| A | B |
|---|
| rock | a solid material made up of one or more minerals |
| fossil fuels | fuel made from the remains of once-living things |
| conservation | the wise use of natural resources |
| solar energy | energy from the Sun |
| soil | the loose material that covers much of Earth's land surface |
| nonrenewable resource | a resource that cannot be replaced |
| natural resource | any useful material from Earth |
| renewable resource | a resource that can be replaced |
| crust | the thinnest, outermost layer of Earth |
| ore | a rock that can be mined for its minerals |
| contour plowing | the plowing of hilly land in a way that follows the shape of the land |
| terracing | the building of steplike ridges in hilly areas |
| dam building | using boulders, small trees, bushesor boards to stop the formation of gullies |
| strip cropping | the planting of a cover crop between rows of crops |
