1.1 Earth's structure and tectonic activity
earth's formation and structure
continental drift theory
seafloor spreading
tectonic plates and plate boundaries
collisions + gravity caused space material to combine
as size increased, metal and rock liquefied due to pressure
lighter material cooled down and formed earth's crust
after the earth atmosphere formed, temperatures cooled down, oceans formed and the water cycle began
structure
crust, mantle, outer core, inner core
volcanoes, meteorites, seismic waves and magnetic field help us understand the earth's interior
alfred wegner introduced the continental drift theory
the shape of continents, landforms and rock, and fossils are all evidence of this theory
pangea was a supercontinent formed 270 ma and it split 200 ma. it wasnt the first super continent
change in magnetic alignment across seafloor shows that different parts were created at different times
powering plate movement: pressure and nuclear fission both create heat< convection currents< upward and outwards movement
we know where the boundaries are thanks to earthquake data
plate boundaries different types: convergent plate boundary, transform plate boundary, divergent plate boundary, convergent plate boundary, young divergent plate boundary
divergent plate boundary: usually in the ocean but some are on land. mid ocean ridges, new seafloor created, earthquakes
transform: in ocean or continent. land neither created or destroyed, it can slip up and down. earthquakes
convergent subduction: where the ocean meets continental crust. earthquakes, deep sea trenches, friction can create magma and volcanoes
convergent collisions: where two continental plates collide. mountains form, earthquakes, small amounts of subduction