The lithosphere includes the crust
and the upper part of the mantel.
The slow movement of tectonic plates is
caused by very powerful convection
It is cracked into a number of huge
pieces called tectonic plates!
These plates are moving
at a speed of 1cm each
The outer part of the
earth is called the
Mountains, alongside other of the
earths features, were thought to be
formed by hot, young earth cooling
at the crust started to shrink and
wrinkle, much like that of an apple
that is drying out and aging.
However there is now a new theory
of how mountains are formed.
The new theory is that mountains have been created by
rock that is being forced upwards due to the collision of
tectonic plates. This theory however has been introduced
quite recently and has only just been accepted.
Alfred Wegener had many ideas on continental drift;
his main evidence was that, like a jigsaw puzzle; the
continents two continents, South America and Africa
fitted together. As well as that they both have the
same patterns of rock layers.
Also the two coasts had the same type of plants
and animal fossils, some of the fossils found were
of animals that could only be found in these parts
of the world and they were proven to be unable
to swim or fly.
Finally there was not a
possibility for there to
have been a piece of land
connecting the two
continents therefore they
must have been joined
However this theory was too many peoples disbelief
as Wegener had no explanation as to how the
continents moved. Also although Wegener was a
scientist he was not known as a geologist but as a
meteorologist therefore his ideas were given less
credit by geologists.
As he was not a geologist his ideas were
not accepted until later in life, when
geologists did in fact discover that what
Wegener said was correct, this then helped
explain many other theories that have now
been proven. These theories are closely
linked to Wegener’s idea of continental
One of the ideas proven by continental drift is
that rock on the ocean floor is younger than
that on the continents as new rock has been
formed due to magma coming from inside the
earth causing the older rock to be pushed
Wegener’s idea was official accepted when there
was a discovery of underwater mountains and
volcanoes when the Atlantic Ocean floor was
THE ATMOSPHERE TODAY
The atmosphere is a
mixture of gasses that
surround the earth.
Nitrogen and Oxygen make up 99% of
the atmosphere. The other 1% are small
amount of other gases, mainly argon.
Water vapour is also
present in the air, the
when weather and
Therefore the value of
water vapour is not
included in the
composition of air.
The gases in the air are
separated by fractional
The air is cooled until it
becomes a liquid at about -200
degrees centigrade. As it warms
up again the separate
substances boil at different
temperatures and can be
Melting point is the
temperature at which
a substance changes
from a solid to a liquid.
Boiling point is the
temperature at which a
substance changes from
a liquid to a gas.
Carbon dioxide has
reduced due to:
Dissolves in oceans.
Used to form the
shells/skeletons of marine
Locked up as
Locked up as fossil fuels.
Releasing oxygen in photosynthesis.
Nitrogen has increased due to:
Ammonia reacted with oxygen.
Bacteria/micro-organisms release nitrogen.
Water vapour has decreased due
to earth's temperature cooling as
well as water vapour condensing
and forming the oceans.
EARTHQUAKES AND VOLCANOES
volcanoes occur at
Heat from radioactive
processes in the core
causes convection currents
in the mantel which make
the plates move
move slowly but
sudden release of
strain energy causes
Scientists cannot accurately
predict when earthquakes
and volcanic eruptions will
occur because they can't be
What is happening
under the crust.
We cannot measure the forces.
When the forces reach their limit.
LIFE ON EARTH
Scientists are unsure how life on
earth started, however there are
many theories to explain how.
On early earth energy from sun, volcanoes or
lightening could have formed a "primordial soup":
oceans filled with a dilute solution of complex
organic molecules needed for life (amino acids).
The Miller-Urey experiment demonstrated that
amino acids could be made from the interaction of
hydrocarbons, ammonia and lightning.
Other theories suggest that life
started in space and was brought
to earth on comets, asteroids and