the structure of the earth

Question 1

the crust

Answer 1

the earth’s outer shell is the crust - his is the layer we live on. Yje crust varies n thickness frombetween 5-10km beneath the oceans to nearly 70km

There are to types of crust

• Oceanic- an occasionally broken layer of basaltic rocks known as sima (because they are made up of silica and magnesium)

conintela - bodies of mainly granitic rocks known as sial (because they made up of silica aluminium

sial is the upper layer of the earths crust and forms the continental land masses. Sima is the lower layer of the Earth’s crust and is found beneath the oceans as well as grading into the lower part of the sial beneath the continents.SIal is much thicker than oceanic sima,but it is less dense

Question 2

the litosphere

Answer 2

Together, the crust and the upper mantle are known as the lithosphere.It is in this zone that the tectonic plates formed

Question 3

The mantle

Answer 3

The mantle is the widest section of the Earth it is 2900km thick. The asthenosphere can move very slowly carrying the lithosphere on top. Due to great heat and pressure within this zone, the main silicate rocks are in a thick liquid state, which becomes denser with depth.

The rocks in the upper mantle are solid and sit on top of the asthenosphere, a layer of softer almost plastic-like rock.
The asthenosphere can move very slowly carrying the lithosphere on top. Densities within the mantle increase as you go down into the lower mantle

Question 4

The core

Answer 4

The core is the centre and the hottest part of the Earth- temperatures can reach 5000 degrees Celsius. It is mostly made up of iron and nickel and is four times as dense as the crust.

The core is actually made up of two parts. <the outer core is semi-liquid and is mainly iron, the inner core is solid and is made up of an iron-nickel alloy. It is not known for certain but is thought that as the earth rotates, the liquid outer core spins, which creates the earth’s magnetic field

The core’s internal heat is the major cause of the Earth’sactivity. Some part of this heat may be primeval - retained from the ball of dust and grass from which the Earth evolved.

Greatest source of heat energy within the Earth is derived directly from radioactivity.

The phenomenal heat at the core generates convection currents within the mantle above. These currents spread very slowly within the astheosphere