Landforms Associates With Plate Movements Flashcards
The movement of plates are responsible for production of what ?
Ocean ridges
Rift valleys
Deep sea trenches
Island arcs
Young fold mountains
Volcanoes
What are ocean ridges ?
Longest continuous uplifted feature on surface of planet .
How are ocean ridges formed?
When 2 plates moved apart in oceanic areas.
Space between the plates is filled with basaltic lava upwelling from below to fork ridge.
Volcanic activity also occurs along here which form submarine volcanoes - Surtsey Iceland
Where do Rift valleys form ?
When plates moves apart on continental areas
Now to Rift valleys forms
Brittle crust fractures as section of it move apart.
Crust drop down between parallel fault to form valley.
Area between 2 parallel Rift valleys form upstanding block known as a Horst.
How are deep sea trenches formed ?
When oceanic and continental plate meet the denser oceanic plate subduction underneath lighter continental plate.
Downward movement of oceanic plate forms very deep part of the ocean known as a trench.
(Also when 2 oceanic plates converge - Marianas trench)
Example of deep sea trench?
Western coast of South America.
Nazca plate is subducting underneath South American plate forming Peru chile trench.
How are island arcs formed ?
During subduction, descending plate encounters hot surrounding and this coupled with heat generated from friction begins to melt plate.
As this material is less dense than surrounding asthenosphere it begins to rise towards surface as plutons of magma.
Eventually reaches surfaces forming complex composite volcanoes.
If this take place offshore then a line of volcanic island form - island arcs
Young fold mountain formation
2 continental plates have lower density so not much subduction occurs when plates meet.
As they meet the sediments between them are forced up into fold mountains - no subduction- no volcanic activity.
ExmPle of fold mountain range
Himalayas - indo Australian plate and Eurasian plate
