nuclear bomb sites and known meteorite impact areas,” (enchantedlearning.com) “Stishovite (Silicon Dioxide) is another form of quartz created under conditions of high heat and pressure. It is used as an indicator of meteor impact,” (enchantedlearning.com).

(image by John Sibbick)

           There are other theories that suggest possible ways the dinosaurs became extinct. The dinosaurs could have been killed by various volcano eruption, the eruptions would have sent huge clouds of dust, sulfuric acid, and poisonous gases into the air blocking the sunlight and changing the climate. Also the grounds would have been covered by molten lava. Climate change is another possibility, the temperature could have dropped, and since most of the plants at the time were tropical plants they would have died and messed up the food chain. Disease is the last theory; the dinosaurs could have caught a contagious deadly disease that killed them off.                                          
(image from Arenal.net)

Sources

http://www.helium.com/items/231759-how-the-dinosaurs-became-extinct

http://library.thinkquest.org/C005824/extinction.html

http://www.enchantedlearning.com/subjects/dinosaurs/extinction/Asteroid.html

http://www.johnsibbick.com/ (image)

http://www.windows.ucar.edu (image)
http://www.arenal.net/photo/latest/2007-september-mirador2-monteverde/ (image)
http://australianmuseum.net.au/image/Shocked-quartz  (image)