Mid-term Review

Mid-term Review - Geology 240Lxg Notes 28/08/2009 18:35:00...

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Unformatted text preview: Geology 240Lxg Notes 28/08/2009 18:35:00 ← LECTURE 1 - 1/15/08 ← Geology 240Lxg “Earthquakes (a.k.a. Geophysics)” ← Professor Sammis ← Syllabus on blackboard.usc.edu ← ← Where do EQ occur, and why? ← plate boundaries ← What is an EQ? ← faults, slips, epicenters, hypocenters etc. ← What are EQ waves? ← Using waves to locate EQs ← Using waves to measure earth structure ← Reflection and projection ← EQ forecasting and engineering ← Zoning ← Where to build structures etc. ← ← Sciences ← ← Pure Sciences ← Physics (motion, matter and response to forces, energy) ← Chemistry (nature of matter) ← Applied Sciences ← Biological Sciences ← Descriptive : Classification ← Biochemistry ← Biophysics (radiation, reaction of cellular structures) ← Earth Sciences ← Classification ← Geochemistry Geophysics History of Earth Sciences Geological time • Relative time vs. absolute time ← ← Age of Earth = 4.6 Billion Years…dated by meteorites ← Age of Universe = 13.6 Billion Years…dated by the rate at which the universe is expanding…by reversing time, you end up at the Big Bang (a.k.a. 13.6 BY) • Where EQ occur and why: o Occur in belts, plate boundaries o What is an EQ?—EQ waves, using waves to locate EQ and measure Earth’s structure—layered/cross mantel Reflection/refraction o EQ hazard mitigation “prediction” forecasting, why it is such a difficult issue to overcome EQ engineering, make buildings safer EQ zoning • Sciences: o Pure sciences o Physics—motion of matter in response to forces, energy o Chemistry: nature of matter • Applied Sciences o Biological sciences: descriptive: classification o Earth sciences: classification o Biochemistry: interaction with radiation o *Geophysics: EQ fall into this category • History: geological time: relative time vs. absolute time o If you look at a cross section of the earth, layers are visible to the eye, the layers at the bottom are the oldest, layers at the top are the youngest o Unstable isotopes o Half life decay is an exponential decay curve The constant rate is Independent of temperature or pressure described by half life • How to find the age of a rock since it cooled from the time it was melted o MassU over Mass Pb=time • Age of the Earth: 4.6 billion years (dating meteorites, stony meteorites) o Most meteorites are collected in Antarctica • Type II: carbonaceous chondrites • The entire solar system is the same age, created 4.6 billion years ago o The oldest rocks in ocean basins are .2 billion years old (200 MY) • 13.6 billion years ago—Big bang o The Universe is now expanding at a measureable rate, if you go back in time you get a big bang and it all comes together which was 13.6 billion years ago, we have no idea what happened previously ← Age of the earth=4.6 billion years • dated by meteorites ← Universe=13.6 billion • dated by expanding rate LECTURE 2 - 1/17/08 • Continents move about 1cm a year...
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This note was uploaded on 09/04/2009 for the course GEOL 240Lxg taught by Professor 12:30-01:50pm during the Fall '07 term at USC.

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Mid-term Review - Geology 240Lxg Notes 28/08/2009 18:35:00...

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