What happens at plate boundaries?

objectives To know and understand what happens at different plate boundaries

Plate movements Plates move because they float on convection currents (mantle). Plates move in many different directions.

Constructive plate boundary At a constructive plate boundary, two plates move apart. As the two plates move apart, magma rises up to fill the gap. This causes volcanoes. However, since the magma can escape easily at the surface the volcano does not erupt with much force. Earthquakes are also found at constructive boundaries. An example of a constructive boundary is the Mid-Atlantic Ridge.

Constructive plate boundary

Mid-Atlantic ridge Sea Floor Spreading! Did you know that the ocean floor in the Atlantic is growing by 3cm per year? Which of the following pairs of continents are moving further away from each other? Europe and Africa Europe and North America South America and North America

How fast do plates move? Tectonic plates move at different rates. The Nazca and Pacific plates are moving apart at a rate of 18cm per year while the Eurasian and North American plates are moving apart at a rate of 3cm per year. To the nearest metre, how far will the Nazca and Pacific plates have moved over the next 200 years? 6 metres 36 metres 928 metres 200 metres

Destructive plate boundary A destructive plate boundary is found where a continental plate meets an oceanic plate. The oceanic plate descends under the continental plate because it is denser. As the plate descends it starts to melt due to the friction caused by the movement between the plates. This melted plate is now hot, liquid rock (magma). The magma rises through the gaps in the continental plate. If it reaches the surface, the liquid rock forms a volcano.

Destructive plate boundary

Destructive plate boundary Match the labels to the letters. F E A B C D 1.oceanic plate 2. The oceanic crust sinks under the less dense continental crust. 3. The oceanic crust melts and rises. 4. continental crust 5. explosive volcanoes 6. mantle

Collision plate boundary Collision boundaries occur when two plates of similar densities move together (i.e. a continental plate and a continental plate). This causes the material between them to buckle and rise up, forming fold mountains. The Himalayas are an example of a chain of fold mountains. They have been formed by the African plate colliding into the Eurasian plate.

Collision plate boundary

Conservative plate boundary Conservative plate boundaries exist where two plates do not directly collide but slide past each other along a fault (weakness). No volcanoes are found along these plate boundaries, but earthquakes do occur. An example of such a boundary is the San Andreas Fault in California.

Conservative plate boundary

Plate definitions