EARTHSC 2GG3 Lecture Notes - Soot, Nitrogen Dioxide, Ordovician
8 Dec 2013
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Document Summary
The ultimate catastrophe: asteroid 10-15km in diameter struck yucatan peninsula of eastern mexico, Wildfires: darkness and abrupt cooling would last several years, from atmospheric dust, extinctions of plant and animal life, including dinosaurs. Space objects that cross earth"s path include: asteroids, comets, smaller pieces of rock that cause meteors. Identification of meteorites: types of meteorites are somewhat similar to rocks of earth"s deep interior. Evidence of past impacts: most impacts into oceans (2/3 of earth"s surface) are undetected or destroyed by subduction, continental impact sites are broadly distributed, but more have been found in populated or better exposed areas. Energy, mass and velocity ke = 0. 5mv2 ke = kinetic energy m = mass. Shatter cones and impact melt: energy output gives rocks distinctive features, such as shatter cones, glass spherules form from melted asteroid or target material. Impact melt may contain small but extraordinary amounts of nickel, iridium, platinum and other metals that are abundant in iron meteorites.
