Metamorphic Rocks
Metamorphic rocks are the third type we'll look at. They are formed from other rocks that are changed because of heat or pressure.
Formation
Earth movements can cause rocks to be deeply buried or squeezed. As a result, the rocks are heated and put under great pressure. They do not melt, but the minerals they contain are changed chemically, forming metamorphic rocks.
Metamorphic rocks are the third type we'll look at. They are formed from other rocks that are changed because of heat or pressure.
Formation
Earth movements can cause rocks to be deeply buried or squeezed. As a result, the rocks are heated and put under great pressure. They do not melt, but the minerals they contain are changed chemically, forming metamorphic rocks.
What are metamorphic rocks like?
When a metamorphic rock is formed under pressure, its crystals become arranged in layers. Slate, which is formed from shale, is like this. Slate is useful for making roof tiles because its layers can be split into separate flat sheets.
Marble is another example of a metamorphic rock. It is formed from limestone. Metamorphic rocks sometimes contain fossils if they were formed from a sedimentary rock, but the fossils are usually squashed out of shape.
Metamorphic rocks can be formed from any other type of rock - sedimentary or igneous. Remember these two examples of common metamorhpic rocks and where they come from:
Metamorphic Rock examples:
When a metamorphic rock is formed under pressure, its crystals become arranged in layers. Slate, which is formed from shale, is like this. Slate is useful for making roof tiles because its layers can be split into separate flat sheets.
Marble is another example of a metamorphic rock. It is formed from limestone. Metamorphic rocks sometimes contain fossils if they were formed from a sedimentary rock, but the fossils are usually squashed out of shape.
Metamorphic rocks can be formed from any other type of rock - sedimentary or igneous. Remember these two examples of common metamorhpic rocks and where they come from:
- Slate is formed from shale
- Marble is formed from limestone
Metamorphic Rock examples:
The rock cycle
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The rock cycle is a model geologists use to explain the endless cycle of change that rocks undergo. The main idea is that rocks are continually changing from one type to another and back again, as forces inside the earth bring them closer to the surface (where they are weathered, eroded, and compacted) and forces on the earth sink them back down (where they are heated, pressed, and melted). So the elements that make up rocks are never created or destroyed — instead, they are constantly being recycled. The rock cycle helps us to see that the earth is like a giant rock recycling machine!
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