Why is iridium a good indicator of impacts by extraterrestrial bodies?
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Iridium is a metal in the platinum group of elements, which are very scarce in rocks of Earth's crust, because they are mostly dissolved in its molten iron core. These elements are always raining down on Earth as small particles of debris from asteroids or comets. The rate at which such debris hits Earth is known fairly accurately from measurements of the iridium abundance in cores drilled into the ocean floor.
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Body waves can be divided into two types: primary waves and secondary waves. What is the difference between these two types of body waves?
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What percentage of the people using coastal beaches in the United States developed ear infections, sore throats, eye irritations, respiratory disease, or gastrointestinal disease from swimming in seawater contaminated by infectious viruses and bacteria?
A. 1% B. 5% C. 25% D. 65% E. 90%
Which of the following gives the name for a weak trough of low pressure along which hurricanes occasionally form in the tropics?
A. permanent wave B. baroclinic wave C. easterly wave D. open wave
You are hiking on a mountain trail at sunrise when you smell the smoke from cooking bacon. You can't see where the smoke is coming from. Would you expect the camp to be above you or below you on the mountain? Explain
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