Unit 2 - Tectonics Flashcards
What are the names for the 4 layers in the Earth?
- Crust
- Mantle
- Outer core
- Inner core
State the following for the inner core:
- temperature
- thickness/radius
- What it mainly consists of
- around 5,200° C
- radius around 3,485km
- a hot dense ball of (mostly) iron
State the following for the outer core:
- temperature
- thickness
- What it mainly consists of
- 4,500° - 5,500° C
- thickness of about 2,200km
- mostly liquid iron and nickel
State the following for the mantle:
- temperature
- thickness
- What it mainly consists of
- 500-900°C
- thickness of about 2,886km
- it is a silicate rocky shell
State the following for the crust:
- temperature
- thickness
- What it mainly consists of
- 200-400° C
- average thickness of 0-60km
- solid rock
Explain how a convergent plate boundary forms fold mountains.
- Plates move together and collide
- Very violent volcanoes (e.g. Mt St Helens, USA) and Mt. Etna (Sicily) and earthquakes occur.
- Subduction zones form due to downward movement of the dense oceanic crust into the mantle, beneath the less dense continental crust.
- Fold mountains (e.g. the Alps and the Himalayas) can form when both plates are pushed upwards by the force of the collision.
What type of plate boundary is Mt Laki (Iceland) on?
Divergent plate boundary (accept constructive)
Explain how a divergent plate boundary forms ocean ridges e.g. the Mid-Atlantic Ridge.
- Plates move apart.
- Less violent volcanoes and earthquakes occur.
- New sea floor is created at the mid-ocean ridges (e.g. the Mid-Atlantic Ridge) as magma rises up through the ridge and solidifies.
Give a location affected by a conservative boundary.
Many locations accepted, examples are:
- San Andreas Fault
- Alphine Fault (N, Zealand)
- North Anatolian Fault (Turkey)
Explain how earthquakes can occur with a conservative plate boundary.
- Plates slide past each other.
- No crust is destroyed or created, therefore no volcanoes are formed.
- Plates can ‘stick’; this increases pressure which can be released as violent earthquakes.
What is the difference between a collision and convergent plate boundary?
Challenge: Give a location affected by a collision boundary if you can.
A collision boundary has nearly of the same characteristics as a convergent boundary but instead of an oceanic and continental plate being involved, it’s a continental and continental plate e.g. Indo-Australian Plate and Eurasian Plate.
Challenge: A mountain range affected by a collision boundary is the Himalayas.
GIve one general characteristics about a volcano.
- A volcano is formed by eruptions of lava and
ash, with the lava later harding to become new
rock
OR
- Volcanoes usually are cone-shaped and are
mountains or hills that have become active.
OR
- Volcanic eruptions can happen at convergent
and divergent boundaries but not conservative
boundaries
OR
- Some volcanoes happen underwater - like the
Mid-Atlantic Ridge
Explain how a volcano is formed.
- Magma rises through cracks or weaknesses in
the Earth’s crust.
2.Pressure builds up inside the Earth.
3.When this pressure is released, eg as a result of
plate movement, magma explodes to the
surface causing a volcanic eruption.
4.The lava from the eruption cools to form new
crust.
5.Over time, after several eruptions, the rock
builds up and a volcano forms.
Give 4 features located inside a volcano.
• The magma chamber is a collection of magma
inside the Earth, below the volcano.
• The main vent is the main outlet for the magma
to escape.
• Secondary vents are smaller outlets where the
magma escapes.
•The crater is created after an eruption blows off
the top of the volcano
Briefly outline how an eruption occurs,
An eruption occurs when pressure in the magma chamber forces magma up the main vent, towards the crater at the top of the volcano. Some magma will also be forced out of the secondary vent at the side of a volcano.
