Geography: a Destructive Plate Margin and Constructive Plate Margin.

Plate Boundary

Diagram

Description

Example

Constructive plate boundaries

Constructive plate boundaries occur when two plates move away from each other

North American and Eurasian Plate

Destructive plate boundaries

Destructive plate boundaries occur when an oceanic plate is forced under a continental plate

Pacific Plate and the Eurasian Plate

Conservative plate boundaries

Conservative plate boundaries occur when two plates slide past each other.

North American Plate and the Pacific Plate

Collision plate boundaries

Collision plate boundaries occur when two continental plates move towards each other.

Indo-Australian and the Eurasian Plate

When you get plates moving apart from each other i.e. the South American plate and the African plate. These causes a gap were magma rises and we get a volcano. This starts in the sea but after constant eruptions the lava builds up and solidifies. This then builds up until the volcano gets higher and higher.

When an oceanic plate pushes against a continental plate this causes the oceanic plate to be pushed down and be melted in the mantle then the magma made from the melting of the oceanic plate is pushed up through a gap to make a volcano.

SOME FACTS!

. Measuring 30 to 75 km thick the continental crust is thicker than the oceanic crust, which is only 3 to 10 km thick.

2. The most ancient rocks, dated to more than 4 billion years, are found in the central regions of the continents.

3. In the Pacific plate, the most ancient parts are only about 200 million years old. This crust is formed when two oceanic plates move apart from each other, causing magma to ooze up from the mantle. This magma solidifies to form volcanic rock.

4. The continental plate is lighter then the oceanic plate.