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C1 7.2a – Student worksheet
Evidence for plate tectonics
These 18 statements show evidence for the theory of plate tectonics.
1
Similar fossils have been found on different continents.
2
Measurements using satellites have shown that the UK and the USA are getting further apart
by about 2.5 cm every year.
3
The oldest rocks found on the continents are nearly 4000 million years old.
4
From 1960 onwards, seismometers have been used to accurately work out where earthquakes
start. Most earthquakes occur in narrow belts around the world.
5
Samples of the sediment on the ocean floor have been taken all over the world. There is
nowhere that the sediment is thick enough to have built up for over 4 billion years.
6
The fossils on some continents show that their climate must have been very different in the
past.
7
Similar rocks are found at the edges of different continents.
8
Coal is found in areas that are very cold today. The plants that eventually form coal only grow
in very warm climates.
9
There are very deep oceanic trenches near the edges of some continents.
10 Earthquakes can occur on the surface of the Earth or deep within it. The deepest earthquakes
happen near the oceanic trenches.
11 The Himalaya mountains are growing taller by about 5 mm each year.
12 Surveys of the ocean floor show tat there are very long mountain ridges beneath the oceans.
13 Rock samples have been taken from the ocean floor. These show that the rocks are much
younger near the oceanic ridges than they are near the edges of the oceans.
14 The edges of the continents seem to fit together.
15 Rocks in tropical areas show marks left by glaciers.
16 The oldest sea floor is no more than 200 million years old.
17 Similar fish fossils are found in freshwater sediments on both sides of the Atlantic.
18 The magnetic arrangement of the rocks shows the same pattern on both sides of the ocean
floor ridge.
Below are six ideas about plate tectonics. Which of the pieces of evidence in the numbered
statements above supports each of these six ideas? Match the statements to the ideas. Note
that some of the statements fit for more than one of the ideas.
A
The continents must have been joined at some time in the past.
B
New crust is being formed at the undersea ridges.
C
The continents must have been in different place on the Earth in the past.
D
Crust is being destroyed at the undersea trenches, where one plate goes under another.
E
The plates are still moving.
F
Oceanic crust (crust under the sea) has been formed more recently than most continental crust
(crust not under the sea).
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