Physical processes at plate margins

Cards (7)

Constructive margin
Where 2 plates move apart, magma forced its way to the surface. As it breaks the crust, it causes mild earthquakes
Constructive margin
The magma is very hot and fluid allowing the lava to flow a long way before cooling. This results in typically broad and flat shield volcanoes
Conservative margin
Where 2 plates move past wach other at different rates (e.g San Andreas Fault, California), friction between them builds stresses and triggers earthquakes when they slip
Conservative margin
There are no volcanoes because there is no magma
Destructive margin
Where 2 plates move towards each other, dense oceanic plate is subducted beneath the less dense continental plate. Friction between them causes strong earthquakes
Destructive margin
The sinking oceanic plate creates sticky, gas-rich magma. This results in steep-sided composite volcanoes which erupt violently
Destructive margin
Where 2 continental plates meet, there is no subduction, so there is no magma to form volcanoes. The crust crumples and lifts to form fold mountains (e.g. Himalayas). Powerful earthquakes can be triggered