Geo 100-800 Ch 1&2 Notes
Geo 100-800 Ch 1&2 Notes GEO 100
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This 7 page Class Notes was uploaded by samantha Flavell on Tuesday January 26, 2016. The Class Notes belongs to GEO 100 at State University of New York at Oswego taught by Rachel Lee (P) in Fall 2015. Since its upload, it has received 30 views. For similar materials see Physical Geology in Geology at State University of New York at Oswego.
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Date Created: 01/26/16
Geology 100 Geocentric v Heliocentric Model gt Geocentric First view of the universe Believed the earth was at the center and all other celestial objects revolved around it Heliocentric Modern view That the Sun is the center of our solar system and all the planets revolve around it Sun Accounts for 998 of the mass of the solar system Planets Is defined as an object that is spherical with a clear neighborhood of other objects and orbits a star How to Make a Solar System Dust and Gas is compressed A Shock wave disturbs it Gravity takes over compressions accelerates Mass is concentrated at the center of rotating disks presolar nebula The central part of nebula where most of the mass is heats up Intema1 pressure at center of nebula is great enough to initiate fusion Huge amount of energy is released The most important fusion reaction in stars is HydrogenHydrogenHelium 1H1H2He Galactic Catastrophism Estimates nebula formation and star birth lt1 million years Making Planets Nebula organized in rotating protoplanetary disk Gas in disk cools and elements condense dust Dust grains rapidly clump together by gravity into planetismals Clumps grow larger and larger As they grow in size collisions become destructive Estimated to take lt100 million years to make planets Discovered gt1800 extrasolar planets Expanding Universe Theory gt All matter and energy was packed into an infinitely small point gt 137 billion years l ago the point exploded big bang gt Universe has been expanding ever since Doppler Effect Light from different galaxies shifted towards longer wavelengths red shift relative to closer galaxies All galaxies show red shiftall galaxies are moving away from us Higher frequencywavelengths closer togetherblue light moving closer Lower frequencywavelengths farther apartred light moving farther away Waves Disturbances transmitting energy from one point to the next in a periodic fashion gt The distance between two waves is wavelength Frequency is the number of waves passing a point in a given interval Doppler effect was suggested by CJ Doppler gt The Doppler effect can only be noticed with light when the light is moving very fast Stars and Galaxies Stars Balls of gas in which fusion reactions of the nuclear variety have occurred which produce both light and heat light year is defined as the distance which light will travel in one earth year Terrestial inner Planets Broad in size Richer in elements like Iron Fe Silicon Se Oxygen 0 Aluminum Al Magnesium Mg The elements that make up rocks Mercury Venus Earth Mars Mercury Mostly iron too close to the sun Venus acidic atmosphere at high pressure Earth only one with decent atmosphere Nitrogen and Oxygen and water Mars thin atmosphere C02 but had abundant water at some point Outer planets are mostly of volatile elements condensed and have low densities Jupiter Saturn Uranus Neptune these planets are dominated by hydrogen helium and methane gases and ices Ice is a general term that is not only referring to frozen water but to the solid state of many materials which could be a gas under the surface conditions of Earth 410 times larger than Eath Differentiation Take something well mixed and make its components into ordered arrangement Refractory and Volatile Elements Differentiation occurred due to different freezing points of elements Elements with high freezingmelting points are refractory condensed from a gaseous state at a high temperature Elements with a low freezing pointare volatile and remain gases at low temperatures before solidifying gt Strong thermal gradient Much hotter closer to the sun than far away vacuum of space doesn t conduct heat well In early nebula objects closest to the sun were heated to point that there refractory elements were boiled off movement of mass away from sun results in chemical differentiation across disk The inner planets are more enriched in refractory elements and generally poor in volatiles Outer planets are very volatile rich and refractory poor Planetary Leftovers Inner planets began as mixed up masses of accreted dust Still a lot of leftovers oating the solar system Early planets also heated up due to decay of radioactive elements gravitational compression impact yields energy which heats material up Forces of Nature Unlike gravity magnetism is a force which can both attract and repel Gravity the attractive force between two masses Force push or pull mass is a quantity of matter Chemical Differentiation in Planets Dense refractory elements sink to planet centers less dense material left at exterior As a result all of the inner planets have generally similar internal structures which include Iron rich core Silicon oxygen and magnesium rich mantle With further differentiation Earth also developed a chemically distinct surface skin called the crust Internal Structure of the Earth s Core Iron Fe Nickel Ni and some Sulfur S Also relatively rich in metals like platinum Pt and gold Au gt Initially mostly liquid has crystalized over time Cores of other inner planes are essentially solid now SolidLiquid interaction may account for magnetic field Outer core2260Km Inner Core1220Km Mantle Structure gt95 Si 0 Mg Fe Minor amounts of Al and Ca Largest volume layer Solid Not molten but able to ow Largest area of Earth2850Km Crust Structure Thin and rigid layer of scum on Earth s surface Mainly Si 0 Al Significant amount of Fe Ca Na K Mg Where much of Earth s volatile elements are concentrated 560Km Early Solar System Timeline gt 457 Byr Solar system assembled 452 Accretion of Earth Complete gt 445 Earth is formed 444 age of oldest lunar rocks 44 Earth s crust is in place 42 Earth s hydrosphere is in place Earth needed to cool down for this to form 40 Meteorite bombardment in rapid decline 40 end of actiVity on Mercury 30 End of actiVity on the moon 13or later end of actiVity on mars lByr1000Myr 001 ByrlOMyr Meteorites Critical links to the Early Solar system and deep earth Every year 40000 tons of space dust and larger cosmic debris reaches Earth s surface Comets Chunks of ice and rock originating from outer solar system often accompanied by a coma and tail Asteroid Rock in orbit generally between mars and Jupiter Sometimes gets bounced towards Earth Meteoroid Space rock bigger than a dust grain but smaller than an asteroid If strikes Earth it is a meteoroid Meteor Streak of light seen When a space rock enters the atmosphere and starts burning up falling star Meteorite If a meteor doesn t entirely burn up a piece of rock that lands on Earth Meteorite 3 types 1 Stony I a Chondrite b Achondrites 2 Stony iron 3 iron Why Meteorites are important Give best estimates of age of the solar system Homogeneous meteorites called Chondrites give the best estimate of the bulk composition of the Earth Iron Meteorites match a lot of our remote estimates of the core Prior to mars pathfinder mission they give the best estimates of the composition and age of Mars Stonyiron meteorites may represent material from the coremantle interface Layer Composition studied meteorites as analogues for core and mantle Conducted laboratory experiments Density measurements of rocks from interior Characteristics of mantle derived rocks and minerals Determined high Pressure and temperature stability field of rocks and minerals Layered Earth Density is the key to understanding Earth s interior A plumb bob is de ected by a nearby mountain mass Density from this method 45 gcm3 is much higher than density of thin outer crust 25 gcm3 This suggests density most increases with depth Changes with Depth Pressure P Weight of overlying rock increases with depth Temperature T Heat is generated in Earth s interior T increases with depth Earthquakes Earthquakes seismic energy from fault motion Seismic waves provide insight into Earth s interior Seismic wave velocities change with density We can determine depth of seismic velocity change Hence we can tell where densities change in Earth s interior Seismic waves travel faster in areas with greater density
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