Destructive Boundaries

• There are 3 types of Destructive Boundary.
• There are 3 types of destructive boundaries which are Oceanic-Continental, Continental-Continental and Oceanic-Oceanic
• When an Oceanic and Continental plate collide, the heavier oceanic plate will be subducted ie. it will sink into the mantle and melt.
• As subduction occurs the continental plate is pushed upwards to form Fold mountains.
• The Andes in south America have formed where the Nazca Plate has subducted under the South American Plate.
• The sinking oceanic plate melts in the mantle to create an excess of magma.
• • Some of this magma may push its way to the surface to create volcanoes.e.g. Mount Saint Helens in the USA.
• Faulting also happens at destructive plate boundaries and may result in earthquake activity.
• A deep ocean trench marks the place where one plate is subducted beneath the other.
• Trenches mark all subduction zones and may be thousands of kilometres long and 8 – 11 km deep e.g. Mariana Trench.