Describe what happens at a constructive (divergent) plate margin?

A constructive plate margin occurs where two or more plates move apart from each other. Convection currents within the earths mantle force magma upwards towards the Lithosphere, this melts the rock in the upper mantle and forms lava. When this lava makes its way to the surface it solidifies, forming crust which fills the gap between the separating plates. (illustrate with labels) Constructive plate margins within continents form features called rift valleys, such as the East African Rift, between the Nubian and Somali plates, and between oceanic plates form mid-oceanic ridges, such as the mid-atlantic ridge, or volcanic islands, such as Hawaii.