Plate tectonics Flashcards Preview

Geography - Loraine > Plate tectonics > Flashcards

Flashcards in Plate tectonics Deck (16):

How thick is the crust?

Oceanic crust = 5km - 10km
Continental crust = 30km - 50km


How thick is the mantle?



Which sphere is deeper: asthenosphere or lithosphere?



How thick is the outer core?



How thick is the inner core?



What is a convection current?

Atoms breakdown and give off heat in the core, which causes the magma in the asthenosphere to rise towards the crust. However, as it ventures further away from core, it loses heat energy and cools down, making it sink back down. This is a convection current.


How do convection currents cause the tectonic plates to move?

The circular movement of the rising and falling of magma causes the plates to move.


What are the two different types of crust?

Oceanic crust and continental crust


Give 3 characteristics of continental crust

Can never be destroyed
Less dense, lighter


Give 3 characteristics of oceanic crust

Can be destroyed
Denser, sinks


Describe a divergent/constructive plate boundary

This is where the plates move apart from each other. This causes a shield volcano to be formed as well as new oceanic lithosphere to be created. This also forms a mid-ocean ridge, which is an underwater mountain range.


Describe convergent-destructive plate boundaries

This is where oceanic crust and continental crust meet and are pressed against each other. The oceanic crust gets pushed under the continental crust, creating a deep ocean trench and a composite volcano because the the sinking oceanic crust releases magma through the less dense continental crust. Earthquakes can occur here


Describe convergent-collision plate boundaries

This is where two continental crusts meet. Because they share the same density, neither sinks beneath the other so they both push up against each other and rise at the colliding point. This creates a fold mountain range, like the Himalayan mountain range. Earthquakes can occur here


Describe conservative/transformative boundaries

These boundaries are called this because lithosphere is neither created or destroyed. This is when the plates slide past each other. They can be sliding in different directions or sliding in the same direction, but at different speeds and get stuck in each other. The only natural disaster that can occur here are earthquakes.


Where do earthquakes and volcanoes typically happen? Do they always happen here?

Earthquakes and volcanoes typically happen around plate boundaries. However, they do not always happen here. An example of an exception is the Hawaiian Hotspot, which are a series of volcanoes. These volcanoes come from a plume from radioactive particles and are in the middle of the tectonic plate.


What is the subduction zone?

The subduction zone refers to when an oceanic plate piece sinks beneath a continental plate piece and into it's lithosphere. This occurs at a convergent/destructive plate boundary.