- On Earth's surface, wind and water can break rock into pieces.
- They can also carry rock pieces to another place.
- Usually, the rock pieces, called sediments, drop from the wind or water to make a layer.
- The layer can be buried under other layers of sediments.
- After a long time, the sediments can be cemented together to make sedimentary rock.
- In this way, igneous rock can become sedimentary rock.
- All rock can be heated. But where does the heat come from?
- Inside Earth, there is heat from pressure (push your hands together very hard and feel the heat).
- There is heat from friction (rub your hands together and feel the heat).
- There is also heat from radioactive decay (the process that gives us nuclear power plants that make electricity).
- So, what does the heat do to the rock? It bakes the rock
- Baked rock does not melt, but it does change.
- It forms crystals.
- If it has crystals already, it forms larger crystals.
- Because this rock changes, it is called metamorphic.
- Remember that a caterpillar changes to become a butterfly.
- That change is called metamorphosis.
- Metamorphosis can occur in rock when they are heated to 300 to 700 degrees Celsius