| A | B |
|---|
| Rock cycle | rocks changing from one type to another over time |
| pollution | the adding of harmful materials to soil, air, or water |
| mineral | a solid material found in the ground and made up of elements |
| soil horizons | the soil is divided in to 3 of these |
| sedimentary rock | forms in layers |
| era | a unit of time measured in millions of years |
| ozone | a layer of gas around the Earth |
| alternative energy sources | wind, water, solar energy |
| fossils | the remains of ancient organisms in rock |
| luster | the way a mineral reflects light |
| igneous rock | formed from lava |
| smog | formed from pollution in the air |
| fossil fuels | coal, oil, natural gas |
| coal | anthracite or bituamus |
| aquifer | underwater body of water |
| fossils fuels | used to run machines |
