Plate tectonics and distribution Flashcards
what is the crust?
The outermost layer of the earth
What is the mantle?
A layer of rock between the core and crust made of molten rock.
What is magma?
liquid (molten) rock- the heat from the earths core has melted it.
What is the core?
Dense hot rock at the centre of the Earth.
What is a convection current?
As heat rises from the Earth’s core, it sets off convection currents in the mantle and this movement triggers volcanic eruptions and earthquakes.
What are the types of crust
Oceaic crust - this is found under the sea, thin but very dense
Continental crust - found under land, thicker but less dense
Conservative plate margin
Plate boundaries slide past each other which causes friction
Can be moving in the same direction or different
Triggers earthquakes
Destructive plate margin
Oceanic plate meets continental plate moving towards each other
Denser plate subducts into less dense plate
As it sinks it melts and makes magma called andesite
Oceanic plate sticks to the cont. plate and cause friction and pressure causing earthquakes.
Constructive plate margin
Two oceanic plates are moving apart from each other.
new oceanic crust is formed constantly in the gap created.
Magma is injected between two plates and cools down - shallow sided volcanoes
earthquakes formed by friction as the plates tear apart.
What is the global distribution of earthquakes and volcanic eruptions and their relationships to plate margins.
They happen on plate margins and tectonic plate boundaries e.g the ring of fire in Pacific ocean mostly on conservative plate margins.
What is the global distribution of volcanic eruptions and their relationships to plate margins.
Found on plate boundaries. Volcanoes from the constructive and destructive e/g Iceland has thousands of volcanoes in the Eurasian and African plates. Anomaly = hawaiin islands in the middle of the pacific ocean and not on plate boundary.
give an example of a plate boundaries
Nazca and south american -d
North American and Eurasian plate -con
North American and pacific -conser
