# Tectonic Plate Margins

Updated on February 28, 2017

## Constructive/Divergent

A constructive margin can also be called a divergent margin. This type of plate margin occurs when the two plates are moving away from each other, i.e. they are moving in opposite directions to each other. There is no collision at a constructive plate margin.

The reason why it is called a constructive plate margin, is because as the two plates move away from each other, magma below the surface starts to rise up through the gap caused the plates moving. So the magma is rising up and breaks through the surface, and what happens is after the magma breaks through the surface it starts to cool down and solidify there, creating new land. Therefore this type of plate margin constructs new land and that's why it is called a constructive plate margin. It is also known as a divergent margin because put simply, the plates are moving away from each other, which is what divergent means.

## Destructive/convergent

A destructive plate margin is where the two plates are moving towards each other and will collide. This usually happens with an oceanic plate and continental plate. These two types of plates have different characteristics which are important in the subduction process. Subduction is where the denser oceanic plate gets subducted (pushed under) the less dense continental plate.

The denser oceanic plate gets forced under the less dense continental plate and this causes friction. The friction causes melting of the oceanic plate and may trigger earthquakes. Magma rises up through cracks and erupts onto the surface, and this is how some volcanoes are formed.

Collision zones occur when two continental plates collide with each other, and as these are the same type of plate when they collide they push into each and rise up to create Fold Mountains. Eventually after the two continental plates keep pushing into each other one will give way and be forced under the other one. Most of the famous mountain ranges are fold mountains, e.g the Alps, Himalaya's, Rockies and Andes are all example of fold mountain ranges.

Oceanic plate
Continental plate
Denser
Less dense
Basalt
Granite
Beneath oceans
Beneath land
Table showing the differences between oceanic and continental plates

## Conservative/transform

At this plate margin the two plates are sliding next to each other in either opposite directions, or in the same direction at different speeds. Either way friction is formed as the two plates rub against each other and a sudden movement can release this friction as shock-waves and this is how some earthquakes are formed.

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