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University of Toronto St. George
Earth Sciences
Bridget Bergquist

GLG205 January 17, 2013 Glacial interglacial cycles - Normal levels - Temp fluctuate 8 -10 degrees amplified when both poles have ice - Temp c02 correlated - Uncomforatbale periods for macroorgnisms glacial and inter glacial periods - Not suvive bc more succeptile to human climate change but numbers down bc of humans - Co2 at 290ppm - More gases planet will warm Global change Some basics 2 - Protons balanced by same number of electrons - Electrons bonding characterisitic The earth - One large mixture all three phases Radio - Some atoms formed during stars exploding unstable and those unstable they will give off energy or particle and converted - Alpha particle atom spits out helium - Gamma just energy Decay - Decay at predictive rate - Start with 100 percetn parent follows exponential curve daughter into goes up - Parent daughter ratio and know decay constant put date to something Time scale - Through dating radio decay and ustable isotopes dates put on figures Sequence of events - Two major ways of date things not always able to measure using geochronology - Not possible til instruments developed measure these things - Two ways date things - Sequence of events stratigraphy relative age dating - Lava flow is younger then the road - Looked at rocks Abs age - Put things in order - Law of superposition bottom older then top - Before 20 century and discovery of unstable isotopes radioactivey and mass spectromemter instrumebt measue at high enough precision Time scale - Used similar fossils in units to cross correlate layers over mass distances - Bony shells and well preserved before unicellular poor presentation and not much geo could do to differntaite or cross corealate - A lot of differentiation with bony sheeled organisms - Major shifts in organisms - Ass major changes in earths chemistry Aage of earth - Bible is 6000 years old - Hutton progression of rocks sedimentary rocks represent in and out of water deposit of shale and mudtsude ass with shallow seas and recceeed and come back - Past cycle of deposition and massice uplift of mountain ridges - Same processes today in past - Record very old In 19 century - Erosion rates the valley to form 300 million at least - All gravitational energy to smash planet how long to cool - Did not know other heat source 1896 - Istopes discovered - Idea dating and while for instrument to do dating in 1953 - Used lead isotopes - 4.55 age not improved on - Claire datinfg lead isotopes and next 30 years fighting oil industry get lead from oil and almost fired from university one man battle for 20 years Time scale - Ash layer – minerals good for age dating - Large ash layer deposited everywhere good mass correlation Basic geolog - Most intereersted in crust upper lithosp - Litho is 100 km of upper planet - Liquid outer solid inner Plaet tectonics - Two meet intense geo activity - Midocean ridges are Boundaries - Only planet in our solar system plate tectonics - Diffuse lines allow heat creep out of - Slow constant heat comes out and plates move around diverginent away - Midocean ridge is blue - Coming together converge uplift - and transform san andreas - 30 plates largest shown - Plate consists of crust and mantle thick layer of hot rock - Floats on aesthenosphere so hot float even though solid - Pangea masses in luarasi godwannaland 2 types - Cont less dense thick and older - Constantly formed at mid ocean ridge oceanic Plate tectonics - Drived from radioactive decay today - Convection currents - Spreading material from mantle forms new crust spreads away - Cean crust denser subduction some scrapped onto continentets Divergent - Close is younger cools and more desnse and sinks mountain range of sea higher colder denser and older and more flat Polarity - Shifts polarity in earth iron in rocks - Million years the polarity flips and measure it how plate tectonics was discovered - Move away age them and oldest oceanic crust 180 million old and japan Midocran ridge - A lot of heat come out - A lot of elements incompatrible for mantle organisms live high biodiversity and very toxic t human s - Cant keep these organism alive only observe in situ B con - Oeanic subduct lot of volcanism large trench - Volcanic island arcs smashed onto them and continents grow - Two oceanic colliding B - Massive upfliit when to continents collide - And massive thick crust C - Transform - Voocnaims ass not as dramtic as subduction - Stresses cause slide Hot spots - Is Hawaii - Hawaiian volcanic island chain - Hot spots with mantle through ocean or continental and Yellowstone is another midplate volcanism - Huge amount of volcanism - Hot spot still plate slide over - Oldest is 90 million years old - Islands stop building and erds - Go much longer but deeper and deeper as erode - Big island is moving off hotspot Volcanpnoes - Disasters bigger for human life - Magma rising at variety of spots comes to surface and create volcnoe Eq - Any shinting of lithosphere - Vibrations spread through walk - Happen anywhere deep down or shallow or deep along subdeucting plates Effects - Eq cause landslides and tsunamis - Giant see wave 2004 30 m high people live low coast more die Plate tectonics - New crust and subdection and plates sliding Rock cycle - 3 categories - Igneous the beginning of rock cycle – cool underground - Sed rocks through perceptiatiopn - Igneous and sedimentary buried and put under intense heat and pressure - Then metemprhic - And they erode to make sedimenrayr and some make it back to mantle complety remelted and part of rock cycle Minerals - Earths building blocks - Solid homogenous substance – characterize chemical compsiotn and reptive order of pattern - Participate a salt crystal is a mineral - Amorphous not crsytsal like obsidian – glass Rock - Usually a varity of minerals Minerals - Metallic like copper - And non metallic like silicate - Quartz all silicate - Phosphate non metallic - Mining people like sulfides and oxides rich metals and halides - Gypsum is drywall - And things occu alone Minerals - Ore operational definition high concentration we consider valubel - Non renerewable not replenishble on human scale
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