The Physical Geography of West Africa Directions: Please take out your book and read pages 372-375 and answer the following questions in complete sentences: What is the most important river in West Africa? Why do so many people live along this river? What are the four climate zones in West Africa? What is the Sahel? What is the term to describe why the Sahel is becoming more like the Sahara? Why is this process becoming a serious environmental issue? What are four natural resources found in West Africa? Which is the most valuable?