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Slide 1

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P1 Earth + the
Revision Notes…read more

Slide 2

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Earth + Space
Universe 14000myo
Galaxies ­ star
collections (Milky Way)
Solar system 5000myo
Created when dust and
gas pulled together by
gravity making clumps....
Sun is a star;
Made of hot gases…read more

Slide 3

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Dating the Earth
Rocks change very slowly due to erosion
and weathering.
Deeper the rock the older it is.
Radioactive dating;
Estimating the age of something like a rock by
measuring its radioactivity.
Also used on fossils (stony remains of an animal or
plant that lived millions of years ago).…read more

Slide 4

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Continental Drift
Originally described in 1915 by Alfred
Wegener (a meteorologist).
Idea that crust consists of a number of
tectonic plates which constantly move
Either away from, against or alongside each other.
Move between 2 and 20cm a year.
Now measured using satellites.…read more

Slide 5

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Wegener's Theory
In favour;
Fossils and rocks Against;
identical in Africa and You cannot see or feel
South America. continents moving.
Continents fit like a Land bridge could
jigsaw. have joined Africa and
Land bridge; S America.
Rocks lightest at the
top cannot sink into Wegener not a
heavier rocks. geologist (rock expert).…read more

Slide 6

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Seafloor Spreading
Theory now accepted after initial criticism.
Proved by mapping major oceans. Ridges
(mountain chains) down the centre of oceans
emit molten lava which cools to make new rock
(Constructive margin).
This is constantly pushed along to make way for
newer rock. Shown by magnetic stripes of the
Earths field direction of the time.
Discovered by scientist Fred Vine (1963).…read more

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