Unit 1A - Tectonic hazards Flashcards
What are the contents of the earth’s core?
a ball of solid and liquid (iron & nickel)
What are the contents of the earth’s mantle?
semi-molten rock that moves very slowly
What are the contents of the crust?
two crusts, continental and oceanic
What is the continental crust?
thicker (30km-50km) less dense
What is the oceanic crust?
is thinner (5-10km) and more dense
Why are the plates moving?
because of convection currents in the mantle underneath the crust
What is the oceanic crust?
thinner(5-10km) more dense
Why are the plates moving?
because of the convection currents in the mantle underneath the crust
What is it called when plates meet?
plate margins or plate boundaries
What is a destructive margin?
is where two plates are moving towards each other
Describe how destructive margins occur?
oceanic and continental plates meet, the most dense plate is forced down in the mantle and destroyed, creating volcanoes and oceanic trenches
What is a constructive margin?
where two plates are moving away from each other
Describe how constructive margins work?
magma rises from the mantle to fill the gap and cools, creating new crust
What is a conservative margin?
two plates are moving sideways past each other/ same direction but at different speeds
Why do oceanic plates go under continental plates?
because it’s more dense
How are volcanoes formed?
- oceanic plate moves down into mantle, melted and destroyed
- a pool of magma forms
- magma rises through cracks in the crust called vents
- magma erupts onto the surface forming a volcano
What happens constructive margins in the formation of volcanoes?
magma rises up into the gap created by the plates moving apart