Coastal Environments and Global Change

15 Rock Coasts

Wayne Stephenson

Department of Geography, University of Otago, Dunedin, New Zealand

15.1 Introduction

Rock coasts are the most common coastal type, making up around 80% of the world’s coastline (Emery and Kuhn, 1982), and are found at all latitudes and in all morphogenetic environments (Trenhaile, 1987), including lakes and estuaries. One of the most important management challenges that rock coasts present is that rock coasts are erosional in origin, thus the management of rock coasts may require preservation of erosional processes (and landforms) that are often seen as destructive or are unwanted in other coastal landscapes. This is particularly the case with sea cliffs, where management is commonly applied to stop cliff erosion, resulting in a modification of the cliff form. This can cause erosion of adjacent beaches where the eroding cliff is an important source of sediment for the beach. Such management problems highlight the interconnectedness of rock coasts with other coastal systems and the importance of an integrated approach to rock coast management.

The erosional origin of rock coasts and rock coasts landforms also makes reconstructing the evolutionary history particularly difficult. Understanding how rock coasts have evolved remains unclear, particularly as the influence of changing sea levels over the Quaternary, the role of inheritance (where multiple sea levels have shaped a shoreline), and the relative contributions of a multitude of processes ...