What is a rift valley, and how is it formed?

14. Name three block mountains found in Eastern Africa.

• Ruwenzori Mountains
• Usambara Mountains
• Pare Mountains

15. What is a rift valley, and how is it formed?
A rift valley is a linear depression formed when sections of the Earth's crust pull apart. It is formed by tensional forces that cause the crust to fracture along parallel fault lines. The central block of land between these faults then sinks, creating the valley.

16. Name the major rift valley system found in Eastern Africa.

• The Great Rift Valley

17. Describe the formation of a lava-dammed lake.
A lava-dammed lake forms when a lava flow from a volcanic eruption travels down a valley or river channel and solidifies. This solidified lava acts as a natural dam, blocking the flow of water and causing it to accumulate upstream, thus forming a lake.

18. Give an example of a crater lake in Eastern Africa.

• Lake Chala