C2 Flashcards
(170 cards)
What is the crust?
The earths thin outer layer of solid rock
What is the average depth of the core?
20km
What is the lithosphere?
It includes the crust and the upper part of the mantle, it is made up of a jigsaw of ‘tectonic plates’
Give two properties of the lithosphere
It is relatively cold and rigid
It is over 100km thick in places
What is the mantle?
The solid section between the crust and the core
What happens as you get closer to the mantle?
The temperature increases
As the temperature increases what happens to the mantle?
It becomes less rigid
It can flow very slowly
It behaves like a semi-liquid
Give a property of the core
It is just over half the Earth’s radius
Give a property of the inner core
It is a solid
Give a property of the outer core
It is a liquid
What are convection currents?
The heat from the core rises up and causes the magma to go towards the crust, as the cool magma from higher up falls closer to the core. This causes currents in the magma to move the tectonic plates of the lithosphere to move.
Why do the tectonic plates float on the mantle?
Because they are less dense than the mantle
What happens to the continents when the plates move?
The continents move too
How much do the plates move each year?
2.5 cm
What happens when the plates meet?
Volcanoes and earthquakes
Why can’t you get to the inner structure of the earth directly?
Because the crust is too thick to drill through
What waves to scientists use to study the Earth’s structure?
Seismic waves (shock waves)
How can seismic waves be produced?
Earthquakes
Big man-made explosion at the earth’s surface
How can scientists draw conclusions about the structure of the earth?
By measuring the time that it takes for seismic waves to travel through the earth, and finding out where they are detected.
What are the two types of seismic waves?
S-waves
P-waves
What can P-waves travel through?
Solids and liquids
What can S-waves travel through?
Solids only
S-waves can travel through the mantle which means that it is _____.
Solid
S-waves are not detected in the core’s shadow, so the outer core must be _____.
Liquid