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