Chapple(1968) gave the concept of finite amplitude, that is the amplitude after which buckling increments are more effectively added and layer shortening is almost non-existent. If a layer with an infinitesimally small amplitude such as a natural or artificial deviation or deflection starts buckling then the finite amplitude is that value of amplitude taken by the fold after which folding or amplification accelerates and thickening of layer or layer parallel strain either stops or rapidly decelerates.