hazards stuff Flashcards
who proposed continental drift
wegener
what was Pangea
Pangea is what the world looked like before all the islands move apart.
what evidence is there to support continental drift
native fossils and plant species are found at the coasts of corresponding continents
looks like everything fits together
corresponding lithology in different areas
why do hotspots go against wegener
because the occur in the middle of the plate. This means that not all tectonic hazards happen at plate boundaries
divergent meaning
constructive boundary
convergent
destructive boundary
ocean ridges
the magma pushes up the ends of the plate boundary due to the pressure (mid Atlantic ridge)
what is the tall part of a rift valley called
the horst
what is the short part of a rift valley called
the graben
EARS ?
East African rift system
rift valleys
the asthenosphere is soft and malleable and the crust isn’t so when pulled apart the crust splinters and some pieces sink into the mantle(like if you pull apart a curly whirly) EARS
what boundary and plates are seen at an ocean ridge
constructive and 2 oceanic plates
what boundary and plates are seen at a rift valley
constructive and 2 continental plates
ocean trenches
when the oceanic plate subjects beneath the continental plate the continental may get wedged dragging is down causing a trench
what boundary and plates are seen at an ocean trench
destructive subduction and an oceanic and a continental
what is a hotspot
radioactive decay leads to energy being released creating super hot areas in the mantel. if a plate stays still for long enough it will burn through the crust creating volcanoes (New Zealand) not very common
where can you find fold Mountains
destructive subduction boundaries or collision boundaries (Himalayas)
why can fold mountains be found at subduction zones
because it the continental plate gets stuck it can buckle upwards causing a fold
how do island arcs form
the denser oceanic plate subducts into the mantle. this causes rapid melting of the rock and the new magma to rise and melt through the overlying plate.
what dictates the type of magma
the proportions of silica
what dictates the type of volcano
the type of lava