Transcript Earth structure

Earth Structure and Plate
Tectonics
By the end of this lesson you will:
• Know the structure of the Earth’s
interior
• Understand plate tectonics and their
movement
What is this?
 Digital Vision 9 (NT)
WALT What is the structure of the
Earth?
WILF
All students are able to recall the structure of the
Earth ( grade D )
Most students are to describe what are tectonic plates
and how they move by convection currents
( grade C )
Some students are able to explain continental drift
and what happens at plate boundaries ( grade B )
Starter
1. Which metals are found at the centre of
the Earth?
2. How thick is the Earth’s crust?
3. How were the Himalayan mountains
formed?
4. Where do we find volcanoes?
5. Why do earthquakes happen?
6. Who is Wegener?
Key Words
Core
crust
convection currents
mantle
tectonic plates
continental drift
The Earth’s Structure
Beneath the atmosphere the Earth consists of 3 main layers:
The Structure of the Earth
A thin crust 10-100km thick
A mantle – has the
properties of a solid
but it can also flow
A core – made of
molten nickel and iron.
Outer part is liquid
and inner part is solid
The average density of the Earth is much higher than
the crust, so the inner core must be very dense
What am I?
•
I am dense, very hot, made mostly of solid iron
and nickel.
Inner core
•
I’m iron and nickel too, but I’m liquid.
Outer core
•
I’m really very thin and am mostly silicon,
Crust
oxygen and aluminium
•
I’m a viscous semi-solid with convection
Mantle
currents circulating in me.
•
I just hang around on the outside.
Atmosphere
How am I doing?
Were you able to answer the questions?
YES ? Well done you have achieved WILF 1
All students are able to describe the
structure of the Earth ( grade D )
Tectonic plates
•
•
•
•
The crust is made of about twelve plates.
These are like big rafts floating on the semi-molten
mantle.
Convection currents within the mantle cause the
plates to move.
Although they only move about 2 cm/year this can
have huge effects over long periods of time.
Movement of the Lithosphere
crust
The Earth’s LITHOSPHERE (i.e. the _______)
is split
up into different sections called ________
tectonic plates:
These plates are moving apart from each other a
few centimetres every _______
due to the
year
convection
________ currents in the mantle caused by the
radioactive
________ decay of rocks inside the core.
Words – radioactive, crust, convection, tectonic, year
How am I doing?
Were you able to complete the sentences?
YES ? Well done you have achieved WILF 2
Most students are to describe what are
tectonic plates and how they move by
convection currents ( grade C )
Continental Drift
Introducing plate tectonics
Evidence for Continental Drift
The theory is supported by several
pieces of evidence.
For example, if we consider Africa and
South America there is:
– The “jig-saw fit”
– The similarities in the rock layers
from Africa and South America.
– Similarities in the type and age of
fossils.
– Evidence of related species that
definitely did not swim the Atlantic
Ocean!
Jig Saw fit
Similar rocks
and fossils
Task
Working in a pair
Write your own explanation for plate tectonics and
continental drift using the information given to
you by your teacher and text book
Include a section on what evidence is available to
support the idea of continental drift
WALT What is the structure of the
Earth?
WILF
All students are able to recall the structure of the
Earth ( grade D )
Most students are to describe what are tectonic
plates and how they move by convection
currents ( grade C )
Some students are able to explain continental drift
and what happens at plate boundaries
( grade B )
Plate boundaries
Activity
• Find the words
and write a
sentence about
how each one
has something to
do with plate
tectonics.
– Drift
– Earthquake
– Fossil
– Jigsaw
– Magma
– Pangaea
– Plates
– Subduct
– Volcano
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