These areas were once wave-cut platforms, but they are now at a higher level than the present sea level. Often, they are old cliff lines with wave-cut notches, caves, arches and stacks behind and above the current beach. The beach was formed when the sea was at that level, but it has since depleted. Raised beaches are common in Scotland, normally at levels of 8m, 15m and 30m (approximate due to differential uplift). On the Isle of Arran near Drumadoon there is a raised beach with many features including King’s Cave. Portland in Dorset is also a raised beach
Coastal Plains/Marine Platform
This is a section of low-lying land adjacent to a coast. Normally, they are separate from the rest of the land due to the presence of nearby landforms. They can form by starting as a continental shelf (flat piece of land below sea level). As sea level falls, land is exposed forming a coastal plain. Alternatively, they form through transportation and deposition of rock, soil and other sediment by river currents into the ocean, forming a build-up. In Western South America, there is a large coastal plain between Andes Mountains and Pacific Ocean.
This is basically just a part of a raised beach, but more specifically, it is the old cliff which has survive destructive processes. They display features like caves, arches and stacks. King’s Cave on the Isle of Arran is found on a relict cliff.
These are similar to raised beaches but take the form of a mudflat instead. The raised stretch follows the regular pattern of a mudflat. It is a sheltered area with pioneer species like halophytes. As sea levels have fallen in the past, the salt marsh grows wider and streams form along it, creating new base levels.