Limestones, such as Portland Stone from the Isle of Portland, are the products of deposition in relatively energy-low environments, such as lagoons. This limestone is composed of microscale ooliths, rounded particles in a finer limestone matrix (micrite). Bedding planes, formed by the different layers of sediment, are present, but they can be relatively inconspicuous compared to the discontinuities produced by changes in the environment within which sediment is deposited, e.g. change from lagoonal to shallow sea.