Click to review the online content. Then answer the question(s) below, using complete sentences. Scroll down to view additional questions. Landforms in Northern Africa

What is an erg, and what challenges do they pose for people?

What is an oasis?

What did scientists believe caused the Rich_at Structure when it was viewed from space by the first astronauts? What do scientist now believe created this landform?

1. crust 1 the metallic layer at the earth's center 2. inner core 3 the firm layer between the crust and the asthenosphere 3. lower mantle 2 the layer surrounding the inner core 4. asthenosphere 4 the semi-solid layer between the top layer and the upper mantle 5. upper mantle 5 the layer between the asthenosphere and lower mantle 6. top layer 6 the earth's outermost layer 7. outer core 7 the hottest part of the mantle