| A | B |
|---|
| basin | large, bowl-shaped dip in the land |
| rift valley | narrow valley with steep sides formed millions of years ago by cracks in the earth's crust |
| escarpment | steep cliff at the edge of a plateau |
| savanna | broad grassland containing scattered trees and shrubs |
| sahel | dry, dusty grassland that borders the Sahara |
| plateau | a high, flat landform that rises steeply above the surrounding land |
| tropical rainforest | begins in West Africa and loops south to include all of the Zaire Basin |
| mineral resources | petroleum, oil, gold, copper, silver, uranium, and diamonds |
| cash crop | crop grown to sell |
| drought | lack of rain over time |
| subsistence farming | most of Africa's land is used for this - rasing crops to support your family |
| kinds of cash crops | coffee, tea, and cacao |
| diversifying economy | adding variety to kinds of occupations |
| diversivying economy helps because | countries won't be hurt as much if a cash crop fails or if world prices fall |
| nomads | make their living in the Sahara and move from place to place |
| irrigate | artifically water crops |
| tributaries | small rivers and streams that flow into a larger river |
| Four most important rivers | Nile, Congo, Niger, and Zambezi |
| water resources | not effective for transportation; may be good for hydroelectricity |
| fertile | containing substances plants need in order to grow |
| transportation barrier | physical features that make it difficult to travel |
| silt | tinby bits of rock and dirt that build up on the bottoms of rivers |
| elevation | height of land above sea level |
| plateaus | large raised areas of mostly flat land |
| rift | a deep trench |
| Sahara | largest desert in the world |
