structure of the earth Flashcards
who was one of the first people to consider the structure of the earth
the Greek philosopher Plato over 2000 years ago
who proposed one of the first theories about earths structure in 1692
Edmond Halley
what was Edmond Halley’s theory
that the earth was made up of hollow spheres like Russian doll
what is the true shape of earth
a geoid - it bulges around the equator and is fat at the poles
what causes the earths shape to be a geoid rather than a perfect sphere
centrifugal force from the earths rotation
what is the outmost layer of the earth called
the crust
how thick is the earths crust
between 5-10km beneath oceans and up to 70km under continents
how does the thickness of the earths crust compare to an apple
it is as thin as an apples skin
what are the two types of crust
oceanic and continental
what is oceanic crust made of and what is it called
Basaltic rock known as sima (silica and aluminium)
what is continental crust made of and what is it called
granite rock known as sial (silica and aluminium)
what is the widest section of the earth
the mantle
how thick is the mantle
about 2900km
what percentage of the earths mass does the mantle make up
84%
what state is the mantle in
a semi-solid (molten) state due to heat and pressure
what process in the mantle causes the tectonic plates to move
convection currents
what generates convection currents in the mantle
heat from radioactive decay in the core
what happens where convection currents diverge near the earths crust
plates move apart
what happens when convection currents converge
plates move towards each other
what is the outer core composed of
mostly iron and nickel
is the outer core solid or liquid
it is a semi molten liquid layer
how thick is the outer core
about 2250km
what is the estimated temperature of the outer core
between 2700 and 4200 degree c
what is the inner core made of
a hot dense ball of mostly iron
what is the estimated temperature of the inner core
about 5430 degrees c
what is the radius of the inner core
about 1220km
what elements make up the inner core
mostly an iron-nickel alloy
