Folded Mountains

The Alps from above

Folded mountains happen when there is a pushing together of part of the earth's crust from the ends, causing it to fold and ripple in the middle. The same phenomenon can be seen if you push the ends of a rug together; it ripples in the center.

The standard explanation is that basically these solid rocks very slowly folded without cracking over long periods of time. However, there seem to be some problems with this explanation, because some of these folds make very sharp hairpin bends without any visible cracking.

This is a problem because, unlike dynamic materials such as glass (which can be bent and folded very slowly in its cold state), most rocks tend to be quite static in nature when cold.

So there are some other explanations that basically state that these rock layers had to be heated to a plastic state prior to folding or been soft sediments that hardened later after the tectonic activity had essentially halted. These explanations also indicate that these mountains may have formed much faster than previously thought.

Some great examples of this mountain type are the Appalachians of North America, the Swiss Alps, the Atlas Mountains of Northern Africa, and the Zagros mountains of Iran. Return to Mountain Formation from Folded Mountains