Restless Earth Flashcards
what are the 4 layers of earth?
Crust Mantle outer core inner core
what are tectonic plates?
sections of the earths crust.
how do tectonic plates move?
the Earths crust is unstable because the plates are moving due to rising hot currents called convection currents within the mantle. These push and pull the plates.
what plate are we on?
The Eurasion Plate
What are the two types of crust?
oceanic continental
give two differences between the oceanic and continental crust
Continental crust is thicker than the oceanic. Oceanic is under water
which countries are most affected by the movement of tectonic plates
countries on a plate boundary
give another name for a constructive plate boundary
Divergent plate boundary
what happens at a constructive plate boundary?
at a constructive plate boundary, two plates move apart, magma rises up to fill the gap. this causes volcanoes. However, since magma can escape easily at the surface the volcanoes do not erupt with much force.
Name an example of a constructive Boundary
Mid-Atlantic ridge
Give an example of a volcano found at a constructive plate boundary
Surtsey, Iceland
give another name for a convergent plate boundary
Destructive plate boundary
What happens at a destructive plate boundary?
a destructive plate boundary is found where a continental plate meets an oceanic plate. At a destructive plate boundary the plates are moving together. The denser oceanic crust subducts beneath the lighter continental crust. The oceanic crust sinks into the mantle where it melts in the subduction zone. The energy may be released as an earthquake and the molten magma may rise upwards casing a volcanic eruption. The continental crust becomes fold mountains.
What can be found at a constructive plate boundary?
Earthquakes and volcnaoes
What can be found at destructive plate boundaries?
Earthquakes, Volcanoes, deep ocean trenches and fold mountains
Give an example of a deep ocean trench
Marianas Trench
What are the uses of a deep ocean trench?
Continental shelf in the ocean can be used for fishing and the drilling of oil and gas.
Give another name for a transform plate boundary
Conservative plate boundary
What happens at a conservative plate boundary?
Here the plates slide past each other either in the same or opposite directions. The two plates meet at a boundary and pressure builds up until the two plates suddenly jerk past each other. This causes an earthquake.
Give an example of a transform plate boundary
The San Andreas Fault, California, USA
What can be found at a conservative plate boundary?
Only earthquakes
What happens at a collisional plate boundary?
Collisional plate boundaries occur when two plates of similar densities move together. This causes the material between them to buckle and rise up, forming fold mountains.
Give an example of fold mountains and the plates they are found on
The Himalayas are an example of chain fold mountains. They have been formed by the Indian plate colliding into the Eurasian plate.
Which plate boundary is this?
Destructive
What plate boundary is this?
Constructive
Which plate boundary is this?
Conservative
Which plate boundary is this?
Collisionsal
What is your fold mountain case study?
The Alps
What countries are the Alps in?
France, Switzerland, and Italy
How are fold mountains formed?
Where an area of sea separates two plates, sediments settle on the sea floor in depressions called geosynclines. These sediments gradually become compressed into sedimentary rock.
When the two plates move towards each other again, the layers of sedimentary rock on the sea floor become crumpled and folded.
Eventually the sedimentary rock appears above sea level as a range of fold mountains.
What are the human activities in the alps?
- Transhumance Farming
- Tourism
- Forestry
- Hydro Electric Power (HEP)
What is transhumance farming?
This is a type of dairy farming. It involves people moving the animals to different places depending on the seson. In summer the cows go to the top of the high Alps to graze. Cable cars are used to bring milk to the dairies on the valley floor. The milk is used to make butter and cheese. In winter they buy additional feedstuff so the cows can stay on the valley floor.
How do they use forestry in the Alps?
Coniferous trees cover most of the slope, especially the north facing ones. People chop these trees down to get the wood. Wood is the main building material and winter fuel in Alpine lands as there is so much of it. Timber that isn’t used for construction is made into pulp and then paper.
How do they use tourism in the Alps?
Tourism is one of the main industires in the Alps. The mountains attract people as they can do various sports in winter and summer. In winter people ski and snowboard. In summer people walk, climb, base jump, and paraglide.
;+How do they use Hydro Electric Power in the Alps?
The steep slopes, high amount of precipitation, and melting glaciers mean there are fast flowing rivers. These rivers are ideal for generating HEP. Narrow valleys are easy to dam and lakes store water. Its a cheaper power source for the locals. Industries and towns and cities use HEP as a power source.
How have people adapted to living in The Alps?
- They have put hairpin bends in the roads so they can easily navigate the steep slopes.
- The have made many parts of roads under tunnels/shelters to protect themselves from avalanches and rockfalls.
- They have put solid road markings to compensate for the poor visability due to fog.
- They have put barries round the high alpine roads so it is harder to drive off.
What are the problems wiht long road tunnels under mountains?
- They are expensive.
- They are a fire hazard.
- They take a long time to construct.
How are volcanoes formed at a destructive plate boundary? (SEEP)
First the crust moves towards another piece of the crust due to convection currents in the mantle moving the plates. As one crust is subducted beneath another piece of crust, the pressure is increased. As well as pressuer increasing, friction also increases. This means that the temperature of the rock goes up.
As the piece of crust is pushed under the less dense piece of crust it bends and as this happens, a zone of earthquakes is generated. As the oceanic crust subducts under the continental crust it forces the sea bed down with it as well as sea water. This creates deep ocean trenches. As the crust continues down it heats up even more and begins to melt. The melted rock is less dense than the surrounding rock and so rises. As it moves up it breaks through the crust and eventually a volcano froms on the surface.
As times goes on more eruptions happen and the volcano builds up layers of rock. This is repeated for millions of years and so a volcano is formed.
An example of a volcano at a destructive plate boundary is Mt. St. Helens
What are the two types of volcano?
Shield
Composite
What are the features of a shield volcano?
They from at a constructive plate boundary.
Can occur at hotspots e.g Hawaii.
Gentle sided.
Made from cooled lava.
Do not erupt as violently.
Continuously erupt.
Lava flows freely and far way, up to 25 miles.
Lava is runny, viscous with a low silica content.
E.g Mt. Kilauea, Hawaii, USA
What are the features of a composite volcano?
Destructive plate boundary.
Steep sided.
Erupts violently due to pressure building up and being released.
high silica content.
viscous and acidic lava that can’t flow far.
Can create a pyroclastic flow
Furthur blockages by rapidly hardening rock allows vents to be blocked.
E.g Mount St. Helens, USA
How are hotspot volcanoes formed? (SEEP)
A strong convection current breaks through weaknesses in the crust to begin to from a volcano on the sea floor. Eventually the volcano rises to the surface to srom active, shield volcanoes. As the convection currents cause the plates to move, the volcanic islad becomes extinct becuase it moves off the hotspot. Eventually the island is eroded by the sea and becomes very small. E.g Mt. Kilauea, Hawaii, USA.