Enviro sciecne Flashcards
what is the thinnest layer of the earth
crust 50km
whats under the crust
the mantle 2900km
what are crust and mantle made of
mostly rock
outer core material
liquid molten, 2300km
inner core
hottest layer of earth (6000 degrees C)
solid metals, 1200km rthick
what happens when we go below into the earth
temp and pressure both increase
who created the continental drift theory and when
Alfred Wegener, 1912
What is the continental drift theory
All countries and continents were 1 supercontinent 280 million yrs ago, called Pangea, but they drifted away due to earthquakes.
2 subcontinents of Pangea
Laurasia & Gondawa
Evidence for continental drift theory
Fossils found on the shore of numerous continents
fit together like a puzzle piece
mountain ranges connected
Convection
WW2 they discovered convection currents and earthquakes caused drift
What are plate tectonics
litosphere (crust) broken into slabs
What are plate boundaries?
perimeter of plate tectonics
oceanic crust
thinner and denser than continental crust
subduction occurs at most convergent boundaries
when oceanic crust sinks beneath continental crust plate, causing oceanic trenches and earthquakes.
when do earthquakes occur
when theres a lot of tension and tectonic plates get jammed and stuck, this caused sudden release in enerjy and the plates jolt, shaking the whole tectonic plate.
