The relationship of present shore platforms to past sea levels

Extant shore platforms are in process of being graded to LWL, just as the whole terrain is being so graded. Thus platforms occur at all possible heights. Other things being equal, lithology determines height. Ecology is important. On macrotidal stormy coasts (e. g. U. K.) the sea is a dominant factor. In hot humid tropics (e. g. Hawaii) intense weathering is a dominant factor (e. g. water layer weathering). Soft rocks graded to LWL have two profiles of equilibrium: (1) Ramp‐type in non‐soluble rocks. (2) Horizontal‐type in soluble rocks. Platforms exist because the sea is more erosive above LWL than below. Endless variation exists in height of tides and waves, so the sea cannot cut at particular levels. ‘Storm wave’ platforms are hard rocks in exposed sites. They are flat because cut by planar swash (not waves) that returns by channels. Criteria for separating tectonic and eustatic factors are proposed.