The structure of the Earth Flashcards
inner core
- 1200km
- solid
outer core
- 2250 km
- liquid
Mantle - mesosphere
- 2900 km
asthenosphere
The asthenosphere is the highly viscous, mechanically weak and ductile region of the upper mantle of the Earth. It lies below the lithosphere, at depths between approximately 80 and 200 km below the surface.
lithosphere
- the crust and upper-most solid mantle
- 80-90 km thick
- divides into seven plates
- few smaller plates
what are the two types of plates?
- oceanic
- continental
- dependent on the type of material they are made of
continental crust - thickness
30-70 km
continental crust- age
over 1.5 million years
continental crust - density
2.6 (lighter)
continental crust - composition
- SIlicon
- ALuminium
(SIAL)
oceanic crust - thickness
6-10 km
oceanic crust - Age
less than 200 million years
oceanic crust - density
3.0 (heavier)
oceanic crust - Composition
- SIlica
- MAgnesium
(SILMA)
how many plates are there?
7
what are the 7 plates?
- Eurasian plate
- African plate
- America - south and north America
- pacific - middle of ring of fire
- Nazca - west of South American plate
- Antarctic plate
What is magma made up of?
molten rock and liquids from the mantle accumulating in vast chambers at great pressures deep within the lithosphere. On reaching the ground surface magma is known as lava.
Igneous rock
rock formed by molten magma, either underground (intrusive) or on the ground surface (extrusive).
intrusive
it forms coarse-grained igneous rocks such as granite and dolerite and forms as a result of magma cooling, crystalising and solidifying slowly below the surface which is intrusive.
- results in igneous rocks such as basalt being fine-grained with small crystals.
extrusive
- lava is in contact with air or sea
- it cools, crystalises, and solidifies quicker than magma underground.
on reaching the surface what is magma known as?
Lava
crust
0-100 km thick
