effectively to introduce each boundary type and relevant discussion, giving the
answer a clear focus that answers the question asked.
Forces clearly identified and explained with relevant examples given.
Where plates separate is referred to as divergent or constructive plate boundaries as new crust is created [2m]. Divergent boundaries can form along oceanic plates, creating mid-ocean ridges and causing seafloor spreading [2m]. An example of this plate boundary is between the North American and Eurasian Plates, which are separating at a rate of 2 cm per year [2m]. As the plates separate, magma rises through the gaps in the crust before cooling to form new basalt rock on the ocean floor [2m]. This rock creates new oceanic crust and gradually widens the Atlantic Ocean. This is called seafloor spreading [2m]. Along the boundary, a chain of underwater volcanoes form the Mid-Atlantic Ridge, which reaches the surface in places, e.g. Iceland [2m]. Iceland formed as layers of newly formed rock piled up before eventually reaching the ocean’s surface to form the island [2m].
Convection currents can also slowly rift continents apart as friction causes the crust to stretch before eventually tearing apart to form a new divergent boundary [2m]. As the crust is stretched, it becomes thinner forming a rift valley, e.g. the East African Rift Valley [2m].
Marking Scheme
Forces identified 2 x 2m Examples given 2 x 2m Best 11 SRPs @ 2m each Total 30/30m
