reading3 - Clean Air Act of 1970 which banned the use of...

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Seema Ullal GE Cluster 70A  Dis 1A Reading Assignment 3 1. Radiocarbon dating can not be used to find the decay rate of an individual carbon atom. The formula for exponential decay can be used to give the half-life of the substance or the average-life of all the carbon atoms. Individual decay rates or life lengths cannot be found. Patterson perfected a method using lead and uranium isotopes to determine the age of the earth. After using ice-core testing in Greenland, Patterson realized that lead levels had begun to increase steadily (and dangerously) after tetra-ethyl lead was widely used in fuel. Despite strong opposition, Patterson kept campaigning against ethyl and helped introduce the
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Unformatted text preview: Clean Air Act of 1970 which banned the use of lead in gasoline. Lead will always be in the atmosphere but his efforts have greatly reduced its effects. 2. The KT boundary is a geological point referring to 65 million years ago when the dinosaurs and about half of the worlds other species of animals suddenly vanished from the fossil record. The iridium levels in the KT boundary were extremely high compared to normal iridium levels on earth. As iridium is abundant in most asteroids and comets, these high levels suggested that an asteroid struck the earth at the time of the K–T boundary. This theory had been proposed in the past but there was never compelling evidence....
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