The Restless Earth Flashcards
What is the structure of the earth?
Inner core, outer core, mantle, crust
What is a plate?
A section of the earth’s crust
What is a plate margin?
The boundary where two plates meet
What is the mantle?
The dense, mostly solid layer between the outer core and the crust
What are convection currents?
The circular currents of heat in the mantle
Oceanic crust rock type
Basalt
Continental crust rock type
Granite
Oceanic crust location
Underneath the worlds oceans
Continental crust location
Underneath the continents
Which type of crust is older, oceanic or continental?
Continental (1500 million to 3.8 billion years old) Oceanic crust is 200 million years old
Which type of crust is more dense?
Oceanic (3g/cm3) Continental crust is 2.7g/cm3
Which type of crust is renewable?
Oceanic, continental isn’t
Which type of crust can be destroyed?
Oceanic, continental can’t
Which type of crust is deeper?
Continental (up to 70km) Oceanic is 6-10km
What minerals do the two crusts contain?
Oceanic- Silice and magnesium (sima)
Continental- Silice and aluminium (sial)
Similarities between the two crusts
Both crusts float on the mantle Both are made of rock Both contain silice Both formed from all 3 types of rock (igneous, sedimentary and metamorphic) Both brittle solids and fragment readily
Differences between the two crusts
Continental cannot sink
Continental cannot be renewed or destroyed
Continental is less dense than oceanic
Continental is older than oceanic
Oceanic can sink Oceanic can be renewed and destroyed Oceanic is more dense than continental Oceanic is newer than continental Oceanic is influenced by convection currents in the mantle, unlike continental
Constructive plate boundary
Two oceanic crusts moving away from each other, volano formed where these plates leave a gap
Destructive plate boundary
More dense oceanic crust slips under the less dense continental crust. Oceanic trenches are formed where the oceanic crust slips under. Earthquake activity can occur if plates stick. There can also be volcanic activity near fold mountains on the continental crust.
Example of a destructive plate boundary
West coast of South America