Download iii) structure - Junta de Andalucía

III) STRUCTURE
1
Look at the illustration of the different layers that make up the
Earth.
Complete the sentences below:
a) The ___________________ is in the centre of the Earth.
b) The
___________________ is the layer surrounding the
___________________.
c) The layer above the
___________________ is the
___________________.
d) The
___________________ covers the
___________________ . It
is the outer layer of the Earth.
2
Look at the illustration on
the left and complete the
sentences:
a) The crust is a thin
layer
between
5
and
_____ km thick.
b) The lower and the upper
mantle cover the core
and are about _____ km
thick.
c) The core is about _____
km thick.
The earth is made up of 4 distinct layers:
1. The inner core is in the centre of the earth and is the
hottest part of the earth. The inner core is solid. It is
made up of iron and nickel with temperatures of up to
5500°C.
2. The outer core is the layer surrounding the inner core. It
is a liquid layer, also made up of iron and nickel. It is
still extremely hot here, with temperatures similar to the
inner core.
3. The mantle is the widest section of the earth. The mantle is
made up of semi-molten rock called magma. In the upper parts
of the mantle the rock is hard, but nearer the core, the
rock is soft.
4. The crust is the outer layer of the earth. It is a thin
layer between 5-75 km thick. The crust is a solid rock
layer. We live on this layer.
3
Read the text on the preceding page and write the words “soft” and
“hard” into the correct circles.
inner
core
outer
core
Lower
mantle
Upper
mantle
4
Study this cross
section
of
the
Earth.
1) What layer
does the
black colour
represent?
2) Is this
layer the
same size
all around
the Earth?
Lithosphere
The crust and the upper parts of the mantle are called the
lithosphere. There are two types of lithosphere: Oceanic
lithosphere carries water. Continental lithosphere carries land.
Oceanic
lithosphere
is
typically
about
50-100
km
thick.
Continental lithosphere is about 150 km thick.
What does the illustration on the
left represent? Write the correct
names next to the numbers.
a. _________________
b. _________________
c. _________________
5
Asthenosphere
The asthenosphere is the
region
of
the
Earth
between 100 and 200 km
below the surface. It is
the weak or "soft" zone
in the upper mantle. It
lies
just
below
the
lithosphere.
Plate Tectonics
The lithosphere is broken up into pieces. These pieces are called
plates. Heat rising and falling inside the mantle creates
currents. These currents move the plates. The movement of the
plates, and the activity inside the earth, is called plate
tectonics. Plate tectonics cause earthquakes and volcanoes. The
point where two plates meet is called a plate boundary.
Earthquakes and volcanoes usually occur either on or near plate
boundaries.
Now go to the following website:
http://www.bbc.co.uk/schools/gcsebitesize/geography/index.shtml
Click on “plate tectonics”.
Now click on “Revise” (Plate Tectonics)
Then click on plates and plate boundaries.
Discuss
a) the different movements of the plates
b) the distribution of earthquakes and volcanoes
6