Constructive And Conservative Boundary Landforms

Question 1

East African Rift Valley

Answer 1

Formed as the African plate splits in two, the Great East African rift valley contains Lake Victoria and Mount Kilimanjaro.
Constructive feature

Question 2

East African Rift Valley formation

Answer 2

1. Elevated heat flow from the mantle caused a pair of thermal ‘bulges’ in central Kenya and the Afar region in Ethiopia.
2. As the bulges formed they stretched and fractured the crust into a series of faults
3. Convectional currents in the asthenosphere cause the extension of the crust. As the crust extends grabens (down dropped blocks) and horsts (up thrown blocks) are formed
4. As the rift continues to extend parts of the crust become thin enough for oceanic type basalts to be erupted, signalling the formation of new oceanic crust
5. Eventually the African plate will split in two, forming the Nubian plate and the Somalian plate.

Question 3

Volcanic activity in East African rift

Answer 3

. The area associated with volcanic activity has much thinner crust, suggesting that tension in the lithosphere is causing the plate to thin as it starts to split
. The line of the African rift is thought to be where a new plate boundary is emerging. This would begin the formation of a new ocean.
. Volcanic activity in the area of thinner crust has resulted in rising magma escaping forming Kilimanjaro (5,891m asl)

Question 4

Constructive boundaries

Answer 4

. Warping of crust upwards takes place as magma rises as plates are driven apart by convection currents in the mantle
. Heat cracks the crust and weakens it causing thermal bulges
. Bulges stretched and cracked the crust
. Io occurs

Question 5

Conservative boundaries

Answer 5

. Unknown meaning they are dangerous - can cause very powerful earthquakes