Transcript The Crust

B
1.
A
Write the correct terms for
A, B, C, D
C
D
2.
On the following slide, pick 3 statements that
apply to the core, 3 applying to the mantle
and 3 applying to the crust.
High temperatures near the core are believed
to be responsible for the generation of
convection currents.
Approximately the size of Mars.
Thinnest, coolest and least dense layer.
Varies in thickness from 5 to 70 km.
Separated from the mantle by the
Mohorovijic (Moho) discontinuity.
Most of the mantle (asthenosphere) acts like it is semimolten.
Surrounded by semi-molten outer core.
Temperature over 6000˚C.
The most dense part of the planet.
Made up of rocks rich in iron and nickel.
The inner core is solid.
Separated from the core by the Gutenburg discontinuity.
Starts about 2900km down.
Rocks are rich in silicon, oxygen,
aluminium, potassium and sodium
Temperatures near the core reach 5000˚C.
Centre is 6350km down.
Largely composed of silicate rocks rich in iron and magnesium.
Upper mantle (close to the crust) is rigid and together with the crust forms the
LITHOSPHERE.
3.
What is the difference between the lithosphere
and the asthenosphere?
4.
Which is thicker?
Continental crust or oceanic crust?
5.
Which is older?
Continental crust or oceanic crust?
6.
Which is more dense?
Continental crust or oceanic crust?
7.
What so SIMA and SIAL stand for?
Which type of crust does each abbreviation
apply to?
8.
....... million years ago all the continents were
joined together to form one “supercontinent”
called .............
Fill in the blanks!
9.
In modern times, why
might it be difficult to
make the shapes of the
continents back
together?
10.
Give an example for each of the following types
of evidence supporting plate tectonics theory:
Geological evidence
Climatological evidence
Biological evidence
11.
What occurs in the asthenosphere to cause
plate movement?
12.
Name the three main types of plate boundary:
-
13.
• Where plates move apart in oceanic areas
they produce.....-.............. ....................
• Where they move apart in continental crust
areas they produce ........... ................. .
14.
• Name the oceanic ridge on which the country
Iceland has been formed.
15.
What is the geographical
term for the features the
arrows are pointing to?
16.
Name 3 features that are commonly created
during Oceanic-continental convergence.
-
17.
Name the two main features associated with
Oceanic - oceanic convergence.
-
18.
Think of a location where two continental plates
have collided.
Name the two plates involved and any feature
that were created as a result of the collision.
19.
Give an example of a conservative plate margin.
List 2 facts about it:
-
20.
“Volcanic activity only occurs at plate
boundaries.”
True or false?
B = Mantle
1.
A = Crust
Write the correct terms for
A, B, C, D
(4 marks)
C = Outer
core
D = Inner
core
2.
On the following slide, pick 3 statements that
apply to the core, 3 applying to the mantle
and 3 applying to the crust.
High temperatures near the core are believed
to be responsible for the generation of
convection currents.
Approximately the size of Mars.
Thinnest, coolest and least dense layer.
Varies in thickness from 5 to 70 km.
Separated from the mantle by the
Mohorovijic (Moho) discontinuity.
Most of the mantle (asthenosphere) acts like it is semimolten.
Surrounded by semi-molten outer core.
Temperature over 6000˚C.
The most dense part of the planet.
Made up of rocks rich in iron and nickel.
The inner core is solid.
Separated from the core by the Gutenburg discontinuity.
Starts about 2900km down.
Rocks are rich in silicon, oxygen,
aluminium, potassium and sodium
Temperatures near the core reach 5000˚C.
Centre is 6350km down.
Largely composed of silicate rocks rich in iron and magnesium.
Upper mantle (close to the crust) is rigid and together with the crust forms the
LITHOSPHERE.
3x3
The Core
9 marks
• Approximately the size of Mars
• Starts about 2900km down
• Centre is 6350 km down
• The most dense part of the planet
• Made up of rocks rich in iron and nickel
• Core temperature over 6000oC
• Outer core is semi-molten/liquid (only part of the planet which is!)
• Inner core is solid
The Mantle
• Separated from the core by the Gutenburg discontinuity
• Largely composed of silicate rocks rich in iron and magnesium
• Upper mantle (close to the crust) is rigid and together with the crust forms the lithosphere
• Most of the mantle (asthenosphere) acts like it is semi-motlen.
• Temperatures near the core reach 5000oC
• High temperatures near the core are believed to be responsible for the generation of convection
currents.
The Crust
• Thinnest, coolest and least dense layer.
• Rocks are rich in silicon, oxygen, aluminium, potassium and sodium
• Separated from the mantle by the Mohorovijic (Moho) discontinuity.
• Varies in thickness from 5 to 70 km
3.
What is the difference between the lithosphere
and the asthenosphere? (1 mark)
• Lithosphere: consists of the crust and the rigid
upper section of the mantle, approximately 8090km thick. Divided into seven large plates and a
number of smaller ones.
• Asthenosphere: the semi-molten mass below the
lithosphere on which the plates float and move.
Beneath the asthenosphere is the rest of the
mantle, which is completely solid.
4.
Which is thicker?
Continental crust or oceanic crust?
Continental (30-70km)
Oceanic (6-10km)
(1 mark)
5.
Which is older?
Continental crust or oceanic crust?
Continental (over 1,500 million years)
Oceanic (less than 200 million years)
(1 mark)
6.
Which is more dense?
Continental crust or oceanic crust?
Oceanic (heavier)
Continental (lighter)
(1 mark)
7.
What do SIMA and SIAL stand for?
Which type of crust does each abbreviation
apply to?
SIMA = silicon, magnesium, oxygen (oceanic)
SIAL = silicon, aluminium, oxygen (continental)
(3 marks)
8.
....... million years ago all the continents were
joined together to form one “supercontinent”
called .............
Fill in the blanks!
8.
250 million years ago all the continents were
joined together to form one “supercontinent”
called Pangaea
(2 marks)
9.
In modern times, why
might it be difficult to
make the shapes of the
continents back
together?
• There are differences in
modern and ancient
coastal morphologies.
• Variations in sea level.
( 2 marks)
10.
Give an example for each of the following types
of evidence supporting plate tectonics theory:
Geological evidence
Climatological evidence
Biological evidence
(3 marks)
Geological evidence
• The Appalachian Mountains of eastern North
America are thought to link to the
Caledonides of Ireland, Britain, Greenland,
and Scandinavia and the Anti-Atlas Range in
Morroco.
Climatological evidence
• Coal deposits that would have been formed in tropical climate
conditions are found in places that do not have a tropical
climate. Therefore, they must have drifted. E.g. Antarctica
Biological evidence
• Mesosaurus remains were found in southern Africa and eastern South
America, two far away places. Mesosaurus was a freshwater animal,
and could not have crossed the Atlantic Ocean, this indicates that the
two continents used to be joined together.
• Marsupials are only found in Australia because it drifted away from the
main supercontinent before the predators that wiped them out
elsewhere had migrated there
11.
What occurs in the asthenosphere to cause
plate movement?
CONVECTION CURRENTS!
(1 mark)
12.
Name the three main types of plate boundary:
• CONSTRUCTIVE /Divergent boundaries -- where new crust
is generated as the plates pull away from each other.
• DESTRUCTIVE /Convergent boundaries -- where crust is
destroyed as one plate moves under another.
• CONSERVATIVE /Transform boundaries -- where crust is
neither produced nor destroyed as the plates slide
horizontally past each other.
(3 marks)
13.
• Where plates move apart in oceanic areas
they produce.....-.............. ....................
• Where they move apart in continental crust
areas they produce ........... ................. .
• Mid-oceanic ridges
• Rift valleys
(2 marks)
14.
• Name the oceanic ridge on which the country
Iceland has been formed.
• Mid-Atlantic Ridge!
(1 mark)
Transform faults!
(1 mark)
15.
What is the geographical
term for the features the
arrows are pointing to?
16.
Name 3 features that are commonly created
during Oceanic-continental convergence.
- Deep ocean trenches
- Fold mountains
- Volcanic arcs (volcanoes)
(3 marks)
Rocks scraped off the descending plate
and folding of the continental crust
create young fold mountain chains on
edge of the continental mass. E.g the
Andes.
Deep ocean trenches are found along
the seaward edge of destructive
margins. They mark where one plate
begins to descend beneath another and
can reach great depths. E.g. Peru-Chile
trench, 8km deep
As it is less dense
than the
surrounding
asthenosphere, the
molten material
begins to rise up
through fissures
and by burning their
way through
overlying rock.
Eventually these
reach the surface to
form volcanoes.
The lava has a viscous nature (flows less
easily). This creates complex , composite,
explosive volcanoes. If the eruptions take
place off shore, a line of volcanic islands
known as an island arc can appear
Benioff zone – the further the rock
descends, the hotter the surroundings
become. This, together with the heat
generated from friction, begins to melt
oceanic plate into the magma.
17.
Name the two main features associated with
Oceanic - oceanic convergence.
- Ocean trenches
- Volcanic islands arcs
(2 marks)
18.
Think of a location where two continental plates
have collided.
Name the two plates involved and any features
that were created as a result of the collision.
(3 marks)
Himalayas
Causing Mt Everest to rise
by up to 3cm a year.
Indo-Australian Plate
Moving north and east
Approx. 5.8cm/year
Eurasian Plate
(rigid)
In parts the Indo-Australian plate is being pushed under to form the mountain
roots up to 70km deep.
This movement causes great stresses which are released by earthquakes.
Often extremely violent and destructive. E.g. Sichuan, 2008 – China, 80,000
deaths.
19.
Give an example of a conservative plate margin.
List 2 facts about it:
- San Andreas Fault
- Pacific plate moving north-westwards at
6cm/year.
- The North American plate moves northwestwards by 1cm/year
(3 marks)
The San Andreas Fault.
• California
• Although both plates are moving north-west, the Pacific plate
moves faster, giving the illusion that they are moving in opposite
directions.
• Los Angeles could eventually be on an island off the Canadian coast.
20.
“Volcanic activity only occurs at plate
boundaries.”
True or false?
FALSE!
Hot spots!
(1 mark)
Total:
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