Notes From Review Lecture.pdf

@j7zBBKXLJ9tyyqc76@2o2cKwE-b Marine Geology: Thing and rigid outer crust that floats on the higher dentistry mantle below ○ Oceanic crust Thin, dense, basalt Floats lower on mantle ○ Continental Crust Thick, granite, l...

@j7zBBKXLJ9tyyqc76@2o2cKwE-b Marine Geology: Thing and rigid outer crust that floats on the higher dentistry mantle below ○ Oceanic crust Thin, dense, basalt Floats lower on mantle ○ Continental Crust Thick, granite, less dense Plastic Upper Mantle: although solid, high temperatures cause the material to be dutile enough to flow on long timescales Molten outer core Solid inner core Paleobiogeography: Alfred Wegener lined up the minerals and fossils and said there must’ve been a supercontinent at some point ○ Proposed a wrong explanation and caused the issue to not be revisited for a while Mid-ocean ridges served as evidence ○ Magnetic anomalies *symmetric banding* showed that there were plate tectonics ○ Newest rock is along mid ocean ridges ○ Rock was being recycled at deep sea trenches Driven by convection of molten rock and slab pull (drag by gravity) Plate tectonics: Can have both types of crusts Continents move with the plates Divergent ○ Moving away Convergent ○ Moving towards Transform ○ Moving at an angle Geographic idea of where these collisions happen Mantle is fixed but plate slides over Sediment/creatures: Can go back in history to stud Shells of microscopic organism can infer species that are high/low productivity and warm/cold water Can grind shells up (can be o18 or o16 and it indicates the temperature) Isotopes and ratios give proxy temperature from years ago Mass extinctions: 5 mass extinctions have happened We are currently in our 6th 3 types of fossils: Body, trace, and chemical History of ocean: Mass extinctions every billion years (excluding asteroid) Conditions right for life: life First billion gives photosynthesis Another billion is multicellular life 550mn years ago is animal forms (cambrian explosion) Ithaca rocks are devonian rocks Cambrian Explosion: Snowball earth (what doesn’t kill you makes you stronger) Gene revolution Radiation of life Fauna: Evolutionary fauna Cambrian fauna Paleozoic fauna Current fauna Dominant forms of life Mesozoic marine revolution: Something changed in the ocean that created more primary production Allowed for big animals to live Strong predator pray Ocean waves: Waves can be constructive or destructive Two peaks gives bigger crests Trough and cro\est cancel Waves propagate energy not mass Wave Speed ○ Dep water is wavelength ○ Shallow is how shallow ○ Longer (faster), shallow (slower) ○ Dispersion Waves self sort out because of speed ○ Wave refraction  Shallow water Shallower = slowdown Creates complex coasts Winter vs summer ○ Summer pushes sand up on the beach ○ Winter aggressive waves store the sand on a bar Rip current ○ Swim across Wave height of wind generated function ○ Wind speed: sets upper possible limit of wave height ○ Duration: modulates upper possible limit ○ Fetch (distance which wind can blow without obstruction): modulates Tsunamis ○ Form when sea floor moves ○ Move at 550mph ○ Plates don’t slip in a clean way so they make an irregular wave that is hard to predict Tides: Equilibrium ○ Twice daily ○ Diurnal: one high tide and one low tide per day ○ Semidiurnal: two equal high and low tides per day ○ Mixed semidiurnal: two unequal high and low tides per day Dynamic ○ The idea that it is not just water basins on earth and continents play a role too ○ Tides slosh around because of the continents in a circular pattern+ Why? ○ Gravitational and centrifugal forces create two tidal bulges ○ Moon orbits the Earth at 28º ○ Figure: When the moon is at its 28º point, there is a high tide nearest to the moon (but on one, diurnal) The equator is semidiurnal On the backside it is mixed semidiurnal because of the degrees ○ Combined effect of the moon and the sun Magnitude on depending on whether the moon or sun pull together or pull against Look up and see a full moon, expect a large tidal range Spring tides: exaggerated Neap tides: attenuated tides - Right under the moon the centrifugal force and moon cancel each other out - Ocean tides are pinched up - Rotary tides  - Tides are like in a coffee cup being spun around - You end up with an amphidromic point with no tide, and as you move away the tides get larger and larger - Resonance: certain right frequencies like the bay of fundy can result in absurd ties Atmosphere: If you have a lot of water vapor than it weighs less (low sea level pressure) ○ Water molecule weighs less than nitrogen molecule Atmospheric convection: ○ Warm surface air is able to hold a lot of water vapor so it becomes moist ○ Moist surface air has low density so it rises and expands, it cools ○ Cooling causes precipitation ○ Condensation releases latent heat that drive the upward convection even higher You get the banding and the coriolis effects and you get the trade winds Temperature of the ocean: Thermocline: ○ Forms in the summer, get erased in the winter ○ Essentially a barrier between temperature as cold water is more dense Solar energy heats the ocean (add more than takeaway) Solar is much greater in the summer (inputs more than outputs) and vice versa in winter As you move from winter into summer, surface waters are going to get warmer, which blows up the beach balls (mixing depth gets shallower) (vice versa in winter) Ekman transport: All the wind can do when it blows on the ocean is move a slab of water to the right in the north and left in the southern Geostrophic currents: run along lines of constant pressure Subtropical Gyre: Trade winds push ekman layer into a center of high pressure Coriolis means that there is a gyre turning (to the right in the north) Spins around (wind piles up water) Equatorial Upwelling: Water is drawn up from the base to the shallow ekman depth ○ If thermocline is close to Ekman depth, cold water is drawn to surface (eastern pacific) ○ If thermocline is deep, only warm water is drawn to surface (western pacific) Water rises upward along the equator Equatorial divergence: splitting the ekman layer away with the wind You get a warm pool in western pacific Coastal upwelling:  Depends on the hemisphere Either the ekman layer is getting pushed into the coast causes it to downwell or be driven down Ekman layer getting pushed away from the coast calls it to upwell and cold water comes to replace it Know how to pick upwelling or downwelling Temperature-salinity signature: NADW: north atlantic deep water AABW: Antarctic bottom water AAIW: antarctic intermediate water A signature based on temperature and salinity It tells you where the water originated from and is going Speed of circulation of water: Cold tense water sinks in the north atlantic to form deep abyssal water North pacific salinity is too low to sink even though temperatures are just as cold as the north atlantic Deep water in the north atlantic moves south and merges with antarctic water Less c14 allows the sea to age Oldest deep water is in the deep pacific (2000 yrs) Coriolis force: In the north, coriolis is always right In the south coriolis is always to the left Conveyer belt circulation: Merging of the surface and deep circulation Heat is being pulled away from the equator, give the heat to the atmosphere at high latitudes Heat is pulled away, released at high latitudes, and then sinks and is recycled El Nino: Seasonal warming that originally occurred around christmas time Ever 3-7 years it had exceptional heating Southern oscillation: Sir Gilbert Walker analyzed atmospheric pressure data Sea level pressure ocillates between darwin and tahiti (when ones up, the others down) Walker Circulation: Winds at the ocean surface move away from the equator, they get turned by coriolis effect Winds aloft (above them) move in the opposite direction  The periodic reversal of the walker circulation cell Normal conditions: ○ Trade winds blow east to west ○ Modest tilt of thermocline ○ Convection and a lot of rain over western pacific and dryer conditions in the east ○ Upwelling and cooling in the eastern pacific El nino conditions: ○ All of that flips ○ Trade winds go opposite direction ○ Thermocline tilts down ○ A lot of rainfall on the west coast, indonesia has droughts ○ Little or no equatorial upwelling and strong warming in the eastern pacific La nina ○ Normal on steroid ○ Equatorial upwelling and cooling in eastern pacific ○ Really hard tilt of thermocline and really strong winds Global temperature anomalies: El nino puts a one year warming Creates a big bump in temperature that damages coral reefs El nino impacts: Direct: ○ A lot of rainfall off of california and south america, drought in indonesia ○ Thermocline goes deeper Sinks out of the reach of phytoplankton Productivity drops Indirect: ○ Distribus position of the jet stream