Plate Boundaries and Landforms Flashcards
Describe a constructive / divergent plate boundary.
- An oceanic and oceanic plate boundary. Both are pulling away from one another.
Landforms occur as the plates move apart and magma rises between the plates.
Both volcanoes and small earthquakes can occur here.
Describe a destructive plate boundary.
Can occur at an oceanic and oceanic plate boundary of oceanic and continental plate boundary.
The denser oceanic plate sinks and causes friction between plates.
Big earthquakes here as friction builds when the plate subducts.
Volcanoes can form as the subducting plate melts and the magma forces its way up.
Describe a collision plate boundary.
Occurs at continental and continental plate boundary.
No subduction occurs.
The plates collide and crust piles up forming fold mountains.
No earthquakes or volcanoes.
Examples - Alps, Himalayas
Describe a conservative plate boundary.
Occur at any plate boundary.
Plates moving alongside each other - either same direction, different speeds of different directions.
Causes earthquakes. No volcanoes or subduction.
Example - San Adreas.
How do magma plumes form?
Also known as mantle plumes or hot spots.
They are volcanic landforms that are away from any plate boundaries - intra-plate.
Form when an oceanic plate moves over the static magma plume which can cause a chain of islands to form. When magma breaks the surface of the sea islands can form.
Example - Hawaii.
How do ocean ridges form?
Form when plates move apart in oceanic areas, magma rises to fill the gap and forms a ridge. Volcanic activity also occurs along the ridge.
Example - Surtsey to the south of Iceland.
How do deep sea ridges form?
Form due to the oceanic plate at destructive plate boundaries.
Example - Mariana Trench, 11,000 m long
What are island arcs?
Volcanic islands which form at oceanic on oceanic plate boundaries.
The undersea volcanoes break the surface and become islands.
