What is folding?
- Folding is the process whereby two plates collide with each other where some of the layers of rock which make up the crust buckle and form folds.
- Basically two types of fold
- Happens when the layers of rocks buckle upwards to look like an inverted ‘U’
- Happens when layers of rock buckle downwards to look like a “U”
Types of folds
- Symmetrical fold/simple fold
Anticline and Syncline
- A fold where both limbs are equal in steepness because compression from opposite sides is equal.
- Happens when one limb is steeper, because compression is greater from one side than the other.
Overfold / Overturned Fold
- Happens when one fold is pushed over the other limb due to increasing compression
- Both limbs are sloping in the same direction.
- Happens when limbs are nearly parallel to each other.
- Axis is almost horizontal
- Extremely powerful compressional forces which causes recumbent fold to fracture
- Upper part of the recumbent fold thrust forward along the plane of fracture
Different folds Symmetrical fold Asymmetrical fold Overfold Recumbent fold
- How are fold mountains formed?