Demarcation diagram of rocky coasts in microtidal environments: type A platforms for ρgHl/Sc≥1.3×10−2, type B platforms for 1.7×10−3≤ ρgHl /Sc <1.3×10−2, and plunging cliffs for ρgHl/Sc<1.7×10−3, where Hl is the largest height of waves occurring at a coast, Sc is the compressive strength of rocks forming the coast, ρ is the density of water, and g is the acceleration owing to gravity (Sunamura 1992). Demarcation diagram of rocky coasts in microtidal environments: type A platforms for ρgHl/Sc≥1.3×10−2, type B platforms for 1.7×10−3≤ ρgHl /Sc <1.3×10−2, and plunging cliffs for ρgHl/Sc<1.7×10−3, where Hl is the largest height of waves occurring at a coast, Sc is the compressive strength of rocks forming the coast, ρ is the density of water, and g is the acceleration owing to gravity (Sunamura 1992). Reproduced by permission of John Wiley & Sons. T. Sunamura et al. Geological Society, London, Memoirs 2014;40:203-223 © The Authors 2014