Geological processes Flashcards
Earth formation
4.6 billion years ago, proto earth with heavier elements sink to bottom (iron/nickel) and light elements in crust (silicon/oxygen)
structure of earth
solid inner, liquid outer, mesosphere, asthenosphere, lithosphere (rigid)
continental
less dense, granite
oceanic
more dense, basaltic
mantle
convection in upper mantle which breaks tectonic plates
how many plates
7 large, 8 small
hotspot
magma hotter than surrounding magma, use hotspots to see how continents moved
theory of continental drift
alfred wegner, said continents fit into a jigsaw and was one supercontinent
evidence of continental drift
fit of continents have similar rocks/geological sequences/fossils/climatic zones, paleomagnetism (measures how continents moved)
equation for continents moved
motion=distance/age
rate of tectonic movement per year
0.6cm-18cm
billion years
Gyr (duration), Ga (date)
million years
Myr (duration), Ma (date)
thousand years
kyr (duration), Ka (date)
years
yr (duration), date (a)
to work out duration
take away years before and after, make sure to convert units to make them the same
BLAG spreading rate theory
rate of tectonic movement, faster movement means more subduction/extension and more volcanism so more co2 and more climate change, slower movement means less
uplift weathering theory
when tectonics move crust up theres more weathering and makes silicates/hydrocarbonic acid which moves to ocean and forms calcium carbonic acid and removes co2 from atmosphere
thermohaline circulation
driven by density/temp/salinity differences, ocean cools becomes denser and sinks to bottom and travels to equator then heats up rises and travels to poles, strong in cretacous
gateway
antartica was connected to south america but disconnected when warm currents moved to south america and drake passge opened up with cold currents
