Ever changing earth Flashcards
(50 cards)
Inner core
-This is the densest part of the Earth
-it is solid because of the very high pressure
-its made out of iron and nickel
Molten iron outer core
-This is a dense liquid
-made of molten iron and nickel
-both of these metals are magnetic
- they make the earth behave like a giant magnet
mantle
-under the crust
-this layer goes down almost halfway to the centre of the earth
-most rock in it is solid , but just under the crust its almost molten
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crust
- it can be as thin as 5km under the oceans
- going up to about 70km under the continents
-its the least dense of earths layers - contains minerals
the atmosphere
- 80% of the air lies within 10km of the surface
what is the upper part of the mantle and crust called
lithosphere
convection currents
these occur in the mantle, acts like a conveyor belt for the plates.
plates move in different directions, this is determined by which way the convection currents are flowing.
hot liquid rock rises while cool liquid rock sinks back down
what are formed by divergent/ constructive plate boundary
new oceanic floor (igneous rock) are formed
transform/ conservative boundary effect
earthquakes
who invented the theory of plate tectonics
Alfred Wegner
what is the earth’s structure made up of
4 layers
- crust
- inner core
- outer core
- mantle
how many tectonic plates are there
7
what was Alfred Wegner
he was a German polar researcher, geophysicist and meteorologist
what was wegner’s earlier theory
that billions of years ago all the continents had been a single super continent called Pangea, his theory suggested that overtime the continents broke up and drifted apart
when was his pieces of evidence to back up his theory accepted
1960 years after he died
what were the pieces of evidence that backed up wegner’s theory
- matching fossils found on different continents separated by vast oceans
- the coastlines of some continents fit together like jigsaw
- similar rock formations on different continents
why did scientists not believe his theory
because earlier he couldnt explain how they moved
conservative boundary
plates move in opposite directions (side by side). they overcome friction and move suddenly. this is an earthquake
destructive boundary
plates move towards eachother. the denser plate sinks and melts. the less dense plates rises, forming mountaions
constructive boundary
as two plates move apart, magma rises into the gap. then the magma cool and solidifies to form new igneous rocks
tectonic plates
these plates are constantly moving due to convection currents in the mantle
1st step of the atmosphere
the earth was formed and had an atmosphere of hydrogen and helium gases
2nd step of the atmosphere
erupting volcanoes releases new gases into the air. the main gases were steam and carbon dioxide with some methane and ammonia being releases
3rd step of atmosphere
as the earth cooled down, the steam condensed and fell as rain. this is how the oceans were formed
