Summer 2025 : Plate Tectonics Revision Flashcards
What is the crust?
The solid, outermost layer of the earth. It is made of two main types (oceanic and continental) and broken into sections we call tectonic plates. 5-65km thick.
What is the mantle?
The layer of the earth directly beneath the crust. Made of molten and semi-molten rocks. 2900km thick. Convection currents occur here.
What is the outer core?
The layer of the earth between the mantle and the inner core. It is made of liquid iron and nickel and spins around the inner core. 2200km thick. Creates the earth’s magnetic field.
What is the inner core?
Solid ball of iron and nickel in the middle of the earth. 1250km thick. Around 5,500°C.
What is a tectonic plate?
A large slab of the earth’s crust.
What is a plate boundary?
The place where two plates meet.
What are convection currents?
Circular movements of material within the mantle. These help move the earth’s crust. Driven by heat from the core.
What is slab pull?
The pulling force caused by weight of a subducting plate. This drags the plate across the surface.
What is ridge push?
Plates slide away from the raised mid-ocean ridges. This drives the plate’s movement.
What is oceanic crust?
This crust that sits under the ocean. 5-10km thick. It can be destroyed at destructive boundaries and remade at constructive boundaries.
What is continental crust?
This crust sits under the continents. 20-65km thick. It is thicker but less dense and is never destroyed or remade.
What is basalt?
An extrusive igneous rock. Forms oceanic crust.
What is granite?
An intrusive igneous rock. Forms continental crust.
What does it mean to construct?
To build something.
What does it mean to destruct/destroy?
To destroy something.
What does collide mean?
When two objects (or plates) crash together.
What does diverge mean?
When two objects (or plates) move apart.
What is subduction?
When tectonic plates are forced downwards into the mantle.
What is magma?
Molten rock below the earth’s surface.
What is lava?
Molten rock above the earth’s surface.
What are fold mountains?
Created when layers of rock are bent and folded as two tectonic plates meet.
What is a mid-ocean ridge?
When two plates move away from each other, the edges are lifted, causing an underwater mountain range.
What is the Ring of Fire?
The name given to the edges of the pacific plate, where there are a very high number of volcanoes (and earthquakes).
What is an oceanic trench?
The deep seafloor valley created when two plates meet, and an oceanic plate is subducted (e.g. Mariana Trench).
