Constructive
A Constructive plate boundary can also be known as a tensional or divergent boundary. This is when two plates are moving apart from one another. These are predominately found under the oceans. This therefore allows magma from the mantle to rise and cause shield volcanoes.
Two Examples of this is the South American and the African Plate and the other is the Eurasian Plate and the North American Plate. This can be seen in the bottom left image of the different plates found on the earths crust and the way in which they move.
As the plates move apart (very slowly), magma rises from the mantle. The magma erupts to the surface of the Earth. This can also be accompanied by earthquakes. When the magma reaches the surface, it cools and solidifies to form a new crust of igneous rock. This process is repeated many times, over a long period of time. Eventually the new rock builds up to form a volcano.
The Mid Atlantic Ridge
Located along the floor of the Atlantic Ocean and is part of the longest mountain range in the world.
In the North Atlantic, it separates the Eurasian and North American Plates, whereas in the South Atlantic it separates the African and South American Plates. The Ridge extends from a junction with the Gakkel Ridge (Mid-Arctic Ridge) northeast of Greenland southward to the Bouvet Triple Junction in the South Atlantic.
Here, chains of underwater volcanoes have formed along the plate boundary. One of these volcanoes may become so large that it erupts out of the sea to form a volcanic island, eg Surtsey and the Westman Islands near Iceland.
Two Examples of this is the South American and the African Plate and the other is the Eurasian Plate and the North American Plate. This can be seen in the bottom left image of the different plates found on the earths crust and the way in which they move.
As the plates move apart (very slowly), magma rises from the mantle. The magma erupts to the surface of the Earth. This can also be accompanied by earthquakes. When the magma reaches the surface, it cools and solidifies to form a new crust of igneous rock. This process is repeated many times, over a long period of time. Eventually the new rock builds up to form a volcano.
The Mid Atlantic Ridge
Located along the floor of the Atlantic Ocean and is part of the longest mountain range in the world.
In the North Atlantic, it separates the Eurasian and North American Plates, whereas in the South Atlantic it separates the African and South American Plates. The Ridge extends from a junction with the Gakkel Ridge (Mid-Arctic Ridge) northeast of Greenland southward to the Bouvet Triple Junction in the South Atlantic.
Here, chains of underwater volcanoes have formed along the plate boundary. One of these volcanoes may become so large that it erupts out of the sea to form a volcanic island, eg Surtsey and the Westman Islands near Iceland.