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Understand
Many meteorites like this one are made up almost exclusively of iron. What information can they give us about the Earth?
The iron found in meteorites is nothing like the iron found in the Earth. So this fact does not support the hypothesis that the nucleus of our planet is made of iron.
It does not provide us with any information about the Earth but it does provide us with information about the composition of the Solar System. So this fact does not support the hypothesis that the nucleus of our planet is made of iron.
We can deduce that the original materials that formed our planet were rich in iron too. So this fact supports the hypothesis that the nucleus of our planet is made of iron.
Analyse
Look at the graph and answer the questions.
What is the physical state of the Earth's interior from 2 900 km onwards?
It is liquid, as S waves only travel through solids and not liquids and there are no more S waves from that depth onwards.
It is solid, as P waves are able to travel from that depth onwards.
It is semi-solid, as both S and P waves can travel from that depth onwards.
Apply
If there was a big earthquake in Australia, what waves would be detected on a seismograph in Spain?
Both S and P waves, because even thought S waves cannot travel through the liquid core, they still reach Spain as they make the terrestrial particles move perpendicularly to them.
None of them, because the distance between Spain and Australia is so large that they do not reach Spain.
Only P waves, as the waves would have to travel through the core, which is in a liquid state, and they are the only ones that travel through liquids.
The mantle is made up of peritodite, a rock rich in iron and magnesium. Explain why the mantle is denser than the crust.
This is because the crust is made up of rocks rich in silicon and aluminium, which are not as dense asdenser than iron or magnesium. Additionally, the pressure in the mantle is higher, so it decreasesincreases its density even more.
Remember
Listen to the physical layers of the Earth being described and say if it is the lithosphere, asthenosphere, mesosphere or endosphere.
Lithosphere
Asthenosphere
Mesosphere
Endosphere
In both diagrams, the thickness of the crust and lithosphere are very exaggerated. Calculate the thickness of the continental crust (30 km) in a 20 cm diagram.
0.9 mm
9.55 cm
4.25 cm
Using isostasy, explain what is causing the lithospheric depression.
As the mountain range forms, its mass increasesdecreases. The decreasingincreasing weight of the mountain range makes the crust risesink, causing a lithospheric depression.
Explain, using isostasy, if the lithosphere would rise or fall in these situations:
Fall
Rise
a) Erosion of a mountain rage.
b) Deposit of sediment in a sedimentary basin.
c) Rising of a mountain range.
d) Formation of an ice cap.
Categorise the differences between the crust and the lithosphere.
Crust
Which is thicker, the continental or oceanic lithosphere?
The continental lithosphere is thicker, as the continental crust is also part of it and it is always thicker than the oceanic crust.
The oceanic lithosphere is thicker, as the oceanic crust is also part of it and it is thicker than the continental crust.
They have a similar thickness.
The thickness of the continental lithosphere must be around km and the oceanic lithosphere must be around km.
What does the sudden change in density at 2 900 km represent?
The boundary between the metallic outer core and inner core.
The Gutenberg discontinuity
The boundary between the rocky lower mantle and the metallic outer core.
Which areas are liquid and which are near to melting?
The upper mantleouter coreinner core is in a liquid state, given that the temperature is abovebelow the melting point. The upper mantleouter coreinner core is near to melting, as the temperature is below but near the melting point.
Explain how we discovered that the Earth has a liquid core below a depth of 2 900 km.
Explain, using isostasy, why it is so difficult to completely fill a river basin with sediment or erode a mountain range on the Earth.
you have completed the lesson!
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