In response to compressional stress, geological beds fold in order to minimize dissipation of energy. Given an unconstrained bed, folding does so by correspondingly minimizing bending and thus develops a sinusoidal geometry. In a stratigraphic sequence, beds are geometrically and physically constrained by their neighbours. Similarity must be maintained. To accommodate such constraints while maintaining sinusoidal geometry, less competent layers would need to be subjected to extensive flow. Kinked, yielding and highly localized hinges with straight limbs greatly reduce the geometrical need for deformation. Chevron folds are energetically preferred to conventional sinusoidal folds as they minimize ductile flow to the expense of localized bending.