1. Out on a limb! with thanks to Alan Richardson Halesowen College Pete Loader WJEC Update

2. Symmetric Asymmetric What is the Fold Symmetry? Limbs same dip Limbs different dips

3. To quote a well known source: Not a lot of people know that!

4. Symmetrical folds There exists a common misconception that the dips of limbs of a symmetrical fold must have equal dips in opposite directions. This need not be the case, but the lengths of the limbs must be equal. In a symmetric fold the enveloping surface (the surface describing the average dip of a folded bed) is at right angles to the axial surface. RJ Lisle – Geological Structures and Maps WJEC will accept this definition in the new spec. so will indicate the length of the limbs in questions.