Geology 101, Week 2 Lecture Notes
Geology 101, Week 2 Lecture Notes GEO 101
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This 13 page Class Notes was uploaded by Jamie Bynum on Wednesday August 31, 2016. The Class Notes belongs to GEO 101 at University of Alabama - Tuscaloosa taught by Dr. Keene in Fall 2016. Since its upload, it has received 12 views. For similar materials see Dynamic Earth in Geology at University of Alabama - Tuscaloosa.
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Date Created: 08/31/16
Lecture: How Science Works August 23, 2016 Professor: Dr. Keene • Problems are not proof (Ex: Newton with falling apples and gravity) Prediction vs. Hypothesis Prediction: Black car will be hotter than white car Hypothesis: Dark colored objects absorb more solar heat than light colored objects *****Explanatory power is key! Hypothesis explains why, predic- tion doesn’t***** • If data is not systematically collected, it isn’t worth anything • Ask a speciﬁc question—collect speciﬁc data (evidence) Peer Review Example: 1. Write an article 2. Send to journal 3. Journal sends article to other scientists 4. Scientists critique article 5. Author gets critiques and revises article 6. Sends article back to journal 7. Article gets published ***All readers for own opinion*** 8. • Scientiﬁc theory is not a guess, hunch, or a random thought; has to be extremely well-tested; must be agreed upon - Newton’s Theory of Gravity - Germ Theory of Disease - Theory of Evolution by Natural Selection • Theories used to be laws; scientists realized their laws changed • Theories are never “proven” • Assumptions have to be relied on; not trivial - Biggest Assumption: Will things be the same tomorrow? • Uniformitarianism: Same action; different details Biggest Misconceptions: • Scientists are always changing their minds - Often due to news articles - Misunderstand scientiﬁc methods - Misunderstand research results • Conﬁrmation Bias • Anecdotal “evidence” • Common sense • Causation vs. correlation • A scientist is anyone who uses the scientiﬁc method almost every day • Scientists work in big universities, government, or industry Funding comes from: Industry University YOU (tax payer / consumer) Government Non-proﬁt organizations Lecture: Earth Structure/Plate Tectonics August 25, 2016 Professor: Dr. Keene Big Bang Theory: - 13.7 Ga - Formed Universe as we know it - NOT creation of all matter *******Ga = Billion years ago********* 3 Major pieces of evidence for Big Bang: 1. Expansion of the Universe - Einstein: Cosmological Constant (mathematical equation about the universe) - Edwin Hubble: All galaxies moving away from us (Universe is expanding) - High Frequency: Higher pitch (blue shift; moving towards) - Low Frequency: Lower pitch (red shift; moving away) 2. Abundance of light elements Early Universe VERY HOT (no atoms could form) - - Cooling brought formation of hydrogen and helium (simplest el- ements; only thing that could be formed at that time) - Built model-made prediction (24% of matter should be helium) [correct hypothesis] (George Gamow) 3. Cosmic Microwave Background Radiation - Heat left over from Big Bang - Predicted: 1948 - Found: 1965 by Penzias and Wilson TIMELINE • 13.7 Ga: Hydrogen and Helium (Big Bang) • 13.5 Ga: Nebulae form (Nebulae: Clouds of hydrogen and heli- um brought together by gravity) • 12.9 Ga: First Stars (closeness of nebulae) Enough time to make more complicated elements •4.57 Ga: Our solar system • 4.54 Ga: Earth formed (collided with meteorites and asteroids that cross its orbit until its orbit is clear) • 4.53 Ga: Moon formed (Earth hit planetesimal and blows back apart) • 4.5 Ga: Differentiation (elements of earth begin to segregate by density Earth’s Magnetic Field - Geographic north = magnetic south - Geographic south = magnetic north - Magnets wander and reverse - Magnetic ﬁeld protects us from Sun’s radiation Center of Earth is magnetic - What is earth made of? (Book ﬁgure 1.12) Atmosphere - Protected by magnetic ﬁeld - Denser towards surface - Combination of gases (78% nitrogen, 21% oxygen, 1% other) Layers of the Earth How do we know about the layers? Seismic geology uses natural or added wave energy; measure how the waves behave - The more powerful the energy source, the farther (deeper) waves will travel - Waves move different through different materials - Distance and time = velocity - Velocity helps determine the property of elements - Change in velocity determines boundaries Wave paths in the earth: • Waves normally don’t travel straight through Crust • Continental - 15-25 miles - Less dense • Oceanic - 4-6 miles - More dense Mantle - Soft solid (like play-doh) - Largest Layer - 3 parts: 1. Upper mantle (rigid) 2. Transition Zone 3. Lower mantle (malleable) - Convection (heat moving around) How do we know composition? - Seismic waves - Rocks through to have been formed there (strange rocks) More pressure and temperature with depth (acts more plastic) Core - Iron-rich - Outer: Liquid Creates dynamo that creates magnetic ﬁeld - Inner: Solid - Creates magnetic ﬁeld due to constant motion How do we know composition? - Seismic waves - Density (very dense and heavy) - Meteorite composition General Earth Properties: - Going deeper into the Earth = pressure and temperature rise - Temperature + pressure + rock type = physical properties - Core stays solid due to extremely intense pressure Heat - At 100 km, rock gets soft - Core may be 8492 degrees Fahrenheit Heat in core comes from: • 1. Formation 2. Friction 3. Radioactivity Boundaries - Moho border is where the crust ends and the mantle begins Layers of the Earth - Lithosphere is the crust and upper mantle (hard; made of rock) - Asthenosphere is the lower mantle (soft)
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