Earth’s Structure

Question 1

describe the oceanic lithosphere

Answer 1

it’s under the oceans, made mostly of silica and magnesium rich igneous basalt, it is 5-10km thick, average density 3.0g/cm3

Question 2

describe the continental lithosphere

Answer 2

it’s the land masses, made mostly of silica and aluminium rich granite, up to 100km thick, average density 2.7g/cm3

Question 3

describe the mantle

Answer 3

widest section inside the earth, 2900km thick, mainly silicate rocks, increases in temperature and density as it becomes deeper, temperatures up to 3000c, average density even 3.4-5.6g/cm3

Question 4

describe the outer core

Answer 4

2200 liquid layer, mainly made up of nickel and iron, temperatures up to 5000 degrees, average density is 11.5g/cm3

Question 5

what is magma?

Answer 5

molten rock, gases and liquids from the mantle, when it erupts it is called lava

Question 6

what are igneous rocks?

Answer 6

they are formed by the cooling of molten magma, either underground (intrusive) or overground (extrusive)

Question 7

what is intrusive magma?

Answer 7

magma that cools, crystallises and solidifies below the earth’s surface

Question 8

what is extrusive magma?

Answer 8

magma that cools in contact with the sea or the air