AST101H5 Lecture Notes - Continental Drift, Atomic Nucleus, Permafrost
Document Summary
7 - earth and terrestrial planets (oct. 26) Earth is being studied in tremendous detail = the science of geology. Earth"s general properties = our closest example of a major planet (some from. We will use earth to guide our investigation of other planets - particularly to other terrestrial planets. We use earth"s age to learn this. Chemical elements occur as different isotopes (from ch. The rate of change does not depend on the environment (temp, pressure, ), only on the properties of the atomic nucleus. Rate expressed as the half-life = time for 1/2 the isotopes to present to change. Carbon-14 nitrogen-14 with a half-life of 5730 years - this is very useful for archeology, but not for earth"s age. Potassium-40 argon-40 (a gas) with a half-life of 1. 25 billion years. For a rock measure the ratio of potassium-40/argon-40 = age of rock. Oldest rocks = 4. 5 billion years = age of earth.
