| A | B |
|---|
| geologists | scientists who study the physical properties of rocks |
| minerals | naturally occuring substances in the earth from which rocks are made |
| color, luster, streak, & hardness | properties of rocks |
| luster | the way light bounces off a mineral |
| streak | color left on a special plate afters mineral is rubbed on it |
| igneous, metamorphic, sedimentary | Rocks are classified into these groups |
| sedimentary rock | rock that is formed in layers |
| igneous rock | formed from hot, molten rock material that has cooled |
| metamorphic rock | rock that has been changed by heat, pressure, or both |
| magma | molten rock that is below the earth's surface |
| large crystals | created when molten rock cools slowly |
| small crystals | created when molten rock cools quickly |
| rock salt, shale, conglomerate, limestone | example of sedimentary rock |
| marble | example of metamorphic rock |
| granite, obsidian, basalt | example of igneous rock |
| limestone | can be changed into marble |
| relative age | describes the age of something compared to another thing |
| rock cycle | never ending process by which rocks are changed from one type into another |
| fossils | provide evidence of plants and animals that lived in the past |
| oldest rocks | found in bottom layers |
| youngest rocks | found in top layers |
| limestone | made of the shells and skeletons of once-living sea animals |
| heat, pressure, weathering, erosion | actions that change rocks |
| gneiss | formed when shale or granite are heated under pressure |
| cleavage | minerals that break along smooth, flat surfaces |
