Diverging plate boundaries

Diverging plate boundaries (also known as constructive plate boundaries)

They form when two of the Earth's plates move apart from one another.

Convection Currents - rising upwards towards the lithosphere move away from each other and pull the plates apart.

Divergent boundaries occur underneath both oceanic crust and continental crust

Why? - Core 6,000°c - magma in mantle -Cools- Thermal convection currents

Example- is between the North American and Eurasian plates

-Moves away from each other at a rate of roughly 2.5 cm per year.

Seafloor spreading, Rift valley

Seafloor spreading

Oceanic plate diverge - Mid Ocean ridges

Seafloor Spreading - plates move apart and create a gap - magma rises upwards through this crust before spilling out as lava - it hardens into basalt rock and forms new ocean floor.

Repeated eruptions make a chain of underwater volcanic mountains along the boundary of the separating plates.

These chains of volcanoes produce landforms known as mid-ocean ridges.

130 mya Seafloor began Sprending

Example- Iceland is a volcanic island and is an example of an island where there is a lot of activity, it is most active country in the world

Growing W→E direction

Continental plates diverge

Rift Valley

-Rift Valleys- are landforms created when a continental plate is pulled apart by convection currents.

- Convection currents stretch he land - it becomes thinner- creates Valley

-Eventually the crust tears apart creating a new divergent boundary.

- Example- East African rift valley

Key Terms

• Divergent

• Convection currents

• Constructive boundaries

• Seafloor spreading

• Mid-ocean ridge

• Rifting

Example questions

-explain how divergent plate boundaries form

-name an example of a divergent boundary and locate it on a map

-explain how seafloor spreading occurs and the impact it has on the landscape

-explain how rift valleys are formed.