References to bedding surface irregularities in the British Lias limestones as being of secondary origin are reviewed in light of recent studies in South Wales. Protuberances on both top and bottom of some limestone units are the products of loading, vertical stresses created by weight of overburden after burial, and interstratal sliding partly due to local subsidence; some structures are further. distorted by localized, multi-directional, compactional stresses. Four descriptive limestone groups have been identified and post depositional processes contributing to their formation analyzed. Many of the structures described from the Lias of Britain occur in similar Paleozoic sediments of North America, and have yet to be described.