GEOL 107 Notes - Teacher: Sara Feakins PDF

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Teacher: Sara Feakins...

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8/20/18 Class 1: Introductory ●

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What is oceanography? ○ The scientific study of the Earth’s oceans with the goal of understanding its processes and phenomena Where does the water in our ocean come from? ○ Origin of our solar system ■ Solar nebula condenses from past exploded star ■ Hydrogen is concentrated at the center and condenses enough to form our sun ■ Solar nebula rotates as it condenses ■ Protoplanets in eddies, then planets ○ Formation of the planets ■ Planets grew by accretion or condensation out of the “solar nebula” ■ Solar nebula = a cloud of dust left over after the formation of the sun ○ Age of our solar system ■ Meteorites date to 4.567 Ga ● Leftover bits from the time of solar system formation ○ Early days of planet earth ■ Collision (and other energy) generated heat ● Earth was molten (>1000 degrees C) ● Heavier molten iron sank to become the core, lighter material rose to the surface ● The lightest materials became the crust as a sort of “scum” on the surface ● “Differentiation of Earth’s interior”: Solid iron inner core, liquid iron outer core, mantle and finally crust ○ Structure of the Earth: Chemical ■ Continental crust (>30 km thick 2.67 g/cm cubed) ■ Oceanic crust (~5 km thick, >3.0 g/cm cubed) ○ Structure of the Earth: Strength ■ Lithosphere: “strong” ■ Asthenosphere: “weak” ○ Formation of the Moon ■ Glancing blow by a Mars-sized object ~4.5 Ga ● Re-melted some of both bodies ■ Involved primarily the mantles (not the cores) of each body ● Moon rock chemistry points to this ● We know the earth had differentiated by this time ■ Imparted more spin and tilt to the earth than would otherwise be expected ○ Stable liquid water ■ Eventually, earth cooled enough to support liquid water ● Mineral evidence suggests by ~4.1 to 4.3 Ga ● Ga = billion of years or 000, 000, 000 years

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■ Water allows oceans to form ■ Water allows life to begin Origin of the Ocean 1: Volcanoes ○ Volcanic H20 vapor outgassing from the earth as it cools ○ Current colanos emit: ■ H20 (water), 50-60% ■ CO2 (carbon dioxide) 24% ■ SO2 (sulfur dioxide) 13% ■ “other “ 3% Origin of the Ocean 2: Comets ○ Comets ■ Ice and rock Earth: Goldilocks Zone ○ Far enough from sun for H20 to condense into water ○ Close enough to sun for H20 not to freeze (most of the time) Venus ○ Closer to the sun ■ Water vapor does not condense ■ No oceans or rainfall ● CO2 does not dissolve ○ Runaway greenhouse effect Mars ○ Further from the sun ■ Colder ○ Smaller than earth ■ Most of the atmosphere escaped to space What is science? ○ A collection of facts that describe the world around us ○ OR ○ Discovering facts and underlying principles that explain the world around us The scientific method ○ We create hypotheses, and test them ○ Eventually some hypotheses survive falsification and they become accepted as part of scientific knowledge How does science work? ○ Science is a process ○ Observations (data) How much of the planet’s surface is covered by oceans? ○ The oceans cover 71% of the earth’s surface (they also contain 97% of planet’s water) How “good” is our data? ○ Observations are potentially biased ■ A sample may not be representative of population ■ Important concepts precision and accuracy

8/22/18 Class 2: History of Oceanography ●

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Polynesians - first ocean voyagers ○ From asia ■ To papua new guinea by 60,000 years ago ■ To polynesia 4000 BC - 1000 AD ○ More recently.. ■ To Hawaii ~450 AD and other remote islands ○ How do we know? ■ Archaeological evidence ■ Isotopic dating techniques The Mediterranean ○ Egyptian and mesopotamian cultures and early trade ~3000 BC ○ Greek colonization ~1000 BC ○ How do we know? ■ Archaeological evidence ■ Isotopic dating techniques ■ Recorded evidence ■ Funerary Boat ● Old kingdom, Dynasty IV; ~2600 BC Early egyptian and greek developments in our understanding of the oceans ○ Aristotle catalogued marine organisms (~350 BC) ○ Eratosthenes (a greek working at the library in Alexandria) calculated the circumference of spherical Earth (~250 BC) ○ Ptolemy (an egyptian-greek) oriented charts place N at the top, and dividing degrees into minutes and seconds (AD 90-168) Technological aids to sea voyages ○ Maps, later atlases ○ Coaster markers / lighthouses ■ Lighthouse of alexandria ○ Star patterns European exploration ○ 1480 to 1520 ■ Europeans rediscovered the Americas and sailed the pacific, indian, and southern oceans ○ Magellan’s boat 1520 ■ “Roomier” ships for long-duration cruises Scientific knowledge of the Oceans ○ 1768-79: Captain James Cook made three voyages of scientific discovery (HMS Resolution) ■ Cook prevented scurvy with sauerkraut!

Outline of Pacific Ocean, New Zealand, Australia, Hawaii Measured surface ocean conditions Sextant to determine latitude First accurate maps of oceans using a chronometer   (to determine longitude Harrison’s invention) Franklin-Floger Map (~1790) ○ Matthew Maury first recorded wind and currents Scientific knowledge of the oceans ○ 1831/36 (do not need to memorize) - HMS Beagle and Charles Darwin ○ 1872/76 - The HMS Challenger expedition ■ First modern deep-ocean scientific expedition ■ Deep ocean chemistry, temperature, biology, bottom sediment ■ Deep ocean sounding ○ 1925, German Meteor Expedition ■ First mapped areas of ocean floor using echo sounding ○ Post WWII ■ Global maps of ocean floor ■ Military interest in scientific research Recap on Ocean History ○ First seafarers in South Pacific ○ Egyptians and ocean science ○ European exploration ○ Tools aiding ocean voyages and science Knowledge ○ What you accept sufficiently “real” to allow you to take action upon and thereby live your life ■ Beliefs or feelings (individual) ■ Scientific knowledge (universal) Research knowledge ○ A way of gathering of knowledge that is not individual, but universal What is peer-review? ○ Scientific studies in academic journals go through peer review ■ All before publication ■ No profit motive ○ Compare to industry reports ■ ■ ■ ■

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8/27/18 Class 3: Plate Tectonics 1 ●

1500s on ○ S. Am and Africa seemed to fit together ○ 1596

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1620 ■ Sir francis Bacon - noted similarities in shapes of continents 1850s to 1940s ○ Distribution of fossils ○ Glacial evidence ○ New theory: Continental Drift Fossil distribution ○ Glossopteris flora ○ Mesosaurus ■ Freshwater reptile ■ S Am, Af. ○ Lystrosaurus ■ Land reptile ■ Af, Ind., Ant. 300 million year old glacial rocks ○ Glacial rocks distribution and ice flow directions ○ Scratch marks from glaciers in africa, etc. First theory - continental drift ○ Idea that continents move horizontally over Earth’s surface ■ Alfred Wegener (1910) ○ Major criticisms: no mechanism (how could continents move?) 1940 to 1970 ○ Seafloor topography ■ Bathymetry ○ Ocean crust vs continental crust ○ Paleomagnetism ○ Earthquake distribution ○ Volcano distribution ○ World war II prompted major advances in understanding the seafloor ■ SONAR - use sound waves to find depth to bottom ● Why? Submarine warfare, don’t want to crash! ■ Magnetometers - detect variations in magnetic field ● Why? Submarine warfare, aircraft or ship mounted to detect submarines Marie Tharp - first map of the seafloor ○ Famous for creating the first physiographic map of the ocean floor using bathymetry data collected along ship traverses around the ocean. Her work helped lay the foundation for the theory of plate tectonics ○ Depth measured from weighted rope or dynamite drops! Ocean bathymetry ○ Mid ocean ridges ■ Underwater mountain range, associated fracture zones ○

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Abraham Ortelius (Dutch Cartographer)- first to say continents joined together then separated

■ Varies but average depth is 2.5 km Trenches ■ Deepest parts of the ocean ■ Deepest is 11 km (Mariana trench) ○ Abyssal plains ■ Vast flat areas in between ridges and trenches ■ ~5.5 km Crust: two kinds ○ Continental crust ■ Felsic ■ 2.67 g/cm cubed ■ Less dense, rides higher, often thicker (30 km) ○ Oceanic crust ■ Mafic ■ 3.0 g/cm squared ■ Thin ( 20 m as wavelength decreases ○ Hilo, hawaii ■ 1946 - 150 people died ■ 1960 - 61 people died ■

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8/5/18 Class 5: Ocean Basins ● ●

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Unexplored frontiers? ○ Loss of Arctic sea ice changes geopolitics Newly navigable: Arctic Ocean ○ 2017 first tanker to cross Arctic without an ice-breaker ○ Reuters (august 2018) 12 days ago, first container ship with Russian fish and Korean electronics departed the Russian port of Vladivostok Future ship routes across the Arctic Ocean How is the seafloor mapped? ○ Echo sounding ■ Measuring ocean depth and revealing features on the sea floor, mapped much of the sea - Marie Tharp’s map ● Lacks detail as beam broadens with depth ■ Side-scan sonar maps a swatch in detail, but the ocean is vast Bathymetry of the Oceans ○ Abyssal Plains ■ >4 km deep ■ Relatively flat ○ Mid-ocean ridges ■ ~2 km deep ■ Long linear mountain chains ■ Fractures perpendicular to ridges ○ Continental shelves

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■ Shallow...