This Planet Really Rocks!
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Metamorphic Rocks |
Metamorphic rocks form deep in the earth where high temperature,
Where does the heat come from? The heat comes from magma.
Where does the pressure come from?
Some examples of how metamorphic rocks were changed:
Below is a summary of the major characteristics of metamorphic rocks.
Classified by texture and composition
Rarely has
fossils
May react with acid
May have alternate bands of light and dark minerals
May be composed of only one
mineral, ex. marble & quartzite
May have layers of visible crystals
Usually made of mineral crystals of different sizes
Rarely has pores or openings
May have bent or curved foliation
To learn more about rocks and minerals, click next below:
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Fascinating Facts ||
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The oldest known rock lies in Canada. The Acasta gneiss, a metamorphic
rock, is 3.96 billion years old.
Heat and pressure can change many things. They can even change rocks.
The name for rocks that has been changed is metamorphic (met uh MOR fik)
rocks. Metamorphic comes from Greek words meaning "change" and "form".
great pressure, and chemical reactions cause one type of rock to change
into another type of rock. Metamorphic rocks begin to form at 12-16
kilometers beneath the earth's surface. They begin changing at temperatures of 100 degrees Celsius to 800 degrees Celsius.
If you squeeze and heat a rock for a few million years, it can turn into a new
kind of rock.
The pressure comes from layers of
rock piled on top of layers and layers of rock. The layers on the bottom get squeezed.
The thicker the layers, the more pressure there is.
