GEOL ALL SEMESTERS NOTES

GEOL ALL SEMESTERS NOTES - Geology 1001 Week 1 Beginning of...

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Geology 1001 Week 1 08/05/2007 21:49:00 Beginning of Notes UNIT 1 Jan 17, 2007 Ch. 1 physical geology- deals with processes at or beneath the earths surface.  Geologic Time : It’s immensity (Billions of years) is very hard to grasp. a.) second- hours: earthquake, volcano b.) Hundreds of years: erosion c.) Millions of years: evaluation d.) Tens of million-billion years: mountain range forming Universe is about 15 Billion years old Solar system 4.5 Billion years old (4,500,000,000). Sun with 9 planets FIG.9-3 a.) Terrestrial- small, rocky, dense-mercury. Venus, Earth, Mars. b.) Jovian- Large, Gassy, Light. Jupiter, Saturn, Uranus, Neptune. Solar system formed from relatively cold material Formed from Nebula of gas and dust that undergoes accretion Fig. 9-3 gravitational attraction Earth warms up very rapidly Due to: Acretion – Collision, aluminum heating, Compression – Inner layer heating, Decay of radioactive materials – Inside earth, continues today. Early Earth became(partially) molten. Caused in part by collision with Mars size body; created moon, then cooled down. Rocks are very poor heat conductors Once crust forms, inside still remains very hot- even today: 5,000 ° C. Earth may be uniform in composition (inside and outside) at first, but because of heating became differentiated- Layered Fig. 1-5 Once temperature is high enough, iron melts and falls to the center, causes release of energy and
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more heating – called the Iron Catastrophe This huge heating event causes “boiling off” of volatiles from inside. Water, other gases “belched” to the outside- “The Big Burp” forms early ocean and atmosphere Fig. 1-8 both are different from today. Look at layering in 2 different ways - distances measured from the surfaces of earth- radius= 6400 KM Based on Composition Fig.1-5 a.) Crust- solid rock ~40 km depth b.) Mantle- different type of solid rock~ 40-2900 km depth c.) Outer core- Liquid iron 2900-5100 km depth d.) Inner Core- Solid Iron 5100-6400 km depth Based on Mechanical Strength a.) Top Layer (0~100 km depth) Lithosphere : cool, strong, rocky (rigid). Rocks much below melting point. Contains crust and part of upper mantle. b.) Next Layer (~100-300 km depth) athenosphere : hot, weak (ductile), rocks close to their melting points. Consistency like tar (silly putty) c.) Mesosphere (~30-290km depth) hot, strong, rigid, rocks under very high pressure Chemical Composition Top layer (crust) Most accessible and studied Fig. 1-7 Two elements (Big 2) makeup 75% of total. In order : Oxygen (O), Silicon (Si) These two with six other elements (Big 8) make up 99% of crust Aluminum (Al), Iron (Fe), Magnesium (Mg), Calcium (Ca), Potassium (K), Sodium (Na)
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Contrast this w/ the composition of the whole earth . Most abundant in order: Iron, oxygen, silicon, magnesium. Most of the Iron in the core, most of Mg….
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This note was uploaded on 04/28/2008 for the course GEOL 1001 taught by Professor Baksi during the Spring '07 term at LSU.

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GEOL ALL SEMESTERS NOTES - Geology 1001 Week 1 Beginning of...

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