When continents collide (A) or ocean crust subducts (B), rocks are altered by regional metamorphism.
Sometimes rocks are metamorphosed over large areas that are the size of many states or even several countries. This is called regional metamorphism.
How could this happen? What force has the power to change all those rocks? Read the three examples listed below and you will learn what is powerful enough to squish all those rocks until the crystals change.
- Pieces of the Earth's surface layer (called the lithosphere) crash into each other, rocks are squished and changed deep within mountain ranges.
- One piece of the lithosphere is pulled below another and the rocks are altered deep underground by the high pressure and temperature.
- Over time, rock is buried as rocks are deposited above.
What has the power to metamorphose all those rocks? The answer is MOVING ROCKS! Usually regional metamorphism happens as the rocky surface of the Earth moves by plate tectonics!
Last modified June 20, 2003 by Lisa Gardiner.
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