Types of Plate Margin Flashcards
Where do constructive margins occur?
A constructive margin occurs where two plates are moving apart.
Name the two landforms that are created at constructive margins?
Ocean Ridge and Rift Valley
What are ocean ridges?
Where constructive plates are underwater, an ocean ridge form. For example, the Mid Atlantic Ridge is where the Eurasian plate and North American plate are moving apart.
How has Iceland been formed?
Underwater volcanoes erupt along mid ocean ridges and they can build up to be above sea level. Iceland has been formed by the build up of underwater volcanoes along the Mid Atlantic Ridge.
What are rift valleys?
Where plates diverge beneath land, rising magma causes the continental crust to bulge and fracture, forming fault lines. A the plate keep moving apart, the crust between parallel faults drop down to form a rift valley.
What are found around rift valleys?
Volcanos are found around rift valleys.
Where do destructive margins occur?
A destructive margin occurs where two plates are moving towards each other.
What happens when continental crust and oceanic crust converge?
The more dense oceanic crust is forced under the less dense continental crust (its subducted).
What does the subduction of the oceanic plate under the continental plate form?
It forms a deep sea trench.
What forms where the oceanic and continental plates meet?
Fold mountains. They’re made up of sediments that have accumulated on the continental crust, which are folded upwards along with the edge of the continental crust.
How are volcanos formed at a destructive plate margin where continental and oceanic crust converge?
The oceanic crust is heated by friction and contact with the upper mantle, which melts into magma. The magma is less dense than the continental crust above and will rise back to the surface to form volcanos.
How are earthquakes caused at a destructive margin where continental crust and oceanic crust converge.
As one plate moves under the other they can get stuck. This causes pressure to build up. When the pressure becomes too much the plates jerk past each other, causing an earthquake.
What happens when two oceanic crusts converge?
The denser of the two will be subducted, forming a deep sea trench and triggering earthquakes and volcanic eruptions.
How are island arcs formed?
Volcanic eruptions that take place underwater create island arcs - cluster of islands that sit in a curved line.
What happens when two continental crust converge?
Where two plates of continental crust move towards each other neither is subducted so there aren’t any volcanos - but the pressure that builds up between them can cause earthquakes.
