Shorelines are isochronous surfaces formed at the interface between land, atmosphere and ocean or lake. They represent morphostratigraphic units that can, in a displaced form, be used to determine mass transfer of water (eustasy) or crust (isostasy), with a resolution determined by the rate of displacement. Because such mass transfers are environmentally controlled, a relationship can exist between specific shoreline types and climatic events. For instance, eustatic raised shorelines are related to interglacial climatic optima, and isostatic marine limits are most commonly related to maximum submergence immediately following glacier wastage. As morphostratigraphic units, displaced shorelines can be related to environmentally sensitive phenomena such as palaeosols or glacial, fluvial, aeolian and periglacial landforms and sediments, so that complex stratigraphic sequences can be constructed, and displaced shorelines can provide a basis for regional correlation. Correlation has been aided by graphical and numerical methods, and shoreline ages can be inferred from stratigraphic position or obtained directly from radiometric dates.