A coast where layers of different rock run parallel to the coast. The outer hard rock provides a protective barrier to erosion of the softer rocks further in land.
The hard rock (headlands) erodes slower than the softer rock (bays) usually by hydraulic action and the other by abrasion. They are formed only on a discordant coastline and sediment cells are found in between the headlands.
On the area of weakness located on the hard rock, it gets slowly eroded by hydraulic action. After the hard rock has eroded in the middle, the softer rock gets eroded by abrasion at faster and wider rate behind the harder rock. This is only formed on a concordant coastline.
