| A | B |
|---|
| physical weathering | the breaking of rocks into smaller pieces |
| chemical weathering | a process that changes the minerals in rocks |
| oxide | a material formed when oxygen joins chemically with a mineral |
| erosion | moving of weathered rock and soil |
| runoff | water that drains off land |
| sediment | soil, sand, and rocks carried by wind and water |
| deposition | the dropping of sediments moved by erosion |
| glacier | a large, slow-moving mass of ice |
| ice age | a period of thousands of years when snow and ice cover much of the earth |
| rock cycle | the ways that rocks change from one form to another |
| igneous rock | rock formed from cooled magma |
| crystal | a substance made up of atoms arranged in a repeating pattern. All the crystals of a mineral have the same basic shape, but can be different in size. |
| sedimentary rock | rock that forms from cemented or pressed sediments |
| metamorphic rock | rock formed when heat and pressure change the minerals in igneous or sedimentary rocks |
| petrify | to replace molecules in dead organisms with minerals |
| mold | a hollow left in sediment after an organism dissolves |
| imprint | a footprint or other track of an organism that has been preserved in rock |
| cast | a fossil formed by sediments filling a mold |
