PCC - Mountain Building - Folding and Plateaus Lesson

 

Mountain Building - Folding and Plateaus

Volcanoes are certainly the most dynamic form of mountain-building, but they are by no means the only way that mountains form on the surface of the Earth. The long mountain ranges - the Himalayas, the Andes, the Alps, and the Appalachians - formed by interactions between plate boundaries. These collisions either lifted the mountain ranges up as one plate subducted under the other, or literally folded the rock in the same way that the sheet metal of a fender folds when two cars collide. It can be difficult to imagine the force required to bend solid rock as if it was putty, but it is very easy to find examples of rock that has been folded throughout mountain ranges.

In one of the more complex mountain-building processes, a divergent boundary can result in the formation of a fault-block mountain range. When continental crust is pulled in two opposite directions, multiple fractures (faults) can occur, producing a block in between that sinks down as the two outer sections move apart. This sinking movement may allow an outer section to tilt, with the rising edge of the fault producing a mountain range.

The Sierra Nevada mountain range in California is an example of a fault-block mountain range. This type of mountain range can be distinguished by a very steep slope in one side, with a much more gradual slope on the other side of the range.

Watch the video below to learn more:

Plateaus are large, relatively flat areas that rise above the surrounding land on at least one side.

They can be formed through several different processes, but two of the most common are through uplift caused by magma below the surface or the production of many layers of low viscosity lava, which spread out to cover a large area while building up over repeated eruptions. The Columbia Plateau in the northwestern United States is an example of a volcanic plateau.

 

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