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Topic 1 Restless Earth
Our earth is made up of 1. __ spheres known as the atmosphere,
hydrosphere, 2.__________ and geosphere with all 4 linked together.
To us the most important is the biosphere because that's where plants
and animals live, however the other spheres influence us too. The
geosphere can be divided into 3.__ major layers. Can you label them
The uppermost layer of the earth, the lithosphere is cool and brittle. It
contains the crust which is split into tectonic 4.______ which move
around slowly (about 2cms a year) on the semi molten upper mantle called the 5.
There are 2 types of crust, the 6. __________l crust which is low density, often made of granite
igneous rock and fairly thick (between 3050kms). There is also oceanic crust which is
7._______ (heavy), often made of basalt igneous rock and which is much thinner (only 68kms
thick). As you move deeper into the earth, the temperature rises. The mantle is solid while the
outer core is liquid. The 8.________ core is solid because it is under so much pressure from
above and composed of iron and nickel and is an amazing 50000C hot.
This heat inside the earth is called geothermal heat / energy. It is the result of radioactive rocks
such as uranium in the core decaying and releasing 9.______. As heat rises from the core it
creates currents of heat called 10.____________ currents in the outer
core and mantle. These are so strong that they move the tectonic plates
above them on the lithosphere.
Where convection currents rise and pull apart they rip plates apart creating
constructive plate margins. Where they rise and come together they cause
plates above them to collide forming destructive plate margins. Show this
on a little diagram here
If convection currents pull apart at the surface they rip the crust apart too.
This is called a 11._________ plate margin because new land is created
as magma from the mantle is extruded at the surface. Iceland's and its
many volcanoes and Mt. Kilimanjaro all formed this way. Draw a little
diagram here to show this plate margin
If 2 continental plates are forced to collide by convection currents below
them, both are forced up creating huge mountain ranges. This destructive
plate margin is known as a 12._______ zone. The 13. H________
Mountains were formed this way. Draw a little diagram to show this here
If one oceanic and one continental plate or two oceanic plates are forced
together by convection currents the lighter one will be subducted (forced
down) into the 13.________ where it will melt and return towards the
surface as magma (as is less dense than surrounding material) and may
even be erupted through a volcano as lava. This destructive plate margin
is known as a 14.________ zone. The Andes Mountain range in South
America was formed this way. Draw a little diagram to show this here.
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The final plate margin is known as a 15.___________ plate margin and
occurs where two tectonic plates are forced to slide past each other. The
San 16.__________ Fault in the USA is a great example of this. Draw
this margin here.
Friction at these plate margins triggers earthquakes while fractures in the crust allows magma
to reach the surface as lava and thus create volcanoes, but which of these do you find where.
1. At Collision zones, you get strong quakes but 17.…read more
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refugees (people forced to move). In the days after the eruption, an international relief effort was
mounted. The UN sent over 260 tonnes of food, governments around the world gave over
£35million in aid to the refugees and emergency vaccinations were given out.
34.__________ are another tectonic hazard. They kill many more
people than volcanoes as they are impossible to predict and often
affect a much larger area. They occur where rock breaks at a
tectonic margin and trigger seismic 35.______.…read more