What are constructive and destructive plate boundaries?
Constructive: 2 plates moving apart
Destructive: oceanic plate under continental plate
Constructive plate boundaries are when there are two plates moving apart from each other. They are called constructive plates because when they move apart, magma rises up in the gap- this forms volcanoes and eventually new crust. One example is the Mid-Atlantic Ridge, where the gap can be found in Thingvellir, Iceland.
Destructive plate boundaries are when oceanic and continental plates move together. In these places, the oceanic plate is forced, or subducted, under the continental plate. The friction from this causes melting of the oceanic plate and this can lead to earthquakes and/or volcanic eruptions. An example of a destructive plate boundary is where the Nazca plate is forced under the South American Plate.