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TECTONICS CHP 1 - Coggle Diagram
TECTONICS CHP 1
plate tectonic theory
What is plate tectonic theory
Earth has 3 layers: crust, mantle, core
Core: innermost, 4400-600 degrees, 3300km
mantle: in between, 1000-3700 degrees, 2900km
crust: outermost, lowest, 6-70km
continental and oceanic plates
divergent and convergent and transform plate boundaries
heat from the core causes the semi-solid asthenosphere to melt
lithosphere divided into huge pieces called tectonic plates
convection currents -> tectonic plate movement
1.Heat from core causes mantle material to be less dense
2.Mantle material rises towards the surface
3.rising currents spread beneath the plates and drag them apart, causing divergent plate movement
4.mantle material loses heat and sinks towards the core
convergent plate movement occurs where the convection currents collide
materials get heated up again and the process repeats, rising and sinking of mantle material forms convection currents
slab-pull force -> tectonic plate movement
when two plates converge, the denser oceanic curst is pulled down by gravity as it subducts beneath the less dense crust
the denser oceanic crust sinks deeper into the mantle under its own weight, pulling the rest of the plate with it contributing to further convergence
seafloor spreading
evidence about seafloor spreading
Where two plates move away from each other at divergent plate boundary, seafloor spreading occurs
Magma from deep within the earth rises through the mid-ocean ridge
new oceanic curst is formed
how does evidence of seafloor spreading support the plate tectonic theory
Age of rocks nearer the centre (crest) of the mid-ocean ridge are youngest
shows how new oceanic crust is created at divergent plate boundaries and then moves laterally on both sides of the mid-ocean ridge as seafloor spreading occurs
little sediment accumulation is found at oceanic trenches as older oceanic crust is being destroyed at oceanic tranches
prove that new crust is continually formed as plates move
process when magma from deep within the earth rises through the mid-ocean ridges to form new oceanic crust
magnetic striping
what is magnetic striping
how does evidence of magnetic striping support plat tectonic theory
tectonic processes at different plate boundaries