Fold symmetry—a quantitative description

The study of symmetry of a fold has so far been limited to a qualitative distinction between symmetrical or asymmetrical folds. There exists no satisfactory scheme of quantitative definition of the degree of symmetry or asymmetry of a fold. The present paper attempts to address this problem by proposing a classification of folds based on a concept of `degree of asymmetryʹ deduced from Fourier coefficients defining the shape and size of the two limbs of the fold.